Number Of Fecal Coliforms Research Articles

Effects of Several Applications of Digested Sewage Sludge on Soil and Plants

Sewage sludge production has significantly increased during the last years in European Union (EU) countries, being primarily used for agricultural purposes. In this study, digested sewage sludge was applied to greenhouse soil over a three-year period (2001–2003), with three sludge treatments in the first two years (2, 4, and 6 kg m−2) and three more applications using a greater quantity in the last year (6, 8, and 10 kg m−2). The effects of sewage sludge application on soil and on a leafy crop (Lactuca sativa L.) were studied. Mineral elements, organic matter, pH, and heavy metals were measured in soil and plant tissues. Pathogen and indicator microorganism dynamics in soil were also determined after each sludge application. Results showed that sewage sludge applications increased organic matter, P, and N Ca content in soil. Furthermore, Zn, Pb, Ni, and Cu content increased in soils, primarily after high doses of sludge. The highest yield value was obtained in the second-year harvest, since the last sludge application did not increase yield. Fecal coliform numbers decreased significantly one month after sludge application. However, total coliforms, Clostridium sulphite-reducers and Salmonella, were present in soils three months after sludge application.

OPTIMIZATION OF WINDROW FOOD WASTE COMPOSTING TO INACTIVATE PATHOGENIC MICROORGANISMS

Composting is a popular means of treating organic wastes, and properly controlled composting can destroy thepathogenic microorganisms present in wastes for a human- and environment-friendly end product. Therefore, optimizationof windrow composting of food waste, manure, and bulking agents was evaluated for maximum pathogen inactivation(Salmonella and E. coli O157:H7). Seasonal effects on reductions of Salmonella and E. coli O157:H7 according to thecompost temperatures were studied (90 to 150 days). Fecal coliforms and fecal streptococcus were also monitored duringcomposting. The most probable number (MPN) method was used for enumerating both indicator and pathogenicmicroorganisms. The results of this study indicated that seasonal differences caused significant effects on the peaktemperatures and the duration of high thermophilic temperatures (>55C) of windrows. Winter conditions resulted ininconsistent inactivation of pathogenic microorganisms including regrowth to high values during several time intervals. Thereduction levels of Salmonella spp. and E. coli O157:H7 ranged from initial ranges of 377-483 MPN/g to final ranges of6-150 MPN/g in winter, and to <0.3 MPN/g in summer. It was also observed that summer composting resulted in a bettercorrelation (r2 > 0.90) between the number of fecal coliforms and the pathogenic microorganisms (Salmonella spp. andE. coli O157:H7). Fecal streptococcus was only slightly reduced in the majority of the trials from 377-483 MPN/g to221-514 MPN/g in winter and from 365-460 MPN/g to a range of 11-265 MPN/g in summer. Extreme Vertices Mixture Design(EVMD) analysis suggested an optimum mixture as: 43.3% food waste, 28.3% manure, and 28.3% bulking agents. Theperformance of the optimum mixture has been validated, achieving a high level of inactivation of pathogens similar to thatwith previous trials, with good correlations of fecal coliforms to the pathogens of interest, but with a high resistance of fecalstreptococcus to inactivation. It was concluded that the EVMD design was successful in optimizing mixture components forwindrow composting in order to achieve maximum pathogen reduction.

COMPARISON OF ODOROUS VOLATILE COMPOUNDS FROM FOURTEEN DIFFERENT COMMERCIAL COMPOSTS USING SOLID-PHASE MICROEXTRACTION

In this study, odorous volatile compounds (OVCs) from market-ready, commercial composts supplied by14 different producers were compared using a recently developed method involving solid-phase microextraction (SPME) ofheadspace volatiles followed by GC analysis. The products analyzed were derived from a cross-section of the wide array ofcompost feedstock ingredients used in the U.S. (e.g., biosolids, yard trimmings, animal manure, and industrial by-products).A variety of quality assessment tests were performed using test procedures specified in a national certification program offeredthrough the U.S. Composting Council. Measurements of odorous chemicals (i.e., trimethylamine, carbon disulfide,dimethylsulfide, dimethyldisulfide, propionic acid, and butyric acid) supplemented other quality aspects in the evaluation ofstability. Result showed that relatively higher concentrations of reduced sulfur-containing compounds were detected frommarketable composts containing sewage sludge than from composts produced with other feedstocks. The greatest amountsof reduced sulfur-containing compounds were detected from a compost containing a mixture of industrial sludge andagricultural byproducts. Pathogen indicator microbes for most composts were within limits for Class A (U.S. EPA 40CFRPart503). Very large numbers of fecal coliforms, E. coli, and Enterococcus were present in the compost that produced thegreatest concentrations of carbon disulfide and dimethylsulfide. Composts containing sewage sludge and yard wastesproduced relatively higher concentrations of propionic and butyric acids than those containing other ingredients. Thecomposition of OVCs in compost products can be objectively evaluated with the SPME method reported here. Results incombination with other compost quality factors may help compost producers improve product quality.

Microbial quality of tilapia reared in fecal-contaminated ponds*1

The microbial quality of tilapia reared in four fecal-contaminated fishponds was investigated. One of the fishponds (TDP) received treated sewage with an average fecal coliform count of 4×103 cfu/100 mL, and feed of fresh duckweed grown on treated sewage was used. The number of fecal coliform bacteria attached to duckweed biomass ranged between 4.1×102 and 1.6×104 cfu/g fresh weight. The second fishpond (TWP) received treated sewage, and the feed used was wheat bran. The third fishpond (FDP) received freshwater, and the feed used was the same duckweed. Pond 4 (SSP) received only settled sewage with an average fecal coliform count of 2.1×108/100 mL. The average counts in the fishponds were 2.2×103, 1.7×103, 1.7×102, and 9.4×103 cfu/100 mL in TDP, TWP, FDP, and SSP, respectively. FDP had a significantly (P<0.05) lower fecal coliform count than the treated sewage-fed ponds and SSP. The microbial quality of the tilapia indicated that all tissue samples except muscle tissues were contaminated with fecal coliform. Ranking of the fecal coliform contamination levels showed a decrease in the order intestine>gills>skin>liver. Poor water quality (ammonia and nitrite) in SSP resulted in statistically higher fecal coliform numbers in fish organs of about 1 log10 than in treatments with good water quality. Pretreatment of sewage is therefore recommended.

N and P leaching and microbial contamination from intensively managed pasture and cut sward on sandy soil in Finland

The aim of this study was to find out if nutrient leaching from grassland represents a threat to groundwater in areas that are subject to freezing and extensive snow cover. The effects of grazing and cutting on groundwater quality were compared using field lysimeters during a 3-year experiment at North Savo Research Station (63°10′N, 27°18′E), Finland. One-third of the annual precipitation at this site (578 mm per year) falls as snow. Snowmelt produces over 100 mm of water flow and there is a substantial risk of nutrient leaching. The soil at the site was a medium textured Dystric Regosol , consisting mainly of fine sand. The lysimeters used in this study were 100 m 2 and 1.8 m deep, suitable for grazing studies. The watering point for cows was located on one of the lysimeters. The area was fertilized with N at 220 kg ha −1 per year. After two summers of grazing and cutting the area was treated with glyphosate and in the following spring it was ploughed and resown to grass. The NO 3 -N concentrations were low and there were no differences among treatments during the first 2 years of the trial. After glyphosate application nitrate leaching increased and the average concentrations of NO 3 -N from cut, grazed and watering point lysimeters were 3.4, 10.2 and 21.8 mg l −1 , respectively. The amounts of leached NO 3 -N after glyphosate treatment were 10, 43 and 139 kg ha −1 per year, respectively. Phosphorus leaching was negligible. In the first year the numbers of heterotrophic micro-organisms in leachate from grazed and cut lysimeters were similar. In the second year leachate from grazed lysimeters contained more heterotrophic micro-organisms than that from cut plots (geometric means 44 000 and 4600 CFU ml −1 , respectively). Moreover, the leachate from the grazed plots and the watering point occasionally contained low numbers of enteric micro-organisms, faecal coliforms and tyrobutyricum clostridia . The study indicated that cutting and grazing did not represent a risk to groundwater quality during grass cover years, but renovation of pasture caused a significant N leaching to groundwater.

Microbial quality of tilapia reared in fecal-contaminated ponds

The microbial quality of tilapia reared in four fecal-contaminated fishponds was investigated. One of the fishponds (TDP) received treated sewage with an average fecal coliform count of 4×10 3 cfu/100 mL, and feed of fresh duckweed grown on treated sewage was used. The number of fecal coliform bacteria attached to duckweed biomass ranged between 4.1×10 2 and 1.6×10 4 cfu/g fresh weight. The second fishpond (TWP) received treated sewage, and the feed used was wheat bran. The third fishpond (FDP) received freshwater, and the feed used was the same duckweed. Pond 4 (SSP) received only settled sewage with an average fecal coliform count of 2.1×10 8/100 mL. The average counts in the fishponds were 2.2×10 3, 1.7×10 3, 1.7×10 2, and 9.4×10 3 cfu/100 mL in TDP, TWP, FDP, and SSP, respectively. FDP had a significantly ( P<0.05) lower fecal coliform count than the treated sewage-fed ponds and SSP. The microbial quality of the tilapia indicated that all tissue samples except muscle tissues were contaminated with fecal coliform. Ranking of the fecal coliform contamination levels showed a decrease in the order intestine>gills>skin>liver. Poor water quality (ammonia and nitrite) in SSP resulted in statistically higher fecal coliform numbers in fish organs of about 1 log 10 than in treatments with good water quality. Pretreatment of sewage is therefore recommended.

Microbial contamination and chemical toxicity of the Rio Grande

BackgroundThe Rio Grande River is the natural boundary between U.S. and Mexico from El Paso, TX to Brownsville, TX. and is one of the major water resources of the area. Agriculture, farming, maquiladora industry, domestic activities, as well as differences in disposal regulations and enforcement increase the contamination potential of water supplies along the border region. Therefore, continuous and accurate assessment of the quality of water supplies is of paramount importance. The objectives of this study were to monitor water quality of the Rio Grande and to determine if any correlations exist between fecal coliforms, E. coli, chemical toxicity as determined by Botsford's assay, H. pylori presence, and environmental parameters. Seven sites along a 112-Km segment of the Rio Grande from Sunland Park, NM to Fort Hancock, TX were sampled on a monthly basis between January 2000 and December 2002.ResultsThe results showed great variability in the number of fecal coliforms, and E. coli on a month-to-month basis. Fecal coliforms ranged between 0–106 CFU/100 ml while E. coli ranged between 6 to > 2419 MPN. H. pylori showed positive detection for all the sites at different times. Toxicity ranged between 0 to 94% of inhibition capacity (IC). Since values above 50% are considered to be toxic, most of the sites displayed significant chemical toxicity at different times of the year. No significant correlations were observed between microbial indicators and chemical toxicity.ConclusionThe results of the present study indicate that the 112-Km segment of the Rio Grande river from Sunland Park, NM to Fort Hancock, TX exceeds the standards for contact recreation water on a continuous basis. In addition, the presence of chemical toxicity in most sites along the 112-Km segment indicates that water quality is an area of concern for the bi-national region. The presence of H. pylori adds to the potential health hazards of the Rio Grande. Since no significant correlation was observed between the presence of H. pylori antigens and the two indicators of fecal contamination, we can conclude that fecal indicators cannot be used to detect the presence of H. pylori reliably in surface water.

Identification of sources of Escherichia coli in South Carolina estuaries using antibiotic resistance analysis

Fecal pollution from nonhuman (pets, livestock or wildlife) and human sources is often one of the major factors associated with urbanization that contribute to the degradation of water quality. Methods to differentiate animal from human sources of fecal coliform contamination could assist resource managers in developing strategies to protect shellfish harvesting areas and recreational waters. In this study, surface water samples were collected from both a developed and an undeveloped watershed in coastal South Carolina. Influent and effluent samples from several wastewater treatment plants (WWTPs) in the same area were also collected. Most Probable Numbers (MPNs) of fecal coliforms were determined for all samples. Escherichia coli isolates were analyzed for antibiotic resistance (AR) to 10 antibiotics. Then, AR indices (no. of resistant/total no. of antibiotics tested), were calculated for each isolate and site. Results indicated that MPNs from the WWTP samples were significantly higher than those from the developed watershed which were significantly higher than those from the undeveloped watershed ( p<0.0001). The AR analyses suggested that there was a trend toward increased antibiotic resistance in samples for the urbanized Broad Creek (BC) watershed. In the Okatee River (OR), E. coli isolates from three sites (20%) showed resistance to a single antibiotic (penicillin) but in BC, isolates from seven sites (47%) were resistant to multiple antibiotics, and the predominant resistance pattern was chlortetracycline–oxytetracycline–tetracycline. Raw sewage isolates from most WWTPs contained E. coli that exhibited resistance to multiple antibiotics. Cluster analysis indicated that all resistant OR sites had antibiotic resistant isolates that matched AR patterns found in isolates from WWTPs. Similarly, six of the seven sites in BC had AR patterns that matched with resistance patterns in WWTPs. These results suggest that AR testing may be a useful tool for differentiating E. coli from human and wildlife sources. Further testing of bacterial isolates from known animal sources is necessary to better assess the utility of this approach.

Improved wastewater disinfection by ultrasonic pre-treatment

The objective of our work is to evaluate the scientific and economic potential of US application as a pre-treatment step in combination with UV to optimise the disinfection process of wastewaters. Ultrasound application of 20 s at low density of 30 W/l changed the particle size distribution (PSD) of the samples, the mean particle diameter dropped from 70 to 11 μm. Generally it is assumed that bioparticles bigger than 50 μm are difficult to disinfect by UV. We observed that the relevant particle size range >50 μm in samples taken from the primary clarifier was reduced by at least three-quarters by low ultrasound doses. As expected, these changes in PSD notably effect the disinfection efficiency of UV. Whereas UV treatment of secondary clarifier's effluents alone led to a reduction of fecal coliforms by 2.5 log units, pre-treatment by sonication (only 5 s at densities of 50 and 310 W/l) clearly enhanced the disinfection efficiency: reductions of CFU (colony forming unit) concentration now ranged between 3.3 and 3.7 log units. We noticed an influence of the bacteria's morphology on the disinfection efficiency of the combined process (US plus UV). Gram-positive streptococci seem less vulnerable to ultrasound exposure than thinner-walled gram-negative bacteria like the entire group of coliforms. The application of an ultrasound step might be also useful in terms of cost-effectiveness. In our lab-scale tests 30 s of UV treatment alone were required to reduce the number of fecal coliforms by 3.7 log units. When applied in combination, 5 s of ultrasonic followed by only 5 s of UV irradiation had the same result and energy consumption was only 43%.

Effects of bacterial direct-fed microbials and yeast on site and extent of digestion, blood chemistry, and subclinical ruminal acidosis in feedlot cattle.

Two studies were conducted to determine whether a bacterial direct-fed microbial (DFM) alone or with yeast could minimize the risk of acidosis and improve feed utilization in feedlot cattle receiving high-concentrate diets. Eight ruminally cannulated steers, previously adapted to a high-concentrate diet, were used in crossover designs to study the effects of DFM on feed intake, ruminal pH, ruminal fermentation, blood characteristics, site and extent of digestion, and microbial protein synthesis. Steers were provided ad libitum access to a diet containing steam-rolled barley, barley silage, and a protein-mineral supplement (87, 8, and 5% on a DM basis, respectively). In Exp. 1, treatments were control vs. the lactic-acid producing bacterium Enterococcus faecium EF212 (EF; 6 x 10(9) cfu/d). In Exp. 2, treatments were control vs EF (6 x 10(9) cfu/d) and yeast (Saccharomyces cerevisiae; 6 x 10(9) cfu/d). Supplementing feedlot cattle diets with EF in Exp. 1 increased (P < 0.05) propionate and (P < 0.05) decreased butyrate concentrations, decreased the nadir of ruminal pH (P < 0.05), enhanced the flow of feed N (P < 0.10) to the duodenum but reduced that of microbial N (P < 0.10), reduced (P < 0.10) intestinal digestion of NDF, and increased (P < 0.10) fecal coliform numbers. Other than the increase in propionate concentrations that signify an increase in energy precursors for growth, the other metabolic changes were generally considered to be undesirable. In Exp. 2, providing EF together with yeast abolished most of these undesirable effects. Combining EF with yeast increased the DM digestion of corn grain incubated in sacco, but there were no effects on altering the site or extent of nutrient digestion. The diets used in this study were highly fermentable, and the incidence of subclinical ruminal acidosis, defined as steers with ruminal pH below 5.5 for prolonged periods of time, was high. Supplementing the diet with EF, with or without yeast, had limited effects on reducing ruminal acidosis. It seems that cattle adapted to high-grain diets are able to maintain relatively high feed intake and high fiber digestion despite low ruminal pH. The Enterococcus faecium bacterium and yeast used in this study were of limited value for feedlot cattle already adapted to high-grain diets.

Faecal coliforms in pond water, sediments and hybrid tilapia Oreochromis niloticus ×Oreochromis aureus in Saudi Arabia

Total bacterial load, total coliforms faecal coliforms in pond water, sediment, intestine of hybrid tilapia Oreochromis niloticus×Oreochromis aureus and pigeon Columba livia faeces were investigated monthly over a period of 1 year from July 1999 to June 2000. Fish were collected randomly by a cast net. Samples were analysed for coliforms using the multiple-tube fermentation technique. Results showed total viable bacterial counts in the pond water, sediment, intestine of tilapia and pigeon faeces ranging from 1.8±0.9×102 to 6.0±1.2×104 cfu mL−1, 3.2±1.2×105 to 2.8±1.5×107 cfu g−1, 8.2±1.6×105 to 9.9±1.5×107 cfu g−11.0±0.4×107to9.7±0.2×109 cfu g−1respectively. The most probable number (MPN) of coliforms and faecal coliforms ranged from 287±12 to ≥1600±0 100 mL−1 in pond water; the MPN ranges for sediment, tilapia intestine and pigeon faeces were 257±29 to ≥1100±0 g−1, 237±46 to ≥1100±0 g−1 and 403±98 to ≥1100±0 g−1 respectively. The abundance of normal bacteria coliforms was greater in the warm months than in the cold months. Ground water was free from any sort of coliform organisms, and there were no sources of human faecal matter in the pond. So, it is clear that faecal coliforms from pigeon faeces significantly contaminated (P<0.05) the ponds and tilapia intestines. Escherichia coli was the only coliform organism found in pond water, sediment, intestine of tilapia and pigeon faeces.

Microbiological quality of drinking water of urban and rural communities, Brazil.

To evaluate the microbiological quality of treated and untreated water samples came from urban and rural communities and to examine the relationship between coliforms occurrence and average water temperature, and a comparison of the rainfall levels. A sample of 3,073 untreated and treated (chlorinated) water from taps (1,594), reservoir used to store treated water (1,033), spring water (96) and private well (350) collected for routine testing between 1996 and 1999 was analyzed by the multiple dilution tube methods used to detect the most probable number of total and fecal coliforms. These samples were obtained in the region of Maring , state of Paran , Brazil. The highest numbers water samples contaminated by TC (83%) and FC (48%) were found in the untreated water. TC and FC in samples taken from reservoirs used to store treated water was higher than that from taps midway along distribution lines. Among the treated water samples examined, coliform bacteria were found in 171 of the 1,033 sampling reservoirs. Insufficient treatment or regrowth is suggested by the observation that more than 17% of these treated potable water contained coliform. TC and FC positive samples appear to be similar and seasonally influenced in treated water. Two different periods must be considered for the occurrence of both TC and FC positive samples: (i) a warm-weather period (September-March) with high percentage of contaminated samples; and (ii) cold-weather period (April-August) were they are lower. Both TC and TF positive samples declined with the decreased of water temperature.

The stormwater drain system as a pollution vector of the seashore in Fortaleza (Ceará State, Brazil)

The aim of this study was to make a diagnosis of coastal pollution through bacteriological analysis of water taken from stormwater drain systems and the nearby seashore. The results were submitted to statistical analysis as to differences in the Most Probable Number (MPN) of fecal coliform (FC) found between the stormwater drain systems and adjacent seashore locations both at low and high tides. The main conclusions were: (a) most water samples collected from the stormwater systems presented MPN values for FC above 1,000 per 100 ml; (b) only 20% of the samples from the adjacent seashore presented MPN values for FC above 1,000 per 100 ml, a fact which may be explained by the distance between the drain system outlets and the actual seashore; (c) FC/100 ml values were invariably higher in the stormwater drain systems than in seawater; (d) out of the 180 strains isolated, 118 were Escherichia coli; (e) the highest in-sewer pollution rate was found at the sampling location in front of Imperial Othon Palace Hotel (IO-SEW), characterized by the presence of an everlasting puddle, while the most polluted seawater sample was taken in front of Statue of Iracema (SI-SEA); (g) the high tide regime enhances the chance of pollution of the coastal zone by fecal coliforms; (h) the high pollution indices by fecal coliforms can only be accounted for by the existence of illegal sewage pipelines connected to the stormwater drain systems.

Enumeration of Coliform Bacteria in Wastewater Solids Using Defined Substrate Technology

Commercially available defined substrate technology for the enumeration of coliform bacteria was investigated for its applicability to waste activated sludge (WAS) solids. The defined substrate, Colilert, in conjunction with the QuantiTray enumeration system, was compared with multiple-tube fermentation (MTF). Multiple-tube fermentation analyses (U.S. Environmental Protection Agency [U.S. EPA]-accepted methods for the enumeration of coliforms in wastewater solids) were conducted on settled wastewater solids using lauryl tryptose broth as the presumptive phase and brilliant-green lactose bile broth for the confirmed phase of total coliform enumeration. Both EC medium for fecal coliform identification and EC-4-methyl-umbelliferyl-beta-D-glucuronide (MUG) media for Escherichia coli for the MTF completed phase were also conducted on the WAS. Samples analyzed included raw WAS and WAS that had been pasteurized at 70 degrees C for 15 and 30 minutes, respectively. Twenty replicates of each sample were measured to demonstrate statistical equivalence of the total coliform numbers for all three WAS samples (raw, 15-minute pasteurization, and 30-minute pasteurization). Results show that both systems provided statistically equal total coliform most probable numbers (MPNs) for all samples tested. As expected, fecal coliform numbers identified by the MTF technique were statistically higher than E. coli enumerated by Colilert-QuantiTray. However, the E. coli MPN generated by the MTF method was found to be statistically equal to the Colilert-QuantiTray numbers. Because of its ease of use and reduced time to obtain the analysis, the Colilert-QuantiTray system can be useful in enumerating coliforms in WAS. However, more data are required to definitively show equivalence of the commercially available defined substrate technology to the U.S.-EPA accepted protocol. It is hoped that the results of this study will help form a database for the acceptance of the Colilert-QuantiTray system for WAS bacterial analyses.

Elimination of enteric bacteria in biological–chemical wastewater treatment and tertiary filtration units

The occurrence and removal of salmonellae and faecal indicators in four conventional municipal wastewater treatment plants (MWTP) were investigated. In addition, we tested the efficiency of a semi-technical scale biological nutrient removal process and three pilot-scale tertiary filtration units in microbial removal. All influent samples collected from MWTPs contained salmonellae from 93 to 11 000 MPN/100 ml and indicator bacteria from about 10 7 to 10 8 CFU/100 ml. The reductions in salmonella numbers achieved in full-scale biological–chemical wastewater treatment and semi-technical scale biological nutrient removal processes were usually between 94% and virtually 100% (99.9%) and indicator bacteria reductions between 2 and 3 log units. Microbial numbers in MWTP effluents could be modelled as a function of effluent residual organic matter, suspended solids and total phosphorus concentrations. Pilot-scale tertiary treatment by rapid sand contact filter, chemical contact filter and biological–chemical contact filter reduced salmonella numbers below the detection limit and faecal coliform numbers on average by 99%, 39% and 71%, respectively. A total of 32 Salmonella serovars were identified among 197 Salmonella isolates from municipal wastewaters. Of the isolates, 32% were resistant to nalidixic acid, indicating reduced sensitivity to ciprofloxacin, the drug of choice in the treatment of salmonellosis. In addition, 18% of the isolates were multiresistant. Our results, especially antibiotic resistant Salmonella strains, indicate that conventional municipal wastewater treatment without efficient tertiary treatment, like filtration or disinfection, may constitute a risk for public health.

The use of ultrasound and γ-irradiation as pre-treatments for the anaerobic digestion of waste activated sludge at mesophilic and thermophilic temperatures

The effect of ultrasound and γ-irradiation used as pre-treatments for the anaerobic digestion of waste activated sludge at both mesophilic and thermophilic temperatures was examined. Untreated activated sludge was also subjected to anaerobic digestion at these temperatures as a control. The sonication time was 90 s using a Soniprep 150 (MSE Scientific Instruments) which operated at 23 kHz and had been adjusted to give an output of 47 W and the γ-irradiation dose was 500 krad. The digesters were operated in a semi-continuous mode, being fed with fresh sludge every 24 h at hydraulic retention times (HRT) of 8, 10 and 12 days. Over the 24 h period the differences between the digesters, in terms of volatile solids (VS) reductions and biogas production, were not statistically significant for any particular set of conditions. Thermophilic digestion performed better than mesophilic digestion in terms of biogas production, VS reductions (except at HRT of 8 days) and specific methane yields and the optimum retention time was 10 days, at both temperatures. When gas production over the initial eight hours (probably the hydrolytic stage) was examined, it was found that the gas production rates for pre-treated sludges were higher than those for untreated sludges. This was most pronounced at thermophilic temperatures and a HRT of 10 days. Sonication did not affect the numbers of faecal coliforms in the sludge. However, γ-radiation caused a 3-log reduction and, when coupled with mesophilic digestion, gave a product which contained <100 g −1 TS. Thermophilic anaerobic digestion produced sludges which contained <1 g −1 TS irrespective of any pre-treatment.

Rapid enzymatic detection of Escherichia coli contamination in polluted river water.

The relationship between the rate of beta-D-glucuronidase hydrolysis (GLUase-HR) and the E. coli concentration in rivers differing in the extent of faecal pollution was investigated. It was hypothesized that the rate of GLUase-HR is a better surrogate parameter for E. coli concentrations than estimated numbers of faecal coliforms (FC). The GLUase-HR of the water sample filter residues was determined as the rate of cleavage of 4-methylumbelliferyl-beta-D-glucuronide. FC and E. coli concentrations were enumerated using mFC and Chromocult Coliform agar, respectively. Regression analysis revealed that a 90% variation of the variable log GLUase-HR was directly related to the variable log E. coli concentrations. The observed relationship between the log of the FC count and the log of the GLUase activity could be explained by the hydrolysis activity of the E. coli population, as E. coli is a part of the FC group. The data suggest that the log of the GLUase-HR can be used as a surrogate parameter for the log of the E. coli concentrations. GLUase-HR determination may provide a rapid alternative technique to estimate E. coli concentrations in freshwaters.

Seasonal fluctuation of bacterial indicators in coastal waters

The relationships between number of coliforms, fecal coliforms, E. coli, fecal streptococci, location, time and seasonal factors in marine environments of northwest Greece were investigated over a period of 4 years. Research focused on measuring and comparing bacteria in coastal marine waters undergoing heavy bacterial charge during the tourist season. Microbiological pollution was increased during the summer period. Seasonal fluctuation of the fecal indicator bacteria was noted and concerned mainly E. coli and fecal coliforms, which are the most sensitive indicators in the marine environment.

VARIAÇÃO DA CONCENTRAÇÃO DE BACTÉRIAS INDICADORAS DE CONTAMINAÇÃO FECAL NAS DIVERSAS FASES DO PROCESSO DE TRATAMENTO DE ÁGUA DE ABASTECIMENTO PÚBLICO DA CIDADE DE ARARAQUARA - SÃO PAULO

O abastecimento de água de qualidade e em quantidade suficiente é de fundamental importância para a saúde da população. A potabilidade bacteriológica é determinada principalmente pela verificação da presença de bactérias do grupo coliforme (totais e fecais) indicadoras de poluição fecal, maior responsável pela transmissão de doenças infecciosas à população. O objetivo desta pesquisa foi verificar a eficácia dos processos de tratamento executados nas Estações de Tratamento de Água (ETA) de Araraquara, determinando as concentrações de bactérias coliformes totais e fecais, em&#x0D; cada etapa do processo de tratamento: água bruta, após floculação/decantação, filtração e cloração - relacionadas com a turbidez, avaliando se a água produzida está de acordo com os padrões do Ministério da Saúde e do Estado de São Paulo. O número mais provável (NMP/100mL) de bactérias coliformes totais e coliformes fecais foi determinado pela técnica das fermentações em tubos múltiplos, provas presuntiva e confirmatória. As análises foram realizadas mensalmente por um período de doze meses. Em todas as&#x0D; colheitas verificou-se que a água bruta apresentou grande quantidade de coliformes (NMP/100mL), daí a necessidade de tratamento e a importância fundamental que a fase de desinfecção tem para que a água chegue a população dentro dos padrões de qualidade. Concluíu-se que após a cloração ocorreu redução no número (NMP/100mL) de bactérias&#x0D; coliformes totais e fecais paralela à redução de turbidez e que a água produzida pelas ETAs atende aos padrões determinados pelo Ministério da Saúde e do Estado de São&#x0D; Paulo.

Campylobacter spp. in waters of three main Western Pomerania water bodies

Campylobacters are responsible for increasing numbers of gastroenteritis cases in humans as well as miscarriages and diarrhea in farm and domestic animals. Surface waters are potential reservoirs and transmitting vehicles for these bacteria. Subject of analysis were surface water samples collected from the River Odra, Szczecin Lagoon and the Pomeranian Bay in monthly or bimonthly intervals, starting from April 1998. Analysis directed on campylobacters included enrichment in Preston broth prior to plating on CCDA isolation medium and identification, to the species level, by the api CAMPY tests. The detection level of the method was 1 CFU/10 ml. Numbers of total and faecal coliforms were counted according to the national standards. In addition water temperature and water saturation with oxygen were measured. Presence of Campylobacter spp., at the level detectable by the method applied, was confirmed in 19.7 % of the Odra River, 5.6 % of the Szczecin Lagoon and 0 % of the Pomeranian Bay surface water samples. The contamination level of the Campylobacter – positive surface water samples did not exceed 10 CFU/ml. Isolation frequency depended on water purity class, counts of total and faecal coliforms and sampling site (p < 0.01). Species dominating in the River Odra and Szczecin Lagoon surface waters were C. jejuni ssp. jejuni and C. coli, respectively