Physico-chemical Investigation On Dumpsite Leachate
[A CASE STUDY OF ILORIN METROPOLIS]

CHAPTER ONE
1.0    INTRODUCTION
1.1    Background of the study
The municipal solid waste dumpsite (MSWD) examined is located at sawmill, okefomo and irewolede at yidi road street and within Ilorin Metropolis Kwara State. The dumpsites examined contain both biodegradable and non-biodegradable materials of all sorts. The different waste materials may contain different physical, chemical and biochemical properties. In the presence of atmospheric water, high temperature and high microbial populations, these waste materials may decompose and get dissolved in the presence of water to generate a waste liquid substance called leachate. This waste water produced may infiltrate into the ground water aquifer, it may be washed into a nearby surface stream and it may affect soil properties. When humans come into direct contact with such contaminated samples, it may lead to public health problems.
           The gradual increasing population and the proliferation of basic industrial processes particularly in major cities of the world has led to civilization that have greater impact on the environment. The disposal of domestic, commercial and industrial garbage in the world is a problem that continues to grow with human civilisation and no method so far is completely safe. Experience has shown that all forms of waste disposal have negative consequences on the environment, public health, and local economies.
Dumpsites are often established in disused quarries, mining or excavated pits away from residential areas. Designated government agency, corporate bodies and some individuals collect wastes routinely into these dumpsites. Here in Nigeria and particularly in Ilorin, modern landfill facilities are not found in these dumpsites; consequently sorting-out of wastes into degradable, non-degradable and recyclable precious materials cannot be achieved. Poor management of dumpsites could create a number of adverse environmental impacts, including wind-blow litter, attraction of mice and pollutants such as leachate, which can pollute underground soil bed, and / or aquifer. Landfill gas mostly composed of methane and carbon dioxide are produced through biodegradation of such waste. Leachate from dumpsites is of particular interest when it contains potentially toxic heavy metals.
Household and industrial garbage may contain toxic materials such as lead, cadmium, mercury, manganese from batteries, insect sprays, nail, polish, cleaners, plastics polyethylene or PVC (polyvinyl chloride) made bottles and other assorted products. Inorganic chemical contamination of the environment is due essentially to anthropogenic source, improper disposal and lack of awareness of the health-risk created by such indiscriminate disposal. Lead, cadmium manganese, arsenic and mercury are pollutants which have unknown physiological benefit when ingested (Abdus-Salam & Adekola, 2005; Brady & Weil, 1999).
There is increase awareness of keeping a friendly hygienic environment and Kwara State government has established an out-fit: Kwara State waste management and control agency for proper collection and disposal of wastes generated through domestic, commercial and industrial activities in all cities in the state. This exercise has increased the number of dumpsites without eliminating the local ones. The build-up of heavy metals in soil from anthropogenic sources has been reported to be harmful to crops and human health (Smith et al., 1996). Sources of these metals ranges from industrially and municipally generated (Gibson & Farmer, 1983; Olajire & Ayodele, 1998), automobile emission (Olajire et al., 2002).
Municipal solid wastes were reported to contain large amount of persistent organic pollutants (Minh et al., 2006). The concentrations and transformations of heavy metals in solid municipal wastes lead to accumulation in the food web (Gimmler et al., 2002). The views of many researchers is that the current trend in the municipal wastes disposal and management practices may increase the heavy metal burden of the soil and underground water (Albores et al., 2000, Okoronkwo, 2006, Elaigwu et al., 2007). Most of these metals have no known physiological relevance to the survival of plants and animals.
This research work was undertaken to ascertain the level of soil pollution of major dumpsites in Ilorin metropolis in order to characterise the nature of waste being generated. Some physico-chemical parameters were also investigated so as to determine the relative mobility of toxic metals in the soil and make appropriate recommendations to Federal Environmental Protection Agency (FEPA) and Kwara State Environmental Protection Agency (KWEPA) on the state of soil pollution of the dumpsites in Ilorin.