Mesophilic Anaerobic Study on Chinese Herbs Residues of Honeysuckle and Midday Tea

Abstract

A large number of Chinese herbs residues were produced during the production of honeysuckle and midday tea. Usually, the content of organic components in the residues was at a high level. These residues would pose a great threat to the local water environment, if they were not treated and disposed properly. In this paper, a self-prepared anaerobic reactor was utilized to treat the residues of honeysuckle and midday tea in semi-solid phase media. The anaerobic sludge was inoculated into the residues for anaerobic digestion at the temperature of 37±1°C, and ISRs (ISRs is the total solid mass ratio between inoculum and substrate) were 1:2, 1:1, 2:1 respectively. The result showed that the ultimate maximum yield of methane was the under ISRs of 1:1, the cumulative methane production volume of honeysuckle and midday tea dregs were 5832mL/100g and 5591mL/100g, respectively, after 192h digestion. Under the best inoculation ratio of 1:1, another mesophilic anaerobic experiment was carried out by mixing the residues of honeysuckle and midday tea as substrate at different ratios of 0:3, 1:2, 1:1, 2:1 and 3:0, respectively, which were to compare the methane production at 37±1°C. The result indicated that the ultimate maximum yield of methane was under mixed ratio of 1:2, the cumulative methane production volume of the mixed Chinese herbs residues was 9110 mL/100g after 192h digestion. Furthermore, the zero-order kinetic model was found to be suitable to characterize the removal ratio of substrate during 0~108h digestion while the biogas was generated fast, and the kinetic constant k was 50.49mL/h. To obtain the ultimate maximum rate of methane production, the anaerobic reaction should be controlled under the stage of zero-order reaction. Thus, the experimental results could provide scientific proof for anaerobic treatment and methane recycling in organic waste of Chinese herbs enterprises.