Produção de biogás a partir da co-digestão da fração orgânica dos resíduos sólidos urbanos e resíduos de hortifrutigranjeiros

Abstract

Anaerobic digestion (AD) of waste is an environmentally sound option for the treatment of organic waste and produce biogas. However, the process efficiency is influenced by several factors, including the composition of the substrate. Fruit and vegetable waste (FVW) have suitable physicochemical properties for use as an energy source. However, the high content of simple sugars contained in fruits and vegetables tend to acidify, inhibiting the activity of methanogens. The co-digestion of wastes is an alternative to improve process stability. The organic fraction of municipal solid waste (OFMSW) also has great energy potential that can be recovered, and when co-digestion with FVW, biogas production can be increased. In this context, this study aimed to evaluate the production of biogas from the co-digestion of OFMSW with FVW, to establish a great proportion where biogas production is maximum, without damage to the process stability. The study was conducted in four phases, batch system at 35 ° C, using anaerobic sludge as inoculum in the ratio S/I 1/1 in terms of the total volatile solids (VS). The VS mass added in the reactors was the same in all conditions. Were tested OFMSW (Phase I) and FVW (Phase IV) as mono- substrates and co-digestion of these wastes in relationships OFMSW/FVW 1/1 (Phase II) and 1/3 (Phase III) in terms of VS. The monitored parameters were pH, total and volatile solids, total organic carbon, alkalinity, volatile fatty acids, volatile organic acids and volume of biogas. Biogas was characterized as methane levels. Waste applied in co-digestion and the final biosolids were analyzed for pH, total and volatile solids content, total organic carbon, alkalinity, volatile fatty acids, volatile fatty acids, and total ammonia nitrogen and total phosphorus. The AD process remained stable in all power conditions. The results show that biogas production was higher in batches where OFMSW and FVW were applied by co-digestion in relation to batches that used OFMSW and FVW as mono-substrate. The relationship OFMSW/FVW of 1/3 produced the highest volume of biogas and obtained the higher yield of methane due to the VS applied to waste, being 493,46 NL/kgVS and 393,64 NL/kgVS respectively.