ABSTRACT
There is an increase in exposure of water sources to faecal contamination as a result of expanding anthrogenic activities in Lake Naivasha basin in Kenya. This contamination exposes water users in the region to a variety of health risks. This study investigated faecal pollution of community water sources (lake, rivers and boreholes) within Lake Naivasha basin through determination of the concentrations of total coliforms, Escherichia coli, intestinal enterococci, Clostridium perfringens and heterotrophic bacteria in various water sources using Membrane Filtration Technique (MFT) and Heterotrophic Plate Count (HPC) procedures. The potential of solar pasteurization in disinfecting domestic water was also explored by heating known volumes of water samples in a black solar box cooker at given time intervals. In addition, determination of E. coli to intestinal enterococci ratio was used in faecal pollution source tracking. Physico- chemical parameters were measured in situ for all water sources. Data was analysed for mean variation using Statistical Package for Social Sciences (SPSS) version 17 software. Surface water sources gave higher values for all microbiological parameters than borehole sources. Borehole direct sources showed no significant variation for all microbial parameters (E. coli, total coliform, intestinal enterococci, C. perfringens and HPC) with respect to sampling sites, the same was also observed in borehole at the Points of Access (POA). Surface water sources on the other hand, showed significant spatial variation for all microbial parameters (P<0.05). Samples from borehole POA, households in Karagita, Mirera and Kamere villages and vendors showed no significant variation for all the microbial parameters. The use of solar radiation in water disinfection showed that temperature of 75 0C attained after 30 minutes from pasteurization point completely eliminated E. coli and total coliforms from all the water sources. E. coli to intestinal enterococci density ratios from all the water sources were closer to 0.7; showing that non-human warm blooded animals were the most possible sources of faecal pollution into these water sources. In conclusion, there was faecal contamination of domestic water sources in Lake Naivasha basin and poor human handling practices contributed to further deterioration of the water quality. The use of solar radiation can be recommended as a cost-effective method of disinfecting water for domestic consumption to reduce likely incidences of waterborne diseases. Use of other methods such as ribotyping is also recommended in tracking the possible sources of faecal pollution into water sources in Lake Naivasha Basin.
CHAPTER ONE
INTRODUCTION
Background information
Naivasha is one of the fastest growing towns in Kenya. Its growth is enhanced by the increasing horticulture farming and associated businesses, especially floriculture around the lake Naivasha (JICA, 2003). In addition, the area surrounding the lake offers a mild climate and natural beauty that has attracted tourism. Lake Naivasha also supports a productive fishery that provides jobs and income as well as being an important source of fish protein for local communities. Tourism activities in the region have contributed to growth in population in Naivasha District. In addition, rural to urban migration as a result of falling farm incomes from traditional cash crops, and commercial enterprises and good prospects for job opportunities have also led to tremendous rise in population density in this District. This has risen from 43,867 persons in 1969 to 376,246 persons in 2009 (Government of Kenya Census Report, 2009). Horticultural activities employ around 30,000 people in the region and it is one of the nation’s largest foreign exchange earner (Japan International Co-operation Agency (JICA), 2003; Otiang’a and Oswe, 2007).
Provision of water in any country for socio-economic and ecological sustenance is indispensable. Its availability is primarily influenced by its quantitative distribution in time and space, and by its quality. As is common with other areas in developing countries, direct surface water is still the most important source of domestic water (World Health Organization (WHO), 2002). In the case of Naivasha area, River Malewa provides water for approximately 250,000 people within the townships surrounding the lake (M’Cleen, 2001; LakeNet, 2003). Other sources of water include bore holes, rain water harvesting, shallow wells and lake water. Despite these being the main sources of water for the communities in this area, they are under threat of pollution from anthropogenic activities in the heavily populated area and from the Lake Naivasha catchment (Harper and Mavuti, 2004).
Faecal contamination from human and other animals in this area is recognized as the major water pollutant and it has a bearing on public health (M’Cleen, 2001). Lack of adequate access to sanitation, safe and clean drinking water imposes significant economic losses on the population.
The WHO has estimated that 80% of all sicknesses and diseases in the world are caused by inadequate sanitation, faecal pollution and unavailability of water. About 1.7 million annual human deaths are attributed to contaminated water supplies. Most of these deaths are due to diarrhoeal diseases which also affect 90% of children from developing countries mainly due to bacterial pathogens contamination (WHO, 2002). There is likelihood of contamination of both surface and groundwater sources within Naivasha due to inadequate sanitation as communities here depend on bushes, pit latrines and septic tanks for sewage disposal (Mireri, 2005).
In places where water is inadequate or where its quality standards does not make it available for other uses, people have conflict and fight over water. Critical to our modern civilization is the availability of a clean water supply for drinking and bathing. Unfortunately, many pathogens get transmitted through its supply. Some of these pathogens enter water from faeces of ill individuals or of healthy disease carriers, are ingested and transmitted to other people. Waterborne diseases (WBD’s) such as polio, typhoid, cholera, hepatitis, shigellosis, salmonellosis and others spread in this manner and the spread may be very high in densely populated areas such as Lake Naivasha area. Other WBD’s such as giardiasis, toxoplasmosis and cryptosporidiosis (all of zoonotic origin) are also becoming common as a consequence of unprecedented flooding events emanating from climate change phenomena which has increased pollution in the water sources (WHO, 2002).
Pollution as a result of anthropogenic activities and poor management of water sources have partially or totally turned aquatic environments into dumping sites for waste materials, and as a result, many water sources have been rendered unwholesome and hazardous to man and other living systems (Bakare et al., 2003). There is often conflict on water usage because on one hand, the fundamental fear of food shortages encourages ever greater use of water resources for agriculture while on the other hand there is need to divert water from irrigation food production to other uses and to protect the quality of the resource. Many people believe this conflict is the most critical problem to be tackled in the 21st century and it was a key topic for discussion of the Framework for Action exercise of the Global Water Partnership (FFA of GWP) (FFA of GWP, 2000).
Regular sampling and analysis provide data on the quality of raw water, the efficiency of water treatment and the integrity of distribution systems. The range of pathogenic micro-organisms is extensive and therefore water is examined for microbiological indicators of contamination. The use of indicator organisms is based on the assumption that if they are present then the pathogen may also be present, and if absent then the water is suitable for consumption or pose a lower risk of transmitting WBD’s (Frahm et al., 2003). To be useful the indicator must be present if pathogen is present and in higher numbers than pathogens. The principal bacteria indicators are the coliforms bacteria; including total coliforms, faecal coliforms and Escherichia coli. Other bacterial indicators include enterococci, Clostridium perfringens and total aerobic bacteria. The key species of the faecal coliform group is E. coli commonly found in the faeces of human and is thus a definitive indicator of faecal contamination (Noble et al., 2003). Therefore, concern about faecal coliforms densities in water sources is of paramount importance within Naivasha region (Mireri, 2005). Ways of finding solutions to the problems of faecal contamination into water sources is essentially necessary. Major solution approaches in this case include tracking of faecal contamination sources and disinfecting water for domestic consumption.
Microbial source tracking (MST) is a technique that can help in solving faecal contamination problems. It is a measurement-based technology which also offers important advantages over source identification practices. This is because by tracking sources of faecal pollution directly, we can better target remediation efforts thereby saving time and resources (Stewart et al., 2003).
Boiling of water and chemical treatment were the common ways of purifying water to make it safe for drinking. However, these methods are expensive, cause environmental damage and require skilled personnel to be applied appropriately (Acher et al., 1997). There has been a major breakthrough in making solar cooking practical through development of a cheap, environmentally friendly and easily available solar box cooker for use in the tropics (http:www.solarcooker.org). Since then, the use of solar radiation as disinfection method has become a common method in purifying water for domestic consumption in developed countries (Lawand et al., 1997). In developing countries, the major source of energy for cooking and boiling water is firewood which is expensive and environmentally unfriendly. Solar energy is non-degradable resource which has been put to little use for the benefit of mankind in developing countries and hence need to be explored in the tropics for the improvement of human health (Sinton et al., 2002). This study determined the densities of faecal contamination indicators in various community water sources within Lake Naivasha basin. The effects of human handling on the quality of water as well as the potential of solar radiation disinfection in water quality improvement were also explored.
Statement of the problem Consumption of untreated water can result in waterborne disease outbreaks and transmission. The problem is common in densely populated areas like Lake Naivasha basin where sewage disposal problems and poor water handling practices at sources, public and domestic domains compromise domestic water quality. This also increases chances of contracting and transmitting Waterborne diseases (WBDs) (Plate 1). For this reason analysis of bacteriological quality of water sources at vendors and household domains within Lake Naivasha basin is necessary. This will help in revealing the quality status of water for domestic use and to come up with appropriate remedial measures. The easiest and quickest way of determining the safety level of water sources is by testing for the presence of faecal pollution indicators. In addition, exploring the use of solar radiation in domestic water disinfection is needed to improve the quality of water for domestic consumption. This is particularly useful to a community where the use of other methods of purifying water is not easily affordable. This study therefore determined the bacterial quality of water used by communities within Lake Naivasha basin and explored the use of solar radiation disinfection of domestic water.
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Item Type: Kenyan Topic | Size: 68 pages | Chapters: 1-5
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