Experimental and kinetic study on anaerobic digestion of food waste: The effect of total solids and pH

This paper aims at finding the effect of co-digestion of cow dung and food waste on total biogas yield. Biogas production was improved through co-digestion of cow dung and food waste (FW) containing a small fraction of inoculum under mesophilic temperature (37ºC) over a retention time of 24 days. Co-digestion ratios of 1:1, 2:1 and 3:1 for cowdung/foodwaste were used for the study on anaerobic digestion on the co digested matter. Tests were carried out starting with the preparation of substrates, substrate characterization to determine the moisture content (MC), total solids (TS), volatile solids (VS) and ultimately batch anaerobic digestion experiments under thermophilic conditions (370C). The moisture content, volatile solids and total solids for food waste were 78, 22 and 90.7% respectively while the characteristics for cow dung were 67.2, 32.8 and 96.0 % respectively. From the study, a mixing ratio of cow dung: food waste of 1:2 was found to be the optimum substrate mixture for biogas production at 25595.7 Nml. The accumulated gas volumes of 18756.6, 14042.5, 13940.8 and 13839.1 Nml were recorded for cow dung: food waste ratios of 2:1, 1:1, 1:3 and 3:1 respectively. For a co-digestion containing more of the food waste than cow dung, a higher volume of biogas is produce.

Download Full-text

Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

Biological Treatment of Solid Waste ◽

10.1201/b18872-8 ◽

2015 ◽

pp. 49-72

Keyword(s):

Anaerobic Digestion ◽

Food Waste ◽

Total Solids ◽

Microbial Characteristics ◽

Characteristics Analysis ◽

Mesophilic Conditions

Download Full-text

Effect of total solids contents on the performance of anaerobic digester treating food waste and kinetics evaluation

E3S Web of Conferences ◽

10.1051/e3sconf/202127201026 ◽

2021 ◽

Vol 272 ◽

pp. 01026

Author(s):

Xiao-Fei Zhao ◽

Yan-Qi Yuan ◽

Qing-Kong Chen ◽

Qi Li ◽

Yan Huang ◽

...

Keyword(s):

Anaerobic Digestion ◽

Food Waste ◽

Methane Production ◽

System Stability ◽

Hydrolysis Rate ◽

Batch Reactors ◽

Total Solids ◽

Rate Of Hydrolysis ◽

New Perspective ◽

Production Dynamics

The effects of total solids (TS) content on the performance of anaerobic digestion (AD) treating food waste (FW) and kinetic characteristics were investigated in mesophilic batch reactors. The results showed that FW could be digested normally in the AD system within the TS of 3%-30%. The volume methane yield of dry-AD increased by 5.2-10.6 times than that of wet-AD and the degradation time of unit substrate was shortened by 35%-71%. The system stability indicators of dry-AD, such as pH, VFA/TA, TAN and salt remain within the suppression threshold after digestion. dry-AD had obvious advantages. The kinetic analysis showed that ADM1 could be used to simulate the anaerobic digestion reactor of FW, and accurately simulated the methane production in different TS systems after calibrating. With the increase of TS, the hydrolysis and methane production showed a tendency to increase first and then decrease, but the decrease rate of hydrolysis was higher than that of methanogene. Increasing TS simultaneously weaken the hydrolysis rate and methanation rate, but the effect on the hydrolysis and acidification phase weaker. The ratio of the hydrolysis rate constant to the methanogenic Monod maximum specific absorption rate (khy/km_ac) was a new perspective to used to evaluate the balance between the hydrolysis stage and the methane production stage. The results show that the khy/km_ac ratio of the 15% TS and 20% TS experimental groups was close to 1. It can be speculated that the system TS between 15%-20% can be used as recommended value in anaerobic digestion engineering design to treat FW. Within this TS range, hydrolysis and methane production dynamics matching, the accumulation of inhibitors is also in a relatively moderate state in the threshold.

Download Full-text