“镉米”生物能源化过程中Cd的迁移途径

Transfer route of Cd in process of cadmium rice biological energy

镉属于环境中持久性污染物,毒性大,对环境及人类造成严重危害,＂镉米＂事件已引起了对环境镉污染尤其是土壤镉污染的高度关注。利用镉米生产酒精不但能为企业能源生产提供新的原料来源,而且可解决有害大米的出路问题。通过摇瓶和UASB厌氧反应器实验,重点研究了Cd2＋在厌氧处理过程中的迁移途径。结果表明,90%以上的Cd2＋主要以微溶的形式富集于厌氧污泥里。厌氧泥离心分离：泥中镉浓度为0.35～0.40 mg/kg,水中镉浓度低于0.025 mg/kg。厌氧出水镉浓度在0.010～0.015 mg/kg,可以实现达标排放。出水VFA基本维持在300～500 mg/L,COD的去除率达65%～80%。实验结果可为镉米能源化利用提供一定的理论依据和技术支撑。

Cadmium（ Cd） is a toxic and persistent pollutant that threatens the environment and human health. The incident of ＂cadmium rice,＂or rice found to be laced with the metal Cd,has attracted much attention to the problem of Cd pollution,especially Cd-contaminated soil. Alcohol production with cadmium rice not only can provide new raw material resources for enterprise energy production,but also can solve the problem of harmful rice. The migratory route of Cd in the process of anaerobic treatment was studied through shaking flask and upflow anaerobic sludge blanket（ UASB） reactor experiments. The results showed that more than 90% of Cd2 ＋was enriched in the anaerobic sewage sludge in semisoluble forms. After centrifuging,the Cd concentration in the anaerobic sewage sludge was 0. 35 to 0. 40 mg / kg and the Cd concentration in water was less than 0. 025 mg / kg. The Cd concentration in the anaerobically digested effluent was 0. 010 to 0. 015 mg / kg,and the water quality could reach the discharge standards. The volatile fatty acids（ VFA） of the effluent were maintained at300 to 500 mg / L and the chemical oxygen demand（ COD） removal efficiency reached 65% to 80%. The experimental results can provide a certain theoretical basis and technical support for energy utilization of cadmium rice.