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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 .

Food waste represents a relevant fraction of municipal solid organic waste, and anaerobic digestion can be an eco-friendly alternative for sustainable management in a circular economy framework. One of the challenges to the implementation of anaerobic digestion is the availability of easily degradable compounds in the substrate, which can be solved by the application of pretreatment to increase methane production. In this study, the influence of aerobic storage time and forced continuous aeration pretreatment on the biochemical methane potential of food waste was evaluated. The results demonstrate an increase in the methane production concerning the total volatile solids (TVS) of food waste stored for 7 days (425 NmL CH 4 g −1 TVS) compared with fresh samples without pretreatment (375 NmL CH 4 g −1 TVS). The adoption of forced and continuous aeration pretreatment on food waste for 4 days produced 456 NmL CH 4 g −1 TVS for the leachate, 1.22-fold higher than that for the food waste without storage. In conclusion, the application of aeration pretreatment previous to anaerobic digestion can be an alternative to increase the methane potential from food waste.

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