重金属污染的菊芋茎秆沼气化性能及蓄积重金属的归趋

STUDY OF HEAVY METAL IN AANAEROBICALLY DIGESTING HELIANTHUS TUBEROSUS STRAW HARVESTED FROM HEAVY METAL POLLUTED SOIL

利用菊芋(Helianthus tuberosus)进行重金属污染土壤修复会产生大量秸秆废弃物,通过厌氧消化将其转化为沼气,是其资源化利用途径之一。为了评估该处置技术的环境风险,实验以重金属污染土壤种植的菊芋茎秆为对象开展厌氧消化研究,对其产气性能、重金属形态变化、可迁移能力及生物有效性进行评估。结果表明,菊芋秸秆中茎主要重金属(Cu,Zn,Pb,Cr,Cd)含量为5.69×10^(-6),19.19×10^(-6),0.23×10^(-6),0.33×10^(-6),0.50×10^(-6),叶中的含量分别为9.11×10^(-6),23.83×10^(-6),0.57×10^(-6),0.43×10^(-6),0.48×10^(-6)相对与根与块茎较较高;菊芋秸秆厌氧发酵总产气量为206.58 ml·g^(-1) TS,显示产气潜力良好;厌氧消化后,Cu,Pb和Cr的重金属可迁徙因子值低,相对比较稳定,迁移能力较弱。Cr和Cd的生物可利用度减小,其中Cr大幅度减小了41.54%,Cd减小了12.30%,说明厌氧消化能有效降低Cr和Cd的生物可利用度,减小对环境的危害。但Pb的生物有效性大幅度上升,应在沼渣管控环节关注。

Application of Helianthus tuberosus to remediation of heavy metal contaminated soil will produce a large amount of straw wastes.Anaerobically digesting the obtained waste straw is a potential way for valorization.Helianthus tuberosus straws from heavy metal polluted soil are used for anaerobic digestion and its gas production performance,heavy metal morphology,migration ability and bioavailability for control of heavy metal-contaminated soil and development of green renewable energy are evaluated.It shows that content of heavy metals includes Cu(5.69×10^-6),Zn(19.19×10^-6),Pb(0.23×10^-6),Cr(0.33×10^-6) and Cd(0.50×10^-6) in stalk,and their content in leaves is 9.11×10^-6,23.83×10^-6,0.57×10^-6,0.43×10^-6,0.48×10^-6,respectively,mostly lower than those in roots and tubers.In anaerobic fermentation,total gas production of 206.58 ml·g^-1 TS reflects good gas performance.Before anaerobic digestion,Zn and Cd exist mainly in a relatively unstable state,while Cu,Cr and Pb exist mainly in a more stable state.Effective state of Cu,Pb and Cr remains at a very low level,with a small potential harm.Except that the proportion of Cr and Cd in the stable state is greatly increased,the remaining heavy metals change from stable to unstable states.Cd exhibits strong biological activity,instability and migration ability while potential harm of other heavy metals is not significantly harmful to environment.