金属离子屏蔽腐殖酸对污泥厌氧消化抑制作用实验研究

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作为外加填充腐殖质,通过投加外源金属离子实验研究屏蔽腐殖质对污泥厌氧消化过程的抑制作用.结果表明,单独投加Ca2+与Al3+可分别获得65.4%和65.7%的屏蔽抑制率;Ca2++Al3+组合投加效果更佳,可获得高达80.1%的屏蔽抑制率,具有"1+12"的屏蔽抑制效果.然而,过高的金属离子含量(或组合含量)不仅无助于进一步提高屏蔽抑制效果,反而会因抑制微生物活性而导致屏蔽抑制率下降.Ca2+通过阳离子交换产生屏蔽抑制作用,而Al3+主要靠静电作用和网捕卷扫作用产生屏蔽效果.在屏蔽腐殖酸抑制方面,三价金属离子好于二价金属离子的原因是两者的静电作用力大小、作用方式、环境效果不尽相同.

Experimental study on shielding the inhibition effect of humic acid on anaerobic digestion of excess sludge by metals

Based on excess sludge cultured in laboratory with little humic substances and metals and by using merchandized humic acid which is similar to humic substance in municipal sludge in characteristics, shielding the inhibition of humic substances on the processes of anaerobic digestion of excess sludge was experimentally studied by dosing metals into the cultured sludge. Individually dosing Ca²⁺ or Al³⁺ could shield 65.4% and 65.7% on the inhibition ratio respectively; together dosing Ca²⁺+Al³⁺ made an even better the inhibition ratio, up to 80.1%, posing a shielding effect of "1+1>2" on the inhibition. However, over-dosing metals or their combination did not promote any higher shielding inhibition ratio; conversely, the shielding inhibition ratio get down due to inhibiting microorganisms'' activity. Ca²⁺ mainly mitigates the inhibition on hydrolysis by cation exchange with humic acid; Al³⁺ takes effect on the inhibition by electrostatic action and catching-sweeping. On shielding the inhibition of humic acid, trivalent metal is better than divalent metal due to different electrostatic actions, acting ways and environmental effects.