Effluents Composition: A Function of Industry Types in Southwestern Nigeria

Abstract

Introduction The rapid growth of industry types has resulted in increased discharge of effluents into water bodies. Aim The study aimed at establishing a pattern in effluent load according to industry types in Lagos metropolis. Materials and methods The industry types studied were pharmaceuticals, textiles, paints, foods and beverages, basic metals, and conglomerates. Effluent samples were collected bimonthly over a period of 20 months. Total Dissolved Solids (TDS), pH, alkalinity, total hardness, sulphate, phosphate, nitrate, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and heavy metals were determined in the effluents according to APHA methods. Result Physicochemical characteristics (mg/L) of effluents from textile and pharmaceutical industries were 1160±890 and 630±260 for TDS, 316±280 and 230±97 for alkalinity, 60±32.and 53±44 for total hardness, 156±73 and 34±36 for sulphate, 1.0±0.3 and 0.7±0.6 for phosphate, 60.0±40.0 and 75±45 for nitrate, 1.8±1.7 and 1.3±1.2 for DO, 209±72 and 150±96 for BOD, 343±130 and 245±140 for COD, 0.7±0.3 and 0.5±0.2 for Zn, 1.5±1.0 and 0.3±1.1 for Cu, 2.5±0.3, 0.03±0.03 for Cr and corresponding pH was 10.6±1.1 and 5.5±1.2 respectively. Effluents from other industry types had lower levels of TDS, alkalinity, phosphate. Conclusion The results showed textile and pharmaceutical industries having higher pollution load in pH, BOD and COD.