Articoli di riviste: "Aerated package treatment systems"

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García, J., R. Mujeriego, A. Bourrouet, G. Peñuelas e A. Freixes. "Wastewater treatment by pond systems: experiences in Catalonia, Spain". Water Science and Technology 42, n. 10-11 (1 novembre 2000): 35–42. http://dx.doi.org/10.2166/wst.2000.0603.

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An evaluation of the 24 existing pond systems for treatment of urban wastewater in Catalonia (north-eastern Spain) was conducted in 1997-1998. The evaluation covered 13 aerated ponds, 7 waste stabilization ponds (WSP), and 4 maturation ponds added to conventional biological wastewater treatment plants (WWTP). The technical characteristics of the pond systems were obtained through a survey completed during several visits to the plants. Performance data was supplied by the Catalonia Wastewater Agency and the monthly monitoring campaigns conducted during 12 months in five WWTP. The average ratio of water surface to population equivalent (p-e) is 1.3 m2/p-e for aerated ponds, 9.6 m2/p-e for WSP and 1.7 m2/p-e for maturation ponds added to conventional WWTP. Average electrical energy consumption is 0.5 kW.h/m3 for aerated ponds and 0.04 kW.h/m3 for WSP (when wastewater has to be pumped from the sewer). Most of the WSP show an inadequate level O & M, because the very limited operator attendance (0.6 h/dayon average) as compared to aerated ponds (3.2 h/day on average). Effluent quality of aerated ponds (31 mg SS/l and 22 mg BOD5/l, on average) is usually better that of WSP (100 mg SS/l and 67 mg BOD5/l, on average). Most of the WSP are overloaded, with only two of the pond systems receiving less than 50 kg BOD5/ha. Facultative WSP show a better performance than anaerobic WSP; anaerobic WSP have very high overloading conditions (with more than 250 kg BOD5/ha.d). Average effluent quality of all the pond systems studied comply with European Union standards.

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Hulsman, A., e C. D. Swartz. "Development of an Improved Compact Package Plant for Small Community Wastewater Treatment". Water Science and Technology 28, n. 10 (1 novembre 1993): 283–88. http://dx.doi.org/10.2166/wst.1993.0245.

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The challenges facing the design and operation of small community wastewater treatment plants are discussed. The package plant concept is considered and the consequent development of a compact intermittently aerated activated sludge package plant is outlined. A four month trial period, comprising the first part of the evaluation, is described. Results from this trial show that the plant can serve communities of up to 300 p.e. and that treated effluent quality conforms to the General South African Standards. The compact design and unique operating regime offer reduced capital and running costs respectively.

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Nivala, Jaime, Clodagh Murphy e Andrew Freeman. "Recent Advances in the Application, Design, and Operations & Maintenance of Aerated Treatment Wetlands". Water 12, n. 4 (21 aprile 2020): 1188. http://dx.doi.org/10.3390/w12041188.

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This paper outlines recent advances in the design, application, and operations and maintenance (O&M) of aerated treatment wetland systems as well as current research trends. We provide the first-ever comprehensive estimate of the number and geographical distribution of aerated treatment wetlands worldwide and review new developments in aerated wetland design and application. This paper also presents and discusses first-hand experiences and challenges with the O&M of full-scale aerated treatment wetland systems, which is an important aspect that is currently not well reported in the literature. Knowledge gaps and suggestions for future research on aerated treatment wetlands are provided.

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Hanna, K. "Onsite aerobic package treatment systems". Water Research 29, n. 11 (novembre 1995): 2530–40. http://dx.doi.org/10.1016/0043-1354(95)00094-2.

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Hamoda, Mohamed F., e Hamed A. Al-Sharekh. "Sugar wastewater treatment with aerated fixed-film biological systems". Water Science and Technology 40, n. 1 (1 luglio 1999): 313–21. http://dx.doi.org/10.2166/wst.1999.0062.

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Wastewater effluents from the sugar industry contain high concentrations of organic materials which are sometimes discharged into the municipal wastewater collection system and processed in wastewater treatment plants along with domestic wastewater. This study examined the performance of a four-compartment, fixed-film system in which the biofilm is attached to submerged ceramic tiles under diffused aeration, known as the aerated submerged fixed-film (ASFF) process. Field experiments were conducted using four ASFF units each of about 100 1 capacity operated at different hydraulic loading rates to provide hydraulic residence time (HRT) of 2, 4, 6 and 8 hours. Process performance was evaluated under both normal operation with domestic wastewater and under pulse and prolonged organic shock loads with sugar wastewater. The influent and effluent of the process was analyzed for solids, BOD, COD, and nitrogen forms to determine both carbonaceous and nitrogenous substrate removal. The ASFF process was found to be able to handle continuous severe organic loads increasing from about 5 to 120 g BOD/m2.d with slight decrease in organic removal efficiency from 97.9% to 88.5% for BOD and from 73.6 to 67.8% for COD. Nitrification was similarly decreased but at higher rates. The system was also able to cope with pulse injection of sugar wastewater and recovery to normal steady-state COD values was achieved in 10 hours for the 200 g COD/l spikes. An increase in the organic loading rate was accompanied by an increase in biofilm specific oxygen uptake rate until reaching a maximum which determines the optimum loading rate for process operation. Substrate removal rates were evaluated for process design.

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Andreadakis, A. D., G. Kondili, D. Mamais e A. Noussi. "Treatment of septage using single and two stage activated sludge batch reactors systems". Water Science and Technology 32, n. 9-10 (1 novembre 1995): 95–104. http://dx.doi.org/10.2166/wst.1995.0674.

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The cyclic or sequencing batch activated sludge process was applied for the treatment of septage originating from cesspools serving non-sewered areas. Single and two stage systems were investigated in bench scale units. The single stage aerated system was capable in removing practically all the biodegradable COD and producing a well stabilised excess sludge with excellent settling and thickening characteristics. With respect to nitrogen the average removal rate was to the order of 70%, but the performance was unstable due to periodic strong inhibition of the nitrification process. Subsequent treatment in a second stage aerated unit improved nitrification but did not result in higher nitrogen removal rates due to the increased concentrations of oxidised nitrogen. An anoxic second stage post denitrification unit resulted in an overall nitrogen removal of 88%, through a substantial reduction of nitrates. Further improvement of the system, with nitrogen removal of about 95% and average effluent nitrogen concentrations lower than 10 mg.1−1, can be achieved by adoption of a two stage system consisting of a first aerated stage unit, followed by a second stage unit with alternating aerated and anoxic cycles and addition of external carbon during the anoxic cycle.

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Freeman, A. I., S. Widdowson, C. Murphy e D. J. Cooper. "Economic assessment of aerated constructed treatment wetlands using whole life costing". Water Science and Technology 80, n. 1 (1 luglio 2019): 75–85. http://dx.doi.org/10.2166/wst.2019.246.

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Abstract There is increasing pressure on water treatment practitioners to demonstrate and deliver best value and sustainability for the end user. The aim of this paper is to evaluate the sustainability and economics, using whole life costing, of wastewater treatment technologies used in small community wastewater treatment works (WwTW) of <2,000 population equivalent (PE). Three comparable wastewater treatment technologies – a saturated vertical flow (SVF) aerated wetland, a submerged aerated filter (SAF) and a rotating biological contactor (RBC) – were compared using whole life cost (WLC) assessment. The study demonstrates that the CAPEX of a technology or asset is only a small proportion of the WLC throughout its operational life. For example, the CAPEX of the SVF aerated wetland scenario presented here is up to 74% (mean = 66 ± 6%) less than the cumulative WLC throughout a 40-year operational time scale, which demonstrates that when comparing technology economics, the most cost-effective solution is one that considers both CAPEX and OPEX. The WLC assessment results indicate that over 40 years, the SVF aerated wetland and RBC technologies have comparable net present value (NPV) WLCs which are significantly below those identified for submerged aerated filter systems (SAF) for treatment of wastewater from communities of <1,000PE. For systems designed to treat wastewater from communities of >1,000PE, the SVF aerated wetland was more economical over 40 years, followed by the RBC and then the SAF. The aerated wetland technology can therefore potentially deliver long-term cost benefits and reduced payback periods compared to alternative treatment technologies for treating wastewater from small communities.

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Krauth, Karlheinz. "Application of Preliminary Denitrification to Aerated Sludge Treatment". Water Science and Technology 21, n. 6-7 (1 giugno 1989): 699–707. http://dx.doi.org/10.2166/wst.1989.0272.

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Upstream denitrification is a technologically operable process in all treatment systems aimed at maximum nitrification (limited by the supply of organic carbon compounds). This paper considers the design and engineering of the facility, plant arrangements and the results obtained.

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Gichana, Zipporah, David Liti, Silke-Silvia Drexler, Werner Zollitsch, Paul Meulenbroek, Joseph Wakibia, Erick Ogello, Peter Akoll e Herwig Waidbacher. "Effects of aerated and non-aerated biofilters on effluent water treatment from a small-scale recirculating aquaculture system for Nile tilapia (Oreochromis niloticus L.)". Die Bodenkultur: Journal of Land Management, Food and Environment 70, n. 4 (21 aprile 2020): 209–19. http://dx.doi.org/10.2478/boku-2019-0019.

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Summary Most recirculation aquaculture systems (RAS) use aerated biofilters to maintain suitable water quality for fish production. However, application of non-aerated biofilters may provide opportunities to lower aeration costs, water usage and concentration of all nitrogenous wastes in the effluent water. Our study aimed at comparing the biofiltration performance characteristics of two biofilters: a conventional aerated biofilter and a non-aerated biofilter receiving the same effluent water from a small-scale RAS. The two biofilters were evaluated in triplicate and tested concurrently for seven months. Water quality parameters were monitored at the biofilter inlets and outlets and in the fish tanks. At the beginning of the experiment, the concentration of ammonia at the two biofilter outlets were not significantly different. However, the concentrations decreased with time reaching mean values of 1.33 ± 0.02 mg L−1 and 1.23 ± 0.21 mg L−1 N-NH4 in the aerated and non-aerated biofilters, respectively. Whereas phosphorus and nitrate levels were significantly high in the aerated biofilter. There was no significant difference in the growth of fish between the aerated and non-aerated biofilters. The results suggest that non-aerated biofilters can be as effective as aerated biofilters in maintaining suitable water quality for O. niloticus production.

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DeMers, Larry D., Boyd D. Hanzon, Frank L. Glick e Robert M. Schultz. "Design Considerations for Package Water Treatment Systems". Journal - American Water Works Association 80, n. 8 (agosto 1988): 58–61. http://dx.doi.org/10.1002/j.1551-8833.1988.tb03090.x.

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Donoso, Natalia, Dion van Oirschot, Jayanta Kumar Biswas, Evi Michels e Erik Meers. "Impact of Aeration on the Removal of Organic Matter and Nitrogen Compounds in Constructed Wetlands Treating the Liquid Fraction of Piggery Manure". Applied Sciences 9, n. 20 (14 ottobre 2019): 4310. http://dx.doi.org/10.3390/app9204310.

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The increasing demand for sustainable, robust and cost-efficient wastewater treatment techniques strengthen the implementation of constructed wetlands (CWs) in the agricultural sector. In countries like Belgium (Flanders), the compliance of strict water quality standards and surface area requirements have hindered considerably their application. New wetland designs such as aerated CWs, could help to overcome these challenges. This study evaluated the capacity of artificially aerated mesocosm systems to decrease chemical oxygen demand (COD) concentrations below the 125 mgO2/L limit imposed on installations treating animal manure. The treatment of this high-strength wastewater has been slightly studied via aerated CWs. A three-stage experiment investigated the effect of constant, intermittent and non-aeration regimes on: ammonium volatilisation, the evolution of organic and nitrogen compounds concentrations, and denitrification. The results were assessed through a mixed modelling procedure using SAS 9.4 software. A COD removal between 65% and 58% in constantly and intermittent aerated systems, versus 27% COD removal in the non-aerated system indicated the effectiveness of aeration. However, a dissimilarity was encountered in the removal of nitrogen compounds, resulting in an 82% decrease of nitrate concentrations in the non-aerated system, versus 0.5% and 11% in the aerated ones. Based on the results, this experimental set-up adjusted to field operational conditions can prove that aerated CWs can treat the liquid fraction of piggery manure.

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Roeder, Eberhard, e William G. Brookman. "Assessment of Nitrogen Reduction Limitations in Aerated Onsite Sewage Treatment Systems". Proceedings of the Water Environment Federation 2010, n. 9 (1 gennaio 2010): 6965–72. http://dx.doi.org/10.2175/193864710798206883.

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Ozturk, I., V. Eroglu e I. Toröz. "Pilot and Full-Scale Treatment Experiences on Paper Mill Effluents". Water Science and Technology 22, n. 9 (1 settembre 1990): 255–63. http://dx.doi.org/10.2166/wst.1990.0090.

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In this paper, biological treatability study results of a pilot-scale aerated lagoon treating white-waters from a mechanical groundwood-based pulp and paper mill, and long-term operating experiences on two full-scale aerated lagoon systems are presented. Biological treatability study was conducted in a 200 1 semi-pilot aerated lagoon. The results have shown that five-day Biochemical Oxygen Demand (BOD5) values are less than 50 mg/l for a hydraulic retention time of 5 days. BOD removal rate constant (K) was found as 1.01 per day for 20°C. Bioassay tests were also conducted to evaluate the toxic impacts of white-waters on receiving waters and 96 hours median tolerance level TL(96), was found as 84% for species Lapistes reticularis. Long-term operating results from two full-scale wastewater treatment plants for paper mill effluents are also presented.

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Hellström, D., e L. Jonsson. "Evaluation of small wastewater treatment systems". Water Science and Technology 48, n. 11-12 (1 dicembre 2004): 61–68. http://dx.doi.org/10.2166/wst.2004.0804.

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Different technologies for the treatment of wastewater from single houses have been evaluated by performing measurements at 14 treatment plants installed at different one-family houses located 35 km south-west of Stockholm. The technologies tested were selected in order to deliver high removal efficiencies with respect to organic matter, nitrogen and phosphorus. They also had to fulfil requirements concerning robustness, nutrient recycling, use of natural resources, economy, user-friendliness and hygiene. The systems can be divided into package plants, urine separating systems, blackwater separating systems and chemical precipitation as a supplement to sand filter beds. All of the systems were able to remove more than 90% of phosphorus and more than 90% of organic matter. Concerning package plants, it is necessary to have reliable dosing equipment and frequent checks to achieve long-term phosphorus removal. The source separation systems require well-informed and motivated users to achieve desirable removal efficiency. Sorting systems seem to be superior with respect to nitrogen removal, even though some of the package plants gave nitrogen removal above 50% during long periods of operation.

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Freeman, Andrew I., Ben W. J. Surridge, Mike Matthews, Mark Stewart e Philip M. Haygarth. "New approaches to enhance pollutant removal in artificially aerated wastewater treatment systems". Science of The Total Environment 627 (giugno 2018): 1182–94. http://dx.doi.org/10.1016/j.scitotenv.2018.01.261.

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Daude, D., e T. Stephenson. "Cost-effective treatment solutions for rural areas: design and operation of a new package treatment plant for single households". Water Science and Technology 48, n. 11-12 (1 dicembre 2004): 107–14. http://dx.doi.org/10.2166/wst.2004.0816.

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The design approach and operation of a newly developed package plant treating domestic sewage from single households were evaluated. Combining submerged aerated filter (SAF) technology with jet aeration and incorporating both into a compact and shallow tank resulted in a cost-effective treatment solution. A trial unit was permanently installed at a rural site, serving a single household. Jet aeration proved to be the best aeration method for the shallow bioreactor design. Further trials revealed a 50% reduction in suspended solids (SS) through the use of a static effluent filter and found that annual plant maintenance was vital to sustain stable operating conditions. Despite high variations in influent conditions, the trial unit produced good effluent quality during steady-state operation. Average effluent BOD5, COD and SS values were 19.6 mg l-1, 98 mg l-1 and 32 mg l-1 achieving overall removal efficiencies of 94.2%, 85.9% and 87.6% respectively. However, effluent ammonia nitrogen (NH4-N) levels were found to be inconsistent varying from 9 mg l-1 to over 60 mg l-1.

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Sun, Yafei, Junling Pang, Shiyao Wang, Tingting Tao, Xun Fu, Ying Zhang, Bo Sun e Jing Pan. "Confirmation the optimal aeration parameters for nitrogen removal and nitrous oxide emission in wastewater ecological soil infiltration systems with brown earth". Water Science and Technology 80, n. 1 (1 luglio 2019): 144–52. http://dx.doi.org/10.2166/wst.2019.260.

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Abstract Nitrogen removal is an obstacle for the wide application of wastewater ecological soil infiltration (WESI) system in domestic wastewater treatment. In this study, matrix dissolved oxygen (DO), nitrogen removal and nitrous oxide (N2O) emission in aerated pilot WESI systems were investigated under different aeration times (1, 2, 3, 4 and 6 h/d) and aeration rates (1, 2, 3 and 4 L/min). The results showed that aerobic conditions in upper matrix and anoxic or anaerobic conditions in the subsequent matrix were developed in an aerated/non-aerated cycle at the optimal aeration condition of aeration time of 4 h/d and aeration rate of 3 L/min. Simultaneously, high removal efficiency of chemical oxygen demand (COD) (97.9%), NH4+-N (98.2%), total nitrogen (TN) (90.7%) and low N2O emission rate (13.2 mg/(m2 d)) were obtained. The results would provide optimal aeration parameters for application of intermittent aerated WESI systems.

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Dalentoft, Eva, e Peter Thulin. "The use of aerobic selectors in activated sludge systems for treatment of wastewater from the pulp and paper industry". Water Science and Technology 35, n. 2-3 (1 febbraio 1997): 181–88. http://dx.doi.org/10.2166/wst.1997.0513.

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Lab-scale have been made with an aerobic selector followed by an aerated reactor. Sulphate mill effluent and waste paper mill effluent were used during the tests. It was verified that the treatment system could produce a sludge with an SVI below 140 ml/g and a high COD-reduction. It was also found that a high fraction of the COD was reduced as uptake and storage in the selector. The COD was thereafter oxidized in the aerated reactor. Full scale plants have been studied where aerobic selectors are used. The plants produce a sludge with a stable SVI below 150 ml/g. This enables a stable function regarding COD-reduction at varying loading conditions and at frequent product quality changes.

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Björlenius, B., e L. G. Reinius. "Use of on-line data to evaluate the activity in the biological stage at a wastewater treatment plant". Water Science and Technology 37, n. 9 (1 maggio 1998): 33–40. http://dx.doi.org/10.2166/wst.1998.0337.

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Today many WWTPs are equipped with different on-line instruments for automatic and manual control of the process. The use of computerised systems for data acquisition gives us new possibilities to evaluate collected data. This study shows the possibilities and potentials in using standard equipment, simple calculations and the biological stage as a measuring cell for activity determinations. Evaluation of data from Henriksdal and Bromma WWTP give some examples from the biological stage where activity can be calculated on-line. The calculation of Oxygen Uptake Rates, OUR, can be used in several ways: a) Estimation of the overall activity in the aerated part of biological stage. b) Calculations of the load of oxygen consuming substanses on the aerated basin. c) Calculation of nitrification rate. d) Estimation of necessary aerated volume. e) Rapid detection of inhibition of the nitrification (and other oxygen consuming reactions). One advantage with these calculations is the fast response to changes.

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Jupsin, H., e J. L. Vasel. "Modelisation of the contribution of sediments in the treatment process case of aerated lagoons". Water Science and Technology 55, n. 11 (1 giugno 2007): 21–27. http://dx.doi.org/10.2166/wst.2007.341.

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In aerated lagoons and even more in stabilization ponds the specific power (W/m3) is not high enough to maintain all the suspended solids in suspension. Some part of the suspended solids (including biomass) settles directly into the reactor and not in the final settling pond. The gradual accumulation of those sediments on the pond bottom affects performance by reducing the pond volume and shortening the Hydraulic Residence Time. However, the role played by these deposits is not restricted to such a physical effect. Far from being inert sediments they are also an important oxygen sink that must be taken into account when designing aerator power and oxygen supply, for example. On the other hand, under aerobic conditions, the upper layer of sediments may contribute to the treatment as a biofilm compartment in the reactor. In aerated lagoon systems another process contributes to the interaction of deposits and the liquid phase: the operating (often sequencing) of aerators may induce a drastic resuspension of deposits. In a 3,000 m3 aerated lagoon we evaluated that 3 tons of deposits were resuspended when aerators were started. Due to those processes we consider that a mathematical model of an aerated lagoon or of a stabilization pond has to take into account the contribution (positive and negative aspects) of deposits in the process. In this paper we propose a model for sediments including production but also biological processes. Simulations of the aerated lagoon with or without the “sediment compartment” demonstrate the effect and the importance of this compartment on the process. Of course a similar approach could be used for facultative or even maturation ponds. The next step would be to include anaerobic activities in the bottom layer.

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Pang, Junling, Mo Yang, Deli Tong, Xu Fu, Linli Huang, Bo Sun e Jing Pan. "Does influent C/N ratio affect pollutant removal and greenhouse gas emission in wastewater ecological soil infiltration systems with/without intermittent aeration?" Water Science and Technology 81, n. 4 (15 febbraio 2020): 668–78. http://dx.doi.org/10.2166/wst.2020.141.

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Abstract Wastewater ecological soil infiltration system (WESIS) is a land treatment technology for decentralized wastewater treatment that has been applied all over the world. In this study, the pollutant removal, emission of greenhouse gases (GHGs) and functional gene abundances with different influent C/N ratios were evaluated in WESISs with/without intermittent aeration. Intermittent aeration and influent C/N ratio affect pollutant removal and GHG emission. Increased influent C/N ratio led to high total nitrogen (TN) removal, low CH4 and N2O emission in the aerated WESIS, which was different from the non-aerated WESIS. High average removal efficiencies of chemical oxygen demand (COD) (94.8%), NH4+-N (95.1%), TN (91.2%), total phosphorus (TP) (91.1%) and low emission rates for CH4 (27.2 mg/(m2 d)) and N2O (10.5 mg/(m2 d)) were achieved with an influent C/N ratio of 12:1 in the aerated WESIS. Intermittent aeration enhanced the abundances of bacterial 16S rRNA, amoA, nxrA, narG, napA, nirK, nirS, qnorB, nosZ genes and decreased the abundances of the mcrA gene, which are involved in pollutant removal and GHG emission. Intermittent aeration would be an effective alternative to achieving high pollutant removal and low CH4 and N2O emission in high influent C/N ratio wastewater treatment.

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Akca, L., e A. Samsunlu. "Performance evaluation of small treatment systems in Turkey". Water Science and Technology 41, n. 1 (1 gennaio 2000): 49–52. http://dx.doi.org/10.2166/wst.2000.0008.

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In accordance with the development of tourism, sea pollution has become the major problem of the coastal zones. In order to realize sustainable touristic activities in Turkey, it is very important to treat wastewater and preserve the environmental quality. It is roughly estimated that there are around 2000 small treatment plants in Turkey. However, it is necessary to construct 10,000 more wastewater treatment plants to solve the wastewater problems in small settlements. In this study, performances of small treatment systems were investigated. Two types of the treatment plants were of concern. The first one is a continuous system based on fixed bed activated sludge process, whereas the second system is based on batch activated sludge process. 96 treatment plants have been investigated in this study. The wastewater characteristic is determined as strong domestic wastewater. It has been observed that the effluent quality of the batch activated sludge and aerated biofilter systems meet the discharge requirements of Water Pollution Control Regulation in Turkey. Furthermore, they would be easily adapted to meet the stringent standards that are proposed for sensitive zones.

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Arias, C. A., D. V. Oirschot, R. Kilian, A. Pascual, P. Carvalho, T. Lv, Y. Zhang, H. Brix e J. A. Alvarez. "Design and performance evaluation of a highly loaded aerated treatment wetland managing effluents from a food processing industry in Denmark". Water Practice and Technology 10, n. 4 (1 dicembre 2015): 644–51. http://dx.doi.org/10.2166/wpt.2015.074.

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Treating highly loaded industrial effluents are challenging when treatment wetlands (TWs) are the choice selected for treatment. If TWs are selected as the solution, passive systems demand relatively large areas and may generate operational limitations and are not flexible in case of new treatment demands since no process adjustments can be made once the system is built. New types of intensified TW, such as aerated systems, have opened new possibilities in the field of the Wetland Technology and have shown capacity to treat several types of wastewater (WW). Aerated wetlands have been built across the USA and several European countries, but not a single system has been built in Denmark as to date. Thanks to an EU funded project and the cooperation of several partners under a consortium with the acronym HIGHWET, a new system is being built at the premises of a food processing factory in the vicinity of Faarup Denmark. The system will treat the WW generated at the plant and consists of a pretreatment system in the form of an anaerobic reactor, followed by two 1 m deep vertical flow beds, one of them aerated while the other bed is not aerated. Following these beds, the plant has two horizontal sub-surface flow beds fitted with aeration. For improving the P removal, media with high P binding capacity is are being used as filling material. In additiuon and for research purposes, the influent pump well plant is fitted with a dosing system in order to obtain pollutant loads at will so performance limits and kinetic constants can be established from the performance of the plant.

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Albertson, O. E., e H. D. Stensel. "Aerated Anoxic Biological NdeN Process". Water Science and Technology 29, n. 7 (1 aprile 1994): 167–76. http://dx.doi.org/10.2166/wst.1994.0334.

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The conventional practice for an anoxic denitrification basin has been to minimize oxygen input on the basis that it is detrimental to the process. For existing secondary treatment systems, allotting 25-35% of the aeration volume for an unaerated anoxic zone will significantly reduce plant capacity. Further, one group has held that bulking control is best achieved by eliminating all forms of oxygen from the initial contact or biological selector zones. The Phoenix 91st Avenue WWTP was designed with nitrate recycle to aerated selector zones and the anoxic zones were provided with a dense array of fine bubble diffusers. The prototype NdeN process was able to maintain the 1.31 m3/s secondary capacity with aerated anoxic zone receiving 20-25% of the total airflow. Net sludge yields were 30-50% higher than anticipated due to primary clarifier solids losses at higher flows which reduced SRTT to ≤ 5 days. At 5.0-5.5 day SRTT, effluent averaged 8.3 mg/L TN, 1.75 mg/L NH4N and 5.7 mg/L NO3N. Nitrobacter N oxidation rates were unexplainably lower than the Nitrosomonas N oxidation rates causing effluent NO2N.

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Park, H. D., J. M. Regan e D. R. Noguera. "Molecular analysis of ammonia-oxidizing bacterial populations in aerated-anoxic Orbal processes". Water Science and Technology 46, n. 1-2 (1 luglio 2002): 273–80. http://dx.doi.org/10.2166/wst.2002.0489.

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Aerated-anoxic processes operate under the principle that small additions of oxygen to an anoxic reactor induce simultaneous nitrification and denitrification. In these systems, ammonia oxidation in the anoxic zone can easily account for 30–50% of the total nitrification in the reactor, even though the dissolved oxygen concentration is usually below detection limit. To investigate whether the nitrification efficiency in aerated-anoxic processes was due to the presence of specialized ammonia-oxidizing bacteria (AOB), an analysis of the AOB population in an aerated-anoxic Orbal process and a conventional nitrogen removal process was carried out using phylogenetic analyses based on the ammonia monooxygenase A (amoA) gene. Terminal restriction fragment length polymorphism (TRFLP) analyses revealed that Nitrosospira-like organisms were one of the major contributors to ammonia oxidation in a full-scale aerated-anoxic Orbal reactor. However, the relative populations of Nitrosospira-like and Nitrosomonas-like AOB were not constant and appeared to have seasonal variability. Cloning and sequence comparison of amoA gene fragments demonstrated that most of the AOB in the aerated-anoxic Orbal process belonged to the Nitrosospira sp. and Nitrosomonas oligotropha lineages. The abundance of Nitrosospira-like organisms in aerated-anoxic reactors is significant, since this group of AOB has not been usually associated with nitrification in wastewater treatment plants.

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Schlegel, S., e H. Koeser. "Wastewater treatment with submerged fixed bed biofilm reactor systems – design rules, operating experiences and ongoing developments". Water Science and Technology 55, n. 8-9 (1 aprile 2007): 83–89. http://dx.doi.org/10.2166/wst.2007.245.

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Abstract (sommario):

Wastewater treatment systems using bio-films that grow attached to a support media are an alternative to the widely used suspended growth activated sludge process. Different fixed growth biofilm reactors are commercially used for the treatment of municipal as well as industrial wastewater. In this paper a fairly new fixed growth biofilm system, the submerged fixed bed biofilm reactor (SFBBR), is discussed. SFBBRs are based on aerated submerged fixed open structured plastic media for the support of the biofilm. They are generally operated without sludge recirculation in order to avoid clogging of the support media and problems with the control of the biofilm. Reactor and process design considerations for these reactors are reviewed. Measures to ensure the development and maintenance of an active biofilm are examined. SFBBRs have been applied successfully to small wastewater treatment plants where complete nitrification but no high degree of denitrification is necessary. For the pre-treatment of industrial wastewater the use of SFBBRs is advantageous, especially in cases of wastewater with high organic loading or high content of compounds with low biodegradability. Performance data from exemplary commercial plants are given. Ongoing research and development efforts aim at achieving a high simultaneous total nitrogen (TN) removal of aerated SFBBRs and at improving the efficiency of TN removal in anoxic SFBBRs.

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27

Pascual, A., D. de la Varga, C. A. Arias, D. Van Oirschot, R. Kilian, J. A. Álvarez e M. Soto. "Hydrolytic anaerobic reactor and aerated constructed wetland systems for municipal wastewater treatment – HIGHWET project". Environmental Technology 38, n. 2 (31 maggio 2016): 209–19. http://dx.doi.org/10.1080/09593330.2016.1188995.

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28

Stumpf, D., H. Zhu, B. Heinzmann e M. Kraume. "Phosphorus recovery in aerated systems by MAP precipitation: optimizing operational conditions". Water Science and Technology 58, n. 10 (1 novembre 2008): 1977–83. http://dx.doi.org/10.2166/wst.2008.549.

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Abstract (sommario):

An attractive way of recovering essential phosphorus from digested sludge of a WWTP is the precipitation in the sludge directly, as part of the continuous treatment process. For optimizing the precipitation, 1 litre-batch tests were performed in a model system to examine the MAP-crystallization kinetics. Different parameters such as e.g. the aeration flow rate were investigated. The aim was to find an optimized setting for a pilot reactor for the continuous production of MAP. This reactor performed as an airlift reactor for an improved mixing and stripping the dissolved CO2 and separating the MAP-crystals. The optimal condition for the airlift pilot reactor is given when the air flow rate for mixing the system and for stripping CO2 for a maximum MAP precipitation is aligned with the particle size distribution.

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29

Siegrist, H., e W. Gujer. "Nitrogen removal in activated sludge systems including denitrification in secondary clarifiers". Water Science and Technology 30, n. 6 (1 settembre 1994): 101–11. http://dx.doi.org/10.2166/wst.1994.0257.

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Abstract (sommario):

Denitrification in the secondary clarifier can contribute substantially to the nitrogen removal of activated sludge systems. This is illustrated on two treatment plants with different secondary clarifier systems. A model to estimate denitrification capacity and to design activated sludge systems for nitrogen removal is developed and verified with data from two treatment plants. The model includes denitrification in the secondary clarifier, wastewater composition (soluble readily biodegradable COD, particulate degradable COD), oxygen input into the anoxic volume, temperature, and solids retention time (SRT). The influence of aerated grit chambers and primary sedimentation on denitrification is discussed.

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30

Ozimek, Teresa, Wojciech Dąbrowski e Maria Florkiewicz. "Duckweed does not improve the efficiency of municipal wastewater treatment in lemna system plants / Rzęsa nie poprawia efektywności oczyszczania ścieków komunalnych w oczyszczalniach typu Lemna System". Archives of Environmental Protection 41, n. 3 (1 settembre 2015): 47–52. http://dx.doi.org/10.1515/aep-2015-0029.

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Abstract This study investigated the operation of three full-scale Lemna System surface fl ow municipal wastewater treatment plants, built according to the Lemna Corporation design. These plants consist of two ponds, the first aerated and the second for duckweed, with a barrier grid in the latter to ensure uniform plant distribution across its area. According to designers duckweed improves the efficiency of wastewater treatment. The three treatment plants are situated in central Poland and they differ in the occurrence of duckweed, two of them, located in Raków and Bąkowiec, operate without duckweed. and the third in Falęcin Stary, Lemna minor covers ca. 90% of second pond surface. The efficiency of Lemna System wastewater treatment was found not to differ between the plants with and without duckweed. The aerated pond played the main role in reduction of pollutants in the investigated Lemna Systems

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31

Banerji, Shankha K., e Kye-Min Cho. "Evaluation of a Small-Scale Biofilm Process for Wastewater Treatment". Water Quality Research Journal 26, n. 1 (1 febbraio 1991): 87–100. http://dx.doi.org/10.2166/wqrj.1991.006.

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Abstract (sommario):

Abstract An innovative aerated biofilm process (ABP) was evaluated under laboratory conditions to treat synthetic wastewater. The particular system performed well (>90% BOD removal) at fairly high BOD loading conditions (16.7 g BOD m−2d−1). The process did not require a separate secondary settling chamber to produce an effluent low in suspended solids (<10 mgL−1). The amount of sludge produced was lower than other comparable systems — 0.3g total solids were produced per g of BOD removed at an organic removal rate of 8 g BOD m−2d−1. This process could be adopted for treating wastewater in small systems.

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32

Rantala, P., e P. Väänänen. "Cost Comparison of Aerobic and Anaerobic Wastewater Treatment Systems". Water Science and Technology 17, n. 1 (1 gennaio 1985): 255. http://dx.doi.org/10.2166/wst.1985.0020.

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Abstract (sommario):

The costs of different types of aerobic, anaerobic and combined wastewater treatment systems are compared in this study. The assumed BOD or COD-loads from typical forest industry processes form the basis of comparison. General cost curves for various waste treatment processes and some case examples are also presented. In the calculations it is assumed that the wastewater is treated to the same effluent quality by using activated sludge, modified activated sludge and combination of anaerobic-aerobic treatment process. In anaerobic-aerobic systems different types of combinations are analyzed. Investment, running and annual costs have been evaluated for each system. The study shows that selection of the method or combination of methods must always be made case by case. It has been found out that in some cases the anaerobic-aerobic process combination is economically competitive. Competitiveness will increase if biogas can be utilized and a moderate price could be calculated for it. In some cases activated sludge, and especially aerated lagoon processes, has a disadvantage of requiring larger treatment spaces. Poor soil conditions and long distances to lead effluent may significantly increase the cost of these aerobic treatment methods.

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33

Nunes, Jackeline Valendolf, Mac Wendell Barbosa da Silva, Gustavo Henrique Couto, Eduarda Roberta Bordin, Wanessa Algarte Ramdsdorf, Izadora Cervelin Flôr, Vânia Aparecida Vicente, José Daniel de Almeida, Fernanda Celinski e Claudia Regina Xavier. "Microbiological diversity in an aerated lagoon treating kraft effluent". BioResources 16, n. 3 (1 giugno 2021): 5203–19. http://dx.doi.org/10.15376/biores.16.3.5203-5219.

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Abstract (sommario):

The microbiological diversity of cultivable bacteria was analyzed in an aerated facultative lagoon. The removal of specific compounds and measures of pollutant load was evaluated with isolated native bacteria, selected and identified in kraft cellulose effluent. The system was operated with an organic loading rate of 0.2 kgCODm-3d-1 for 60 days. Analyses of the fluorescence excitation-emission matrix, acute ecotoxicity, and microbiology were performed. Bioaugmentation tests were done to emphasize the removal of color, using promising species. The removals of biochemical oxygen demand, chemical oxygen demand, and total organic carbon in AFL were 94%, 51%, and 41%, respectively. Regarding color, removal was up to 4%, and the total phenolic compounds were not removed through biological treatment. The treatment also decreased turbidity by 94% and lignin derivatives by 12%. The bacteria identified through NCBI-BLAST and statistical similarity totaled 9 species in the cellulose effluent, three of which have the potential for color treatment: Bacillus cereus, Bacillus thuringiensis, and Paenibacillus sp. The Bacillus cereus combined with biomass removed color (69%), total phenolic compounds (37%), and compounds derived from lignin (53%). These species are promising for removing specific parameters combined with biomass from biological AFL treatment systems.

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34

Peitz, Camila, e Claudia Regina Xavier. "Evaluation of aerated lagoon modified with spongy support medium treating Kraft pulp mill effluent". Revista Facultad de Ingeniería Universidad de Antioquia, n. 92 (7 giugno 2019): 60–69. http://dx.doi.org/10.17533/udea.redin.20190725.

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Abstract (sommario):

The pulp industry generates high effluent flows, which contain high chemical oxygen demand (COD), biochemical oxygen demand (BOD5), colour and ecotoxicity. This study aimed to evaluate the treatment of Kraft pulp effluent by aerated lagoon modified with sponge support media (APG). It was assessed the arrangement of the support media in the aerated lagoons in the organic load rate (OLR) of 0.2 kgCOD m-3 d-1, and after that, with OLR variation from 0.2 to 1.2 kgCOD m-3 d-1. The parameters evaluated were BOD5, COD, colour, lignin derivatives, total phenolic compounds and acute ecotoxicity in D. magna. COD and BOD5 removals were 32% and 88%, respectively, for free and confined support media in 0.2 kgCOD m-3 d-1. There was no colour or total phenolic compounds removal under these conditions. Considering the treatment in which there was a variation of the organic load rate, 1.2 kgCOD m-3 d-1 had the best performance. In this case, 50% and 75% of COD and BOD5 were removed, respectively. Removal of colour, total phenolic compounds and lignin derivatives were around 20%, 18% and 10%, respectively. The acute ecotoxicity was reduced to toxicity factor equal to 1 in all treatments. Comparing the aerated lagoon modified systems with those without the APG, it was suggested to apply spongy support in higher organic load rate than these typically used in aerated lagoons.

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35

Struve, D. K. "Seed conditioning of red oak: a recalcitrant North American seed". Scientia Agricola 55, spe (1998): 67–73. http://dx.doi.org/10.1590/s0103-90161998000500012.

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Abstract (sommario):

A ten day aerated water soak was developed as a seed conditioning treatment for red oak (Quercus rubra L.). Conditioned seeds had higher germination completeness, uniformity and speed compared to control seeds. Seeds could be conditioned under a wide range of temperatures and durations. Conditioned seeds were maintained at 7(0)C for 30 days without loss of seed quality. During conditioning, pericarps split in response to seed hydration. Split pericarps could be used as a pre-sowing indicator for high quality seeds. Seed conditioning was ineffective on dormant seeds. Increased crop uniformity and higher stand establishment can be realized by subjecting red oak acorns to an aerated water soak treatment followed by selecting seeds with split pericarps. These results are especially important in container production systems where limited numbers of value seeds are available.

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36

d'Antonio, Giuseppe, Luigi Mendia, Francesco Pirozzi e Arturo Polese. "Rotating biological contactor-solid contact system for the treatment of wastewater from small communities". Water Science and Technology 35, n. 6 (1 marzo 1997): 109–18. http://dx.doi.org/10.2166/wst.1997.0249.

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Abstract (sommario):

In Rotating Biological Contactor (RBC) WasteWater Treatment Plants (WWTP) the fixed film unit effluent quality can be improved by means of a biological refinement system, consisting of an aerated Solid Contact (SC) unit. This process, known as an RBC/SC system, is an alternative to other tertiary treatment systems and can be used with good results in the new WWTPs of small communities and in upgrading existing RBC plants whose effluents no longer respect the established standards. The results of an experimental study on an RBC/SC dual biological system fed with clarified municipal sewage are presented and used to validate a new concept mathematical model of each system's phase behaviour. RBC removal efficiency proved to be near stable for total COD while it tended to decrease for particulate COD at higher load values. The aerated SC phase allowed the overall removal efficiency to be improved; the main advantage was observed in the suspended matter removal increase (averaging 26%), while for total and soluble COD the increases averaged 18 and 17% respectively.

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37

Chin, Kee Kean, e Say Leong Ong. "Treatment and reuse of water for prawn cultivation". Water Science and Technology 30, n. 9 (1 novembre 1994): 255–58. http://dx.doi.org/10.2166/wst.1994.0492.

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Abstract (sommario):

An experimental prawn pond of 600 sq m surface area and 2 m depth was used for the cultivation of tiger prawn. Thirty-thousand 14-day PL flies were stocked. Water treatment systems consisting of primary sedimentation, aerated biofilter and inclined plate final sedimentation were installed for treatment and recycling of the pond water. With complete recycling and reuse of the pond water and occasional replenishing with seawater to make up for losses due to evaporation, water quality was maintained at an acceptable level. Survival rate of the prawn was above 80 %. Prawn yield was estimated to be around 7.6 tonnes/hectare-cycle or 22.8 tonnes/hectare-year.

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38

M. T. M. Oliveira, Leonardo, José L. S. Duarte, Vanderson B. Bernardo, Andreza Porto Moura, Aureo Alves de S. Neto, Eduardo J. S. Fonseca e Laís F. A. M. Oliveira. "Numerical study of the filtering barriers influence to contain aerated particulate systems". International Journal of Scientific Research and Management 10, n. 12 (13 dicembre 2022): 28–45. http://dx.doi.org/10.18535/ijsrm/v10i12.m01.

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Abstract (sommario):

Since the high rate of viral proliferation caused by Covid-19, it was observed that microdroplets with a pathogenic load can remain floating when in confined environments due to their low densities. They are also subject to being transported very easily when in open environments, becoming potential agents of infection. It has motivated several researchers in the field of particulate systems to try understand how particles behave in more extreme conditions. Bearing in mind that the materials currently used have a low retention yield for liquid droplets, and that protection barriers against pathogens are present both in daily use in hospital application, from diagnosis to treatment, this work simulated computationally, in a Eulerian-Eulerian approach, fluid particle retention efficiency in filter films. The simulated results indicated the high degree of retention of the filtering medium and the dependence of its saturation on the particle diameter and flow velocity, in which the greater the initial flow velocity and larger particles, the faster the saturation and detachment of particles, reducing the filter medium containment capacity. However, the results indicated that even so, retainer materials are efficient in reducing the proliferation of pathogenic loads.

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39

Carlsson, Bengt, e Jesús Zambrano. "Fault detection and isolation of sensors in aeration control systems". Water Science and Technology 73, n. 3 (20 ottobre 2015): 648–53. http://dx.doi.org/10.2166/wst.2015.529.

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Abstract (sommario):

In this paper, we consider the problem of fault detection (FD) and isolation in the aeration system of an activated sludge process. For this study, the dissolved oxygen in each aerated zone is assumed to be controlled automatically. As the basis for an FD method we use the ratio of air flow rates into different zones. The method is evaluated in two scenarios: using the Benchmark Simulation Model no. 1 (BSM1) by Monte Carlo simulations and using data from a wastewater treatment plant. The FD method shows good results for a correct and early FD and isolation.

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40

Andersson, B. "Tentative Nitrogen Removal with Fixed Bed Processes in Malmö Sewage Treatment Plant". Water Science and Technology 22, n. 1-2 (1 gennaio 1990): 239–50. http://dx.doi.org/10.2166/wst.1990.0150.

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Abstract (sommario):

A test program for the use of fixed bed processes in systems for nitrogen removal at an advanced sewage treatment plant is described. Results from studies on nitrification in a full scale trickling filter plant with different filter depths and at different wastewater temperatures are presented. Results from full scale experiments with denitrification/nitrification in a retrofitted activated sludge plant are also presented. The effect of an aerated submerged fixed bed in the aeration basin on nitrification was investigated. Observations of the biofilm formed on the fixed bed were made in microscope.

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41

Jobbágy, A., B. Literáthy e G. Tardy. "Implementation of glycogen accumulating bacteria in treating nutrient-deficient wastewater". Water Science and Technology 46, n. 1-2 (1 luglio 2002): 185–90. http://dx.doi.org/10.2166/wst.2002.0475.

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Abstract (sommario):

Activated sludge treatment of nutrient-deficient wastes may lead to severe slime formation and consequent biomass separation difficulties. The purpose of this paper has been to show that bioreactor arrangement essentially influences the manner of biological excess carbon removal. In a comparative lab-scale experiment two differently arranged activated sludge systems were operated simultaneously: an aerated CSTR with an aerobic selector and an aerated CSTR with an anaerobic selector. The seed derived from an anaerobic/aerobic activated sludge plant of a winery. The model wastewater contained wine, sugar and acetic acid as organic carbon sources and lacked nutrients regarding both N and P, similarly to the influent of the full-scale plant. During the 52 days of the experiment the SVI values of the fully aerated system increased up to 600–800 cm3 g−1 whereas those of the anaerobic/aerobic system remained below 250 cm3 g−1. The SVI values showed a strict correlation with the amount of extracellular polysaccharides. In the anaerobic/aerobic experimental system, the high (40% of MLSS) intracellular polysaccharide content of the seed could be maintained. Besides the analytical data, also the microscopic observations of the biomass structure referred to the presence of glycogen accumulating organisms in both the lab- and full-scale anaerobic/aerobic systems.

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42

Roeder, Eberhard, e William G. Brookman. "Comparison of Multiple Grab and 24-hour Time-composite Samples from Aerated Onsite Sewage Treatment Systems". Proceedings of the Water Environment Federation 2008, n. 16 (1 gennaio 2008): 1452–60. http://dx.doi.org/10.2175/193864708788734999.

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43

Larsen, Penny, e Jim Sizemore. "FULLY INTEGRATING VENDOR PACKAGE SYSTEMS WITH PLANT-WIDE SCADA SYSTEMS AT MUNICIPAL WASTEWATER TREATMENT FACILITIES". Proceedings of the Water Environment Federation 2007, n. 12 (1 gennaio 2007): 6316–25. http://dx.doi.org/10.2175/193864707787969991.

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44

Oliveira, S. C., e M. von Sperling. "Performance evaluation of UASB reactor systems with and without post-treatment". Water Science and Technology 59, n. 7 (1 aprile 2009): 1299–306. http://dx.doi.org/10.2166/wst.2009.138.

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Abstract (sommario):

This article evaluates and compares the actual behavior of 18 UASB reactor systems operating without (10 plants) and with (8 plants) post treatment, considering their performance and their reliability in terms of compliance with specified discharge standards. The following types of post-treatment processes were analyzed: aerated filter; anaerobic filter; trickling filter; dissolved air flotation unit; facultative pond and maturation pond. The effluent quality and the removal efficiencies were compared with typical values reported in the technical literature. A methodology developed by Niku et al. (1979) was used for the determination of the coefficients of reliability, in terms of the compliance of effluent BOD and TSS with discharge standards. The results showed that, in general, the inclusion of a post-treatment step, be it either aerobic, anaerobic or physical-chemical, can provide a substantial improvement of the effluent quality from UASB reactors in terms of BOD and TSS. In terms of the systems reliability, the actual effluent concentrations from UASB reactor followed by some post-treatment processes would meet more restrictive discharge standards than those considered in this study (60 mg L−1 for both constituents—values prevailing in most states in Brazil).

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45

Ray, Rajan, Paul Henshaw e Nihar Biswas. "Effects of reduced aeration in a biological aerated filter". Canadian Journal of Civil Engineering 39, n. 4 (aprile 2012): 432–38. http://dx.doi.org/10.1139/l2012-022.

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Abstract (sommario):

Aeration is a major part of the operating cost in biological aerated filtration (BAF) systems for wastewater treatment. This study investigated the effect of reducing aeration at the City of Windsor’s Lou Romano Water Reclamation Plant to find the lowest possible airflow rate while maintaining a satisfactory ammonia and biological oxygen demand (BOD) in the BAF effluent. Profiles of temperature, dissolved oxygen, pH, BOD, ammonia and nitrate concentration were measured along the height of cell No. 7 at the plant, at different time intervals during filtration, at airflow rates varying from 1300 to 1700 m3/h per cell. This study found that the BOD and ammonium removal were satisfactory at the lowest airflow rate.

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46

Meister, Michael, e Wolfgang Rauch. "Modelling aerated flows with smoothed particle hydrodynamics". Journal of Hydroinformatics 17, n. 4 (9 marzo 2015): 493–504. http://dx.doi.org/10.2166/hydro.2015.132.

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Abstract (sommario):

Modelling aerated flows is a complex application of computational fluid dynamics (CFD) since the interfaces between air and water change rapidly. In this work, the simulation of aerated flows with the smoothed particle hydrodynamics (SPH) method is investigated with a focus towards the application in engineering practice. To prove the accuracy of the method, the processes of air entrainment and rising air bubbles are studied. Through monitoring the evolution of the bubble contours it is shown that the novel approach of adding artificial repulsion forces at the interface does not alter the dynamics but stabilizes the flow. Building on these fundamental processes we extend the discussion to practical applications with a special focus on forced aeration. Since the employment of a detailed SPH model to practical problems remains out of bounds due to the high computational demand, we propose a combined experimental and numerical study where experimental bubble characteristics are imposed on the numerical simulation. Based on the data of the conducted bubble column experiment, the computational demand is significantly decreased such that the oxygen consumption due to biokinetic processes can be modelled. The future perspective is to apply SPH to urban water systems, e.g., for simulating detailed processes in wastewater treatment and sewer hydraulics.

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47

Slade, A. H., C. M. Nicol e J. Grigsby. "Nutrients Within Integrated Bleached Kraft Mills: Sources and Behaviour in Aerated Stabilisation Basins". Water Science and Technology 40, n. 11-12 (1 dicembre 1999): 77–84. http://dx.doi.org/10.2166/wst.1999.0697.

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Abstract (sommario):

As constraints on the discharge of nitrogen and phosphorus from the pulp and paper industry become tighter, a thorough knowledge of nutrient sources, and their behaviour through treatment systems, is required. Once nutrient behaviour has been characterised, strategies to minimise discharge can be formulated. A survey of nutrient sources around a modern ECF integrated bleached kraft mill showed that point sources of nitrogen and phosphorus could be identified. Approximately 40% of the nitrogen was contained in the foul condensate stream and 40% of the phosphorus contained in the acid stage of bleaching. Three Aerated Stabilisation Basin treatment systems were studied, two of which were nutrient limited in terms of theoretical nutrient requirements. All three systems achieved approximately 90% BOD removal without nutrient supplementation. For the wastewater with a high BOD:N ratio (100:0.8), nitrogen fixation was shown to be important. Benthic recycling was a more important mechanism when the BOD:N ratio was lower (100:2.1). For a severely phosphorus limited wastewater (BOD:P 100:0.04), treated in a system with a long retention time (85 d), benthic recycling was the predominant mechanism for nutrient supply. The relative roles of nitrogen fixation and benthic feed back to the nitrogen cycle in aerated stabilisation basins are discussed.

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48

Meyer, U., e H. J. Pöpel. "Fuzzy-control for improved nitrogen removal and energy saving in WWT-plants with pre-denitrification". Water Science and Technology 47, n. 11 (1 giugno 2003): 69–76. http://dx.doi.org/10.2166/wst.2003.0588.

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Abstract (sommario):

In the last few years, numerous studies were carried out, dealing with the application of fuzzy-logic to improve the control of the activated sludge process. In this paper, fuzzy-logic based control strategies for wastewater treatment plants with pre-denitrification are presented that should lead to better effluent quality and, in parallel, to a reduction of energy consumption. Extensive experimental investigations on a large scale pilot plant as well as simulation studies (ASM1 with SIMBA®) were carried out in order to design, evaluate and compare different fuzzy-controllers with each other and with comparable conventional control systems. The fuzzy-controllers were designed as high-level controllers that determine the DO-setpoints in the aerated zones and the ratio between aerated and non-aerated zones. Conventional PI-controllers were used to maintain the DO-concentration at the set-point levels. The ammonia and nitrate concentration in the effluent and the ammonia load in the influent were considered as input variables for the different fuzzy-controllers. Compared to the operation with fixed nitrification/denitrification zones and constant DO concentrations, the required air-flow could be reduced up to 24% by using fuzzy-logic based control strategies. In comparison with a more advanced conventional control strategy (relay controller with two thresholds and the NH4-N concentration in the effluent as single control variable) a reduction of air-flow-rate up to 14% could be achieved. At the same time, NH4-N peaks in the effluent that are normally caused by peak flow conditions could be reduced significantly. The large scale experiments show that the fuzzy-controllers can be easily implemented in modern control and supervision systems and that the control characteristics can be followed and modified during operation. It therefore can be expected that the developed fuzzy-control systems will be accepted by the operating personnel in wastewater treatment plants.

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49

Godin, D., C. Bouchard e P. A. Vanrolleghem. "Net environmental benefit: introducing a new LCA approach on wastewater treatment systems". Water Science and Technology 65, n. 9 (1 maggio 2012): 1624–31. http://dx.doi.org/10.2166/wst.2012.056.

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Abstract (sommario):

Life cycle assessment (LCA) allows evaluating the potential environmental impacts of a product or a service in relation to its function and over its life cycle. In past LCAs applied to wastewater treatment plants (WWTPs), the system function definition has received little attention despite its great importance. This has led to some limitations in LCA results interpretation. A new methodology to perform LCA on WWTPs is proposed to avoid those limitations. It is based on net environmental benefit (NEB) evaluation and requires assessing the potential impact of releasing wastewater without and with treatment besides assessing the impact of the WWTP's life cycle. The NEB allows showing the environmental trade-offs between avoided impact due to wastewater treatment and induced impact by the WWTP's life cycle. NEB is compared with a standard LCA through the case study of a small municipal WWTP consisting of facultative aerated lagoons. The NEB and standard LCA show similar results for impact categories solely related to the WWTP's life cycle but differ in categories where wastewater treatment environmental benefit is accounted for as NEB considers influent wastewater quality whereas standard LCA does not.

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50

Abdullah, H., A. Abusam, A. Mydlarczyk, A. Al-Dhafeeri, F. Al-Ajeel, A. Ali, M. Al-Jomaa e R. Al-Yaseen. "Performance Evaluation of Commercial Package Systems Used in Kuwait for on-Site Treatment and Reuse of Domestic Wastewater". International Journal of Environmental Science and Development 14, n. 1 (2023): 22–29. http://dx.doi.org/10.18178/ijesd.2023.14.1.1410.

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Abstract (sommario):

Kuwait’s wastewater management scheme consists of a huge centralized sewerage system that transports all wastewater generated for treatment at central municipal plants for wastewater treatment. However, there are a few remote sites that are still not connected to the public sewerage system. In such sites, on-site systems such as conventional septic tank or package systems are commonly used. This study assessed the performance of two package systems used in Kuwait for on-site wastewater treatment and reuse. Wastewater samples were collected weekly for five months from influent and effluent streams of two package systems located at Ahmedi and Kadhmah areas of Kuwait. Comparison of the means of the laboratory results to the guidelines of Kuwait Public Authority for Environment (KEPA) indicated that the effluents of the two systems are suitable to be reused as irrigation water. However, results obtained also showed that performances of both units were highly fluctuating.

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