低C/N(<3)条件下SNEDPR系统启动及其脱氮除磷特性研究

为了解同步硝化内源反硝化除磷（SNEDPR）系统处理低C/N（<3）污水的脱氮除磷特性，采用厌氧/低氧（溶解氧0.5~1.0mg/L）运行的SBR反应器，以低碳城市污水为处理对象，考察了C/N对SNEDPR启动、脱氮除磷性能优化与菌群结构变化的影响.结果表明：进水C/N由4.3提高至5.15时，系统脱氮除磷性能均逐渐增强，系统总氮（TN）和PO₄^3--P去除率最高达89.3%和90.6%；降低进水C/N <3后，系统脱氮、除磷性能均呈现先降低后逐渐升高的趋势，但低C/N对PAOs（聚磷菌）除磷性能的影响高于其对反硝化聚糖菌（DGAOs）内源反硝化脱氮性能的影响，表现为TN和PO₄^3--P去除率分别先降低至21.4%和3.4%后逐渐升高至92.9%和94.1%.系统稳定运行阶段，单位COD平均释磷量和SNED率达437.1mgP/gCOD和89.1%，出水NH₄⁺-N、NO_x^--N和PO₄^3--P浓度平均为0，4.4，0.2mg/L.经136d的运行，系统内PAOs，GAOs，AOB（氨氧化菌）和NOB（亚硝酸盐氧化菌）分别占全菌的（16±3）%，（8±3）%，（7±3）%和（3±1）%，其保证了系统除磷、硝化和反硝化脱氮性能.此外，系统好氧段存在同步短程硝化内源反硝化，是实现低C/N（<3）污水高效脱氮除磷的原因.

The nutrient removal characteristic of SNEDPR system during start-up and steady operation phases treating low C/N (<3) sewage

This study focused on the nitrogen (N) and phosphorus (P) removal characteristics in simultaneous nitrification-endogenous denitrification and phosphorus removal (SNEDPR) system treating low carbon/nitrogen (C/N) ratio (<3) wastewater. In order to achieve an efficient nutrient removal, an extended anaerobic/low aerobic (dissolved oxygen:0.5~1.0mg/L) sequencing batch reactor (SBR) fed with municipal sewage was started up and optimized by regulating the influent C/N ratio. The population dynamics of functional microorganisms were also analyzed. Results indicated that when the influent C/N ratio raised from 4.3 to 5.15, the N and P removal performance of the system became better with total nitrogen (TN) and PO₄^3--P removal efficiencies up to 89.3% and 90.6%, respectively; with C/N ratio reduced to <3, the nutrient removal performance decreased firstly and then increased in the following operation. However, the effect of low C/N on the phosphorus removal performance of PAOs (phosphorous accumulating organisms) was higher than the endogenous denitrification capability of DGAOs (denitrifying glycogen accumulating organisms), showed as the TN and PO₄^3--P removal efficiency reduced to 21.4% and 3.4% firstly, and lately increased to 92.9% and 94.1% gradually. In the stable phase of the system, the average phosphorus release per COD and SNED efficiency reached to 437.1mg/L and 89.1% respectively, with the average effluent concentration of NH₄⁺-N, NO_x^--N and PO₄^3--P was 0, 4.4, and 0.2mg/L, respectively. After 136-day operation, PAOs, GAO, AOB (ammonia oxidizing bacteria) and NOB(nitrite oxidizing bacteria) accounted for 16%±3%, 8%±3%, 7%±3% and 3%±1% of total biomass, respectively, which ensured the P uptake, nitrification and denitrification. Additionally, the occurrence of simultaneous partial nitrification-endogenous denitrification at the low aerobic stage of the system interpreted the efficient nutrient removal from low C/N (<3) wastewater.