Abstract:

A study was conducted to characterize wastewaters from Sky fat and Leather tannery of Uganda - LIU) to assess for compliance to safe limits; impacts on the habitat of Nile Tilapia and also assess for chromium bioaccumulation. The two tanneries are located in Jinja Municipality within Kirinya West Wetland along Napoleon Gulf of Lake Victoria. Effluent, water, sediment and fish specimen were collected from georeferenced sites once every month for six months covering the dry (December to February) and wet (March to May) seasons. Data on some physicochemical parameters were collected in-situ using calibrated water quality meters. All samples were processed and analyzed for chromium using standard methods (API1A, 1999). According to the results, the physico-chemical quality of the effluents significantly exceeded the permissible limits. High pH (7.5 to 9.6), EC (626 to 12,130 pS/cm), TDS (419.4 to 8,127.1 mg/L), low dissolved oxygen (0.1 to 1.1 mg/L) and redox potentials were recorded. Cr was significantly high (Tukeys HSD test, p < 0.05) exceeding the permissible limit of 100 pg/L (NEMA, 1999; USEPA, 2003) by approximately 50 limes. Elevated Cr concentrations in water (0.1 to 126.9 pg/L) and sediment (range 17.9 to 135.7 pg/g dwt) were noted. A high geoaccumulation index (Igeo = 3.58) and sediment enrichment (55.1) factor were recorded indicating sediment contamination. Cr bio-accumulation in fish organs (range 0.18 to 2.33 pg/g dwt) occurred in the order of liver > skin/muscle > gill. The poor effluent quality is a potential health risk to the fishery and the people.