Modelling the Effect of Industrial Effluents on Water Quality: "A Case Study of River Challawa in Nigeria"

The physicochemical characteristics associated with industrial effluents from the Challawa and Sharada Industrial Estate in Kumbotso Local Government Area of Kano State ad the effect on water quality of a 10.6 km stretch downstream of River Challawa were investigated. The test period covered both wet and dry seasons, with laboratory analysis of field samples and study area. The results obtained indicated that the DO values varied from 0 mg/l to 3.5 mg/l, BOD5 value ranged from 193 mg/l to 1025 mg/l along the river channel. The reaeration coefficient k2 of River Challawa varied from 0.013 to 0.140. The 0.013 to 0.140. The coefficient of correlation between k2 predicted with derived models were 0.229, 0.295, 0.994, 0.842, 0.676, 0.855 and 0.473. An improved technique using the reaeration coefficient values at each section and incorporating the fall velocity gave a profile closer to the measured oxygen deficit values than the conventional approach. The coefficients of correlation for the two approaches are 0.9572 and 0.4558 respectively. The comparison of k2 observed and predicted k2 O'Conner and Dobbins, Ugbebor and Agunwamba, Churchill and Buckingham, and Agunwamba indicated standard errors of 1.5156, 2.3376, 04216, 1.3891, 0.0488, 0.3854 and 1.7721 respectively. Test result also gave a purification factor of 0.40, indicating the stream was polluted and has poor assimilatory capacity. There is need for proper monitoring and impact control measures for River Challawa. I. INTRODUCTION The direct discharge of effluents from industries into rivers and the streams in an arbitrary manner without predetermining the impact of such discharges on animal and plant life is a growing third world environmental problem. Most of the wastewaters are extremely hazardous mixtures containing inorganic and organic components (Fu, et al 1994). The industrial operation consists of converting raw hide or skin into leather which can be used in the manufacture of a wide range of products. Consequently, the tanning industry is a potentially pollution-intensive industry. Chemical impurities mostly comprise of (i). inorganic salt cations such as Fe 2+ , Zn 2+ , Cu 2+ , Ca 2+ , Na + , anions such as SO4 2- , NO3 - , PO4 3- and (ii) inorganic parameters such as Dissolved Oxygen(DO), Total Dissolved Solids (TDS) (Bosni et al 2000). When industrial waste and domestic sewage are discharged into the receiving water bodies without treatment, it leads to increased water pollution, loss of aquatic life and an uptake of polluted water by plants and animals which eventually affect the human body through consumption resulting in health related problems and a degradation of a sustainable environment. Effluents generated by the industries are the major sources of pollution and since most of the human and animal population especially in developing countries do not have access to portable water and in most cases use raw river water for drinking purposes, the quality of life is seriously hampered. Studies on heavy metals in industrial effluents (either in free form or adsorbed in suspended solids) have been found to be carcinogenic (Tamburlini et al, 2002) and other chemicals equally present are poisonous depending on the dose and exposure duration (Kupechella and Hyland (1989)). These chemicals are not only poisonous to humans but are found to be toxic to aquatic life (WHO, 2002) and may result in food contamination (Novick 1999). Study Area The study was carried out from three different areas: on (i) Challawa River with eight sampling stations, (ii) Waste discharges from effluents in the Sharada Industrial Estate such as the Unique Leather Finishing and others discharging into the Salanta river and flowing through Sabuwar Gandu, Kumbotso and entering the Challawa river at Tamburawa. There were a total number of five sampling points here (iii) The third sampling point was from the industries in the Challawa Industrial Estate, made up of Mario-Jones industrial effluent, God's Little industrial effluent, Maimuda industrial effluent, Clobus industrial effluent and Fata industrial effluent and the confluence of the waste discharges from the Challawa Industrial Estate which finally discharged directly into the Challawa River at Yandanko. There were five sampling points at the Challawa Industrial Estate. There were eighteen (18 No) sampling points in all. Other industries in the areas include the textile industries and bottling company. Detailed reconnaissance survey of the study area was carried out to ascertain the sampling points. The survey was made by locating the industrial industries in the estates and following the flow through to the points of discharge on Challawa River. Figure 1 shows a schematic view of the study area. A detailed survey of all the points of wastewater discharge into Challawa river were noted and sampling stations designated 1 to 18 were established as explained earlier