Assessment of selected parameters for industrial effluents from some industrial sites in Nairobi, Kenya

Abstract

Abstract The discharge of industrial effluents into the environment poses a threat to human health and is of environmental concern to both plants and animals. Over the last several years there has been a great deal of pollution caused by sewerage treatment works and industrial plants discharging effluents into the environment. This has been caused to a large extent by rapid population increase in the cities and towns, which has led to a strain on the plants’ capacities. The industrial effluents from selected industries in Nairobi’s Industrial area, Kenya were analyzed to determine the physico-chemical properties which were then compared to the guidelines of the National Environment Management Authority (NEMA). The effluents were collected from four different industrial sites namely General Plastics Industries Ltd., Bhachu Industries Ltd., Chloride Industries and Sameer Africa. pH, color, temperature, chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS) and oil and grease were analyzed using standard analytical methods. The results in range form for the four sites were as follows: pH 7.4- 8.7; colour 26-44 Hazen units; temperature 20.5- 27.7 0C; COD 22.22-96.30 mg/L; TSS 25.00-26.37 mg/L; TDS 1080.7-1225.3 mg/L; Oil and Grease 5.71-12.52 mg/L. pH, colour, and oil and grease for effluent outside Sameer Industries were above NEMA guideline values for discharge into the environment. General Plastic Industries had colour, total dissolved solids and oil and grease all above NEMA guideline values. Colour, total dissolved solids and chemical oxygen demand outside Bhachu Industries were also higher. At Chloride Industries only colour was above the guideline value. There is therefore need to use appropriate treatment methods to lower these values. Keywords Industrial Effluent, Physico-chemcical Parameters, Industrial Sites, NEMA Standards