正交试验优化垂直潜流人工湿地实现短程硝化

Orthogonal experiment to optimize vertical subsurface flow constructed wetland for short-cut nitrification

采用垂直潜流人工湿地(VSFCW)处理生活污水并实现短程硝化.将温度、pH值、溶解氧(DO)、HRT分别控制在:(30±2)℃、(8.4±0.2)、(1.5±0.2)mg/L、12h的条件下,COD去除率与NH4+-N去除率(ARE),亚硝酸盐积累率(NAR)分别为73.14%、98.51%、65.18%.向VSFCW中投加羟胺(NH2OH),来进一步提高NAR.通过设计4因素5水平正交试验获取NH2OH浓度、DO、温度、pH值的最佳控制条件.在本试验中,方差分析结果表明:NH2OH浓度和温度对NAR的影响极其显著(P≤0.01).DO与pH值对NAR的影响不显著(P>0.05).对方差分析结果进行优化验证,当投加1.0mg/L的NH2OH时,即使温度从30℃降低至23℃,NAR仍可达到89.15%.COD去除率与ARE为75.67%与88.76%.Nitrosomonas的丰度从1.62%增长至4.06%,Nitrospira的丰度从1.65%降至0.95%.

Vertical subsurface flow constructed wetland(VSFCW) was used to treat domestic wastewater and short-cut nitrification was achieved.When the temperature, pH value, dissolved oxygen(DO), and hydraulic retention time(HRT) were maintained at(30±2) ℃,(8.4±0.2),(1.5±0.2) mg/L, and 12h, respectively.The removal efficiency of COD and ammonia removal efficiency(ARE)were 73.14%, 98.15%, respectively.However, nitrite accumulation rate(NAR) was 65.18%.The NAR can be improved further by adding hydroxylamine(NH2OH) to VSFCW.A 4-factor, 5-level orthogonal experiment was designed to determine the optimal control conditions of the NH2OH concentration, DO, temperature, and pH value.In this study, the analysis of variance(ANOVA)results revealed that the effects of NH2OH concentration and temperature on NAR were extremely significant(P≤0.01).DO and pH value had no significant effect on NAR(P>0.05).Even if the temperature was dropped from 30 ℃ to 23 ℃, the NAR could reach 89.15% by adding 1.0mg/L NH2OH.And the removal efficiency of COD and ARE were 75.67% and 88.76%, respectively.The abundance of Nitrosomonas increased from 1.62 % to 4.06 %, and the abundance of Nitrospira declined from 1.65 % to 0.95 %.