Effect of substituting water source on the methane production from lignocellulosic biowaste during anaerobic digestion

Abstract

The escalating global volume of sewage discharge presents a formidable challenge for sewage treatment facilities, necessitating the efficient utilization of sewage. Given the substantial demand on water resource during anaerobic digestion (AD), this study investigated the feasibility of substituting pure water with sewage as the main water source for AD using six diverse lignocellulosic wastes (rice straw, vinegar residue, cattle manure, sheep manure, napkin, and office wastepaper) as feedstocks. The results showed that the methane production of lignocellulosic waste + raw wastewater (WW) during AD increased by at least 5% compared with the control groups. Specially, the cumulative methane yield of napkin mixed with the WW reached to 218.3 mL/gVS with the increase of 47.8% compared with the control group (147.7 mL/gVS). The results indicated that the relative abundance of characteristic bacteria and methanogenic archaea during AD was closely related to the kinds of feedstocks and water source. The addition of WW increased the relative abundance of bacteria and archaea in the digester, which might be the main reason for the higher methane production with the addition of WW. Treated wastewater and reclaimed water had a relatively neglectable impact on the microbial community structure in AD. This study not only saved water resources in AD but also provided a strong reference for resource utilization of sewage and organic solid waste.