水力负荷对改良型垂直流人工湿地降解模拟污水厂尾水效果的影响

Effect of hydraulic loading on the degradation of the simulated tail water from wastewater treatment plant by improved vertical flow constructed wetland

为确定改良型垂直流人工湿地降解模拟污水厂尾水的最佳水力负荷,采用生物炭和活性炭改良、微生物强化以及同时添加生物炭、活性炭和微生物改良强化的3套垂直流人工湿地系统,研究了其在3种水力负荷条件下(0.25、0.5和1 m^3·(m^2·d)^-1),对模拟污水厂尾水中污染物的去除效果。结果表明,3套垂直流人工湿地系统均在低水力负荷(0.25 m^3·(m^2·d)^-1)时对模拟污水厂尾水中NH^+4-N、TN、TP和COD的去除率较高,但随着水力负荷的增大其去除率逐渐降低。3套垂直流人工湿地系统对NO^-3-N的去除率均在高水力负荷(1 m^3·(m^2·d)^-1)时较高,且随着水力负荷的变大,其去除率逐渐升高,但去除率的增长幅度变缓;实验证明,生物炭和活性炭改良基质能够提高湿地系统对NH^+4-N、TN、TP和COD的去除效果,并且在低水力负荷时对NH^+4-N、TN和COD的去除拥有更好的改良效果,而对TP去除的改良则在高水力负荷时优于在低水力负荷时。厌氧-异养反硝化菌能够提高湿地系统对NH^+4-N、NO^-3-N和TN的去除效果,并且在高水力负荷时对NO^-3-N的改良效果优于低水力负荷,而在低水力负荷时对NH^+4-N和TN具有更好的改良效果。综合考虑多种污染物的去除效果,确定3套改良型垂直流人工湿地系统的最佳水力负荷为0.5 m^3·(m^2·d)^-1。

To study the optimal hydraulic loading of improved vertical flow constructed wetland(VFCW)degrading the simulated tail water in wastewater treatment plant,three improved VFCW systems were built with addition of biochar-activated carbon,microorganisms or biochar-activated carbon-microorganisms,respectively.The effects of different hydraulic loading conditions(0.25,0.5 and 1 m^3·(m^2·d)^-1)on the pollutants removal from the simulated tail water in wastewater treatment plant were investigated.Results showed that the three improved VFCW systems had high removal rates of NH^+4-N,TN,TP,and COD in the tail water of simulated sewage plant at a low hydraulic loading of 0.25 m^3·(m^2·d)^-1,and the removal rates progressively decreased with the increase of hydraulic loading.The removal rate of NO^-3-N by these three improved VFCW systems was higher at the hydraulic loading of 1 m^3·(m^2·d)^-1,and the removal rate increased with the increase of the hydraulic loading,while the increment of removal rate slowed down gradually.The experiment results showed that biochar-activated carbon modification could improve the removal efficiencies of NH^+4-N,TN,TP and COD in VFCW systems,even had a better removal effects for NH^+4-N,TN and COD at low hydraulic loadings,while higher TP removal occurred at higher hydraulic loadings.The presence of anaerobic-heterotrophic denitrifying bacteria could improve the removal effect of NH^+4-N,NO^-3-N and TN in VFCW system,and better improvements were achieved for NO^-3-N removal occurred at higher hydraulic loadings,while for NH^+4-N and TN removal at lower hydraulic loadings.Comprehensive consideration of the simultaneous removal of various pollutants,0.5 m^3·(m^2·d)^-1 was recommended as the optimal hydraulic loading for the three improved VFCW systems.