Some effects of stocking fish in waste treatment ponds

Oxidation ponds or sewage lagoons often present characteristics of natural water bodies in an extreme state of ecological imbalance. Excess nutrients of the decaying waste give rise to plankton blooms which subsequently die. In such conditions dissolved oxygen concentrations (DO) in the water are often low and the pH depressed. The addition of fish to ponds which twice a week received, per ha, wastes with a 5 day BOD of up to 800 kg (20°C) and 5600 kg solids, reduced plankton and benthic populations, increased the average DO, and raised the pH. All of these changes improve the effectiveness of a waste treatment pond for reducing BOD and removing nutrients from the water. Bacteria concentrations were as much as 15 times lower in treatment ponds stocked with fish as compared with unstocked ponds. Lower bacteria concentrations however reduced the rate of loss of COD in the solids of the waste.     

Fate of physical,chemical, and microbial contaminants in domestic wastewater following treatment by small constructed wetlands

In order to evaluate the efficacy of constructed wetlands for treatment of domestic wastewater for small communities located in rural areas, small-scale wetland mesocosms (400 L each) containing two treatment designs (a mixture of Typha, Scirpus, and Juncus species; control without vegetation) were planted into two depths (45 or 60 cm) with pea gravel. Each mesocosm received 19 L/day of primary-treated domestic sewage. Mesocosms were monitored (inflow and outflow samples) on a monthly basis over a 2-year period for pH, total suspended solids (TSS), 5-day biochemical oxygen demand (BOD(5)), total Kjeldahl nitrogen (TKN), dissolved oxygen (DO), and conductivity. Microbiological analyses included enumeration of fecal coliforms, enterococci, Salmonella, Shigella, Yersinia, and coliphage. Significant differences between influent and effluent water quality for the vegetated wetlands (p<0.05) were observed in TSS, BOD(5), and TKN. Increased DO and reduction in fecal coliform, enterococcus, Salmonella, Shigella, Yersinia, and coliphage populations also were observed in vegetated wetlands. Greatest microbial reductions were observed in the planted mesocosms compared to those lacking vegetation. Despite marked reduction of several contaminants, wetland-treated effluents did not consistently meet final discharge limits for receiving bodies of water. Removal efficiencies for bacteria and several chemical parameters were more apparent during the initial year compared to the second year of operation, suggesting concern for long-term efficiency and stability of such wetlands.     

Probable causes for reduced BOD test results in hypersaline wastewaters

The causes for erratic BOD results from wastewaters containing elevated concentrations of salt were investigated. Standard organic solutions and an industrial waste were tested with sewage seed and known species of salt tolerant bacteria using standard and hypersaline dilution water at three salt concentrations. Significant BOD differences were found when saline wastes were diluted with standard (non-saline) BOD dilution water. Bacterial populations to genera were monitored and it was shown that equivalent numbers of bacteria did not have the same capability to degrade a given amount of waste with increases in salt concentrations to the 3% level. Seeding of hypersaline wastewaters with known salt tolerant species is recommended for consistent BOD results.     

A membrane filter method for the enumeration of aquatic ammonifiers

A standard procedure for the enumeration of heterotrophic bacteria, utilizing heterotrophic plate count medium (m-HPC), has been modified to allow bacterial ammonifier populations also to be counted. Nessler's reagent was included as an outside indicator to ascertain what portion of the population is capable of ammonification. Typically the ammonifier population varied among aquatic habitats, ranging from 0.08 to 37.0% of the heterotrophic population in river water samples, 0.2 to 10.6% for irrigation water samples, and 1.4 to 3.0% for pond and lake water samples.     

Temperature influence on bacterial populations in three aquatic systems

Effects of temperature changes on bacterial populations in three aquatic systems were studied in the Thermal Effects Laboratory of the USAEC's Savannah River Laboratory. At monthly intervals for 12 months, total plate counts and diversity of heterotrophic, mesophilic bacteria were determined from a natural stream, two artificial streams, and two outdoor ponds. Water for artificial systems was drawn from the natural stream.Effects of changes in ambient temperature were analyzed in natural and artificial streams and in an unheated pond. A second pond was heated above natural stream temperature. Temperature elevation resulted in increased total plate counts in each system. Bacterial diversity increased in all systems during the initial 3–4°C increase in temperature. However, a reduction in diversity occurred when temperature was maintained 4–10°C above the initial ambient temperature. Changes were observed in both nutritional types and genera.     

Environmental distribution of Zoogloea strains

Enrichment culture techniques were employed to examine the environmental distribution of fingered zoogloea (FZ)-forming bacteria. FZ were detected in surface films of cultures started with various wastewaters, polluted pond and stream waters, duck feces, garbage disposal wastes and fish aquarium waters, but were not observed in cultures started with food scraps or soils. According to most probable number estimates of FZ-forming bacteria and total populations formed in enrichment cultures. less than 0.01% of the viable bacterial population in domestic wastewater and aerobic mixed liquor suspended solids (MLSS) contained the specific zoogloea-forming bacteria. However, FZ-forming bacteria were present in 10-fold greater concentrations in MLSS than in the raw wastewater solids.An isolation procedure, employing an inoculum of concentrated and sonically treated washed FZ yielded 70 strains of zoogloea-producing bacteria, 61 of which formed typical finger-like zoogloeae in pure culture. Isolates were removed also by direct streaking of enrichment culture films. The bacteria were isolated from enrichment cultures started with raw wastewaters, polluted pond waters, greenhouse drainage, fish aquarium water and duck feces. The zoogloea-producing strains were gram negative, motile rods possessing catalase and oxidase and the ability to denitrify, hydrolyze gelatin in plates and meta cleave m-toluic acid. Certain biochemical activities were located among isolates in relation to the various habitats from which they originated. The bacteria were considered to be strains of Zoogloea ramigera.     

Effect of chemical and physical parameters on a pulp mill biotreatment bacterial community

The bacterial community composition in an activated sludge plant treatment from a bleached kraft pulp mill was monitored over a period of 209 days. Using DGGE and terminal-Restriction Fragment Length Polymorphism (t-RFLP) analysis we generated community DNA fingerprints over the time period. Both methods produce fingerprints that can be used to monitor stability in the system and generate fragments that can be associated with bacterial taxa. Chemical and physical parameters were also collected during that same time frame. We found a number of significant correlations with influent variables such as temperature, chemical oxygen demand (COD), Biochemical oxygen demand (BOD) and chloroform concentrations suggesting that these were the most likely parameters to influence the bacterial community structure. In addition several taxa correlated to important performance indicators such as COD/BOD removals and SVI. Multivariate analysis also confirmed the strong links between taxa variation and temperature, nutrient loads, chloroform and also one class of filaments. Establishing the identity of these taxa and their ecological preferences will greatly enhance our understanding and management of biological treatment systems.     

The effect of physicochemical, phytoplankton and seasonal factors on faecal indicator bacteria in northern brackish water

The relationships existing between the numbers of coliforms, faecal coliforms, faecal streptococci, C. perfringens, certain physicochemical parameters, phytoplankton, and seasonal factors in an eutrophic northern brackish water were investigated during a period of 1 year. Seasonal fluctuation of the faecal indicator bacteria was noted. A highly significant correlation was found between the non spore-forming faecal indicator bacteria examined. Of the physicochemical parameters examined the pH-value and temperature were found to have the most effect on the number of faecal indicator bacteria but nutrients, especially total nitrogen and nitrate nitrogen were also significant. The lack of correlation between C. perfringens and the other indicator bacteria was found to be related, in part, to the variation in pH. Thus C. perfringens can be considered as a useful indicator in ecosystems having stress factors. The results in this study show that many stress factors affect the number of faecal indicator bacteria. Therefore it is necessary to estimate the quality of water using a combination of several parameters.     

Indicator bacteria for fecal pollution in the littoral zone of Lake Kinneret

The distribution of fecal indicator bacteria in the littoral zone of Lake Kinneret have been monitored over seasons, geographical zones, station type (bathing beaches and streams), distance from shore line and water depth. Statistical analysis was used to determine the impact of these factors. The dominant contamination source are water streams flowing during winter; bacterial numbers were higher in zones where the proportion of stream type stations is higher. Bacterial numbers in water and sediment were higher close to the shore line.     

Spatial analysis of water quality trends in the Han River basin, South Korea

Spatial patterns of water quality trends for 118 sites in the Han River basin of South Korea were examined for eight parameters-temperature, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended sediment (SS), total phosphorus (TP), and total nitrogen (TN). A non-parametric seasonal Mann-Kendall's test determined the significance of trends for each parameter for each site between 1993 and 2002. There are no significant trends in temperature, but TN concentrations increased for the majority of the monitoring stations. DO, BOD, COD, pH, SS, and TP show increasing or decreasing trends with approximately half of the stations exhibiting no trends. Urban land cover is positively associated with increases in water pollution and included as an important explanatory variable for the variations in all water quality parameters except pH. Topography and soil factors further explain the spatial variations in pH, COD, BOD, and SS. BOD, COD, SS, and TP variations are consistently better explained by 100m buffer scale analysis, but DO are better explained by the whole basin scale analysis. Local water quality management or geology could further explain some variations of water quality. Non-point-source pollution exhibits strong positive spatial autocorrelation as measured by Moran's I, indicating that the incorporation of spatial dimensions into water quality assessment enhances our understanding of spatial patterns of water quality. The spatial regression models, compared to ordinary least square (OLS) models, always better explain the variations in water quality. This study suggests that spatial analysis of watershed data at different scales should be a vital part of identifying the fundamental spatio-temporal distribution of water quality.     

Bacterial communities of leachate from tire monofill disposal sites

The disposal of used automobile tires is problematic due to the large number generated each year. Newer methods of tire disposal have been developed in which tires are shredded and used for construction materials or buried in dedicated tire monofill sites. In this study, the bacterial assemblage associated with aqueous leachate collected from tire monofill sites was examined and compared to the bacterial assemblage of reference streams. Leachate from two tire monofill sites in Ohio (USA) was collected four times during the course of one year and analyzed for total bacterial number, culturable bacterial number, and number of the bacterium Acinetobacter calcoaceticus. The numbers of culturable bacteria (CFU/ml), total bacteria (cells/ml), and A. calcoaceticus (cells/ml) from the leachate at both monofill sites were generally lower or equal to numbers from the reference streams. Exceptions occurred during February when culturable bacteria at one site and total bacteria at the other site were more abundant in the leachate compared to reference streams; correspondingly the leachate temperature in February was higher than the surface waters. Culturable bacteria, total bacteria, and A. calcoaceticus numbers in the leachate ranged from 5.7 x 10(2)-1.8 x 10(4), 5.3 x 10(5)-3.8 x 10(6), and 9.9 x 10(1)-1.8 x 10(4) respectively. Twenty isolates were selected for species identification using FAME analysis. Nine of the 17 identified isolates belonged to the genus Pseudomonas and two isolates each belonged to the Flavobacterium and Aeromonas genera. The culturable bacterial assemblage of tire leachate was found to be similar to natural surface waters.     

Cadmium induced adaptive responses of certain biogeochemical cycling bacteria in an aquatic system

The population growth of some biogeochemical cycling bacteria (heterotrophic bacteria (HB), ammonifying bacteria (AB), ammonia oxidizing bacteria (AOB), denitrifying bacteria (DNB) and cellulose decomposing bacteria (CDB)), as well as ammonification, and denitrification rates were determined in simulated pond systems treated with full doses (FDs) and split doses (SDs) of cadmium. Reductions in bacterial density and nitrogen activity rates were more severe for the FD and SD followed by a slight recovery in both. Among the test groups, reductions were maximal in the AOB and DNB and lowest for the CDB populations, suggesting that the latter had greater potential for cadmium resistance. Bicarbonate alkalinity of water was found to exert a profound influence in counteracting cadmium stress in the system, as strong negative correlations between this parameter and bacterial mass were evident in the SD treatment. Though the aquatic microbial populations were greatly altered by cadmium stress, the normal operating range of the system was restored at a later time with the CDB population showing higher degree of adaptive responses.     

Greywater treatment and reuse results from a 50-person trial

The paper describes a seven year project to develop a greywater treatment plant for lavatory flushing. Site surveys and laboratory research was used to produce a design for a 50-person residential University hall. The final design included a balancing tank (13:1 peak to average capacity) screening (5 mm), a moving bed bioreactor and alternating deep bed double filtration (reticulated foam). The plant achieved a recycled water quality of 3 mg/l biochemical oxygen demand (BOD) (used as an indicator of odour potential and regrowth) a water clarity of 2 nephelometric turbidity units (NTU) and 2 mg/l suspended solids. Ultra violet (UV) disinfection was added to meet the UK guidelines of zero microbial indicator organisms. The demonstration trial lasted 5 years and users were unable to differentiate between the recycled water and mains water in the blind trial.     

Assessing the effectiveness of regulatory controls on farm pollution using chemical and biological indices of water quality and pollution statistics

Water quality was measured in 42 streams in the Colebrooke and Upper Bann catchments in Northern Ireland over the period 1990-1998. Despite ongoing pollution control measures, biological water quality, as determined by the invertebrate average score per taxon (ASPT) index, did not improve and there was no appreciable decline in recorded farm pollution incidents. However, the lack of decline in pollution incidents could reflect changes in detection policy, as a greater proportion of incidents were recorded from less polluting discharges such as farm-yard runoff. In contrast, there was an improvement during 1997 and 1998 in annual chemical water quality classification based on exceedence values (90th percentiles) for dissolved oxygen, ammonium and BOD concentrations. In 1998, 11.9% of streams were severely polluted compared to 26.2% in 1990, while the proportion classed as of salmonid water quality, increased from 40.5% in 1990 to 59.6% in 1998. Although water quality in 1996 did not improve relative to 1990 values, there was a notable increasing trend from 1990 in the numbers of samples taken during the summer which had good water quality with low ammonium (<0.6mgN l(-1)) and high dissolved oxygen (> 70% sat). The trend for samples with low BOD (<4 mgl(-1)) was more erratic, but an improvement was apparent from 1994. These improvements in chemical water quality suggest that point-source farm pollution declined after 1990. The fact that this was not reflected in stream biology may reflect the limited time scale for biological recovery. An important factor preventing biological recovery may be the high pollution capacity of manures and silage effluent, so that even reduced numbers of farm pollution incidents can severely perturb stream ecosystems. The intractable nature of farm pollution suggests that there is a need to consider an interactive approach to problem resolution involving both farmers and regulators.     

Sunlight, season, snowmelt, storm, and source affect E. coli populations in an artificially ponded stream

Reducing fecal indicator bacteria, such as Escherichia coli (E. coli), in streams is important for many downstream areas. E. coli concentrations within streams may be reduced by intervening ponds or wetlands through a number of physical and biological means. A section of Dunes Creek, a small coastal stream of southern Lake Michigan, was impounded and studied for 30 months from pre-through post-construction of the experimental pond. E. coli reduction became more predictable and effective with pond age. E. coli followed the hydrograph and increased several-fold during both rainfall and snowmelt events. Seasonally, the pond was more effective at reducing E. coli during summer than winter. Late summer, non-solar reduction or inactivation of E. coli in the pond was estimated at 72% and solar inactivation at 26%. E. coli DNA fingerprinting demonstrated that the winter population was genetically more homogeneous than the summer population. Detection of FRNA coliphages suggests that there was fecal contamination during heavy rain events. An understanding of how environmental factors interact with E. coli populations is important for assessing anticipated contaminant loading and the reduction of indicator bacteria in downstream reaches.     

Impact of population and latrines on fecal contamination of ponds in rural Bangladesh

A majority of households in Bangladesh rely on pond water for hygiene. Exposure to pond water fecal contamination could therefore still contribute to diarrheal disease despite the installation of numerous tubewells for drinking. The objectives of this study are to determine the predominant sources (human or livestock) of fecal pollution in ponds and examine the association between local population, latrine density, latrine quality and concentrations of fecal bacteria and pathogens in pond water. Forty-three ponds were analyzed for E. coli using culture-based methods and E. coli, Bacteroidales and adenovirus using quantitative PCR. Population and sanitation spatial data were collected and measured against pond fecal contamination. Humans were the dominant source of fecal contamination in 79% of the ponds according to Bacteroidales measurements. Ponds directly receiving latrine effluent had the highest concentrations of fecal indicator bacteria (up to 10⁶ Most Probable Number (MPN) of culturable E. coli per 100 mL). Concentrations of fecal indicator bacteria correlated with population surveyed within a distance of 30-70 m (p < 0.05) and total latrines surveyed within 50-70 m (p < 0.05). Unsanitary latrines (visible effluent or open pits) within the pond drainage basin were also significantly correlated to fecal indicator concentrations (p < 0.05). Water in the vast majority of the surveyed ponds contained unsafe levels of fecal contamination attributable primarily to unsanitary latrines, and to lesser extent, to sanitary latrines and cattle. Since the majority of fecal pollution is derived from human waste, continued use of pond water could help explain the persistence of diarrheal disease in rural South Asia.     

Use of in-stream reservoirs to reduce bacterial contamination of rural watersheds

An investigation into bacterial water quality problems was conducted on an interconnected stream and irrigation system within the Oldman River Basin of southern Alberta, Canada. Levels of indicator bacteria, including fecal coliforms, generic Escherichia coli and fecal streptococci, were repeatedly measured in streams and irrigation return canals of this river basin during the summer of 2001. Bacterial-loading segments of the irrigation/stream system were identified through a comparison of indicator bacteria levels in pairs of upstream and downstream sites. Mann-Whitney U-tests indicated that reservoirs significantly reduced bacterial counts. A temporal comparison of E. coli counts and river discharges suggested that these indicator bacteria do not originate from within in-stream sediments. Site-specific as well as cumulative inputs from a variety of non-point sources are likely to be responsible for the high downstream levels of indicator bacteria in this water system. The use of management practices such as in-stream reservoirs may significantly reduce contamination, and increase the quality of limited rural water supplies to allow their reuse and safe discharge into downstream water sources. The identification of bacteria-loading river/canal segments could also be used to prioritize restoration projects.     

Soft deposits, the key site for microbial growth in drinking water distribution networks

In this project we studied the microbiological quality of soft pipeline deposits removed from drinking water distribution networks during mechanical cleaning. Drinking water and deposit samples were collected from 16 drinking water distribution networks located at eight towns in different parts of Finland. Soft pipeline deposits were found to be the key site for microbial growth in the distribution networks. The microbial numbers in the soft deposits were significantly higher than numbers in running water. The highest microbial numbers were detected in the main deposit pushed ahead by the first swab. The deposits contained high numbers of heterotrophic bacteria, actinomycetes and fungi. Also coliform bacteria were often isolated from deposit samples. Manganese and copper in the deposits correlated negatively with the numbers of heterotrophic bacteria. After a year, the viable microbial numbers in the new deposits were almost as high as in the old deposits before the first mechanical cleaning. The bacterial biomass production was higher in the new than in the old deposits.     

Survival dynamics of fecal bacteria in ponds in agricultural watersheds of the Piedmont and Coastal Plain of Georgia

Animal agriculture in watersheds produces manure bacteria that may contaminate surface waters and put public health at risk. We measured fecal indicator bacteria (commensal Escherichia coli and fecal enterococci) and manure pathogens (Salmonella and E. coli 0157:H7), and physical-chemical parameters in pond inflow, within pond, pond outflow, and pond sediments in three ponds in agricultural watersheds. Bishop Pond with perennial inflow and outflow is located in the Piedmont, and Ponds A and C with ephemeral inflow and outflow in the Coastal Plain of Georgia. Bromide and chloride tracer experiments at Bishop Pond reflected a residence time much greater than that estimated by two models, and indicated that complete mixing within Bishop Pond was never obtained. The long residence time meant that fecal bacteria were exposed to solar UV-radiation and microbial predation. At Bishop Pond outflow concentrations of fecal indicator bacteria were significantly less than inflow concentrations; such was not observed at Ponds A and C. Both Salmonella and E. coli 0157:H7 were measured when concomitant concentrations of commensal E. coli were below the criterion for surface water impairment indicating problems with the effectiveness of indicator organisms. Bishop Pond improved down stream water quality; whereas, Ponds A and C with ephemeral inflow and outflow and possibly greater nutrient concentrations within the two ponds appeared to be less effective in improving down stream water quality.     

Determining the domestic specific loads of two wastewater plants of the Paris conurbation (France) with contrasted treatments: a step for exploring the effects of the application of the European Directive

The effluents of wastewater treatment plants (WTTP) discharged into the rivers considerably affect the biogeochemical functioning of the system. In this paper, we characterize both raw and treated domestic wastewater from two WTTPs of Parisian agglomeration using different process treatments (Achères WWTP with a secondary treatment and Colombes WWTP with a tertiary one). In addition to the classical variables, we analyse the input of bacteria, both the heterotrophs and the nitrifyers. Tertiary treatment leads to significantly decrease ammonium-specific load (< 2 g KjN inhab equ.(-1) instead of 9 g KjN inhab equ.(-1) for secondary treatment) and notably reduces the one of organic matter (approximately 2.5 g biological oxygen demand (BOD) inhab equ.(-1) instead of approximately 7.5 g BOD inhab equ.(-1) for secondary treatment); it is therefore promising to improve oxygen status of both the Seine river and its estuary. In terms of total bacterial biomass abatement (the heterotrophs mostly), bioreactors (at Colombes WWTP) eliminate 12% more bacterial biomass than the activated sludge treatment (at Achères WWTP). Regarding the nitrifying bacteria, a tertiary treatment in bioreactors eliminates reverse similar 90% of both nitrifying bacteria and nitrogen pollution of wastewater. Bacterial populations are characterized by large size bacteria (> 1 microm) with a higher growth rate, that represent in the treatment plant effluents 70% of the biomass. These large size bacteria have therefore a strong impact in the organic matter degradation and oxygen consumption. Relationships between classical physical-chemical variables routinely analysed in WWTPs laboratory and bacterial biomass (heterotrophic and nitrifying) are established, in order to quantify the ecological role of the allochthonous bacteria brought into the river system. In addition, domestic specific loads are calculated for both raw and treated effluents of the two types of WWTPs. As the application of the European Water Directive requires to upgrade the wastewater treatment at Achères WWTP as soon as 2007 for 90% nitrification and 30% denitrification and in 2015 for further denitrification (up to 70%), the results of this study can be taken as point-source constraints into the modelling approach already developed for the Seine basin, and chosen to test the implementation of the Water Frame Directive.