Statistical Modeling of the Methane Production from Slaughterhouse Wastes in Anaerobic Co-digestion

A simplex-lattice mixture design and the surface response methodology (SRM) were used to modeling the methane production on the anaerobic co-digestion (AcoD) of three different substrates generated from slaughterhouses: manures (Ms), solid organic wastes (SOW) and wastewaters (SHWW). In the first stage of the study, a characterization of these residuals was carried out; meanwhile, the mixture design was used in the second step to determine the methane production obtained on the AcoD of the substrates considered. The results of the analysis of RSM show that the best adjusted model was the special cubic, with high values of R2 and R2adj of 95.13% and 90.96%, respectively. According to the statistical – mathematical model obtained in this study, wastes generated from slaughterhouses are appropriated material for acquire biogas; nonetheless, significant antagonistic effects was observed when increasing the amounts of SOW and SHWW, apparently by the increase in the levels of proteins and fat, oil and grease (FOGs). A good strategy to implement in order to achieve high methane productions for the effluent treatments from meat producing industries is a combination of substrates Ms and SOW; meanwhile, is preferable to separately treat the SHWW in high rate AD systems or anaerobic lagoons.