Waste Stabilization Pond System Research Articles

Assessing oxidation pond design criteria in a tropical town with low water availability

The waste stabilization pond system of Brazlandia consists of two series of anaerobic and facultative ponds running in parallel. Due to the low water availability in the region and the growth of the population, the design conditions of hydraulic retention time and organic loading were strongly modified during the operational period. Assessing of nine years of operational data in comparison with the current design approaches showed that this situation has affected the anaerobic pond efficiency. However, despite what is found in the literature, the increase of anaerobic pond water temperature beyond 20°C was accompanied by decrease in COD removal efficiency. The longer retention times observed in the facultative ponds have favored the increase of algae concentration in the pond, which reduced the overall COD removal efficiency. However, when the filtered sample is taken into consideration, the values easily fit the empirical models proposed in the literature. No significant correlation was obtained between the complete mixing flow model and operational data, which suggests that the reaction constant K is not so constant. In addition to dependence on temperature, Kfilt. values showed a statistically significant correlation with applied COD load.

The efficiency of a combined waste stabilisation pond/maturation pond system to sanitise waste water intended for recreational re-use

Concern was expressed about the microbiological quality of irrigation water obtained from a combined sewage treatment facility. Treated effluent from the system is used to irrigate sports fields and public parks. This system primarily serves a community with well developed sanitation and also receives partially stabilised waste water from a neighbouring community with limited sanitation. Special concern was expressed for quality of irrigation water when certain stages of the system would be used as waste stabilisation pond system (WSP) during possible prolonged periods of main system failure. During such periods raw sewage would be discharged into such WSP from which irrigation water would still be withdrawn regularly. The pathogen removal efficiency of various parts of the total system including original WSP used within the system, was investigated. Faecal coliforms, male specific coliphages and presence of helminth eggs were used to indicate removal efficiency. Results proved that water from the activated sludge unit was sufficiently sanitised by tertiary treatment ponds (the original WSP). Indications are that the original WSP system was not as efficient in removing pathogens from irrigation water when used as emergency standby WSP.

Occurrence and removal of Giardia sp. cysts by Kenyan and French waste stabilisation pond systems

A study was conducted to determine the occurrence and removal of Giardia sp. cysts in municipal wastewater by two waste stabilisation pond systems; one at Eldoret, Kenya and one at Meze, France. A total of 71 and 26 grab raw wastewater samples from Eldoret and Meze, respectively, were examined for the presence of cysts. Cysts were detected in 37% (26) and 100% (26) raw wastewater samples, respectively. Cyst concentrations detected to raw wastewater samples ranged from 1 x 103 to 2.5 x 104 cysts/l at Eldoret and 230 to 2.5 x 104 cysts/l at Meze. At Eldoret, all anaerobic (8/8), secondary facultative (5/5) and primary maturation (5/5) pond effluent samples examined were positive for Giardia. Cyst concentrations ranged from 1.25 to 483 cysts/l (anaerobic), 23.5 to 192.5 cysts/l (secondary facultative) and 17.2 to 118.5 cysts/l (primary maturation), respectively. At Meze, cysts were detected in 12 of 12 primary facultative (range 4.4 to 48 cysts/l) and 9 of 11 (82%) primary maturation pond effluents (range 0.2 to 16 cysts/l). In final maturation pond effluent, Giardia cysts were detected in 100% of final pond effluents discharged from Eldoret (n=10; range 21 to 90 cysts/l) and 7 of 16 (44%; range 0.1 to 2.5 cysts/l) from Meze. The occurrence of cysts in final pond effluents examined would indicate that cumulative retention periods of up to 25.3 days at Eldoret and 40 days at Meze would be sufficient to remove between 99.1% and 99.7% of cysts, respectively, but that such retention periods are insufficient to ensure the complete removal of Giardia sp. cysts.

Assessing oxidation pond design criteria in a tropical town with low water availability

The waste stabilization pond system of Brazlandia consists of two series of anaerobic and facultative ponds running to parallel. Due to the low water availability in the region and the growth of the population, the design conditions of hydraulic retention time and organic loading were strongly modified during the operational period. Assessing of nine years of operational data in comparison with the current design approaches showed that this situation has affected the anaerobic pond efficiency. However, despite what is found in the literature, the increase of anaerobic pond water temperature beyond 20°C was accompanied by decrease in COD removal efficiency. The longer retention times observed to the facultative ponds have favored the increase of algae concentration in the pond, which reduced the overall COD removal efficiency. However, when the filtered sample is taken into consideration, the values easily fit the empirical models proposed in the literature. No significant correlation was obtained between the complete mixing flow model and operational data, which suggests that the reaction constant K is not so constant. In addition to dependence on temperature, Kfilt values showed a statistically significant correlation with applied COD load.

The performance of an innovative tropical experimental waste stabilisation pond system operating at high organic loadings

In this study on the experimental pond complex at the Federal University of Paraiba in NE Brazil the organic loadings were were more than doubled to investigate the effect on pond performance. The results emphasise the tolerance of the pond system at high loadings without odour production or significant loss of efficiency in terms of BOD removal and bacterial pathogen removal, although nutrient removal by the maturation ponds was reduced. At high organic loadings baffled maturation ponds were more efficient at faecal coliform removal (FC). A minimum of 3 ponds in series are required to ensure maximum BOD removal. Shallow maturation ponds were also more efficient at FC removal although the depth of the facultative ponds had limited effect on BOD removal efficiency.

Performance of the phase II Dandora Waste Stabilisation ponds the largest in Africa: The case for anaerobic ponds

This paper describes the performance of the Dandora Waste Stabilisation Pond System which treats the industrial and domestic sewage from the City of Nairobi, Kenya and is the largest pond system in Africa. The ponds have the capacity to treat a dry weather flow of 80,000m3/d but currently treat only half this flow. Increased sewage strengths over and above the design value mean that although the hydraulic load is halved the organic surface load on the primary facultative ponds is only 37% below the design loading of 190kg BOD5/ha/d. The results of the ongoing monitoring programme show that effluent quality is good and meets WHO guidelines for unrestricted irrigation. Extrapolation of the existing results show that the system is performing to predictable efficiencies for the existing organic load and retention times (>90% BOD5 removal and >6 log reduction in FC) and will continue to do so as design flows and loads are reached. A pilot anaerobic pond study with what turns out to be full size anaerobics, showed BOD5 removal in excess of 80% in the single celled anaerobic ponds at design loadings of 240g/m3/d against a design prediction of 53% removal. Most importantly anaerobic pond loadings as low as 17-26% of the permissable volumetric loading maintained their efficiency without odour problems. This allows anaerobic ponds to be operated at flows well below design levels without risk of odour and without the need therefore to by-pass the anaerobics during commissioning and low initial flows. The benefits of land saving in the tropics by including anaerobic ponds in the system design is discussed as are the benefits of detailed monitoring programmes for large pond systems.

Occurrence and removal of Ascaris sp. ova by waste stabilisation ponds in Kenya

A study was conducted to determine the occurrence of Ascaris sp. ova in municipal wastewater and their removal by a variety of waste stabilisation pond systems in the republic of Kenya. A total of 52 wastewater samples were examined for the presence of ova, comprising 10 raw wastewater and 42 pond effluent samples over a two month period during 1990. Ascaris sp. ova were detected in 6 out of 10 designated pond systems examined. In raw wastewater, ova concentrations ranged from 17.5 to 133.3 ova/l and in pond effluents from 0.7 to 88.9 ova/l. Although the majority of ova were removed in primary ponds that received raw wastewater, ova were detected in pond effluents with estimated hydraulic retention times far in excess of estimated settling rates for Ascaris. The occurrence of ova in pond effluent samples suggested that in these multi-pond systems, estimated cumulative retention periods of 12.4 (Eldoret), 26.2 (Dandora) and 17.8 (Nakuru) days, respectively, were required to achieve an effluent free of Ascaris sp. ova. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to provide an indication of pond performance.

A demonstration of wastewater treatment for reuse applications in fish production and irrigation in Suez, Egypt

About 400 m3/d of raw sewage from the City of Suez were diverted and treated by two parallel pond systems. The first treatment system was conventional Waste Stabilization Ponds which included anaerobic, facultative, and maturation compartments for a total residence time of 21 days. The second system included a series of four plankton ponds with a total residence time in the order of 26 days. The effluent from these inexpensive, but yet effective treatment technologies, was found to conform to the World Health Organization (WHO) standards for unrestricted agricultural and aquacultural applications. The treated waste effluent was successfully used to grow two types of local fish, i.e.Oreochromis niloticus and Mugil sehli. Fish production, without supplemental feeding or pond aeration, reached 5-7 metric tons/hectare/year. Furthermore, the fish were found to be free from human parasites and safe for human consumption. The nutrient rich effluent from the fish pond was further used to grow trees and cultivate certain types of crops, i.e. barley, maize, beets and ornamental plants. This study clearly demonstrates the effectiveness and benefits of waste stabilization ponds systems for low cost treatment of domestic waste and the combined reuse in aquaculture and agriculture applications. In addition, the unique treatment/reuse facilities constructed at Suez will continue to function as an experimental station and serve scientists and engineers to study and to plan applications in Egypt and the region.

Performance of two municipal sewage stabilization pond systems with high and low loading in South-eastern Spain

From January to December 1992, the efficiency of two waste stabilization pond systems (WSPS) located in the Region of Murcia, South-eastern Spain, has been studied in terms of the physicochemistry and the microbiology of the systems. The efficiencies of the different stages of the treatment and the global performance have been compared. The WSPS of Lorquí and Ceutí (12,000 inhabitants) receives fruit processing and cannery wastes mixed with the urban sewage. This increases the load up to 95,000 equivalent inhabitants with an average BOD5 of 800 mgO2/l. Global reductions of COD and BOD5 were 79% and 73% as a yearly average. The mean of the reductions of indicator microorganisms were: coliphages (CHP), 83.14%; total coliforms (TC), 72.90%; faecal coliforms (FC), 93.84% and salmonellae (SAL), 98.29%. The WSPS of San Javier (15,000 inhabitants), situated at the border of the Mediterranean, does not receive industrial wastes but suffers from intrusions of marine waters into the sewers. BOD5 is diluted by the intrusion to less than 100 mgO2/l, even in summertime when population doubles because of the tourism. Average yearly reductions of COD and BOD5 were 32% and 21%. The means of the microbiological reductions were: CHP, 81.60%; TC, 90.77%; FC, 94.37% and SAL, 99.42%. Design constants have been calculated for both systems considering the climatic conditions of the area.

Evaluation of serratia marcescens bacteriophage as a tracer and a model for virus removal in waste stabilisation ponds

The use of Serratia marcescens bacteriophage as a tracer and a model for virus removal in the Cayman Islands' waste stabilisation ponds was investigated. A series of bench-scale experiments was designed and carried out to determine the survival of Serratia marcescens bacteriophage in the various stages of a waste stabilisation pond system. The study investigated whether the physico-chemical conditions expected in facultative and maturation ponds precluded the use of phage tracers. By the end of the 6th day, phage in filtered and unfiltered raw sewage and facultative pond samples, in normal sunlight, was undetectable. In the maturation pond samples, in normal sunlight, phage was undetectable by the 4th day. There was a high correlation between increased phage reduction and increased pH levels. The phage was still detectable on day 13 in maturation pond experiments kept in the dark. Therefore the study concluded that Serratia marcescens bacteriophage may be useful as a tracer in ponds with retention times up to 14 days provided average pH at the outlet is <9.0.

Rotavirus removal in experimental waste stabilization pond systems with different geometries and configurations

Rotavirus removal in waste stabilization ponds is a relatively slow process: in a series of ten ponds (a 1-d anaerobic pond followed by nine 2-d ponds) its numbers were reduced from 1.4 × 105 per litre to zero, and in an “innovative” series (a 1-day anaerobic pond, 3-d facultative pond, 3.8-d, 3-d and 5-d maturation ponds) from 5.1 × 104 per litre to <5 per litre. Faecal coliforms were better indicators of rotaviruses than was Clostridium perfringens .

Evaluation of a tropical single-cell waste stabilization pond system for irrigation

A single full-scale primary facultative pond in Sapé, north-east Brazil was monitored for performance and efficiency. The pond had a hydraulic retention time of 61 days and achieved a 95% BOD5 removal efficiency and had no helminth eggs in the effluent. The effluent failed to meet the WHO faecal coliform guideline for unrestricted irrigation. The pond was dominated by the cyanobacterium Microcystis and gave better than predicted orthophosphate removal. Details of how the system could be simply upgraded utilizing the same land are discussed.

Performance of two municipal sewage stabilization pond systems with high and low loading in south-eastern spain

From January to December 1992, the efficiency of two waste stabilization pond systems (WSPS) located in the Region of Murcia, South-eastern Spain, has been studied in terms of the physicochemistry and the microbiology of the systems. The efficiencies of the different stages of the treatment and the global performance have been compared. The WSPS of Lorquí and Ceutí (12,000 inhabitants) receives fruit processing and cannery wastes mixed with the urban sewage. This increases the load up to 95,000 equivalent inhabitants with an average BOD5 of 800 mgO2/t. Global reductions of COD and BOD5 were 79% and 73% as a yearly average. The mean of the reductions of indicator microorganisms were: coliphages (CHP), 83.14%; total coliforms (TC), 72.90%; faecal coliforms (FC), 93.84% and salmonellae (SAL), 98.29%. The WSPS of San Javier (15,000 inhabitants), situated at the border of the Mediterranean, does not receive industrial wastes but suffers from intrusions of marine waters into the sewers. BOD5 is diluted by the intrusion to less than 100 mgO2/l, even in summertime when population doubles because of the tourism. Average yearly reductions of COD and BOD5 were 32% and 21 %. The means of the microbiological reductions were: CHP, 81.60%; TC, 90.77%; FC, 94.37% and SAL, 99.42%. Design constants have been calculated for both systems considering the climatic conditions of the area.

A demonstration of wastewater treatment for reuse applications in fish production and irrigation in Suez, Egypt

About 400 m3/d of raw sewage from the City of Suez were diverted and treated by two parallel pond systems. The first treatment system was conventional Waste Stabilization Ponds which included anaerobic, facultative, and maturation compartments for a total residence time of 21 days. The second system included a series of four plankton ponds with a total residence time in the order of 26 days. The effluent from these inexpensive, but yet effective treatment technologies, was found to conform to the World Health Organization (WHO) standards for unrestricted agricultural and aquacultural applications. The treated waste effluent was successfully used to grow two types of local fish, i.e. Oreochromis niloticus and Mugil sehli. Fish production, without supplemental feeding or pond aeration, reached 5–7 metric tons/hectare/year. Furthermore, the fish were found to be free from human parasites and safe for human consumption. The nutrient rich effluent from the fish pond was further used to grow trees and cultivate certain types of crops, i.e. barley, maize, beets and ornamental plants. This study clearly demonstrates the effectiveness and benefits of waste stabilization ponds systems for low cost treatment of domestic waste and the combined reuse in aquaculture and agriculture applications. In addition, the unique treatment/reuse facilities constructed at Suez will continue to function as an experimental station and serve scientists and engineers to study and to plan applications in Egypt and the region.

Evaluation of a tropical single-cell waste stabilization pond system for irrigation

A single full-scale primary facultative pond in Sapé, north-east Brazil was monitored for performance and efficiency. The pond had a hydraulic retention time of 61 days and achieved a 95% BOD5 removal efficiency and had no helminth eggs in the effluent. The effluent failed to meet the WHO faecal coliform guideline for unrestricted irrigation. The pond was dominated by the cyanobacterium Microcystis and gave better than predicted orthophosphate removal. Details of how the system could be simply upgraded utilizing the same land are discussed.

Rotavirus removal in experimental waste stabilization pond systems with different geometries and configurations

Rotavirus removal in waste stabilization ponds is a relatively slow process: in a series of ten ponds (a 1-d anaerobic pond followed by nine 2-d ponds) its numbers were reduced from 1.4 x 105 per litre to zero, and in an “innovative” serves (a 1-day anaerobic pond, 3-d facultative pond, 3.8-d, 3-d and 5-d maturation ponds) from 5.1 x 104 per litre to <5 per litre. Faecal coliforms were better indicators of rotaviruses than was Clostridium perfringens.

Evaluation of Serratia marcescens bacteriophage as a tracer and a model for virus removal in waste stabilisation ponds

The use of Serratia marcescens bacteriophage as a tracer and a model for virus removal in the Cayman Islands' waste stabilisation ponds was investigated. A series of bench-scale experiments was designed and carried out to determine the survival of Serratia marcescens bacteriophage in the various stages of a waste stabilisation pond system. The study investigated whether the physico-chemical conditions expected in facultative and maturation ponds precluded the use of phage tracers. By the end of the 6th day, phage in filtered and unfiltered raw sewage and facultative pond samples, in normal sunlight, was undetectable. In the maturation pond samples,in normal sunlight, phage was undetectable by the 4th day. There was a high correlation between increased phage reduction and increased pH levels. The phage was still detectable on day 13 in maturation pond experiments kept in the dark. Therefore the study concluded that Serratia marcescens bacteriophage may be useful as a tracer in ponds with retention times up to 14 days provided average pH at the outlet is <9.0.

Ecoclimatic influence on waste stabilization ponds (WSP) efficiencies. Case study of the sesimbra system

Portugal has a great diversity of ecoclimatic areas and Sesimbra was chosen to carry out a study on WSP efficiencies over five years (1989 to 1993). According to Pina Manique &amp; Albuquerque (1954), the climate is classified as Atlantic Mediterranean (AM). Some environmental and climatic parameters have been studied in order to define the area. The treatment system at Sesimbra has three ponds: anaerobic, facultative and maturation. The physical and chemical parameters studied in the WSP system were: Temperature, pH, Dissolved Oxygen, Conductivity, BOD5, COD, nitrates, nitrites, ammonia and total nitrogen, total and volatile suspended solids, total phosphorus and orthophosphates. Algal populations and the following microbiological parameters were studied: total and fecal coliforms, fecal Streptococci, Clostridium perfringens, Pseudomonas aeruginosa and some Enterobacteriaceae. The K and K20 kinetic parameters were studied and derived for the three ponds utilizing the seasonal regional characteristics from the surrounding area. These values were then correlated with temperature and the subsequent removal efficiencies for each pond deduced. The data obtained indicate a necessity to determine the seasonal fluctuations of the K and K20 kinetic parameters for the WSP systems.

Occurrence and Removal of Cryptosporidium spp. Oocysts and Giardia spp. Cysts in Kenyan Waste Stabilisation Ponds

This study was designed to determine tlie occurrence and removal of Cryptosporidium spp. oocysts and Giardia spp. cysts, in municipal waste-water by waste stabilisation ponds in tlie Republic of Kenya. Eleven waste stabilisation pond systems located in towns across Kenya were included. A total of 66 waste-water samples were examined for the presence of oocysts and cysts, comprising 11 raw waste-water and 55 pond effluent samples over a two month period. Cryptosporidium spp. oocysts were detected in 6 and Giardia spp. cysts in 9 of the designated pond systems analysed demonstrating their ubiquitous nature throughout Kenya. Oocyst levels detected in raw waste-water samples ranged from 12.5 - 72.97 oocysts/l and various pond effluents between 2.25 - 50 oocysts/l. Cyst levels detected in raw waste-water samples ranged from 212.5 to 6212.5 cysts/l and in various pond effluents from 3.125 to 230.7 cysts/l. No Cryptosporidium spp. oocysts were detected in the final effluent from any pond systems studied (11/11). Whereas no Giardia spp. cysts were detected in the final effluent from 10 of 11 waste stabilisation pond systems studied, one pond system was found to be consistently discharging cysts in the final effluent at concentrations ranging from 40 to 50 cysts/l. The minimum retention period for the removal of Cryptosporidium spp. oocysts and Giardia spp. cysts was 37.3 days. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to express relationships between pond performance and protozoa removal.

Efficiency of Faecal Bacterial Removal in Waste Stabilisation Ponds in Kenya

Results for faecal coliform die-off rates are presented for seven different waste stabilisation pond systems in Kenya, which were sampled as part of a national pond monitoring and evaluation study carried out during 1988-1989. The results showed that average die-off rates through each pond series were considerably lower than those predicted from traditional design equations which are based on temperature (Marais 1974). Die-off rates were surprisingly higher in the primary ponds, which are designed for BOD removal, than in the maturation ponds which are designed for pathogen removal. Good correlations were found between faecal coliform first order removal rate constants and (a) temperature for the pond series as a whole, and (b) influent faecal coliform concentration for individual ponds.