Estudo das variáveis físico-químicas e dos microrganismos da codigestão do efluente de laticínio com esterco bovino para a produção de biogás

Abstract

During the production stages of the dairy industry, liquid waste is generated with a high organic load considered potentially polluting. Therefore, anaerobic digestion can be an alternative to treat this effluent. However, given the high biodegradability of this substrate, this biotechnology may have some disadvantages. It accumulates organic acids, resulting in the inhibition of methanogenic archaea, and leading to digester failure and lower biogas production. A solution for non-acidification is using cattle manure in co-digestion with dairy effluent. This work aimed to study the physical-chemical variables and the methanogenic microbiota of the co-digestion of dairy effluent with cattle manure for biogas production. For this, anaerobic co-digestion tests were carried out on the two substrates in benchtop anaerobic reactors, in a batch process, with the reuse of sludge from the previous feeding. The synergistic effect of dairy effluent with cattle manure, the potential of adaptation of sludge to effluent, the characterization of predominant microorganisms, and the quantification of consumed carbohydrates and produced organic acids were evaluated. The dairy effluent mixture and cattle manure did not show adequate alkalinity for the methanogenic consortium development. However, the system showed an inherent capacity to acquire alkalinity over time, presenting a greater balance in the process. Despite obtaining total alkalinity and pH values for the stability of anaerobic co-digestion, there was a low -production of biogas, indicating the need for a longer period of adaptation of microorganisms from cattle manure to dairy effluent for better methanogenic activity.