功能分区型人工湿地处理养殖废水厌氧消化液的性能

Performance of a Functional Zoning Constructed Wetland for the Treatment of Digested Swine Wastewater

针对养猪废水厌氧消化液高ρ(NH4+-N)的特点,构建了上层填充沸石强化硝化、下层填充砖渣强化反硝化的功能分区型人工湿地,考察其启动阶段运行性能、硝化区及反硝化区污染物去除性能.结果表明,湿地以间歇方式运行(饱和液位无变化),启动后NO3--N的产生速率为0.014 6 kg/(m3·d),湿地底部出水的ρ(NO3--N)平均值为14.94 mg/L,明显低于沸石层的21.77mg/L.CODCr主要在湿地上层硝化区被去除,平均去除率为64.82%.随着湿地启动,下层由于反硝化作用消耗的有机物增至56.67 mg/L.在进水期的前15 min,CODCr、NH4+-N、TP的去除率最大,NO3--N溶出量(以ρ计)最高,达42.30 mg/L.沸石层10、20和30 cm处硝化速率基本稳定,沸石层的Eh均在400 m V以上.与间歇方式相比,湿地以潮汐流方式(进水期与落干期时间比为1 h∶23 h)运行时,CODCr和TN去除率分别由78.45%和41.99%升至82.62%和53.41%.研究显示,功能分区型人工湿地通过上层硝化、下层反硝化方式可有效去除养殖废水厌氧消化液中的NH4+-N.

Anaerobically digested swine wastewater contains high concentrations of ammonia. A functional zoning constructed wetland,which contained a zeolite-filled nitrification zone and a brick-filled denitrification zone,was built to treat the wastewater. The performance of the constructed wetland during the start-up period,and the removal of pollutants in both the nitrification and denitrification zones were investigated. The results showed that nitrification of the batch flow（ i. e.,the saturated liquid level unchanged） constructed wetland was obvious,and the generated rate of NO3--N was 0. 0146 kg/（ m3·d） after 44 d operation. The average ρ（ NO3--N） in the denitrification zone was 14. 94 mg/L,which was lower than that in the nitrification zone（ 21. 77 mg/L）. CODCrwas mainly removed in the nitrification zone,and the average removal rate was 64. 82%. Also,the organic matters consumed by denitrification increased to 56. 67 mg/L with the maturation of denitrifiers. The removal rates of CODCr,NH4＋-N and TP were the highest in the initial 15 min of wastewater flowing,and the highest ρ（ NO3--N）（ 42. 30 mg/L） was also obtained in this period. The nitrification rate was stable at different heights of nitrification zone（ i. e.,10,20 and 30 cm）,and Ehof the nitrification zone was above 400 m V. Compared to the batch flow operation,the tidal flow operation（ feeding phase： draining phase = 1 h∶ 23 h） was better,and the removal rates of CODCrand TN were improved from 78. 45% and 41. 99% to 82. 62% and53. 41%, respectively. In conclusion, the functional zoning constructed wetland could remove NH4＋-N from the wastewater bynitrification at the top of the zeolite-filled zone and denitrification at the bottom of the brick-filled zone.