A comparative assessment of chemical contaminant removal by three household water treatment filters

This study was aimed at modifying the design of, constructing, evaluating and comparing chemical contaminant removal efficiency by, 3 household water treatment filters. The filters were: 1) biosand filter (BSF); 2) the ceramic candle filter (CCF); 3) bucket filter (BF). The filters were evaluated for their efficiency in removal of calcium, magnesium, iron and arsenic, nitrates, phosphates, fluorides, total organic carbon and turbidity, by determining levels of these contaminants in water before and after filtration through the filters. The effects of chlorophyll a concentration(mg/m3) of intake water, as well as the effects of turbidity of  intake water, on the flow rates of the filters was quantified and recommendations on the quality of water that could be filtered through these filters were made. Chlorophyll a concentrations in intake water had a positive correlation with the turbidity of the unfiltered water (r = 0.607).The flow rates of the filters were 0.8 ℓ/h - 6.48 ℓ/h (BSF), 0.05 ℓ/h - 2.495 ℓ/h (CCF) and 106.5 ℓ/h - 160.5 ℓ/h (BF). Because of the large particle size materials used in constructing  the BF and the design, which caused it to be a rapid sand filter, the biosand filter (BF) was found to have flow rates significantly higher than those of BSF and CCF (p ≥ 0.05). There was no difference in the efficiency of removal of metals (average 40% - 50%) by the filters (p ≥ 0.05), as the same removal mechanisms (straining, ammonification, fixation and adsorption) were believed to be taking place in all of the filters. The CCF removed total organic carbon (TOC) (up to 39%) better than the BSF and BF (p ≤ 0.05). The filters removed turbidity effectively with the BSF having the highest reduction (70%). The average turbidity reduction efficiency was in the order BSF (70%) > BF (51%) > CCF (44%). The BSF, CCF and BF reduced turbidity and other contaminants even after filtering a total cumulative volume greater than 1 000 ℓ.Keywords: Biosand filter, bucket filter, ceramic candle filter, flow rate, chlorophyll a

Survey of disinfection efficiency of small drinking water treatment plants: Challenges facing small water treatment plants in South Africa

A survey involving 181 water treatment plants across 7 provinces of South Africa: Mpumalanga, Limpopo, North West, Free State, KwaZulu-Natal, Eastern Cape and Western Cape was undertaken to identify the challenges facing small water treatment plants (SWTPs) in South Africa . Information gathered included ownership and design capacity of the plants, water sources, and various methods of disinfection, equipment currently employed and performance of the treatment plants. In general, the majority (over 80%) of the SWTPs surveyed in the designated provinces were owned by the district municipalities. The designed capacities of these plants varied between 1 and 60 M./d; the smallest capacity was 100 m3/d and the largest 120 M./d. The small water treatment plants abstracted their raw water from either surface or groundwater or a combination of both water sources with greater preponderance for surface water sources (over 86%). Water treatment practices were noted to be the conventional types mainly coagulation, flocculation, sedimentation, filtration and disinfection. Two types of coagulants namely polyelectrolyte (66%) and alum (18%) were commonly used by the water treatment plants across the provinces studied. Rapid gravity filtration, pressure filter and slow sand filtration systems accounted for 60%, 23% and 9% of the filtration systems across the provinces, respectively. The predominant types of disinfectants employed were chlorine gas (69%) followed by sodium (15%) and calcium (14%) hypochlorite. Over 50% of the various SWTPs did not complywith the SANS 241 Class I (< 1 NTU) and Class II (1 to 5 NTU)  recommended turbidity values. The recommended target range of 0.3 to 0.6 mg/. free chlorine residual concentrations at the point of use was not always met by 40% of the plants. Seventy percent of the SWTPs complied with the SANS 241 criteria of microbiological safety of drinking water vis-a-vis total and faecal coliforms. Operational problems affecting the efficiency of small water treatment plants included: inability to appropriately determine the flow rate, chemical dosage and turbidity, lack of chlorine residual at the point of use and lack of water quality monitoring. To produce safe drinking water, appropriate operational practices must be implemented in all small water treatment plants

Prevalence of enterohaemorrhagic Escherichia coli O157:H7 in drinking water and its predicted impact on diarrhoeic HIV/AIDS patients in the Amathole District, Eastern Cape Province, South Africa

Immunosuppressed persons such as HIV/AIDS patients are at risk of acquiring diarrhoeal infections from water-borne E. coli O157:H7. In the present study, we investigated the prevalence of E. coli O157:H7 in drinking water collected from selected distribution systems within the Amathole District of the Eastern Cape and its predicted impact on diarrhoeic conditions of HIV/AIDS persons living in this area. One hundred and eighty water samples and 360 stool swabs from confirmed and nonconfirmed HIV/AIDS diarrhoeic patients were analysed. Escherichia coli O157:H7 were isolated using enrichment culture and confirmed using molecular techniques. Of the 180 drinking water samples, 46 (25.56%) were positive for E. coli O157. The prevalence of E. coli O157 in the stools was at 36.39% (131/360) of which 56.5% (74/131) and 43.5% (57/131) were from stools of confirmed and non-confirmed HIV/AIDS patients, respectively. Molecular analysis of 27, 25 and 29 representative presumptive E. coli O157 from water and stools of confirmed and non-confirmed HIV/AIDS patients, respectively, revealed that 14.81%, 36% and 17.24% of the isolates were E. coli O157:H7. The findings predicted a possible link between E. coli O157:H7 isolated from drinking water and diarrhoeic conditions of both confirmed and non-confirmed HIV/AIDS patients visiting Frere Hospital for treatment.Keywords: prevalence, drinking water, HIV/AIDS, stool specimens, Escherichia coli O157:H7 and PC

Focus on 14 sewage treatment plants in the Mpumalanga Province, South Africa in order to gauge the efficiency of wastewater treatment

In order to identify the treatment methods used in different sewage treatment plants (STPs) in the Mpumalanga Province and to determine the efficiency of wastewater treatment by these plants,municipal STPs were surveyed, and raw and treated wastewater samples collected. A total of 14 STPs were visited and the collected samples were analysed for physicochemical and microbiologicalparameters using standard methods. The treatment methods identified included ponds, activated sludge and trickling filters. The reduction of turbidity by the plants varied between 6.2 and 99.6% whileconductivity, pH and temperature varied slightly between the influent and the effluent wastewater. Thirteen (92.8%) of the plants used chlorine for disinfection of the final effluent, however only 2 (14.2%)of the plants managed to produce effluent with 0 (zero) faecal coliforms per 100 m. Common pathogenic bacteria isolated from the final effluent included Salmonella, Shigella, Escherichia coli, Vibrio spp. and Enterococcus spp. The final effluent was used for irrigation and recycling purposes in 4 plants, all the other treatment plants discharged the effluent into the river or to the environment. Thepresent study indicated that there is a move toward the renovation of wastewater treatment by the municipalities in the Mpumalanga Province with the adoption of biological treatment. All the STPs reduced the turbidity of wastewater as well as the different microbial indicators counts; however, several pathogenic bacterial organisms could still be detected in the final effluent. Further studies are needed to confirm the role of the treatment procedures on nutrient reduction and elimination of other viral and parasitic pathogens by the sewage treatment plants

Antibacterial activity of honey and medicinal plant extracts against Gram negative microorganisms

There has been a steady rise in antibiotic resistance of bacteria and this urgently calls for the discovery of alternative therapeutic agents. Honey possesses therapeutic potentials which includes antimicrobial activity. Although the antimicrobial activity of honey has been effectively established against an extensive spectrum of microorganisms, it differs depending on the type of honey. To date, not much extensive studies of the antibacterial properties of South African honeys on enteric microorganisms have been conducted. The objective of this study was to compare the antibacterial activity of extracts of six different honeys with those of medical plants commonly used in South Africa. Using a broth dilution method, the antibacterial activity extracts of six South African honeys and medicinal plants against six enteric microorganisms viz- Enterobacter cloacae, Escheriachia coli, Klebsiella pneumoniae, Citrobacter freundii isolated from geophagia samples and Aeromonas hydrophila and plesiomonas isolated both from stool and water samples using agar well diffusion method was done. Different concentrations of honey and plant extracts were tested against each type of microorganism. Briefly, two-fold dilutions of honey solutions were tested to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against each type of microorganism. Extracts from both South African honeys and medicinal plants showed zones of inhibition that ranged from 6.94 to 37.94 mm. The most susceptible bacteria were Escheriachia coli, Aeromonas hydrophila and Plesiomonas shigelloides. MIC and MBC values of extracts were found in the range of 0.625 to 5.000 mg/ml. Extracts of honey showed good antibacterial activity against most organisms than the standard antibiotics such as Ampicillin and Gentamycin. Honey extracts showed antibacterial activity against most microorganisms which were showing some degree of resistance to commercial antibiotics. Extracts from South African honeys and medicinal plants exhibited variable activities against different microorganisms. This result suggests that the honeys could potentially be used as an alternative therapeutic agent against certain microorganisms.Keywords: Agar well diffusion assay, honey, minimum inhibitory concentration, minimum bactericidal concentrationAfrican Journal of Biotechnology, Vol. 13(4), pp. 616-625, 22 January, 201

Antibiotic resistance profiles and relatedness of enteric bacterial pathogens isolated from HIV/AIDS patients with and without diarrhoea and their household drinking water in rural communities in Limpopo Province South Africa

Antibiotic resistance profiles and the correlation of enteric bacterial pathogens from HIV positive individuals with and without diarrhoea and their household drinking water were determined using the KirbyBauer disk diffusion and polymerase chain reaction methods respectively. The sef gene of Salmonella enteritidis was amplified with the primer pair sefA-1 and sefA-2. The fliC gene of Salmonella typhimurium was amplified with the primer pair flicA-1 and flicA-2. Heat-labile toxin (LT) primers (Lta and LTb) were used to amplify Escherichia coli isolates and VirA1 and VirA2 for the Vir A gene of Shigella dysenteriae. Results of antibiotic resistance profiles of enteric bacterial pathogens isolated from stool samples of HIV positive and negative individuals with and without diarrhea and their household drinking water showed very similar drug resistance patterns. Over 90% of all the organisms isolated from the various study cohorts showed resistance to penicillin, cloxacillin and amoxicillin. Conversely, almost all the organisms were sensitive to ciprofloxacin, gentamycin, meropenem and imipenem. About 50% of E. coli isolated from the various study cohorts showed multiple antibiotic resistance to penicillin, amoxicillin, ampicillin, erythromycin, tetracycline, doxycycline and cotri-moxazole ( PR, AR, APR, ER, TR, DXTR, and TSR ) whereas less than 10% resistance was consistently reported for ofloxacin, gentamycin, meropenem cefotaxime, cefuroxime and imipenem ( OFXS, GMS, MEMS, CTXS, CXMS and IMIS ). The majority of Salmonella and Shigella isolates from all the groups were sensitive to ciprofloxacin, gentamicin, amikacin, meropenem, imipenem, nalidixic acid, kanamycin, piperacillin-tazo bactam, cefuroxime, doxycyclin, cefepime and ceftazidime (CIPS, GMS, AKS, MEMS, IMIS, NAS, KNS, DXTS, CXMS, CPMS, CAZS and PTZS). For Campylobacter, over 30% of the isolates were resistant to erythromycin, ampicillin, tetracycline,cotrimoxazole and ceftazidime (ER, APR TSR and CAZR) whereas over 85% were susceptible to ciprofloxacin, ofloxacin, gentamycin, amikacin, mero-penem, and nalidixic acid (CIPS, OFXS, GMS, AKS,MEMS and NAS). In addition to penicillin, amoxicillin, ampicillin and erythromycin, Aeromonas and Plesiomonas spp were more resistant to chloramphenicol, but were susceptible to ciprofloxacin, gentamycin, amikacin, meropenem, imipenem and nalidixic acid (CIPS, GMS, AKS, MEMS, IMIS and NAS). Polymerase Chain Reaction (PCR) experiments using targeted species genes of S. enteritidis, S. typhimurium, E. coli, Sh. dysenteriae showed that isolates from stool samples of HIV positive and HIV negative individuals with and without diarrhoea were also present in the household drinking water of the same study cohorts, suggesting that drinking water may have been the sources of the organisms in stool sample. Furthermore, by showing that the primers were able to amplify the genes in both clinical and environmental isolates, the link between the virulence of the pathogens was established

Identification of Escherichia coli strains from water vending machines of Kelantan, Malaysia using 16S rRNA gene sequence analysis

Water vending machines provide an alternative source of clean and safe drinking water to the consumers. However, the quality of drinking water may alter due to contamination from lack of hygienic practices and maintenance of the machines. Hence, this study was conducted to determine the microbiological quality of water from vending machines and associated contact surfaces. Seventeen water samples and 85 swab samples (nozzles, drip trays, coin slots, buttons and doors) from 3 locations in Kelantan were collected. Polymerase chain reaction amplification and 16S ribosomal ribonucleic acid (rRNA) sequencing were carried out and sequences obtained were compared against the sequences available in the National Centre for Biotechnology Information database using the basic local alignment search tool programme. Coliform counts were observed in 94.12 % of water samples, 76.47 % of nozzles and 82.35 % of drip tray swabs. Furthermore, results of 16S rRNA sequence analysis indicated that two gram-negative isolates were identified as Escherichia coli U 5/41 (Accession no. NR_024570.1) and E. coli O157:H7 EDL933 (Accession no. CP008957.1) with similarity value of 100 %, respectively. The results from this study further improve our understanding of the potential microorganisms in drinking water. Regular maintenance and cleaning of water vending machines are important to reduce bacterial growth and the presence of waterborne pathogens

Priority water research questions for South Africa developed through participatory processes

This paper describes a collaborative process of identifying and prioritising current and future water research questions from a wide range of water  specialists within South Africa. Over 1 600 questions were collected,  reduced in number and prioritised by specialists working in water research and practice. A total of 59 questions were finally proposed as an outcome of the study and are categorised under the themes of change, data, ecosystems, governance, innovation and resources. The questions range in scale, challenge and urgency, and are also aligned with prevailing  paradigms in water research. The majority of the questions dealt with relatively short- to medium-term research requirements and most focused on immediate issues such as water supply, service delivery and technical solutions. Formulations of long-term research questions were sparse,  partly because some of the principles and methods used in this study were difficult to apply in the South African context, and also because researchers are influenced by addressing what are believed to be the more immediate, short-term water-related challenges in South Africa. This is the first  initiative of its kind to produce a comprehensive and inclusive list of research priorities for water in South Africa.Keywords: research, questions, collaboration, prioritisation, South Afric

Experimental based experiences with the introduction of a water safety plan for a multi-located university clinic and its efficacy according to WHO recommendations

BACKGROUND: Due to the high number of immunosuppressed and other predisposed patients hospitals have to control and ensure the microbiological water quality. The origin for the occurrence of pathogenic microorganisms in water pipes is the formation of biofilm. METHODS: For the permanent control of water safety a water safety plan (WSP) was realized as recommended by the WHO following the principle "search and destroy". The WSP is based on an established HACCP concept due to the special focus. The most important measures include the concept for sample taking depending on patient risk. 3 different categories) are distinguished: risk area1 (high infection risk), risk 2 (moderate infection risk), and risk area 3 (not increased infection risk). Additionally to the threshold value of the German law for the quality of drinking water (TrinkwV) three more limiting values were defined (warning, alert, and worst case) for immediate risk adapted reaction. Additional attention has to be focussed on lavatory sinks, which are an open bacterial reservoir. Therefore continuous disinfecting siphons were installed as part of the WSP in high risk areas. If extended technical equipment is not available, especially for immunocompromised patients the following measures are easy to realize: boiled (or sun exposed) water for nursing procedures as well alimentary use, no showering. RESULTS: Comparing data over 3 years the microbial water quality was significantly improved resulting in no new case of nosocomial Legionella pneumoniae and decrease in neonatal sepsis. CONCLUSION: According to average situations with highly contaminated water system the management must be defined with implementation of water task force, immediate providing of special equipment, information of patients and staff and control of the water quality, an example for successful decontamination of the hospital within 24 hours is given

The effects of pH and temperature on phosphate and nitrate uptake by wastewater protozoa

The objective of this study was to ascertain the effects of pH and temperature on nutrient uptake efficiency of 3 wastewater protozoan isolates (Aspidisca (A), Trachelophyllum (B) and Peranema (C))that have previously been screened for nutrient uptake ability. The study was carried out in shake flask at pH 5, 6, 7, 8 and 9 and incubation temperatures of 25, 30 and 35oC for 96 h. The results revealed optimum pH ranges for the uptake of phosphate and nitrate to be 7 to 9 and 5 to 7, respectively. Maximum nutrient uptake was found to occur at 25oC with phosphate concentration decreasing from64.74 to 10.21 mg/l, 63.09 to 8.54 mg/l and 64.47 to 6.36 mg/l, for isolates ‘A’, ‘B’ and ‘C’, respectively. Also, nitrate concentration was found to decrease from 24.71 to 4.91 mg/l for isolate ‘A’, 24.47 to 11.15 mg/l for isolate ‘B’, and 24.58 to 15.00 mg/l for isolate ‘C’ at the same temperature. An increase in COD was observed in mixed liquor inoculated with the test isolates. The study has been able to give aninsight into the optimum temperature and pH for phosphate and nitrate uptake by the isolates