Abstract

This study focused on the impact of Abattoir effluent on the dissolved oxygen (DO) of Ikpoba River with a special interest on the critical oxygen deficit and its time of occurrence. Abattoir effluent and river water were sampled for some physico-chemical parameters analysis. River flow velocity and depth were also determined. These parameters were inputted intoO’Connor and Dobbins; and Streeter and Phelps models to generate the requisite outputs. The re-aeration and de-oxygenation rates were 0.28 day-1and 0.37 day-1; the biochemical oxygen demand (BOD) of effluent, river’s upstream and downstream were 108.4, 2.2 and 4.6 mg/l, respectively. The critical oxygen (Dc) deficit was 5.7 mg/l at 0.61 days and the minimum DO was 2.4 mg/l. This revealed a high effluent and downstream BOD with serious impact on the river DO. Consequently, the de-oxygenation rate in the river dominated the re-aeration rate and portrayed the river to be in danger of pollution. However, the study showed that the river’s self-purification capacity was not overwhelmed. The effluent treatment facilities were recommended to reduce the effluent BOD load and the consequent self-purification stress induced on Ikpoba River.