Pig faeces digestion as compared to anaerobic co-digestion using waste waters sludge or bovine ruminal gastric content treatments

Anaerobic co-digestion improves the pig faeces digestion process. This work presents anaerobic digestion of pig faeces (C) as compared to 2 co-substrates: Sludge (L) from waste waters and bovine ruminal gastric content (R). Pig faeces used were generated in a local farm at the Juarez Autonomous University of Tabasco (UJAT), with a total population of 148 animals. Analytical determinations were made on the substrate and co-substrates. Each treatment was performed in triplicate (9 experimental units), for 18 weeks. C+R co-digestion had the highest removal of chemical oxygen demand (COD) with 90%. Biogas production (0.012 L day-1) was quantified for C and C+R, with concentrations of 70.87±8.65 and 71.89 ± 7.60% of methane (CH4), respectively. For C+L, it was 0.009 L day-1, with 77.89±6.74% of CH4. Results obtained showed that co-digestion of C+L was better with regards to the quality of biogas from low hydrogen sulfide (H2S) concentrations (70.33±6.36 ppm). The use of anaerobic co-digestion systems represents an alternative treatment for faeces generated in pig farms and other kinds of wastes to reduce the potential source of infection produced by these types of waste.   Key words: Biogas, digester, manure, pig faeces, rumen.