改性壳聚糖/活性炭复合吸附颗粒耦合微生物低温除氨氮协同反应机理与稳定性控制

Chitosan and chitosan derivatives have gained wide attention as effective biosorbents due to low cost and high contents of amino and hydroxyl functional groups which show significant adsorption potential for the removal of various aquatic pollutants. Also the chitosan can be used as a support for the preparation in the form of particles with granular activated carbon to improve mechanical strength, or immobilized with dominant bacteria for high removal efficiency. For this reason, a new chitosan biopolymer derivative synthesized by crosslinked granular activated carbon and anchored with dominant bacteria, called “Chitosan crosslinked Biological Granular Activated Carbon” process, ”CBC” for short, will be investigated in this study. The CBC process will be employed to instead the traditional drinking water treatment process for ammonia (NH4+-N), especially on the condition of low temperature（<10℃）. .The study will include the cooperation and the stabilization mechanism of the biological chitosan crosslinked granular activated carbon. The surface chemistry and molecular biology technique will be used for the uptake mechanism and sorption performances of ammonia by CBC process. Also the cooperative formation of intermediate product、reaction process and the interreaction between the chitosan crosslinked GAC and dominant bacteria and the optimal process parameters of the CBC under different factors will be investigated. Pseudo-first order, pseudo-second order and Dubinnin-Radushkevich models will be analyzed. The equilibrium data will be analyzed using Langmuir, Freundlich and Redlich-Peterson isotherms. The new chitosan material will be characterized by spectral (FTER),thermal, structure, and morphological(SEM) analysis. The dominant bacteria immobilized on the chitosan derivative will be characterized by PCR-DGGE, FISH, ATP and biomass analysis. The intermediate products with N elemental will be identified by the elemental(CHN), atomic absorption spectroscopy analysis. The results of this study will improve the new technology of ammonium treatment process under low temperature and guarantee the safety of drinking water for human beings.

针对北方地区传统工艺难以在低温条件下处理氨氮的问题，采用“改性壳聚糖交联颗粒活性炭固载优势菌”的方法构建一种新型生物复合吸附颗粒，利用改性壳聚糖表面多功能活性官能团对氨氮的化学吸附作用、低温除氨氮优势菌的高效生物反应作用、颗粒活性炭的稳定机械强度、以及抗有机负荷性能，将三者进行耦合，形成具有耐低温、高稳定的新型水处理材料。本课题通过采用表面化学、分子生物学等分析手段揭示生物复合吸附颗粒低温除氨氮过程组分内部壳聚糖、活性炭、优势菌三者协同反应效率、反应流程、基质与产物转化关系，同时揭示生物复合吸附颗粒低温除氨氮过程壳聚糖交联颗粒活性炭吸附性能与优势菌反应活性、数量、胞外分泌物之间相互影响关系，分析外部环境因素（低温、溶解氧、污染负荷等）对生物复合吸附颗粒反应稳定性的影响机制，建立保持生物复合吸附颗粒低温除氨氮高效稳定性的最优控制参数，为生物复合吸附颗粒在水处理领域的应用和机理探究提供理论依据

针对我国北方地区地下水源受氨氮的污染问题，通过构建一种“改性壳聚糖/沸石分子筛复合吸附颗粒”，利用多功能高分子材料—改性壳聚糖对硝酸盐氮的吸附作用，同时利用沸石分子筛丰富的孔隙结构、稳定的机械强度、以及对氨氮的高效离子交换作用，将两者通过交联的方法进行耦合，形成集吸附作用、离子交换作用为一体的新型水处理材料，达到去除水中氨氮和硝酸盐氮的作用。试验结果表明：壳聚糖/沸石分子筛吸附颗粒的最佳制备条件为乙酸浓度为4vol%，壳聚糖浓度为7g/L，振荡时间为10h，振荡温度为30℃，制得的吸附颗粒对氨氮和硝酸盐氮的吸附量分别达到0.636mg/g和1.952mg/g，去除率分别为81.60%和40.28%。颗粒表面形貌呈现较多凸起和微孔，颗粒的比表面积为391.52m2/g；FTIR分析结果表明壳聚糖特征官能团NH2-和CH3-已负载于沸石分子筛的基本骨架中；XPS分析结果表明元素O (1s)在壳聚糖与沸石分子筛的连接过程起主要作用。通过研究不同影响因素，包括原水浊度，pH值，温度对复合吸附颗粒吸附氨氮与硝酸盐氮的影响规律。试验结果表明：原水浊度范围对NH4+-N，NO3--N的去除有较大的影响；在温度为5-30℃范围内，氨氮与硝酸盐氮的去除效果均呈现逐渐增大的趋势；当原水的pH值介于6-7时，复合吸附颗粒对NH4+-N，NO3--N的去除效果较好。当原水NH4+-N与NO3--N浓度分别为5mg/L与30mg/L时，采用改性CTS/沸石分子筛投加量为6.5-7g/L，吸附时间为6-6.5h，氨氮与硝酸盐氮的去除率达到最大，分别为80%与40%。通过吸附动力学、吸附等温线及吸附热力学对再生机理进行研究，结果表明再生后的壳聚糖改性沸石分子筛对氨氮和硝酸盐氮的吸附过程符合准二级动力学模型，吸附过程为化学吸附；吸附和分析复合颗粒再生前后物化特性，结果表明吸附氨氮和硝酸盐氮的CTS-Z表面出现大面积杂质，再生后能够部分恢复凹凸不平的网状结构，再生前后吸附颗粒主要元素为Si、Al和O元素，孔径和孔容积也有一定程度增大，再生前后复合颗粒仍然呈硅铝氧骨架。