新型LDHs基缓释碳源的制备及应用

Preparation and application of a novel LDHs-based slow-release carbon source

以羟甲基纤维素钠(CMC)为负电离子,选用4种金属离子(Fe^(3+)、Al^(3+)、Ni^(2+)、Mg^(2+)),以共沉淀法制备4种基于层状双金属化合物(LDHs)的缓释碳源材料.采用X射线衍射(XRD)、X射线光电子能谱(XPS)和缓释性能分析,筛选出释碳量大、稳定缓释的FeNi-LDH-CMC碳源材料.通过响应面实验确定了FeNi-LDH-CMC、聚乙烯醇(PVA)、CMC的最佳质量分数为7.77%、4.02%、1.02%,此时制备的LDHs基滤料释碳系数为4.40,最大COD释放值为320.96 mg·g^(−1).最后构建反硝化生物滤池,对模拟低碳氮比废水进行脱氮处理.结果表明,HRT=3 h时,反硝化滤池对TN平均去除率仅为32.4%,氮负荷为(0.0960±0.0082)kg·m^(−3)·d^(−1) N,而投加LDHs基滤料使滤池TN去除率提高了35.32%—38.46%,氮负荷提高了(0.118±0.0092)kg·m^(-3)·d^(−1) N;在投加LDHs基滤料后,5种反硝化功能基因(napA、narG、nirS、nirK、nosZ)的丰度均有显著增加(P<0.05),提高了反硝化的各个阶段脱氮效率.研究结果表明LDHs基缓释碳源在反硝化滤池中可强化低碳氮比废水深度脱氮,是一种潜在应用于废水深度脱氮的新型材料.

This study took the lead in using sodium hydroxymethyl cellulose(CMC)as the negative ion and four kinds of metal ions(Fe^(3+),Al^(3+),Ni^(2+)and Mg^(2+))to prepare layered bimetallic compounds(LDHs)-based slow-release carbon source materials by coprecipitation method.FeNi-LDH-CMC with the charecteristics of large amount and stable slow-release of carbon was screened out through X-ray diffraction(XRD),X ray photoelectron spectroscopy(XPS)and slow-release performance analyses.The optimum mass fraction of FeNi-LDH-CMC,polyvinyl alcohol(PVA)and CMC was determined as 7.77%:4.02%:1.02%by response surface experiment,to achieve the carbon release coefficient of 4.40 and the maximum chemical oxygen demand(COD)release of 320.96 mg·g^(−1) of the prepared LDHs-based filter media.Finally,denitrification biological filter was constructed for denitrogenation of synthetic wastewater with low C/N ratio.Results showed that under HRT of 3 h,the average removal rate of total nitrogen(TN)was only 32.4%and the nitrogen load was(0.0960±0.0082)kg·m^(-3)·d^(−1) N.By contrast,TN removal rate and nitrogen load were increased by 35.32%—38.46%and(0.118±0.0092)kg·m^(-3)·d^(−1) N,respectively,after the addition of LDHs-based filter media.The abundances of five denitrifying functional genes(napA,narG,nirS,nirK and nosZ)were also significantly increased(P<0.05),which improved the denitrogenation efficiency at each stage of denitrification.It demonstrated that LDHs-based slow-release carbon source could strengthen the deep denitrogenation of wastewater with low C/N ratio in denitrification biological filter,and could be employed as a potentially novel material for advanced denitrogenation of wastewater.