Optimized production conditions and activation of biochar for effective promotion of long-chain fatty acid degradation in anaerobic digestion

Abstract

Engineered biochar production and utilization in anaerobic digestion (AD) potentially overcome its limited application to the treatment of slowly degradable or inhibitory substrates. Here an attempt was made to develop an optimized biochar production procedure for use in AD to stimulate palmitic acid biodegradation via direct interspecies electron transfer (DIET). The electrical conductivity of biochar was greatly increased with an elevated pyrolysis temperature and K2CO3 activation, and the conductivity reached a comparable level (0.6–1.4 S/cm) to that of carbon black at 800 °C. In addition, the K2CO3 activation greatly improved biochar wettability. When using K2CO3-activated biochar produced at 800 °C, the maximum methane production rate from palmitic acid was 1.3 times that of a control without biochar addition.