碳酸氢盐碱度对低温厌氧消化及微生物群落的影响

Effects of Bicarbonate Alkalinity on the Characteristics of Anaerobic Digestion and Microbial Community at Low Temperature

15 ℃条件下,通过投加不同浓度碳酸氢钠来控制厌氧体系的碱度,采用间歇实验进行厌氧消化研究。结果显示,碳酸氢钠投加量为0.10 mol/L时,体系能维持厌氧微生物适宜生长的pH,48 h内化学需氧量(COD)去除率达到75.43%。继续增大投加量,COD去除率没有明显升高;随着碳酸氢盐碱度的增加,挥发性脂肪酸(VFA)浓度峰值升高,但积累的VFA降解速度减慢;高浓度的碳酸氢盐碱度可以缩短产甲烷的滞后时间,但最终累积甲烷产量受其影响较小;碳酸氢盐碱度的适量投加可促进低温厌氧消化过程中微生物的生长代谢,提高微生物群落的丰富度以及多样性。

The alkalinity of anaerobic system was controlled by adding different concentration of sodium bicarbonate at a low temperature (15 ℃). The intermittent batch experiments were implemented for the research. The results show that pH could be maintained at an appropriate value of anaerobic microorganism and the removal rate of chemical oxygen demand(COD) reached to 75.43% within 48 h when the dosage of sodium bicarbonate was 0.10 mol/L. The removal rate of COD did not increase significantly with the increase of dosage. The peak value of volatile fatty acids (VFA) concentration increased and the degradation rate of accumulated VFA slowed down as the initial concentration of bicarbonate alkalinity increased. The high concentration of bicarbonate could shorten the lag time of methane production, but the final cumulative methane production was less affected by the concentration of bicarbonate.The appropriate dosage of bicarbonate alkalinity promoted the growth and metabolism of microorganisms and improved the richness and diversity of microbial communities in the process of low temperature anaerobic digestion.