Anaerobic Digestion of Food Waste Using UASB Sludge from a Poultry Slaughterhouse as Inoculum

Abstract

Abstract:In 2010, Brazil endorsed a new national policy of solid wastes, which has a very ambitious target to close up all the dumping areas and to manage adequately all the municipal solid waste, disposing in landfills only the refuse of treated municipal solid waste after 2019. Food waste is the largest representative of organic waste produced in Brazilian municipalities, which can produce both fertilizer and biogas through anaerobic digestion (AD) process, reducing in both cases greenhouse gases emissions. AD assays of some samples of restaurant food wastes were performed in batch laboratory, 500 mL reactors for determination of optimized start-up conditions. The tests were conducted in triplicate, using anaerobic sludge from a poultry slaughterhouse wastewater treatment as inoculum to start up the anaerobic biodigestors. The effect of three different substrates to inoculum mixing ratios 10:90 (S 1 ), 20:80 (S 2 ) and 30:70 (S 3 ) was evaluated. The food waste used as substrate was previously homogenized and submitted to aerobic mechanical mixing for four days before it was fed in the reactors in anaerobic conditions at the mentioned proportions with the inoculum. The reactors were maintained at 35 °C and under mechanical mixing at 60 rpm. The methane production was monitored until its stabilization. Results showed that S 1 presented the best performance during the initial 12 d, when it totalized 526 NmLCH 4 /gVS substrate .