Effect of Blended Activated Charcoal–Calcium Carbonate Filler on the Treatment of Abattoir Effluent

Abstract

Abattoir effluent is a major source of environmental contamination in developing nations due to its high organic, microbial, and heavy metal load. This study investigates the treatment efficiency of blended activated charcoal–calcium carbonate filler at different ratios (1:1, 2:1, and 1:2). Effluent samples collected from the Warake Road Abattoir in Auchi, Nigeria, were analyzed for physicochemical, nutrient, heavy metal, and microbial parameters following APHA standards. The results showed marked improvements under the 1:2 blend, including BOD and COD reductions of 78% and 80%, TSS and turbidity reductions of 62% and 85%, phosphate reduction to within permissible limits, and over 90% microbial reduction. However, residual BOD (68 mg/L), COD (180 mg/L), oil and grease (12 mg/L), and microbial counts still exceeded Nigerian Industrial Standards (NIS), indicating incomplete compliance. Furthermore, iron concentrations increased dramatically from 0.12 mg/L to 1.48 mg/L, nearly five times above the <0.3 mg/L standard; this observed leachate resulted from the coagulant, iron chloride, used on the filtrate. While the blended filler demonstrates promise as a low-cost pre-treatment option, its use as a standalone solution is not feasible. Instead, it should be integrated into a multi-barrier treatment system involving biological polishing and final disinfection for full compliance. Future research should prioritize dosage optimization, mitigation of iron leaching, economic evaluation, and management of spent filler materials to ensure long-term sustainability.