Chemical characterization and comparison of nutrient quality of abattoir, and industrial solid waste from Kampala city, Uganda

Abstract

Waste water treatment is a fundamental component of any society to safeguard people‟s health from water bone and water related diseases. Wastewater treatment results into discharge of sludge (Sludge is a concentrated suspension of solids resulting from waste water treatment) that can be used as organic fertilizers to replenish lost nutrients in soil. This study was conducted to characterize and compare chemical properties and nutrient quality of solid waste and industrial sludge from Kampala City Abattoir, National Water and Sewage Corporation and Uganda Breweries. Twelve samples were randomly collected from every study station and analyzed for pH, total P, N, O.C and basic cations (K+, Ca2+, and Na+). Data were analyzed using Genstat Statistical Package 12th Edition. The impact of source of sludge on pH, Calcium and Sodium was significant. However, source of sludge had no significant effect on potassium. The pH of solid waste from National Water and Sewage Corporation (8.0±0.04) was significantly higher than that of brew residues from Uganda Breweries (7.2±0.05). Age of Abattoir waste had no significant impact on pH, with the highest average pH being 8.11±0.28 (in maturing Abattoir waste) and the lowest being 7.56±0.28 (from mature sludge). There was also no significant impact of source of sludge on Organic carbon (OC), N and P. However, the %OC of sludge from National Water and Sewage Corporation (15.52±11.90)% was higher than that of Uganda Breweries (6.2±6.9)%. The Phosphorous content of sludge from Uganda Breweries (0.131±0.0295)% was higher than that of NWSC (0.104±0.04)%. Although there was no significant impact of age of sludge from Kampala Abattoir %OC and %N, their concentrations were higher (20.4±9.36)% OC and (0.94±0.481)% N in mature sludge than observed for maturing sludge (6.6±5.43)% OC and (0.26±0.481)% N. Mature sludge tended to have highest (0.294±0.169)% phosphorous content and the lowest (0.060±0.0230)% phosphorous concentration was observed in settling sludge. Generally, all these bio-solids have nutrient levels above recommended international bodies and other researchers. Sludge storage from NWSC plant Bugolobi and Kampala Abattoir should be improved so as to minimize nutrient loss by leaching and volatization.