微量金属元素及其螯合剂对厌氧消化产甲烷过程的影响

Effects of trace metal and its chelating agent on anaerobic digestion

高氨氮是厌氧消化系统中需要解决的关键抑制因素之一,在探讨氨氮对厌氧消化产甲烷影响的基础上,研究微量金属元素A和螯合剂B对高氨氮下厌氧微生物产甲烷活性的影响。结果表明,氨氮对厌氧消化产甲烷的临界抑制质量浓度为2.0g/L。适量的微量金属元素A和螯合剂B可促进厌氧消化产甲烷,当金属元素A的添加量为50 mg/L、螯合剂B添加量为10 μml/L及氨氮质量浓度为0.4g/L时,累积甲烷产量提高了 47.7%。

This paper is inclined to introduce our study over the effect of high-strength ammonium nitrogen on the anaerobic digestion. As is known, ammonium nitrogen is one of the key inhibitors to anaerobic digestion, an important problem to be resolved. Based on our investigation of the problem, we have evaluated the effect of trace metal ion A and its chelating agent B on methane production and found that 0.4 g/L ammonium nitrogen tends to promote the methnogenesis with no need to add the ammonium nitrogen. The inhibiting concentration of the ammonium nitrogen has also been obtained to be 2.0 g/L with the decrease of accumulated methane amount by 15.5 %. If the increase goes on, the accumulated methane amount is likely to decrease continuously. Proper addition of trace metal A and its chelating agent B has also been found to promote the anaerobic digestion. Moreover, in the condition when the concentration of metal A was 200μmol/L and 2 000 μmol/L, the inhibition of ammonium nitrogen is likely to get weakened or even eliminated with the methane amount generated increased by 38.7% and 63.4% as compared with the control. However, if the trace metal A＇ s concentration continuously increases, the accumulated methane amount would decrease. That can be accounted for the inhibition of trace metal A to the macromolecules, for example, RNA or protein. However, the superfluous dosage tends to decrease the methane amount, because under 0.0 g/L and 0.4 g/L of ammonium nitrogen, chelating agent B has also been found to be able to promote methane amount increase with the accumulated volume increased by 29.2% and 47.4%. But the ammonium nitrogen of 2.0%, 5.0% and 10.0% was also found to inhibit methanogenesis, for addition of chelating agent B proves to result in increase of free NH3 concentration. In case of trace metal A being 50 mg/L, chelating agent B of 10 μmol/L and ammonium concentration of 0.4 g/L, the accumulated methane amount would also increase by 47.7% as compared with the control. Thus, it can be concluded that the dosage of trace metal A and its chelating agent B helps 2 mmoL/L to increase in methane production.