Fecal Coliform Densities Research Articles

Spatial and rainfall related patterns of bacterial contamination in Sydney Harbour estuary

Water quality in recreational areas in Sydney Harbour, Australia, was analysed first to identify spatial patterns in faecal coliform and enterococci densities, and then to determine the relationship between bacterial densities and catchment rainfall. Non-metric multidimensional scaling separated sites closest to the mouth of the harbour from those further up the harbour's west and north-west arms. Sites closest to the harbour mouth generally had lower frequencies of high bacterial densities that exceeded median water quality guideline values. We attribute this to greater tidal flushing at sites closer to the harbour mouth. Eight site groups were identified within the harbour. Within each group, multiple regression analyses indicated rainfall accounted for between 15 and 66% of the variability in the bacterial densities. Variation in bacterial densities explained by rainfall was lower for sites closer to the harbour mouth where tidal flushing is greatest. Thus, our findings indicate that simple rainfall-based regression models are appropriate for predicting bacterial concentrations when flushing at a site is limited. More complex models incorporating a suite of environmental variables may improve the ability to predict bacterial concentrations at well-flushed sites, but even then, their predictive ability may be low.

Determining the Critical Bulking Agent Requirement For Municipal Biosolids Composting

Air space within municipal biosolids composting feedstock is an important design and operating consideration. Bulking agents, such as woodchips, are required to ensure adequate air space levels are maintained. The purpose of the study was to report on the use of bench-scale air space tests to identify the critical bulking agent requirement (CBAR). CBAR was defined as the minimum amount of bulking agent required to maintain adequate pore space oxygen levels. Bench-scale air space tests were correlated to full-scale windrow composting performance, particularly pore space oxygen levels. Four volumetric ratios of municipal biosolids and woodchips were tested ranging from 1:1 to 1:4 (biosolids:wood-chips). The traditional soil physics methodology was used to determine total air space (TAS). A new step was added to the method which allowed one to also determine the free air space (FAS) within the sample. In addition, the effect of compaction on TAS and FAS was also investigated. Windrows were monitored for pile temperature and pore space oxygen concentration. At the end of the run, maturity, fecal coliform density, and the presence of salmonella were determined. The heavy metal content of the feedstock material, finished compost, and recycled woodchips were also determined. For the materials tested, biosolids and woodchips, the CBARs, to achieve a FAS of ≥20% and a minimum pore space oxygen content of ≥5%, were estimated as 1:2.5 and 1:2.8 (biosolids:woodchips; vol:vol), respectively. Assuming a target pore space oxygen level of > 5%, the recommended air space value depended on the test method used, and ranged from 26 to 61%. Bench-scale air space values were found to correlate to windrow pore space oxygen levels and operating temperature. A significant thermophilic period was not observed in any of the recipes tested. It was speculated this was caused by the coarse particle size of the woodchips. Based on the observations of the metal contents of the materials used in this investigation, the metal content of recycled material should be considered when evaluating the advantages and disadvantages of using recycled woodchips as a bulking agent.

STORM AND SEASONAL DISTRIBUTIONS OF FECAL COLIFORMS AND CRYPTOSPORIDIUM IN A SPRING1

ABSTRACT: The transmission of disease in ground water is a topic of great concern to government agencies, ground water specialists, and the general public. The purpose of this study was to compare the temporal variability in storm flow of fecal coliform bacteria densities and Cryptosporidium parvum oocyst densities in agriculturally impacted karst ground water. Cryptosporidium parvum oocyst densities ranged from 0 to 1,050 oocysts/1, and mean storm densities ranged from 3.5 to 156.8 oocysts/1. Fecal coliform densities ranged from less than 1 CFU/100ml to more than 40,000 CFU/100ml, and geometric mean storm densities ranged from 1.7 CFU/100ml to more than 7,000 CFU/100ml. Fecal coliform densities correlated well with flow during storms, but Cryptosporidium oocyst densities exhibited a great deal of sample to sample variability and were not correlated with flow. Fecal coliform densities did not correlate positively with Cryptosporidium oocyst densities. Fecal coliform densities were greatest at storm peaks, when sediment loads were also greatest. Multiple transport mechanisms for fecal coliform bacteria and C. parvum oocysts may necessitate various agricultural land management and livestock health maintenance practices to control movement of pathogens to karst ground water.

Using geographic information systems and regression analysis to evaluate relationships between land use and fecal coliform bacterial pollution

Geographic Information Systems (GIS) and regression modeling techniques were used to evaluate relationships between land use and fecal pollution in Murrells Inlet, a small, urbanized, high-salinity estuary located between Myrtle Beach and Georgetown, SC. GIS techniques were used to identify and calculate land use and spatial variables to be used in a regression model. The regression analysis was performed to identify specific land-use characteristics that may influence fecal coliform densities in the estuary. The regression modeling used land-use parameters to explain the variability of fecal coliform densities measured monthly at 21 locations in the estuary over the 10-year period from 1989 to 1998. Individual regression models were generated for each season, and for a combined data set. The results of the regression analyses indicate that proximity to areas with septic tanks, and rainfall runoff from urbanized areas are important predictors of fecal coliform densities in the estuary. Sampling sites closer to areas with high densities of active septic tanks or more urbanized land uses tended to have higher fecal coliform densities. Although these results may suggest that septic tanks are a substantial human source of fecal pollution, previous research has indicated that the fecal pollution in those areas is probably not from human sources. The areas of Murrells Inlet with higher septic tank densities also are located in areas of high housing density, are in close proximity to the land–water interface, and are in the extreme upper reaches of the estuary, where flushing and dilution effects may be reduced. The higher fecal coliform densities observed at these locations may be a coincidental result of these factors and fecal deposition from pets, and not the direct result of fecal pollution input from the septic tanks. The results also show seasonal differences in the dynamics of fecal coliform bacterial pollution in the estuary. The winter model included a rainfall interaction term, which indicates that ground saturation effects may be an important part of fecal deposition in winter months. The water quality management implications of this research include identification of strategies to reduce or intercept urban stormwater runoff, reduction of waste dumping from boats, and reduction of pet waste.

Compact vertical flow constructed wetland systems - first two years’ performance

In order to move towards optimising wastewater treatment performance by vertical down-flow reed beds, user and installer demands were applied to design, resulting in the "compact vertical flow reed bed" (CVF bed). Performance data are presented for the two years since commissioning a CVF bed and pond system serving eight residents. Particular emphasis was placed on investigating oxygen transfer rate and susceptibility to hydraulic overloading. Average percentage concentration reduction effected by single passage through the bed exceeded 97% for suspended solids and biochemical oxygen demand, and 90% for ammoniacal nitrogen and total Kjeldahl nitrogen. The occurrence of nitrification and denitrification (up to 58%) within the same bed was clearly indicated. Percentage ortho-phosphate removal averaged 92% over the first 17 months' operation and thereafter fell to approximately 45%. Faecal coliform density underwent an almost four log reduction. Oxygen transfer rate within the reed bed was between 28-36 gO2/m2 x d. Normal operation was maintained until six times dry weather hydraulic load rate was exceeded, at which point surface flooding occurred. The capacity of a single vertical flow reed bed to achieve effective treatment of domestic sewage was demonstrated, with no requirement for reduced load rates, promising substantial advantages over established approaches.

Characterization and dewaterability of raw and stabilized sludge using different treatment methods

A comparison of the characteristics and stabilization potential of the four most used sludge treatment systems in Mexico was made. A pilot plant constituted by separate systems for anaerobic and aerobic digestion, lime stabilization, conditioning and dewatering, was built and operated during four months in one of the biological wastewater treatment plants in Acapulco, Mexico. Composting of sludge was also made. An aerobic static pile was built using bulking materials available in the region. A turbine centrifuge was used for dewatering the stabilized sludge and results showed good performance of the device. The main problem for the beneficial use of treated sludge was its pathogenicity. The composting process allowed us to obtain a product with approximately 20 fecal coliform density (MPN/g); with lime stabilization, the sludge produced had a fecal coliform density of 2 MPN/g. From these results, it is concluded that both the composting process and the alkaline stabilization with lime produce a well stabilized sludge, bacteriologically safe that accomplishes the requirements for its use on soil without restrictions. Related to parasitological removal, the best helminth egg removals were obtained also using these two processes. Ascaris sp. densities in raw sludge (309-430 eggs/g) were reduced to a final density of 3-14 eggs/g in the aerobic composting process and to 4-18 eggs/g in the lime stabilized sludge. Removal is not high enough to reach the recommended level for unrestricted use of stabilized sludge.

Assessment and Use of Indicator Bacteria to Determine Sources of Pollution to an Urban River

Elevated levels of indicator bacteria within a river system represent a significant impairment to surface water quality in many urban areas within the Great Lakes watershed. Outfalls from combined sewer systems are assumed to be the major source of bacteria to streams in many of these urban areas, including the Rouge River of southeastern Michigan. Current remediation strategies largely disregard other potential sources, including water entering the river from its headwaters region, rural runoff, and contaminated groundwater. These other potential sources of bacterial pollution to the Rouge River were assessed and compared with bacteria contributed from combined sewer outfalls (CSOs). Fecal coliform (FC) and fecal streptococci (FS) densities were determined at 28 locations in the Rouge River Watershed during the spring and summer of 1997, 1998, and 1999. The mean levels of both indicator groups vary considerably along each branch of the river and show no correlation to CSO locations. The magnitude of both FC and FS levels are, in fact, frequently greater at sites upstream of the part of the river influenced by discharges from CSOs. The highest FC levels coincided with rainfall events, but FC levels at various sites along each branch of the Rouge River violated acceptable water quality standards (200 colonies/100 mL) at nearly 50% of the sites even during dry weather. Total suspended solids were moderately correlated with FC (r = 0.79) throughout the watershed, suggesting that solids may play a role in transporting bacteria into the Rouge River. The data depict a strong influence of upstream water and rural runoff on the water quality of the Rouge River. FC to FS ratios (FC/FS) suggest the primary source of bacteria throughout the watershed is from domesticated animals and wildlife and not from sewage derived from CSOs.

Aerobic thermophilic and anaerobic mesophilic treatment of swine waste

Laboratory experiments were conducted to investigate two-stage aerobic thermophilic and anaerobic mesophilic treatment of swine waste. The two-stage system included a 1-day sludge retention time (SRT) aerobic thermophilic reactor operating at 62°C and with 1.0 mg dissolved oxygen/l, followed by a 5, 9, and 14-day SRT anaerobic mesophilic digester operating at 37°C. A single stage anaerobic mesophilic digester operating at 6, 10, and 15-day SRT and 37°C was used as the control. Feed swine waste slurry average composition included total solids (TS)=4.3%; volatile solids (VS)=67% of TS; supernatant chemical oxygen demand (COD)=14,330 mg/l; fecal coliform density=7.2×10 8 MPN/g TS; pH=7.1; and alkalinity=2700 mg CaCO 3/l. Two-stage system operating at 6, 10, and 15-day system SRT reduced VS by 46, 54, and 61%, respectively, and was significantly better than the control at each SRT. Supernatant COD reduction by the two-stage system (56–67%) was significantly better than that obtained in the control (44–60%). Fecal coliform density was reduced to <10 3 MPN/g TS at all SRT by the two-stage system, whereas, the control did not reduce the fecal coliform density below 10 5 MPN/g TS at all SRT. The two-stage system anaerobic digester produced 0.56–0.64 m 3 CH 4/kg VS destroyed compared to lower levels of 0.47–0.51 m 3 CH 4/kg VS destroyed by the control, both operating at 6, 10, and 15-day system SRT. The methane gas production by the two-stage system of 0.26, 0.32, and 0.39 m 3/kg VS fed at 6, 10, and 15-day system SRT, respectively, was significantly higher than that by the control system (0.17, 0.22, and 0.25 m 3/kg VS fed at 6, 10, and 15-day SRT, respectively). The biogas produced by the two-stage system anaerobic digester contained 353–387 ppm (v/v) H 2S content compared to 569–609 ppm (v/v) H 2S content in the biogas from the control anaerobic digester. The time-to-filter values of the product sludge from the two-stage system (245, 197, and 158 s at 6, 10, and 15-day system SRT, respectively) were about 50% lower than those of the product sludge from the control (355, 295, and 250 s at 6, 10, and 15-day system SRT, respectively), indicating better dewaterability of the two-stage system product sludge.

Analyses of Sediment Bacteria Monitoring Data from Two Deep Ocean Raw Wastewater Outfalls, Victoria, BC

The sediment bacteria densities in the vicinity of two deep ocean municipal sewage outfalls, Clover Point and Macaulay Point, have been monitored annually since 1985. Each outfall measures 0.9 m diameter and is located in water depths in excess of 60 m. Sediment bacterial densities were used to define the spatial extent of the effluent plume. Thirteen years of sediment fecal coliform density data were analysed to determine whether temporal or spatial trends existed. In general, triplicate field samples were collected at various distances (0–1600 m) from each outfall in numerous compass directions. In addition to the field triplicate data, laboratory triplicate, blank analysis and reference location data were available for assessing the accuracy and the precision of the collected data. Sediment fecal coliform densities were found to be statistically greater in magnitude and above reference densities within 280 m of the outfalls; however, the spatial patterns were not consistent for each year. This region of elevated fecal coliform densities was confined to a distance of twice the length of the diffuser from the outfall. The annual means in the east and west directions at both locations were in general different each year. At Clover Point, the annual fecal coliform densities at the sampling locations did not change in the periods before 1994 and after 1994. Macaulay Point data were similar except that there were two anomalies, namely an increase in the annual means in the period after 1994 at 400 m east, and a decrease in the period before 1994 at 1600 m east. Because of the complex dynamics of fecal coliform bacterial cells in the receiving water, the sediments and the wastewaters, as well as the imprecision of the measurements of sediment fecal coliform densities, sediment fecal coliform densities are a qualitative measurement of the effect of the discharge on the local sediment quality. Very few statistically significant spatial or temporal patterns were found in the historical monitoring data, reflecting the qualitative nature of these measurements even with an extensive quality control and quality assurance program and large data sets.

Sorbitol-fermenting bifidobacteria as indicators of diffuse human faecal pollution in estuarine watersheds.

Sorbitol fermenting bifidobacteria were evaluated as indicators of non-point source human faecal pollution to three sub-estuaries with elevated faecal coliform densities. Human-specific bifidobacteria correlated with identifiable human sanitary deficiencies in feeder streams to estuarine creeks in two of three watersheds examined, one rural and one moderately developed. Sorbitol-fermenting bifidobacteria were recovered at densities ranging from 1 to 90 colony-forming-units 100 ml-1 in 11 of 258 water samples but were undetected in sediment (n = 68) and scat from resident wildlife (deer, muskrat and raccoon, n = 20). Failure to detect sorbitol-fermenting bifidobacteria in water samples during the summer months was consistent with laboratory microcosm results showing non-recoverability of Bifidobacterium adolescentis after 5-9 d in membrane-filtered estuarine water at 23 and 30 degrees C, but persistence for 4 weeks at 10 degrees C. Persistence of sewage-derived bifidobacteria in membrane-filtered freshwater at 15 degrees C was also observed. Recovery of sorbitol-fermenting bifidobacteria was complicated by high background levels of Gram-positive rods and cocci. Use of propionic acid and reduced pH (pH = 5.0), or use of a two-step resuscitation protocol using non-selective and selective media, did not improve recovery. Although human specific bifidobacteria hold promise as indicators of diffuse faecal contamination, methodological constraints now limit its application to situations of gross contamination, or sampling potential sources during environmental conditions conducive to bifid persistence.

Temperature and SRT Effects on Aerobic Thermophilic Sludge Treatment

Laboratory-scale experiments were conducted to determine optimum sludge residence time (SRT) and temperature of aerobic thermophilic pretreatment (ATP) of mixed sludge (thickened waste activated sludge and primary sludge)to achieve maximum pathogen reduction and the best process performance. 4-L laboratory-scale ATP reactors were operated at SRTs of 0.6, 1.0, and 1.5 days and temperatures of 55, 58, 62, and 65°C. ATP at temperatures ≥62°C and SRT≥ 0.6 day reduced the feed sludge fecal coliform density from 10\u7 MPN/g total solids (TS) to < 10\u4 MPN/g TS. \ISalmonella\N in the feed sludge was reduced to <1 MPN/4 g TS from 2 to 18 MPN/4 g TS by ATP at temperatures ≥ 55°C and SRT ≥ 0.6 day. ATP was able to increase sludge volatile acids concentration by 100–200% over the feed sludge volatile acid concentration and to reduce sludge supernatant chemical oxygen demand from 20,000 to 22,000 mg/L in the feed to 13,000 – 17,000 mg/L in the ATP reactor. Volatile solids reduction by ATP increased from 25 to 40% when SRT was increased from 0.6 to 1.5 days, and a 5% increase in volatile solids reduction was seen at SRTs of 0.6, 1.0, and 1.5 days when ATP temperature was increased from 55 to 65°C.

AGRICULTURAL LAND USE IMPACTS ON BACTERIAL WATER QUALITY IN A KARST GROUNDWATER AQUIFER1

ABSTRACT: The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian Region. Karst areas comprise about 18 percent of the Region's land area. An estimated one‐third of the Region's farms, cattle, and agricultural market value are on karst terrain. The purpose of this study was to compare fecal bacteria densities in karst groundwater impacted by two primary agricultural land uses in central Appalachia. Fecal bacteria densities were measured in cave streams draining two primary land management areas. The first area was pasture serving a beef cow‐calf operation. The second area was a dairy. Neither area had best management practices in place for controlling animal wastes. Median fecal coliform and fecal streptococcus densities were highest in cave streams draining the dairy. Median fecal coliform densities in the dairy‐impacted stream were greater than 4,000 CFU/100 ml and the median fecal coliform densities in the pasture‐impacted streams were less than 10 CFU/100 ml. Median fecal streptococcus densities in the same streams were greater than 2,000 CFU/100 ml and 32 CFU/100 nil, respectively. A second dairy, with best management practices for control of animal and milkhouse waste, did not appear to be contributing significant amounts of fecal bacteria to the karst aquifer. It was concluded that agriculture was affecting bacterial densities in the karst aquifer. New management practices specifically designed to protect karst groundwater resources may be one way to protect the groundwater resource.

Population dynamics of Aeromonas spp. in an urban river watershed.

Density of Aeromonas spp. at one site in the Buffalo River and at four sites on its upstream tributaries was followed from June 1992-June 1993. Membrane filtration counts of Aeromonas during the summer ranged between 18 and 4000 ml-1, which were one to two logs higher than faecal coliform and faecal streptococci densities. Aeromonas spp. in the Buffalo River, and faecal coliforms, faecal streptococci, and the heterotrophic plate count throughout the watershed, increased by approximately one log during summer rainstorms. However, Aeromonas spp. increased only by a factor of two during rainstorms at the upstream sites. Aeromonas spp. showed a strong positive correlation with both indicator bacteria and total suspended solids at the upstream sites during the summer but not the winter. Correlations between Aeromonas and indicator bacteria remained strong in the Buffalo River during the winter, signifying that different conditions exist in the Buffalo River and its upstream tributaries. The strong correlation between Aeromonas spp. and indicator bacteria in the Buffalo River suggest that, in the absence of media capable of the quantitative recovery of potentially pathogenic aeromonads, standard faecal coliform analyses may adequately assess public health risks from Aeromonas spp. in an urban river used for recreational purposes.

Aerobic thermophilic pretreatment of mixed sludge for pathogen reduction and Nocardia control

Pilot scale experiments have been conducted to investigate the use of aerobic thermophilic pretreatment (ATP) of mixed (waste activated and primary) sludge before mesophilic anaerobic digestion to meet Class A sludge pathogen control requirements. The ability of ATP to control Nocardia present in the waste activated sludge, and hence prevent foaming in the subsequent anaerobic digestion, was also investigated. Aerobic thermophilic pretreatment of mixed sludge before anaerobic digestion was able to produce sludge that can meet the following Class A pathogen reduction requirements: fecal coliform density &lt;1 000 MPN/g total solids or Salmonella sp. density &lt;3 MPN/4 g total solids; time and temperature requirements (1.8 hr at 63°C); enteric virus density &lt;1 PFU/4 g total solids; and vector attraction requirement (&gt;38% volatile solids reduction). ATP was able to control Nocardia to below detectable levels, whereas the Nocardia levels in the control anaerobic digester were ≥105 intersections/g VSS when both were fed mixed sludge containing Nocardia filament counts in excess of 105 intersections/g VSS. The ATP system was also able to produce higher volatile solids (VS) reduction, higher methane content in sludge gas, and lower sludge supernatant COD when compared with those achieved in the control anaerobic digester.

Environmental variables and their association with faecal coliform and faecal streptococci densities at thirteen Sydney beaches

Environmental variables and their association with faecal coliform and streptococci densities were investigated at a number of Sydney's metropolitan beaches. High variability in faecal coliform and faecal streptococci densities was observed at most beaches. The ability of the various models to explain the observed variation in faecal coliform or streptococci levels was relatively low, although they did provide an insight into the more influential environmental factors involved. Rainfall has the single most important effect on faecal coliform and streptococci densities at Sydney beaches. Whether this is due to increased stormwater runoff at the beaches, increased discharge through the outfalls (both the deepwater ocean outfalls and the few remaining shoreline outfalls), or a combination of both is unclear and is likely to depend on the individual beach being considered. Elevated levels of faecal coliforms and streptococci are still occasionally observed at some beaches, but these levels are usually not as high nor as frequent as they were prior to commissioning of the deepwater outfalls. The significant associations of current and plume entrapment with faecal coliform and streptococci densities at some Sydney beaches suggest that under certain conditions, effluent from the deepwater ocean outfalls can still influence faecal coliform and streptococci densities at these beaches.

Levels and Sources of Indicator Bacteria Associated with the Buffalo River “Area of Concern,” Buffalo, New York

Elevated levels of indicator bacteria within an Area of Concern (AOC) are recognized by the International Joint Commission as a water quality impairment. Combined sewer overflows are assumed to be the major source of bacteria to the Buffalo River AOC and current remediation strategies largely disregard other potential sources, including waters entering the river from the upper watershed. To assess the influence of upstream sources on pollution indicator bacteria levels in the Buffalo River, fecal coliform (FC) and fecal streptococci (FS) densities were determined at 12 sites in the Buffalo River watershed during 1992–1993. FC and FS densities were highly correlated throughout the year (r = > 0.83) and the mean levels of both indicator groups increased at sites closer to the Buffalo River. The highest levels of indicator bacteria in the water column coincided with rainfall events but FC levels violated New York State water quality standards at the three sites closest to the Buffalo River in 79% of all samples. Total suspended solids were strongly correlated with FC (r = 0.86) in the upper watershed during the summer months when flow velocities were greatest, and solids may play an important role in transporting bacteria into the Buffalo River. The fluctuations and relative magnitude of indicator bacteria levels were similar in the Buffalo River and at the upstream sites in the absence of combined sewer overflow events. The data depict a strong influence of upstream waters on the Buffalo River AOC. Upstream tributaries may make important contributions to the pollutant loading in AOCs and should not be overlooked in remediation planning.

Planning Level Evaluation of Densities and Sources of Indicator Bacteria in a Mixed Land Use Watershed

The lower Buffalo River, NY, is environmentally impaired and the 38 combined sewer outfalls within this reach historically were believed to be the primary source of bacterial contamination. A planning level evaluation of bacteria contamination was done through sample testing and compilation of existing source data, in part, with the aid of GIS technology. The intent of such evaluation is to provide an overview of the magnitude and sources of the water quality problem without extensive resource commitments, as a first step in developing remediation strategies. Testing for fecal coliform and fecal streptococci was done at 12 sites within the watershed for one year, 1992–93. Indicator bacteria densities at all sites generally were high and the state guideline for primary contact (200 fecal coliform 100 ml−1) was exceeded in 69% of 277 samples. Bacteria densities were greatest during storm events, suggesting runoff as an important source pathway. Mean fecal coliform densities significantly increased downstrea...

Inactivation of bacterial and viral indicators in secondary sewage effluents, using chlorine and ozone

The inactivation rates of indigenous populations of fecal coliforms, enterococci, Clostridium perfringens, male-specific bacteriophage and somatic coliphage in secondary sewage effluents were compared using chlorine and ozone as disinfecting agents. The fecal coliform indicator was evaluated for its reliability to index viral responses to chlorine and ozone treatments in fecally polluted effluents. Effluents were collected from several wastewater treatment plants during a variety of meteorological conditions and exhibited a wide range in quality. In chlorinated effluent, a greater than 100-fold reduction in both fecal coliform and enterococci densities was observed. However, densities of the two bacteriophage groups were generally reduced less than 10-fold. In contrast, ozone treatments resulted in the inactivation of bacterial viruses, with more than 100-fold reductions of male-specific and somatic bacteriophage densities. The elimination of vegetative bacteria was less dramatic in ozonated effluents with less than a 30-fold reduction in the densities of both of these indicators. C. perfringens was relatively insensitive to inactivation by either disinfectant; populations of this indicator were stable for prolonged contact periods. These findings demonstrate that the fecal coliform indicator is inadequate for predicting viral responses to chlorine or ozone treatments. Ozone contact time and residual concentrations were increased appreciably in later trials to further determine the sensitivities of fecal coliforms and enterococci to this treatment. However, increasing these parameters, alone or in concert, did not enhance the rates at which vegetative bacterial populations declined.

Agricultural Impacts on Bacterial Water Quality in Karst Groundwater

AbstractA 2‐yr study (1991–1992) was conducted in a karst region in southeast West Virginia to determine the impact of agriculture on groundwater quality. The primary agriculture is characterized by seasonal cattle grazing. Fecal coliform densities were measured weekly in the resurgences of three karst basins possessing different degrees of agricultural intensity (79, 51, and 16% land use in agriculture). Fecal coliforms were also measured in a creek at sites upstream and downstream of the known resurgences from the most agriculturally intensive (79%) basin. The fecal coliform densities in the resurgences peaked in the summer and declined in the fall, with a recovery in late winter before the introduction of new cattle. The timing of the recovery indicated that significant storage of fecal material had taken place, which was transported to the groundwater when soil water conditions permitted. For most of each year, soil water effects appeared to have a greater bearing on the fecal coliform densities than did the presence or absence of cattle. The data did not generally support a strong relationship with percent land use in agriculture. This was attributed to the high variability in the data and to low soil moisture during periods of recession that inhibited the transport of fecal material to the groundwater. The karst resurgence springs of the most intensively agricultural basin were contaminated with fecal bacteria. Fecal bacteria concentrations were observed to significantly increase, in the receiving surface stream, from a point upstream of the resurgence springs to a point downstream of the resurgence springs.

Assessment of the Bacteriological Quality of Compost from a Yard Waste Processing Facility

Citizen concern over possible pathogenic microorganism contamination in compost and in a runoff collection pond prompted a U.S. Environmental Protection Agency (EPA) investigation. One out of eight samples collected from the distribution pile at a yard waste compost processing facility in Knoxville, Tennessee, was found to have 2.3 × 103 MPN/g fecal coliform, no Escherichia coli (E. coli) were detected. All other distribution pile samples proved to be negative for fecal coliform. The geometric mean of the eight samples was found to be less than 38 MPN/g, well below the 1,000 MPN/g limit for land application of class A municipal sludges treated by an acceptable composting process. Samples obtained from the processing pile area before and after shredding had an average fecal coliform density of greater than 5.0 × 105 MPNig, and an average E. coli density of 6.0 × 104 or 7.4 × 104 MPN/g depending upon the analytical technique used. The origin of these microorganisms was not determined, though it appears unli...