RSI-MO反应器强化沼气原位深度脱硫研究

为实现剩余污泥厌氧消化沼气原位深度脱硫,采用向反应器中嵌入最佳剂量(20g/L)废铁屑并引入微氧条件,构建废铁屑-微氧(RSI-MO)工艺,探索微氧效应对厌氧消化稳定性、效率、脱硫的影响.试验分7阶段,P1阶段对照组,P2阶段加入RSI,P3~P7阶段逐步提高O₂剂量. 结果表明,MO激发硫氧化菌生物脱硫,促发RSI化学腐蚀而生成铁硫沉淀物,耦合生物脱硫与化学除硫作用.P3~P7阶段,随O₂剂量的提高,H₂S浓度呈降低趋势,而残余O₂浓度呈升高趋势.综合来看,P6阶段反应器厌氧消化效率和脱硫效率最佳,甲烷产率达301.1mL/gCOD、沼气H₂S浓度为113mg/m³,较P1阶段分别提高37.65%和99.40%.通过硫平衡分析发现,P6阶段存在于固、液、气三相硫元素含量分别占84.0%、11.9%、0.21%.表明RSI-MO工艺可实现沼气原位深度脱硫.

Study of combining rusty scrap iron with micro-oxygen to enhance biogas in-situ deep desulfurization

To achieve biogas in-situ deep desulfurization of waste-activated sludge (WAS) anaerobic digestion. An integrated rusty scrap iron-micro-oxygen (RSI-MO) anaerobic digestion process was constructed embedding optimal RSI dosage (20g/L) and providing micro-oxygen condition to explore the influence of RSI-MO process on anaerobic digestion in-situ desulfurization performance. This semi-continuous anaerobic/microaerobic experiment was carried out in seven stages (P1~P7). The first stage (P1) was set as a control group. RSI was added in the second stage (P2). And increasing O₂ levels were introduced stepwise in P3~P7stages. The results showed that supplementary O₂ induced sulfur-oxidizing bacteria microbial oxidation of sulfide to elemental sulfur and chemical oxidative corrosion of iron to form ironic sulfide precipitate. It promoted the sulfide solidification by coupling of biological desulfurization with chemical desulfurization. From P3 to P7, the content of H₂S in biogas decreased and residual oxygen increased with rising of O₂ dose, respectively. The optimum performance was considered on the basis of anaerobic digestion efficiency and desulfurization property, which was obtained in P6. The methane yield was 301.1mL/gCOD, and the H₂S concentration was 113mg/m³. The average methane yield increased by 37.65% comparing with P1. What’s more, the H₂S removal efficiency in biogas decreased by 99.40%. According to the analysis of sulfur balance, it was found that the sulfur contents in solid-liquid-gas three phases accounted for 84.0, 11.9 and 0.21 percent of total sulfur in P6, respectively. It is indicated that the integrated process of RSI-MO anaerobic digestion could benefit biogas in-situ deep desulfurization.