Influence Factors And Mechanismresearch About Food Waste Anaerobic Digestion For Methane Production

Anaerobic digestion is a way to dispose food waste, it not only a method for food waste reduction, avoid food waste to decay, stink and be used by traffickers, at the same time it can conver food waste into clean energy--methane.However, in our country the food waste anaerobic digestion is still in the laboratory research stage at present, industrial application is less. This is mainly as many influence factors in anaerobic digestion process, one factor lose control would lead to failure of reaction and serious economic losses.This study explores four mainly influence factors during food waste anaerobic digestion for methane production, including salt, long chain fatty acid, ammonia nitrogen and organic load rate.This study shows that:1) Exploring the influence of sodium salt on anaerobic digestion by change the concentration of NaCl. At mesophilic, the addition of NaCl less than 3 g/L could promote biogas production. At thermophilic, the highest gas production was in not adding NaCl reaction. Although high sodium concentration inhibited the methane gas production at mesophilic and thermophilic, the percentage of methane could be improved to a certain extent.2) In the study of long chain fatty acid, the actual methane production in no long chain fatty acid added reaction was closest to the theoretical value, the results showed that although the long chain fatty acids can be utilized by microorganisms to produce methane, the process was relatively slow and the reaction was not complete.3) In the study of organic load rate, anaerobic digestion could run stable when organic load rate less than 1.5 g-VS/L at mesophilic, the best loading ande methane production rate were 1 g/L and 387 mL/g-VS and methane content was about 50%. At thermophilic, organic load rate less than less than 2.5 g-VS/L anaerobic digestion kept stable operation,|the best loading and methane production rate were 1.5 g/L and 551 mL/g-VS.4) In ammonic impact experiment, inhibition effects were observed when the total ammonia concentration was above 2 g/L. The inhibition was mainly effected on the methanogenesis process, while the hydrolysis and acidification processes were less affected. The ammonia inhibition on methane fermentation would further led to accumulation of acetate and propionate and drop of pH value, which worsened the inhibition effects. As the ammonia concentration increased, the methane generation pathway shifted from strict aceticlastic methanogenesis to more complex and flexible pathways significantly enriched the SAO-HM pathway. And microorganisms irrelevant with the methane fermentation process were also enrichhed.