传统生物处理法因硝化菌自身特性(如：好氧自养、世代周期长和对环境变化敏感等)，在低温、成分复杂及高负荷废水等条件下的应用受限。因此，具有生物活性高、环境耐受性好和固液分离容易等特征的固定化硝化菌技术在治理含氮废水方面成为热点。智能水凝胶是可对外界环境刺激做出实时响应(其物理化学性质改变，如：体积发生溶胀-收缩变化)的一类凝胶。论文是在本课题组前期研究基础上对智能凝胶球进一步探究。前期研究已发现核壳结构的智能凝胶球是以海藻酸钙凝胶球(即CA凝胶球)为基材，置于温度/pH 改性溶液中生成温度/pH 响应层。该响应层与同样具有三维网络结构的CA凝胶球相互交织。

本研究采用单因素法分别改变温度改性溶液和 pH 改性溶液中功能单体N-异丙基丙烯酰胺(NIPAAm)和丙烯酸(AA)的含量，以 CA 凝胶球为基材，制备响应凝胶球(如：T、pH、T-pH 和 pH-T 响应 CA 凝胶球)，并运用多种方法对其相关性能进行表征。如：SEM、BET、FT-IR 和接触角等。同时对不同 T(10 和 30℃)和 pH(8 和 10)条件下，六类包埋硝化菌凝胶球(包括：包埋硝化菌 CA 凝胶球、NaCl 改性、T 响应、pH 响应、T-pH 响应和pH-T 响应包埋硝化菌 CA 凝胶球)的硝化作用进行探究。研究内容及结论如下：

从制备适应特殊环境条件(如:低温或高 pH)的包埋硝化菌凝胶球的研究目的出发，结合凝胶球机械性能、溶胀性能和氨氮吸附性能的结果，同时考虑凝胶球的响应性，最终选取 T 响应 CA 凝胶球的最佳合成条件为：温度改性溶液中(10 mL)NIPAAm、N,N’-亚甲基双丙烯酰胺(MBA)、过硫酸铵(APS)和四甲基乙二胺(TMEDA)添加量分别为 225 mg、5 mg、6 mg 和 17 μL。pH 响应 CA 凝胶球的最佳合成条件为：pH 改性溶液中(10 mL)AA、MBA、APS 和 SBS 添加量分别为 100 mg、5 mg、6 mg 和 6 mg。T-pH 和 pH-T 响应CA凝胶球分别在最佳 T 和 pH 响应 CA 凝胶球的基础之上制备而来。T-pH 响应 CA 凝胶球的最佳合成条件为：pH 改性溶液中(10 mL)AA、MBA、APS 和亚硫酸氢钠(SBS)添加量分别为 125 mg、5 mg、6 mg 和 6 mg；pH-T 响应 CA 凝胶球的最佳合成条件为：温度改性溶液中(10 mL)NIPAAm、MBA、APS 和 TMEDA 添加量分别为 225mg、5 mg、6 mg 和 17 μL。

将六类凝胶球(包括：CA 凝胶球、NaCl 改性、T 响应、pH 响应、T-pH 响应和 pH-T响应CA凝胶球)置于硝酸盐氮/氨氮溶液中，溶液中的硝酸盐氮浓度/氨氮浓度随时间增加均呈骤减-小幅递减-平稳变化趋势。各类凝胶球对硝酸盐氮的传质能力明显弱于对氨氮的传质能力，硝酸盐氮去除率和氨氮去除率分别在 7.38%~13.10%和 35.20%~50.01%之间。

在温度为10℃，pH 分别为 8 和 10 两种情况下，包埋硝化菌CA凝胶球均最具优势(pH 为 8 和 10 条件下，第 20 d 的氨氮去除率分别为 37%和57.67%)，其余凝胶球未显示出较好的脱氮性能，pH 响应包埋硝化菌 CA 凝胶球最为突出。在温度为 30℃，pH 为 8 的条件下，pH-T 响应包埋硝化菌 CA 凝胶球在第 5 d 的氨氮去除率可达 80.86%，但使用寿命仅为 8 d。与低温条件(T=10℃)相比，高温条件(T=30℃)更有益于包埋微生物活性的恢复，但后者的使用寿命较短。

The application of traditional biological treatment method is limited in low temperature, complex composition and high loading wastewater due to the characteristics of nitrifying bacteria (e.g., aerobic autotrophic, long generation cycle and sensitive to environmental changes). Therefore, immobilised nitrifying bacteria technology with high biological activity, good environmental tolerance and easy solid-liquid separation has become a hot topic in the treatment of nitrogen-containing wastewater. Smart hydrogels are gels that respond in real time to external environmental stimuli (changes in their physicochemical properties, e.g. dissolution-shrinkage changes in volume). The thesis is a further exploration of smart gel spheres based on the previous research of our group. Previous research has identified core-shell structured smart gel spheres based on calcium alginate gel spheres (CA gel spheres) placed in a temperature/pH modified solution to produce a temperature/pH responsive layer that is interwoven with CA gel spheres that also have a 3D network structure.

In this study, the content of the functional monomers N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) in the temperature-modified and pH-modified solutions were varied by a single-factor method to prepare responsive gel spheres (e.g. T, pH, T-pH and pH-T responsive CA gel spheres) using CA gel spheres as the substrate, and their relevant properties were characterised using various methods, such as SEM, BET, FT-IR and contact angle. The nitrification mechanism of six types of encapsulated nitrifying bacteria gel spheres (including: encapsulated nitrobacter CA gel spheres, NaCl modified, T responsive, pH responsive, T-pH responsive and pH-T responsive encapsulated nitrobacter CA gel spheres) were investigated at different T (10 and 30℃) and pH (8 and 10). The conclusions were as follows:

From the purpose of the study to prepare encapsulated nitrifying bacteria gel spheres with good environmental tolerance (e.g.: low temperature and high pH), the results of the mechanical properties, swelling properties and ammonia nitrogen adsorption properties of the gel spheres were combined with the responsiveness of the gel spheres, and the optimal synthesis conditions for T responsive CA gel spheres were finally selected as follows: temperature modified solution with (10 mL) NIPAAm, MBA, APS and TMEDA added at 225 mg, 5 mg, 6 mg and 17 μL, respectively. The optimal synthesis conditions for pH responsive CA gel spheres were: pH modified solution with (10 mL) AA, MBA, APS and SBS added at 100 mg, 5 mg, 6 mg and 6 mg, respectively. T-pH and pH-T responsive CA gel spheres were prepared on the basis of optimal T and pH responsive CA gel spheres, respectively. The optimal synthesis conditions for T-pH responsive CA gel spheres were: pH modified solution with (10 mL) AA, MBA, APS and SBS added at 125 mg, 5 mg, 6 mg and 6 mg, respectively. The optimal synthesis conditions for pH-T responsive CA gel spheres were: temperature modified solution with (10 mL) NIPAAm, MBA, APS and TMEDA added at 225 mg, 5 mg, 6 mg and 17 μL, respectively.

Six types of gel spheres (including: CA gel spheres, NaCl modified, T-responsive, pH-responsive, T-pH-responsive and pH-T-responsive CA gel spheres) were placed in nitrate nitrogen/ammonia nitrogen solution, and the nitrate nitrogen concentration/ammonia nitrogen concentration in the solution all showed an abrupt decrease-a small decrease-a steady trend with increasing time. The mass transfer capacity of the various gel spheres for nitrate nitrogen was significantly weaker than that for ammonia nitrogen, with nitrate nitrogen removal and ammonia nitrogen removal rates of 7.38%-13.10% and 35.20% -50.01%, respectively.

 In both cases of temperature 10°C and pH 8 and 10, respectively, the encapsulated nitrifying bacteria CA gel spheres were the most dominant (37.00% and 57.67% of ammonia nitrogen removal at pH 8 and 10 at 20 d, respectively). The rest of the gel spheres did not show better nitrogen removal performance, and the pH responsive encapsulated nitrobacter CA gel sphere was the most prominent. At a temperature of 30°C and pH of 8, the pH-T response encapsulated nitrobacter CA gel spheres achieved 80.86% ammonia nitrogen removal on day 5, but the service life was only 8 d. High temperature conditions (T=30°C) were more beneficial for the recovery of the activity of the encapsulated microorganisms than low temperature conditions (T=10°C), but the latter had a shorter lifetime.