Industrial waste pollution in the Kano river basin

Kano river basin, which serves as the main source of water supply to metropolitan Kano, is also used as receiving body for industrial wastes from Sharada and Challawa industrial estates. Of the three major rivers in this basin, the Salanta river was found to receive the highest pollution from the industrial discharges with COD of 8,557.4mg/l, total solids of 16,934.6mg/l, hardness of 1,349.6mg/l CaCO3, and ammonia nitrogen of 5,150.0mg/l. The Challawa river had COD of 598.7mg/l, total solids of 1,609.9mg/l, hardness of 1,332.0mg/l CaCO3 and ammonia-nitrogen 400mg/l. Both empty into the Kano river where the COD was 1,166.9mg/l, total solids 1,458.0mg/l, hardness 2,506.8mg/l and ammonianitrogen 530mg/l. Although these rivers are being used extensively for water supply, irrigation, and fishing, the quality of the water was found to be unsuitable for these purposes. The paper suggests that waste water pretreatment by all industries, imposition of direct charges on industrial effluents by the regulating agency, as well as continuous monitoring and surveillance are required to ensure the protection of the water resources in the basin. M.H. Bichi Lecturer, Department of Civil Engineering, Bayero University, Kano, Nigeria B.U. Anyata Associate Professor, Department of Civil Engineering, University of Benin, Benin City, Nigeria Industrial waste pollution in the Kano river basin [ 112 ] Introduction Industrial waste and water resources pollution The world industrial development is increasingly necessitating focus on the problems of the environment. Water resources is one such environment continually being threatened with devastation by industrial wastes. In third world countries, the industrial pollution problems are comparable to those in the industrialized nations (Hardoy et al., 1992). The Global Environmental Monitoring System (GEMS) of the United Nation Environmental Programme (UNEP) has reported heavy pollution in several rivers in Chile, China, Japan, Mexico, Panama, The Philippines, and Turkey (UNEP, 1991). In Nigeria, Olurontola (1990) has reported gross industrial pollution in Ologe Lagoon; Nwaogazie (1990) has recorded textile effuent pollution in Imo and Bonny Rivers in Port Harcourt; and Beecroft et al. (1987) have reported that untreated industrial effluents constitute up to 75 percent of the dry season flow of the River Kaduna. UNDP (1978) and Bichi (1993) have indicated that the dry season flow of River Jakara in Kano is almost entirely made up of sewage and industrial waste discharges. Industrial wastes in the Kano River basin Kano City is located on the main water shed which separates the two main river basins in the metropolis (Figure 1). The Jakara River basin in the North comprises the Jakara River and its main tributaries – Gogau, Tukurawa, Govagwarwa, Rafin Mallam, Tsakama, Cijaki, and Getsi. The Kano river basin lies to the south of the water divide. The basin is being drained by Rivers Kano, and Challawa, and their tributaries – Watari, Y’arkuto, Tatsawarki, and Salanta. The main industrial areas of Kano – Bompai, Sharada, and Challawa – are located within these two river basins. In the Kano river basin, Rivers Salanta and Tatsawarki remove the waste waters from the entire Southern part of Kano (Figure 2). In addition, all the waste waters from the Sharada and Challawa industrial estates are drained by this basin. According to the Ministry of Trade and Industry (1990), Challawa and Sharada industrial estates comprised of 14 tanneries, 11 textiles, and over 20 food processing industries. In addition, there are 30 aluminium, metal and wood processing factories; 25 plastics, rubber and tyre factories; and over 15 chemicals and cosmetic products industries. Most of these industries do not have adequate waste treatment facilities. The basin, besides being used for extensive irrigation of rice, wheat, and vegetables, is the main source of water for metropolitan Kano, serving a population of 2.8 million people. The Challawa water works, which has three treatment plants, derives its raw water from this basin. The 10M lpd plant uses surface water from River Challawa; the 120M lpd second plant uses surface water from Kano River; and the 90M lpd third plant utilizes ground water from the Kano river bed. The Tamburawa treatment plant with a capacity of 30M lpd is supplied from tube wells drilled into the Kano river bed just after the Challawa-Salanta confluence (Figure 2). The 30M lpd Wudil plant is also supplied from tube wells drilled into the Kano river bed at Wudil. The increasing discharge of industrial wastes in this river basin is posing serious danger to the water resources and the health of the people in the area. Aim of the paper The paper aims to assess the quality of water in the three main rivers in the Kano river basin and their suitability for the various uses to which they are put. The paper will attempt to identify the causes of pollution in the basin, and suggest ways of minimizing the problem.