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1
Abbott, Katherine M., Peter A. Zaidel, Allison H. Roy, Kristopher M. Houle, and Keith H. Nislow. "Investigating impacts of small dams and dam removal on dissolved oxygen in streams." PLOS ONE 17, no. 11 (November 17, 2022): e0277647. http://dx.doi.org/10.1371/journal.pone.0277647.
Анотація:
Small surface-release dams are prevalent across North American watersheds and can alter stream flow, thermal regimes, nutrient dynamics, and sediment transport. These dams are often implicated as a cause of negative water quality impacts—including reduced dissolved oxygen (DO)—and dam removal is increasingly employed to restore natural stream processes and improve DO. Published impacts of small dams on DO vary widely across sites, and even less is known about the extent and timescale of DO recovery following removal. Therefore, we sought to quantify the effects of small dams and dam removal on DO and determine the dam, stream, and watershed characteristics driving inter-site variation in responses. We deployed continuous data loggers for 3 weeks during summer months in upstream (reference), impoundment, and downstream reaches at each of 15 dammed sites and collected equivalent data at 10 of those sites following dam removal. Prior to dam removal, most sites (60%) experienced a decrease in DO (an average of 1.15 mg/L lower) within the impoundment relative to upstream, but no consistent impacts on diel ranges or on downstream reaches. Before dam removal, 5 impacted stream reaches experienced minimum DO levels below acceptable water quality standards (<5 mg/L); after dam removal, 4 of 5 of these reaches met DO standards. Sites with wider impoundments relative to upstream widths and sites located in watersheds with more cultivated land experienced the greatest decreases in impoundment DO relative to upstream. Within one year following dam removal, impoundment DO recovered to upstream reference conditions at 80% of sites, with the magnitude of recovery strongly related to the magnitude of pre-removal impacts. These data suggest that broadly, small dams negatively affect stream DO, and the extent of effects are modulated by impoundment geometry and watershed characteristics. These results may help practitioners to prioritize restoration efforts at those sites where small dams are having outsized impacts, and therefore where the greatest water quality benefits may occur.
2
Zhang, Yiding, Li Zhang, and William J. Mitsch. "Predicting river aquatic productivity and dissolved oxygen before and after dam removal." Ecological Engineering 72 (November 2014): 125–37. http://dx.doi.org/10.1016/j.ecoleng.2014.04.026.
3
Tian, Zhuang, Can Wang, and Min Ji. "Full-scale dissolved air flotation (DAF) equipment for emergency treatment of eutrophic water." Water Science and Technology 77, no. 7 (February 23, 2018): 1802–9. http://dx.doi.org/10.2166/wst.2018.046.
Анотація:
Abstract Eutrophication of urban rivers has caused severe environmental problems due to the pollution from point and diffuse sources. Although eutrophication can be alleviated by reducing the input to the river system, fast-treating terminal control technologies, especially under emergent situations, should be developed to reduce risks induced by eutrophication. The present study developed an emergency purification device based on dissolved air flotation (DAF) technology. After equipment commissioning and parameter optimization for applications in the field of engineering, the device was found to effectively remove total phosphorus, chlorophyll a, chemical oxygen demand, and turbidity in water by controlling the coagulant dosage and adjusting the gas-liquid mixing pump parameters. Dissolved air in water could enhance dissolved oxygen, and dissolved oxygen in polluted rivers could be raised from 0.2–2 mg/L to 3–3.5 mg/L. Removal of total nitrogen was poor because the majority of nitrogen contents were dissolved. Finally, DAF has been proven to be a promising technology due to its ease of implementation, low equipment investment requirement, and low operation cost.
4
Chung, Wayne, and Stephanie Young. "Evaluation of a chemical dissolved air flotation system for the treatment of restaurant dishwasher effluent." Canadian Journal of Civil Engineering 40, no. 12 (December 2013): 1164–72. http://dx.doi.org/10.1139/cjce-2012-0357.
Анотація:
Restaurant dishwashers consume a large quantity of fresh water and produce significant amounts of high strength oily wastewater which may cause serious problems when discharged into the sewer. An analysis of restaurant dishwasher effluent (RDE) from a busy upscale restaurant identified high levels of oil and grease, chemical oxygen demand (COD), biochemical oxygen demand (BOD), alkalinity, pH, and chlorine, but low levels of nitrogen and phosphorus. In this study, RDE was treated using an internationally patented chemical dissolved air flotation (chemical DAF) system. The chemical DAF system was designed so that coagulation, flocculation, and flotation processes could be carried out within the same reactor. The treatment system is therefore small and compact and suitable for use in restaurants where space is limited. The treatment performance of the chemical DAF was evaluated by determining optimal process conditions, contaminant removal efficiencies, and residual contaminant concentrations. It was found that removal efficiencies of 98.90%, 93.16%, 98.68%, 90.04%, and 88.20% could be achieved under optimal process conditions for turbidity, oil, TSS, BOD5, and COD, respectively. Total coliform and E. coli were not detected in either the raw dishwasher effluent or the treated dishwasher effluent due to the use of sodium hypochlorite as a dishwashing sanitizer. Water quality of the treated effluent met the criteria put forth in the Canadian Guidelines for Domestic Reclaimed Water for Use in Toilet and Urinal Flushing, with the exception of BOD5. Present findings suggest that chemical DAF is a promising treatment process for the removal of contaminants from restaurant dishwasher effluent.
5
Tong, Kun, Yi He Zhang, Jia Cai Xie, and Qi Hui Song. "Treatment of Heavy Oil Wastewater with Two Stages DAF Combined with ASP and I-BF Process - A Field Pilot Test." Advanced Materials Research 518-523 (May 2012): 2950–55. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.2950.
Анотація:
A field pilot test was constructed on a two stage Dissolved Air Floatation (DAF) combined with Activated Sludge Process (ASP) and Immobilized microorganism biological filter (I-BF) has been constructed in Liaohe oilfield, China to treat heavy oil wastewater with large amounts of dissolved recalcitrant organic compounds and low nutrient of nitrogen and phosphorus. By operating the system for 185 days, chemical oxygen demand (COD) removal rates were 67.9 % and 88.4 % in DAF and I-BF effluents, respectively. Environment Scanning electron microscope (ESEM) showed that large quantity of filamentous microorganisms was immobilized on carriers without causing foaming or bulking. This integrated system appeared to be a useful option for the treatment of heavy oil wastewater in Liaohe oil field.
6
Choi, Miyoung, Dong Whan Choi, Jung Yeol Lee, Young Suk Kim, Bun Su Kim, and Byoung Ho Lee. "Removal of pharmaceutical residue in municipal wastewater by DAF (dissolved air flotation)–MBR (membrane bioreactor) and ozone oxidation." Water Science and Technology 66, no. 12 (December 1, 2012): 2546–55. http://dx.doi.org/10.2166/wst.2012.429.
Анотація:
Growing attention is given to pharmaceutical residue in the water environment. It is known that pharmaceuticals are able to survive from a series of wastewater treatment processes. Concerns regarding pharmaceutical residues are attributed to the fact that they are being detected in water and sediment environment ubiquitously. Pharmaceutical treatment using a series of wastewater treatment processes of the DAF (dissolved air flotation)–MBR (membrane bioreactor)–ozone oxidation was conducted in the study. DAF, without addition of coagulant, could remove CODcr (chemical oxygen demand by Cr) up to over 70%, BOD 73%, SS 83%, T-N 55%, NH4+ 23%, and T-P 65% in influent of municipal wastewater. Average removal rates of water quality parameters by the DAF–MBR system were very high, e.g. CODcr 95.88%, BOD5 99.66%, CODmn (chemical oxygen demand by Mn) 93.63%, T-N 69.75%, NH4-N 98.46%, T-P 78.23%, and SS 99.51%, which satisfy effluent water quality standards. Despite the high removal rate of the wastewater treatment system, pharmaceuticals were eliminated to be about 50–99% by the MBR system, depending on specific pharmaceuticals. Ibuprofen was well removed by MBR system up to over 95%, while removal rate of bezafibrate ranged between 50 and 90%. With over 5 mg/l of ozone oxidation, most pharmaceuticals which survived the DAF–MBR process were removed completely or resulted in very low survival rate within the range of few micrograms per litre. However, some pharmaceuticals such as bezafibrate and naproxen tended to be resistant to ozone oxidation.
7
Del Nery, V., M. H. Z. Damianovic, R. B. Moura, E. Pozzi, E. C. Pires, and E. Foresti. "Poultry slaughterhouse wastewater treatment plant for high quality effluent." Water Science and Technology 73, no. 2 (September 26, 2015): 309–16. http://dx.doi.org/10.2166/wst.2015.494.
Анотація:
This paper assesses a wastewater treatment plant (WWTP) regarding the technology used, as well as organic matter and nutrient removal efficiencies aiming to optimize the treatment processes involved and wastewater reclamation. The WWTP consists of a dissolved air flotation (DAF) system, an upflow anaerobic sludge blanket (UASB) reactor, an aerated-facultative pond (AFP) and a chemical-DAF system. The removal efficiencies of chemical oxygen demand (COD) (97.9 ± 1.0%), biochemical oxygen demand (BOD) (98.6 ± 1.0%) and oil and grease (O&G) (91.1 ± 5.2%) at the WWTP, the nitrogen concentration of 17 ± 11 mgN-NH3 and phosphorus concentration of 1.34 ± 0.93 mgPO4−3/L in the final effluent indicate that the processes used are suitable to comply with discharge standards in water bodies. Nitrification and denitrification tests conducted using biomass collected at three AFP points indicated that nitrification and denitrification could take place in the pond.
8
Tetteh, Emmanuel Kweinor, and Sudesh Rathilal. "INVESTIGATING DISSOLVED AIR FLOTATION FACTORS FOR OIL REFINERY WASTEWATER TREATMENT." CBU International Conference Proceedings 6 (September 25, 2018): 1173–77. http://dx.doi.org/10.12955/cbup.v6.1311.
Анотація:
The global demand for petrochemical and petroleum industry products unavoidably generates large volumes of oil refinery wastewater (ORW). The complete treatment, reclamation and disposal of the ORW to an acceptable environmental limit is currently a challenge to most of the petroleum industries. With the current development in conventional treatment methods viz. coagulation, dissolved air flotation (DAF), and biological and membrane separation processes. DAF, which is well-established separation process, effectively employs microbubbles as a carrier phase for separation. Although, DAF is frequently used in combined water and wastewater treatment plants, its fundamental characteristics and operational parameters have not yet been fully investigated for the treatment of ORW. In this study, the correlation and effects of the parameters understudy (coagulant dosage, air saturator pressure, air-water ratio and rising rate) on chemical oxygen demand, soap oil and grease, turbidity and total suspended solids removal from ORW were examined experimentally using a laboratory DAF system. The results showed that increasing the saturator working pressure and the rising rate had less effect on the system, than increasing the air-water ratio. The agglomeration of the oil droplets was found to depend solely on the polyaluminum sulphate (PAS) dosage to destabilize the oil droplets. The DAF treatability performance showed over 80% removal of the contaminants at optimum conditions of pH of 5, PAS dosage of 10 mg/L, rising rate of 15 minutes, air saturator pressure of 300-500 kPa, and air-water ratio of 5-15%. The PAS dosage was found to be the most significant factor. Therefore, a moderate increase of the PAS dosage under these optimum conditions will increase the DAF efficiency in the treatment of ORW.
9
Jamieson, Bryan Lee, Alex Augusto Gonçalves, and Graham A. Gagnon. "Evaluation of treatment options for Atlantic Canadian seafood processing plant effluentA paper submitted to the Journal of Environmental Engineering and Science." Canadian Journal of Civil Engineering 37, no. 1 (January 2010): 167–78. http://dx.doi.org/10.1139/l09-127.
Анотація:
The purpose of this study was to evaluate different effluent treatment options for Atlantic Canadian seafood processing plants. Bench-scale testing with a 25-mesh screen, sedimentation (SED), and dissolved air flotation (DAF) was conducted. Treatment by SED and DAF was successful in reducing contaminant concentrations with maximum observed percent reductions: biochemical oxygen demand, BOD5 (90%); chemical oxygen demand, COD (60%); turbidity (99%); total suspended solids, TSS (95%); and ammonia nitrogen, NH3-N (50%). Bench-scale 25-mesh screen runs for select effluent types showed poor reduction efficiencies and appeared to provide inadequate removal of contaminants. Sedimentation and DAF using alum were effective at removing solids but less effective at removing soluble effluent components. Improved performance may be possible with further treatment technology optimization on an effluent specific basis.
10
Azhar, Muhammad Rizwan, Paul Nolan, Keith Cadee, and Mehdi Khiadani. "Chemical-Free Biologically Enhanced Primary Treatment of Raw Wastewater for Improved Capture Carbon." Water 14, no. 23 (November 24, 2022): 3825. http://dx.doi.org/10.3390/w14233825.
Анотація:
Conventional wastewater treatment processes require extensive energy inputs for their operations. Biologically enhanced primary treatment (BEPT) is a promising technology to capture incoming organics that may be utilized to produce biogas and potentially hydrogen with further downstream processing. This study involved a biologically enhanced primary treatment (BEPT) of raw wastewater at bench and pilot-scale using activated sludge (AS) addition and dissolved air flotation (DAF) using raw wastewater at a municipal wastewater facility in Western Australia with average chemical oxygen demand of ~800 mg/L. The results of pilot-scale testing showed an improved removal performance for total chemical oxygen demand (COD-T), soluble chemical oxygen demand (COD-S), and total suspended solids (TSS) compared to conventional primary treatment (PT). Specifically, average COD-T, COD-S and TSS removals for BEPT were 33.3%, 13.5% and 45%, respectively which was 10%, 100% and 6% higher than PT. Moreover, the sludge produced from BEPT had a high solids content of 4.8 g/L, which might not need further thickening prior to anaerobic digestion. It is important to note that no chemicals were used during BEPT testing, which makes the process very cost-effective.
11
Sandbank, E., and L. J. van Vuuren. "Microalgal Harvesting by in situ Autoflotation." Water Science and Technology 19, no. 12 (December 1, 1987): 385–87. http://dx.doi.org/10.2166/wst.1987.0178.
Анотація:
Dissolved Air Flotation (DAF) principles were applied to harvest microalgae from high rate algal pond (HRAP) effluents in a highly simplified system which consisted of an open channel and a dosing pump only. Polyelectrolyte solution is dosed into the channel through a diffuser in the vicinity of a paddle wheel, where rapid mixing occurs. Slow mixing takes place in the channel. While flocs grow, oxygen bubbles resulting from algae photosynthetic activity are entrapped. Floating flocs are removed manually at the end of the channel. Removal efficiencies of 90% were obtained at a 10 mg polyelectrolyte dose. The float had 4 to 6% solids which dewatered easily to 10% solids.
12
Widianingtias, Mitria, Shinobu Kazama, Sawangjang Benyapa, and Satoshi Takizawa. "Assessment of Water Reclamation and Reuse Potential in Bali Province, Indonesia." Water 15, no. 14 (July 20, 2023): 2642. http://dx.doi.org/10.3390/w15142642.
Анотація:
Bali Province, Indonesia, experiences serious water shortages and groundwater over-abstraction due to rapidly increasing water demand. Therefore, this study aimed to assess the potential for water reclamation and reuse in Bali Province, focusing on the operational performance of two wastewater treatment plants (WWTPs). Although the Suwung WWTP could increase its treatment capacity to produce reclaimed water for irrigation and landscape, there are multiple management issues to be addressed, including fluctuating water demand, limited customer base beyond hotels, concerns about water quality and safety, and cultural perceptions of reclaimed water. In addition, despite the organic loading rates being lower than the design value, the treatment performance of the Suwung WWTP was found to be significantly lower than that of the ITDC WWTP, which achieved high BOD, COD, and TSS removal rates by performing good maintenance of aerators and post-treatment based on dissolved air flotation (DAF). Causal loop analysis indicates that aerator malfunctioning causes multiple problems, such as low dissolved oxygen, poor BOD removal, sludge carryover, and low sludge concentrations. Therefore, regular maintenance of aerators, as well as the development of aerators robust against malfunctioning, are fundamental to producing effluents from stabilization ponds that meet the requirements for irrigation and landscape reuse.
13
Reis, Rafaela Inês dos, and Diego De Souza Sardinha. "Transporte fluvial de sedimentos e nutrientes a montante do Reservatório da Hidrelétrica Caconde, bacia do Alto Rio Pardo (MG)." Revista Brasileira de Geografia Física 14, no. 5 (September 30, 2021): 2646. http://dx.doi.org/10.26848/rbgf.v14.5.p2646-2663.
Анотація:
Um dos principais mecanismos de perda de nutrientes ocorre por meio da erosão hídrica do solo. Como o Rio Pardo é o principal afluente do Reservatório da Hidrelétrica Caconde, utilizado para geração de energia elétrica, captação de água, pesca e lazer, este trabalho avaliou o transporte fluvial de sedimentos e nutrientes à montante deste. Para isso, as águas foram monitoradas uma vez por mês, entre maio de 2018 a abril de 2019 para os seguintes parâmetros, temperatura, pH, condutividade elétrica, oxigênio dissolvido, turbidez, nitrato, fosfato, sulfato, sólidos totais (ST), dissolvidos (STD) e em suspensão (STS). Os resultados demonstram que a bacia apresenta qualidade da água dentro dos padrões para a maioria dos parâmetros analisados, no entanto, para pH nos meses de junho (5,1) e abril (5,4) e oxigênio dissolvido nos meses de maio (3,0 mg/L) e setembro (4,6 mg/L) as concentrações estão abaixo do limite permitido. As rochas da bacia não possuem grande quantidade de nitrato, fosfato e sulfato em sua composição mineralógica, no entanto, a aplicação de fertilizantes nitrogenados, fosfatados e sulfatados em áreas agrícolas podem contribuir com a remoção de partículas e íons do solo influenciando no transporte fluvial anual de sedimentos (STD = 24,0x103 t, STS = 41,8x103 t e ST = 65,9x103 t) e nutrientes (NO3- = 3,0x103 t, SO42- = 5,6x103 t e PO43-= 480 t). Estes elementos quando adentram em um ambiente lêntico, podem ocasionar efeitos adversos como assoreamento e eutrofização, diminuindo o volume e a qualidade da água utilizável. Sediments and nutrients fluvial transport upstream Caconde Hydroelectric Dam, Alto Rio Pardo (MG) basin A B S T R A C TOne of the main mechanisms of nutrient loss in the soil occurs through water erosion. As the Pardo River is the main tributary for Caconde Hydroelectric Reservoir, used for electricity generation, water collection, fishing and recreation, this work evaluated sediments and nutrients fluvial transport upstream the reservoir. Thus, waters were monitored once a month, between May 2018 and April 2019 for the following parameters, temperature, pH, electrical conductivity, dissolved oxygen, turbidity, nitrate, phosphate, sulfate, total solids (TS), dissolved (TDS) and in suspension (TSS). The results demonstrate that the basin presents water quality within the standards for most of the analyzed parameters, however, for pH in June (5.1) and April (5.4) and dissolved oxygen in May (3.0 mg.L-1) and September (4.6 mg.L-1) concentrations were below the permitted limit. The basin rocks doesn't present large amounts of nitrate, phosphate and sulfate in their mineralogical composition, however, nitrogen, phosphates and sulfates fertilizers application in agricultural areas can contribute to the particles and ions removal from the soil, therefore influencing sediments (STD = 24.0x103 t, STS = 41.8x103 t and ST = 65.9x103 t) and nutrients (NO3- = 3.0x103 t, SO42- = 5.6x103 t and PO43- = 480 t) annual river transport. These elements, in a lentic environment, can cause adverse effects such as siltation and eutrophication, decreasing volume and quality of the usable water.Keywords: defluvium, river base flow, specific transport, dilution, land use.
14
Penetra, R. G., M. A. P. Reali, E. Foresti, and J. R. Campos. "Post-Treatment of Effluents from Anaerobic Reactor Treating Domestic Sewage by Dissolved-Air Flotation." Water Science and Technology 40, no. 8 (October 1, 1999): 137–43. http://dx.doi.org/10.2166/wst.1999.0405.
Анотація:
This paper presents the results of a study performed with a lab-scale dissolved-air flotation (LSDAF) unit fed with previously coagulated effluent from a pilot scale up-flow anerobic sludge blanket (UASB) reactor treating domestic sewage. Physical operational conditions for coagulation (rapid mix) and flocculation/flotation were maintained constant. Chemical (FeCl3) dosages ranged from 30 to 110 mg.l−1. The effect of pH was also verified in the range of 5.1 to 7.6 for each dosage. Best results were achieved for 65 mg.l−1 of FeCl3 and pH values between 5.3 and 6.1. For these conditions, the removal efficiencies obtained in the LSDAF unit were: between 87% and 91% for chemical oxygen demand (COD), between 95% and 96% for total phosphate (TP), 94% for total suspended solids (TSS), between 96% and 97% for turbidity (TU), between 90% and 93% for apparent color (AC) and more than 96% for sulfide (S). For the UASB-DAF system, global efficiencies would be around 98% for COD, 98% for TP, 98.4% for TSS, 99.3% for TU and 98% for AC. The stripped gases treatment is desirable.
15
Dada, Saubana Olorunsola, Chidambaram Thamariselvan, Mahmood Jebur, and Sumith Ranil Wickramasinghe. "Innovative Approaches to Poultry Processing Wastewater Treatment: The Stainless Steel Ultrafiltration Membrane as a Viable Option." Membranes 13, no. 11 (November 11, 2023): 880. http://dx.doi.org/10.3390/membranes13110880.
Анотація:
In pursuit of sustainability, we explored replacing conventional dissolved air floatation (DAF) in poultry processing wastewater (PPW) treatment with a precisely tuned 0.02 µm stainless-steel ultrafiltration (SSUF) membrane. SSUF is a robust, homogenously porous membrane with strong chemical resistance, ease of cleaning, and exceptional resistance to organic fouling. Unlike polymeric membranes, it can be regenerated multiple times, making it a cost-effective choice due to its compatibility with harsh chemical cleaning. The PPW used for the study was untreated wastewater from all processing units and post-initial screening. Our study revealed the SSUF membrane’s exceptional efficiency at eliminating contaminants. It achieved an impressive removal rate of up to 99.9% for total suspended solids (TSS), oil, grease, E. coli, and coliform. Additionally, it displayed a notable reduction in chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total Kjeldahl nitrogen (TKN), up to 90%, 76%, and 76%, respectively. Our investigation further emphasized the SSUF membrane’s ability in pathogen removal, affirming its capacity to effectively eradicate up to 99.99% of E. coli and coliform. The measured critical flux of the membrane was 48 Lm−2h−1 at 38 kPa pressure and 1.90 m/s cross-flow velocity. In summary, our study highlights the considerable potential of the SSUF membrane. Its robust performance treating PPW offers a promising avenue for reducing its environmental impact and advocating for sustainable wastewater management practices.
16
Dizayee, Kasro Kakil Hassan, Adil Mohammed Raheem, and Simon J. Judd. "The Cost Benefit of Refinery Effluent Pretreatment Upstream of Membrane Bioreactors." Membranes 13, no. 8 (August 1, 2023): 715. http://dx.doi.org/10.3390/membranes13080715.
Анотація:
The established classical method of treating oil refinery effluent is flotation followed by biological treatment. Membrane bioreactors (MBRs) offer more advanced treatment, producing a clarified and potentially reusable treated effluent, but demand robust pretreatment to remove oil and grease (O&G) down to consistent, reliably low levels. An analysis of a full-scale conventional oil refinery ETP (effluent treatment plant) based on flotation alone, coupled with projected performance, energy consumption and costs associated with a downstream MBR, have demonstrated satisfactory performance of flotation-based pretreatment. The flotation processes, comprising an API (American Petroleum Institute) separator followed by dissolved air flotation (DAF), provided ~90% removal of both total suspended solids (TSS) and O&G coupled with 75% COD (chemical oxygen demand) removal. The relative energy consumption and cost of the pretreatment, normalised against both the volume treated and COD removed, was considerably less for the API-DAF sequence compared to the MBR. The combined flotation specific energy consumption in kWh was found to be almost an order of magnitude lower than for the MBR (0.091 vs. 0.86 kWh per m3 effluent treated), and the total cost (in terms of the net present value) around one sixth that of the MBR. However, the nature of the respective waste streams generated and the end disposal of waste solids differ significantly between the pretreatment and MBR stages.
17
Penetra, R. G., M. A. P. Reali, and J. R. Campos. "Influence of flocculation conditions in the performance of an experimental domestic sewage treatment plant consisting of an anaerobic expanded bed reactor followed by dissolved air flotation." Water Science and Technology 48, no. 6 (September 1, 2003): 285–93. http://dx.doi.org/10.2166/wst.2003.0414.
Анотація:
This paper presents the results of a study performed with an experimental domestic sewage treatment plant (240 m3.d-1 flow) consisting of expanded bed anaerobic reactor (EBAR) followed by dissolved air flotation (DAF) unit. For the flotation step, the anaerobic reactor effluent was previously coagulated with 50 mgFeCl3.l-1 and flocculated under different conditions (mean velocity gradient, Gf, and flocculation time, Tf). The Gf values were from 60 to 100 s-1 associated with 13 and 20 min Tf values. During the tests, the following operational conditions of the flotation unit were maintained: chemical addition (50 mgFeCl3.l-1), 18% recirculation rate associated with a pressure of 450 ± 10 kPa in the saturation chamber and overflow rate of 180 m3.mÐ2.d-1. Temperature ranged from 23.8¡C to 30.01/4C. Best results were achieved for Gf = 80 s-1 and Tf = 20 min. For these conditions, the DAF unit removal efficiencies were: 94.4% for chemical oxygen demand (with 53 mg.l-1 COD residual), 87% for phosphorus (with 0.80 mgP.l-1 residual), 96.7% for total suspended solids (with 9 mg.l-1 TSS residual) and 96.4% for turbidity (with 12.9 NTU residual), when the anaerobic reactor effluents have worst quality during the whole day.
18
Żyłka, Radosław, Wojciech Dąbrowski, Paweł Malinowski, and Beata Karolinczak. "Modeling of Electric Energy Consumption during Dairy Wastewater Treatment Plant Operation." Energies 13, no. 15 (July 22, 2020): 3769. http://dx.doi.org/10.3390/en13153769.
Анотація:
The intensification of biological wastewater treatment requires the high usage of electric energy, mainly for aeration processes. Publications on energy consumption have been mostly related to municipal wastewater treatment plants (WWTPs). The aim of the research was to elaborate on models for the estimation of energy consumption during dairy WWTP operation. These models can be used for the optimization of electric energy consumption. The research was conducted in a dairy WWTP, operating with dissolved air flotation (DAF) and an activated sludge system. Energy consumption was measured with the help of three-phase network parameter transducers and a supervisory control and data acquisition (SCADA) system. The obtained models provided accurate predictions of DAF, biological treatment, and the overall WWTP energy consumption using chemical oxygen demand (COD), sewage flow, and air temperature. Using the energy consumption of the biological treatment as an independent variable, as well as air temperature, it is possible to estimate the variability of the total electric energy consumption. During the summer period, an increase in the organic load (expressed as COD) discharged into the biological treatment causes higher electric energy consumption in the whole dairy WWTP. Hence, it is recommended to increase the efficiency of the removal of organic pollutants in the DAF process. An application for the estimation of energy consumption was created.
19
Jaya Chithra S. K., Saranya S. B., V. Viji, R. Pradeep Kumar, Savitha P., and Sojomon Mathew. "Comparative Study of Water Quality from Two Major Dam Reservoirs of Thiruvananthapuram District, Kerala." UTTAR PRADESH JOURNAL OF ZOOLOGY 44, no. 22 (October 26, 2023): 44–52. http://dx.doi.org/10.56557/upjoz/2023/v44i223715.
Анотація:
Neyyar Dam and Aruvikkara Dam are two major dam reservoirs located at Thiruvananthapuram District of Kerala State. Physicochemical parameters of water from these two dam reservoirs were studied and compared during pre-monsoon and monsoon period from April 2018 to July2018.Water samples were collected from different sampling stations of the reservoirs and analyzed as per standard methods of APHA (2012). Water from Neyyar dam shows maximum value of all physicochemical parameters compared to water from Aruvikkara dam in the present study period. Water temperature, Total Dissolved Solids, Total Suspended Solids, pH, free CO2, Biological Oxygen Demand and Total hardness were maximumin pre monsoon season and Turbidity, Productivity and Dissolved Oxygen were maximum in monsoon season at both sites. Present study reveal that water from Neyyar dam is more polluted than water from Aruvikkara.
20
Kong, Feng Qin, Yu Wang, and Yong Cheng. "Analysis of the DO Distribution and the Influencing Factors at the Downstream of Large Dam." Advanced Materials Research 919-921 (April 2014): 1206–10. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.1206.
Анотація:
During the discharge of high dam, strong collision occurred along with the energy dissipation of the high velocity aerated flow. A great deal of air incorporated into the water and formed bubbles for the water was tumbling and gyration tempestuously. A large amount of air was released from the bubbles under the action of the hydrostatic pressure, and dissolved in the water, as a result, total dissolved gas (TDG) supersaturation was caused in the water. However, the supersaturation of the TDG has some important adverse effects on the surivival and reproduction of the aquatic, eapecially the fish. This paper analysised the longitudinal distribution and vertical distribution of the total dissolved oxygen (DO) saturation and the possible causing factors through using the measured data on the discharge in the Three - Gorge cascade hydropower station, combine with the theory of the water TDG supersaturation caused by the outflow from dam. The result shows that, the construction and operation of the cascade hydropower station can lead to the higher concentration of the total dissolved oxygen in the water,and even the supersaturation. Besides, total oxygen saturation decresde with the increasing of the water depth. Furthermore, the water level in front of the dam and the energy dissipating mode have some important effect on the total dissolved oxygen supersaturation.
21
Kumar Sepat, Manoj, and Hanumant Singh Chouhan. "Assessment of Water Parameters of Upper Kodera Dam in Mount Abu after Rainfall." Ecology, Environment and Conservation 29 (2023): 373–77. http://dx.doi.org/10.53550/eec.2023.v29i02s.060.
Анотація:
The current research aims to investigate the effects of physicochemical factors on water quality, particularly during the summer at Upper Kodera Dam in Mount Abu (Raj), India. For the investigation of physicochemical factors such such as water and air temperature, pH, transparency, total hardness, dissolved oxygen, total alkalinity, and chemical oxygen demand, water samples from the dam were taken. The acquired findings were compared to WHOBIS (World Health Organization and Bureau of Indian Standard) values permitted limits for drinking water. A few parameters at various stations were found to be close to the allowable limits. With reference to the analysed criteria, the current study identified how rainfall affects the water quality of Upper Kodera Dam water. Samples of 10 water were taken from Upper Kodra Dam between May 2021 and November 2022. Total hardness, Alkalinity, chloride, pH, total dissolved solids, iron, dissolved oxygen, fluoride, nitrate, sulphate, chromium, iron, chromium, and MPN of coliforms are among the biological and physicochemical parameters that were examined. According to the report, the current water supply needs urgent remediation since the water quality is subpar.
22
Kim, Byung R., and Charles E. Bohac. "Comparing Options for Improving Dissolved Oxygen Below Hydropower Dam." Journal of Energy Engineering 115, no. 2 (August 1989): 63–77. http://dx.doi.org/10.1061/(asce)0733-9402(1989)115:2(63).
23
Ilechukwu, Ifenna, Tolulope Abisola Olusina, and Odinaka Chidinma Echeta. "Physicochemical analysis of water and sediments of Usuma Dam, Abuja, Nigeria." Ovidius University Annals of Chemistry 31, no. 2 (July 1, 2020): 80–87. http://dx.doi.org/10.2478/auoc-2020-0015.
Анотація:
AbstractUsuma Dam is the major source of potable water in the Federal Capital Territory, Abuja, Nigeria. The physicochemical properties of water and sediment of the dam was assessed in this study to determine its quality. Electrical conductivity, pH, nitrate, phosphate, total dissolved solids, total suspended solids, turbidity, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, chloride, total hardness, phosphate, nitrate and sulfate were determined in the water samples. Total organic matter, total organic carbon and particle size were among the parameters analyzed in sediments. The parameters were within recommended limits except for biochemical oxygen demand and chemical oxygen demand which were more than the recommended limit of 10 mg/L and 30 mg/L respectively. The total organic matter and the total organic carbon in the sediment samples were between 1.56±0.27 – 2.85±0.20 % and 0.13±0.03 – 0.96±0.03 % respectively. The particle size was in the following order: sand > silt > clay. The results of this study confirmed the presence of high organic and inorganic matter in the dam from non-point pollution sources occasioned by storm water from poorly planned settlements around the dam and runoffs from agricultural practices.
24
Singodia, R. R., N. K. Nirmal, and P. J. John. "Assessment of water quality of Kot Dam, Rajasthan, India, using water quality index." Journal of Environmental Biology 45, no. 2 (March 23, 2024): 171–81. http://dx.doi.org/10.22438/jeb/45/2/mrn-5180.
Анотація:
Aim: To assess the water quality of Kot Dam, located in the Jhunjhunu district of Rajasthan, India. Methodology: Physico-chemical parameters of water quality were monitored for two years (July 2021 to June 2023). The Water Quality Index (WQI), a widely accepted mathematical expression used to understand the trend in the quality of water bodies, was calculated based on the analysis of physicochemical parameters, including pH, total dissolved solids, hardness, alkalinity, dissolved oxygen, biological oxygen demand, chloride, sulphate, nitrate, calcium, magnesium, conductivity, and fluoride. Results: The site-wise and season-wise analysis of WQI revealed that Dam water was polluted due to organic pollutants, agricultural runoff, and waste disposal by local people, especially during summer (WQI=87.18) and monsoon seasons (WQI=85.38). Interpretation: Anthropogenic activities adversely affected the water quality at sample station (S1) of Kot Dam. Key words: Anthropogenic activities, Bray-Curtis Similarity Index, Dendrogram, Kot dam, Water quality
25
KAMETANI, Hitoshi, Katsuaki HORIE, Noriaki KOUDA, Hideki KUMA, Kousuke MATSUMOTO, Kazuhiro UCHIMURA, Kenichi KOMORI, Singo MASUKI, and Hirohito AZUMA. "Development of a dissolved oxygen improvement system for dam lake." Transactions of the JSME (in Japanese) 83, no. 853 (2017): 17–00147. http://dx.doi.org/10.1299/transjsme.17-00147.
26
Deribew, Ketema, Berhanu Erko, Seid Tiku Mereta, Delenasaw Yewhalaw, and Zeleke Mekonnen. "Assessing Potential Intermediate Host Snails of Urogenital Schistosomiasis, Human Water Contact Behavior and Water Physico-chemical Characteristics in Alwero Dam Reservoir, Ethiopia." Environmental Health Insights 16 (January 2022): 117863022211235. http://dx.doi.org/10.1177/11786302221123576.
Анотація:
Introduction: Urogenital schistosomiasis is one of public health problems in lowland areas of Ethiopia. The disease is caused by Schistosoma haematobium. Freshwater Bulinus snails are intermediate hosts for the parasite transmission. The aim of the study was to assess intermediate host snails of urogenital schistosomiasis, human water contact behavior and physico-chemical characteristics of Alwero Dam reservoir. Methods: Bulinus snails were sampled from 12 sites of Alwero Dam. Bulinus snails were collected, identified and examined for natural schistosome infections. A total of 206 people were interviewed to determine human water contact behavior. The water temperature, pH, dissolved oxygen, total dissolved solid, salinity and conductivity of the water were determined. Results: Of 1125 Bulinus snails collected, 72 (6.4%) were infected with echinostome cercariae but none of them were infected with schistosome cercariae. The abundance of Bulinus species did not show significant variation across seasons ( P = .61). Occurrence of Bulinus species was significantly higher in stony substratum than sandy substratum ( P = .01). Of the total 206 participants, 119 (57.8%) had water contact activities like washing clothes, bathing or swimming. Majority of respondents (70.0%) reported that they visited the dam reservoir once or twice a week, while 16.5% and 13.6% reported that they visited the dam 3 to 5 times a week and daily, respectively. Moreover, 72.3% of the respondents had reported they had history of urogenital schistosomiasis infection. The mean water temperature, pH, dissolved oxygen, total dissolved solid, electric conductivity, and salinity of the dam water was 28.6°C, 7.07, 5.75 mg/l, 90.0 ppm, 124.8 µS/cm, and 50.0 ppm, respectively. Conclusion: At Alwero Dam, Bulinus snails were highly abundant and the human water contact activities were frequent. Therefore, the community awareness creation should be made to reduce water contact with snail infested water to prevent risk of urogenital schistosomiasis infection.
27
Mangi, Halima O., Simon M. Onywere, and Esther C. Kitur. "Fish Productivity Response to Water Quality Variations: A Case Study of Nyumba ya Mungu Dam, in Pangani Water Basin, Tanzania." International Journal of Ecology 2023 (July 24, 2023): 1–11. http://dx.doi.org/10.1155/2023/7353898.
Анотація:
Fish habitat degradation, such as water pollution due to the rapid expansion of incompatible land uses, is one of the noteworthy challenges to freshwater ecosystems. Elevated contents of nutrients and contaminants in water are some of the imperative challenges. This research was conducted to investigate the link between water qualities and fish productivity in the Nyumba ya Mungu Dam, whose fishery potential had decreased by 95% between 1972 and 2018. Physicοchemical characteristics, namely, temperature, pH, dissolved oxygen (DO), turbidity, total nitrogen, total phosphorus, chlorophyll a, and the water depth of fishing net location, were assessed following standard procedure. Fish catches per unit effort representing fish biomass/productivity were monitored for twelve months from January to December 2019. Pearson’s correlation analysis indicated that fish catch per unit effort was positively and significantly correlated with turbidity (r = 0.461, P < 0.01) and TP (r = 0.405, P < 0.01). Stepwise multiple regression model results indicated that turbidity, dissolved oxygen, and the depth of the fishing net location are the statistically significant predictors of fish catch per unit effort which represented fish biomass. Findings further indicated that the model combining turbidity and dissolved oxygen predicted a 24% change in fish catch per unit effort, whereas turbidity, dissolved oxygen, and the depth of fishing net location contributed a 28.9% change in fish catch per unit effort. In conclusion, fish productivity in the NMD is limited by organic matter availability and nutrient levels that cause algae bloom occurrence. Turbidity is an indicator of organic matter availability and the effect of algae bloom on fish productivity. Inflow of nutrients to the dam nourishes the algae biomass, thus creating vicious cycles on fish productivity as fish species in the dam failed to take advantage of high primary production by algae.
28
Saraswat, Heena, and Meenakshi Solanki. "WATER QUALITY ASSESSMENT OF PUNASA DAM (INDIRA SAGAR DAM), MADHYA PRADESH." International Journal of Advanced Research 9, no. 02 (February 28, 2021): 501–8. http://dx.doi.org/10.21474/ijar01/12476.
Анотація:
The Indirasagar Dam (Punasa Dam) is a multipurpose key project of Madhya Pradesh on the Narmada river at Narmada Nagar in Khandwa (Tehsil of West Nimar district) Madhya Pradesh in India.The physical and chemical properties of water including temperature, pH, transparency, dissolved oxygen, biological oxygen demand, hardness, nitrate, calcium and phosphorus concentration, were monitored from October 2018 to September 2019. The physical and chemical parameters were analyzed as per APHA, revealed that there were fewer variations in the physicochemical parameters and results received through the entire one year of study showed that the status of water quality is quite normal and within the permissible limit as mentioned with ISI.Moreover, according to the findings of this research and their comparison with the national and international water quality guidelines/standards, it could be said that the water quality of Punasa dam during the study period was acceptable. However, due to the changes occurred in nitrate and phosphorus and extensive development of eutrophication problem, accurate and continuous evaluation of water quality in this reservoir is deemed necessary.
29
Fu, Jin Xiang, Jun Shang, and Yu Hua Zhao. "Simultaneous Removal of Iron, Manganese and Ammonia from Groundwater in Single Biofilter Layer Using BAF." Advanced Materials Research 183-185 (January 2011): 442–46. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.442.
Анотація:
Biological aerated filter (BAF) was employed to remove iron, manganese and ammonia from groundwater. The filter was in continuous operation under hydraulic loading of 3m3/m2.h. The influence of air-water ratio, the removal effects of iron, manganese and ammonia respective, and the oxidation of the three pollutants, the change of dissolved oxygen along the filter depth were investigated in this research. And the results was obtained, that the optimal air-water ratio was determined by 3, which made the dissolved oxygen concentration in the filter central be 4.75mg/l, and the removal of iron, manganese and ammonia be above 90%, 99% and 87%, respectively. The efficient removal of manganese occurred in the central and lower parts of the filter. More iron was oxidated at the upper 0.75m of the filter, and the oxidation velocity of manganese and ammonia would be limited, when the inlet iron concentration was higher. Nitrification process consumed more dissolved oxygen, which made dissolved oxygen concentration decrease along the filter depth from 0 to 1.25m. The demand of filtration depth is 1.6m, for simultaneous removal.
30
Barnard, James L., and P. G. J. Meiring. "Dissolved Oxygen Control in the Activated Sludge Process." Water Science and Technology 20, no. 4-5 (April 1, 1988): 93–100. http://dx.doi.org/10.2166/wst.1988.0157.
Анотація:
The increased cost of energy and the need for biological removal of plant nutrients resulted in a renewed interest in dissolved oxygen control in the activated sludge process. Back-up systems are required to prevent overaeration during the night which may be detrimental to the nutrient removal process. Full-scale experience with both fine bubble and surface aerators are described.
31
Luo, Xia, Xinyi Xiang, Guoyi Huang, Xiaorui Song, Peijia Wang, and Kaidao Fu. "Bacterial Abundance and Physicochemical Characteristics of Water and Sediment Associated with Hydroelectric Dam on the Lancang River China." International Journal of Environmental Research and Public Health 16, no. 11 (June 7, 2019): 2031. http://dx.doi.org/10.3390/ijerph16112031.
Анотація:
Research on bacterial abundance in water column and sediment of dammed rivers remain poorly understood, despite their importance to biogeochemical processes, benthic ecology, and bioremediation. The present study investigates the water and sediment bacteria by epifluorescence microscopy in the reservoir (above the dam site), as well as in the downstream river stretches (below-dam site) at the middle reach of Lancang River during the wet, the normal and the dry seasons. The results demonstrated that the reservoir operating regime (water discharge variations) and strong precipitation promoted significant differences in the conditions of the river below the dam, especially for the concentration of dissolved oxygen, redox potential, electric conductivity, turbidity, and total dissolved solids in water and concentration of microbial activity in sediment. The seasonal variations were also key factors influencing water quality at the below-dam sampling sites. Nutrients concentration did not induce a significant response in bacterial abundance when inorganic nutrients were sufficient. Bacterial density in sediment was regulated by hydropower-related discharge, particle size, and type of sediments, while bacterial abundances in water were strongly linked with the physicochemical characteristics of the water, such as total dissolved solids and conductivity.
32
Naval, Ramesh M. "Study of Drinking Water Quality Parameters of Jaykwadi Dam." International Journal for Research in Applied Science and Engineering Technology 9, no. VII (July 30, 2021): 2971–73. http://dx.doi.org/10.22214/ijraset.2021.37039.
Анотація:
This study is restricted in terms of water quality for drinking purpose. Various Physico-chemical Parameters like pH, conductivity. TDS are measured in laboratory by using digital pH meter, digital conductivity meter and TDS recording kit. By sung standard laboratory methods the Parameters Such as sodium, and potassium by Flame photometry. Calcium, Magnesium, Sodium, Potassium, Sulphate, Nitrate, and Iron were estimated in the Laboratory. Total dissolved solids, TDS, was measured by evaporation method. Biochemical oxygen demand, BOD, represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (in presence of oxygen) conditions at a specified temperature. BOD was measured by sodium thiosulphate titration method. Chemical oxygen demand, COD, was measured by titration of potassium dichromate and sodium thiosulphate.
33
Baskaran, K., P. H. Scott, and M. A. Connor. "Biofilms as an Aid to Nitrogen Removal in Sewage Treatment Lagoons." Water Science and Technology 26, no. 7-8 (October 1, 1992): 1707–16. http://dx.doi.org/10.2166/wst.1992.0614.
Анотація:
A pilot study of sewage treatment lagoons near Melbourne indicated that the best way to enhance nitrogen removal in such lagoons was to promote nitrification. Combined algal/bacterial biofilms grown on surfaces immersed in the lagoons showed potential for greatly increasing the extent of nitrification. A laboratory study was undertaken to determine the effect of pH, dissolved oxygen concentration, temperature and other factors on the nitrifying capabilities of such biofilms; effective nitrification was observed at temperatures down to 10°C, at pH's down to 5.5 and at dissolved oxygen levels down to 2.5 mg/L. Tanks containing biofilm-coated plates nitrified much more effectively than tanks containing only suspended microbial growths. At dissolved oxygen levels of 2-3 mg/L, up to 30% of the ammonia-nitrogen fed to tanks containing biofilm-coated plates was removed by denitrification. Photosynthetic activity in the biofilm greatly enhanced nitrification efficiencies at low dissolved oxygen levels.
34
Oladeji, S. O. "Evaluation of physicochemical parameters in wastewater from Muhammad Ayuba dam in Kazaure, Jigawa state, Nigeria." Archives of Agriculture and Environmental Science 5, no. 4 (December 25, 2020): 482–88. http://dx.doi.org/10.26832/24566632.2020.050408.
Анотація:
Evaluation of physicochemical parameters namely alkalinity, biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, dissolved oxygen (DO), hardness, pH and total dissolved solids (TDS) in the wastewater samples collected from Muhammad Ayuba dam in Kazaure, Nigeria. The study was conducted during harmattan season for a period of three months from November, 2019 – January, 2020. All the parameters were analysed using conventional methods. The results showed their concentrations were in the range of 1.00 – 1.50 mg/L for alkalinity, 3.00 – 3.45 mg/L for BOD, 12.45 – 24.00 mg/L for COD, 745 – 1200 µS/cm for conductivity, 5.50 – 6.30 mg/L for DO, 1.82 – 2.45 mg/L for hardness, 7.20 – 7.90 for pH and 410 – 440 mg/L for TDS. The concentrations of these parameters in the wastewater were observed less than World Health Organization (WHO) tolerance limits with exception of electrical conductivity that was above 1000 µS/cm after four weeks of investigation. This study revealed gradual build-up of various ions in the dam water due to the mixing of contaminated wastewater from the adjacent community. Therefore, the periodical monitoring of different physicochemical parameters of the dam water should put in place as to evaluate their environmental impacts and possible potential risks.
35
Köse, Esengül. "A GIS Based Study to Investigate of the Ecological Impacts of Successive Dams on Surface Water Quality: A Review of the Sakarya Basin, Türkiye." Биология внутренних вод, no. 6 (November 1, 2023): 762–63. http://dx.doi.org/10.31857/s0320965223060153.
Анотація:
The present study aimed to assess the status of successive dams on surface water quality, especially in reducing organic pollution levels, and their effects on the ecological life were investigated. Water samples were collected seasonally from three dam’s monitoring stations. Temperature, pH, dissolved oxygen, electrical conductivity, turbidity, ammonium nitrogen, nitrite nitrogen, nitrate-nitrogen, sulfate, total phosphorus, chemical oxygen demand, biochemical oxygen demand and total hardness parameters were measured in surface waters. The Geographic Information System (GIS) was used to produce thematic maps of the investigated parameters. Stations used as point feature layers were mapped using quantitative labeling via symbology. The results were compared with Turkish Regulation, 2015 and EC Directive on the quality of fresh waters needing protection or improvement to support fish life (2006) guidelines. According to the results of the analysis, Dams that are located one after the other contribute to the partial cleaning of the water by resting. Sarıyar, Gökçekaya, and Yenice Dams were built on the Sakarya River, which is one of Türkiye’s biggest and most significant river systems, for electric supply and utility of water for irrigation and fishery activities. Gökçekaya Dam Lake was built between Sarıyar Dam and Yenice Dam, which are situated in the same line of Sakarya River. Gökçekaya and Yenice Dams are fed by Sarıyar Dam Lake and do not receive fresh water. The fact that the three dams are established one after the other aids in the water’s resting and the aids in removing the suspended solids/suspended load. But, this research show that domestic, industrial, agricultural wastes carried by the branches of the rivers caused algal blooms in Dam lakes, especially which are not fed with fresh water. Due to organic pollution the decrease in dissolved oxygen, especially from time to time, negatively affects the ecological life in the lakes.
36
Slade, A. H., S. M. Anderson, and B. G. Evans. "Nitrogen fixation in the activated sludge treatment of thermomechanical pulping wastewater: effect of dissolved oxygen." Water Science and Technology 48, no. 8 (November 1, 2003): 1–8. http://dx.doi.org/10.2166/wst.2003.0446.
Анотація:
N-ViroTech, a novel technology which selects for nitrogen-fixing bacteria as the bacteria primarily responsible for carbon removal, has been developed to treat nutrient limited wastewaters to a high quality without the addition of nitrogen, and only minimal addition of phosphorus. Selection of the operating dissolved oxygen level to maximise nitrogen fixation forms a key component of the technology. Pilot scale activated sludge treatment of a thermomechanical pulping wastewater was carried out in nitrogen-fixing mode over a 15 month period. The effect of dissolved oxygen was studied at three levels: 14% (Phase 1), 5% (Phase 2) and 30% (Phase 3). The plant was operated at an organic loading of 0.7–1.1 kg BOD5/m3/d, a solids retention time of approximately 10 d, a hydraulic retention time of 1.4 d and a F:M ratio of 0.17–0.23 mg BOD5/mg VSS/d. Treatment performance was very stable over the three dissolved oxygen operating levels. The plant achieved 94–96% BOD removal, 82–87% total COD removal, 79–87% soluble COD removal, and >99% total extractives removal. The lowest organic carbon removals were observed during operation at 30% DO but were more likely to be due to phosphorus limitation than operation at high dissolved oxygen, as there was a significant decrease in phosphorus entering the plant during Phase 3. Discharge of dissolved nitrogen, ammonium and oxidised nitrogen were consistently low (1.1–1.6 mg/L DKN, 0.1–0.2 mg/L NH4+-N and 0.0 mg/L oxidised nitrogen). Discharge of dissolved phosphorus was 2.8 mg/L, 0.1 mg/L and 0.6 mg/L DRP in Phases 1, 2 and 3 respectively. It was postulated that a population of polyphosphate accumulating bacteria developed during Phase 1. Operation at low dissolved oxygen during Phase 2 appeared to promote biological phosphorus uptake which may have been affected by raising the dissolved oxygen to 30% in Phase 3. Total nitrogen and phosphorus discharge was dependent on efficient secondary clarification, and improved over the course of the study as suspended solids discharge improved. Nitrogen fixation was demonstrated throughout the study using an acetylene reduction assay. Based on nitrogen balances around the plant, there was a 55, 354 and 98% increase in nitrogen during Phases 1, 2 and 3 respectively. There was a significant decrease in phosphorus between Phases 1 and 2, and Phase 3 of the study, as well as a significant increase in nitrogen between Phases 2 and 3 which masked the effect of changing the dissolved oxygen. Operation at low dissolved oxygen appeared to confer a competitive advantage to the nitrogen-fixing bacteria.
37
Akanbi-Gada, Mariam Abiola, Amina Owoleke Veronica, AS Oluwatobi, and Oyejimi Oyeleke Abdul-Majeed. "Biomonitoring of aquatic habitat using Apodu Dam in Malete, Moro local government area of Kwara state Nigeria as a case study." Annals of Marine Science 7, no. 1 (March 21, 2023): 006–13. http://dx.doi.org/10.17352/ams.000031.
Анотація:
Water bodies such as dams are an essential part of the ecosystems and the Apodu dam, a Local Government Area of Kwara State supplies water for the populace of Malete. The water is used for both domestic and agricultural purposes. Given the proposed rural development in the catchment area of the Apodu dam, it becomes imperative therefore to do extensive biomonitoring of the dam before the development begins so as to determine the likely source of pollution in the dam as well as determine the health of the dam. Ten samples of both water and plants were collected at different sampling points designated as A-J. The samples collected were digested and analyzed using standard techniques. Data generated from the research were subjected to T-test to determine whether there is a significant variation in the two sets of data. The parameters examined fall within the permissible level of standards set by the Federal Environmental Protection Agency (FEPA) and the World Health Organisation (WHO). Total hardness (TH) was 88.00-128.80 mg/l, pH 6.60-6.80, Total dissolved solids (TDSS) 242.00-420.00 mg/l, Electrical conductivity 102.32-103.39 µs cm, Biological Oxygen Demand (BOD) 3.47-3.53 mg/l, Chemical Oxygen Demand (COD) 104.00-168.00 mg/l and Dissolved oxygen (DO) 3.47- 3.53 mg/l. The lower concentration of DO is an indication of high water quality and this is advantageous for aquatic life as it suggests that there is less decomposition of foreign materials. In conclusion, high potential for an increasingly detrimental impact on the water quality resulting from increased anthropogenic activities especially if the proposed developments commence is imminent.
38
Li, Jun Guo, Yan Shi, and Ling Hong Wei. "Influence of Dissolved Oxygen on Trivalent Chromium Removal from Wastewater by GQSS." Applied Mechanics and Materials 251 (December 2012): 416–20. http://dx.doi.org/10.4028/www.scientific.net/amm.251.416.
Анотація:
Gas quenching steel slag (GQSS) without any post treatment and modification could be utilized to remove Cr(III) from wastewater. Due to lower content of reductive material in GQSS, it was suggested that dissolved oxygen in solution should be declined slightly to the minimum with libration time, and then increased as the testing centrifuge tubes without lids because of dissolution of oxygen from atmosphere. Dissolved oxygen chromium original have significant influence on redox potential in solution. pH increased with the increasing of libration time because of dissolution of alkaline material in GQSS. But dissolution oxygen has little influence on pH in solution. It was suggested that Cr(III) removal percentage when the solution was sealed from atmosphere was slightly higher than that as the soltuion without seal, which was related with the influence of dissolved oxygen on pH and redox potential in solution.
39
Jimenez, Jose, Pusker Regmi, and Mark Miller. "Understanding Simultaneous Nutrient Removal through Low Dissolved Oxygen Operation." Proceedings of the Water Environment Federation 2018, no. 5 (January 1, 2018): 296–303. http://dx.doi.org/10.2175/193864718824940006.
40
Potter, E. C., and G. Whitehead. "Continuous removal of dissolved oxygen by established ion-exchangers." Journal of Applied Chemistry 7, no. 11 (May 4, 2007): 629–39. http://dx.doi.org/10.1002/jctb.5010071111.
41
Sarhat, Abdulmutalib Raafat, Shagul Abubaker Ali, and Muhammad Mohsin. "Assessment of Water Quality in Bawashaswar Dam/Kifri During Red Tide." IOP Conference Series: Earth and Environmental Science 1158, no. 2 (April 1, 2023): 022020. http://dx.doi.org/10.1088/1755-1315/1158/2/022020.
Анотація:
Abstract In summer 2021, water in Bawashaswar Dam turned red as a result of drought, decreasing in water supply and presence of high amount of anthropogenic pollutants. This strange situation had not happened in the region before, raising concerns among water users. In the present study, 12 samples were collected from various locations inside the reservoir. The selected physicochemical parameters include turbidity, pH, dissolved solids (TDS), electrical conductivity (EC), total hardness (TH), Magnesium (Mg+2), Calcium (Ca+2), Sulfate (SO4 -2), dissolved oxygen (DO), biological oxygen demand (BOD), Iron (Fe+2) and Fluoride (F-) were analyzed and were also used to determine water quality index (WQI). The results were obtained on the weighted arithmetic index (WAI) method. So, the parameters of water quality were found to be very high exceeding the limit range. This indicated that water in the reservoir has poor water quality and cannot be used either for drinking, irrigation, and fish culture.
42
Patience, Machiva. "AN ASSESSMENT OF PHYSICOCHEMICAL AND MICROBIOLOGICAL CHARACTERISTICS OF WATER IN INSUKAMINI CATCHMENT WATER SOURCES AND THE SUITABILITY OF WATER FOR DOMESTIC USE." Gujarat Journal of Extension Education 33, no. 1 (June 25, 2022): 12–15. http://dx.doi.org/10.56572/gjoee.2022.33.1.0003.
Анотація:
Insukamini catchment depends on hand dug wells, sand water abstraction, dam, and borehole water sources for their domestic uses. On hand dug wells and sand water abstraction, people rely on natural filtration of bacteria and consider the water as safe, however the location and management of some of these water sources raise suspicion of possible contamination. The aim of this study was to assess drinking water quality in terms of selected physico-chemical and microbiological parameters, and people's perceptions on aesthetic parameters. Water samples were collected from five water sources, namely sand water abstraction, dam, hand dug well, borehole and municipal water. Three samples were collected from each water source to make 63 samples. Temperature, pH, electrical conductivity, and dissolved oxygen measured using HI 9143 dissolved oxygen meter, YSI pH 100, HI 9143 dissolved oxygen meter and HI 8633 conductivity meter respectively. On laboratory experiments total suspended solids measured using filter disk, total dissolved solids using gravimetric method (SA, 2008), total and feacal coliform were measured using spread plate method. All water sources had total coliform levels above the WHO standards for drinking water of 1000mg/L. For E. coli, borehole and municipal water sources complied with the WHO standard with the means of zero cfu/ 100ml. Low pH mean of 5.001 was found in borehole water and the other water sources were within the accepted range of 6.5 to 8.5. Municipal and dam point (A) water sources had highest levels of TDS, borehole, and dam point (C) had TSS levels above maximums allowable of 1000mg/L and 150mg/L respectively. Temperature, DO and EC of all water sources were within the WHO standards. Overall, all water sources were not complying with WHO standard for drinking water. People described municipal water source as best for drinking purpose, dam, sand water abstraction and hand dug well water sources described as soft and good for laundry and bathing as compared to borehole which was described as hard. The results indicated that water from the sources under study were not suitable for drinking purposes without treatment. The water should rather be used for other domestic uses such as laundry and bathing. However, municipal water should be boiled or use water purification tablets (chlorine tablets) before drinking. An integrated approach is therefore required to minimize and avoid water pollution within the catchment.
43
Sturm, B. S. McSwain, and R. L. Irvine. "Dissolved oxygen as a key parameter to aerobic granule formation." Water Science and Technology 58, no. 4 (September 1, 2008): 781–87. http://dx.doi.org/10.2166/wst.2008.393.
Анотація:
Much research has asserted that high shear forces are necessary for the formation of aerobic granular sludge in Sequencing Batch Reactors (SBRs). In order to distinguish the role of shear and dissolved oxygen on granule formation, two separate experiments were conducted with three bench-scale SBRs. In the first experiment, an SBR was operated with five sequentially decreasing superficial upflow gas velocities ranging from 1.2 to 0.4 cm s−1. When less than 1 cm s−1 shear was applied to the reactor, aerobic granules disintegrated into flocs, with corresponding increases in SVI and effluent suspended solids. However, the dissolved oxygen also decreased from 8 mg L−1 to 5 mg L−1, affecting the Feast/Famine regime in the SBR and the substrate removal kinetics. A second experiment operated two SBRs with an identical shear force of 1.2 cm s−1, but two dissolved oxygen concentrations. Even when supplied a high shear force, aerobic granules could not form at a dissolved oxygen less than 5 mg L−1, with a Static Fill. These results indicate that the substrate removal kinetics and dissolved oxygen are more significant to granule formation than shear force.
44
Cheng, Qingfeng. "Competitive mechanism of ammonia, iron and manganese for dissolved oxygen using pilot-scale biofilter at different dissolved oxygen concentrations." Water Supply 16, no. 3 (December 29, 2015): 766–74. http://dx.doi.org/10.2166/ws.2015.190.
Анотація:
In this study, the competitive mechanism of ammonia, iron and manganese for dissolved oxygen (DO) in a biofilter was investigated, and a new start-up method of a biofilter for ammonia, iron and manganese removal was approved, which can effectively shorten the start-up period from 3–4 months to 51 days. The results demonstrated that when DO was sufficient (about 8 mg · L−1), ammonia, iron and manganese could be completely removed. When DO decreased from 6.5 to 4 mg · L−1, the concentration of ammonia in the effluent increased accordingly, though iron and manganese were removed efficiently. When DO was as low as 3 mg · L−1, only iron was removed, whereas most of the ammonia and manganese still existed in the effluent. In addition, the oxidizing rates of the pollutants were not affected significantly with DO decrease. Turbidity removal in the biofilter was also investigated, and the results demonstrated that the turbidity decreased to less than 0.5 NTU at 0.4 m depth of the filter.
45
Gogina, Elena, and Igor Gulshin. "Characteristics of Low-Oxygen Oxidation Ditch with Improved Nitrogen Removal." Water 13, no. 24 (December 15, 2021): 3603. http://dx.doi.org/10.3390/w13243603.
Анотація:
This article presents a study on the operational stability of laboratory oxidation ditches, designated for synthetic and real wastewater and operable at low concentrations of dissolved oxygen. The project encompassed the stability monitoring of activated sludge depending on sedimentation characteristics and hydrobiological indicator microorganisms, determining (1) the size of sludge floccules and (2) the main functional groups of microorganisms identified in the course of the PCR analysis and reaction rates, plotted using the Michaelis–Menten enzymatic kinetics for the mixed culture biomass. The most stable system involves a bioreactor featuring dissolved oxygen gradients that range from 1.9 to 0.15 mg/L s, a specific organic load of 0.21 gBOD/g/d and a hydraulic retention time of 12 h. A built-in settling tank allows the consideration of the potential generation of large floccules of activated sludge in oxidation ditches (at least 300 μm) that increase the efficiency of simultaneous nitrification and denitrification. Thus, the obtained reaction rates can be used in calculations and simulations of the operation of oxidation ditches at low concentrations of dissolved oxygen.
46
Zhou, Jia Fei, Cong Feng Wang, De Fu Liu, Jing Wen Xiang, Ping Zhao, and Fang Lu Kou. "Hydrology and Water Quality Survey Near the Gezhouba Dam in the Winter." Advanced Materials Research 726-731 (August 2013): 3256–61. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3256.
Анотація:
Filed hydrology and water quality data were collected near the Gezhouba Dam early December of 2012 to analyze the response of Chinese Sturgeon survival condition to water temperature, dissolved oxygen (DO), pH, transparency (SD) and bottom flow-velocity. The results showed that water temperature lag is unconspicuous. The water temperature of Gezhouba Dam Sanjiang (GDS) was lower than that of Gezhouba Dam River (GDR), and it hindered propagation of sturgeon eggs. DO decreased fast in the vertical water column of GDS, pH ranged from 7.5 to 7.71. The hydrology and water quality were suitable for the life condition of sturgeon eggs and fry, except index of bottom flow-velocity.
47
Bahroun, Sofia, and Warda Chaib. "The quality of surface waters of the dam reservoir Mexa, Northeast of Algeria." Journal of Water and Land Development 34, no. 1 (September 26, 2017): 11–19. http://dx.doi.org/10.1515/jwld-2017-0034.
Анотація:
Abstract In this work, we have conducted a physicochemical study that assesses the impact of agricultural activities and urban domestic wastewater on the surface water quality of the dam reservoir Mexa in the area of El-Taref, which is located in the eastern coastal basin of Constantine. 36 samplings have been conducted for three years (2010, 2011 and 2012), at the rate of one sampling per month on the dam reservoir water; 36 samples have been analysed. The samples taken have been subjected to an in situ measurement of physicochemical parameters (temperature, hydrogen potential, electric conductivity and dissolved oxygen) and laboratory analysis (anions, cations, biological oxygen demand, chemical oxygen demand, organic matter, phosphate, nitrate, nitrite and ammonium). Concentrations of various organic and inorganic pollutants varied from one month to another and from one year to another. From a temporal point of view, the contamination of water of the dam reservoir Mexa varies according to climatic conditions, being generally low during the winter period and high during the low-flow periods. The results obtained reveal that water of the dam reservoir Mexa is fairly contaminated. It is certain that the dam reservoir is subject to pollution of agricultural and urban origin.
48
Schumacher, G., and I. Sekoulov. "Polishing of secondary effluent by an algal biofilm process." Water Science and Technology 46, no. 8 (October 1, 2002): 83–90. http://dx.doi.org/10.2166/wst.2002.0150.
Анотація:
The potential in polishing secondary effluent by an algal biofilm composed of different green and bluegreen algae was investigated. During the photosynthesis process of algal biofilm oxygen was produced while dissolved carbon dioxide was consumed. This led to an increasing pH due to the change of the carbon dioxide equilibrium in water. The high pH caused precipitation of dissolved phosphates. The attached algae took up nitrogen and phosphorus during the growth of biomass. In addition to nutrient removal, an extensive removal of faecal bacteria was observed probably caused by adsorption of the algal biofilm and by photo-oxidation involving dissolved oxygen. The experimental results suggest that a low-cost, close to nature process especially for small wastewater treatment plants for nutrient removal and bacteria reduction can be developed with the aid of an algal biofilm.
49
Bovendeur, J., F. Spuij, P. G. B. Hermans, and A. Klapwijk. "Mechanisms and Kinetics of COD Removal and Simultaneous Oxygen Consumption in a Rotating Biological Contactor Biofilm." Water Science and Technology 22, no. 1-2 (January 1, 1990): 75–87. http://dx.doi.org/10.2166/wst.1990.0137.
Анотація:
A study on aerobic biofilm COD removal and simultaneous respiration is made using a Wazu respirationmeter unit. In a closed recirculating system completely submerged RBC biofilm samples have been examined in short-term batch experiments, using the corresponding waste water or dissolved acetate. The removal of dissolved organic substrate and the respiration were found to answer the ½-order/0-order kinetic model, whereas the removal of suspended solids COD (CODs) showed 1-order kinetics. Under conditions usually met in practice the 0-order rates for dissolved COD(CODd) removal and respiration were 30–40 gm−2d−1 and 10–16 gm−2d−1, respectively; in absence of organic substrate a certain background respiration was observed (3.5–9.0 gm−2d−1). As a result of the 1-order kinetics over a wide concentration range, extremely high CODs removal rates were observed even exceeding 300 gm−2d−1. The difference between the maximum respiration and the CODs removal rates is attributed to physical biofilm adsorption processes. Biofilm COD removal kinetics for waste water containing both CODs and CODd are discussed, illustrating that the kinetic order of the combined process and the reaction constant strongly depends on the CODs/CODd ratio. Conclusion is that a RBC biofilm loaded with a CODs/CODd mixture oxidizes some dissolved organic matter and acts as a catalyst in the coagulation and flocculation of fine suspended solids.
50
Tepe, Rıdvan, and Banu Kutlu. "Karkamış Baraj Gölü (Gaziantep) Su Kalitesinin İncelenmesi." Turkish Journal of Agriculture - Food Science and Technology 7, no. 3 (March 12, 2019): 458. http://dx.doi.org/10.24925/turjaf.v7i3.458-466.2409.
Анотація:
This study was conducted in order to reveal the physico-chemical properties of the Karkamis Dam Lake located within the boundaries of Sanliurfa and Gaziantep, water samples were taken from 5 stations at 4 and 8 m depths between January and December 2015. Temperature, pH, dissolved oxygen, electrical conductivity, ammonium nitrogen, nitrate nitrogen, ortho phosphate, phosphorus, total nitrogen and total phosphorus values of water were measured during the year. The detected values were found as temperature (14.3-21.6°C average: 9.4), pH (8.4-9.1-7.8), dissolved oxygen (9-10-11.8 mg L-1), electrical conductivity (251-332-412 ,00S cm-1) ammonium nitrogen (0,003-0,069-0,194 mg L-1), nitrate nitrogen (1,549-2,292-3,473 mg N L-1), nitrite nitrogen (0.001-0.006-0.053 mg L-1), ortho phosphate phosphorus (0.007-0.034-0.076 mg L-1), total nitrogen (0.722-1.1514-1.696 mg L-1), total phosphorus (0.007-0.016-0.026 mg L-1). The Karkamis Dam Lake has a Class I high quality water class according to the Quality Criteria for Inland Water Resources Classification according to the Surface Water Quality Management Regulation.