ABSTRACT
Leachate flow from urban dumpsites into surface and ground water sources can be detrimental to the urban population who use these waters sources. Gradual accumulations of contaminants in the water sources can result into high loads of pollutants which are potentially toxic to the users. In Ikirun Asa river that drain through the town and improved ground water wells are the main sources of portable water for most residents. The major aim of the study was to determine the impact of municipal solid waste disposal on Ground water contamination of these urban water sources. Specific objectives were to establish levels of pollutants in the wells and stream as compared to guidelines provided by NBS for drinking water and NEMA standards for effluent discharge to portable water sources; to determine the effects of wet and dry seasons on wells and stream water pollution and to determine the correlation between levels of pollutants in the water sources with respect to the distance from the dumping site. Four wells were purposively sampled for the study during the dry and wet seasons (August, September and early October, 2020). Surface water samples were collected from the stream at depth of ≤ 30m at sampling points located 400m and 800m upstream and downstream. Water samples from the wells were directly collected from the improved Well taps. All samples were analyzed for physiochemical and biological pollution indicators. The physicochemical parameters investigated included: Temperature, pH, Electrical conductivity and anions No3- which were determined used using the standard analytical methods. Trace metals Pb, Cd, Zn and Mn were determined using Flame Atomic Absorption Spectrophotometer. Bacteriological analysis was done as prescribed by the standard methods for analysis of water and wastewater. The data obtained was analyzed using SPSS software. The levels of electrical conductivity (EC), Manganese (Mn), Zinc (Zn), Lead (Pb), Cadmium (Cd), NO3- and E.coli in the leachate and portable water are higher than NBS/NEMA standards indicating possible health impacts posed by the dumpsite on surface and ground water quality. In all standards the total coli forms were found to be higher than 1600 counts/100ml posing a pathogenic health effect. The surface and ground water have pH within NBS acceptable range for drinking water. The seasonal effect was manifested by increased pollutants levels during the wet seasons as compared to dry seasons that were attributed to the solubility of organic material and increased runoff to the stream and percolation during the wet season as compared to the dry period. The concentration of pollutants had negative correlation with distances from the dumpsite. Pollutants concentration levels downstream are least related between streams and well. Thus water flowing downstream had negative correlation both in Zn (r= -.677, P= .323) and Mn (r= -.655, P= .345). This could have been due to other factors like the industrial activity at the lower part of the dumpsite. The results depict need for periodic assessment of the water quality and enactment of law on the safe distances for establishing Wells from the dumpsite areas.
CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Development in the 20th century has changed rural communities to cities and towns to face a lot of environmental challenges. Such environmental issues are being addressed at global, regional and local levels (Smith, 2010). One of the most current environmental issues is on solid waste management from domestic, commercial and industrial sources. Solid waste management problem was identified during the United Nation Conference on Environment and Development (UNCED) in Rio de Jenairo in 1992 and today emphasis is on reducing wastes. Also identified was the need to maximize reuse and recycling of Indiscriminate disposal of Solid waste (UNEP, 2010).
Solid waste management is one issue facing authorities in the fast-growing cities especially in developing countries. In Africa solid waste disposal is given priority over water quality according to the World Health Organization (Zerbock, 2003). In urban Africa explosive population growth rates is seen to translate into generation of noxious toxic chemicals (UNEP, 2010). Regardless of this kind of situation in Africa there is lack of infrastructural endowments to face challenges associated with huge amounts of Indiscriminate disposal of Solid waste (Ogwueleka, 2009) and as a result, heaps of Indiscriminate disposal of Solid wastes are common in the urban centres.
In Nigeria the most common waste disposal method available is open dumping, incineration, composting and land filling. Selection of open dumping is based on geographical rather than geological and hydrogeological considerations (Widmann, 2006). Open solid waste dumping is common practice since it is quite economical for municipal solid waste (Ustohalova et al, 2006). Being economical most dump sites accept a variety of semi-solids, non-hazardous solids, and liquid wastes from diverse sources, such as industrial, households, businesses, agricultural, medical facilities, restaurants, and schools. Contaminants from gasoline spills, households and other toxic wastes find their way to the dumping sites (Calvo, 2005). Available literature in Nigeria show that such indiscriminant dumping threatens both human health. Repercussions range from water pollution, flooding, ugly sights of stinking and pest-infested piles of Indiscriminate disposal of Solid waste and spread of diseases in urban areas (Gakungu et al, 2012).
1.2 Statement of the Problem
Ikirun has an urban population of 69,740 based on the 2009 National Population and Housing Census and a day population of 400,000 people (MCK, 2011). This high population is increasingly putting a lot of pressure on the existing infrastructure. The rivers that were once the major sources of water for domestic use are polluted resulting to people using wells as the alternative source of water. The dumpsite located close to the streams and ground water recharge areas easily release pollutants to this water bodies. With gradual accumulation pollutants can become harmful to the end users. The research determined the concentrations of pollutants with regard to guidelines as determined by Nigeria Bureau of Standards (NBS, 2006) and NEMA effluent levels for waste water discharge, seasons and distance from the dumpsite.
Leachate from municipal dumping sites is a potentially polluting liquid to ground and surface water if not well managed. Low level discharges of contaminants may not be harmful but long-term partitioning to the sediments can result into high toxic accumulations that may have serious effects on the users. In Ikirun Asa river that drains through the town and ground water wells are the main sources of portable water for most residents. Ilorin municipal dumpsite located along the river is the single solid waste dumping site in Ikirun. Leachate from the dumpsite finds its ways through surface runoff to Asa river while also percolating to the ground water aquifers. Since most of the urban residents in Ikirun predominantly use these water sources it is necessary to determine the concentration levels of the pollutants in these water sources so as to ascertain their suitability for domestic use. Therefore, the aim of the study was to determine the impacts of Indiscriminate disposal of Ground water contamination.
1.3 Research Questions
The research questions for the study were:
i) How are the levels of pollutants in the wells and stream water compared to guidelines provided by Nigeria Bureau of Standards for drinking water and NEMA effluent discharge levels?
ii) What are the effects of wet and dry seasons on pollutant levels in stream and well water?
iii) How do levels of pollutants in wells and surface water vary with distances from the sampling sites?
1.4 Objectives of the Study
1.4.1 General Objective
The main objective was to determine the effects of Ground water contamination in Ikirun, Nigeria.
1.4.2 Specific Objectives
Specific research objectives were to establish;
i) The levels of pollutants in the wells and stream water as compared to guidelines provided by Nigeria Bureau of Standards for drinking water and NEMA effluent discharge guidelines.
ii) The effects of seasons on wells and stream water pollutants levels
iii) The correlation between levels of pollutants in wells and surface water with distances from the dumping site.
1.5 Hypotheses
i) There is no significant difference in levels of pollutants in ground water and surface water from the guidelines set by Nigeria Bureau of Standards (NBS, 2006) and NEMA, 2012.
ii) Seasons have no significant effect on ground water and surface water quality
iii) There is no significant correlation between levels of pollutants with distances from the dumpsite.
1.6 Significance of the Study
The information obtained will help the Ikirun government in policy formulation on waste management and location of wells as well as monitoring of the pollution levels of the stream and wells. This study yielded data and information that will be useful in managing the level of pollutants in the wells and stream based on the guidelines provided by NBS and NEMA effluent discharge recommended minimum levels. The findings of this study will help the Urban government in decision making and institutionalization of a framework for waste management.
1.7 Scope and Limitation of the Study
1.7.1 Scope of the Study
This study was carried in Ikirun, in Ilorin, Kwara state. The study focused on the effects of the Ilorin Municipal dumpsite leachate on Ground water contamination. Physico-chemical and biological parameters of water and leachate were determined. Sampling was based on the leachate discharge from the dumping site, wells and the surface water in Ikirun. Water samples were collected during the wet and dry seasons.
1.7.2 Limitations of the Study
The study determined the effects of dumpsite leachate on the groundwater and surface water during the two seasons. The parameters measured were limited by financial constraints and time hence the results are limited in revealing the trends over time.
1.8 Conceptual framework The conceptual framework is based on the relationship between leachate generation and the quality of the surface water and the ground water. The solid waste management elements are the basis of waste management practices of achieving environmental health. The management of Indiscriminate disposal of Solid wastes at the dumping sites with time, solid waste characteristics and other intervening factors were significant in correlation to the quality of the surface and ground water.
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