Rozprawy doktorskie na temat „Nutrient removal”

High concentrations of dissolved nutrients in stormwater have been identified as contributing to eutrophication of receiving waterways near urban areas. To reduce dissolved nutrient concentrations in stormwater a range of devices such as wetlands and bioretention systems are used. Bioretention systems are increasingly employed for their supposedly high nutrient removal capacity, however very little is known about their treatment efficiency or the chemical and biological mechanisms controlling their function. This research aimed firstly to test and compare the efficiency of different bioretention system designs for the removal of dissolved nutrients from stormwater, and secondly to investigate the chemical and biological mechanisms responsible for the nutrient removal (sorption, microbial uptake, and plant uptake). Bioretention mesocosms were built in plastic containers (1 m x 0.5 m x 0.5 m). Three different media treatments were built, representing those most commonly used: gravel, fine sand and loamy-sand. To assess the nutrient removal capacity of plants, vegetated and unvegetated examples of each media type were made. The mesocosms were regularly irrigated with tap water for six months, and then regularly irrigated with synthetic stormwater for a further six months to ensure that the treatment performance assessed would represent fully established systems. The synthetic stormwater solution was based on field measurements of stormwater, and was made using a combination of inorganic chemicals and organic fertilisers. By incorporating organic carbon and major cations (Ca, Mg, Na, K), the measured treatment performance of the biofilters would be more realistic than previous studies that did not corporate these compounds. Some mesocosms were watered only with tap water so that the effect of frequent fertilisation (enrichment) could be compared. It was expected that vegetated media would enhance nutrient removal directly through plant uptake, and indirectly by stimulating microbial productivity and microbial uptake in the rhizosphere. Nutrient removal was evaluated by comparing the influent to the effluent. Detention times of 24 and 72 hours were compared to test if longer contact periods resulted in greater nutrient removal. The mesocosms were also flushed with tap water (no nutrients) to determine the proportion of entrained nutrients that might subsequently leach from the media. Vegetated bioretention mesocosms were much more efficient than unvegetated systems at removing total nitrogen (63 – 77 % removal compared to -12 – 25 %) and total phosphorus (85 – 94 % removal compared to 31 – 90 %). The vegetation effect did not improve dissolved organic carbon removal but there was a difference between soil types, with smaller particle size media removing more organic carbon. Enriched mesocosms removed similar quantities of nutrients to non-enriched mesocosms. Extending the detention time from 24 hours to 72 hours slightly increased the removal of total nitrogen from the vegetated mesocosms, but reduced total nitrogen removal from unvegetated mesocosms. When flushed with tap water, inorganic and organic forms of nitrogen and phosphorus leached from the unvegetated mesocosms, but were mostly retained within the vegetated mesocosms...
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Engineering
Science, Environment, Engineering and Technology
Full Text

Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. At the beginning of this study, granular sidestream deammonification was becoming well-established in Europe, but there was virtually no experience with startup or operation of these processes in North America. The experience gained from optimization of the sidestream deammonification moving bed biofilm reactor (MBBR) in this study, including the novel pH-based aeration control strategy, has influenced the startup procedure and operation of subsequent full-scale installations in the United States and around the world. Long startup time remains a barrier to the implementation of sidestream deammonification processes, but this study was the first to show the benefits of utilizing media with an existing nitrifying biofilm to speed up anammox bacteria colonization. Utilizing media with an established biofilm from a mature integrated fixed film activated sludge (IFAS) process resulted in at least five times greater anammox activity rates in one month than virgin media without a preliminary biofilm. This concept has not been testing yet in a full-scale startup, but has the potential to drastically reduce startup time. False dissolved oxygen readings were observed in batch scale denitrification tests, and it was determined that nitric oxide was interfering with optical DO sensors, a problem of which the sensor manufacturers were not aware. This led to at least one sensor manufacturer reevaluating their sensor design and several laboratories and full-scale process installations were able to understand their observed false DO readings. There is an industry-wide trend to utilize influent carbon more efficiently and realize the benefits of mainstream shortcut nitrogen removal. The A/B pilot at the HRSD Chesapeake Elizabeth Treatment provides a unique chance to study these strategies in a continuous flow system with real wastewater. For the first time, it was demonstrated that the presence of influent particulate COD can lead to higher competition for nitrite by heterotrophic denitrifying bacteria, resulting in nitrite oxidizing bacteria (NOB) out-selection. TIN removal was affected by both the type and amount of influent COD, with particulate COD (pCOD) having a stronger influence than soluble COD (sCOD). Based on these findings, an innovative approach to achieving energy efficient biological nitrogen removal was suggested, in which influent carbon fractions are tailored to control specific ammonia and nitrite oxidation rates and thereby achieve energy efficiency in the nitrogen removal goals downstream. Intermittent and continuous aeration strategies were explored for more conventional BNR processes. The effect of influent carbon fractionation on TIN removal was again considered, this time in the context of simultaneous nitrification/denitrification during continuous aeration. It was concluded that intermittent aeration was able to achieve equal or higher TIN removal than continuous aeration at shorter SRTs, whether or not the goal is nitrite shunt. It is sometimes assumed that converting to continuous aeration ammonia-based aeration control (ABAC) or ammonia vs. NOx (AvN) control will result in an additional nitrogen removal simply by reducing the DO setpoint resulting in simultaneous nitrification/denitrification (SND). This work demonstrated that lower DO did not always improve TIN removal and most importantly that aeration control alone cannot guarantee SND. It was concluded that although lower DO is necessary to achieve SND, there also needs to be sufficient carbon available for denitrification. While the implementation of full-scale sidestream anammox happened rather quickly, the implementation of anammox in the mainstream has not followed, without any known full-scale implementations. This is almost certainly because maintaining reliable mainstream NOB out-selection seems to be an insurmountable obstacle to full-scale implementation. Partial denitrification/anammox was proven to be easier to maintain than partial nitritation/anammox and still provides significant aeration and carbon savings compared to traditional nitrification/denitrification. There is a long-standing interest in combining shortcut nitrogen removal with biological phosphorus removal, without much success. In this study, biological phosphorus removal was achieved in an A/B process with A-stage WAS fermentation and shortcut nitrogen removal in B-stage via partial denitrification.
Doctor of Philosophy
When the activated sludge process was first implemented at the beginning of the 20th century, the goal was mainly oxygen demand reduction. In the past few decades, treatment goals have expanded to include nutrient (nitrogen and phosphorus) removal, in response to regulations protecting receiving bodies of water. The only practical way to remove nitrogen in municipal wastewater is via biological treatment, utilizing bacteria, and sometimes archaea, to convert the influent ammonium to dinitrogen gas. Orthophosphate on the other hand can either be removed via chemical precipitation using metal salts or by conversion to and storage of polyphosphate by polyphosphate accumulating organisms (PAO) and then removed in the waste sludge. Nitrification/denitrification and chemical phosphorus removal are well-established practices but utilize more resources than processes without nutrient removal in the form of chemical addition (alkalinity for nitrification, external carbon for denitrification, and metal salts for chemical phosphorus removal), increased reactor volume, and increased aeration energy. Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. Partial nitritation/anammox is a relatively new technology that has been implemented in many full-scale sidestream processes with high ammonia concentrations, but that has proven difficult in more dilute mainstream conditions due to the difficulty in suppressing nitrite oxidizing bacteria (NOB). Even more challenging is integrating biological phosphorus removal with shortcut nitrogen removal, because biological phosphorus removal requires the readily biodegradable carbon that is diverted. Partial denitrification/anammox provides a viable alternation to partial nitritation/anammox, which may be better suited for integration with biological phosphorus removal.

Although, microalgal wastewater treatment systems represent an efficient and economical alternative to conventional processes, the use of marine microalgae to remove nutrients from wastewaters has not been extensively researched and few studies have been made in temperate and high latitude areas, where climate may limit treatment. In this study, 102 marine microalgal species, including 66 local endemic isolates from St Andrews Bay, Fife, Scotland, were screened under batch and continuous culture. Species were selected for their ability to remove high concentrations of ammonium and ortho-phosphate from primary treated sewage (diluted 1:1 with sterile seawater) while remaining dominant in culture. Abiotic removal of ammonium and ortho-phosphate at high pH was found to be low from saline media, indicating that much of the nutrient removal from the seawater:wastewater mixture was by algal uptake. Many of the best-treating species grew over a wide range of temperature (10-25 °C), and their growth was not inhibited by the low salinity of the 1:1 diluted wastewater. Seven best-treating species continuously removed >80 % ammonium and >70% ortho-phosphate when cultured in 20 litre mini-ponds (modelled on high-rate ponds) under ambient summer conditions over two weeks. These were all endemic isolates including six bacillariophyceaen isolates (of which three were strains of Phaeodactylum tricornutum), and a species of the cyanophyceaen Oscillatoria. Two isolates (Oscillatoria and an unidentified bacillariophyceaen SA91B33) with adherent properties, continuously removed 100 % of both ammonium and ortho-phosphate when tested in a corrugated raceway designed to provide a large surface area for attachment. Preliminary experiments further showed the best-treating species to be capable of removing nutrients from eel aquaculture effluent. The abilities of marine microalgal species to remove high concentrations of nutrients, remain in unialgal culture and grow over a range of environmental conditions are indicative of their potential for use in wastewater treatment systems in temperate areas.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 45-46).
Floating Treatment Islands (FTIs) have been studied as a method to mitigate the risks associated with high nutrient levels in contaminated water. The goal of this project was to compare fractional treatment rates by a series of FTIs located at the edge of a channel, allowing the center channel to remain clear. Experiments were performed using a scaled-down model floating treatment island (FTI) with a 19 x 24.5 cm x 10 cm root zone modeled using 3.6 mm diameter dowel rods (n = 75/135 cm 2, low flow blockage) attached to the inside wall of a 1.2 m wide x 16 m long flume. Three cases were considered, with four FTIs spaced at various distances based on the length scale L of the FTI: the closest spacing had each FTI located 2L downstream of the last, the mid-range spacing were placed 4L apart, and the farthest spacing had each FTI 8L past the last. Based on the cross-sectionally averaged flow rates measured at the leading and trailing edges of the root zone, treatment rates within the root zone were estimated using a first-order kinetic model, and an iterative method was used to solve for the fractional treatment by the series of FTIs. This paper explores the effects of various parameters on treatment, including flow rates and velocity recovery, biological uptake rate, and island size. Finally, the researcher evaluated which setup provided the most treatment for a given number of treatment islands. It was found that the 8L spacing provided the best treatment, significantly more than the 4L or 2L spacing for k < 10 day⁻¹ according to the results of a two-sample t-test. For a set of 8L spaced FTIs with an uptake rate of 1 day⁻¹ with a cross-sectional coverage of 13.6%, it would be possible to reduce the upstream nutrient concentration by 25% over a channel length of roughly 3.5 km, 50% over a channel length of 10 km, and 90% over a channel length of approximately 32 km. These treatment rates could have the potential to mitigate the risk of eutrophication in sufficiently long channels.
by Kali M. Rosendo.
M. Eng.

Pharmaceuticals that are intended for human use are frequently detected in the aquatic environment. This is predominantly from the excretion of pharmaceuticals by patients, in their urine and faeces, which subsequently enter sewage treatment plants. Sewage treatment provides a final opportunity for pharmaceutical removal, prior to discharge into the environment, however, removal is often incomplete. Once in the environment, pharmaceuticals have the potential to cause effects on aquatic organisms. Sewage treatment plants, that are designed to meet statutory discharge consents for nutrients, are increasing in number. These plants, capable of biological nutrient removal, are understudied for the removal efficiencies of pharmaceuticals. This thesis presents research findings on the behaviour, fate and removal of selected pharmaceuticals in a bespoke laboratory rig, and in operational biological nutrient removal sewage treatment plants. Pharmaceuticals possessing a broad range of physical and chemical properties were selected for this research, they included: salicylic acid, caffeine, propranolol, diclofenac and carbamazepine. Sensitive chromatographic methods were developed to quantify the analytes in a laboratory sequencing batch reactor rig and in operational plants. Radiolabelled 14C isotopes of salicylic acid, caffeine, propranolol and diclofenac were dosed into the laboratory rig. The compounds exhibited different behaviours during a simulated sewage treatment process. Salicylic acid and caffeine produced the highest amount of biodegradation, with 25.2% and 14.5% of the radiolabel mineralised to 14CO2 in the rig. However, parent degradation is likely to have been higher, since neither compound could be detected in the effluent by specific chemical analysis. These findings were replicated in the operational sewage treatment plants, with > 97% removal of both pharmaceuticals, in all three plants investigated. Propranolol and diclofenac were less affected by biodegradation processes, and produced 3.7% and 0.2% mineralisation, respectively, in the laboratory rig. Furthermore, 33.8% of the radioactivity associated to 14C propranolol was detected in the rig solids. These compounds showed insignificant removal from two operational plants; 6.8% and 20.9% (propranolol) and -0.9% and -39.4% (diclofenac). Monitoring of operational plants showed that concentrations of propranolol were highest in the activated sludge tanks at all three sites. This supports the findings from the rig, that propranolol interacts with the sludge, which might be more significant in plants with lower sludge wastage rates, such as sequencing batch reactors. This could have implications for the terrestrial environment, and therefore, terrestrial risk assessments should be refined accordingly. Monitoring of the operational sewage treatment plants highlighted the widespread presence, and recalcitrant behaviour, of carbamazepine during biological sewage treatment. Future work should focus on investigating the mechanisms of removal, of this pharmaceutical in the laboratory sequencing batch reactor. This work highlighted the problems biological systems face in effectively removing recalcitrant pharmaceuticals. Advanced wastewater treatment should be considered, if complete removal is desired.

High nitrogen and phosphorus content in storm water runoff has affected groundwater, springs and surface water by impacting ecosystem integrity and human health. Nitrate may be toxic and can cause human health problem such as methemoglobinemia, liver damage and even cancers. Phosphorus may trigger the eutrophication issues in fresh water bodies, which could result in toxic algae and eventually endanger the source of drinking waters. Sorption media with mixes of some recycled materials, such as sawdust and tire crumb, combined with sand/silt and limestone, becomes appealing for nutrient removal in environmental management. This paper presented is a specific type of functionalized filtration media, Langmuir and Freundlich isotherms with reaction kinetics for nutrient removal using a suite of batch tests represented. Pollutants of concern include ammonia, nitrite, nitrate, orthophosphate and total dissolved phosphorus. Application potential in storm water management facilities, such as dry ponds, is emphasized in terms of life expectancy and reaction kinetics. As compared to the natural soil that is selected as the control case in the column test, our green sorption media mixture is proved relatively effective in terms of removing most of the target pollutants under various influent waste loads.
M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engr MSEnvE

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.
Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Environmental Sciences and Engineering." Discipline: Environmental Sciences and Engineering; Department/School: Public Health.

Phosphorus contamination of surface waters is a primary water quality concern in the agricultural watershed of Pike River in southern Québec. Surface waters from Walbridge creek, a tributary of the Pike River, were diverted into a small constructed wetland consisting of three basins laid out in series to evaluate nutrient (nitrogen and phosphorus) retention within the system. Hydraulic and nutrient loading rates to the constructed wetland were highly variable in time, with peak rates of loading occurring during runoff events in the watershed, with a mean hydraulic loading rate of 25 cm/day. The wetland retained 8.47 kg total phosphorus, which corresponded to 44 % of total phosphorus inputs (19.3 kg) and it also retained 132.5 kg nitrates, which represented 13 % of nitrate inputs (995 kg) to the wetland, over 4 years (2003-06) of seasonal (May-Nov) operation. Annual mean nutrient retention rates (1.7 g total P m-2 year-1 and 27.3 g NO3- m-2 year-1) were within the range of values reported in the literature for constructed wetlands treating agricultural runoff. This study therefore provided additional evidence supporting the use of small constructed wetlands as nutrient traps in agricultural watersheds in a moderate Canadian climate. A first generation wetland model was also developed using MATLABTM programming language to simulate phosphorus cycling in the wetland. The model was evaluated as a prediction tool of effluent particulate phosphorus and ortho-phosphate concentrations. Much more work needs to be done to improve the accuracy of the model simulations.
Sur le plan de la qualité de l'eau, la première source de préoccupation dans le bassin agricole de la rivière aux Brochets concerne les teneurs élevées en phosphore. Une partie des eaux du ruisseau Walbridge, un tributaire de la rivière aux Brochets, a été détourné vers un marais filtrant aménagé en dérivation du ruisseau. Le marais est composé de trois bassins en série et la rétention des éléments nutritifs (azote et phosphore) été évaluée dans ce système. Les apports hydrauliques et nutritifs ont été mesurés de façon continue durant la période de croissance végétale (Mai-Nov) de 4 années (2003-06). En moyenne, l'apport hydraulique au marais filtrant était de 25 cm/jour. La rétention de phosphore total (8.47 kg) dans le système représentait 44% des apports en phosphore total (19.3 kg), tandis que la rétention de nitrates (132.5 kg) représentait 13 % des apports en nitrates (995 kg). Les taux de rétention moyens exprimés par unité de surface du système (1.7 g phosphore total m-2 année-1 et 27.4 g NO3- m-2 année-1) se comparent aux valeurs de la littérature. Cette étude apporte des données additionnelles pour faire la preuve que les marais filtrants en climat tempéré canadien ont la capacité d'assainir les cours d'eau en milieu agricole. Un modèle a aussi été développé, à l'aide du langage de programmation MATLABTM, pour simuler le cycle du phosphore dans le marais. Il reste encore beaucoup de travail à faire pour améliorer les prédictions du modèle.

A study was conducted to assess the efficiency of a constructed wetland for sediment and nutrient removal from a riverine source containing non-point source pollution (NPS) in a Nordic climate. The constructed wetland, built near the town of Mystic, Southern Quebec, consists of a sedimentation basin, a sinuous subsurface horizontal flow section and an open water body or pond that continuously receives up to 5% of Walbridge Creek. Flow into and through the system is controlled by gravity. There is a gate on the intake structure, which allows inflow into the wetland to be adjusted, along with three composite weirs; located at the outlet of each section of the wetland. Water samples were analyzed for orthophosphates (PO4), dissolved phosphorus (DP), total phosphorus (TP), ammonium (NH4+) and nitrates (NO3-) The study occurred from May to December 2003 and from May to December 2004. In 2003, there was a 33.6% reduction in TP load from intake to outlet with a retention rate of 2.23 g m-2 year-1. The greatest reduction in TP load during 2003 took place during the summer months (32.2%). In 2004, there was a further reduction of 42.8% in TP load from intake to outlet with a retention rate of 1.56 g m-2 year-1 compared to 2003. The largest reduction in TP load during the operational year of 2004 took place during the summer months (43.7%). Within the wetland, both the submerged flow section and open water basin showed similar and significant reductions of TP load in 2003 and 2004 annually and seasonally. Both annually and seasonally in 2003, NO3- showed no significant decrease in load from intake to outlet or within portions of the wetland. In 2004, there was a 22% annual load reduction from intake to outlet with a retention rate of 43.9 g m-2 year-1. The largest reduction in NO3- load during 2004 took place during the summer months (25.6%). Within the wetland, the submerged flow section showed the greatest reduction in NO3- concentrations annually and during the summer months of 2004. These results confirm the range of treatment efficiencies that can be achieved using a constructed wetland for NPS pollution in a Nordic climate.

Includes bibliography.
In conventional nitrification-denitrification biological excess phosphorous removal (NDBEPR) activated sludge systems, such as the UCT system for example, both nitrification and phosphorous uptake (P uptake) occur simultaneously in the, usually large, aerobic reactor. In the UCT system the nitrate load to the anoxic reactor is limited by the a-recycle (i.e. system constraint recycle from the aerobic to the anoxic reactor) and the internal aerobic nitrification performance. The latter process, is mediated by the nitrifiers having a slow growth rate of 0.45/d, governs the sludge age of the biological nutrient removal activated sludge (BNRAS) system and thus results in long (20 - 25 day) sludge ages and large aerobic mass fraction requirements to nitrify completely. However, if stable nitrification could be achieved outside the BNRAS external nitrification (EN) system then nitrification and the suspended solids sludge age become uncoupled allowing greater flexibility into the BNRAS system.

Summary in English.
Bibliography: leaves 5.1-5.7.
Biological nutrient removal activated sludge (BNRAS) systems have become the preferred treatment system for advanced municipal wastewater treatment in South Africa. They have proven to be cost-effective systems that produce effluents of excellent quality that can be re-introduced to the receiving water bodies without a significant negative impact on the scarce surface water of South Africa. The widespread implementation of the BNRAS system has drawn attention to some of the weaknesses of the system, predominantly (i) the long sludge ages and resulting large biological reactor volumes required for nitrification, (ii) filamentous organism bulking of the sludge that develops in the system, (iii) treatment of the P rich waste sludge from the system and (iv) containment of the large mass of P in the sludge during a failure of the aeration in the system. In order to overcome the first two weaknesses of the system, it is proposed to separate the process of nitrification from the BNRAS mixed liquor and achieve nitrification externally to the BNRAS system.

L'utilisation des microalgues dans le traitement des eaux usées est de plus en plus étudiée pour intégrer/remplacer les systèmes de traitement actuels permettant d'éliminer les nutriments et autres polluants. Cependant, l’utilisation des microalgues dans le traitement des eaux usées en est principalement au stade de la recherche, par exemple faible élimination des nutriments et croissance de la biomasse des microalgues. Le but de cette thèse était de permettre une élimination efficace des éléments nutritifs et de la matière organique des eaux usées par les microalgues tout en favorisant la production de biomasse de microalgues. C. vulgaris et S. acuminatus ont été cultivés dans des photobioréacteurs discontinus avec des digestats issus de la digestion anaérobie (AD) de boues biologiques de boue de vidange provenant d’une station d’épuration municipale (ADMW) et d’une usine de traitement des eaux usées d’une usine de pâtes et papiers (ADPP). Les rendements d’élimination de l’ammonium étaient supérieurs à 97% lorsque les deux microalgues étaient cultivées séparément dans de l’ADPP. Toutefois, 24 et 44% de l’ammonium ont été retirés de l’ADMW par C. vulgaris et S. acuminatus, respectivement. Les deux microalgues ont efficacement éliminé le phosphate (> 96%), tandis que la couleur (74–80%) et la DCO soluble (27–39%) ont été partiellement éliminées de ADMW et d'ADPP. La plus forte concentration de biomasse de S. acuminatus (7,8 à 10,8 g L-1 VSS) dans l'ADPP figure parmi les rendements les plus élevés signalés pour les microalgues dans les eaux usées réelles. Des rendements de biomasse supérieurs de S. acuminatus ont été obtenus dans de l'ADPP thermophile (10,2 ± 2,2 et 10,8 ± 1,2 g L-1) par rapport à de l'ADPP mésophile prétraité (7,8 ± 0,3 g L-1). En outre, les concentrations les plus élevées en biomasse et en méthane de microalgues ont été obtenues dans le même système intégré de culture de AD et de microalgues. Les concentrations de fer (0,1, 1,0 et 1,9 mg L-1) et de sulfure de soufre (3,7, 20 et 35,8 mg L-1) affectaient davantage l'efficacité de l'élimination de l'azote et la concentration de la biomasse de microalgues davantage dans les ammonium probablement dû à différents mécanismes d'assimilation de microalgues. Dans cette étude, le milieu contenant du nitrate comme source d'azote avec 1,0 mg de L-1 de fer et 35,8 mg de L-1 de sulfate et de soufre a permis d'obtenir la plus forte concentration de biomasse de microalgues. L'effet de la concentration en fer sur l'efficacité d'élimination des nitrates et la croissance des microalgues était plus significatif que la concentration en sulfate, alors que l'effet d'interaction entre le sulfate et le fer n'était pas observé. L'efficacité moyenne d'élimination de l'ammonium (14 à 30%) et la concentration en biomasse de microalgues (0,55 à 1,17 g de POC L-1) dans un photobioréacteur à membrane à flux continu ont été améliorées par addition de zéolite (0,5 g L-1). La zéolite fournissait probablement un habitat pour la croissance attachée de microalgues et une grande disponibilité d'ammonium pour la croissance à la surface de la zéolite en raison de l'adsorption d'ammonium par la zéolite. Une augmentation supplémentaire de la concentration en zéolite (de 0,5 à 1 et 5 g L-1) n’a pas amélioré l’efficacité de l’élimination de l’ammonium ni la concentration de la biomasse, probablement en raison de la turbidité accrue de la solution provoquée par la fragmentation de la zéolite ajoutée en particules plus fines, ce qui a réduit la disponibilité de lumière. Ces travaux ont montré la possibilité d'utiliser des microalgues dans le traitement des eaux usées pour éliminer efficacement les nutriments et les matières organiques, tout en favorisant la croissance des microalgues. La sélection d'espèces de microalgues adaptées aux eaux usées spécifiques pour éliminer les nutriments et les matières organiques est essentielle pour promouvoir les applications de traitement des eaux usées à base d'algues
Use of microalgae in wastewater treatment has been increasingly studied to integrate with or replace the present treatment systems for removal of nutrients and other pollu-tants. The potential advantages of this integration (wastewater treatment and microalgal cultivation) could be simultaneous recovery of nitrogen and phosphorus and the use of produced microalgal biomass as feedstock for e.g. biofuel, fertilizer and/or energy. However, the use of microalgae in wastewater treatment is mainly in research stage due to e.g. low nutrient removal and microalgal biomass growth. The aim of this thesis was to enable efficient nutrient and organic matter removal from wastewaters by mi-croalgae while promoting microalgal biomass production. Chlorella vulgaris and Scenedesmus acuminatus were successfully grown in batch photobioreactors with liquid digestates from anaerobic digestion (AD) of biosludge from a municipal wastewater treatment plant (ADMW) and a pulp and paper mill wastewater treatment plant (ADPP). The final ammonium removal efficiencies were above 97% when cultivating both microalgae separately in ADPP, however, only 24% and 44% of ammonium were removed from ADMW by C. vulgaris and S. acuminatus, respectively. Both microalgae efficiently removed phosphate (>96%), while color (74–80%) and sol-uble COD (27–39%) were partially removed from ADMW and ADPP. The obtained highest S. acuminatus biomass concentration (7.8–10.8 g L-1 VSS) in ADPP is among the highest yields reported for microalgae in real wastewaters. Higher S. acuminatus biomass yields were obtained in thermophilic ADPP (without and with pretreatment prior to AD: 10.2±2.2 and 10.8±1.2 g L-1, respectively) than in pretreated mesophilic ADPP (7.8±0.3 g L-1). In addition, the highest microalgal biomass concentration and methane yields were obtained in the same integrated AD and microalgal culti-vation system (thermophilic AD with pretreatment).The iron (0.1, 1.0, and 1.9 mg L-1) and sulfate-sulfur (3.7, 20, and 35.8 mg L-1) concen-trations were found to affect nitrogen removal efficiency and microalgal biomass con-centration more in the media with nitrate than with ammonium, probably due to different microalgal assimilation mechanisms for nitrate and ammonium. In this study, synthetic medium with nitrate as nitrogen source with 1.0 mg L-1 iron and 35.8 mg L-1 sulfate-sulfur enabled the highest microalgal biomass concentration. The effect of iron concentration on nitrate removal efficiency and microalgal growth was more significant than that of sulfate concentration, while the interaction effect between sulfate and iron was not observed. The average ammonium removal efficiency (14 to 30%) and microalgal biomass con-centration (0.55 to 1.17 g particulate organic carbon per L) in continuous-flow mem-brane photobioreactor were promoted by adding a low concentration of zeolite (0.5 g L-1). The zeolite likely provided a habitat for attached growth of microalgae and high availability of ammonium for growth on the surface of the zeolite due to ammonium adsorption to zeolite. Further increase in zeolite concentration (from 0.5 to 1 and 5 g L-1) did not improve ammonium removal efficiency or biomass concentration. This was likely due to the increased solution turbidity caused by breaking apart of added zeolite particles into finer particles, which reduced light availability.In summary, this work showed the possibility of utilizing microalgae in wastewater treatment to efficiently remove nutrients and organic matter, and simultaneously pro-mote microalgal growth. Selecting suitable microalgal species for the specific wastewater to remove nutrients and organic matter is essential to promote algae-based wastewater treatment applications

In north central Texas, USA, free-water surface wetlands have been constructed to treat pre-treated wastewater effluent from the Trinity River. Water quality and vegetation data from the first two years of operation (June 2003 to May 2005) were used to determine cell-to-cell and system-wide removal efficiency of total suspended solids (TSS), total phosphorus (TP) and total nitrogen (TN). The wetland system consisted of one non-vegetated sedimentation basin and a series of four connected, vegetated wetland cells. Temporal analyses displayed varying monthly, seasonal and yearly trends of the wetlands’ concentration of the three parameters. Spatial analysis results confirmed that TSS, TP and TN concentrations were greater at the beginning of the system as compared to the end of the wetland system. Percent reduction analyses showed that the second wetland cell (WC2) was the most efficient in TSS, TP and TN removal, while the last wetland cell (WC4) had the lowest reduction of the three parameters. TSS removal was significant (α = 0.05) moving consecutively among the sites in the wetland system, with exception to the last wetland cell. TP removal was only significant (α = 0.05) moving from the third wetland cell (WC3) to WC4, while TN removal was significant (α = 0.05) moving from the sedimentation basin to the first wetland cell (WC1) and then again moving from WC3 to WC4. Overall removal efficiency of the wetland system (from the Trinity River to WC4) was quite high, with reductions over 97% for TSS, 47% for TP and 67% for TN. N:P ratios decreased moving consecutively throughout the field-scale wetlands. Vegetation analyses found WCs 1 and 3 to contain the greatest vegetation species richness, while WC2 had the lowest richness. The vegetative composition of the four cells was mostly the same. A comparison was conducted between the nutrient reduction efficiency and vegetation data of this wetland system with data from a pilotscale wetland system that was operated from 1992 to 2000. The findings of this study suggest that during the first two years of operation, the wetland system’s performance is comparable to the pilot-scale wetlands which were operated for eight years.

The objective of this dissertation was to provide a controlled comparison of identical continuous flow BNR processes both with and without prefermentation in order to provide a stronger, more quantitative, technical basis for design engineers to evaluate the potential benefits of prefermentation to EBPR in treating domestic wastewater. In addition, the even less understood effect of prefermentation on denitrification kinetics and anoxic phosphorus (P) uptake was studied and quantified. Other aspects of BNR performance, which might change due to use of prefermentation, will also be addressed, including anaerobic stabilization. Potential benefits to BNR processes derived from prefermentation are compared and contrasted with the more well-known benefits of primary clarification. Finally, some biokinetic parameters necessary to successfully model both the activated sludge systems and the prefermenter were determined and compared for the prefermented versus the non-prefermented system. Important findings developed during the course of this dissertation regarding the impact of prefermentation upon the performance of activated sludge treatment systems are summarized below: • For a septic COD-limited (TCOD:TP < 40:1) wastewater, prefermentation was found to enhance EPBR by 27.7% at a statistical significance level of alpha=0.05 (95% confidence level). • For septic P-limited (TCOD:TP > 40:1) wastewaters, prefermentation was not found to improve EBPR at a statistical significance level of alpha=0.05 (95% confidence level). • The increased anaerobic P release and aerobic P uptakes due to prefermentation correlated with greater PHA formation and glycogen consumption during anaerobiosis of prefermented influent. • Improvements in biological P removal of septic, non-P limited wastewater occurred even when all additional VFA production exceeded VFA requirements using typical design criteria (e.g. 6 g VFA per 1 g P removal). • Prefermentation increased RBCOD content by an average of 28.8% and VFA content by an average of 18.8%, even for a septic domestic wastewater. • Prefermentation increased specific anoxic denitrification rates for both COD-limited (14.6%) and P-limited (5.4%) influent wastewaters. This increase was statistically significant at alpha=0.05 for COD-limited wastewater, but not for P-limited wastewater.
Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering

As one of the largest and most productive estuaries in the United States, the Chesapeake Bay is a great economic, ecological, and cultural asset to the Mid-Atlantic region. Excess nitrogen and phosphorus discharge, however, has contributed to reduced levels of dissolved oxygen in various locations throughout the Bay. In 2010, the EPA developed a Total Maximum Daily Load (TMDL) for the entire watershed that established nutrient reduction targets to achieve Bay water quality objectives. The TMDL required states in the Chesapeake Bay watershed to create implementation plans to meet nutrient reductions. Maryland and Virginia specifically established stringent point source regulatory policies designed to meet point source reduction targets. Point source control programs created financial incentives for reducing nutrient discharge beyond regulatory requirements. This thesis will examine the extent to which Maryland and Virginia wastewater treatment plants undertake operational improvements to increase nutrient removal in response to state program incentives. Through quantitative and qualitative analysis, this thesis found evidence of lowered nitrogen discharges in response to financial incentives presented by each states point source control programs at municipal wastewater treatment plants. Maryland achieves modest improvements at a subset of advanced treatment WWTPs as a result of financial incentives presented by the state's public subsidy program. Although Virginia advanced treatment plants operating within a nutrient trading program have little incentive to over-comply, there is some evidence of operational improvements at less advanced nitrogen removal plants
Master of Science

Due to more stringent regulations for secondary municipal wastewater treatment, municipalities are beginning to implement tertiary treatment in their wastewater treatment plants. Tertiary treatment would be the removal of either phosphorous or nitrogen or both from the wastewater before it is discarded from the plant. Biological treatment is becoming an increasingly popular process used to accomplish this extra removal. There are several processes available that will provide acceptable levels of biological nutrient and BOD removal from wastewater. Three well-known processes were considered in this study - the Modified Bardenpho Process, the Modified UCT Process and the A2/O Process. For each of these processes, 2 1evel fractional factorial designs along with least squares analysis were performed in order to determine the optimal operating variables (recycle rates and anaerobic, anoxic and aerobic zone retention times), with respect to the final nitrogen concentration, the final phosphorous concentration and a combination of the final nitrogen and phosphorous concentrations. The analyses were performed at 10°C and 20°C with low, medium and high primary effluent concentrations. Due to the complexity of the processes, lab scale experiments were not feasible. Therefore, a widely accepted calibrated biokinetic model (Activated Sludge Model No 2d) was used in a computer simulation program (GPS-X) to gather the necessary data for analysis. Actual plant data were used to test the validity of the simulation model with respect to organic and nitrogen removal. Using the published kinetic and stoichiometric parameters for both temperature levels, the Activated Sludge Model provided a good estimation of outlet concentration levels. It was found that all three biological nutrient removal (BNR) process were capable of achieving an effluent soluble phosphorous concentration below the required limit of 1 mgP/L at 10 and 20°C with low, medium and high primary effluent concentration when the effluent nitrogen concentration was neglected. Neither the Modified Bardenpho, the Modified UCT nor the A 2/O process were capable of producing an effluent with nitrogen concentrations below the required limit of 5 mgN/L at high primary effluent concentrations. The Modified Bardenpho and the Modified UCT processes were both successful in achieving a combined nitrogen and phosphorous removal below their regulatory limits for low primary effluent concentrations at 10 and 20°C. The Modified Bardenpho process, at 20°C with medium primary effluent concentrations, was found to achieve an effluent with nitrogen and phosphorous concentrations below 5 mgN/L and 1 mgP/L, respectively. After analyzing the effects of individual operating variables, it was found that the anoxic recycle for the Modified UCT process had an insignificant effect on total nitrogen (TN) and soluble phosphorous (sP) removals and did not need to be included in future experimental studies. All of the input variables to the MB and A2/O process proved to be somewhat significant and it is recommended that they be kept within future experimental designs. From this study it was found that both the MB and MUCT process are capable of achieving the TN, sP and cBOD5 removals that ROPEC requires. However only the MB process proved to be a robust system when subjected to storm conditions (i.e., peaks in influent flow rate) with respect to sP and cBOD5 removal. Neither the MB nor the MUCT process provided acceptable TN removals when subjected to storm conditions. It is recommended that ROPEC further evaluate the MB process as a possible means to achieve simultaneous cBOD5, TN and sP removal.

Despite the technology advancement, degradation of water quality due to stormwater continues to be a significant threat to the water and ecosystems due to the exponential growth of industries and agricultural enterprises that discharge stormwater. These anthropogenic activities are the sources of high nitrogen and phosphorus quantities in stormwater, which is responsible for eutrophication phenomena and deterioration of public health. Floating Treatment Wetlands (FTWs) are a potential solution to this problem. Both microcosm and mesocosm level studies were conducted for the effective removal of nutrients in stormwater wet detention ponds with different sorption media under varying nutrient concentrations and weather conditions. Water depth, percent area coverage of the FTWs and littoral zone emergent plants were varied in order to determine nutrient removal efficiency before implementing in an actual pond. Focus has also been placed on the observations of macrophyte-epiphyte-phytoplankton interactions in order to understand temporal characteristics of ecological phenomena. Water quality parameters included Total Nitrogen, Total Phosphorus, Orthophosphate, Nitrate-Nitrogen, and Ammonia-Nitrogen in addition to in-situ parameters such as pH, Dissolved Oxygen, Temperature and Chlorophyll-a. Results clearly indicate that an FTW filled with sorption media of 80% expanded clay and 20% tire crumb can significantly promote the biomass growth. Different levels of nutrient concentrations did affect the plants' growth and cold temperature in late winter was detrimental to growth. To make the system more viable irrespective of the seasonal weather conditions, the adoption of mixed vegetation is highly recommended in the FTWs implementation.; It is also recommended that, the positioning of the floating wetlands should not be in the vicinity of the outlet of the pond as assimilated nutrient under the mat might increase the nutrient concentration in the discharged water. Finally, One-way ANOVA test is performed to check whether or not these grouped microcosms and mesocosms with differing experimental setup can be deemed statistically significant.
ID: 030422696; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.Env.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 70-74).
M.S.
Masters
Civil, Environmental and Construction Engineering
Engineering and Computer Science

Bacterial populations proliferating in a pilot scale biological nutrient removal system (BNR) were studied. The objective of the research was to develop media and methods to identify bacterial populations in BNR systems. Samples were obtained from the last aerobic zone of a University of Cape Town (UCT)-type system. The most probable numbers (MPN) of bacteria in the samples were analyzed in liquid media containing volatile fatty acids as sole sources of carbon. Samples were also transferred to denitrification medium, and MPN's of denitrifiers were recorded. The growth in liquid medium was plated on solid medium. Gram-negative cultures were isolated and identified. The phosphorus-removal capacity of five isolates also was studied. The results indicated that several different genera of bacteria are involved in the removal of phosphorus in an operating BNR system. Four major groups of phosphorus storing bacteria, Aeromonas/Vibrio, coliforms, Pseudomonas spp and Acinetobacter spp, were recovered. The identification of cultures on denitrification medium also recovered Pseudomonas, Aeromonas, coliforms and Acinetobacter, indicating the overlap in the function of these genera. The phosphorus accumulations in three of the tested cultures showed accumulations in excess of 10 percent. The MPN's of bacteria in acetate and propionate media obtained using samples from the pilot scale BNR system and a full scale activated sludge system were statistically analyzed. The analyses showed significant differences between MPN in acetate and propionate medium using samples from the BNR system, whereas there were no significant differences in samples from the conventional activated sludge plant. The possibility of the application of these data in process control and modeling is proposed.
Ph. D.

This thesis discusses the mechanisms associated with the removal of organic matter, nitrogen and phosphorus in wastewater-fed high rate algae ponds (HRAP) designed to operate as triplicates. Research was conducted at the San Luis Obispo Water Reclamation Facility (SLOWRF) as a pilot-scale study of nine 30-square meter ponds one foot in depth. During period of study, triplicates were operated at hydraulic retention times (HRT) of 4, 3 or 2-days. Main objectives for the study were to determine minimum HRTs required to achieve secondary and tertiary treatment. Experimental conditions such as CO2 supplementation, nighttime aeration and operation of ponds in series were employed to evaluate optimal conditions for efficient nutrient removal. Ponds were continuously fed primary effluent with the following water quality characteristics: 5-day total biochemical oxygen demand (TBOD5) of 124mg/L, 5-day soluble carbonaceous biochemical oxygen demand of 67mg/L (scBOD5), total suspended solids (TSS) of 66mg/L, volatile suspended solids (VSS) of 65mg/L, total ammonia nitrogen (TAN) of 34mg/L-N, oxidized nitrogen of 1.1mg/L-N, total K̇jeldahl nitrogen (TKN) of 42mg/L-N and dissolved reactive phosphorus (DRP) of 3.3mg/L-P. Nutrient removal efficiencies were compared between summer months (April – October) and winter months (November – February). Average pond temperatures during summer and winter were 20.4 °C and 14.9 °C, respectively. Average TAN removal efficiencies of 2-day HRT ponds ranged from 62% in winter to 78% in summer. Operation of ponds at an increased 3-day HRTs resulted in corresponding seasonal increases of TAN removal by 14% and 12%. In 4-day HRT ponds operating in series after a 3-day HRT set, TAN removal efficiency was 98% in winter and 99% in summer. Aeration increased nitrification and nitrate concentrations in 2-day HRT ponds to10mg/L-N ± 4.4mg/L-N. DRP concentrations and BOD removal efficiencies within replicate ponds were similar throughout seasonality. DRP was 1.2mg/L-P ± 0.66mg/L-P at a 4-day HRT operating in series, 2.2mg/L-P ± 0.57mg/L-P at a 3-day HRT and 2.6mg/L-P ± 0.58mg/L-P at a 2-day HRT. Aeration had no measureable effect on BOD removal. BOD removal efficiency was 97% at a 4-day HRT in series with a 3-day HRT and 95% at 3-day and 2-day HRTs.

Shallow, mixed raceway ponds can be used to grow microalgae for the dual purposes of wastewater treatment and biofuel feedstock production. To improve the environmental sustainability of microalgae biofuels and to alleviate resource limitations, nutrients remaining after biofuel production should be recycled for additional cultivation. This thesis considers three topics: wastewater treatment by algae, nitrogen and phosphorus assimilation by algae, and algae cell disruption to facilitate nutrient recovery. The main experimental work was done in pilot raceway ponds growing polycultures of microalgae on clarified municipal wastewater. In addition, two lab-scale pretreatment technologies were tested for their ability to disrupt cells, as indicated by subsequent biomass organic nitrogen and particulate phosphorus degradation during sequential anaerobic and aerobic digestion. The two pretreatment technologies were sonication and high-pressure homogenization. The raceway pond research was conducted at the City of San Luis Obispo Water Resource Recovery Facility (WRRF). Nine 30-m2, 0.3-m deep raceway ponds were operated continuously from March 1, 2013 to August 31, 2014. The ponds were arranged in three sets of triplicates. One set was operated at a 2-day hydraulic residence time (HRT) on clarified wastewater throughout the study. A second set (“Round 1” of ponds-in-series) was operated at a 3-day HRT, also on clarified wastewater. Its effluent was clarified and then discharged into the third set (“Round 2” of ponds-in-series), which initially operated at a 4-day HRT but then later a 3-day HRT. The nutrient removal and assimilation data were compared seasonally—summer (March–October) and winter (November–February). The triplicate raceways operating at a 2-day HRT achieved average total ammonia nitrogen (TAN) removal efficiencies of 11% in the winter and 71% in the summer, while dissolved reactive phosphorus (DRP) removal remained similar throughout seasonality. In the first ponds-in-series experiment (3-day HRT followed by 4-day), average summer TAN removal efficiencies for Round 1 and 2 were 88% and nearly 100%, respectively. Round 1 and 2 average summer DRP removal efficiencies were 29% and 67%, respectively. The first ponds-in-series experiment was not conducted in the winter. In the second experiment, the Round 2 HRT was changed to 3 days. Average TAN removal efficiencies for Round 2 in the winter and summer were 88% and 100%, respectively. DRP removal for Round 2 increased from 38% in the winter to 66% in the summer. Total nitrogen (TN) mass balances on the raceway pond experiments were useful to illustrate the fate of influent nitrogen, including losses. In the first ponds-in-series experiment, 76% of the influent soluble nitrogen was converted to organic nitrogen by assimilation, while 6% of the influent ammonia was lost by volatilization. In the second ponds-in-series experiment, 81% of the influent soluble nitrogen was converted to organic nitrogen by assimilation and only 1% of the influent ammonia was lost by volatilization. The 2-day HRT raceway experiment achieved 41% conversion of influent soluble nitrogen to organic nitrogen by assimilation, with influent ammonia losses of 3% by volatilization. In addition to these pilot-scale raceway pond experiments, laboratory experiments were conducted on re-solubilization of algae biomass nutrients to support additional algae growth. Algae harvested from the pilot ponds was pre-treated with either sonication or high-pressure homogenization. The pretreated biomass was then subjected to anaerobic digestion and then aerobic digestion to increased nitrogen and phosphorus solubilization. The laboratory anaerobic digestion simulated pilot digestion, also conducted at the pilot facility, and the aerobic digestion was meant to simulate further re-solubilization that would occur when algae digestate was returned to the aerobic raceway ponds to promote further algae growth. Neither pre-treatment technologies had a significant impact on degradation of biomass organic nitrogen and particulate phosphorus compared to controls. It was found that simple anaerobic digestion followed by aerobic digestion resolubilized 90% of organic nitrogen and 50% of particulate phosphorus.

Urban stormwater runoff is a major concern in Australia and in other parts of the world, because of its potential severe, quantity and quality related impacts on the health of environmental water systems. Many stormwater quality improvement devices (SQ IDs) have been developed over time. Constructed wetlands are a relatively new SQID, and are the specific topic of this thesis. The construction of wetlands for stormwater quality improvement has been prompted by the effectiveness of natural wetlands in storing stormwater runoff during rainfall events and improving water quality during flow through the system during dry periods. However, like other ecosystems, wetlands are profoundly complex. Wetlands for stormwater quality improvement vary greatly in performance due to differences in design, climate, catchment characteristics and other factors. In particular, nutrient removal efficiencies vary widely among wetland systems. This is a result of the lack of understanding of fundamental aspects of these extremely complex, heterogeneous systems, and of phenomena responsible for nutrient removal. In particular how these are affected by environmental conditions and system design. This thesis investigated the performance of a constructed wetland treating stormwater runoff from an urban catchment. It aims to improve understanding of the performance of wetlands in removing nutrients from stormwater runoff, in a subtropical climate. A three-year-old wetland system (Keith Boden wetland) located in an urban catchment in Brisbane, Australia, was investigated over two distinct seasonal periods, autumn and summer. Water samples were collected at eight locations in different parts of the wetland. Additionally, sediment samples were taken on the last sampling date of the autumn sampling period. Results from this study showed that this wetland system was most effective and consistent in removing nitrate and orthophosphate during both seasons (autumn and summer). However, concentrations of both nitrate and orthophosphate were considerably lower within the wetland during summer. The removal of nitrate was mainly due to denitrification. The removal process for orthophosphate varied within the two sampling periods: Biological uptake of orthophosphate appeared to be high during the summer period. The processes of orthophosphate retention during the autumn sampling period were more difficult to understand and it was more likely that uptake of orthophosphate was overshadowed by the release of orthophosphate from the sediments. Other forms of nitrogen and phosphorus that were measured displayed variable behaviour within the wetland system. During summer vertical temperature and dissolved oxygen profiling showed stratification on some occasions. A detailed discussion of the methodology and results of this study highlighted the complexity of wetland systems and showed that any study of these systems is necessarily limited. Nonetheless, the experimental studies conducted as a part of this research have provided insights into the systems functioning and greater awareness of possible behaviours. This is important knowledge to aid the monitoring, design and application of wetlands as SQIDs.

Florida is surrounded by water, and its many internal lakes and rivers have long been recognized for their excellent fishing and boating. This notoriety draws land developers to the lake shores to establish residential and commercial infrastructure. This land development brings with it flood plain alteration, water level stabilization, and increased nutrients which cause adverse impacts to our lakes. In response, the United States Environmental Protection Agency (EPA) passed the Federal Clean Water Act (CWA) in 1972 which set the framework for the water quality standards for the entire United States. As a result of the CWA many point sources were eliminated, but in the process it became apparent that nonpoint source loads represented even more of a threat. To further study the physical and chemical characteristics of urban runoff the Nationwide Urban Runoff Program (NURP) was established in 1978. This research lead to a series of management options, named Best Management Practices (BMPs) which proposed various structural and non-structural methods to reduce nutrient loads. But the research and data collection on the effectiveness of these systems to remove nutrients is in its infancy. The main objective of this study was to generate accurate and effective water quality and water quantity data that future stormwater management decisions can be based upon. More specific, this study established automatic monitoring sites throughout the City of Kissimmee, Florida to determine the pollutant loadings into the tributaries of Lake Tohopekaliga. These monitoring sites are located such that inflows from outside the city limits can be isolated and external pollutant loads quantified. Also, additional internal monitoring sites were established to determine the pollutant loads of internal sections of the city. Data from these internal monitoring sites will also be used to determine the variable pollutant removal efficiencies and hydraulic fluctuations of natural, irregular riverine systems. The secondary objective of this study was to perform a pilot study using the discrete grab samples in tandem with the continuous hydraulic and hydrologic data from the monitoring stations. An existing lake within the project limits was chosen for the pilot study area. Monitoring stations are located at the influent and effluent sections of the lake which provided data on the hydraulic and hydrologic parameters. The pilot study determined the nutrient loads to and from the lake and checked for any seasonal variations in pollutant loading or removal efficiencies. For the purpose of this pilot study, only total nitrogen and total phosphorous were examined for two monitoring sites. The nutrient removal efficiency was performed using both the event mean concentration method and the summation of loads method to check for seasonal variation. There were no storm event concentrations available for used in this analysis, however, there were 25 discrete grab samples collected on a bi-monthly basis over a twelve month period. This data was used with corresponding five-minute rainfall and flow data from both the inflow and outflow points. The results of this study did not reveal any seasonal variation in the nutrient concentrations either flowing into or out from the lake. Although there were some relatively lower values in late spring, the concentration levels of total nitrogen did not seem to vary significantly from its mean value of 0.90 mg/l throughout the year. The concentration levels of total phosphorus did range from 0.02 mg/l to 0.48 mg/l, but not in relation to either season or flow volume fluctuations. The lake showed no net removals of total nitrogen and was actually found to be releasing total phosphorus to the downstream receiving waters. The findings of this study are limited due to the fact that the period of pilot study was only for twelve months and there were no rainfall events used in the analysis. Rainfall events are typically high sources of nutrient loads to a lake. The lower efficiencies were probably due to missing the actual higher nutrient load concentrations during the rainfall event. However, even considering the lack of event data, the nutrient removal efficiency for the pond was still low. This analysis did serve well as a basis for performing future analysis once additional data, including rainfall events, has been collected.
M.S.C.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering MSCE

Biological nutrient removal has been studied and applied for decades in order to remove nitrogen and phosphorus from wastewater. However, more anthropogenic uses and the continued demand for water have forced the facilities to operate at their maximum capacity. Therefore, the goal of this thesis is to obtain more compact systems for nutrient removal from domestic wastewater. In this sense, optimization and long-term stabilization of high volume exchange ratios reactors, treating higher volumes of wastewater, have been investigated. With the same target, aerobic granular sludge was proposed as a reliable alternative to reduce space and increase loading rates in treatment plants. However, the low organic loading rate from low-strength influents (less than 1 Kg COD•m-3d-1) results in slower granular formation and a longer time to reach a steady state. Because of that, different methodologies and operational conditions were investigated in order to enhance granulation and nutrient removal from domestic wastewater.
L’estudi de l’eliminació biològica de nutrients s’ha dut a terme durant dècades. Tot i això, la influencia de l’home i l’augment de la demanda d’aigua han forçat a les instal•lacions a treballar a la seva capacitat màxima. Així, l’objectiu de la tesi és obtenir sistemes més compactes per a l’eliminació de nutrients de les aigües residuals. En aquest sentit, s’ha investigat l’optimització i estabilització de reactors amb alts volums d’intercanvi, tractant més aigua. Amb el mateix objectiu, el fang granular aeròbic va ser proposat com una alternativa fiable per tal de reduir l’espai i incrementar les càrregues de les depuradores. Tot i això, la granulació amb influents de baixa càrrega (menors a 1 Kg dQO•m-3d-1) resulta més lenta i més dificultosa alhora d’obtenir l’estat estacionari. Per aquesta raó es van investigar diferents metodologies i condicions d’operació per tal de millorar la granularció i l’eliminació de nutrients de les aigües urbanes.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.
Includes bibliographical references (leaf 65).
by Haseeb Mahmood and Carolyn E. Metzger.
M.Eng.

The main objective of the research was to investigate the effect of influent organic compounds on the performance of biological nutrient removal system. To carry out the investigation, a pilot plant system was designed and constructed. The system was operated as a UCT process at an influent flow rate of 0.15 liters/minute and a sludge age of 13 days. The influent wastewater was domestic sewage. Excess biological phosphorus removal and steady-state conditions were established before making experimental measurements, or adding supplemental substrate. The effects of separate addition of formic, acetic, propionic, butyric, isobutyric, valeric, and isovaleric acid, plus glucose, addition on phosphorus release under anaerobic conditions, and phosphorus uptake under aerobic conditions, were studied. The effects of the organic acid additions on the removal of nitrogen and COD, and changes in SOUR, MLVSS, and metals such as iron, magnesium, calcium and potassium, were also studied. In all experiments, the specific substrate was added continuously to the first anaerobic reactor for three days at an influent concentration of 100 mg COD/liter. Samples were collected from each reactor at the end of the addition period and analyzed for orthophosphate, nitrate, nitrite, sulfate, volatile fatty acids, COD, MLVSS, pH and metals. All added substrates, except formic acid and dextrose, caused significant increases in phosphorus release in the anaerobic stage, and phosphorus uptake, in the aerobic stage, and consequently, an increase in phosphorus removal efficiency. The molar ratios of phosphorus release to volatile fatty acid added obtained for propionic acid, acetic acid, butyric acid, and valeric acid were 0.44, 0.77, 0.78, and 1.72 respectively. However, on a COD basis, the greatest ratios of mg phosphorus released to mg COD utilized was produced by the addition of acetic acid (0.37) and valeric acid (0.19). It was also found that the branched organic acids, isobutyric and isovaleric, caused more phosphorus release in the anaerobic stage and better phosphorus removal efficiencies as compared with the nonbranching forms of the same organic acids. The molar ratios of phosphorus release for these two acids were 0.8 and 2.3, respectively, and on a COD basis were 0.16 and 0.25. For engineering applications, it is suggested by this research that at least 20 mg COD equivalent of acetic acid is needed for the removal of I mg phosphorus. The results obtained by this investigation were consistent with the hypothesis proposed by Marais et al., 1983. The most recent biochemical models, proposed by Comeau et al., 1986 and Wentzel et al., 1986, were also tested using the data collected in the present investigation. Both models, in most cases, overestimated the ratios of phosphorus release to volatile fatty acid utilized. A speculative model for anaerobic metabolism by poly-p bacteria of volatile fatty acids which contain both odd and even numbers of carbon atoms was proposed. All added substrates produced no effect on both COD and TKN removals. Metal releases were found to correlate with the amount of phosphorus release.
Ph. D.

Actualment, la legislació ambiental ha esdevingut més restrictiva pel que fa a la descàrrega d'aigües residuals amb nutrients, especialment en les anomenades àrees sensibles o zones vulnerables. Arran d'aquest fet, s'ha estimulat el coneixement, desenvolupament i millora dels processos d'eliminació de nutrients.
El Reactor Discontinu Seqüencial (RDS) o Sequencing Batch Reactor (SBR) en anglès, és un sistema de tractament de fangs actius que opera mitjançant un procediment d'omplerta-buidat. En aquest tipus de reactors, l'aigua residual és addicionada en un sol reactor que treballa per càrregues repetint un cicle (seqüència) al llarg del temps. Una de les característiques dels SBR és que totes les diferents operacions (omplerta, reacció, sedimentació i buidat) es donen en un mateix reactor.
La tecnologia SBR no és nova d'ara. El fet, és que va aparèixer abans que els sistema de tractament continu de fangs actius. El precursor dels SBR va ser un sistema d'omplerta-buidat que operava en discontinu. Entre els anys 1914 i 1920, varen sorgir certes dificultats moltes d'elles a nivell d'operació (vàlvules, canvis el cabal d'un reactor a un altre, elevat temps d'atenció per l'operari...) per aquests reactors. Però no va ser fins a finals de la dècada dels '50 principis del '60, amb el desenvolupament de nous equipaments i noves tecnologies, quan va tornar a ressorgir l'interès pels SBRs. Importants millores en el camp del subministrament d'aire (vàlvules motoritzades o d'acció pneumàtica) i en el de control (sondes de nivell, mesuradors de cabal, temporitzadors automàtics, microprocessadors) han permès que avui en dia els SBRs competeixin amb els sistemes convencional de fangs actius.
L'objectiu de la present tesi és la identificació de les condicions d'operació adequades per un cicle segons el tipus d'aigua residual a l'entrada, les necessitats del tractament i la qualitat desitjada de la sortida utilitzant la tecnologia SBR. Aquestes tres característiques, l'aigua a tractar, les necessitats del tractament i la qualitat final desitjada determinen en gran mesura el tractament a realitzar. Així doncs, per tal d'adequar el tractament a cada tipus d'aigua residual i les seves necessitats, han estat estudiats diferents estratègies d'alimentació.
El seguiment del procés es realitza mitjançant mesures on-line de pH, OD i RedOx, els canvis de les quals donen informació sobre l'estat del procés. Alhora un altre paràmetre que es pot calcular a partir de l'oxigen dissolt és la OUR que és una dada complementària als paràmetres esmentats.
S'han avaluat les condicions d'operació per eliminar nitrogen d'una aigua residual sintètica utilitzant una estratègia d'alimentació esglaonada, a través de l'estudi de l'efecte del nombre d'alimentacions, la definició de la llargada i el número de fases per cicle, i la identificació dels punts crítics seguint les sondes de pH, OD i RedOx.
S'ha aplicat l'estratègia d'alimentació esglaonada a dues aigües residuals diferents: una procedent d'una indústria tèxtil i l'altra, dels lixiviats d'un abocador. En ambdues aigües residuals es va estudiar l'eficiència del procés a partir de les condicions d'operació i de la velocitat del consum d'oxigen. Mentre que en l'aigua residual tèxtil el principal objectiu era eliminar matèria orgànica, en l'aigua procedent dels lixiviats d'abocador era eliminar matèria orgànica i nitrogen.
S'han avaluat les condicions d'operació per eliminar nitrogen i fòsfor d'una aigua residual urbana utilitzant una estratègia d'alimentació esglaonada, a través de la definició del número i la llargada de les fases per cicle, i la identificació dels punts crítics seguint les sondes de pH, OD i RedOx.
S'ha analitzat la influència del pH i la font de carboni per tal d'eliminar fòsfor d'una aigua sintètica a partir de l'estudi de l'increment de pH a dos reactors amb diferents fonts de carboni i l'estudi de l'efecte de canviar la font de carboni.
Tal i com es pot veure al llarg de la tesi, on s'han tractat diferents aigües residuals per a diferents necessitats, un dels avantatges més importants d'un SBR és la seva flexibilitat.
Actualmente, la legislación ambiental se ha convertido más restrictiva por lo que concierne al vertido de aguas residuales con nutrientes, especialmente en las llamadas áreas sensibles o zonas vulnerables. A partir de este hecho, se ha estimulado el conocimiento, desarrollo y mejora de los procesos de eliminación de nutrientes.
El Reactor Discontinuo Secuencial (RDS) o Sequencing Batch Reactor (SBR) en inglés, es un sistema de tratamiento de fangos activados que opera mediante un procedimiento de llenado-vaciado. En este tipo de reactores, el agua residual es adicionada en un solo reactor que trabaja por cargas repitiendo un ciclo (secuencia) a lo largo del tiempo. Una de les características de los SBR es que todas las diferentes operaciones (llenado, reacción, sedimentación y vaciado) se dan en el mismo reactor.
La tecnología SBR no es nueva. De hecho, apareció antes que el sistema de tratamiento continuo de fangos activados. El precursor de los SBR fue un sistema de llenado-vaciado que operaba en discontinuo. Entre los años 1914 y 1920, surgieron ciertas dificultades muchas de ellas a nivel de operación (válvulas, cambios de caudal de un reactor a otro, elevado tiempo de atención por parte del operario...) para estos reactores. Pero no fue hasta finales de la década de los '50 principios de los '60, con el desarrollo de los nuevos equipamientos y las nuevas tecnologías, cuando volvió a resurgir el interés en los SBRs. Importantes mejoras en el campo de los suministro de aire (válvulas motorizadas o de acción neumática) y en el de control (sondas de nivel, medidores de caudal, temporizadores automáticos, microprocesadores) han permitido que hoy en día los SBRs compitan con los sistemas convencionales de fangos activados.
El objetivo de la presente tesis es la identificación de las condiciones de operación adecuadas para un ciclo según el tipo de agua residual en la entrada, las necesidades del tratamiento y la calidad deseada de la salida utilizando la tecnología SBR. Estas tres características, el agua a tratar, las necesidades del tratamiento y la calidad final deseada determinan en gran medida el tratamiento a realizar. Así pues, para poder adecuar el tratamiento a cada tipo de agua residual y a sus necesidades, han sido estudiados diferentes estrategias de alimentación.
El seguimiento de los cambios de las medidas en línea de pH, OD y RedOx proporciona información sobre el proceso. A su vez, otro parámetro que se puede calcular a partir del OD es la OUR que también da información del proceso.
Se han evaluado las condiciones de operación para eliminar nitrógeno de una agua residual sintética utilizando una estrategia de alimentación escalonada, a partir del estudio del efecto del número de alimentaciones, la definición de la longitud y el número de fases por ciclo, y la identificación de los puntos críticos siguiendo las sondas de pH, OD y RedOx.
Se ha aplicado la estrategia de alimentación escalonada a dos aguas residuales diferentes: una procedente de una industria textil y la otra, de los lixiviados de un vertedero. En las dos aguas residuales se estudió la eficiencia del proceso a partir de las condiciones de operación y de la velocidad de consumo de oxigeno. Mientras que en el agua residual textil el principal objetivo era eliminar materia orgánica, en el agua procedente de los lixiviados del vertedero era eliminar materia orgánica y nitrógeno.
Se han evaluado las condiciones de operación para eliminar nitrógeno y fósforo de una agua residual urbana utilizando una estrategia de alimentación escalonada, a partir del estudio de la definición de la longitud y el número de fases por ciclo, y la identificación de los puntos críticos siguiendo las sondas de pH, OD y RedOx.
Se han analizado la influencia del pH y la fuente de carbono para eliminar fósforo de un agua sintética a partir del estudio del incremento de pH en dos reactores con diferentes fuentes de carbono y el estudio del efecto de cambiar la fuente de carbono.
Como se puede apreciar a lo largo de la tesis, donde se han tratado diferentes aguas residuales para a diferentes necesidades, una de las ventajas más importantes de los SBR es su flexibilidad.
Nowadays, environmental legislation has become more restricted in the nutrient wastewater discharge, especially in the sensitive areas and vulnerable zones. So, many studies have been stimulated on the understanding, developing and improving the biological nutrient removal processes.
The Sequencing Batch Reactor (SBR) is a fill-and-draw activated sludge system for wastewater treatment. In this system, wastewater is added to a single reactor which operates in a batch treatment mode repeating a cycle (sequence) continuously. All the operations (fill, react, settle and draw) are achieved in a single batch reactor.
SBR technology is not new. In fact, it precedes the use of continuous flow activated sludge technology. The precursor to this was a fill-and-draw system operated on batch, similar to the SBR. Between 1914 and 1920, many difficulties were associated with operating these fill-and-draw systems, most resulting from the process valving required to switch flow from one reactor to another, operator attention required. Interest in SBRs was revived in the late 1950s and early 1960s, with the development of new equipment and technology. Improvements in aeration devices (i.e. motorized valves, pneumatically actuated valves) and controls (level sensors, flowmeters, automatic timers, microprocessors) have allowed SBRs to successfully compete with conventional activated sludge systems.
The aim of this thesis consists in the identification of suitable operation conditions for a cycle according to kind of influent wastewater, treatment requirements and effluent quality using a SBR technology. The influent wastewater, treatment requirements and effluent quality desire determinate in great measure the treatment to realize. So, different studies have been carried out in order to obtain a suitable treatment for each wastewater and requirement using a step-feed strategy.
By means of on-line pH, DO and ORP measurements are possible follow the status of the process. At the same time another parameter, that complements all these, is the OUR calculated through DO dada.
Evaluation the operation conditions for nitrogen removal using a step-feed strategy for a synthetic wastewater through the study of the effect of number of filling events, the definition of the length and number of phases for a cycle, and the identification of the critical points following the pH, DO and ORP sensors.
Application of the step-feed strategy in two different industrial wastewaters: textile wastewater and landfill leachate wastewater. In both wastewaters, the efficiency has been studied through the operational conditions and oxygen uptake rate. While in the textile wastewater the main objective was only organic matter removal, in the landfill leachate wastewater was carbon and nitrogen removal.
Evaluation of the operation conditions for nitrogen and phosphorus removal using a step-feed strategy for an urban wastewater through, the definition of the number and length of phases for a cycle, and the identification of the critical points following the pH, DO and ORP sensors.
Influence of pH and carbon source in phosphorus removal using synthetic wastewater through the study of pH increase in two different carbon sources and the effect of change of carbon source.
As it can be observed in this thesis, where it is treated different wastewaters for different requirements, one of the main advantages of the SBR is its flexibility.

In the last decades, the awareness of environmental issues has increased in society considerably. There is an increasing need to improve the effluent quality of domestic wastewater treatment processes. This thesis describes the application of the Sequencing Batch Reactor (SBR) technology for Biological Nutrient Removal (BNR) from the wastewater. In particular, the work presented evolves from the nitrogen removal to the biological nutrient removal (i.e. nitrogen plus phosphorous removal) with special attention to the operational strategy design, the identification of possible reactor cycle controls or the influent composition related to the process efficiency. In such sense, also the use of ethanol as an external carbon (when low influent Carbon:Phosphorus (C:P) or Carbon:Nitrogen (C:N) ratios are presented) are studied as an alternative to maintain the BNR efficiency.

The primary objective of this research was to remove recalcitrant nutrients from anaerobically digested sludge dewatering centrate. Recalcitrant nutrients are defined as small (<0.45 µm) particles or molecules containing bound phosphorus and/or nitrogen and are commonly referred to as non-reactive dissolved phosphorus and dissolved organic nitrogen. Recalcitrant nutrients will persist through wastewater treatment processes and contaminate treated wastewater. The situation is complicated by anaerobic digestion of solid residuals, which load a wastewater treatment facility with more recalcitrant nutrients through internal sidestream recirculation loops. Recalcitrant nutrient treatment may be required for wastewater treatment facilities looking to use anaerobic digestion for energy (biogas) recovery and meet stringent nutrient discharge requirement. A struvite precipitation methodology is proposed where salt crystals are encouraged to ballast colloidal particles through heterogeneous nucleation. Four biologically unique dewatering centrates were used to test the precipitation methodology on the variety of anaerobic digester configurations that can be expected from municipal wastewater treatment plant. The effect of digestion sludge retention time (2 day, 20 day) and digestion temperature (35°C, 55°C) on the removal of dissolved unreactive phosphorus and nitrogen was monitored. Averaged across all four centrates, the precipitation methodology resulted in dissolved unreactive phosphorus and nitrogen removal of 82.4% and 66.6%, respectively. Antimicrobial contaminants (triclosan, triclocarban) were observed in the precipitates at minute concentrations (<18 ng/g-dry solids). Therefore, heterogeneous struvite nucleation can provide a means of recalcitrant nutrient treatment and reactive nutrient recovery without the micropollutant burden of biosolids land application.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

With the aim of mitigating membrane fouling, an electrocoagulation (EC) based electrokinetic membrane bioreactor (EMBR) was developed and operated with real municipal wastewater under low temperatures. Both batch tests and continuous EMBR experiments demonstrated the significant advantages in membrane fouling reduction over the conventional antifouling strategies, ushering its potential applications as an attractive hybrid MBR technology for decentralized wastewater treatment in remote cold regions. The main research observations and findings could be summarized as follows: (1). Effective membrane fouling mitigation at low temperatures was due to destruction of extracellular polymeric substances (EPS) and subsequent reduction of the biocake resistance. The transmembrane pressure (TMP) increased at a much slower rate in EMBR and the filtration resistance was about one third of the control MBR prior to chemical cleaning cycle; (2). A new membrane parameter, the specific fouling rate (SFR) was proposed, relating the fouling rate with permeate flux and temperature-dependent viscosity. Pore clogging and biocake resistances were quantified for the first time with the same membrane module and operating conditions as in regular MBR, rather than resorting to the use of batch filtration setups; (3). The floc size in EMBR did not increase as a result of the air scouring shear force and decrease in the extracellular polymeric substances (EPS); (4). When current intensity was less than 0.2 A, polarity reversal had minimal impact on electrode passivation reduction due to insignificant hydrogen yield, however, if current intensity was above 0.2 A, frequent polarity reversal (< 5 min per cycle) was detrimental to electrode passivation if no sufficient mixing was provided; (5). Viability of the microorganisms in the EMBR system was found to be dependent on duration of the current application and current density. The bacterial viability was not significantly affected when the applied current density was less than 6.2 A/m2; (6). Significant abiotic ammonification was found in electrocoagulation (EC). DO in the treated liquid was depleted within an hour, under the anaerobic condition in EC, nitrate was chemometrically reduced to ammonium following a two-step first order reaction kinetics. Aeration (DO > 2 mg/L) was shown effective in suppressing abiotic ammonification; (7). Magnetic resonance imaging (MRI) technology was used for the first time as an in-situ non-invasive imaging tool to observe membrane fouling status in an EMBR.
October 2016

Urbanisation, associated with the construction of ‘hard' impermeable surfaces such as roofs and roads, results in increased stormwater runoff peak flows and volumes and their associated pollutants into downstream receiving waters compared with the pre-development state unless mitigated through Sustainable Drainage Systems (SuDS). Permeable Pavement Systems (PPS), one of the source control options in SuDS suite, are able to control stormwater runoff and reduce the discharge of pollutants (Armitage et al., 2013). Urban runoff typically includes sediment, trash, heavy metals, organic matter, hydrocarbons and nutrients. PPS are able to remove a sizeable proportion of these through sedimentation, filtration, adsorption and biodegradation. The most commonly used PPS in South Africa are Permeable Interlocking Concrete Pavements (PICP) which comprise concrete pavers laid on selected stone layer works with surface infiltration enabled by the presence of carefully designed openings between the pavers filled with fine stone. The treatment performance of PICP systems appear to depend on various factors such as: the layout of the pavers; the size and condition of the stone aggregates; the presence and location of any geotextiles; the type of outlet; and the time period between rain events. While some research on the treatment of stormwater by PICP has been published, not enough is known about the relative performance of different PICP designs. This dissertation describes an investigation on the performance of 10 different PICP systems constructed in the civil engineering laboratory at the University of Cape Town (UCT) for the treatment of various nutrients (ammonia-nitrogen, orthophosphate-phosphorus and nitrate-nitrogen) commonly found in stormwater runoff. Ten experimental cells each housing a different permeable pavement design were constructed in the NEB laboratory at the UCT. Infiltration tests (ASTM C1781) were first conducted to test the hydrological performance of each of the PICP cell. This was followed by ‘clean water' tests to establish the ‘base-line' pollutant values prior to the additional of any pollutants. Finally, typical Cape Town rainfall events were simulated using a synthetic stormwater mixture containing representative nutrients concentrations to test the treatment efficacy for each of the permeable pavement systems over the period of two years with intermittent dry and wet periods. The influent and effluent from all ten experimental cells were periodically collected and analyzed for pH, temperature, electrical conductivity and the effluent concentrations of ammonia-nitrogen, orthophosphate-phosphorus, nitrite-nitrogen and nitratenitrogen. It was found that there is a reduction of ammonia-nitrogen for all experimental cells ranged from 27.5% to 78.7% compared with the average of 63.7% removal rate from other studies. However, the reduction in the ammonia-nitrogen effluent concentrations may not be true removal as the ammonia-nitrogen may have been converted into nitrite-nitrogen or nitrate-nitrogen through the nitrification process. It was also found that: the cells with geotextiles had higher ammonia-nitrogen reduction than those cells without; the cells with washed aggregates had higher ammonia-nitrogen reduction than those cells with unwashed aggregates; and the cell with a raised outlet (creating a ‘sump' in the underlying stone aggregate) had the highest ammonia- nitrogen reduction of all. The orthophosphate-phosphorus effluent concentrations ranged from 37% orthophosphate-phosphorus addition to 11% orthophosphate-phosphorus reduction compared with the average of 47.7% removal rate of orthophosphate-phosphorusin other studies. The presence of geotextile resulted in higher orthophosphate-phosphorus removal efficiencies than those cells without; the cells with washed aggregates had higher orthophosphate-phosphorus removal efficiency than those cells with unwashed aggregates. The cell with an elevated outlet (sump) had the least orthophosphate-phosphorus removal efficiency. In addition, it was found that all the experimental cells added significant quantities of nitrates having nitrate-nitrogen addition ranging from 160% to 2580% which may be due to the nitrification process of ammonianitrogen (NH3) to nitrate-nitrogen (NO3 - ). The cell with the raised outlet had the highest nitratenitrogen addition which can be explained by its highest ammonia-nitrogen removal efficiency through the nitrification process. It was also found that the presence of geotextile has a negative impact on the nitrate-nitrogen removal efficiencies, possibly because geotextiles provide a habitat for the microbes that encourage nitrification. The nitrification process, promoting the reduction in ammonia-nitrogen effluent concentrations and the increase in nitrate-nitrogen effluent concentrations occurs when the pH is within the optimum range of 7.6-8.8 for growth of nitrifying bacteria, Lower pH results in higher nitrate-nitrogen concentrations. It was also found that the electrical conductivity – a measure of ionic strength – strongly depends on the length of the periods between rainfall ‘seasons'; it decreases rapidly during wet periods and increases during dry periods. A field testing was also carried out on the New Engineering Building (NEB) parking lot at the UCT to confirm the true treatment performance of PPS. The results show the PICP are efficiently removing TSS, ammonia-nitrogen and orthophosphate-phosphorus. The PICP with geotextile was found to have positive impact on TSS, ammonia-nitrogen and orthophosphatephosphorus removal than the one without. It was also found the presence of geotextile has negative impact on nitrate-nitrogen removal, with lower pH resulting in higher nitrate-nitrogen concentrations which aggress the previous laboratory findings.

Stormwater runoff is a known pollutant source capable of causing surface water degradation, especially in highly populated areas such as Central Florida. Wet detention ponds manage this stormwater, but most of the ponds do not remove enough nutrients, specifically nitrogen and phosphorus, to meet TMDL regulations. This research provides a possible addition to a detention pond in Seminole County, Florida using a Chamber Upflow Filter and Skimmer (CUFS), which can increase the removal of phosphorus and nitrogen by the system. Water enters the system through the skimmer, which floats on the surface of the detention pond. It travels from the skimmer to the bottom of the chamber, where heavier particles settle out before entering the upflow filter. The upflow filter contains twenty-four inches of Black and GoldTM media to remove nitrogen and phosphorus under anoxic conditions. Water flows up through the filter and out of the system, and eventually travels to Lake Jesup, a eutrophic lake. A total of twenty-eight storm events and seven baseflows were sampled from the site in Seminole County, and ten storm events were sampled from a pilot study CUFS. The results of this research show significant reductions by the Seminole County CUFS in turbidity, orthophosphorus, total phosphorus, and total suspended solids when the means were compared at a 95% confidence interval. Reductions also occurred for total nitrogen, but could not be proved by the mean comparison. The pilot scale application of the CUFS significantly reduced total nitrogen at a 95% confidence interval.
M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engr MSEnvE

Biological nutrient removal (BNR) activated sludge systems (designed and operated with an additional function of biologically removing nitrogen and phosphorus) produce a waste activated sludge (WAS) that is rich in nitrogen (N) and phosphorus (P). When digested, this nitrogen and phosphorus are released, producing a dewatering liquor high in ammonia or nitrate and phosphate. Not only does this dewatering liquor need to be treated, but the phosphate also precipitates in the digester and surrounding pipework, resulting in loss of digester capacity and pipe blockages. This investigation studies anoxic-aerobic digestion (aerobic digestion with intermittent aeration), as an alternative digestion of BNR WAS. Aerobic digestion is simple to operate – being an extension of the activated sludge process, requiring aeration and limited recycling. This compared with anaerobic digestion which is complex to operate requiring airtight containers with fire risk, heating and much recycling. In anoxic-aerobic digestion, the nitrogen is removed by nitrification-denitrification, which has the added advantages of reducing the digester's oxygen demand and recovering some of the alkalinity lost in nitrification. Phosphate is precipitated in the digester - a convenient location. This results in a digester dewatering liquor low in nitrogen and phosphorus (<5 mgNH₄-N/l, <15 mgNO₃- N/l and 20 to 30 mgPO₄-P/l) that can be returned to the activated sludge plant without overloading it.

L’eliminació biològica de nutrients (EBN) a les estacions depuradores d’aigües residuals (EDARs) es considera el procés més rentable y mediambientalment més respectuós per a prevenir l’eutrofització i complir amb els cada cop més restrictius límits d’abocament. L’eliminació biològica de nitrogen (N) ha estat àmpliament estudiada i implementada en nombroses EDARs, tant urbanes com industrials. Contràriament, per a l’eliminació biològica de fòsfor, P, (procés EBPR) no existeixen encara molt exemples de la seva aplicació a escala real, principalment degut a l’aparició de fallades no esperades quan s’integrà amb l’eliminació biològica de N. La presència de nitrat a la fase anaeròbia es considera la principal causa d’aquestes fallades i, tot i la seva importància, els motius que les provoquen no es coneixen en profunditat. La hipòtesi més estesa assenyala que la presència de nitrat en condicions anaeròbies provoca la competència per la font de carboni (DQO) entre els organismes desnitrificants i els acumuladors de P (PAO). No obstant això, l’experiència en plantes reals indica que aquesta hipòtesi no és capaç de descriure l’elevada pèrdua real d’activitat EBPR tenint en compte la quantitat de nitrat present a la fase anaeròbia. Aquesta tesi té com a objectiu entendre els motius subjacents a aquesta perduda d’activitat EBPR i proposar alternatives per a minimitzar les seves causes. Per tal de fer front a aquest objectiu, des de diferents punts de vista, s’han utilitzat diferent eines: modelització, anàlisis microbiològics, optimització multi-criteri, anàlisis multivariable, operació en planta pilot y control de processos. Les principals fites assolides en aquest treball es resumeixen a continuació. Per una banda, es va observar que el contingut en matèria orgànica de l’afluent i la naturalesa d’aquesta són paràmetres clau per entendre la competència entre els organismes desnitrificants i els PAO. A partir de les dades experimentals es pot concloure que quan l’afluent conté principalment àcids grassos volàtils, els PAO són capaços de guanyar la competència per la font de carboni. Contràriament, els organismes desnitrificants es troben afavorits quan es tracta de fonts de carboni més complexes. Per l’altra banda, també es va estudiar l’ús diferents estratègies de control per tal de reduir la pèrdua de EBPR. Així mateix, es va demostrar com la optimització multi-criteri de les consignes dels controlador pot millorar l’operació d’una EDAR, no només reduint els costos d’explotació, sinó que també obtenint un efluent altament clarificat i amb un baix risc de desenvolupar problemes d’origen microbiològic (creixement excessiu de bactèries filamentosos o desnitrificació al decantador secundari). A més, les consignes optimitzades van afavorir el procés EBPR reduint l’entrada de nitrat a la fase anaeròbia. L’addició controlada de glicerol cru (subproducte del biodiesel) va ser provada amb èxit com alternativa per a reduir la competència entre els PAO i els organismes desnitrificants i, alhora, controlar el contingut de P en l’efluent. També, es va desenvolupar un model bioquímic per tal de descriure les dades experimentals obtingudes i per a dissenyar l’estratègia de control, que posteriorment va ser validada a la planta pilot. Malauradament, l’ús de fonts de carboni externes no és rentable a escala real i, per tant, també es va dissenyar i avaluar, in-silico, una nova estratègia de control per a millorar l’eliminació de P sense la necessitat d’afegir font de carboni o agents precipitants. El principi bàsic d’aquesta estratègia és desviar la DQO disponible cap al procés EBPR, en detriment del procés de desnitrificació (major concentració de nitrat en l’efluent), però sempre respectant els límits d’abocament. Finalment, també es va estudiar la importància d’estendre els models bioquímics existents per tal de millorar la simulació dels processos d’eliminació biològica de N i evitar la simulació de pèrdues irreals d’activitat EBPR. D’aquesta manera, es van incloure i estudiar conceptes com la nitrificació/desnitrificació en dos passos o la inclusió de sedimentador reactius.
La eliminación biológica de nutrientes (EBN) en estaciones depuradoras de aguas residuales (EDARs) se considera el proceso más rentable y medioambientalmente más respetuoso para prevenir la eutrofización y cumplir con los cada vez más estrictos límites de vertido. La eliminación biológica de nitrógeno (N) ha sido ampliamente estudiada e implementada con éxito en numerosas EDARs, tanto urbanas como industriales. Contrariamente, para la eliminación biológica de fósforo, P, (proceso EBPR) no existen aun muchos ejemplos de su aplicación a escala real, principalmente debido a la aparición de fallos inesperados cuando se integra con la eliminación biológica de N. La presencia de nitrato en la fase anaerobia se considera la principal causa de estos fallos y, a pesar de su importancia, los motivos que los desencadenan no se conocen perfectamente. La hipótesis más extendida apunta que la presencia de nitrato en condiciones anaerobias provoca la competencia por la fuente de carbono (DQO) entre los organismos desnitrificantes comunes y los acumuladores de P (PAO). Sin embargo, la experiencia en plantas reales indica que esta hipótesis no es capaz de describir la elevada pérdida real de EBPR considerando la cantidad de nitrato en la fase anaerobia. Esta tesis pretende estudiar los motivos subyacentes a esta pérdida de actividad EBPR y proponer alternativas para minimizar sus causas. Para abordar este objetivo desde diferentes puntos de vista, se han utilizado diferentes herramientas: modelización, análisis microbiológicos, optimización multi-criterio, análisis multivariable, operación en planta piloto y control de procesos. Los mayores logros conseguidos se resumen a continuación. Por un lado, se observó que el contenido en materia orgánica del afluente y la naturaleza de la misma son parámetros clave para entender la competencia entre los organismos desnitrificantes y los PAO. A partir de los datos experimentales se puede concluir que cuando el afluente está formado principalmente por ácidos grasos volátiles, los PAO son capaces de ganar la competencia por la fuente de carbono. Contrariamente, los organismos desnitrificantes son favorecidos cuando se trata de fuentes de carbono más complejas. Por otro lado, se estudió el uso de diferentes estrategias de control para reducir la pérdida de actividad EBPR. Asimismo, se demostró como la optimización multi-criterio de las consignas de los controladores puede mejorar la operación de una EDAR, no sólo reduciendo los costes de explotación, sino también obteniendo un efluente altamente clarificado y un bajo riesgo de desarrollar problemas de origen microbiológico (crecimiento excesivo de bacterias filamentosas o desnitrificación en el decantador secundario). Además, las consignas optimizadas favorecieron el proceso EBPR reduciendo la entrada de nitrato a la base anaerobia. La adición controlada de glicerol crudo (subproducto del biodiesel) fue probada con éxito como alternativa para reducir la competencia entre los PAO y los organismos desnitrificantes por la fuente de carbono y así, controlar el contenido de P en el efluente. Se desarrolló un modelo bioquímico para describir los datos experimentales obtenidos y para diseñar la estrategia de control, posteriormente validada en planta piloto. Sin embargo, el uso de fuentes de carbono externas no es rentable a escala real y, por tanto, también se desarrolló y evaluó in-silico una nueva estrategia de control para mejorar la eliminación de P sin la necesidad de añadir fuente de carbono o agentes precipitantes. El principio básico de la estrategia de control es desviar la DQO disponible hacia el proceso EBPR, en detrimento de la desnitrificación (mayor concentración de nitrato en el efluente), pero respetando limites de vertido. Finalmente, también se estudió la importancia de extender los modelos bioquímicos existentes para mejorar la simulación de los procesos de eliminación biológica de N y evitar la simulación de fallos irreales en el proceso EBPR. De este modo, se incluyeron y estudiaron conceptos como la nitrificación/desnitrificación en dos pasos o la inclusión de sedimentadores reactivos.
Considering biological nutrient removal (BNR) in WWTPs seems nowadays an obligated short-term aim because it is the most economical and environmental alternative to prevent eutrophication of water bodies and to meet the increasingly stricter discharge limits. Biological nitrogen (N) removal has been widely studied and successfully implemented in numerous WWTPs for treating both urban and industrial wastewater. On the other side, the so called Enhanced Biological Phosphorus (P) Removal (EBPR) process is not widely applied at full-scale yet because among other reasons, unpredictable EBPR failures have been reported when it is integrated with biological N removal. Nitrate recycling to the anaerobic phase is one of the most reported causes triggering this EBPR failure in real WWTPs and, despite its importance, the causes are not fully understood yet. A commonly accepted hypothesis is that nitrate presence triggers the competition for the carbon source between denitrifying ordinary heterotrophic organisms (OHO) and Polyphosphate Accumulating Organisms (PAO). However, experimental results show that this hypothesis fails to describe the magnitude of EBPR deterioration when the amount of nitrate entering the anaerobic zone is considered. This thesis aims at understating the EBPR deterioration due to nitrate presence in the anaerobic phase and studying alternatives to minimise the causes leading to this failure. Different tools have been used to study both topics from different points of view: modelling, microbial analysis, multi-criteria optimisation of the process performance, multivariate analysis, pilot plant operation and process control. As an overview, the main achievements of this thesis are next summarized. On the one hand, it was observed that the influent COD content and the nature of the carbon source are key parameters to understand the competition between OHO and PAO. The results obtained in pilot plant operation show that when influent COD was mainly composed by volatile fatty acids, PAO could outcompete OHO for the carbon source. Contrary, with more complex carbon sources, EBPR failed because denitrification process was favoured reducing COD available for PAO. On the other hand, the use of different control strategies has been assessed as a mitigating alternative to reduce EBPR failure. On this context, this thesis showed that multi-criteria optimisation of the controller setpoints can improve WWTP operation in terms of not only reducing the running costs but also ensuring low effluent discharges and low risk of developing microbiology-related failures (bulking or rising sludge). The optimised setpoints favoured P-removal process by reducing the nitrate load recycled to the anaerobic reactor. The controlled addition of crude-glycerol (biodiesel byproduct) was also demonstrated to be very useful to prevent nitrate-driven EBPR failure and for controlling effluent P concentration. A biochemical model was developed for describing the experimental data and to design the control strategy that was afterwards experimentally validated. However, the use of external carbon sources cannot be cost-effective at full-scale and thus, a novel control strategy aiming at improving P-removal without adding external carbon sources or chemicals for P precipitation was in-silico developed and evaluated. The principle behind this novel control strategy was diverting the available COD to P-removal and not to denitrification process (i.e. N in the influent increased), but always below the discharge limits. Finally, it was also studied the importance of new model extensions to correctly describe N removal. Hence, two-step nitrification/denitrification or reactive settler approaches should be considered to avoid unrealistic failure prediction of EBPR process.

[Truncated abstract] The use of constructed wetlands for tertiary purification of municipal wastewater has received increasing attention around the world because direct discharge of secondary-treated municipal wastewater to water bodies has caused eutrophication. Plant species selection and vegetation management may enhance nutrient removal efficiency in constructed wetlands. However, there is a lack of knowledge on the relations between plant growth and nutrient removal efficiency in constructed wetlands. The objective of this study is to better understand how plant growth and resource allocation are influenced by nutrients in wastewater and how nutrient removal efficiencies are affected by plant species and vegetation management. The preliminary experiment was conducted to select macrophytes, especially ornamental species, to grow in the wastewater in the wetland microcosms. Ten plant species, comprising six ornamental species: Alocasia macrorrhiza, Canna indica, Iris louisiana, Lythrum sp., Zantedeschia aethiopica, Zantedeschia sp., and four sedge species: Baumea articulate, Baumea juncea, Carex tereticaulis and Schoenoplectus validus, were planted in the wetland microcosms and fed a simulated wastewater solution in the concentrations similar to the secondary-treated municipal wastewater. C. indica has shown vigorous and healthy growth, and a relatively high potential of rooting-zone aeration and nutrient removal efficiency. B. articulata and S. validus also showed relatively high nutrient removal efficiency. ... The high nutrient availability and optimum N/P ratio were required for stimulating plant growth, resulting in allocation of more resources to above-ground tissues compared to below-ground parts, and enhancing nutrient removal efficiency. Nutrient removal efficiencies were significantly influenced by growth of C. indica and S. validus, nutrient loading rates and N/P ratios in the wastewater. The nutrient uptake kinetics of C. indica and S. validus were investigated to elucidate the differences in nutrient uptake between species. Wetland plant species have shown differential nutrient uptake efficiency and different preferences for inorganic N source, with C. indica preferring NO3-N and S. validus preferring NH4-N. C. indica had greater capacity than S. validus to take up PO4-P when the concentration of PO4-P in the solution was relatively low, whereas S. validus was more capable than C. indica to take up NO3-N when the concentration of NO3-N in the solution was relatively low. The PO4-P uptake capacity was higher in younger than older plants. Overall, the study has suggested that different plant species have differential capacity to take up nutrients. In addition to nutrient uptake, plants have significant other roles in terms of nutrient removal from the wastewater (such as leaking oxygen into the rhizosphere in which oxidation of substances like ammonia can occur). The properly high nutrient availability and optimum N/P ratio are required to stimulate the plant growth, resulting in enhancing the treatment performance in the wetlands. These findings have important implications for improving our ability to engineer ecological solutions to the problems associated with nutrient-rich wastewater.

Poultry production throughout Southern Kentucky is becoming a major agricultural enterprise. Rapid spread of the industry has led to many agricultural advances as well as concerns. One primary concerns is the possible nutrient build-up in pasture and cropland as a result of broiler litter application. Studies were conducted at Western Kentucky University using sorghum sudangrass (Sorghum bicolor (L.) Moench) as a forage to possibly remove excess nutrients. This project led to a consideration of using a cover crop to further remove nutrients from broiler litter amended soils. This study's objective was to assess total nutrient removal by sorghum sudangrass followed by a rye (Secale cereale L.) cover crop compared to single crop of sorghum sudangrass as a tool for preventing excess soil nutrient accumulation. A randomized complete block experiment was established in 2005 with four replications and four treatments was conducted: litter applied at recommended nitrogen [Litter-N] rate; litter applied at the recommended P rate with commercial nitrogen [Litter-P+N]; litter applied at the recommended P rate [Litter-Pj; and soil amended with inorganic fertilizer [INORG], Sorghum sudangrass was seeded in the spring and rye planted after the last harvest of the season. Forage acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), P, Cu, Fe, and Zn were determined, as well as soil nutrient levels. After analyzing the data from one year, 2005, it was determined that, although differences were noted, the rye cover crop did not mitigate available soil P, Cu, and Zn.