Codigestão de dejeto suíno e carcaça suína hidrolisada

Abstract

Pig farming is a production system that has evolved and adapted all over the world. To meet the environmental parameters and ensure the herd’s sanitary status, new strategies for the treatment of waste generated during the production process are being researched, particularly in relation to swine mortality waste, which represents a greater potential risk to animal and human health within the unique health spectrum. Biodigesters are one option for treating these residues within the confines of rural property. This strategy enables waste treatment in the same reactor (co-digestion), lowering costs and producing biogas and biofertilizer at the same time. However, some considerations must be made when treating waste from non-slaughtered dead animals, which may contain pathogenic microorganisms. Thus, pre-treatment of the carcasses is required before use in anaerobic reactors and subsequent agricultural use of the digestate. Therefore, this study examined the effects of pre treatment of swine carcasses through enzymatic hydrolysis on pathogen deactivation and subsequent use of the hydrolyzate as substrate in co-digestion with manure in a Covered Lagoon Biodigester (CLB) and Continuous Stirred Tank Reactor (CSTR) on a laboratory scale. The inactivation of pathogens after pre-treatment of carcasses was evaluated, using Escherichia coli, Salmonella spp. and Porcine circovirus type-2 (PCV2) as bioindicators. The pre-treatment was effective in inactivating E. Coli bacteria. The reactors used in the experiment have a useful volume of 12 L and an operating volume of 17 L. The CSTR reactor has a 15 minutes’ shift stirring system at 55 RPM and heating at 37°C. Due to their unique characteristics, each reactor was subjected to a different set of operating conditions. However, both started operations fed with only swine manure, and the Organic Load Rate (OLR) progressions with the addition of hydrolyzed swine carcasses were performed whenever the reactors showed a variation < 10% in biogas productivity, for 5 consecutive days. The OLR progressions in the CSTR lasted five phases, starting at the OLR of 0.42 kgVS.m-3.d-1 and had its best performance in Phase IV, at the OLR of 2.09 kgVS.m-3.d-1, with an average productivity of 1.12 LN CH4.Lreactor-1.d-1. The OLR progressions in BLC lasted eight phases, starting at the OLR of 0.13 kgVS.m-3.d-1 and had its best performance in Phase VII, at the OLR of 0.63 kgVS.m3.d-1, with average productivity of 0.31 LN CH4.Lreactor -1.d-1. The use of hydrolyzed swine carcasses in co-digestion with manure demonstrated a high potential for CH4 production, in CSTR the productivity increased about tenfold, while in CLB, productivity increased about fourfold, compared to phase 1.