Wastewater Stabilization Ponds Research Articles

Wastewater pond systems using chemical precipitation (fellings dams): state of the art in Sweden.

Chemical precipitation in wastewater stabilization ponds - in Scandinavia called fellings dams - has been in operation for more than 50 years. Slaked lime and aluminium salts are the most common chemicals used for precipitation. Long and narrow forms of the ponds and a detention time of at least 5 days have shown, even at a low water temperature and below an ice cover, to produce an average effluent quality of 70 mg CODCr/l, 0.2 mg Tot-P/l, 20 mg Tot-N/l (CODCr: chemical oxygen demand; Tot-P: total phosphorus; Tot-N: total nitrogen) and low levels of pathogenic bacteria. The systems use low amounts of energy and no wastewater is by-passed at the plants. Fellings dams have recently been tried to support overloaded wastewater collection systems.

Pilot-scale evaluation of semi-passive treatment technologies for the treatment of septage under temperate climate conditions

Population growth in rural Canada has resulted in an increase in municipal septage generation, which could overload existing treatment facilities that rely on biological treatment approaches. To address concerns associated with potential shock loading of these systems, three semi-passive wastewater treatment technologies were compared at the pilot-scale to identify a suitable approach to augment the capacity of an existing wastewater stabilization pond facility in rural Ontario. Two of these technologies, the BioDome and BioCord systems, were commercially available systems that make use of biofilm technology to improve treatment performance and enhance the robustness to temperature and hydraulic loading fluctuations. The third approach involved the use of the natural filtration capacity of zebra mussels to improve effluent quality. The three technologies were assessed against a control for reductions in regulated wastewater parameters with an emphasis on nutrient (ammonia/ammonium, orthophosphate) reductions, air cycling, energy consumption, and performance following exposure to anoxic conditions. The BioCord system was the only technology that was found to significantly outperform the control, exhibiting reductions of 69%, 47%, 77% and 81% for NH3/NH4+, TN, COD and TSS, respectively. The BioCord system also had the lowest maintenance and energy requirements, likely due to its design, which provided the biofilm with optimal oxygen and substrate contact. Consequently, the BioCord system could develop a more stable, heterogeneous microbial population and maintain high levels of activity in its biofilm, even during periods of extended anaerobic conditions. This also suggested that the BioCord system would require less aeration, and hence a lower energy expenditure, than the other systems. Furthermore, the BioCord system showed the fastest rates of recovery, reaching significant levels of parameter reductions within one week of system re-initiation.

The use of wastewater in livestock production and its socioeconomic and welfare implications.

Although epidemiological studies have found a significant amount of toxins in surface water, a complex link between animals' access to wastewater and associated animal and human welfare losses needs to be explored. The scarcity of safe water has put stress on the utilization of wastewater for crops and livestock production. The access of animals to wastewater is related to the emergence of dangerous animal's diseases, hampering productivity, increasing economic losses, and risking human health along the food chain. This review explores use of wastewater for agriculture, epidemiological evidence of microbial contamination in wastewater, and animal and human welfare disruption due to the use of wastewater for crop and livestock production. More specifically, the review delves into animals exposure to wastewater for bathing, drinking, or grazing on a pasture irrigated with contaminated water and related animal and human welfare losses. We included some scientific articles and reviews published from 1970 to 2017 to support our rational discussions. The selected articles dealt exclusively with animals direct access to wastewater via bathing and indirect access via grazing on pasture irrigated with contaminated wastewater and their implication for animal and human welfare losses. The study also identified that some policy options such as wastewater treatments, constructing wastewater stabilization ponds, controlling animal access to wastewater, and dissemination of necessary information to ultimate consumers related to the source of agricultural produce and wastewater use in animal and crop production are required to protect the human and animal health and welfare.

Disinfection and removal of human pathogenic bacteria in arctic waste stabilization ponds.

Wastewater stabilization ponds (WSPs) are commonly used to treat municipal wastewater in Arctic Canada. The biological treatment in the WSPs is strongly influenced by climatic conditions. Currently, there is limited information about the removal of fecal and pathogenic bacteria during the short cool summer treatment season. With relevance to public health, the objectives of this paper were to determine if treatment in arctic WSPs resulted in the disinfection (i.e., removal of fecal indicator bacteria, Escherichia coli) and removal of selected human bacterial pathogens from the treated effluent. The treatment performance, with focus on microbial removal, was assessed for the one-cell WSP in Pond Inlet (Nunavut [NU]) and two-cell WSP in Clyde River (NU) over three consecutive (2012-2014) summer treatment seasons (late June-early September). The WSPs provided a primary disinfection treatment of the wastewater with a 2-3Log removal of generic indicator E. coli. The bacterial pathogens Salmonella spp., pathogenic E. coli, and Listeria monocytogenes, but not Campylobacter spp. and Helicobacter pylori, were detected in the untreated and treated wastewater, indicating that human pathogens were not reliably removed. Seasonal and annual variations in temperature significantly (p<0.05) affected the disinfection efficiency. Improved disinfection and pathogen removal was observed for the two-cell system in Clyde River as compared to the one-cell system in Pond Inlet. A quantitative microbial risk assessment should be performed to determine if the release of low levels of human pathogens into the arctic environment poses a human health risk.

Selecting wastewater sites using analytical hierarchy and geographic information system

Locating sewer networks and treatment facilities for processing prior to disposal of domestic and industrial wastewater is a complex, difficult, tedious and protracted process requiring evaluation of many different criteria. To find the best place to locate a wastewater stabilisation pond in Behbahan, a city in Iran, ecological, technical and economical criteria were taken into consideration. Each of these criteria had some subcriteria. The analytical hierarchy process is a useful tool used for decision-making problems. In this paper, a geographical information system and the analytical hierarchy process as a multi-criteria decision-making tool were integrated for site selection of wastewater stabilisation ponds. The importance of each criterion was determined by expert survey. After identification and weighting each criterion using the analytical hierarchy process, the information layers were entered onto a geographic information system. Finally, all the weighted maps were reclassified to select the appropriate site for waste stabilisation ponds for the city.

Sludge distribution and annual accumulation rate in wastewater stabilization ponds in Northern Greece regions

Sludge distribution and annual accumulation rate in wastewater stabilization ponds in Northern Greece regions

Nitrogen removal kinetics in wastewater stabilization pond systems in Greece

Nitrogen removal kinetics in wastewater stabilization pond systems in Greece

Enrichment of 15N/14N in wastewater-derived effluent varies with operational performance of treatment systems: implications for isotope monitoring in receiving environments.

Stable nitrogen isotope ratios are routinely used to trace the dispersion and assimilation of wastewater-derived N in receiving environments, but few isotope studies have investigated wastewater treatment plants and ponds themselves. An improved understanding of N isotope compositions in effluent will help assess treatment plant processes and performance and will help trace sources of excess nutrients in receiving environments. Here, we assess N budgets and treatment processes in seven wastewater treatment plants and wastewater stabilisation ponds in northern Australia based on concentrations and isotope ratios of N in effluent. We show that δ15N values in effluent are linked to treatment type, effectiveness of conversion of ammonia and levels of gaseous N emissions. These relationships suggest that N isotope monitoring of wastewater treatment plants and ponds can provide an integrated assessment of treatment performance and gaseous N emissions on a pond- or plant-wide scale that is not readily available through other methods. Our findings further imply that monitoring N isotope ratios in receiving environments cannot be assumed to be universally effective as their sensitivity to uptake of wastewater-derived N will vary with the characteristics of individual treatment systems. Paradoxically, N isotope monitoring is less effective where treatment systems are functioning poorly and where monitoring needs are the greatest.

Environmental and operational factors affecting carbon removal in model arctic waste stabilization ponds

Wastewater Stabilization Ponds (WSPs) are passive treatment systems influenced by both the ambient environment and the manner in which they are operated. Construction of wastewater treatment facilities is particularly challenging in the Canadian Arctic because of the remoteness of the communities and the extreme climate. Here, experimental bench scale WSPs were used to simulate single cell WSPs operating under summer treatment conditions in the Arctic. Experiments were performed to examine factors (temperature, irradiance, initial carbon concentrations, and organic loading rate) that may influence the oxygen state and carbon removal. All four factors were found to significantly (p<0.05) affect oxygen state and carbon removal, but temperature (5°C vs 15°C) and initial carbon concentration (80 vs 240mg/l) were found to be the most important factors. Final CBOD5 concentrations in the experimental columns ranged from <10 to 150mg/l, and only experimental columns operated at low temperature and high initial carbon concentrations had final CBOD5 concentrations >30mg/l. Phytoplankton growth and metabolism appears to have a prominent impact on CBOD5 removal and the oxygen status of the experimental WSPs. The findings suggest that WSPs operating in cool arctic climates are more sensitive to perturbation by weather or operational changes than similar systems in warmer climates, and greater consideration for process resiliency needs to be incorporated into the design of arctic WSPs. This study provides further evidence that WSPs are an appropriate municipal wastewater technology for the Arctic and can achieve effluent CBOD5 concentrations that meet secondary wastewater treatment standards, provided they are appropriately sized, designed, and operated for arctic conditions.

Phosphorus Removal Mechanisms in a Facultative Wastewater Stabilization Pond

The objective of the study is to improve understanding of natural phosphorus removal processes to limit the need for chemical addition in an existing facultative wastewater stabilization pond in Manitoba, Canada. Surface samples were collected from lagoon cells and analyzed. The windward and leeward sides of the ponds were sampled and the results were averaged. Phosphorus appears to be removed by assimilation into biomass; and precipitation at alkaline pH. When the nitrogen to phosphorus (N/P) ratio and ideal theoretical N/P ratio for cellular growth are compared, there appears to be nitrogen-limiting conditions in the secondary cells of the stabilization system. There is evidence ammonia removal by free ammonia volatilizing to the atmosphere may be contributing to nitrogen-limiting conditions in the secondary lagoon cells. Additional nitrogen may need to be supplied to remove more phosphorus by assimilation into biomass.

Geotextile biofiltration of primary treated municipal wastewater under simulated arctic summer conditions

Wastewater stabilization ponds (WSPs) are common for wastewater treatment in remote Canadian Arctic communities. In this paper, two geotextiles of different mass/unit areas are examined as a potential biofiltration upgrade to existing WSPs in arctic summer conditions. The intended role of the geotextile is to provide additional treatment of municipal wastewater seeping from these WSPs. Column filtration experiments were performed using municipal wastewater in a controlled laboratory environment at either 10 °C or 2 °C. The columns contained one of two different nonwoven geotextiles over 10 cm of gravel, simulating a WSP berm in contact with exfiltrating wastewater. Weekly wastewater samples were taken upstream and downstream of the geotextile/gravel filter and were analyzed for a suite of water quality parameters; the hydraulic conductivity of the columns was also measured weekly. Results showed that it is possible to accumulate biomass on geotextile material over a 3 month period at these temperatures, which corresponded with 1–2 log reductions in hydraulic conductivity. Significant removal of total suspended solids, 5-day biochemical oxygen demand, total nitrogen, and total phosphorus was observed; however, removal efficiencies for most parameters were reduced at the lower temperature. This study demonstrates that geotextiles could be used to enhance the performance of WSP systems operating in arctic climates.

Assessing the suitability of sediment-type bioelectrochemical systems for organic matter removal from municipal wastewater: a column study.

This study examines the use of bioelectrochemical systems (BES) as an alternative to rock filters for polishing wastewater stabilisation ponds (WSPs) effluent, which often contains soluble chemical oxygen demand (SCOD) and suspended solids mainly as algal biomass. A filter type sediment BES configuration with graphite granules (as the surrogate for rocks in a rock filter) was examined. Three reactor columns were set up to examine three different treatments: (i) open-circuit without current generation; (ii) close-circuit - with current generation; and (iii) control reactor without electrode material. All columns were continuously operated for 170 days with real municipal wastewater at a hydraulic retention time of 5 days. Compared to the control reactor, the two experimental reactors showed significant improvement of SCOD removal (from approximately 25% to 66%) possibly due to retention of biomass on the graphite media. However, substantial amount of SCOD (60%) was removed via non-current generation pathways, and a very low Coulombic efficiency (6%) was recorded due to a poor cathodic oxygen reduction kinetics and a large electrode spacing. Addressing these challenges are imperative to further develop BES technology for WSP effluent treatment.

The survey of biological absorption of hexavalent chromium from aqueous solutions by Wastewater stabilization pond algae

The survey of biological absorption of hexavalent chromium from aqueous solutions by Wastewater stabilization pond algae

Multivariate statistical analysis of water chemistry conditions in three wastewater stabilization ponds with algae blooms and pH fluctuations

The wastewater stabilization ponds (WSPs) at a wastewater treatment facility in eastern Ontario, Canada, have experienced excessive algae growth and high pH levels in the summer months. A full range of parameters were sampled from the system and the chemical dynamics in the three WSPs were assessed through multivariate statistical analysis. The study presents a novel approach for exploratory analysis of a comprehensive water chemistry dataset, incorporating principal components analysis (PCA) and principal components (PC) and partial least squares (PLS) regressions. The analyses showed strong correlations between chl-a and sunlight, temperature, organic matter, and nutrients, and weak and negative correlations between chl-a and pH and chl-a and DO. PCA reduced the data from 19 to 8 variables, with a good fit to the original data matrix (similarity measure of 0.73). Multivariate regressions to model system pH in terms of these key parameters were performed on the reduced variable set and the PCs generated, for which strong fits (R2 > 0.79 with all data) were observed. The methodologies presented in this study are applicable to a wide range of natural and engineered systems where a large number of water chemistry parameters are monitored resulting in the generation of large data sets.

Occurrence patterns of pharmaceutical residues in wastewater, surface water and groundwater of Nairobi and Kisumu city, Kenya

Emerging organic contaminants have not received a lot of attention in developing countries, particularly Africa, although problems regarding water quantity and quality are often even more severe than in more developed regions. This study presents general water quality parameters as well as unique data on concentrations and loads of 24 pharmaceuticals including antibiotic, anti(retro)viral, analgesic, anti-inflammatory and psychiatric drugs in three wastewater treatment plants, three rivers and three groundwater wells in Nairobi and Kisumu. This allowed studying removal efficiencies in wastewater treatment, identifying important sources of pharmaceutical pollution and distinguishing dilution effects from natural attenuation in rivers. In general, antiretrovirals and antibiotics, being important in the treatment of common African diseases such as HIV and malaria, were in all matrices more prevalent as compared to the Western world. Wastewater stabilization ponds removed pharmaceuticals with an efficiency between 11 and 99%. Despite this large range, a different removal is observed for a number of compounds, as compared to more conventional activated sludge systems. Total concentrations in river water (up to 320 μg L−1) were similar or exceeded concentrations in untreated wastewater, with domestic discharges from slums, wastewater treatment plant effluent and waste dumpsites identified as important sources. In shallow wells situated next to pit latrines and used for drinking water, the recalcitrant antiretroviral nevirapine was measured at concentrations as high as 1–2 μg L−1. Overall, distinct pharmaceutical contamination patterns as compared to the Western world can be concluded, which might be a trigger for further research in developing regions.

Time series relationships between chlorophyll-a, dissolved oxygen, and pH in three facultative wastewater stabilization ponds

This study involved the evaluation of time-series relationships between chlorophyll-a (chl-a), dissolved oxygen (DO), and pH in three facultative wastewater stabilization ponds (WSPs) operated in series at a wastewater treatment plant in eastern Ontario, Canada.

Effects of Environmental Factors on the Disinfection Performance of a Wastewater Stabilization Pond Operated in a Temperate Climate

Treatment in a wastewater stabilization pond (WSP) relies on natural purification processes, which can be sensitive to both location and climate. This study investigated the effects of three environmental factors, pH, dissolved oxygen (DO) and temperature, on disinfection efficiency in a WSP system consisting of three facultative cells, and operated in a temperate climate region, in Eastern Ontario, Canada. Indicator organism (Escherichia coli (E. coli)) removal in WSP systems is driven by a combination of different factors. Elevated pH and DO concentrations, which are attributed to the presence of algae, are important factors for effective disinfection. Therefore, the presence of algae in natural wastewater treatment systems can contribute appreciably to disinfection. Consequently, based on algal concentrations, removal efficiencies of pathogenic microorganisms during wastewater treatment over the course of a year can be highly variable, where higher removal efficiencies would be expected in summer and fall seasons.

Modelling antibiotics transport in a waste stabilization pond system in Tanzania

Antibiotics in wastewater have become a growing problem in urban and peri-urban areas in developing countries as a result of increased use and misuse of antibiotics. A simple dynamic model, that describes the most important removal processes of antibiotic from the wastewater stabilization pond system (WSP) “Mafisa” in Morogoro, Tanzania, was developed using STELLA® software package. The model was based on liquid chromatography tandem mass spectrometry (LCMS/MS) analysis of trimethoprim, in water collected in the WSP. Concentrations of trimethoprim measured in the dry season and the rainy season were used in development of the model. To determine the model's applicability to simulate the removal of trimethoprim, a calibration was performed using concentrations from the dry season and a validation was performed using concentrations from the rainy season. To test the model's capacity to simulate the removal of other antibiotics than trimethoprim, a second validation was performed for three other antibiotics; metronidazole, sulfamethoxazole and ciprofloxacin. A two-tailed t-test with a confidence interval of 95% showed no significant difference (P=0.7819) between the values given by the model (CSIM) and the values measured by LCMS/MS (COBS) of the first validation, and the standard deviation (SD) between the differences was 1%. The second validation gave a mean SD=18% (found by a two-tailed t-test with a confidence interval of 95%) of the differences between CSIM and COBS. The model was developed under the assumption that settling, biodegradation, hydrolysis and photolysis were the only removal processes other than outlet. The major removal processes for trimethoprim and sulfamethoxazole were through settling and the outlet. Ciprofloxacin was removed by settling in the first pond. Metronidazole was mainly removed through the outlet, but settling and hydrolysis/photolysis also played a role. A sensitivity analysis (±10%) showed that the soil adsorption coefficient, the amount of suspended matter and the ratio of flow rate and volume were the most sensitive parameters. To strengthen the model, the exact removal processes should be further analysed. To apply the model on other WSP, a calibration of the settling rate constant and the amount of suspended matter should be performed.

Determination of Algae and Macrophyte Species Distribution in Three Wastewater Stabilization Ponds Using Metagenomics Analysis

This study involved the evaluation of algae and macrophyte species distributions in three wastewater stabilization ponds (WSPs) at a wastewater treatment plant in Ontario, Canada, which has experienced high pH levels at the final effluent and excessive algae growth during the summer since 2003. From samples collected from the system, the relative abundances of specific algae and aquatic plant (macrophyte) taxa were assessed and correlated to water chemistry data. A strong shift from the dominance of green algae, chlorophyceae, in WSP#2, to the dominance of aquatic macrophytes, embryophyta, in WSP#4, was observed and corresponded to field observations. Correlation of the abundances to nutrient parameters suggested that the macronutrient rich conditions in WSP#2 allowed floating green algae to proliferate against macrophytes. In WSP#1 and WSP#4, macrophytes competed against algae and thrived, due to their adaptability to lower nutrient conditions. The pH increases occurred primarily in WSP#2 and were not buffered or reduced in WSP#1 and WSP#4. Two alternatives strategies for pH control were recommended for the system: decreasing algae growth in WSP#2 through duckweed seeding or macronutrient loading reduction; or designing and implementing a constructed wetland (CW) in WSP#4 with soil and vegetation to buffer pH prior to release.

Survey of Waste water Stabilization Pond Potential in Meeting Environmental Standards

Introduction: Industrial development and urban sprawl, has led to the production of huge volumes of wastewater. Wastewater is harmful to human and has adverse effects on natural environment. With regard to importance of human health and protecting sources from pollution, this study was carried out to evaluate the wastewater stabilization pond performance, Olang treat ment plant, Mashhad. Results:The characteristic of inputting raw wastewater introduces the wastewater as a much polluted one. The ratio at input channel was 0.56. The average concentration of BOD5, COD and TSS in effluent was 75±30.67, 145±19.46 and 86±13.28 mg/ L respectively in the first year and 83±14.0, 146±23.7and 109±14.7mg/ L respectively in the second year. The treatment plant efficiency for these parameters was 79.7±10.7, 82.5±4.5and 77.1±3.9% for the first and 82.7±5.11, 82.82±3.82 and 78.46±3.93% for the second period. Conclusion: The effluent can be used for agriculture irrigation because its characteristics are accordance with the standards of Iranian Depart ment of Environ ment.