Ml For Faecal Coliforms Research Articles

Presence of Indicator Bacteria and Occurrence of Potentially Pathogenic Nontuberculous Mycobacteria Species in Packaged Ice Cubes in Central Mexico

This study aimed to determine the bacteriological quality and presence of diarrheagenic Escherichia coli pathotypes (DEP) and nontuberculous mycobacteria (NTM) species in 85 packaged ice samples from 12 different states of central Mexico. Three samples had a pH of 9.8 and therefore fell outside of the acceptable range for pH. All samples were positive for aerobic-mesophilic bacteria, with limits ranging from 1 to 3.47 log CFU/mL. In total, 35, 11, and 3 ice samples were positive for total coliforms (TC), fecal coliforms (FC), and E. coli, respectively. In the samples, the TC concentration ranged from <1.1 to >23 MPN/100 mL and from <1.1 to 23 MPN/100 mL for FC and E. coli. In total, 38 (44.7%) ice samples were outside of Mexico's official guidelines. None of the 12 E. coli strains isolated from the three ice samples belonged to DEP. NTM were recovered from 20 ice samples and included M. neoaurum (n = 7), M. porcinum (n = 2), M. flavescens (n = 2), M. fortuitum (n = 1), M. abscessus (n = 1), M. senegalense (n = 1), M. conceptionense (n = 1), and M. sp. (n = 1). In the remaining four samples, two NTM were isolated simultaneously. Thus, we recommend that producers should evaluate the microbiological quality of purified water used as a raw material as well as that of the final product, the ice should be packed in thick bags to avoid stretching and tearing during transportation or storage to prevent environmental contamination of ice, personnel involved in the production, and handling of ice should be trained in relative hygiene matters and how ice-machines should be cleaned and disinfected and the implementation of hazard analysis and critical control points must be applied throughout the chain of production. Finally, regular inspection by the authorities is also of great importance. These recommendations can be applied in different countries with low microbiological quality packaged ice.

Multidrug-resistant pathogens contaminate river water used in irrigation in disenfranchised communities

The contamination of fresh surface waters poses a significant burden on human health and prosperity, especially in marginalized communities with limited resources and inadequate infrastructure. Here, we performed in-depth genomic analyses of multidrug-resistant bacteria (MDR-B) isolated from Al-Oueik river water that is used for irrigation of agricultural fields in a disenfranchised area that also hosts a makeshift Syrian refugee camp. A composite freshwater sample was filtered. Faecal coliforms were counted and extended spectrum cephalosporins and/or ertapenem resistant bacteria were screened. Isolates were identified using MALDI-TOF-MS and analysed using whole-genome sequencing (WGS) to identify the resistome, sequence types, plasmid types, and virulence genes. Approximately 106 CFU/100 mL of faecal coliforms were detected in the water. Four drug-resistant Gram-negative bacteria were identified, namely Escherichia coli, Klebsiella pneumoniae, Enterobacter hormaechei, and Pseudomonas otitidis. Notably, the E. coli isolate harboured blaNDM-5 and a YRIN-inserted PBP3, representing an emerging public health challenge. The K. pneumoniae isolate carried blaSHV-187 as well as mutations in the gene encoding the OmpK37 porin. Enterobacter hormaechei and P. otitidis harboured blaACT-16 and blaPOM-1, respectively. This report provides comprehensive genomic analyses of MDR-B in irrigation water in Lebanon. Our results further support that irrigation water contaminated with faecal material can be a reservoir of important MDR-B, which can spread to adjacent agricultural fields and other water bodies, posing both public health and food safety issues. Therefore, there is an urgent need to implement effective water quality monitoring and management programs to control the proliferation of antibiotic-resistant pathogens in irrigation water in Lebanon.

Van İli Sınırları İçerisinde Van ve Erçek Gölü’nün Mikrobiyolojik Kirlilik Seviyesinin Belirlenmesi

Objective: Lake Van is one of the most important recreation areas of the region. Investigation of microbiological pollution of Lake Van is very important for public health. The aim of this study is to assess the microbiological pollution and determine water quality of the lakes Van and Erçek situated within Van Province, which are used for swimming and recreation to protect both human and environmental health. For this purpose, the presence of fecal coliform, total coliform and enterococci were investigated in samples taken from 29 different points of the lakes. Method: Between June and September 2015, 232 water samples were taken from predefined 29 points, every two weeks, and sent to the Public Health Laboratory of Van Province in 300-500 mL sterile plastic bottles in accordance with Bathing Water Quality Regulation (76/160 / EU: add-on clause 5. Membrane filtration method was used to analyze the samples for coliform bacilli and enterococci. Mandatory values according to bathing water quality regulation were taken as 2000 cfu/100 ml,10000 cfu/100 ml and 1000 cfu/100 ml for fecal coliform, total coliform and enterococcus, respectively. Results: In 196 (84%) of 232 water samples collected, no bacterial contamination was found, while 36 (16%) samples were found contaminated with fecal coliform, total coliform and Enterococcus species. At least one or more specimens of poor quality water were detected in 17 of 29 sampled beaches. Conclusion: It was envisaged to take precautions by restricting the use of the places where microbiological pollution was detected. In addition, regular analyzes are important for public health.

The quality of public sources of drinking water in oil-bearing communities in the Niger Delta region of Nigeria

Background: Studies carried out in the Niger Delta region of Nigeria have demonstrated a link between oil exploration and poor-quality drinking water. However, many of these studies have been limited by small coverage and focus on few parameters. This study thus aimed at a comprehensive assessment of the quality of public sources of drinking water in three gas flaring and three non-gas flaring communities in the Niger Delta region of Nigeria. Methods: A total of 13 samples were collected from the major sources of drinking water in six communities in Rivers, Bayelsa and Delta States, Nigeria. These were stored and transported in line with International standards to a certified environmental laboratory where physical, chemical, bacteriological and petro-chemical assessments were conducted for 27 parameters. Results: Some samples had a pH below the normal range for drinking water, with median pH value of 4.63. All chemical parameters assessed fell below the normal acceptable range with exception of magnesium which exceeded the acceptable range. There were11 samples (91.7%) with microbial contamination; total and faecal coliform demonstrated at values ranging between 15 and 90 most probably number (MPN)/100 ml for total coliform and 9 to 23 MPN/100 ml for faecal coliforms. Oil, grease and total petroleum hydrocarbons (TPH) were identified in water samples from all communities. Values for oil and grease ranged between <0.001 and 0.015 mg/l, while TPH values were between <0.001 and 0.046 mg/l. There was no significant difference between median values in gas flaring and non-gas flaring communities. Conclusion: Distortion of physico-chemical properties, and hydrocarbon and faecal contamination of drinking water are a major challenge in oil-bearing communities in the Niger Delta region of Nigeria irrespective of gas flaring status. This calls for urgent interventions to improve the quality of drinking water for the people of the Niger Delta.

The quality of public sources of drinking water in oil-bearing communities in the Niger Delta region of Nigeria.

Background: Studies carried out in the Niger Delta region of Nigeria have demonstrated a link between oil exploration and poor-quality drinking water. However, many of these studies have been limited by small coverage and focus on few parameters. This study thus aimed at a comprehensive assessment of the quality of public sources of drinking water in three gas flaring and three non-gas flaring communities in the Niger Delta region of Nigeria. Methods: A total of 13 samples were collected from the major sources of drinking water in six communities in Rivers, Bayelsa and Delta States, Nigeria. These were stored and transported in line with International standards to a certified environmental laboratory where physical, chemical, bacteriological and petro-chemical assessments were conducted for 27 parameters. Results: Some samples had a pH below the normal range for drinking water, with median pH value of 4.63. All chemical parameters assessed fell below the normal acceptable range with exception of magnesium which exceeded the acceptable range. There were11 samples (91.7%) with microbial contamination; total and faecal coliform demonstrated at values ranging between 15 and 90 most probably number (MPN)/100 ml for total coliform and 9 to 23 MPN/100 ml for faecal coliforms. Oil, grease and total petroleum hydrocarbons (TPH) were identified in water samples from all communities. Values for oil and grease ranged between <0.001 and 0.015 mg/l, while TPH values were between <0.001 and 0.046 mg/l. There was no significant difference between median values in gas flaring and non-gas flaring communities. Conclusion: Distortion of physico-chemical properties, and hydrocarbon and faecal contamination of drinking water are a major challenge in oil-bearing communities in the Niger Delta region of Nigeria irrespective of gas flaring status. This calls for urgent interventions to improve the quality of drinking water for the people of the Niger Delta.

Nitrifying–denitrifying filters and UV-C disinfection reactor: a combined system for wastewater treatment

ABSTRACTBiological treatment systems use the natural processes of ubiquitous organisms to remove pollutants and improve the water quality before discharge to the environment. In this paper, the nitrification/denitrification reactor allowed a reduction in organic load, but offered a weak efficiency in nitrate reduction. However, the additions of the activated sludge in the reactor improve this efficiency. A decrease of values from 13.3 to 8 mg/l was noted. Nevertheless, sludge inoculation led to a net increase of the number of pathogenic bacteria. For this reason, a UV-C pilot reactor was installed at the exit of the biological nitrification–denitrification device. Thus, a fluence of 50 mJ.cm-2 was sufficient to achieve values of 20 MPN/100 ml for fecal coliform and 6 MPN/100 ml for fecal streptococci, conforms to Tunisian Standards of Rejection. On the other hand, the DGGE approach has allowed a direct assessment of the bacterial community changes upon the treated wastewater.

Fate of parasites and pathogenic bacteria in an anaerobic hybrid reactor followed by downflow hanging sponge system treating domestic wastewater.

Treatment of domestic wastewater in a pilot-scale upflow anaerobic hybrid (AH) reactor (0.9 m(3)) in combination with downflow hanging sponge (DHS) system (1.3 m(3)) was investigated. The combined system was operated at a hydraulic retention time (HRT) of 6.0 h for AH and 3.2 h for DHS system. The total process achieved a substantial reduction of COD(total) resulting in an average effluent concentration of only 39 ± 12 mg/l. Moreover, 90 ± 7% of ammonia was eliminated in the DHS system. Nitrate and nitrite data revealed that 49 ± 3.2% of the ammonia removal occurred through nitrification process. The removal efficiency of total coliform (TC), fecal coliform (FC), and fecal streptococci (FS) was relatively low in the AH reactor. The major portion of TC, FC, and FS was removed in the DHS system resulting to an average count of 1.7 × 10(5) ± 1.1 × 10(2)/100 ml for TC, 7.1 × 10(4) ± 1.2 × 10(2)/100 ml for FC, and 7.5 × 10(4) ± 1.3 × 10(2)/100 ml for FS in the final effluent. Likely, the combined system was very efficient for the removal of protozoological species such as sarcodins (Entamoeba cysts), flagellates (Giardia cysts), and ciliates (Balantidium cysts). This was not the case for coccidia (Cryptosporidium oocysts), where 36.4 and 27.3% were detected in the effluent of AH and DHS system, respectively. Only 10% of intestinal nematode and cestode ova were recorded in the effluent of AH reactor and were completely removed in the DHS system.

Removal of bacterial contaminants and antibiotic resistance genes by conventional wastewater treatment processes in Saudi Arabia: Is the treated wastewater safe to reuse for agricultural irrigation?

This study aims to assess the removal efficiency of microbial contaminants in a local wastewater treatment plant over the duration of one year, and to assess the microbial risk associated with reusing treated wastewater in agricultural irrigation. The treatment process achieved 3.5 logs removal of heterotrophic bacteria and up to 3.5 logs removal of fecal coliforms. The final chlorinated effluent had 1.8 × 102 MPN/100 mL of fecal coliforms and fulfils the required quality for restricted irrigation. 16S rRNA gene-based high-throughput sequencing showed that several genera associated with opportunistic pathogens (e.g. Acinetobacter, Aeromonas, Arcobacter, Legionella, Mycobacterium, Neisseria, Pseudomonas and Streptococcus) were detected at relative abundance ranging from 0.014 to 21 % of the total microbial community in the influent. Among them, Pseudomonas spp. had the highest approximated cell number in the influent but decreased to less than 30 cells/100 mL in both types of effluent. A culture-based approach further revealed that Pseudomonas aeruginosa was mainly found in the influent and non-chlorinated effluent but was replaced by other Pseudomonas spp. in the chlorinated effluent. Aeromonas hydrophila could still be recovered in the chlorinated effluent. Quantitative microbial risk assessment (QMRA) determined that only chlorinated effluent should be permitted for use in agricultural irrigation as it achieved an acceptable annual microbial risk lower than 10−4 arising from both P. aeruginosa and A. hydrophila. However, the proportion of bacterial isolates resistant to 6 types of antibiotics increased from 3.8% in the influent to 6.9% in the chlorinated effluent. Examples of these antibiotic-resistant isolates in the chlorinated effluent include Enterococcus and Enterobacter spp. Besides the presence of antibiotic-resistant bacterial isolates, tetracycline resistance genes tetO, tetQ, tetW, tetH, tetZ were also present at an average 2.5 × 102, 1.6 × 102, 4.4 × 102, 1.6 × 101 and 5.5 × 103 copies per mL of chlorinated effluent. Our study highlighted that potential risks associated with the reuse of treated wastewater arise not only from conventional fecal indicators or known pathogens, but also from antibiotic-resistant bacteria and genes.

Microbiological Quality of Surface Water Treated with &amp;lt;i&amp;gt;Moringa oleifera&amp;lt;/i&amp;gt; Seeds or Cakes during the Storage: Case Study of Water Reservoirs of Loumbila, Ziga and Ouaga 3 Dams in Burkina Faso

Water purification with Moringa oleifera seeds has received a lot of attention because it reduces water turbidity and pathogenic microorganisms. However, it is important to define the optimum conditions of storage to preserve the treated water quality. The study aims to investigate microbial quality of water treated with Moringa oleifera seeds or cake coagulants in relation to the storage temperature and shelf life in order to define the optimum conditions of storage. A total of 45 water samples from 3 water reservoirs of Loumbila, Ziga and Ouaga 3 dams were collected in sterile glass bottles and treated in triplicate with Moringa oleifera seeds or defatted cakes coagulants. Treated water samples obtained at optimum conditions were stored at room temperature (25˚C - 30˚C) and at 4˚C. Fecal bacteria pollution indicators (Escherichia coli, fecal coliforms and fecal streptococcus) and parasites were monitored every 24 hours during three (3) days based on laboratory standard methods. Data were analyzed using the Student's t-test and XLSTAT 7.5.2 statistical software. From the results obtained, bacterial indicators increased significantly with storage temperature (p < 0.0001) and shelf life (p < 0.0001). However, for all water samples, bacterial growth was more important in samples treated with Moringa oleifera cakes than seeds (p < 0.0001). For water samples treated with Moringa oleifera seeds and stored at room temperature, bacterial increase after 72 hours was 57 - 80, 42 - 50 and 22 - 47 CFU/100 ml for fecal coliforms, E. coli and fecal * Corresponding author.

Microbiological and Physicochemical Quality of Well Water Used as a Source of Public Supply

The sources of microbial and chemical contamination of groundwater are numerous and have severe implications for public health. The objective was to determine the microbiological and physicochemical quality of wells in the west and east of the Cuautla-Yautepec aquifer in Mexico. Wells showed bacteriological contamination in at least one sampling. Coliform values were lower than the maximum permissible limit indicated in the Mexican Ecological Criteria of Water Quality (1000 colony forming unit (CFU)/100 ml of fecal coliforms) for supply sources. The number of isolated amoebae was low, but these were present all year round. Amoebae were found in 71.7% of the samples and belonged to 13 genera. The most frequent amoeba, Hartmannella, occurring in 44% of the samples, has been associated with eye and brain infection, but its role as a cause of infection has not been confirmed. A gradient was observed for dissolved solids according to altitude; the concentrations of dissolved solids increased in wells with lower altitudes. Total hardness values were above 180 mg/L CaCO3, therefore the water is considered very hard, and both carbonate and non-carbonate hardness was detected. The average values of physicochemical parameters were below the maximum permissible limits indicated in the Mexican official norm.

Groundwater contamination by microbiological and chemical substances released from hospital wastewater: Health risk assessment for drinking water consumers

Contamination of natural aquatic ecosystems by hospital wastewater is a major environmental and human health issue. Disinfectants, pharmaceuticals, radionuclides and solvents are widely used in hospitals for medical purposes and research. After application, some of these substances combine with hospital effluents and, in industrialised countries, reach the municipal sewer network. In certain developing countries, hospitals usually discharge their wastewater into septic tanks equipped with diffusion wells. The discharge of chemical compounds from hospital activities into the natural environment can lead to the pollution of water resources and risks for human health. The aim of this article is to present: (i) the steps of a procedure intended to evaluate risks to human health linked to hospital effluents discharged into a septic tank equipped with a diffusion well; and (ii) the results of its application on the effluents of a hospital in Port-au-Prince. The procedure is based on a scenario that describes the discharge of hospital effluents, via septic tanks, into a karstic formation where water resources are used for human consumption. COD, Chloroform, dichlomethane, dibromochloromethane, dichlorobromomethane and bromoform contents were measured. Furthermore, the presence of heavy metals (chrome, nickel and lead) and faecal coliforms were studied. Maximum concentrations were 700 NPP/100 ml for faecal coliforms and 112 mg/L for COD. A risk of infection of 10 − 5 infection per year was calculated. Major chemical risks, particularly for children, relating to Pb(II), Cr(III), Cr(VI) and Ni(II) contained in the ground water were also characterised. Certain aspects of the scenario studied require improvement, especially those relating to the characterisation of drugs in groundwater and the detection of other microbiological indicators such as protozoa, enterococcus and viruses.

Occurrence of Ciprofloxacin‐, Trimethoprim‐Sulfamethoxazole‐, and Vancomycin‐Resistant Bacteria in a Municipal Wastewater Treatment Plant

The occurrence of antibiotic-resistant bacteria was evaluated in aqueous samples obtained from a municipal wastewater treatment plant. Samples collected from the influent, clarifier effluent, and disinfected effluent were assayed for fecal coliforms, E. coli, and enterococci exhibiting resistance to ciprofloxacin, trimethoprim-sulfamethoxazole, and vancomycin. Membrane filtration of samples was followed by plating on growth media containing various concentrations of antibiotic. Bacterial colonies on plates with antibiotic exposures greater than the clinical minimum inhibitory concentrations were counted and considered resistant. The numbers of drug-resistant organisms in influent ranged from nondetectable to 7 x 10(5) colony-forming units (CFU)/100 mL for fecal coliforms, nondetectable to 5 x 10(4) CFU/100 mL for E. coli, and nondetectable to 6 x 10(5) CFU/100 mL for enterococci. Fecal coliforms, E. coli, and enterococci with reduced susceptibility to antibiotics were also detected in influent and clarifier effluent; however, the disinfected effluent did not contain resistant bacteria. Species-level identification of enterococci revealed that resistant enterococci were predominantly E. faecalis.

Post-treatment and reuse of tertiary treated wastewater by constructed wetlands

Three pilot-scale constructed wetland (CW) units were built in an area near to Paşaköy Advanced Biological Wastewater Treatment Plant (PWWTP) in Istanbul in 2002. The aim of this study was to evaluate the effectiveness of constructed wetland systems in the removal of organic matter from tertiary effluents and the potential factors effecting removal. The first pilot system is a gravel-substrate horizontal-subsurface flow (H-SSF) wetland (7.5 × 20 m) planted with Cyperus. The second is a without substrate and surface flow (SF) wetland system (7.5 × 20 m) with Cyperus. The third is a four serial-connected free water surface flow (FWS) wetland system (each 6.5 × 8 m) planted with Lemna. Pilot systems were operated for a period of 3 years. The hydraulic loading rate varied between 4.8 and 15.6 m 3 d −1. The average removal efficiencies were higher in summer periods. The average removal values at H-SSF, FWS and SF systems were 80%, 65% and 72% for SS; 65%, 64% and 62% for BOD 5; 50%, 45% and 47% for COD; 29%, 34% and 37% for TOC, respectively. The average overall removal of fecal coliform and total coliform were 94% (with an average effluent 140 cfu/100 mL for fecal coliform and 1240 cfu/100 mL for total coliform). Removal efficiencies were affected rather by hydraulic residence time (HRT) and mass loading rates (MLR). Statistical analysis (ANOVA) showed that there was significant difference between temperatures and loading rates (MLR and HRT) and removal efficiencies. TUKEY-HSD tests demonstrated that there was not statistically significant difference between configurations in BOD 5, COD and TOC removal. The results of this study demonstrated that constructed wetlands had a potential for BOD 5, COD and coliform removal and the treatment and reuse of tertiary effluents.

Bacteriological analysis of borehole water in Uli, Nigeria

Water samples from four different boreholes within Uli, Anambra State, Nigeria, were collected for five consecutive weeks for bacteriological analysis to assess the potability.The range of the means was from 1.5x102 to 5.9x104 cfu ml-1 for total aerobic bacterial load, 9 to 136 MPN per 100ml for total coliforms and 4 to 74 MPN per 100ml for faecal coliforms. The highest counts were consistently found in the sample from Cagramento Lodge, where the borehole was located in an unsanitary environment, near a pit laterine. Escherichia coli, Klebsiella sp., Proteus sp., Enterobacter sp., Pseudomonas sp., and Staphylococcus aureus were isolated from the samples. The findings show that the water from all the boreholes did not meet the World Health Organization Standards for Drinking Water and should be treated or boiled and filtered before drinking. Keywords : Faecal coliforms, borehole water, Uli, Nigeria AJAZEB Vol. 7 2005: pp. 116-119

The Role of Wastewater Treatment in Protecting Water Supplies Against Emerging Pathogens

Traditionally, regulators, dischargers, and even water suppliers believed that wastewater discharge meeting the levels of 200 cfu/ 100 mL of fecal coliforms in wastewater effluent was sufficient to protect against downstream microbial effects. However, these beliefs are now being challenged by emerging pathogens that are resistant to standard water and wastewater treatment processes, exhibit extended survival periods in the environment, can adversely affect sensitive subpopulations, and require extremely low doses for human infection. Based on this new information, it is estimated that discharges of emerging pathogens from conventional wastewater treatment plants as far as 160 km upstream and cumulative amounts of wastewater discharge ranging from 2 to 20 ML/d have the potential to reach a water supply intake in a viable state at significant concentrations that could exceed regulatory limits for drinking water supplies, increase endemic risk from drinking water, and/or require additional drinking water treatment. Wastewater dischargers may be able mitigate this potential effect and achieve upwards of 6 log combined removal and inactivation of emerging pathogens to mitigate drinking water effects by using alternative treatment processes, such as filtration or UV light disinfection, or optimizing these processes based on site-specific conditions.

Constructed wetlands effluent for streamflow augmentation in the Besòs River (Spain)

There is nowadays a tendency in the south of Europe to recover the natural features of urban rivers as much as possible. The final part of the Besòs River (Spain) flows inside a heavily industrialized area in greater Barcelona. Following a classical model in the 1970s, the river was canalized, theoretically to reduce the high flow impact but in practice to gain flat areas where building was easy. The result was many artificially created impervious areas which made infiltration difficult, and the invasion of the river-related high-flow zones by industrial facilities and urbanized areas. Additionally, for several decades, the Besòs River was the most altered fluvial basin of Catalonia. Trying to improve the really bad conditions of that section of the river, a big conversion of part of its final section was undertaken in the 1990s. There, the low flow concrete channel was re-naturalized, bending it, and in the reclaimed bed surface an urban park and a tertiary wastewater treatment system were implemented. After treatment, the effluent directly enters the river, thus improving water quality. Water from the tertiary treatment, constructed wetlands, has the following percentage of removal if compared with the effluent of the activated sludge facility: 40% for suspended solids; 62% for COD; 20% for NH + 4-N; 58% for P; and 1.1 log U/100 mL for fecal coliforms.

Scope of potential bacterial agents of diarrhoea and microbial assessment of quality of river water sources in rural Venda communities in South Africa

The microbial quality of several, usually untreated, surface domestic water sources, used by rural communities in the Venda Region of South Africa, was assessed to gauge their fitness for human consumption and to highlight the possible impact of waterborne diseases. The water sources studied were six points on the Levubu River and the rivers Mutale, Ngwedi, Tshinane, Makonde, Mutshindudi and Mudaswali. Total and faecal coliform, heterotrophic bacteria, enterococci and coliphage counts were used as indicators/surrogates to estimate the degree of bacterial and viral contamination respectively by standard methods. The presence of potential bacterial agents of diarrhoea such as Salmonella, Shigella, Campylobacter, Plesiomonas, Aeromonas and Vibrio was also determined. Results showed that the ranges of counts with regard to all the water sources investigated were 2.9 x 10(2) - 6.3 x 10(4) CFU/100 mL for faecal coliforms, 6.0 x 10(2) - 3.7 x 10(4) CFU/100 mL for total coliforms, 1.8 x 10(2) - 1.3 x 10(6) CFU/mL for heterotrophic plate count, 1.0 x 10(1) - 3.7 x 10(4) CFU/100 mL for enterococci and 0-13 PFU/100 mL for coliphages. These values are far higher than the acceptable maximum limits prescribed for South Africa by the Dept of Water & Forestry and the Water Research Commission - 0 CFU/100 mL, 5 CFU/100 mL, 1.0 x 10(2) CFU/mL, 0 CFU/100 mL and 1 PFU/100 mL for faecal coliforms, total coliforms, heterotrophic bacteria, enterococci and coliphages respectively. Salmonella, Shigella, Vibrio cholerae, Campylobacter, Aeromonas and Plesiomonas were isolated from several of the water sources investigated. The use of these water sources for drinking and domestic purposes poses a serious threat to the health and well being of the users and calls for urgent government intervention.

Comparison of advanced disinfecting methods for municipal wastewater reuse in agriculture

The experimental investigation carried out jointly by Italian and Israeli teams within a 3-year research project funded by the European Commission on alternative disinfection methods for reusing municipal wastewater in agriculture is described. Disinfection effectiveness of UV rays, ozone (O3) and peracetic acid (PAA) at pilot scale and hydrogen peroxide (H2O2) plus silver (Ag+) or copper (Cu+2) at laboratory scale was compared for tertiary municipal effluents. Pilot plant results indicated that the well known California limit (2 CFU/100ml of Total Coliforms) was effectively met with reasonable UV doses of 100–160 mWs/cm2 or with exceedingly high PAA dosage (400 PPM); the related WHO microbial guideline (1,000 CFU/100 ml of Fecal Coliforms) was easily met with all three disinfectants (UV, PAA, O3); maximum log-inactivation values were ≥5 for UV and PAA and ≤4 for O3. Laboratory results with tertiary effluents demonstrated that Ag+ was able to inactivate target bacteria (E. coli-B, E. coli-K12), while H2O2 was more effective than Ag+ against MS-2 phages. Copper (250 μg/l) had no bactericidal effect but possessed an appreciable virucidal effect. When hydrogen peroxide and copper were combined, a pronounced increase in both bactericidal and virucidal effects was obtained.

Microbial quality and persistence of enteric pathogens in graywater from various household sources

This study was designed to evaluate the microbial quality and safety of graywater for reuse purposes. The microbial and chemical composition of graywater from shower/bath, wash cycle and rinse cycle of a clothes washing machine was determined. Graywater composed from all sources within a house was also monitored each week over a 2–3-month time period. Samples were taken from a diverse group of families with children (18 months–9 years of age) and without children. Standard plate count bacteria (SPC) ranged from 10 5 to 10 10 colony forming units (cfu) per 100 ml for shower and bath water, and an average of 10 4 to 10 6 cfu per 100 ml for total coliforms. Families with small children produced wash cycle graywater containing 10 6 cfu per 100 ml of fecal coliforms. During investigations on storage of graywater, it was found that total bacterial SPC and coliform baceria increased one order of magnitude. Salmonella atyphimurium and Shigella dysenteriae seeded into graywater were found to persist for at least several days. Poliovirus type 1 added to graywater decreased 99 and 90% at 25 and 17°C, respectively, after 6 d of storage in graywater. These data imply that there may be some risk associated with reuse of graywater when these pathogenic bacteria or viruses are being excreted by an individual producing the graywater.