Biogas production using coagulation sludge obtained from paint wastewater decontamination: Characterization and anaerobic digestion kinetics"
Marcel I. Ejimofor, I.G. Ezemagu, Matthew C. Menkiti
Abstract
This work focuses on the characterization and conversion of post coagulation sludge (PCS) from paint wastewater coagulation using nano Konki-De into biogas. Paint wastewater, snail shell flour (SSF) and PCS were used as raw materials. The nano konki-De (crude protein) extracted from SSF sometimes referred to as coincholin was used as the coagulants, while the PCS recovered after coagulation process was used for the biogas production. Modified Fernadez-Kim method, Jar test experiment and anaerobic digestion were used for bio-coagulant extraction, wastewater treatment and biogas production, respectively. SEM-EDX, FTIR and XRD studies were undertaken, to understand the structure, composition and crystalline nature of nano Konki-De and PCS. The biogas was characterized using gas chromatography (GC). Premised on experimental and instrumental analysis, the active ingredient in SSF was found to be Nano Konki-De, a chitno protein. Paint wastewater contains 2598 mg/L total suspended particles and 110 mg/L total dissolved solids in excess of NERS standard. The post coagulation sludge contains total solid of 222 g/L, high volatile solid content (76% total solid) and carbon to nitrogen ratio of 25:1. The actual gas production started after the lag period of 4 days. Maximum daily yield of 80 mL was obtained at the 20th day while the cumulative yield of 250 mL was recovered within the retention time. The kinetics of bio-fermentation process followed logistic models amidst the five kinetic models investigated.