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Challenges in setting up a potable water supply system in a United Nations peacekeeping mission: The South Sudan experience
International Journal of Hygiene and Environmental Health 216 (2013) 88–90
Contents lists available at SciVerse ScienceDirect
International Journal of Hygiene and Environmental Health journal homepage: www.elsevier.com/locate/ijheh
Short communication
Challenges in setting up a potable water supply system in a United Nations peacekeeping mission: The South Sudan experience Aniruddha Hazra a,b,∗ a b
Indian Level – II Hospital, United Nations Mission in Sudan, Upper Nile State, South Sudan Department of Community Medicine, Armed Forces Medical College, Pune 411040, India
a r t i c l e
i n f o
Article history: Received 17 August 2011 Received in revised form 17 May 2012 Accepted 24 May 2012 Keywords: Drinking water United Nations Peacekeeping mission
a b s t r a c t Problem: A United Nations peacekeeping contingent was deployed in the conflict affected areas of South Sudan with inadequate environmental sanitation, lack of clean drinking water and a heightened risk of water-borne diseases. In the immediate post-deployment phase, the contingent-owned water purification system was pressed into service. However, laboratory analyses of processed water revealed its unsuitability for human consumption. Approach: A systematic, sanitary survey was conducted to identify the shortcomings in the water supply system’s ability to provide potable water. Under field conditions, the ‘H2 S method’ was used to detect faecal contamination of drinking water. Local setting: The raw water from the only available source, the White Nile River, was highly turbid and contaminated by intestinal and other pathogens due to an unprotected watershed. Water sterilizing powder was not readily available in the local area to replenish the existing stocks that had deteriorated during the long transit period from the troop contributing country. The water pipelines that had been laid along the ground, under water-logged conditions, were prone to microbial recontamination due to leakages in the network. Relevant changes: The critical evaluation of the water supply system and necessary modifications in the purification process, based upon locally available options, yielded safe drinking water. Lessons learnt: . Provision of safe drinking water in the mission area requires an in-depth analysis of prevailing conditions and appropriate planning in the pre-deployment phase. The chemicals for water purification should be procured through UN sources via a ‘letter of assist’ request from the troop contributor. © 2012 Elsevier GmbH. All rights reserved.
Introduction In a number of United Nations (UN) field missions, the Memorandum of Understanding between the troop contributing country (TCC) and the United Nations (as per the terms and conditions of a ‘wet-lease’ agreement) stipulates that providing the source of water is the responsibility of the UN whereas, the purification and further distribution of drinking water to troops is the responsibility of the TCC (UNDPKO, 2005). Therefore, the water purification and storage equipment, chemicals for water purification, spare parts
Abbreviations: UN, United Nations; TCC, troop contributing country; UNMIS, United Nations mission in Sudan; H2 S, hydrogen sulphide; NTU, nephalometric turbidity unit; RO, reverse osmosis; PVC, poly-vinyl chloride; UNOE, United Nations owned equipment; WSP, water safety plan. ∗ Correspondence address: Department of Community Medicine, Armed Forces Medical College, Pune 411040, India. Tel.: +91 9216223757; fax: +91 2026333065. E-mail address: [email protected] 1438-4639/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.ijheh.2012.05.008
and consumables have to be provisioned by the TCC and carried to the mission area by the peacekeeping contingent. In the recent past, an Indian military peacekeeping contingent was deployed as a part of United Nations Mission in Sudan (UNMIS) in the Upper Nile State of South Sudan. The region has an equatorial climate, with high temperatures, high rainfall and very high humidity. The White Nile River is the pre-dominant geographic feature of South Sudan and most of the settlements are clustered around this source of water. The region has clayey soil and during the rainy season there is a serious problem of water-logging and slush. The conflict affected areas of South Sudan with poor sanitation, lack of clean drinking water and overcrowded living conditions are at an increased risk of water-borne diseases like cholera (WHO, 2005). In the initial days of the post-deployment phase, packaged drinking water was supplied to the peacekeeping troops by the UN. In due course of time, contingent-owned water purification systems were pressed into service. However, the laboratory analyses of drinking water samples collected from various points of use showed that same were unfit for human consumption. It was
A. Hazra / International Journal of Hygiene and Environmental Health 216 (2013) 88–90
89
Table 1 Laboratory reports of water samples tested. Source of water sample
Bacteriological examination results (H2 S method)a
Turbiditya
Raw water from the source (White Nile River) Water sample from team – site A (after RO treatment) Water sample from team – site B (after RO treatment)
Presence of Salmonella, Citrobacter and Escherichia coli detected Presence of Citrobacter and Salmonella detected Presence of Escherichia coli detected
40 NTU NA NA
a As per WHO guidelines7 for drinking water quality: (a) E. coli or thermotolerant coliform bacteria must not be detectable in any 100 ml sample of water intended for drinking; (b) for effective terminal disinfection, turbidity should be ≤5 NTU.
recommended that the troops should be supplied with packaged drinking water until the shortcomings in the water supply system were redressed. The most effective means of consistently ensuring the safety of a drinking-water supply is through the use of a comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer and such an approach is known as a water safety plan (WSP) (WHO, 2011). Methods A systematic, sanitary survey was carried out by the author to evaluate the quality of water supply, as per the United States Environmental Protection Agency guidance manual (U.S. Environmental Protection Agency, 1999). The survey included the water supply system’s source, treatment, distribution network, storage and laboratory results of the bacteriological quality of water intended for drinking purposes, with the purpose of identifying the deficiencies that were adversely affecting the water system’s ability to provide safe drinking water. In the field laboratory in the mission area, the ‘hydrogen sulphide (H2 S) method’ test kit was used as an indicator of faecal contamination of drinking water (WHO, 2003; Gupta et al., 2008). Results The findings of the survey were as follows: (i) Risk assessment of the source of water. The source of collection of drinking water was the White Nile River. The water collection point was downstream of the local settlement with run off of surface waste water across the township as well as significant bather density and defaecation/urination on the banks of the river. The unprotected watershed also provided easy access to domestic cattle to the banks of the river. The water at this point was highly turbid (up to 40 NTU) and pathogens such as Salmonella, Citrobacter and Escherichia coli were detected by the H2 S method (see Table 1). The feasibility of collecting water from an alternate site, upstream of the settlement, was explored however; the approach was through a dirt road which was practically un-motorable in the rainy
season due to intense, water-logging and knee-deep slush. The problem was further compounded by the fact that there was a widespread threat of landmines in the region and only roads/tracks that had been cleared by the mine action group were certified fit for use by UN personnel. (ii) Problems with water treatment. The source of water had a very high load of microorganisms which was possibly clogging reverse osmosis (RO) membranes and causing bio-fouling. The RO Plant that was being used by the TCC had an activated carbon pre-filter. The same was being used on non-chlorinated water supplies. This provided a place for microorganisms to multiply and possibly led to increased bio-fouling of the RO membrane surface (Kneen et al., 2005). There was limited scope for chlorination of water due to the non-availability of fresh water sterilizing powder/chlorine gas in the area of deployment. The existing stocks of bleaching powder with the TCC had become crystalline due to exposure to heat and humidity in the long period in transit from the country of origin to the mission area. The same had very little available chlorine to be effective in disinfection of water. (iii) Risk assessment of the water distribution network. The water was distributed from the water purification plant to the drinking water storage tanks through flexible PVC pipes. These pipes were laid on the ground through water-logged areas and had ad-hoc joints that were prone to leakages. In the system of intermittent water supply, negative pressures developed inside the pipes when water was not being pumped through them. This probably led to siphoning of contaminated water from the surrounding area into the water supply system through the leaky joints in the PVC pipes. (iv) Problems with RO processed water storage. The RO processed water entered the storage tank by means of flexible PVC pipe through an open hatch on top. In the absence of proper screening of this opening there was a likelihood of recontamination of water at this point by dust, rain, insects, bird droppings and microorganisms. In the absence of any disinfectant residual in the water, the pathogens entering the system at this point due to recontamination could not be dealt with. The design of the polymer water storage tanks with a single hatch on top was not amenable to periodic cleaning of internal surfaces as there was no outlet at the bottom.
Fig. 1. Schematic representation of the modified potable water supply used in a UN field mission.
90
A. Hazra / International Journal of Hygiene and Environmental Health 216 (2013) 88–90
Relevant changes The main shortcomings in the water supply system that needed to be rectified were: (i) to find a suitable site or source for collection of raw water; (ii) to reduce the turbidity of water prior to filtration; (iii) to chlorinate the water; (iv) to provide a water-tight network of distribution pipes; (v) to modify the design of processed water storage tanks. A brief description of the relevant changes that were made to improve the quality of drinking water (Fig. 1) is presented in the succeeding paragraphs. Under the prevailing circumstances, it was not straight away feasible to find an alternate site for collection of water from the White Nile River, in the vicinity of the camp-site. Therefore, it was recommended to the UN Sector Engineer to explore the possibility of drilling deep bore wells, sited away from potential sources of contamination. Since required spares and consumables to augment the water supply system were not available in the local setting, fresh stocks of alum, bleaching powder and additional water pumps were requisitioned and shipped on an urgent basis from the TCC. Other essential stores like rigid PVC pipes, joints and collapsible water storage tanks were made available from the sector engineering stores [UN owned equipment (UNOE)]. Provision was made for alum flocculation of river water and further sedimentation in the collapsible water tanks. The supernatant water from sedimentation tanks was pumped into another set of interconnected, polymer water storage tanks and calculated dose of bleaching powder solution was added for chlorination. After a contact period of one hour, the water was pumped into the reverse osmosis plant, equipped with an activated carbon pre-filter to eliminate the risk of free chlorine damage to the semi-permeable RO membrane. A network of water-tight, rigid and fixed PVC pipes (raised over ground) was laid from point of entry to the intended points of use of drinking water. The RO plant was also relocated closer to the intended points of use. Special modifications were also made to the processed water storage tanks, to include an inlet (separate from the top hatch) and two outlets viz. one for the water dispensing tap and another at the bottom of tank to facilitate run-off of water used for periodic cleaning of the tanks. Conclusion The critical evaluation of the water supply system and the relevant modifications in the purification process facilitated the availability of safe drinking water to the UN peacekeeping contingent, as was substantiated by subsequent laboratory analyses of water samples. However, this vital aspect requires an in-depth analysis of prevailing conditions and appropriate planning in the
pre-deployment phase. It is also recommended that the chemicals for water purification such as alum, bleaching powder, chlorine tablets etc. should be procured through UN sources (as is the case with fuel and food items) via a ‘letter of assist’ request from the troop contributor (UNDPKO, 2005). Safe drinking water is a basic human need and a prerequisite for ensuring optimal health of peacekeeping personnel.
Summary of the main lessons learnt. • It may not always be possible to select a suitable source of drinking water or utilize a standard method for water treatment in conflict affected areas due to the limitations imposed by the prevailing conditions. • In order to ensure availability of safe drinking water in UN peacekeeping missions, it is imperative to carry out an indepth analysis of the local setting along with meticulous planning for provisioning of appropriate water purification equipment and stores in the pre-deployment phase. • The chemicals for water purification, being an essential requirement in the mission area, should be procured through UN sources (as is the case with fuel and food items) via a “letter of assist” request from the TCC.
References UNDPKO (United Nations Department of Peacekeeping Operations), 2005. Manual on policies and procedures concerning the reimbursement and control of contingent-owned equipment of troop/police contributors participating in peacekeeping missions (COE Manual). United Nations document No. A/C.5/60/26. WHO (World Health Organisation), 2005. Infectious Disease Risk Profile for Sudan (accessed 15.01.11) http://www.emro.who.int/sudan/pdf/ InfectiousDiseaseRiskProfileforSudan.pdf. U.S. Environmental Protection Agency, 1999. Guidance Manual for Conducting Sanitary Surveys of Public Water Systems—Surface Water and Ground Water Under the Direct Influence (GWUDI). Office of Water, Washington, DC, EPA 815-R-99016. WHO (World Health Organisation), 2003. Emerging Issues in Water and Infectious Disease (accessed 02.02.11) http://www.who.int/water sanitation health/emerging/emerging.pdf. Gupta, S.K., et al., 2008. Usefulness of the hydrogen sulfide test for assessment of water quality in Bangladesh. J. Appl. Microbiol. 104 (2), 388–395. Kneen, B., Lemley, A., Wagenet, L., 2005. Reverse Osmosis Treatment of Drinking Water (Fact Sheet 4, updated November 2005). Cornell Cooperative Extension, New York State College of Human Ecology, New York (accessed 15.01.11) http://waterquality.cce.cornell.edu/publications/CCEWQ04-ReverseOsmosisWtrTrt.pdf. WHO (World Health Organisation), 2011. Guidelines for Drinking-Water Quality, 4th ed.
Contents lists available at SciVerse ScienceDirect
International Journal of Hygiene and Environmental Health journal homepage: www.elsevier.com/locate/ijheh
Short communication
Challenges in setting up a potable water supply system in a United Nations peacekeeping mission: The South Sudan experience Aniruddha Hazra a,b,∗ a b
Indian Level – II Hospital, United Nations Mission in Sudan, Upper Nile State, South Sudan Department of Community Medicine, Armed Forces Medical College, Pune 411040, India
a r t i c l e
i n f o
Article history: Received 17 August 2011 Received in revised form 17 May 2012 Accepted 24 May 2012 Keywords: Drinking water United Nations Peacekeeping mission
a b s t r a c t Problem: A United Nations peacekeeping contingent was deployed in the conflict affected areas of South Sudan with inadequate environmental sanitation, lack of clean drinking water and a heightened risk of water-borne diseases. In the immediate post-deployment phase, the contingent-owned water purification system was pressed into service. However, laboratory analyses of processed water revealed its unsuitability for human consumption. Approach: A systematic, sanitary survey was conducted to identify the shortcomings in the water supply system’s ability to provide potable water. Under field conditions, the ‘H2 S method’ was used to detect faecal contamination of drinking water. Local setting: The raw water from the only available source, the White Nile River, was highly turbid and contaminated by intestinal and other pathogens due to an unprotected watershed. Water sterilizing powder was not readily available in the local area to replenish the existing stocks that had deteriorated during the long transit period from the troop contributing country. The water pipelines that had been laid along the ground, under water-logged conditions, were prone to microbial recontamination due to leakages in the network. Relevant changes: The critical evaluation of the water supply system and necessary modifications in the purification process, based upon locally available options, yielded safe drinking water. Lessons learnt: . Provision of safe drinking water in the mission area requires an in-depth analysis of prevailing conditions and appropriate planning in the pre-deployment phase. The chemicals for water purification should be procured through UN sources via a ‘letter of assist’ request from the troop contributor. © 2012 Elsevier GmbH. All rights reserved.
Introduction In a number of United Nations (UN) field missions, the Memorandum of Understanding between the troop contributing country (TCC) and the United Nations (as per the terms and conditions of a ‘wet-lease’ agreement) stipulates that providing the source of water is the responsibility of the UN whereas, the purification and further distribution of drinking water to troops is the responsibility of the TCC (UNDPKO, 2005). Therefore, the water purification and storage equipment, chemicals for water purification, spare parts
Abbreviations: UN, United Nations; TCC, troop contributing country; UNMIS, United Nations mission in Sudan; H2 S, hydrogen sulphide; NTU, nephalometric turbidity unit; RO, reverse osmosis; PVC, poly-vinyl chloride; UNOE, United Nations owned equipment; WSP, water safety plan. ∗ Correspondence address: Department of Community Medicine, Armed Forces Medical College, Pune 411040, India. Tel.: +91 9216223757; fax: +91 2026333065. E-mail address: [email protected] 1438-4639/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.ijheh.2012.05.008
and consumables have to be provisioned by the TCC and carried to the mission area by the peacekeeping contingent. In the recent past, an Indian military peacekeeping contingent was deployed as a part of United Nations Mission in Sudan (UNMIS) in the Upper Nile State of South Sudan. The region has an equatorial climate, with high temperatures, high rainfall and very high humidity. The White Nile River is the pre-dominant geographic feature of South Sudan and most of the settlements are clustered around this source of water. The region has clayey soil and during the rainy season there is a serious problem of water-logging and slush. The conflict affected areas of South Sudan with poor sanitation, lack of clean drinking water and overcrowded living conditions are at an increased risk of water-borne diseases like cholera (WHO, 2005). In the initial days of the post-deployment phase, packaged drinking water was supplied to the peacekeeping troops by the UN. In due course of time, contingent-owned water purification systems were pressed into service. However, the laboratory analyses of drinking water samples collected from various points of use showed that same were unfit for human consumption. It was
A. Hazra / International Journal of Hygiene and Environmental Health 216 (2013) 88–90
89
Table 1 Laboratory reports of water samples tested. Source of water sample
Bacteriological examination results (H2 S method)a
Turbiditya
Raw water from the source (White Nile River) Water sample from team – site A (after RO treatment) Water sample from team – site B (after RO treatment)
Presence of Salmonella, Citrobacter and Escherichia coli detected Presence of Citrobacter and Salmonella detected Presence of Escherichia coli detected
40 NTU NA NA
a As per WHO guidelines7 for drinking water quality: (a) E. coli or thermotolerant coliform bacteria must not be detectable in any 100 ml sample of water intended for drinking; (b) for effective terminal disinfection, turbidity should be ≤5 NTU.
recommended that the troops should be supplied with packaged drinking water until the shortcomings in the water supply system were redressed. The most effective means of consistently ensuring the safety of a drinking-water supply is through the use of a comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer and such an approach is known as a water safety plan (WSP) (WHO, 2011). Methods A systematic, sanitary survey was carried out by the author to evaluate the quality of water supply, as per the United States Environmental Protection Agency guidance manual (U.S. Environmental Protection Agency, 1999). The survey included the water supply system’s source, treatment, distribution network, storage and laboratory results of the bacteriological quality of water intended for drinking purposes, with the purpose of identifying the deficiencies that were adversely affecting the water system’s ability to provide safe drinking water. In the field laboratory in the mission area, the ‘hydrogen sulphide (H2 S) method’ test kit was used as an indicator of faecal contamination of drinking water (WHO, 2003; Gupta et al., 2008). Results The findings of the survey were as follows: (i) Risk assessment of the source of water. The source of collection of drinking water was the White Nile River. The water collection point was downstream of the local settlement with run off of surface waste water across the township as well as significant bather density and defaecation/urination on the banks of the river. The unprotected watershed also provided easy access to domestic cattle to the banks of the river. The water at this point was highly turbid (up to 40 NTU) and pathogens such as Salmonella, Citrobacter and Escherichia coli were detected by the H2 S method (see Table 1). The feasibility of collecting water from an alternate site, upstream of the settlement, was explored however; the approach was through a dirt road which was practically un-motorable in the rainy
season due to intense, water-logging and knee-deep slush. The problem was further compounded by the fact that there was a widespread threat of landmines in the region and only roads/tracks that had been cleared by the mine action group were certified fit for use by UN personnel. (ii) Problems with water treatment. The source of water had a very high load of microorganisms which was possibly clogging reverse osmosis (RO) membranes and causing bio-fouling. The RO Plant that was being used by the TCC had an activated carbon pre-filter. The same was being used on non-chlorinated water supplies. This provided a place for microorganisms to multiply and possibly led to increased bio-fouling of the RO membrane surface (Kneen et al., 2005). There was limited scope for chlorination of water due to the non-availability of fresh water sterilizing powder/chlorine gas in the area of deployment. The existing stocks of bleaching powder with the TCC had become crystalline due to exposure to heat and humidity in the long period in transit from the country of origin to the mission area. The same had very little available chlorine to be effective in disinfection of water. (iii) Risk assessment of the water distribution network. The water was distributed from the water purification plant to the drinking water storage tanks through flexible PVC pipes. These pipes were laid on the ground through water-logged areas and had ad-hoc joints that were prone to leakages. In the system of intermittent water supply, negative pressures developed inside the pipes when water was not being pumped through them. This probably led to siphoning of contaminated water from the surrounding area into the water supply system through the leaky joints in the PVC pipes. (iv) Problems with RO processed water storage. The RO processed water entered the storage tank by means of flexible PVC pipe through an open hatch on top. In the absence of proper screening of this opening there was a likelihood of recontamination of water at this point by dust, rain, insects, bird droppings and microorganisms. In the absence of any disinfectant residual in the water, the pathogens entering the system at this point due to recontamination could not be dealt with. The design of the polymer water storage tanks with a single hatch on top was not amenable to periodic cleaning of internal surfaces as there was no outlet at the bottom.
Fig. 1. Schematic representation of the modified potable water supply used in a UN field mission.
90
A. Hazra / International Journal of Hygiene and Environmental Health 216 (2013) 88–90
Relevant changes The main shortcomings in the water supply system that needed to be rectified were: (i) to find a suitable site or source for collection of raw water; (ii) to reduce the turbidity of water prior to filtration; (iii) to chlorinate the water; (iv) to provide a water-tight network of distribution pipes; (v) to modify the design of processed water storage tanks. A brief description of the relevant changes that were made to improve the quality of drinking water (Fig. 1) is presented in the succeeding paragraphs. Under the prevailing circumstances, it was not straight away feasible to find an alternate site for collection of water from the White Nile River, in the vicinity of the camp-site. Therefore, it was recommended to the UN Sector Engineer to explore the possibility of drilling deep bore wells, sited away from potential sources of contamination. Since required spares and consumables to augment the water supply system were not available in the local setting, fresh stocks of alum, bleaching powder and additional water pumps were requisitioned and shipped on an urgent basis from the TCC. Other essential stores like rigid PVC pipes, joints and collapsible water storage tanks were made available from the sector engineering stores [UN owned equipment (UNOE)]. Provision was made for alum flocculation of river water and further sedimentation in the collapsible water tanks. The supernatant water from sedimentation tanks was pumped into another set of interconnected, polymer water storage tanks and calculated dose of bleaching powder solution was added for chlorination. After a contact period of one hour, the water was pumped into the reverse osmosis plant, equipped with an activated carbon pre-filter to eliminate the risk of free chlorine damage to the semi-permeable RO membrane. A network of water-tight, rigid and fixed PVC pipes (raised over ground) was laid from point of entry to the intended points of use of drinking water. The RO plant was also relocated closer to the intended points of use. Special modifications were also made to the processed water storage tanks, to include an inlet (separate from the top hatch) and two outlets viz. one for the water dispensing tap and another at the bottom of tank to facilitate run-off of water used for periodic cleaning of the tanks. Conclusion The critical evaluation of the water supply system and the relevant modifications in the purification process facilitated the availability of safe drinking water to the UN peacekeeping contingent, as was substantiated by subsequent laboratory analyses of water samples. However, this vital aspect requires an in-depth analysis of prevailing conditions and appropriate planning in the
pre-deployment phase. It is also recommended that the chemicals for water purification such as alum, bleaching powder, chlorine tablets etc. should be procured through UN sources (as is the case with fuel and food items) via a ‘letter of assist’ request from the troop contributor (UNDPKO, 2005). Safe drinking water is a basic human need and a prerequisite for ensuring optimal health of peacekeeping personnel.
Summary of the main lessons learnt. • It may not always be possible to select a suitable source of drinking water or utilize a standard method for water treatment in conflict affected areas due to the limitations imposed by the prevailing conditions. • In order to ensure availability of safe drinking water in UN peacekeeping missions, it is imperative to carry out an indepth analysis of the local setting along with meticulous planning for provisioning of appropriate water purification equipment and stores in the pre-deployment phase. • The chemicals for water purification, being an essential requirement in the mission area, should be procured through UN sources (as is the case with fuel and food items) via a “letter of assist” request from the TCC.
References UNDPKO (United Nations Department of Peacekeeping Operations), 2005. Manual on policies and procedures concerning the reimbursement and control of contingent-owned equipment of troop/police contributors participating in peacekeeping missions (COE Manual). United Nations document No. A/C.5/60/26. WHO (World Health Organisation), 2005. Infectious Disease Risk Profile for Sudan (accessed 15.01.11) http://www.emro.who.int/sudan/pdf/ InfectiousDiseaseRiskProfileforSudan.pdf. U.S. Environmental Protection Agency, 1999. Guidance Manual for Conducting Sanitary Surveys of Public Water Systems—Surface Water and Ground Water Under the Direct Influence (GWUDI). Office of Water, Washington, DC, EPA 815-R-99016. WHO (World Health Organisation), 2003. Emerging Issues in Water and Infectious Disease (accessed 02.02.11) http://www.who.int/water sanitation health/emerging/emerging.pdf. Gupta, S.K., et al., 2008. Usefulness of the hydrogen sulfide test for assessment of water quality in Bangladesh. J. Appl. Microbiol. 104 (2), 388–395. Kneen, B., Lemley, A., Wagenet, L., 2005. Reverse Osmosis Treatment of Drinking Water (Fact Sheet 4, updated November 2005). Cornell Cooperative Extension, New York State College of Human Ecology, New York (accessed 15.01.11) http://waterquality.cce.cornell.edu/publications/CCEWQ04-ReverseOsmosisWtrTrt.pdf. WHO (World Health Organisation), 2011. Guidelines for Drinking-Water Quality, 4th ed.