This study investigated the effects
of granular activated carbon
(GAC) dosing on the co-anaerobic digestion of municipal sludge and
food waste. It was found that methane production increased in the
GAC systems. The cumulative methane production in the 1 g·L–1 GAC system was 12.14% higher than the control. The
1 g·L–1 GAC system started very quickly at
the initial stage of anaerobic digestion (AD) and reached the highest
methane production per day on the 3rd day, while the control appeared
on the 10th day. The maximum methane production per day of the 1 g·L–1 experimental group was 12.27% higher than that of
the control. The pH of the 1 g·L–1 experimental
group varied less during the entire AD cycle. The reduction in sCOD,
TS, and VS of the 1 g·L–1 GAC system were 48.95,
23.26, and 10.20% higher than the control, respectively. The dominant
bacteria in the GAC systems were Thermotogae, Firmicutes, and Bacteroidetes,
and these bacteria play very important roles in the hydrolysis and
acidification stages. The main methanogen genus in the control was Methanosarcina, and those in the experimental systems were Methanobacterium and Methanolinea (which
are hydrogenotrophic methanogenic archaea). These
results indicate that the addition of GAC can relieve the acidification,
reduce the AD start-up time, and promote the activities and growth
of microorganisms to improve methane production by enhancing direct
interspecific electron transfer and interspecies hydrogen transfer.