反硝化条件下河流沉积层中苯降解的实验研究——硝态氮与亚硝态氮共存时  

Experimental Study on the Degradation of Benzene in Riverbed Sediments under Denitrification Conditions——When Nitrate and Nitrite Coexist

作　　者：张悦周[1] 吴耀国[1] 李想[1] 尹德忠[1] 

机构地区：[1]西北工业大学理学院应用化学系,陕西西安710072

出　　处：《西北工业大学学报》2008年第1期25-29,共5页Journal of Northwestern Polytechnical University

基　　金：国家自然科学基金(40472127)资助

摘　　要：在"反硝化条件下沉积层中苯降解"尚存在争议及"亚硝态氮对苯降解具有抑制作用"的背景下,文中考察了反硝化条件下河流沉积层中苯降解的可能性,重点研究了亚硝态氮与硝态氮共存时,亚硝态氮对苯降解的影响。结果表明,实验过程中虽有亚硝态氮出现,反硝化条件下河流沉积层中苯仍可降解;亚硝态氮的存在不仅没有抑制苯降解,相反还具有促进作用;但促进作用的发挥与亚硝态氮浓度有关。当总氮(亚硝态氮与硝态氮浓度之和)初始浓度约为250 mg/L,亚硝态氮、硝态氮浓度分别约为160 mg/L与60 mg/L时,亚硝态氮对苯降解的促进效果最优;当硝态氮初始浓度约为21 mg/L时,亚硝态氮约为106 mg/L时对苯降解的促进效果最优。实验条件下,亚硝态氮浓度的减少速率及反应速率常数都大于硝态氮的,表明亚硝态氮优先于硝态氮作为电子受体而被使用。因而,利用亚硝态氮,尤其是硝态氮低浓度条件下,强化反硝化条件下河流沉积层中苯降解是可行的。The microcosm tests were conducted to research the possibility of benzene degradation and the effect of nitrite on the degradation in riverbed sediments with the coexistence of nitrite and nitrate under denitratification conditions. The results show that, although nitrite appears and accumulates in certain content, benzene is degraded in the riverbed sediments under denitrafication conditions. The presence of nitrite has a potential to enhance benzene degradation instead of inhibiting the degradation, and the potential depends on the concentration of nitrite. When the total concentration of nitrate and nitrite was about 250 mg/L, nitrite with the concentration of 160 mg/L has an optimum potential to enhance the degradation. however, when the concentration of nitrate was 21 mg/L, nitrite with the concentration of 106 mg/L has an approximative potential. During all the test processes, the reaction rates and their rate constants of nitrite are greater than that of nitrate. That shows that nitrite has a priority to be used as an electron-acceptor. Therefore, nitrite can be used to enhance benzene degradation in riverbed sediments under denitrification conditions, especially, when the concentration of nitrate is low.

关 键 词：苯 河流沉积层 反硝化条件 亚硝态氮 硝态氮 

分 类 号：X172[环境科学与工程—环境科学]