乙醇发酵预处理耦合生物炭强化城镇有机固废厌氧产甲烷

Enhancing methane production during anaerobic digestion of municipal organic solid wastes by ethanol-type fermentation pretreatmentcoupled with biochar addition

当前厌氧消化的核心技术原理是种间氢传递(IHT),其对扩散传质依赖高,在处理城镇有机固废(MOSW,主要包括餐厨垃圾和剩余污泥)时易受阻,导致厌氧产甲烷停滞。直接种间电子传递(DIET)对扩散传质依赖低,可取代IHT,成为城镇有机固废厌氧产甲烷的主要工作模式。乙醇型发酵预处理和投加碳基导电材料是促进厌氧消化中DIET的两大手段。以实际城镇有机固废为底物,采用乙醇型发酵预处理耦合生物炭的方法,对强化厌氧产甲烷性能进行探究。结果显示:(1)通过优化酿酒酵母培养时间、接种比及培养基组成,获得了酿酒酵母的最佳培养条件(培养时间为21.17 h,接种比为15%,每30 mL液体培养基组成为3.00 g葡萄糖、0.12 g蛋白胨、0.12 g酵母浸出粉及微量元素);(2)通过优化乙醇型发酵预处理的温度和酿酒酵母的接种比,获得了乙醇型发酵预处理的最佳工艺条件(最佳发酵温度为37℃,酿酒酵母接种比为20 mL/L);(3)设计半连续流厌氧消化实验,探究乙醇型发酵预处理耦合生物炭对城镇有机固废甲烷产量和底物去除的影响。相比于对照组,乙醇型发酵预处理(接种20 mL/L酿酒酵母)耦合生物炭(2 g/L)组的甲烷产量提高了102.50%,底物去除率提高了16.15%;(4)微生物群落分析发现,乙醇型发酵预处理耦合生物炭提高了Methanosaeta的相对丰度。优化了酿酒酵母的培养条件,确定了乙醇型发酵预处理的最佳温度和接种比,降低了经济成本。通过乙醇型发酵预处理耦合生物炭,构建了厌氧消化中DIET,强化了厌氧产甲烷,提高了城镇有机固废的资源化和减量化。

Nowadays,the main mechanism of traditional anaerobic digestion relies on interspecific hydrogen transfer(IHT).However,IHT is highly dependent on mass transfer and diffusion rates,which can be hindered during the treatment of municipal organic solid wastes(MOSW),mainly including food waste and waste activated sludge.This hindrance leads to stagnation of methane production.Direct interspecific electron transfer(DIET)has a low dependence on these rates,making it a promising alternative to IHT for methane production in MOSW anaerobic digestion.Currently,ethanol-type fermentation pretreatment and the addition of carbon-based conductive materials are used to promote DIET.In this study,we used municipal organic solid wastes as the substrate to explore the enhancement of anaerobic methane production performance through ethanol-type fermentation pretreatment coupled with biochar addition.The results showed that:(1)Optimal cultivation conditions were achieved for brewing yeast by optimizing the cultivation time,inoculation ratio,and medium composition.The optimal conditions were as follows:cultivation time of 21.17 hours,inoculation ratio of 15%,and medium composition per 30 mL liquid medium of 3.00 g glucose,0.12 g peptone,0.12 g yeast extract powder,and trace elements.(2)The best process conditions for ethanol-type fermentation pretreatment were determined by optimizing the temperature and inoculation ratio of brewing yeast.The optimal conditions for ethanol-type fermentation were at temperature of 37℃and a brewing yeast inoculation ratio of 20 mL/L.(3)A semi-continuous flow anaerobic digestion experiment was designed to investigate the effect of ethanol-type fermentation pretreatment coupled with biochar on methane production and substrate removal of MOSW.Compared to the control group,the ethanol-type fermentation pretreatment(inoculated with 20 mL/L brewing yeast)coupled with biochar(2 g/L)group increased methane production by 102.5%and substrate removal rate by 16.2%.(4)Microbial community analysis revealed that ethanol fermentation pretreatment coupled with biochar increased the relative abundance of Metanosaeta.This study optimized the culture conditions of yeast and determined the optimal pretreatment temperature and inoculation ratio of ethanol fermentation to reduce economic costs.By employing ethanol-type fermentation pretreatment coupled with biochar addition,DIET was established to enhance methane production and improve the resource utilization and reduction during MOSW anaerobic digestion.