Abstract

Meat rendering represents one of the most important sectors of the meat industry in Australia. With industrial growth, there has been increased attention to waste management of meat wastes. One of the alternative waste management technologies attracting the meat industry attention is anaerobic digestion (AD), especially that renewable energy and cost savings are added benefits. In this study, the feasibility of anaerobic digestion of wastes generated at a meat rendering plant in Melbourne was investigated. The plant uses dissolved air flotation (DAF) to treat the wastewater before discharge to the sewer. The sludge separated is sent to landfill. The waste samples tested were collected upstream and downstream ends of the DAF unit. Biogas production in reactors fed with the wastes, raw wastewater, DAF-sludge, DAF-supernatant and a mixture of DAF-sludge and DAF-supernatant, representing organic loadings of 0.9, 0.1, 5.1 and 2.6 gCOD/gTS, respectively, was measured. The raw wastewater (organic loading of 0.9 gCOD/gTS) showed the highest cumulative biogas production (CBP) of 0.287 m³ biogas/kgTSadded. The CBP in the reactors fed with DAF-supernatant, DAF-sludge and mixture of DAF-sludge and DAF-supernatant were 0.188, 0.0653 and 0.0634 m³ biogas/kgTSadded. The performance of the reactors fed with DAF-sludge indicated inhibition conditions to biogas production prevailed during the first two weeks. The biogas produced from all reactors, except those fed with DAF-sludge, showed high methane content throughout the experimental period ranging from 75% to 85%. However, the methane produced from DAF-sludge was initially lower at 45%-48% days 8 to 15, and then increased to 70% - 75%, from day 19 till the end of the experimental run. This study showed that meat wastes have a high potential for methane gas production for renewable energy.