Effects of different low temperature conditions on anaerobic digestion efficiency of pig manure and composition of archaea community

Abstract

To explore the effect of low temperature on the anaerobic digestion of pig manure, the anaerobic digestion experiment was carried out under the conditions of inoculum concentration of 30% and TS of 8%. Five low-temperature gradients of 4, 8, 12, 16 and 20 °C were set to study the activities of gas production, pH, SCOD (Solluted Chemical Oxigen Demand), VFAs (Volatile Fatty Acids), coenzymes F420 and archaea community composition in the digestion process. The results were demonstrated: as the temperature decreased, the more unstable the gas production became, the less gas production produced, and the later the gas peak occurred. There were no significant peaks at either 4 °C or 8 °C, and the SCOD was unstable over time. From 12 °C, the SCOD increased over time, and the higher the temperature, the faster the growth trend. The pH was always greater than 7.6. 8, 12, 16, 20 °C had different degrees of VFAs accumulation at the late digestion stage. The higher the temperature, the greater the amount of volatile acid accumulation. When the VFAs of each reactor reached the maximum, the proportion of acetic acid also reached the highest. The digestion system of the five treatment groups was dominated by hydrogen-nutrient methanogenic pathway. The results could provide a further reference for the mechanism of anaerobic digestion of pig manure at low temperatures.

Effect of nano-Al2O3 and multi-walled carbon nanotubes on the anaerobic mono-digestion of sludge and the co-digestion of tobacco waste and sludge

“…The accumulation of VFAs can lead to the reduction of biogas production. 38 In the middle stages of AD (from day 15 to day 21), the VFA concentration was signicantly lower in the CTA reactor. Trophic methane bacteria acetate can join in the intermediate transfer of acetic acid.…”

Effect of Temperature on Co-Anaerobic Digestion of Chicken Manure and Empty Fruit Bunch: A Kinetic Parametric Study

“…The significantly higher B o and R b is further testimony that MAD is more apt compared to PAD and TAD in the case of chicken manure and EFB acting as co-substrates in a single system. EFB being rich in cellulose, hemicellulose and lignin strains microbial degradation [23] posing a hurdle for PAD in addition to its instable nature [40]. On the other hand, TAD with chicken manure as the sole feedstock is highly prone to be subjected to ammonia toxicity as reported in a past study by Ao, et al [41].…”