零价铁对厌氧消化过程中氨氮抑制解除的影响

氨氮抑制是影响高含固有机固体废弃物厌氧消化产甲烷效率的重要因素.本研究通过实验室批量实验,考察了微米级零价铁对剩余污泥、热水解污泥厌氧消化的影响以及对高氨氮抑制解除的影响.结果表明,投加4 g·L~(-1)和10 g·L~(-1)零价铁对剩余污泥、热水解污泥厌氧消化过程中的产甲烷速率、迟滞时间和产甲烷潜势等动力学特征均未有影响.但是,在高氨氮抑制的厌氧消化过程中, 4 g·L~(-1)和10 g·L~(-1)的零价铁投加可使厌氧消化受氨氮抑制的产甲烷迟滞时间由对照组的18.61 d分别缩短为17.22 d和16.18 d,最大产甲烷速率(以VS计)由对照组的6.34 mL·(d·g)~(-1)提升为7.84 mL·(d·g)~(-1)和7.39 mL·(d·g)~(-1).零价铁并未通过化学反应对厌氧消化的pH缓冲体系产生直接影响,而是使氨氮抑制后的产甲烷优势古菌Methanosarcina的相对丰度(27 d)由对照组的30.71%提升到53.50%和60.30%.本研究证明了零价铁并不能提升污泥产甲烷潜势,而只是在受抑制影响的厌氧消化过程中,刺激产甲烷微生物的代谢活性,强化如氨氮抑制影响的快速解除.

Effect on Ammonia Inhibition Mitigation in the Anaerobic Digestion Process with Zero-Valent Iron

Ammonia inhibition is an important factor impacting methane production efficiency during the anaerobic digestion of high-solid organic wastes. This study investigated the effect of micro-sized zero-valent iron (m-ZVI) on the anaerobic digestion of excess sewage sludge and thermal hydrolyzed sludge using batch mode experiments. The effect of m-ZVI on ammonia inhibition mitigation was also studied. Results showed that the kinetic characteristics of the methane production rate, lag phase, and methane production potential of the anaerobic digestion of excess sludge and thermal hydrolyzed sludge were not impacted by the addition of m-ZVI at a dosage of 4 g·L^-1 and 10 g·L^-1. However, during the inhibited anaerobic digestion process with a high ammonia concentration, the addition of 4 g·L^-1 and 10 g·L^-1 of m-ZVI was able to shorten the lag phase from 18.61 d (the control) to 17.22 d and 16.18 d, respectively. Moreover, the maximum methane production rate (based on the VS) increased from 6.34 mL·(d·g)^-1(the control) to 7.84 mL·(d·g)^-1 (4 g·L^-1 m-ZVI) and 7.39 mL·(d·g)^-1 (10 g·L^-1 m-ZVI). The pH buffer system was not influenced by the chemical reaction of m-ZVI in the anaerobic digestion, although the relative abundance of the dominant methanogenic archaea (Methanosarcina) improved greatly from 30.71% (the control) to 53.50% (4 g·L^-1 m-ZVI) and 60.30% (10 g·L^-1 m-ZVI) at 27 d. This study proved that m-ZVI was incapable of improving the methane production potential of sewage sludge, while the mitigation of ammonia inhibition during anaerobic digestion was enhanced by the stimulating effect on methanogenic archaea.