Co-digestão anaeróbia e aeróbia em diferentes proporções de resíduo de incubatório e dejetos de ovinos

Abstract

This study was carried out to evaluate the effects of adding hatchery liquid waste (HLW) in anaerobic co-digestion of sheep manure and to evaluate the addition of hatchery solid waste (HSW) on the efficiency of co-composting with sheep manure. Analysis was carried out using a completely randomized experimental scheme. Co-digestion was done adding three levels of HLW (0; 10; 20) and 30% of HLW, related to the total solids content (TS). Co-composting was evaluated using several levels of HSW (0 10; 20; 30; 40; 50%), related to the piled fresh mass. The variables measured during anaerobic co-digestion were related to the losses of TS and volatile solids (VS), the generation of specific biogas and methane production, and the content of methane present in the biogas. The most expressive reductions of TS and VS (40.9 and 50.2%), showing linear distribution, values 35.9 and 26.5% higher than those observed with 0% HLW inclusion treatment. The largest specific biogas productions were 249.9 (TS) and 286.4 L.kg-1 (VS). The highest specific production of methane was 171.9 (TS) and 199.7 L.kg-1 (VS). The inclusion of 17.6% showed the greatest content of methane in the biogas (69.7%). The variables measured in the process of co-composting were related to temperature, the most likely number of total and thermos tolerant coliforms (MPN), TS, VS, neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose and levels of nitrogen (N). The results regarding temperature were similar among piles. The elimination of coliforms was observed in all treatments. The most considerable reductions of TS and VS were observed using 26 and 29% (HSW), respectively. These were 22 and 15% superior to the piles prepared only with sheep manure. The greatest reduction of NDF (61%) was found adding 20% of HSW, which was 10% higher than the reduction observed in the control group. The reduction of hemicellulose was 13% higher than the initial treatment, adding 23% of HSW. The most considerable reduction was 80%. The addition of 20% of HSW generated concentrations of N above 5% in the compost. This dose was also related to the highest retention among treatments. The inclusion of HLW and HSW in sheep manure improved anaerobic co-digestion and co-composting.