Impact of industrial cassava effluent discharge on the water quality of Ogbese river, Ayede-Ogbese, Ondo state, Nigeria

Abstract

Impacts of cassava effluent discharge on physicochemical parameters of water quality were assessed using standard procedure. Results showed TDS ranged (108.00 ± 28.2 – 110.50±27.5 mg/L), 123.50 ± 31.82-310.50 ±184.56 mg/L) and (114.00 ±31.11 - 115.50 ±30.41 mg/L) for UWS, DPWS and DWS respectively. TSS in the effluent samples were 1287.50 ±137.89 mg/L and 19942.00 ±2791.08 mg/L during wet season and 1925.00 ±0.00, 21942.00 ±0.00 mg/L in dry season respectively. Highest BOD (61.5±6.36 mg/L) was at discharge point during wet season and lowest (0.35±0.07 mg/L) was downstream during dry season. In wet season, the BOD ranged (2.00±0.5 - 3.20±1.13 mg/L) upstream was lower relative to downstream range (26.00±5.66 -36.00±21.21 mg/L). pH of water ranged (7.43±0.46 -7.85 ± 0.78) and (6.55±0.78 - 7.05±0.21) upstream and downstream respectively during wet season while pH ranged (7.15± 0.21- 7.35± 0.21) and 6.70 ± 0.00 – 6.90± 0.00) upstream and downstream respectively in dry season. At discharge points pH ranged (5.90±0.00 – 6.50 ± 0.42). Electrical conductivity (E.C.) in wet season has lowest value 191.50±54.45 - 192.50 ±50.20 µScm upstream and also lowest compared with all locations in dry season. Acidity of water ranged (30.00±8.49 - 45.00±26.87, 15.00±1.41 - 16.00±2.83 and 80.00±8.49 – 4,320.00 ± 4.24 mg/L) respectively for downstream, upstream and discharge point in wet season. However range of acidity values in dry season were (30.00±0.00 - 43.00± 1.41, 20.00 ± 70.00 – 32.50 ± 0.71 and 47.50 ± 13.44 – 5750.00 ± 70.71 mg/L) for downstream, upstream and discharge point respectively. Results indicated that water quality of downstream was impaired compared to upstream and season dependent, suggesting significant pollution from cassava effluent discharges. The effluent instilled unsightly, nauseating and undesirable effects on biotic community and rendered water useless for any domestic usage. Continuous monitoring of Ogbese River is imperative for future sustainability of the river.

Key Words: Water quality, Effluent, Physiochemical parameters, Permissible limit