Agnes Mokhosi

Bloodless Dzwairo

Environmental Economics

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“Microbiological water quality along Vaal Gamagara’s potable water distributionsystem”AUTHORSAgnes MokhosiBloodless Dzwairo http://orcid.org/0000-0002-0127-2978ResearcherID: L-3155-2015ARTICLE INFOAgnes Mokhosi and Bloodless Dzwairo (2015). Microbiological water qualityalong Vaal Gamagara’s potable water distribution system. EnvironmentalEconomics, 6(1-si), 152-158RELEASED ON Friday, 05 June 2015JOURNAL "Environmental Economics"FOUNDER LLC “Consulting Publishing Company “Business Perspectives”NUMBER OF REFERENCES0NUMBER OF FIGURES0NUMBER OF TABLES0© The author(s) 2021. This publication is an open access article.businessperspectives.orgEnvironmental Economics, Volume 6, Issue 1, 2015  152Agnes Mokhosi (South Africa), Bloodless Dzwairo (South Africa) Microbiological water quality along Vaal Gamagara’s potable  water distribution system Abstract Safe drinking water is essential to all life forms. Thus analysis for microbiological parameters is critical as this assists in declaring the fitness of potable water for human consumption, among other sustainable and “green uses”. The aim of this paper is to investigate the microbiological quality of potable water along Vaal Gamagara Water Treatment Plant’s (VGWTP) distribution system. A total of 10 samples were collected weekly along the system. The samples were col-lected from January to December 2013 in order to analyze for Escherichia coli (E.coli), total coliforms (TC) and Hete-rotrophic plate counts (HPC). The results showed that only 0.1% and 0.4% of samples analyzed were positive for E. coli and total coliforms, respectively. However, HPC results showed that 40% of the samples analyzed from June to December 2013 had higher counts than the recommended standard limit. The chlorine residual showed an increase from June to December 2013. An assessment of the results indicated that the integrity of the system was compromised for the research period. Water quality failures in a distribution system are unacceptable because they threaten human health and sometimes result in loss of life. Thus the assessment called for an urgent need to boost chlorine residual especially at points further away from the treatment plant. This was envisaged to provide a safety net for microbial compliance while the system was critically and continuously monitored, and further investigations were performed. Studies on chlorine decay were recommended as a priority in order to optimize disinfection and maintain good quality drinking water throughout the system.  Keywords: Escherichia coli, chlorine residual, Heterotrophic plate Counts, microbiological parameters, total coli-forms. JEL Classification: Q53, Q56, Q57.  Introduction © Access to potable water is a worldwide challenge be-cause the raw water sources are impacted to various degrees, resulting in variable cost inputs towards treat-ing the raw water to acceptable standards.  This has an economic implication which, going forward, has an impact on the global economy down to local context. Nhamo and Nhamo (2014) noted that the term “green economy”, which is also used interchangeably with “green growth”, gained prominence in 2008 after the world suffered a financial collapse. For example, in the Southern African Development Community (SADC), more sustainable ways to exploit natural resources have since been called for amid a backdrop of poverty and hunger.  SADC advocates for policies and processes to support and promote sustainable production and consumption of resources, the major of which is water. Thus the region inevitably also subscribes to the green economy drive in order to promote local production, consump-tion, and efficient use of water (Letsoalo, 2013), among other natural resources. Sustainable use of water in terms of its quality and quantity assures avail-ability for current and future generations.                                                       © Agnes Mokhosi, Bloodless Dzwairo, 2015. Agnes Mokhosi, B.Tech., Postgraduate Masters Student, Department of Operations and Quality, Faculty of Management Sciences, Durban University of Technology, South Africa. Bloodless Dzwairo, D.Tech., Research Fellow, Institute of Systems Science, Durban University of Technology, South Africa. Since water is a basic component of sustainable living and socio-economic development, practices that help to conserve its quality and quantity thus also promote green development in the various sec-tors where it is used. Water plays an important role towards sustaining development and eliminating poverty and it also subsidizes 60% towards agricul-ture and irrigation in the South African economy (Government, 2015). “Investment in safe drinking water and sanitation is a path to economic growth” (htttp://www.unep.org/greeneconomy).  The supply of chemically and microbiologically safe potable water to communities is of major and signi-ficant importance. Compromised microbiological quality of potable water poses a health risk to all life forms and is a cost to water utilities (Abdolmajid, 2014; Dzwairo, 2005; WHO, 2011; DWAF, 1996; Dzwairo et al., 2010). In South Africa there is a challenge of deterioration of potable water quality during transportation through the distribution sys-tem and also during storage. Usually the final qua-lity of drinking water cannot be secured after the water has been distributed to the storage facilities and consumers (Momba et al., 2000). Quality of drinking water that complies with the South African National Standard (SANS) 241 (SABS, 2011) is considered fit for human consumption and is not expected to pose any health risks to the consumers. According to this standard the recommended limits for TC is 10 counts/100 mL, for HPC is 1000 counts/100 mL and E. coli should not be detected. Environmental Economics, Volume 6, Issue 1, 2015  153It is very important to test for E. coli in potable wa-ter since it is an indication of faecal contamination (Abdolmajid, 2014; WHO, 2011; Lewis et al., 1980; Graham and Polizzotto, 2013; Dzwairo et al., 2006). Literature indicates that HPC is used as an indicator for monitoring of potable water for microbiological quality, in the distribution system (Pavlon et al., 2004; Francisque et al., 2009; Chowdhury, 2012). Other studies have shown that HPC measurements are used to assess effectiveness of the water treat-ment processes (Bartram et al., 2004; Chowdhury, 2012), specifically performance of the final water disinfection process (Francisque et al., 2009; Chowdhury, 2012). Worldwide, countries utilize the HPC method to monitor the microbiological quality of potable water along the distribution system (Siebel et al., 2008). “It is very important to control HPC bacteria in a water distribution systems in order to minimise human expo-sure to pathogenic microorganisms” (Chowdhury, 2012). If the water leaving the water treatment plant after the treatment process has high HPC above the recommended limit, it means that the distribution sys-tem has high levels of HPC. If potable water from the water treatment plant is distributed with acceptable levels of HPC but the levels increased in the distribu-tion system, this shows that there was/is recontamina-tion in the distribution system (Robertson, W. and Brooks, T., 2003). High HPC levels indicate a deteri-oration of microbiological potable water quality, bac-terial regrowth and potential formation of biofilms (Bartram et al., 2002). The microbiological quality of portable water de-pends on factors such as chlorine residual. Chlorina-tion is a popular disinfection method that is used in some developed and most developing countries. The chlorine residual is used to reduce regrowth of mi-croorganisms and to maintain microbiological quali-ty in the distribution system. Water distribution systems that are not protected enough may result in breakdown due to waterborne diseases (WHO, 2011). It is reported that about 3.4 million people died every year due to water borne diseases (Chowdhury, 2012) while a large number of these deaths were as a result of drinking faecallycontami-nated water (Dzwairo et al., 2006). Thus this study looked at the temporal and spatial variation of the aforementioned parameters with the view of concluding on trends of microbiological quality of potable water in the VGWT system for the year 2013. The results were meant to contribute towards an in-depth assessment of the integrity of the distribution system. 1. Study area The VGWTP is operated by Sedibeng Water Board and is situated at Delportshoop in the Northern Cape Province. Fig. 1 shows the Northern Cape Province in South Africa. The study area covers Delportshoop near Barkly West (VG02 in Fig. 2) to Black Rock, with a total pipeline length of approximately 370 km. The fur-thest point in the distribution system is at Blackrock (VG13) (Fig. 2).  Fig. 1. Map showing Northern Cape Province Disinfection occurs at the treatment works (VG02) and at Beeshoek (VG05) near Postmansburg that is lo-cated 150 km away from the water treatment works. Environmental Economics, Volume 6, Issue 1, 2015  154 Fig. 2. Vaal Gamagara Sedibeng Water Board sampling points 2. Methods and materials 2.1. Sampling. A total of 10 distribution samples were collected from Vaal Gamagara distribution sys-tem. The samples were collected on a weekly basis from January to December 2013 for the analyses of microbiological parameters: E.coli, TC and HPC. The samples were collected using 500 mL sterile bottles. The sampling procedure was followed as described in the Standard Methods for the Examination of Water and Wastewater (APHA, 2012). 2.2. Analytical measurements. The DPD Colorimet-ric method (4500-CI G) was used to measure free residual chlorine on site during sampling (APHA, 2012). A sample cell was filled with 10 mL of potable water. The DPD chlorine reagent was added to the sample and the chlorine residual was measured using HACH Pocket Colorimeter II. The pour plate method 9215B was used in the laboratory for the analyses of HPC (APHA, 2012). Some 1 mL of a sample was   pipetted into a petri dish and the yeast extract agar was added to the sample. Duplicate plates were incubated for 44 to 48 hours at 36 ± 1oC. The results were ex-pressed in CFU/mL.  The TC and E. coli were analyzed using IDEXX Quanti-Tray Standard Method of 1994. A 100 mL volume of water was measured into a bottle and the dehydrated media was added to it. After the powd-er dissolved, the sample containing the media was dispensed into a multi-well sachet (Quanti-Tray), which was heat-sealed using a Quanti Tray sealer. Following incubation at 36°C (± 1°C) for 18-22 hours, the number of yellow wells and the number of wells that fluoresced were counted. The results were expressed as counts/100 mL. 3. Results and discussion Fig. 3 shows the results of E. coli over a period of 12 months. The results indicate that only 0.1% of samples analyzed were positive for E. coli.  Fig. 3. E. coli results for January to December 2013 Environmental Economics, Volume 6, Issue 1, 2015  155Figure 4 illustrates the results of TC along a period of 12 months. The results showed that the TC above recommended standard limit were detected in only 0.4% of samples analyzed.  Fig. 4. Total coliform results for January to December 2013 Figure 5 shows the results of HPC for a period of 12 months. The results show that from January to May 2013, there were occasional HPC failures in the distribution. However, between June and De-cember 2013, HPC failures (not complying with the standard limits as prescribed in SANS 241, 2011), became regular. From June to December 2013, the concentration of HPC was above 1000 CFU/mL in 40% of the samples analyzed.  Fig. 5. Heterotrophic plate count results for January to December 2013 Figure 6 shows the results of residual chlorine for a period of 12 months. The results show that from January to May 2013, the chlorine residual was < 0.1 mg/L for most of the sampling points except for the initial treated water at VG02. From June to De-cember 2013, the chlorine residuals increased but the HPC still failed. The results indicate that inefficient disinfection is one of the factors that contribute to high HPC in the distribution system, but in this case other factors would require further investigation. Environmental Economics, Volume 6, Issue 1, 2015  156 Fig. 6. Residual chlorine results for January to December 2013 Figure 7 shows the results of HPC versus chlorine for VG02 (which is the initial sampling point at the plant, for final treated water). The results show good residual chlorine throughout the year and HPC was not de-tected in most cases. The highest HPC result detected was 50 CFU/mL with chlorine residual of <1.0 mg/L.  Fig. 7. Graph of chlorine and HPC for VG02 Figure 8 shows the results of residual chlorine versus HPC for VG13, which is the furthest point from the treatment plant, in the distribution sys-tem. The results show that residual chlorine from January to May 2013 was as low as 0.01 mg/L while the HPC were always below 1000 CFU/mL, which is the standard limit. Starting June 2013 to December 2013, the residual chlorine improved, but HPC was >5700 CFU/mL in most cases. The value >5700 CFU/mL was statically changed to 5701 for analysis purposes, as described in Dzwairo et al. (2011).  Fig. 8. Graph of chlorine and HPC for VG13 Environmental Economics, Volume 6, Issue 1, 2015  157Conclusions The E. coli and TC results showed very low percen-tages, which means that there was no fecal contami-nation from the samples that were collected from Vaal Gamagara distribution system. The HPC results showed a trend of failures (Figure 5, 7) starting June 2013 to December 2013 as a result of the residual chlorine which fluctuated during that pe-riod. Further investigation is in progress in order to: 1. identify possible contributing factors for the HPC failures in a section of VGWTP’s long dis-tribution network; 2. assess the chlorine decay in a section of the water board’s long distribution network;  3. investigate and test an alternative disinfection protocol that could sustain the integrity of an identified section of VGWTP’s long distribution network.  An assessment of the results indicated that the integrity of the system was compromised for the research pe-riod. Water quality failures in a distribution system are unacceptable because they threaten human health and sometimes result in loss of life. Thus the assessment   called for an urgent need to boost chlorine residual especially at points further away from the treatment plant. This was envisaged to provide a safety net for microbial compliance while the system was critically and continuously monitored, and further investigations were performed. Studies on chlorine decay were re-commended as a priority in order to optimize disinfec-tion and maintain good quality drinking water throughout the system, a fundamental concept of green production, distribution and use of good quality water. It is essential to supply good quality potable water in order to improve human well-being and to protect imminent re-generation of environmental risks and ecological scarcities. Acknowledgements The authors would like to sincerely acknowledge Durban University of Technology for hosting and co-funding the Masters degree, which formed a basis for the paper. Dr Bloodless Dzwairo is ac-knowledged for both co-authoring and supervising the Masters student. Sedibeng Water Board is thanked immensely for allocating a bursary for the student’s Masters degree and for providing very valuable data. References 1. Abdolmajid, F. (2014). A Comparison of the Bacteriological Quality of Drinking Water for the rural area of Hooreh and Arjnk, Iran, Resources and Environment, 4, pp. 215-219. 2. Apha, A., WEF 2012. Standard methods for the examination of water and wastewater, Washington, DC. 3. Bartram, J., Cotruvo, J., Exner, M., Fricker, C. & Glasmacher, A. (2002). Heterotrophic plate count measurement in drinking water safety management: Report of an Expert Meeting Geneva, 24-25 April, 2002, International Journal of Food Microbiology, 92, pp. 241-247. 4. Chowdhury, S. (2012). Heterotrophic bacteria in drinking water distribution system: a review, Environmental monitoring and assessment, 184, pp. 6087-6137. 5. DWAF (1996). South African Water Quality Guidelines: Volume 1: Domestic Water Use. In: HOLMES, S. (ed.) SANS. Pretoria, South Africa: Department of Water Affairs and Forestry (DWAF). 6. Dzwairo, B. (2005). Assessment of the Impacts of Pit Latrines on Groundwater Quality in Rural Areas: a case study from Marondera District, Zimbabwe. MSc Integrated Water Resources Management MSc thesis, University of Zimbabwe. 7. Dzwairo, B., Hoko, Z., Love, D. & Guzha, E. (2006). Assessment of the impacts of pit latrines on groundwater quality in rural areas: A case study from Marondera district, Zimbabwe, Physics and Chemistry of the Earth, Parts A/B/C, 31, pp. 779-788. 8. Dzwairo, B., Ochieng, G.M., Letsoalo, M.E. & Otieno, F.A. (2011). Data Reduction for Water Quality Modelling, Vaal Basin. In: Leite, E.P. (ed.) Scientific and Engineering Applications Using Matlab. Croatia: Intech. 9. Dzwairo, B., Otieno, F.A.O. & Ochieng’, G.M. (2010). Incorporating surface raw water quality into the cost chain for water services: Vaal catchment, South Africa, Research Journal of Chemistry and Environment, 14, pp. 29-35. 10. Francisque, A., Rodriguez, M.J., Miranda-Moreno, L.F., Sadiq, R. & Proulx, F. (2009). Modeling of heterotrophic bacteria counts in a water distribution system, Water Research, 43, pp. 1075-1087. 11. Graham, J.P. & Polizzotto, M.L. (2013). Pit Latrines and Their Impacts on Groundwater Quality: A Systematic Review, Environmental Health Perspectives, 121, p. 521. 12. Letsoalo, A. (2013). Limpopo Green Economy Plan Including Provincial Climate Change Response. Polokwane, South Africa: Department of Economic Development, Environment and Tourism. 13. Lewis, W., Foster, S.D. & Draser, B.S. (1980). The risk of groundwater pollution by on-site sanitation in develo-ping countries: A literature review. 14. Momba, M.N.B., Kfir, R., Venter, S.N. & Cloete, T.E. (2000). An overview of biofilm formation in distribution systems audits impact on the deterioration of water quality, Water SA, 26 (1), pp. 55-66. 15. Nhamo, S. and Nhamo, G. (2014). Mainstreaming green economy into sustainable development policy frame-works in SADC, Environmental Economics, 5 (1), pp. 6-17. Environmental Economics, Volume 6, Issue 1, 2015  15816. Pavlon, D., De Wet, C.M.E., Grabow, W.O.K. & Ehlers, M.M. (2004). Potentially pathogenic features of hetero-trophic plate count bacteria isolated from treated and untreated drinking water, International Journal of Food Mi-crobiology, 92, pp. 275-287. 17. Robertson, W. & Brooks, T. (2003). The role of HPC in managing the treatment and distribution of drinking-water.  18. SABS (2011). South African National Standard. Drinking Water. Pretoria: South African Bureau of Standards. 19. Siebel, E., Wang Y., Egli, T. & Hammes, F. (2008). Correlations between total cell concentration, total adenosine tri-phosphate concentration and heterotrophic plate counts during microbial monitoring of drinking water, Drink-ing Water Engineering and Science, 1, pp. 1-6. 20. WHO (2011). Guidelines for drinking-water quality: WHO Library Cataloguing-in-Publication Data. 4th ed. Ge-neva: World Health Organization, available at: htttp://www.unep.org/greeneconomy. Water in the Transition to a Green Economy. 

Microbiological water quality along Vaal Gamagara’s potable water distribution system

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Microbiological water quality along Vaal Gamagara’s potable water distribution system

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