Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China.
Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou 730000, Gansu, China; Department of Biosciences, COMSATS University Islamabad, Pakistan.
J Environ Manage. 2019 Jun 15;240:266-272. doi: 10.1016/j.jenvman.2019.03.104. Epub 2019 Apr 2.
Heavy metals (HMs), which accumulate in digestion substrates, such as plant residues and livestock manure, can affect biogas yields during anaerobic digestion (AD). Low concentration of Cu (0-100 mg/L), Fe (50-4000 mg/L), Ni (0.8-50 mg/L), Cd (0.1-0.3 mg/L), and Zn (0-5 mg/kg) promote biogas production, while high concentrations inhibit AD. Trace amounts of HMs are necessary for the activity of some enzymes. For example, Cu and Cd serve as cofactors in the catalytic center of cellulase and stimulate enzyme activity. High contents of Cd and Cu inhibit enzyme activity by disrupting protein structures. Trace amounts of HMs stimulate the growth and activity of methanogens, while high levels have toxic effects on methanogens. HMs affect the hydrolysis, acidification, and other biochemical reactions of organics in AD by changing the enzyme structure and they also impact methanogen growth. A better understanding of the impact of HMs on AD can provide valuable insights for improving the digestion of poultry manure and plant residues contaminated with HMs, as well as help mitigate HMs pollution. Although several studies have been conducted in this field, few comprehensive reviews have examined the effect of many common HMs on AD. This review summarizes the effects of HMs on the biogas production efficiency of AD and also discusses the effects of HMs on the activities of enzymes and microbial communities.
重金属（HMs）会在消化底物（如植物残渣和牲畜粪便）中积累，从而影响厌氧消化（AD）过程中的沼气产量。低浓度的 Cu（0-100mg/L）、Fe（50-4000mg/L）、Ni（0.8-50mg/L）、Cd（0.1-0.3mg/L）和 Zn（0-5mg/kg）可以促进沼气的产生，而高浓度则会抑制 AD。痕量的 HMs 是某些酶活性所必需的。例如，Cu 和 Cd 作为纤维素酶催化中心的辅助因子，刺激酶的活性。Cd 和 Cu 的高含量通过破坏蛋白质结构来抑制酶的活性。痕量的 HMs 可以刺激产甲烷菌的生长和活性，而高浓度则对产甲烷菌有毒。HMs 通过改变酶的结构，影响 AD 中有机物的水解、酸化和其他生化反应，也会影响产甲烷菌的生长。更好地了解 HMs 对 AD 的影响，可以为提高受 HMs 污染的家禽粪便和植物残渣的消化效率提供有价值的见解，并有助于减轻 HMs 污染。尽管在这一领域已经开展了几项研究，但很少有全面的综述研究考察了许多常见 HMs 对 AD 的影响。本综述总结了 HMs 对 AD 沼气产量效率的影响，还讨论了 HMs 对酶和微生物群落活性的影响。
