Slaughterhouse by-products treatment using anaerobic digestion

摘要

Highlights•The investigated slaughterhouse by-products had high degrees of biodegradability.•Substrates of higher fat content generated larger amounts of methane.•Co-digestion of animal by-products with agroindustrial waste proved to be feasible.•Orange peels were proved to be a better co-substrate compared with olive leaves.•The highest methane yields were obtained for an organic loading rate of 0.8gVS/L/d.AbstractThe objective of the present study is to evaluate the use of animal by-products (ABP) as substrates for anaerobic digestion, aiming at methane production. Specifically, four ABP of Category 2 and 3, namely (i) stomach and rumen, (ii) stomach contents, (iii) breasts and reproductive organs and (iv) bladders and intestines with their contents, were selected. The methane potential of each ABP was initially determined, while the feasibility of anaerobic co-digestion of ABP with two agroindustrial waste, i.e. orange peels and olive leaves was also studied. To this purpose, Biochemical Methane Potential (BMP), as well as semi-continuous assays were respectively conducted. In the latter, the effect of the variation in the organic loading rate (OLR) on methane production was investigated. Results obtained from BMP assays showed that the samples containing breasts and reproductive organs, bladders and intestine, and stomach and rumen, had higher methane potentials of 815, 787 and 759 mLCH4,STP/gVS, respectively. Moreover, according to the results of the semi-continuous assays, maximum methane yields between 253 and 727mLCH4/gVSfedwere obtained at an OLR of 0.8gVS/L/d. The only case in which methanogenesis inhibition phenomena, due to increased ammonia concentrations, were observed, was the assay being fed with a mixture of breasts and reproductive organs and orange peels, at the highest OLR. This inhibition phenomenon was attributed to an inappropriate C/N ratio.