进水方式对生态碎石床去除生活污水中氮的影响

为提高生态碎石床对生活污水中氮的去除率,设计了空白床、芦苇床、水葱床、香蒲床4组生态碎石床,研究在连续进水(水力负荷7.5 cm∕d,水力停留时间1.8 d)和间歇进水(水力负荷7.5 cm∕d,水力停留时间5.4 d)2种进水方式下对生活污水中总氮(TN)、氨氮(NH4+-N)和硝氮(NO3--N)的去除效果。结果表明:不同生态碎石床在2种进水方式下对氮的去除率差异较大,连续进水时对TN、NH4+-N的去除率依次是香蒲床>水葱床>空白床>芦苇床,香蒲床对TN、NH4+-N去除率较高,分别为77.68%和81.33%;对NO3--N的去除率依次是空白床>芦苇床>香蒲床>水葱床,空白床去除率最好,为65.29%。间歇进水时对TN、NH4+-N的去除率依次是水葱床>芦苇床>香蒲床>空白床,水葱床对TN、NH4+-N去除率较高,分别为89.54%和91.79%;对NO3--N去除率依次是水葱床>香蒲床>空白床>芦苇床,水葱床去除率最佳,为46.43%。间歇进水有利于提高生态碎石床对TN和NH4+-N的去除率,其中芦苇床对TN去除率增加19.63%,对NH4+-N去除率增加14.76%,水葱床对TN去除率增加19.14%,对NH4+-N去除率增加18.60%。

Effects of inflow modes on sewage nitrogen removal by ecological gravel beds

In order to improve the nitrogen removal rate of residential sewage by ecological gravel beds, four kinds of constructed ecological gravel bed were designed, including Schoenoplectus tabernaemontani bed, Phragmites australis bed, Typha orientalis bed and blank bed without vegetation. The effects of two inflow modes, i.e. continuous inflow and intermittent inflow, on the removal of TN, NH4+-N, and NO3--N were studied. The hydraulic load (HL) was 7.5 cm∕d and the hydraulic retention time (HRT) was 1.8 d under the continuous inflow, while the HL was 7.5 cm∕d and the HRT was 5.4 d under the intermittent inflow. The results show that there exists great difference of the nitrogen removal efficiency between two inflow modes for different ecological gravel beds. The removal rates of TN and ammonia nitrogen under continuous inflow were in the order of Typha orientalis bed> Schoenoplectus tabernaemontani bed > blank bed > Phragmites australis bed, with the highest removal rates by Typha orientalis bed, which removal rate of TN and ammonia nitrogen were 77.68% and 81.33%, respectively; the removal rates of nitrate nitrogen were in the order of blank bed>Phragmites australis bed>Tyha orientalis bed>Schoenoplectus tabernaemontani bed, with thee highest removal rates by blank bed, which removal rate of nitrate nitrogen was 65.29%. The removal rates of TN and ammonia nitrogen under intermittent inflow were in the order of Schoenoplectus tabernaemontani bed > Phragmites australis bed > Typha orientalis bed> blank bed, and the effect of Schoenoplectus tabernaemontani bed was the best, which removal rate of TN and ammonia nitrogen were 89.54% and 91.79%, respectively; the removal rates of nitrate nitrogen were in the order of Schoenoplectus tabernaemontani bed>Typha orientalis bed>blank bed>Phragmites australis bed, the Schoenoplectus tabernaemontanid bed was the best with a removal rate of 46.43%. The removal efficiency of ammonia nitrogen and TN were better improved by intermittent inflow in plant systems. The removal rate of TN and ammonia nitrogen increased by 19.63% and 14.76% in Phragmites australis bed, and the removal rate of TN and ammonia nitrogen increased by 19.14% and 18.60% in Schoenoplectus tabernaemontani bed, respectively.