生物炭对污泥热解液与牛粪共厌氧发酵的影响

Biochars enhancing anaerobic co-digestion of sewage sludge pyrolysis liquid and cow dung: influences of inorganics in biochar raw materials

利用4种以芦苇和互花米草为原料的生物炭促进含大量毒性有机物的污泥热解液(SSPL)和牛粪的共厌氧发酵,以实现SSPL的降解并促进其产甲烷,同时分析了炭源中无机质的影响.结果表明:与对照组相比,添加生物炭后可将产甲烷高峰日提前4~8d,累计甲烷产量提升78.8%~157.2%;4种生物炭的促进效果与其炭源中无机质的含量呈负相关.生物炭通过吸附SSPL降低其生物有效性、为微生物提供载体和微量元素、促进种间电子转移来提升甲烷产量.炭源中无机质含量越高,生物炭对SSPL的吸附效果越差,厌氧发酵结束后SSPL的残留量越高;炭源中的碱土金属盐比碱金属盐对厌氧发酵过程更有利.

4 biochars obtained from Phragmites australis and Sporobolus alterniflora were added to the anaerobic co-digestion system of SSPL and cow dung matrix. Batch experiment revealed that biochar addition brought forward the peak day of daily methane yield by 4~8 days and increased the cumulative methane yield by 78.8%~157.2% compared with the controlled group without biochar addition. The promoting effects of the biochars were inversely correlated with the inorganic contents in their raw materials. Biochar addition weakened the microbial bioavailability of SSPL in the liquid by adsorbing its toxic compounds, providing supports and trace elements for microbials, and promoting the interspecific electrical transmission of microbials. The higher the inorganic contents in biochar raw materials, the worse the adsorption performances on SSPL of biochars, which resulted in the higher the organic contents in residues after anaerobic digestion. Biochar raw materials containing alkaline earth metals had better promoting effects on anaerobic digestion than alkali metals when their inorganic contents were similar.