• 关键词：多级土壤渗滤系统  固相碳源  低污染水  强化脱氮

• 基金项目：国家自然科学基金面上项目（No.50978001）；国家“水体污染控制与治理”科技重大专项（No.2012ZX07102002）

• 吴浩恩
• 北京大学环境科学与工程学院, 北京 100871

• 魏才倢
• 北京大学环境科学与工程学院, 北京 100871

• 吴为中
• 北京大学环境科学与工程学院, 北京 100871

• 摘要：采用"微曝气+缺氧"的两段式多级土壤渗滤系统（multi-soil-layering system，MSL）工艺，建立了在缺氧段模块中添加不同碳源的MSL系统并进行脱氮效率对比.其中，MSL1系统添加了传统碳源木屑，MSL2系统添加了一种基于PHBV（聚羟基丁酸戊酸酯）的共混固相碳源（GC-4）.通过10个月的连续运行，深入探讨碳源、水温、表面水力负荷等条件对该工艺脱氮性能的影响.整个运行过程期间不同条件影响下，添加新型固相碳源的MSL2比MSL1表现出更好的强化脱氮性能.在相同表面水力负荷（1.0 m³·m^-2·d^-1）条件下，水温的降低会直接降低系统的脱氮效率.当水温从平均19℃下降到<15℃时，MSL1系统对NH₄⁺-N、TN的平均去除率分别由91%、62%下降为81%、45%，MSL2系统对NH₄⁺-N、TN的平均去除率分别由88%、72%下降为80%、55%，但MSL2系统仍然优于MSL1系统.水力负荷的降低会提高2个系统TN去除率大约20%，证明了低水力负荷利于系统的脱氮效果.在各个运行阶段，MSL系统添加固相碳源均没有出现碳源过度释放现象，表现出较好的COD去除效果.分子生物学研究揭示了两段式MSL系统中微生物、硝化菌、反硝化菌的功能分区及其丰度，在生物量和反硝化基因数量上MSL2均大于MSL1，硝化菌（amoA基因）集中分布在微曝气段，反硝化菌（nirS、nirK）集中分布在土壤模块层，比较好的解释了不同碳源类型条件下MSL系统的脱氮效果的差异性.

• Abstract：The MSL (multi-soil-layering, MSL) systems with one aerobic stage and one anaerobic stage were set up for the low pollutant loading wastewater treatment. The denitrification effect in anaerobic stage was enhanced by external carbon source addition, which were selected as the sawdust for MSL1 system and the PHBV (poly-3-hydroxybutyrate-co-3-hydroxyvalerate) mixed GC-4 carbon source for MSL2 system. Operation conditions including temperature and hydraulic loading were varied for system performance evaluation. When the hydraulic loading was 1.0 m³·m^-2·d^-1, the denitrification efficiencies of both two MSL systems were decreased when the inflow temperature was decreased from ~19℃ to <15℃. The average NH₄⁺-N and TN removal efficiencies of MSL2 were reduced from 91% to 45% and from 81% to 62%, respectively. For MSL2 system, the average NH₄⁺-N and TN removal efficiencies were reduced from 88% to 80% and from 72% to 55%, respectively. There results demonstrate an obviously better nitrogen removal performance of MSL2 system with GC-4 comparing with MSL1 with sawdust. In addition, the TN removal efficiencies of both two MSL systems were enhanced for about 20% under lower hydraulic loading, indicating that a more sufficient contact between the slower water flow and the carbon source can benefit the denitrification efficiency. Basically, there were no excessive carbon source release phenomenon occurred since the average COD removal efficiencies of MSL2 were maintained at about 40%. The function division and abundances of microorganism, nitrification bacteria, and denitrification bacteria were studied by molecular biological approach. The results show that the biomass and the denitrification gene abundance in MSL2 system were obviously more than that in MSL1 system. The nitrification bacteria (amoA gene) were found mainly distributing in aeration stage, while denitrification bacteria (nirS, nirK) mainly distributed in the soil layer of anaerobic stage, which evidently explained the denitrification difference between two MSL systems in biological aspect.

• Key words：multi-soil-layering system  solid carbon source  low pollutant loading wastewater  enhanced nitrogen removal

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