Effect of acid pre-treatment on the anaerobic co-digestion of physicochemical sludge, poultry manure and sugarcane wastes (SCW) for biogas production

Abstract

In Mexico, productive activities related to poultry farming and the sugarcane industry generate large amounts of three byproducts: physicochemical residual sludge, poultry manure, and sugarcane wastes, which have high concentrations of organic matter and lignocellulosic material. Therefore, the objective of the present study was to evaluate the effect of acid pre-treatment, with different doses of acetic acid (2%, 3%, and 4% v.v− 1) and exposure times of 30, 60, and 90 min on the solubilization of organic matter and biogas production in the anaerobic co-digestion of a mixture of agroindustrial wastes (residual sludge, chicken manure, and sugarcane wastes). The biodegradability and biogas production were evaluated by anaerobic digestion for 30 days. Finally, for 90 days semi-continuously, the increase in applied organic load of 1 kg VS m− 3 d− 1 was considered with Δ1 kg VS m− 3 d− 1 every 30 days until reaching 3 kg m− 3 d− 1. Acid pre-treatment with a dose of 4% acetic acid and an exposure time of 90 min improved the solubility and hydrolysis, considered the limiting stage of the anaerobic process, reducing the hydraulic retention time from 19 to 11 d, and increasing biogas yields (Ybio=609 ± 11.7 to 1857.2 ± 7.5 Lbio gVSrem−1) and methane (YCH4 = 426.9 ± 8.19 to 1392.9 ± 5.65 LCH4 gVSrem−1).