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

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 m3·(m2·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 m3·(m2·d)−1)时对模拟污水厂尾水中$ {{rm{NH}}_4^ + }$-N、TN、TP和COD的去除率较高，但随着水力负荷的增大其去除率逐渐降低。3套垂直流人工湿地系统对$ {{rm{NO}}_3^{rm{ - }}}$-N的去除率均在高水力负荷(1 m3·(m2·d)−1)时较高，且随着水力负荷的变大，其去除率逐渐升高，但去除率的增长幅度变缓；实验证明，生物炭和活性炭改良基质能够提高湿地系统对$ { {rm{NH}}_4^ + }$-N、TN、TP和COD的去除效果，并且在低水力负荷时对$ {{rm{NH}}_4^ +} $-N、TN和COD的去除拥有更好的改良效果，而对TP去除的改良则在高水力负荷时优于在低水力负荷时。厌氧-异养反硝化菌能够提高湿地系统对$ {{rm{NH}}_4^ + }$-N、$ {{rm{NO}}_3^{rm{ - }}}$-N和TN的去除效果，并且在高水力负荷时对$ { {rm{NO}}_3^{rm{ - }}}$-N的改良效果优于低水力负荷，而在低水力负荷时对$ { {rm{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 m3·(m2·d)−1。

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

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 m3·(m2·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 $ {rm{NH}}_4^ + $-N, TN, TP, and COD in the tail water of simulated sewage plant at a low hydraulic loading of 0.25 m3·(m2·d)−1, and the removal rates progressively decreased with the increase of hydraulic loading. The removal rate of $ {rm{NO}}_3^{rm{ - }}$-N by these three improved VFCW systems was higher at the hydraulic loading of 1 m3·(m2·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 $ {rm{NH}}_4^ + $-N, TN, TP and COD in VFCW systems, even had a better removal effects for $ {rm{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 $ {rm{NH}}_4^ + $-N, $ {rm{NO}}_3^{rm{ - }}$-N and TN in VFCW system, and better improvements were achieved for $ {rm{NO}}_3^{rm{ - }}$-N removal occurred at higher hydraulic loadings, while for $ {rm{NH}}_4^ + $-N and TN removal at lower hydraulic loadings. Comprehensive consideration of the simultaneous removal of various pollutants, 0.5 m3·(m2·d)−1 was recommended as the optimal hydraulic loading for the three improved VFCW systems.