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(558bd) Biochar As an Effective Additive to Enhance Anaerobic Digestion of Easily Acidified Food Waste

Zhou, H., Iowa State University
Brown, R. C., Iowa State University
Wen, Z., Iowa State University
Food waste (FW), accounting for more than 1/3 of the municipal solid waste, is increasing due to economic and population growth. Anaerobic digestion (AD) is a widely used technology to degrade food waste to generate biogas as energy while addressing waste management and nutrient recycling. However, due to high amount of easily biodegradable compounds in FW, AD always suffers instability and low reactor efficiency. Rapid accumulation of volatile fatty acids in the process would subsequently result in lower pH (known as acidification) and inhibit methanogenesis.

Biochar derived from biomass fast pyrolysis has been increasingly studied as additive in AD, since it shows various benefits. Biochar can provide buffering capacity to prevent the quick pH dropping in the digester. As a porous carbonaceous material, biochar facilitates the direct interspecies electron transfer between bacteria and methanogenic archaea. Moreover, it can shorten the lag phase and enhance methane production in AD. In this work, we aim to study the effect of biochar addition on AD of easily acidified FW. The biochar was derived from fast pyrolysis of corn stover at 550 ℃. With 4% biochar addition, the biogas production and methane production were increased by 31.1% and 18.9% compared to the control without biochar addition, respectively. The pH dropping was slowed down by addition of biochar as well. Further study comparing a stepwise addition and pulse addition of biochar in digester will be carried out to further enhance methane production and sequester CO2 from AD of FW.