CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Human activities on earth give rise to residual materials which are not of immediate use where they arise. These residual materials may be recycled, reclaimed, or reused; otherwise they constitute waste which will ultimately be released to the environment in mobile form or insitu (USEPA, 2008). The biosphere has the capacity to transform many wastes over time, either into harmless products or into nutrients which can be used again. However, the natural assimilative capacity of the environment can easily be exceeded if waste particularly from man’s activities is not controlled.
Waste is generated universally and is a direct consequence of all human activities. The disposal of solid waste into the land has been recognized as the major source of groundwater contamination. Waste disposal by land fill has led to pollution of groundwater resources under a wide range of conditions around the globe (Afzal and Elahe, 2008).
Waste is defined as unwanted or undesired materials accumulating after the completion of a process (Cointreau, 2001). Waste was also characterized as items that are no longer used for any significant function. They are classified as items with hazardous properties. Such hazardous wastes include household dump items, sewage, sludge, waste from manufacturing industries etc. (Obeka, 2005). The United Nations Environmental Programme (UNEP Yearbook, 2006) defines waste as those materials which the initial user has no further use for either purposes of production, transformation or consumption and of which can be disposed off.
Wastes generally exist as solid, liquid and gas. Liquid waste are wastes that are free flowing such as fluids, waste water, fats, oil, or grease. They are usually generated from industrial activities like refineries, textile industries, waste water treatment plants etc. These wastes are usually emitted and disposed off on land thereby causing land pollution and also at times in water bodies causing water pollution.
Gaseous waste on the other hand comprises gases and small particles emitted from open fires, incinerators, and vehicles, or produced by agricultural and industrial processes. Once released, the effects of these gases and particles are hard to control. These wastes include gases like carbon dioxide, carbon monoxide, sulphur,
chlorofluorocarbon etc.
Solid waste is defined as nuisance, unwanted or discarded material with insufficient liquid content or gas for free movement (Vision 20:20). Cointreau (1982) defined solid waste as non-air and sewage emission created within and disposed off by a municipality, including household garbage, commercial refuse, construction and demolition debris, dead animals and abandoned vehicles. Solid waste is a major health hazard in most urban areas in Nigeria.
Adebibu (1985) grouped solid wastes into eight classes, namely domestic,
municipal, industrial, agricultural, pesticides, residential and hazardous wastes. However, solid waste can be classified as biodegradable, or non-biodegradable, soluble or insoluble, organic or inorganic, toxic or non-toxic (Kostawa, 2006; Ajadike, 2007). Irrespective of the classification of solid wastes, most of the urban wastes are degradable which aid the rate of leachate formation and migration compared to non-biodegradable that can last for many years without any sign of decomposition. There is therefore a possibility of leacheate generation, plume extension and migration at the base of urban land fill owing to the decomposition of discarded materials and frequent surface water ingression from urban precipitation. According to Irina (2006), concentration (mg/L) of leacheate constituent are in phases namely; transition (0-5 years), acid formation (10-20 years) and finally maturity (>20 years). Groundwater may not be contaminated at the inception of waste deposition in the landfill. The age of the landfill significantly affects the quality of leachate formed.
The ageing of a landfill is accompanied by increased quantity of leachate. Leachate generated at the initial period of waste deposition (up to five years) in refuse dumpsite has a pH value range of 3.5-6.5 indicating the presence of carboxylic acids and bicarbonate ions. With time, pH of leachate becomes neutral or weakly alkaline ranging between 7.0 and 7.6. Landfills exploited for long period of time gives rise to alkaline leacheate with pH range of 8.0 to 8.55 (Slomczynska and Slomczynski, 2004; Longe and Balogun, 2010). Waste placed in landfills or open dumpsites are subjected to either underflow or infiltration from precipitation. Areas near landfills have great possibility of groundwater contamination because of potential pollution source of leachate originating from the natural environment. Naturally depth from surface, soil type, bed rock, geology, permeability of sediments and climatic variation affect groundwater quality.
Solid waste disposal or dumping creates environmental problems in two main ways. First, much of it is not disposed off and collected on time. In essence the rate of waste dumping is faster than the rate at which it is disposed or cleared. Much of it is burnt or dumped along the streets or haphazardly in illegal land fills. This creates health hazards, blocking drainages, initiate flooding and contamination of ground water quality.
Secondly, because of the inability to sort waste at source, household waste and industrial wastes including toxic waste are often handled together leading to soil and underground water pollution (Osibanjo, 2008).
Water is a common chemical substance that is essential for the survival of all known life forms. Water normally exists in three forms which are Solid, Liquid and Gas (Robert, 1969). Next to air, water is the most essential element for all form of biological activities, comprising over 70% of the earth surface (Longe and Enekwechi, 2007). Annan (2003) described potable water as precious, we cannot live with out it, and human activities have a profound impact on the quality and quantity of water available. Water is of great importance for domestic industrial, agricultural, religious and recreational uses. Water is classified under two main categories based on its location and these are surface and groundwater (Appelo and Posma, 2005).
Groundwater refers to any subsurface water that occurs beneath the water table in soil and other geologic forms (Rail, 2000). Scientists estimate that groundwater makes up to 95% of all fresh water available for drinking. Groundwater is a significant source of water for many municipal water systems, and residents withdrawing their waters from wells, also rely upon groundwater. Surface water refers to water occurring in lakes, rivers, streams ponds and sea and they are found over the surface of the earth. Surface water occupies a vast part of the earth surface (about 70%). Surface water is naturally replenished by precipitation and naturally lost through discharge to evaporation and sub surface seepage.
Contrary to the widely held theoretical view of groundwater being the “safest” water for consumption, some wells are found to be polluted in terms of temperature, mineral contents, particles solute, organic matter and bacterial concentration (Appelo, 2005). These contaminations are mainly gotten from municipal land fill leachate which are highly concentrated complex effluents that contain dissolved organic matters; inorganic compounds such as ammonium, calcium, magnesium sodium, potassium, iron, sulphates, chlorides, copper, lead, nickel, zinc and xenobiotic organic substances (Lee and Jones-Lee, 1993; Christensen, 2001; Tengrui, Al-Harbawi, Lin, Jun and Long, 2007; Ogundiran and Afolabi, 2008).
Therefore, supply of adequate fresh water in large quantity to meet man’s demand and maintaining the quality is now a thing of concern (Elinge, Itodo, Birn, Yauri and Mobongo, 2011). Hence contamination of groundwater through the infiltration of leachates via the soil and rocks need to be avoided. The contamination normally takes many years and takes place within a particular distance from the dumpsite. It is very important to avoid the contamination since pipe borne water is not readily available in many parts of Nigeria both in urban and rural areas (Adelekan, 2010). With this problem, there is need for alternative source of water supplies which is groundwater, but due to lack of proper waste management the groundwater is usually affected by refuse dumpsite (Mohammed, 2011). Water is said to be polluted when the water body is adversely affected by organic and inorganic contaminants (Oliver and Ismaila, 2011).
1.2 STATEMENT OF THE RESEARCH PROBLEM
Inadequate solid waste management is a major environmental problem in Nigeria in general and in Samaru-Zaria in particular. The contributing factors range from technical problems, to financial and institutional constraints. There is an absence of any properly designed solid waste disposal facility in Zaria, therefore posing contamination risk to both ground and surface water. The pollutant species in the dumpsites will continue to migrate and attenuate through the soil strata and after certain period of time might contaminate the groundwater system if there is no action taken to prevent the phenomenon (Gandhimath and Kanami, 2013). Groundwater is known as the major source of water supply in Samaru, Zaria and its contamination is a major environmental and health concern.
Past studies have shown impairments of groundwater quality through leachates outflow and infiltration from solid waste dumpsites. These include Akinbile and Mohammed (2011), who worked on environmental impact of leachate pollution on groundwater supplies in Akure, Nigeria. From their result, out of three samples collected from boreholes located near a landfill at Akure, only one of the boreholes was strongly polluted and requires treatment before use. Mohammed (2011), in his research on effects of refuse dumps on groundwater quality in Minna, Niger State, water samples were obtained during dry and wet seasons from hand dug wells. The wells were selected close to the dumpsite. pH and conductivity were determined using standard methods. He discovered that all the samples were not in conformity with World Health Organization
(WHO) limit for bacteriological values which make the water to be unsafe for drinking, he then concluded that hand dug well water around the refuse dump sites are not safe for human consumption.
Afolayan, Ogundele and Odewumi, (2012) also conducted a study on
hydrological implication of solid waste disposal on groundwater quality in urbanized area of Lagos State, Nigeria. From their study of empirical and experimental examination of the concentration of contaminants in groundwater of fifteen (15) wells, the results they got were analyzed with standard statistical package and compared with World Health Organization (WHO), 2004 and Nigeria Standard for Drinking Water Quality (NSDWQ), 2007 standard limit. They discovered that pH, chloride, iron, and lead are higher around the operational landfills than the non-existing landfill. It was concluded that groundwater contamination is the function of types of waste, season, topography, soil, underlying geology, surface water ingression and direction of groundwater flow.
Yaya and Okafor (2010) also analyzed the microbial status of groundwater and surface water in the federal capital city of Nigeria (Abuja) taking samples during the dry season and rainy season. Result of the research revealed that coliform count in most of the water samples from borehole satisfy the permissible level prescribed for drinking water in the two seasons in line with the WHO and NSDWQ. This was not so for samples from rivers and streams in the same area.
Bello (2011) conducted a similar research on effects of dumpsites on groundwater quality in Samaru-Zaria, Kaduna State. A result of the research study revealed that groundwater in Samaru is not totally pure. He then went further to conclude that the groundwater of the study area especially from wells, is not good enough for direct consumption following evidence of high coliform count in most wells in Samaru.
All the studies conducted on groundwater quality from the review done where conducted outside Zaria, except that of Bello (2011), which was conducted in Samaru- Zaria, Kadauna State. Though the research of Bello (2011) was conducted in SamaruZaria, same study area as the present research work at hand, there are some gaps in
Bello’s work that this present research seeks to address.
The research conducted by Bello (2011), was conducted to only assess the biopysico- chemical properties of shallow and deep well water in the study area, while the present research assessed both the physico-chemical properties and also level of heavy metal concentration in both shallow and deep well water in the study area. The work of Bello (2011) was conducted using two dumpsites, while the three major dumpsites in Samaru were used for the present study. Finally in the study carried out by Bello (2011), the dumpsite characteristics were not conducted, but the present study carried out a test for heavy metals in soil samples gotten from the dumpsites so as to relate it with the results gotten from groundwater samples in the study area. Finally in the present research the analysis for physico-chemical characteristics and heavy metals was conducted both during the dry and wet season, but that of Bello (2011) was conducted during the rainy season.
Such a study therefore, to the best knowledge of the researcher has not been
carried out. It is as a result of this that the present study aimed at assessing the effects of solid waste dumpsite on groundwater quality of Samaru-Zaria, Kaduna State. The specific research questions the study seeks to address are:
i. What is the proximity of the dumpsites to and from wells in the study area?
ii. What are the physico-chemical characteristics of water in shallow and deep wells of the study area?
iii. What is the level of heavy metal concentration from soils at the dumpsites in the
study area?
v. What are the levels of heavy metal concentration of water in well from well of the study area?
1.3 AIM AND OBJECTIVES OF THE STUDY
The aim of this study is to access the effect of leachate from solid waste dumpsites on groundwater quality in Samaru, Zaria, Kaduna state, Nigeria. This aim was achieved through the following objectives which are to:
i. identify the proximity of dumpsites to and from wells in the study area.
ii. determine the physico-chemical characteristics (Biological Oxygen Demand
(BOD), Total Dissolved Solid (TDS), Dissolved Oxygen (DO), Chemical Oxygen Demand (COD), chloride (Cl), total hardness, colour and pH) of water in wells of the study area.
iii. assess the level of heavy metal (magnesium, zinc, iron, chromium, and lead) concentration from the soils at the dumpsites in the study area.
v. assess the levels of heavy metal concentration in water from wells in the study area.