CHAPTER ONE
INTRODUCTION
1.1 Background
In many developing countries like Nigeria, the problem of environmental management is severe because of lack of strong legislation and institutional capacity for integrated planning and management especially of wastewater. It is estimated that approximately two-thirds of the population in the developing world has no hygienic means of disposing excreta and even greater number of them lack adequate means of disposing of wastewater (Mara et al., 2010). The frequent outbreaks of diseases such as diarrhea, cholera, and typhoid in developing countries have been partly attributed to these depressing factors. Also haphazard disposal of untreated wastewater from households, institutions and industries has caused severe deterioration of water bodies in many developing countries.
The World Health Organization (2006) has predicted that as freshwater becomes increasingly scarce due to population growth, urbanization and, probably, climate change, the use of wastewater, excreta and greywater in agriculture and aquaculture in developing countries would become increasingly attractive. Unfortunately, in developing countries including Nigeria, emphasis is on improving drinking water quality rather than the safe and sustainable wastewater treatment and re-use. This is because as at now, the quantity of available potable water to an individual is still far below recommended levels.
Experience has shown that the conventional centralized wastewater management systems which have proved to be effective in developed countries seem to have serious operational challenges in many developing countries including Nigeria, due to the high costs of
construction and operation, maintenance of facilities, power, and lack of experienced and skilled manpower.
In recognition of this, coupled with the desire to have an efficient and cost-effective wastewater treatment system, the Ahmadu Bello University, Zaria employed waste stabilization ponds (WSPs) for its wastewater treatment. The effluents from the waste stabilization ponds are used by farmers living around the institution for irrigation. The wastewater generation in Ahmadu Bello University, Zaria cannot be devoid of any trace of heavy metals considering the various activities such as medical and science laboratories, electric and auto-mechanic workshops within the university and its environs. Heavy metals are known to be dangerous to life because they tend to accumulate in plants and animals tissues where they cause damage (Ghosh et al., 2012; Shuaibu et al., 2013)
Studies have shown that wetland systems have potentials in controlling water pollution from domestic, industrial and non-point source contaminants (Vymazal, 2005; Rai et al., 2013). Wetland systems use aquatic plants, soils and their associated micro-organisms to remove contaminants from wastewater (Sohair, et al., 2013; Rai et al., 2015). They are simple, effective, reliable and economical technology compared to several other conventional systems. Wetlands are transitional areas between land and water. The term “wetlands” encompasses a broad range of wet environments, including marshes, bogs, swamps, wet meadows, tidal wetlands, floodplains, and ribbon (riparian) wetlands along stream channels ( UN-HABITAT, 2008).
There are various types of constructed wetland systems for treating wastewater based on the type of plants used, type of media used and flow dynamics. A constructed wetland (CW) is a biological wastewater treatment technology designed to duplicate processes
found in natural wetland ecosystems. Constructed wetland systems are either surface flow or subsurface flow wetlands that use processes such as biological, chemical, physical and microbial means for the treatment of wastewater. The surface flow wetlands are constructed to resemble natural wetlands while the subsurface flow wetland is a bed of porous media, such as sand or gravel, usually vegetated and which can either be vertical flow or horizontal flow by configuration.
1.2 Statement of Research Problem
Industrialization and urbanization in developing countries like Nigeria have brought about pollution of water bodies in urban cities with inherent consequences including compromised sanitation, public health, poor nutrient recovery in the ecosystems and pollution of freshwater resources. Unfortunately, the developing countries lack the required power and water supply, capital layout and experienced and skilled manpower to operate and maintain conventional wastewater treatment plants. This has been the major contributor to poor wastewater treatment and disposal in developing countries.
The presence of heavy metals in aquatic environments has been a matter of concern
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