Post by : Chui Chui Goh
Water Pollution - Of all natural resources, water is the most severely threatened by pollution. The Department of Environment (DOE), Malaysia reports the most serious water polluting industry in terms of the number of point sources. In this context, food processing is the most polluting industry for water. The deterioration of water quality follows a five-year trend (1986-1991). The trend indicates that the number of rivers in the slightly polluted and very polluted categories is tending to increase while the number of rivers in the clean category is tending to decrease. Water pollution in Malaysia is measured in terms of BOD caused by organic pollution, ammoniacal nitrogen (NH3-N) emitted in the form of sewage and animal waste or fecal coliforms), suspended solids for soil erosion and sedimentation. Heavy metals and nutrients are also measured. The DOE no longer gives information on the most important polluters of water by pollution load. Instead, information is presented according to the number of polluters. Malaysian rivers are heavily polluted with mean BOD levels nearly six times the international standard. Residential sewage accounts for nearly 80 percent of BOD-related water pollution, followed by agriculture and industry. Inadequate sewerage system is the main cause of water pollution.
The principal source of fecal coliforms is human waste, while concentrated industrial wastewater and agricultural run-off of fertilizer and chemicals into surface water affect levels of dissolved oxygen in water. The reduction of dissolved oxygen effects mainly plant life and fish resulting in destruction of aquatic life and the natural ecology of the rivers. Forest harvesting and agricultural and urban development have resulted in the pollution of most river systems, affected ecological dynamics and disrupted natural food chains. In 1991, 40.5% of the 2,292 industries in Malaysia, identified as major sources of water pollutants, were food and beverage industries. 14.1% were rubber producing and 11.8% were chemical producing industries. In terms of organic water pollution, human and animal wastes largely from piggeries and agro-based industries are the primary sources. The heavily industrialized Peninsular states that are most affected by these pollution sources are Selangor, Johor, Penang and Perak. Although the supply of clean water is high, inadequate sewerage and drainage systems now threaten water quality.
Further clearing of forested land, tin mining and effluent discharges from industries, tin mining, logging, use of weedicides, insecticides, latex processing plants and manufacturing industries are polluting surface water sources. Treatment of raw water from surface water sources for human consumption and for industrial use has become more complex because of water pollution.