Biochemical methane potential experiments were conducted to investigate the effects of organic loading rate on the performance of anaerobic digesters with vinegar residues. According to the comparisons of methane production and liquid phase compositions, as well as thermogravimetry, X-ray Diffraction and infrared spectroscopy analyses, the conclusions could be drawn that:①Lower organic loading rate was better to mitigate the accumulation of VFAs and pH decrease during the hydrolysis and acidification of organic matters, which consequently improved methane production. When the inoculum to substrate ratio was 1:1[organic loading rate of 1.78 g·(L·d)-1, pH=7.60], the cumulative methane production was the highest, reaching 2249.7 mL, and the performance of the digesters was stable. The VFAs content increased with the increase of the organic loading rate, leading to the suppression and further the stop of methane production. And when the inoculum to substrate ratio was 1:4[organic loading rate of 7.12 g·(L·d)-1, pH=5.52], the simultaneous generation of acetate and lactic acids could be achieved at 8000 mg·L-1 and 2650 mg·L-1, respectively. ② As vinegar residues were short-range ordered with microcrystalline structure or mainly contained amorphous substances, they were more biodegradable than feedstocks such as corn stalk. During the anaerobic digestion processes, the degradation rates of lignin, cellulose and hemicellulose increased with the decrease of organic loading rate.
Keywords: anaerobic digestion; infrared spectroscopy; organic loading rate; thermogravimetry; vinegar residues.