不同强化手段对生物滞留池脱氮除磷性能的影响

Effect of Different Enhanced Methods on Efficiency of Denitrification and Phosphorus Removal in Bioretention Cell

为了探究不同强化手段对生物滞留池脱氮除磷的影响,引入活性炭、导线、活性炭加导线和内加催化铁(Fe0/Fe2+)4种组合强化方式,探究生物滞留池对COD、NH+4-N、TN、TP的去除效果。实验结果表明,在厌氧区添加活性炭层可以有效提升系统的反硝化能力,总氮去除率提高8%~23%;好氧区与厌氧区之间增加导线可以促进系统的硝化能力,使出水氨氮浓度降低5%~10%;催化铁可以为反硝化提供电子供体,也能将NO-3-N还原为NH+4-N;添加活性炭层的强化组对磷的吸附能力明显高于未添加活性炭实验组,其中同时添加活性炭与催化铁实验组的效果最好,对总磷的去除率提高了10%~20%,且在运行期间(180 d)不释磷;氮磷负荷对出水水质有显著影响。低负荷(TN为30 mg/L、TP为2 mg/L)运行时,强化组对总氮和总磷的去除效果明显提高,出水COD与TP能够达到地表水Ⅳ类标准,TN与NH+4-N满足城镇污水排放一级A标准;高负荷(TN为60 mg/L、TP为4 mg/L)运行时,脱氮除磷效果波动明显,但降低氮磷负荷后仍能回到稳态,不同强化手段能较好地增加生物滞留池对于水质变化的适应能力,是小水量分散式污水处理的一种可行方案。

In order to explore the effects of different enhanced methods on denitrification and phosphorus removal in bioretention cell (BRC),four combined enhanced methods,namely addition of activated carbon,wire,activated carbon plus wire and catalytic iron,were introduced to explore their removal effects on COD,NH4+-N,TN and TP in BRC.The addition of activated carbon layer in the anaerobic zone could effectively improve the denitrification ability of the system,and the remova efficiency of TN increased by about 8%to 23%.Nitrification ability of the system could be promoted by adding wires between aerobic zone and anaerobic zone,and NH4+-N concentration in the effluen decreased by 5% to 10%.Catalytic iron (Fe0/Fe2+) could provide electron donor for denitrification and reduce NO3--N to NH4+-N.The phosphorus adsorption capacity of the enhanced group with activated carbon layer was significantly higher than that of the experimental group without activated carbon,among which the experimental group with activated carbon and catalytic iron had the best performance.The removal efficiency of total phosphorus increased by 10%to 20%,and phosphorus was not released during the operation period (180 days).The nitrogen and phosphorus load had a significant effect on the effluent quality.When the system was operated at low load (TN of 30 mg/L and TP of 2 mg/L),the removal of total nitrogen and total phosphorus was significantly improved in the enhanced group.COD and TP concentration in the effluent could meet classⅣstandard of surface water,and TN and NH4+-N could meet grade A standard of urban sewage discharge.When the system was operated at high load (TN of 60 mg/L and TP of 4 mg/L),the removal efficiencies of nitrogen and phosphorus fluctuated obviously.However,it could return to a steady state after reducing nitrogen and phosphorus load.Different enhanced methods can better increase the adaptability of BRC to water quality change,which is a feasible scheme for decentralized sewage treatment with low flow quantity.