微生物介导下的Fe(II)/Fe(III)循环转化实现地下水硝态氮还原的调控

Based on the needs of deep denitrification treatment for groundwater, the course of development and perfection of denitrification is task worthy to research. The nitrate-reducing is urgently needed to be solved. It is a strategic subject to break through the bottleneck on the nitrate removal in groundwater. According to the principle of local electrochemistry, this proposal for the first time conceives the controllable reduction of nitrate in groundwater by novel Fe(II)/Fe(III)-LDH with the multi-media and multi-interface process. For this purpose, the following work should be carried out that includes the study on the tunable structure of Fe(II)/Fe(III)-LDH which containing other ion, the investigation on the redox potential according to temperature, acidity and concentration of the system, and dynamics from the nitrate-reducing and organic micro-pollutants degradation process. We attempt to obtain the mechanism of the local electrochemical process in multi-media and on multi-interface for the nitrate-reducing in groundwater by Fe(II)/Fe(III)-LDH. Moreover, the controlling object of the transformation from nitrate to gaseous nitrogen can be rapid realized effectively through the controlling methods including mastering the evolution rule of reduction, and exterminating of the intermediate and final products of the process, and proving the dynamics and micro-mechanism of nitrate-reducing and organic micro-pollutants degradation process. The Fe(II)/Fe(III) circular transform can be achieved at the same time. The research results of this proposal are scientifically valuable and practically directive to the nitrate-reducing in groundwater treatment.

为满足地下水深度脱氮处理的需求，以弄清地下水中硝态氮还原去除过程多介质多界面生物无机化学控制原理为根本，利用Fe(II)Fe(III)化合物和有机微污染物的脱氮作用，及微生物介导下的Fe(II)/Fe(III)循环，设计“Fe(II)Fe(III)-N-C-微生物”反应体系，通过对Fe(II)/Fe(III)化合物组分结构的设计调控、硝态氮还原和有机微污染物降解过程的Eh调控等手段，系统研究地下水硝态氮在Fe(II)/Fe(III)化合物-微生物界面的生物无机化学行为、还原转化规律、中间/最终产物、反应动力学及其还原转化过程的作用机制，实现Fe(II)/Fe(III)循环转化及硝态氮向气态氮转化的调控目标，研究成果有望为地下水中硝态氮的去除提供理论指导。

为满足地下水深度脱氮处理的需求，弄清地下水中硝态氮还原去除过程多介质多界面生物无机化学控制原理，利用Fe(II)Fe(III)化合物和有机微污染物的脱氮作用，构建了一系列微生物介导下的Fe(II)/Fe(III)循环反应体系。研究结果有望为地下水中硝态氮的去除提供理论指导，具体包括：1、硫酸盐绿锈中掺杂Cu和Al，可控制其对硝酸盐的还原速度和产物。引入Cu(II)硝酸盐还原率提高3.5倍，Al(III)取代使硝酸盐转变为亚硝酸盐，还可能产生如NO、N2O和N2。pH=9时，Cu(II)=3%，r=Al(III)/[Fe(III)+Al(III)]=20%，总氮去除率高达25%。2、“S.oneidensis MR-1-Fe-NO2-”体系中，硝酸盐还原在170h内完成。初始阶段，硝酸盐去除的主要贡献来自于S.oneidensis MR-1的生物还原过程，同时还伴随着Fe(III)还原。后续阶段，生物源Fe(II)氧化与硝酸盐还原同时发生，水铁矿和磁铁矿体系中，分别产生了47.33%和16.8%的气态氮。不同Fe、N形态等氧化还原反应存在差异，其中NH4+生成主要来源于S.oneidensis MR-1还原NO3-转化路径，气态产物N2O、NO2生成主要由体系中Fe2+与NO2-/NO3-发生氧化还原反应，NO3-/NO2-与铁矿物、微生物之间形成生物化学行为及还原转化过程作用机制，完成微生物介导下的Fe(II)/Fe(III)循环。3、“S.oneidensis MR-1-Fe-NO2-”体系中，运行阶段NO2-被Fe2+还原去除，产物为NH4+和气态氮，Fe2+则被氧化为Fe3+，即完成微生物介导下的Fe(II)/Fe(III)循环转化。4、“S.oneidensis MR-1-NO2-硝基苯NB”体系中，50h内NO2-和NB的去除率分别为27.68%和13.85%，与S.oneidensis MR-1单独体系相比，去除率分别降低72.18%和86.15%。当亚硝酸盐氮和硝基苯同时存在时，会相互抑制彼此的微生物还原过程，且抑制作用较大。5、还进一步开展了生物源Fe(II)固磷生成蓝铁矿实现磷回收的研究。通过铁还原工艺与改变投磷时间相结合，可提高磷的回收率。