Abstract
The rapid pace and scale of urbanization in Nigeria has led to large volumes of domestic and industrial wastes, which pose threats to the environment and public health. Currently, in Nigeria, there seems to be neither sufficient measures nor facilities to treat abattoir effluents for environmental safety or to recover usable energy and material from abattoir by-products.
This study was conducted to assess the microbial status of the Lafenwa abattoir effluent and its receiving surface water. The Total viable and Coliform counts (TBC and TCC) using surface plating and multiple tube test techniques, respectively were performed. Bacterial contaminants were isolated and identified by standard microbiological procedures. Furthermore, various methods for waste disposal at the abattoir were assessed. The mean TBC and TCC for waste water during and after slaughtering were 5.2x107, 4.9x107 and 4.26x107, 3.06x107 cfu/ml respectively. The receiving surface water had mean TBC and TCC of 4.15x107, 3.83x107, and 3.89x107, 2.87x107 cfu/ml respectively. Waste disposal in the abattoir was by open dumping of solid wastes while effluent was discharged into the nearby Ogun River, which is also used by butchers for meat processing. Bacterial organisms isolated from the effluent include Enterobacter aerogenes, Hafnia alvei, Erwinia mallotivora, Edwardsiella ictaluri, Enterobacter amnigenus and Escherichia coli O157strains while Proteus miriabilis, Staphylococcus spp, Pseudomonas aeruginosa, Enterobacter intermedius, Yersinia aleksiciae, Serratia odorifera, Enterobacter cloacae, Enterobacter aerogens and Eschericia coli O157 strains were isolated from the surface water.
The high microbial load and the isolation of pathogenic organisms of public health importance especially Escherichia coli O157 strains further demonstrates the need for adequate waste disposal and treatment. Also, the current methods of waste disposal at the abattoir greatly reduces the quality of the surrounding environment and portends a risk to public health and food safety.

Key words: Bacteriology; Abattoir; Waste water; receiving surface water; Public health.