酸碱预处理对水稻秸秆厌氧消化中重金属释放的影响

Effect of Acid and Alkali Pretreatment on Release of Heavy Metals by Anaerobic Digestion of Rice Straw

为探究含重金属秸秆类生物质厌氧消化的可行性,以酸碱预处理后水稻秸秆为消化底物,探究其厌氧消化特性及重金属释放规律。研究结果表明,经6%NaOH预处理的水稻秸秆厌氧消化沼气产量达446.3 mL/g_(VS),秸秆中Cd、Pb、Cu和Zn的释放率分别达到96.08%、89.55%、86.95%和92.82%;经3%H_2SO_4预处理的水稻秸秆沼气产量为396.9 mL/g_(VS),秸秆中Cd释放率为93.96%,而Pb、Cu和Zn释放率均低于80.00%。碱预处理降解秸秆中木质素,酸预处理降解半纤维素,厌氧消化降解利用木质纤维素等过程实现了水稻秸秆中重金属的高效释放。化学预处理尤其是NaOH预处理水稻秸秆可以促进其厌氧消化产沼气和重金属释放,实现含重金属生物质的安全处置和资源化利用。

The heavy metal-containing rice straw,after pretreated with NaOH or H2SO4 solution,was adopted as a digestive substrate to explore the anaerobic digestion characteristics and release mechanism of heavy metals by anaerobic digestion. The results showed that,after pretreatment with 6% NaOH,the biogas yield from anaerobic digestion of rice straw reached 446.3 mL /gVS and the release rates of Cd,Pb,Cu and Zn were 96.08%,89.55%,86.95% and 92.82%, respectively. And after pretreatment with 3% H2SO4 ,the biogas yield of rice straw was 396.9 mL /gVS and the release rate of Cd from straw was 93.96%,while release rates of Pb,Cu and Zn were all lower than 80.00%. It is found that due to the degradation of the lignin and hemicellulose in the straw by alkali and acid pretreatment,respectively,plus the degradation of lignocellulose by anaerobic digestion,the efficient release of the heavy metals from rice straw can be realized. Chemical pretreatment,especially pretreatment of rice straw with NaOH,can promote the yield of biogas and release of heavy metals by anaerobic digestion,thus achieving the purpose of safe disposal of heavy metal-containing biomass,as well as resources utilization.