Anaerobic co-digestion of animal manure at different waste cooking oil concentrations

EnglishThis study aimed to obtain the best dose of waste cooking oil inclusion for the co-digestion of substrates prepared with dairy cattle and swine manure in order to maximize solids reductions and biogas yield. Analyses of total solids (TS), volatile solids (VS), and neutral detergent fiber (NDF) were performed during the loading and unloading of digesters, while biogas yield was measured twice a week. The maximum reduction in VS (51.4%) was reached with the inclusion of up to 54.6g waste cooking oil.kg manure-1. Maximum NDF degradation occurred with inclusions of up to 69.4g waste cooking oil.kg manure-1. Inclusions of up to 64g of waste cooking oil.kg manure-1 provided specific biogas yield of 291.4 and 251.0L biogas.kg VS-1 added to substrates with swine and cattle manure, respectively. Adding oil at doses between 45.1 and 69.4g waste cooking oil kg manure-1 to substrates composed of cattle or swine manure maximizes reductions of solids and fibrous constituents and enhances specific biogas yield. Furthermore, swine manure supports higher doses of waste cooking oil. Key words: digestion; biogas; energy recycling portuguesObjetivou-se encontrar a melhor dose de inclusao de oleo residual durante a co-digestao de substratos preparados com dejetos de bovinos leiteiros e suinos, com o intuito de maximizar as reducoes de solidos e as producoes de biogas. Foram realizadas no abastecimento e desabastecimento dos biodigestores as analises de solidos totais (ST), solidos volateis (SV) e fibra em detergente neutro (FDN), enquanto as mensuracoes de biogas duas vezes por semana. A maxima reducao de SV (51,4%) foi possibilitada pela inclusao de ate 54,6g de oleo de descarte kg dejetos-1, ja as maximas degradacoes de FDN ocorreram com adicoes de ate 69,4g de oleo de descarte kg dejetos-1. As inclusoes de ate 64g de oleo de descarte kg dejetos-1 possibilitaram producoes especificas de biogas de 291,4 e 251,0 L de biogas.kg SV-1 adicionado, para substratos contendo dejetos de suinos e bovinos respectivamente. A adicao de oleo em doses entre 45,1 e 69,4g.kg-1 a substratos contendo dejetos de bovinos ou suinos maximiza as reducoes dos constituintes solidos e fibrosos bem como potencializa as producoes especificas de biogas, sendo que o dejeto de suino ainda suporta maiores doses de inclusao de oleo residual. Palavras-chave: biodigestao; biogas; reciclagem energetica