The study investigated the effects of industrial effluents discharges on stream water quality in Onitsha urban area of Anambra State. Effluents quality assessment was carried out on samples collected at eight (8) locations of the sampled industries while water quality assessment was carried out first on three (3) samples collected upstream or at control sites as well as on eight (8) samples collected at discharge locations in Onitsha urban area in 2015. The control sites were located upstream 500 meters before contact with discharge effluents. The physico-chemical and microbiological parameters analyzed were Temperature (T), pH (Hydrogen ion concentration), Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Turbidity, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Magnesium (Mg), Nitrate (NO3), Iron (Fe), Calcium (Ca), Zinc (Zn), Sodium (Na), Copper (Cu), Lead (Pb), Chromium (Cr), Total Heterotrophic Counts (THC) and Total Coliform Group (TCG). The results of the analyses revealed significant concentration of many dissolved salts, heavy metals and pathogenic organisms in the water samples due to effluents intrusion. Discharged effluents deviate radically from the WHO(2011) standards: Temperature ranged from 290C to 360C, TDS ranged from 0.7mg/l to 6.10mg/l, DO ranged from 35mg/l to 143.6mg/l, Turbidity ranged from 100ntu to 400ntu, BOD ranged from 2.06mg/l to 41.9mg/l, COD ranged from 2.08mg/l to 53.9mg/l, Mg ranged from 0.12mg/l to 3.09mg/. These values were above WHO (2011) standard limits for drinking water while others like pH which ranged from 5.5 to 12.0, Ca which ranged from 0.60mg/l to 8.24mg/l, Zn ranged from 0.01mg/l to 0.70mg/l, Na ranged from 0.14mg/l to 2.69mg/l, and Cu which ranged from 0.02mg/l to 1.68mg/l were below WHO (2011) recommended standards for drinking water. The microbiological parameters like Total Heterotrophic Counts and Total Coliform Groups are highly above WHO standards. The analysis revealed statistical significant differences between the water samples at control and the water samples at discharge locations. MANOVA was used as a test instrument in this study because it allows for maximum interactions between all the variables. Taken together the findings show that there are contaminations of the streams investigated by industrial effluents and that the stream waters are not safe for drinking purposes. Appropriate management measures were suggested to minimize effluents contamination of surface water in the study area.
- BACKGROUND TO THE STUDY
Governments and organizations all over the world recommend industrialization as the quickest track to economic development (UNDP, 2010). The major advantages of industrialization as a short and quick path to economic development are the massive production of goods and services, short gestation of investments, high net worth yield of capital and near total economic independence (Uchegbu, 2002). In addition, employments are created by direct linkage and trickle down effects in the national economies (Ajayi, 2007). Industrialized countries generate more funds directly from their manufacturing industries which they use to procure other items needed in their countries. These advantages commend industrialization to all the countries of the world as a quick means to economic development (Uchegbu, 2002). Based on this, various countries create laws and policies that favour and promote industrialization (Bichi and Anyata, 1999).
But industrialization, though beneficial, has quite a lot of environmental problems that result from the manner of the production streams in the various industries, as each type of production process and the nature of the inputs in the production process, yield diverse types of industrial wastes (Uchegbu, 2002). Industrial wastes and effluents refer to the wastes that are generated from industries as a result of the production processes of the industries (Uchegbu, 2002). Industrial wastes and emissions contain toxic and hazardous substances most of which are detrimental to human and animal health (FEPA, 1991). Some of these substances are lead, cadmium and mercury (heavy metals), and toxic organic chemicals such as pesticides, polychlorinated biphenyls (PCBs), dioxins, polyaromatic hydrocarbons and phenotic compounds. The Federal Environmental Protection Agency (FEPA) in 1990 identified industrial waste as a major environmental problem requiring urgent attention in Nigeria and noted that many chemical industries in the coastal areas contribute to increases in the amount of chemical effluent load pollution in the Nigerian coastal waters.
Industrial wastes exist in three forms; – solid wastes, liquid and gaseous effluents (Uchegbu, 2002). Liquid industrial effluents are liquid wastes which are produced in the course of industrial production activities (Echiegu and Liberty, 2013). These wastes are residues of either uniform or diverse composition which have been found to be of various degrees of toxicity (Echiagu and Liberty, 2013). There are, in many countries, policies and laws which guide and control the production and management of industrial wastes because of their hazardous nature (Uchegbu, 2002; Ubachukwu, 2012).
Nigeria has laws and policies on industrial waste production, control and disposal (Uchegbu, 2002). The laws are the Federal Hazardous Waste Management Regulation of 1991; The Environmental Impact Assessment (EIA) Act of 2004; The Harmful Waste Act of 2004; The National Environmental Standards and Regulation Enforcement Agency (NESREA) Acts of 2007 etc. According to Mozie (2011), the problem in Nigeria is not the absence of regulatory laws but the low obedience to and the poor or the near non-enforceability of the many environmental laws of the country. The non-enforcement of the environmental laws over the years, has led to the improper disposal of industrial effluents and this has now become a major problem and a source of concern to both governments and industrialists in Nigeria (Mozie, 2011).
In many developing countries, such as Brazil and India, the disposal or discharges of effluents, (even when these are technologically and economically achievable for particular standards) do not always comply with pre-treatment requirements (Echiegu and Liberty, 2013). When this happens, the human society pays a great price for improper disposal of industrial wastes. In Amazon, Brazil for instance, Di-Mario (2004) reports that prospecting for gold has resulted in rivers and fish being severely contaminated with mercury used in the refining process in the country while Charles and Margaret, (1993) and Mason, (1998) also describe the effects of acetaldehyde and chloride discharged from a factory into Mina-Mata Bay in Japan in 1950s which killed many animals such as dogs, cats and pigs involved in the consumption of water extracted from Mina-Mata Bay in Japan. In 1958, when the number of victims exceeded 50 people, 21 of whom died, a ban was placed on the sale of fish from Mina-Mata Bay, though there was no restriction on disposal of industrial effluent on surface waters. The effects of industrial effluents on surface water can remain a threat for long period of time because of bioaccumulation of toxins in animal or human tissues.
There is at present general lack of information on the effects of effluents discharged by these industries on the water quality of the streams crossing the urban areas in Nigeria. The choice of Onitsha for this study is based on the fact that many effluents producing industries are located in the urban area. Onitsha urban area is slopy which means that runoff water can easily drain the effluents and discharged them into nearby streams. The drainage pattern and topography make the available streams in the urban area vulnerable to pollution from industrial activities particularly by effluent discharges. Still, the urban residents depend on the urban streams for domestic and related purposes. See plates 1, 2 and 3.
Therefore, to effectively and properly protect the available streams and their uses in the study area, it is crucial to assess the effects of effluents discharge chemistry and translate the information (which is currently lacking) into reliable and sustainable management strategy that will guide urban planners, policy makers, stream end users and water resources providers to prevent or minimize harmful impacts of stream water contamination and ensure sustainability of fresh water resource availability for urban users and the ecosystems. Based on these therefore, this work seeks to characterize the liquid effluents discharged by industries in Onitsha urban area and establish their deleterious effects on the water quality of streams in the study area. Uchegbu (2002) reports high incidence of diseases and deaths in the study area and noted that the causes of such deaths may not be unconnected with the use of contaminated surface waters in the area for domestic and other purposes.