Coliforms and enterococci as indicators of faecal pollution of Woji River receiving abattoir effluents in Port Harcourt, Rivers State Nigeria

Abstract

This study assessed the influence of the abattoir effluents and other human centred activities on the microbial quality of the Woji Trans-Amadi River of Port Harcourt, using coliforms and enterococci as indicators of faecal pollution. Four sites on the Woji River namely: the abattoir effluent, the waste/faeces disposal, upstream and downstream sites were monitored for total coliforms, enterococci, total heterotrophs, biochemical oxygen demand (BOD), pH and salinity. Total coliform numbers varied from 2.0 x 10⁶ MPN/100ml to 1.70 x 10¹⁰MPN/100ml with the highest values of 1.70x10¹⁰ MPN/100ml and 4.70x10⁸cfu/100ml at the abattoir and waste sites respectively and the lowest values of 2.0x10⁶⁵ cfu/100ml at the upstream and downstream respectively. Lower numbers ranging from 3.00 x 10⁵cfu/100ml to 2.00 x 10⁷cfu/100ml were obtained for enterococci similarly at the respective sites, and the range of values from 3.7 x 10⁵to 1.8 x 10¹⁰ cfu/100ml were obtained for total heterotrophs. Bacterial numbers were higher at all the sites during the dry season compared with the rainy season. The BOD varied from 2mg/l at the upstream site to 360mg/l at the abattoir effluent site; and similarly the pH level varied from 6.22 to 7.36 and the salinity from 2879mg/l to 13898mg/l at both sites respectively. None of the sites achieved internationally accepted standards for water quality of Rivers. The results of this investigation revealed that Woji River is subject to sewage pollution and is impacted from the abattoir effluent site and waste/faeces site.

Key Words: Coliforms, Enterococci, Abattoir effluents, Woji River, Faecal Pollution, Biochemical Oxygen Demand.