不同碳氮比下后置反硝化工艺中溶解性有机质的分子特征及其转化机理  

Molecular characteristics and transformation mechanism of dissolved organic matter in post-denitrification process at different carbon-to-nitrogen ratios

作　　者：崔贤 程华仔 韩成龙 丁丽丽[1] 胡海冬 任洪强[1] CUI Xian;CHENG Huazai;HAN Chenglong;DING Lili;HU Haidong;REN Hongqiang(State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing,210023,China)

机构地区：[1]南京大学环境学院,污染控制与资源化研究国家重点实验室,南京210023

出　　处：《环境化学》2024年第8期2658-2671,共14页Environmental Chemistry

基　　金：国家自然科学基金(52170036)资助.

摘　　要：污水处理厂后置反硝化工艺中外加碳源的投加量会影响出水溶解性有机质(DOM)的特性,从而影响后置反硝化的处理效率和出水水质.本研究以实际污水中DOM为研究对象,利用傅里叶变换离子回旋共振质谱(FT ICR-MS)开展了不同碳氮比(C/N=3、4、5、6)下后置反硝化工艺中DOM的分子特征及其转化机理研究.结果表明,在4种C/N下,C/N=5的反应器出水芳香性DOM分子(AImod>0.5)和不饱和程度高的分子(DBE≥4)占比最高,分别为24.72%和97.6%,说明C/N=5时,出水难生物降解程度较高.通过分子转化分析可知,C/N=5的反应器产生的DOM分子占比(58.35%)最高且不饱和程度较高,去除的分子占比(2.80%)低且不饱和程度较低,再次证实C/N=5的反应器出水相较于C/N=3、4、6的反应器出水DOM分子惰性高,排放至受纳水体环境风险较低.此外,微生物群落结构及其与DOM的关联分析可知,Proteobacteria在C/N=5的反应器中相对丰度最高,其主导后置反硝化工艺中DOM分子的产生,Planctomycetota、Nitrospirota、Chloroflexi和Gemmatimonadota对DOM分子的去除和产生也具有重要作用.综上所述,推荐C/N比为5作为后置反硝化工艺中外加碳源的适宜C/N比.The dosing of external carbon sources will affect the characteristics of effluent dissolved organic matter(DOM),the treatment efficiency,and effluent quality in the post-denitrification process of wastewater treatment plants.In this study,the molecular characteristics and conversion mechanism of DOM in the real wastewater were investigated by Fourier transform ion cyclotron resonance mass spectrometry(FT ICR-MS)in post-denitrification process at different carbon to nitrogen ratios(C/N=3,4,5 and 6).The results showed that the proportion of aromatic DOM molecules(AImod>0.5,24.72%)and unsaturated molecules(DBE≥4,97.6%)in the effluent from the reactor at C/N ratio of 5 were the highest between four reactors.It indicated that DOM molecules at the C/N ratio of 5 were more refractory in the effluent.The transformation of DOM molecular showed that the proportion of produced DOM molecules(58.35%)with high unsaturated index was the highest in the reactor at C/N ratio of 5,and the proportion of removed DOM molecule(2.80%)was lowest with low unsaturated index.This again conformed that the DOM molecular inertness of the effluent from the reactor at C/N ratio of 5 was higher than that from the reactor at C/N ratio of 3,4,and 6,which is not prone to create environmental risk.In addition,the relationship between microbial community structure and DOM showed that Proteobacteria dominated the production of DOM molecules in the post-denitrification process,which had highest relative abundance from the reactor at C/N ratio of 5.Planctomycetota,Nitrospirota,Chloroflexi and Gemmatimonadota are also important for the removal and production of DOM molecules.In summary,the C/N ratio of 5 is recommended as the appropriate C/N ratio for external carbon source in the post-denitrification process.

关 键 词：溶解性有机质 (DOM) 后置反硝化 傅里叶变换离子回旋共振质谱 (FT ICR-MS) 微生物群 落 污水处理. 

分 类 号：X-1[环境科学与工程] O6[理学—化学]