底泥就地稳定化中零价铁(Fe^0)对有机污染物的作用及其对上覆水体水质的影响

Effect of zero-valent iron on organic pollutants in sediment and the related overlying water during in-situ treatment

在实验室模拟静态湖泊体系条件下,通过向实际底泥中投加零价铁(Fe^0),考察反应前后底泥中有机物数量、种类、总有机质含量以及上覆水体溶解氧(DO)浓度、氧化还原电位(Eh)、pH和化学需氧量(CODCr)浓度等指标的变化,探讨Fe^0对底泥有机物的降解效果以及对上覆水体水质的影响.结果表明,投加Fe^0处理80 d后,(1)经GC-MS检测出底泥中易被降解的小分子有机物(分子量小于200)数量明显增多,底泥总有机去除率为44%.(2)上覆水体的DO浓度、Eh和pH都有不同程度的变化.DO浓度从6.6 mg/L迅速下降至0.2 mg/L,Eh从150 mV左右下降至74 mV,pH升高至8.4,此体系易形成厌氧环境;且上覆水体中CODCr低于纯底泥-水体系,上覆水中DO浓度、Eh及pH与CODCr浓度具有一定相关性.综上,底泥中投加Fe^0可有效降解有机物,且不会对上覆水体产生持久、较大的影响.

Based on the laboratory simulates a static lake system,the removal of organic pollutants in sediments using zero-valent iron（ Fe0） for in-situ sediment treatment was studied. The effects of zero valent iron（ Fe0） on the overlying water including DO,Eh,pH and CODCrwere investigated and the effects on the sediments including the number and kinds of organic pollutants,total organic content were discussed. The results showed that with adding Fe0 for treating 80 days,（1） the amount of low-molecularweight organics（ of below200） were increasing apparently which could be easy to degrade detecting by GC-MS. The removal rate of organic content in sediments was around 44%.（2） the value of pH was rising to 8.4,while the Eh was declining from 150 mV to 74 mV and the DO concentration of overlying water depleted dramatically from 6.6 mg/L to 0.2 mg/L. The system formed an anaerobic environment. CODCrconcentration of overlying water was lower than that in pure bottom-water system. In addition,there were certain relations among DO,Eh,pH and CODCrin overlying water. In conclusion,the removal of organic pollutants was effective by adding Fe0 in the sediments,and this effect on overlying water quality was not permanent and seriously.