Batch and continuous anaerobic digestion of different organic waste streams 机翻标题: 暂无翻译,请尝试点击翻译按钮。

Chen, Xiguang;
In this study, batch digestion tests were carried out to treat five different food wastes, grease trap waste, glycerin, the co-digestion of five food wastes, the co-digestion of grease trap waste and dairy manure, and the co-digestion of glycerin and dairy manure. The batch reactor used in this study had total and working volumes of 1130 mL and 500 mL, respectively. The initial organic loading was set to be 3.0 g VS/L and the food to microorganism ratio was either 0.5 or 1.0 for different treatments based on the characteristics of each waste stream. Both mesophilic (35 ± 2°C) and thermophilic (50 ± 2°C) temperatures were tested for the five food waste streams whereas only the mesophilic condition was applied to grease trap waste and glycerin due to their fast hydrolysis products would drop the pH and inhibit the methanogens especially under thermophilic conditions. All the batch digestion tests were successful in terms of biogas yield, biogas production rate and solid reductions. The results from batch anaerobic digestion tests were then used for designing continuous digestion experiments. All the continuous digestion experiments were conducted by using a continuous bioreactor mixed by biogas circulation system located in an environmental chamber at mesophilic temperature. The total and working volumes of the continuous bioreactor were 20 L and 18 L, respectively. The hydraulic retention time (HRT) was 20 days and the organic loading rate (OLR) started from 0.5 g VS/L/d and increased stepwise once the digestion system reached quasi-equilibrium as determined by steady gas production. The results from the continuous digestion tests indicated that the microorganism in the co-digestion of food wastes were inhibited by the accumulation of volatile fatty acids due to highly biodegradable carbon content in food wastes. Addition of alkali such as sodium hydroxide was required for pH adjustment and alkalinity control. The biogas yields at OLR of 0.5 and 1.0 g VS/L/d were 0.16 ± 0.02 and 0.27 ± 0.01 L/g VS, respectively. By contrast, co-digestion of dairy manure with waste having highly degradable carbon content, grease trap waste and glycerin in this case was feasible due to the buffering capacity of dairy manure. The biogas yields from co-digestion of grease trap waste and dairy manure at OLR of 0.5, 1.0, and 2.0 g VS/L/d were 0.27 ± 0.02, 0.27 ± 0.01 and 0.25 ± 0.03 L/g VS, respectively. The biogas yield from co-digestion of glycerin and dairy manure at OLR of 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g VS/L/d were 0.47 ± 0.03, 0.57 ± 0.05, 0.57 ± 0.14, 0.55 ± 0.20, 0.54 ± 0.14 and 0.61 ± 0.18 L/g VS, respectively. Co-digestion of either grease trap waste or glycerin with dairy manure is highly feasible, and can significantly improve the biogas production efficiency. (Abstract shortened by UMI.)
Microbiology;Environmental engineering;Energy
University of California, Davis
MicrobiologyEnvironmental engineeringEnergy
Zhang, Ruihong