Employing micro-aeration in anaerobic digestion of poultry litter and wheat straw: Batch kinetics and continuous performance

Abstract

In this study, different micro-aeration (MA) strategies for anaerobic digestion (AD) of poultry litter (PL) and wheat straw (WS) were examined. MA at different stages (pretreatment, middle, pretreatment plus middle, and daily) in batch AD of WS showed that daily MA had the highest increase (16.5 %) of the cumulative methane yield (CMY) compared to the control. Batch co-digestion (Co-AD) of WS and PL with daily MA obtained a furtherly improved (15.1 %) CMY of 225.44 N mL CH₄/g vS _added. The modified Gompertz model and Cone model were good in fitting the methane yield kinetics of MA engaged AD process (R² greater than 0.99). Daily MA shortened the lag phase of Co-AD by 3.4 %. The sequencing batch reactor for the Co-AD of WS and PL showed an increased (21.5 %) daily methane yield when 0.5-h/d MA was employed. The results provided support for the application of micro-aeration in the AD of agricultural wastes.

Keywords: Co-digestion; Daily methane yield; Kinetic model; Micro-aeration strategy; Sequencing batch reactor.