Universal access to safe water, whether at households or health centres, is central to achieving the sixth sustainable development goal by 2030. A hospital-based survey was conducted to screen for antimicrobial resist...Universal access to safe water, whether at households or health centres, is central to achieving the sixth sustainable development goal by 2030. A hospital-based survey was conducted to screen for antimicrobial resistance among coliforms in samples collected from tap water (n = 54) at surgical wards in Gaza and to investigate the association with free residual chlorine and pH levels. Total coliforms (TC) were detected in 48.1% (26/54) of tested samples and FCs were detected in 25.9% (14/54). Free residual chlorine test ranged from zero to 0.2 mg/l (average: 0.08 mg/l), of which more than half of the samples (53.7%) 29/54 showed no free residual chlorine. The mean value of free residual chlorine in samples tested positive for growth on m-Endo (0.03) was lower than the mean for negative samples (0.14). The pH values were within the acceptable range (average: 7.6) and there was a statistically significant variation between the mean of pH values for samples tested positive on m-Endo (7.29) and that tested negative (7.84). Among coliform positive samples, 23.1% (6/26) had coliform isolates with resistance patterns. More than two-thirds of antimicrobial resistant (AMR) isolates were resistant to amikacin, ceftazidime, ceftriaxone, and imipenem. Moreover, 50% of the isolates were resistant to piperacillin-tazobactam. One-third (33.3%) of isolates were resistant to cefoxitin, and fosfomycin, 16.7% were resistant to ciprofloxacin, and nitrofurantoin. Intermediate resistance was shown in 16.7% of the isolates to cefoxitin and ciprofloxacin. The ESBL and carbapenem resistance genes detected in isolates were TEM (66.7%), NDM (33.3%), OXA (25%), blaCTXM (16.7%), and blaCTXM-3 (16.7%). The finding highlighted the level of contamination with AMR coliform in samples collected from tap water and pointed out the importance of managing water safety through identifying the main source of contamination, in addition to maintaining proper water disinfection at healthcare facilities for the patient, staff and environmental safety.展开更多
This study is aimed at evaluating alternative designs of waste stabilization ponds (WSPs) and constructed wetlands (CWs) for Kaputiei Housing Estate consisting of 2000 low cost housing units in Kenya. The entire analy...This study is aimed at evaluating alternative designs of waste stabilization ponds (WSPs) and constructed wetlands (CWs) for Kaputiei Housing Estate consisting of 2000 low cost housing units in Kenya. The entire analysis was carried out by simulating the effectiveness and purification efficiencies of WSPs and CWs in terms of Biological Oxygen Demand (BOD) reduction and faecal coliform (FC) removal under different scenarios of water treatment systems that included Re-sizing of the initial sewage treatment system, optimizing the design of the initial system and design of hybrid system for the estate. The graphic comparison of the simulated parameters under different scenarios showed that a hybrid design that combines both the WSPs and CWS provides an effluent BOD of 20 mg/l and 195 FC per 100 ml that meets the standard effluent discharge that is acceptable for unrestricted crop irrigation and thus will be reused in the housing estate for kitchen gardening and agroforestry.展开更多
A well surveillance study carried out in nine Divisional Secretariat Divisions on the west coast of Sri Lanka showed that 70.3% of 101 well sampling points were microbially contaminated with equal to, or greater than,...A well surveillance study carried out in nine Divisional Secretariat Divisions on the west coast of Sri Lanka showed that 70.3% of 101 well sampling points were microbially contaminated with equal to, or greater than, faecal coliform grade C (11 - 100 cfu/100 mL). Due to the very vulnerable hydro-geological setting of the coastal sand, laterite and alluvium aquifers occurring in the study areas, the recommended safe separation distance between an on-site sanitation system and a well could not be achieved. Hence, a cardinal rule of well protection was observed to be broken at almost every well study site. The existing excreta disposal systems need to be improved or replaced with more efficient ones before the impact of other sanitary hazards at the well, and wellhead area, on the microbial quality of well water, can be determined and addressed. The published (WHO, 1997) sanitary survey forms for open dug wells and tube wells need to be modified in the context of the study areas described. Based on a comparison of three different statistical methods used to assess the relative significance of each sanitary hazard modification to the methodology for determining the sanitary hazard index (SHI) was prescribed.展开更多
Concern for saline and microbial quality post-December 2004 tsunami, led to a field based surveillance study to systematically investigate the sanitary hazards which cause faecal contamination of groundwater. In seven...Concern for saline and microbial quality post-December 2004 tsunami, led to a field based surveillance study to systematically investigate the sanitary hazards which cause faecal contamination of groundwater. In seven islands, two duplicate sample sets, in two surveys, revealed that only 6.4% of the 173 well water samples (combining both surveys) satisfied the WHO Drinking Water Quality Guideline for 44°C thermo-tolerant (Faecal) Coliform (FC) indicator value (zero cfu/100 ml sample). Based on a combined risk analysis of Sanitary Hazard Score (SHS) and FC counts, more than 57.7% of the study wells were classified as at very high (FC: 100 to >1,000 cfu/100ml;and SHS: ≥ 9) microbial health risk. During this study, fundamental changes were made to the published generic sanitary inspection method (WHO, 1997) for identifying sanitary hazards, for its application in the extremely vulnerable hydro-geological setting of the Maldives. However, the most important hazard controlling the intensity of faecal contamination in the Maldives is the safe separation distance between a latrine seepage point and the well. It was demonstrated that, due to the prevailing hydro-geological conditions and the well and sanitation system densities, safe separation distance cannot be achieved. Consequently, septic tank effluent quality must be greatly improved.展开更多
The rational for this study was to assess the microbial quality of fresh vegetables at the farm gate of the Water Works road vegetable farm at Gumbihini in the Tamale Metropolis. A total of thirty-six (36) vegetables ...The rational for this study was to assess the microbial quality of fresh vegetables at the farm gate of the Water Works road vegetable farm at Gumbihini in the Tamale Metropolis. A total of thirty-six (36) vegetables comprising lettuce, amarantus and cabbages and eight (8) wastewater samples were collected at random and analysed for a period of four months, to assess the microbial contamination level. Samples were analysed for total coliforms, faecal coliforms, E. coli and helminthes eggs. All vegetables sampled during the study period recorded high levels of total and faecal coliform bacteria. Mean faecal coliforms for the various vegetables were as follows;lettuce 3.7 ± 0.5 CFU.g-1, amarantus 3.5 ± 0.6 CFU.g-1 and cabbage 3.1 ± 0.6 log CFU.g-1 fresh weight. FC levels were above the International Commission on Microbiological Specifications for Foods (ICMSF) recommended level of 3 log CFU.g-1 fresh weight. E. coli were recorded in lettuce (3.3 ± 0.6 log CFU.g-1 fresh weight) and amarantus (0.6 ± 0.1 log CFU.g-1 fresh weight) but not in cabbages. Lettuce generally recorded high levels of microbial contamination because of the large surface area occupied by its leaves. Two helminth eggs (Strongiloides stercoralis) were identified in lettuce while four (Ascaris lumbricoides) were identified in wastewater. Microbial loads recorded in wastewater were generally higher than that of vegetables. Since most of these vegetables are eaten fresh or slightly cooked, there is course for concern as public health will be adversely affected. Education of farmers and consumers on food safety has to be intensified to avert a possible outbreak.展开更多
This study investigated the quality of ground water in Baba I, North-West Cameroon, in order to determine its suitability for domestic uses following World Health Organisation (WHO) guidelines. Inhabitants of this loc...This study investigated the quality of ground water in Baba I, North-West Cameroon, in order to determine its suitability for domestic uses following World Health Organisation (WHO) guidelines. Inhabitants of this locality consume water from these sources without any prior treatment which can lead to health problems if the water sources are contaminated. Six water sources were sampled in November 2017, January, April and July 2018 and examined for organoleptic, physico-chemical and bacteriological parameters using standard methods. Results of organoleptic and physical parameters showed that most of the sources were within the WHO acceptable limits with pH varying from moderately acidic to weakly basic. Chemical properties revealed that all the analysed ions were found within the WHO guidelines and the water sources ranged from soft (hardness +, K+, Ca2+, Mg2+, NO3-? and NH4+??(p Escherichia coli, Enterobacter, Streptococcus, Salmonella and Shigella spp, were identified in all the sampled waters, suggesting recent contamination of the sources by human or animal faeces. The sources were unfit for domestic uses and thus, exposed the local population to water borne diseases such as typhoid, diarrhoea and dysentery. Hence, home treatment methods such as chlorination, filtration, boiling and solar disinfection should be implemented prior to consumption.展开更多
紫外线及二氧化氯作为绿色消毒技术的代表,被越来越多地研究和使用,ClO_2消毒能够弥补UV不能提供持续消毒能力的不足,UV消毒作为ClO_2消毒的预处理工艺,能够降低后续消毒工艺的微生物负荷。通过试验对联合消毒效果进行了研究。试验表明...紫外线及二氧化氯作为绿色消毒技术的代表,被越来越多地研究和使用,ClO_2消毒能够弥补UV不能提供持续消毒能力的不足,UV消毒作为ClO_2消毒的预处理工艺,能够降低后续消毒工艺的微生物负荷。通过试验对联合消毒效果进行了研究。试验表明,在试验水质条件下,当紫外线剂量为60 m J/cm^2,二氧化氯投加量2 mg/L,反应时间15min时即可达到较好的消毒效果且成本较低,消毒后粪大肠菌在48 h内几乎不发生光复活。展开更多
Digestate, the product obtained after anaerobic digestion of organic waste for biogas production, is rich in plant nutrients and might be used to fertilize crops. Wheat(Triticum spp. L.) was fertilized with digestate,...Digestate, the product obtained after anaerobic digestion of organic waste for biogas production, is rich in plant nutrients and might be used to fertilize crops. Wheat(Triticum spp. L.) was fertilized with digestate, urea, or left unfertilized and cultivated in the greenhouse for 120 d. Emissions of greenhouse gasses(carbon dioxide(CO_2), methane(CH_4), and nitrous oxide(N_2O)) were monitored and plant growth characteristics were determined at harvest. The digestate was characterized for heavy metals, pathogens, and C and N mineralization potential in an aerobic incubation experiment. No Salmonella spp., Shigella spp., or viable eggs of helminths were detected in the digested pig slurry, but the number of faecal coliforms was as high as 3.6 × 10~4colony-forming units(CFU) g-^(1)dry digestate. The concentrations of heavy metals did not surpass the upper limits established by US Environmental Protection Agency(EPA). After 28 d, 17% of the organic C(436 g kg^(-1)dry digestate) and 8% of the organic N(6.92 g kg^(-1)dry digestate)were mineralized. Emissions of CO_2 and CH_4 were not significantly affected by fertilization in the wheat-cultivated soil, but digestate significantly increased the cumulative N_2O emission by 5 times compared to the urea-amended soil and 63 times compared to the uncultivated unfertilized soil. It could be concluded that digestate was nutrient rich and low in heavy metals and pathogens, and did not affect emissions of CH_4 and CO_2 when applied to a soil cultivated with wheat, but increased emission of N_2O.展开更多
文摘Universal access to safe water, whether at households or health centres, is central to achieving the sixth sustainable development goal by 2030. A hospital-based survey was conducted to screen for antimicrobial resistance among coliforms in samples collected from tap water (n = 54) at surgical wards in Gaza and to investigate the association with free residual chlorine and pH levels. Total coliforms (TC) were detected in 48.1% (26/54) of tested samples and FCs were detected in 25.9% (14/54). Free residual chlorine test ranged from zero to 0.2 mg/l (average: 0.08 mg/l), of which more than half of the samples (53.7%) 29/54 showed no free residual chlorine. The mean value of free residual chlorine in samples tested positive for growth on m-Endo (0.03) was lower than the mean for negative samples (0.14). The pH values were within the acceptable range (average: 7.6) and there was a statistically significant variation between the mean of pH values for samples tested positive on m-Endo (7.29) and that tested negative (7.84). Among coliform positive samples, 23.1% (6/26) had coliform isolates with resistance patterns. More than two-thirds of antimicrobial resistant (AMR) isolates were resistant to amikacin, ceftazidime, ceftriaxone, and imipenem. Moreover, 50% of the isolates were resistant to piperacillin-tazobactam. One-third (33.3%) of isolates were resistant to cefoxitin, and fosfomycin, 16.7% were resistant to ciprofloxacin, and nitrofurantoin. Intermediate resistance was shown in 16.7% of the isolates to cefoxitin and ciprofloxacin. The ESBL and carbapenem resistance genes detected in isolates were TEM (66.7%), NDM (33.3%), OXA (25%), blaCTXM (16.7%), and blaCTXM-3 (16.7%). The finding highlighted the level of contamination with AMR coliform in samples collected from tap water and pointed out the importance of managing water safety through identifying the main source of contamination, in addition to maintaining proper water disinfection at healthcare facilities for the patient, staff and environmental safety.
文摘This study is aimed at evaluating alternative designs of waste stabilization ponds (WSPs) and constructed wetlands (CWs) for Kaputiei Housing Estate consisting of 2000 low cost housing units in Kenya. The entire analysis was carried out by simulating the effectiveness and purification efficiencies of WSPs and CWs in terms of Biological Oxygen Demand (BOD) reduction and faecal coliform (FC) removal under different scenarios of water treatment systems that included Re-sizing of the initial sewage treatment system, optimizing the design of the initial system and design of hybrid system for the estate. The graphic comparison of the simulated parameters under different scenarios showed that a hybrid design that combines both the WSPs and CWS provides an effluent BOD of 20 mg/l and 195 FC per 100 ml that meets the standard effluent discharge that is acceptable for unrestricted crop irrigation and thus will be reused in the housing estate for kitchen gardening and agroforestry.
文摘A well surveillance study carried out in nine Divisional Secretariat Divisions on the west coast of Sri Lanka showed that 70.3% of 101 well sampling points were microbially contaminated with equal to, or greater than, faecal coliform grade C (11 - 100 cfu/100 mL). Due to the very vulnerable hydro-geological setting of the coastal sand, laterite and alluvium aquifers occurring in the study areas, the recommended safe separation distance between an on-site sanitation system and a well could not be achieved. Hence, a cardinal rule of well protection was observed to be broken at almost every well study site. The existing excreta disposal systems need to be improved or replaced with more efficient ones before the impact of other sanitary hazards at the well, and wellhead area, on the microbial quality of well water, can be determined and addressed. The published (WHO, 1997) sanitary survey forms for open dug wells and tube wells need to be modified in the context of the study areas described. Based on a comparison of three different statistical methods used to assess the relative significance of each sanitary hazard modification to the methodology for determining the sanitary hazard index (SHI) was prescribed.
文摘Concern for saline and microbial quality post-December 2004 tsunami, led to a field based surveillance study to systematically investigate the sanitary hazards which cause faecal contamination of groundwater. In seven islands, two duplicate sample sets, in two surveys, revealed that only 6.4% of the 173 well water samples (combining both surveys) satisfied the WHO Drinking Water Quality Guideline for 44°C thermo-tolerant (Faecal) Coliform (FC) indicator value (zero cfu/100 ml sample). Based on a combined risk analysis of Sanitary Hazard Score (SHS) and FC counts, more than 57.7% of the study wells were classified as at very high (FC: 100 to >1,000 cfu/100ml;and SHS: ≥ 9) microbial health risk. During this study, fundamental changes were made to the published generic sanitary inspection method (WHO, 1997) for identifying sanitary hazards, for its application in the extremely vulnerable hydro-geological setting of the Maldives. However, the most important hazard controlling the intensity of faecal contamination in the Maldives is the safe separation distance between a latrine seepage point and the well. It was demonstrated that, due to the prevailing hydro-geological conditions and the well and sanitation system densities, safe separation distance cannot be achieved. Consequently, septic tank effluent quality must be greatly improved.
文摘The rational for this study was to assess the microbial quality of fresh vegetables at the farm gate of the Water Works road vegetable farm at Gumbihini in the Tamale Metropolis. A total of thirty-six (36) vegetables comprising lettuce, amarantus and cabbages and eight (8) wastewater samples were collected at random and analysed for a period of four months, to assess the microbial contamination level. Samples were analysed for total coliforms, faecal coliforms, E. coli and helminthes eggs. All vegetables sampled during the study period recorded high levels of total and faecal coliform bacteria. Mean faecal coliforms for the various vegetables were as follows;lettuce 3.7 ± 0.5 CFU.g-1, amarantus 3.5 ± 0.6 CFU.g-1 and cabbage 3.1 ± 0.6 log CFU.g-1 fresh weight. FC levels were above the International Commission on Microbiological Specifications for Foods (ICMSF) recommended level of 3 log CFU.g-1 fresh weight. E. coli were recorded in lettuce (3.3 ± 0.6 log CFU.g-1 fresh weight) and amarantus (0.6 ± 0.1 log CFU.g-1 fresh weight) but not in cabbages. Lettuce generally recorded high levels of microbial contamination because of the large surface area occupied by its leaves. Two helminth eggs (Strongiloides stercoralis) were identified in lettuce while four (Ascaris lumbricoides) were identified in wastewater. Microbial loads recorded in wastewater were generally higher than that of vegetables. Since most of these vegetables are eaten fresh or slightly cooked, there is course for concern as public health will be adversely affected. Education of farmers and consumers on food safety has to be intensified to avert a possible outbreak.
文摘This study investigated the quality of ground water in Baba I, North-West Cameroon, in order to determine its suitability for domestic uses following World Health Organisation (WHO) guidelines. Inhabitants of this locality consume water from these sources without any prior treatment which can lead to health problems if the water sources are contaminated. Six water sources were sampled in November 2017, January, April and July 2018 and examined for organoleptic, physico-chemical and bacteriological parameters using standard methods. Results of organoleptic and physical parameters showed that most of the sources were within the WHO acceptable limits with pH varying from moderately acidic to weakly basic. Chemical properties revealed that all the analysed ions were found within the WHO guidelines and the water sources ranged from soft (hardness +, K+, Ca2+, Mg2+, NO3-? and NH4+??(p Escherichia coli, Enterobacter, Streptococcus, Salmonella and Shigella spp, were identified in all the sampled waters, suggesting recent contamination of the sources by human or animal faeces. The sources were unfit for domestic uses and thus, exposed the local population to water borne diseases such as typhoid, diarrhoea and dysentery. Hence, home treatment methods such as chlorination, filtration, boiling and solar disinfection should be implemented prior to consumption.
文摘紫外线及二氧化氯作为绿色消毒技术的代表,被越来越多地研究和使用,ClO_2消毒能够弥补UV不能提供持续消毒能力的不足,UV消毒作为ClO_2消毒的预处理工艺,能够降低后续消毒工艺的微生物负荷。通过试验对联合消毒效果进行了研究。试验表明,在试验水质条件下,当紫外线剂量为60 m J/cm^2,二氧化氯投加量2 mg/L,反应时间15min时即可达到较好的消毒效果且成本较低,消毒后粪大肠菌在48 h内几乎不发生光复活。
文摘Digestate, the product obtained after anaerobic digestion of organic waste for biogas production, is rich in plant nutrients and might be used to fertilize crops. Wheat(Triticum spp. L.) was fertilized with digestate, urea, or left unfertilized and cultivated in the greenhouse for 120 d. Emissions of greenhouse gasses(carbon dioxide(CO_2), methane(CH_4), and nitrous oxide(N_2O)) were monitored and plant growth characteristics were determined at harvest. The digestate was characterized for heavy metals, pathogens, and C and N mineralization potential in an aerobic incubation experiment. No Salmonella spp., Shigella spp., or viable eggs of helminths were detected in the digested pig slurry, but the number of faecal coliforms was as high as 3.6 × 10~4colony-forming units(CFU) g-^(1)dry digestate. The concentrations of heavy metals did not surpass the upper limits established by US Environmental Protection Agency(EPA). After 28 d, 17% of the organic C(436 g kg^(-1)dry digestate) and 8% of the organic N(6.92 g kg^(-1)dry digestate)were mineralized. Emissions of CO_2 and CH_4 were not significantly affected by fertilization in the wheat-cultivated soil, but digestate significantly increased the cumulative N_2O emission by 5 times compared to the urea-amended soil and 63 times compared to the uncultivated unfertilized soil. It could be concluded that digestate was nutrient rich and low in heavy metals and pathogens, and did not affect emissions of CH_4 and CO_2 when applied to a soil cultivated with wheat, but increased emission of N_2O.
