包埋固定化硝化污泥处理氨氮废水的过程特性

Process characteristics of ammonia wastewater treatment by embedded immobilized nitrifying sludge

采用聚乙烯醇(PVA)包埋硝化效能良好的活性污泥制备固定化颗粒,针对不同初始氨氮浓度的模拟废水,基于序批式间歇反应器小试实验,探讨了包埋颗粒的传质效能与氮去除过程特性.实验结果表明:颗粒体积投加率为10%,实验水温为26~30℃,pH值为7.5~8.5,反应器DO浓度为4~5mg/L的条件下,各初始氨氮浓度(50~400mg/L)稳定期包埋颗粒最大氨氮去除负荷为61.8~242.3mg N/(L-particles·h).包埋颗粒对氨氮的去除较符合零级反应动力学模型,其最大氨氧化速率(μmax)为271.40mg N/(L-particles·h),半饱和常数K_s为66.69mg/L,包埋颗粒内氨和氧的有效扩散系数(D_e)分别为0.467×10^(-9)m^2/s、0.279×10^(-9)m^2/s.SEM观察和比表面积测试结果表明,与新鲜颗粒相比,稳定期颗粒内部的比表面积和平均孔径增加.包埋颗粒,活性污泥,包埋颗粒与活性污泥混合3种体系对比实验表明,各初始氨氮浓度条件下混合体系可显著强化生物硝化与脱氮过程,并发生同时硝化反硝化现象.

Polyvinyl alcohol（PVA） as a gel matrix was used to immobilize activated sludge with good nitrification performance. The mass transfer efficiency and nitrogen removal characteristics of immobilized particles were evaluated for different initial ammonium concentration of simulated wastewater in the sequencing batch reactor（SBR）. When the package percentage of immobilized particles, water temperature, pH, and the DO concentration were 10%, 26-30℃, 7.5-8.5, and 4-5mg/L, respectively, the maximal ammonia removal load in the stable period kept at 61.8-242.3mg N/（L-particles·h） with different influent NH_4-＋-N concentration of 50-400mg/L. The removal kinetics of ammonia nitrogen followed the zero-order reaction model, furthermore, the maximum ammonia oxidation rate（μmax） and half-saturation constant（Ks） were estimated as 271.40 mg N/（L-particles·h） and 66.69mg/L, respectively. According to the diffusion experiments, the effective diffusion coefficient（D_e） of ammonia and oxygen in immobilized particles were calculated as 0.467×10-（-9）m-2/s and 0.279×10-（-9）m-2/s, respectively. SEM observation and the test of specific surface area showed that the specific surface area and the average pore diameter in the interior of the particles increased greatly during the stable stage compared with the fresh particles. Comprehensive comparison of three different systems including immobilized particles reactor, activated sludge reactor, and the mixing reactor with immobilized particles and activated sludge was carried out. The sludge reactor with adding immobilized particles could enhance the nitrification and nitrogen removal process significantly. Moreover, the simultaneous nitrification and denitrification also could be observed.