腐殖酸影响剩余污泥厌氧消化过程实验研究

以实验室培养、几乎不含腐殖质和金属离子的剩余污泥作为研究对象,选择与市政污泥中腐殖酸特征相近的市售腐殖酸为外加填充物,实验研究污泥中所含腐殖质对污泥厌氧消化过程的抑制作用.通过设置腐殖酸不同投加比例(0、5%、10%、15%和20%,以VSS计),探究腐殖酸对厌氧消化不同过程的影响.实验结果表明,腐殖酸抑制厌氧消化生物气产气量.填加15%腐殖酸时对厌氧消化产气量抑制作用最为明显,较未添加腐殖酸对照组产气量下降了35%;但并未对生物气中CH_4体积比产生太大影响,说明抑制影响是对生物气整体性的.腐殖酸亦可抑制厌氧水解过程,投加20%腐殖酸实验组实验结束时残留于上清液中的溶解性多糖、蛋白质浓度分别是对照组的2.2和1.6倍.然而,腐殖酸作为外源电子受体,可以在一定程度上促进酸化过程,其程度在填加20%腐殖酸实验组表现最高,较对照组VFAs提高了11.3%.腐殖酸投加未对系统pH产生明显影响,各实验组pH值均在7.09~7.54间变化.

Experimental study on the effect of humic acid on the process of anaerobic digestion of excess sludge

Based on excess sludge cultured in laboratory with little humic substances and metals, merchandized humic acid which is similar to humic acid in municipal sludge in characteristics was selected to ascertain the impacting processes on anaerobic digestion of excess sludge. By setting the different dosing ratios of humic acid in the sludge (0, 5%, 10%, 15% and 20%, based on VSS), the experiments were used to explore the effects of humic acid on the different processes of anaerobic digestion. The experimental results indicate that humic acid inhibited biogas production. Dosing 15% of humic acid in the sludge resulted in the most serious inhibition on biogas, with the 35% decrease in biogas production compared to the control experiment without dosing humic acid; the decrease of biogas production did not change the CH₄ volume ratio in biogas, which reveals that the inhibition on biogas was comprehensive. Humic acid also inhibited the hydrolysis process of anaerobic digestion; residual soluble polysaccharides and protein in supernatant with dosing 20% of humic acid were respectively 2.2 and 1.6 times higher than the control experiment. However, humic acid could slightly promote the acidification process, behaving the highest increase (11.3%) on VFAs in the experiment with dosing 20% of humic acid. Dosing humic acid did not significantly affect pH in the experimental system, all in the range of 7.09~7.54.