农村汇水河浜生态修复组合工程处理效果分析

Removal efficiency of pollutants in the rural catchment branch by the combined engineering of ecological restoration

为有效削减农村集中居住区汇水河浜的污染物,在常州市武进区前黄镇运村村新运小桥浜东北侧次级支浜构建“前置库-湿地塘-生态沟”的生态修复组合工程,并沿水流方向采集水样(平枯水期7次、丰水期7次),监测主要水质指标,包括水温、pH、溶解氧(DO)、总氮(TN)、氨氮(NH_(4)^(+)-N)、硝氮(NO_(3)^(-)-N)、总磷(TP)、磷酸盐(PO_(4)^(3-)-P)、化学需氧量(COD)和悬浮物(SS),计算各污染物的沿程总削减率,分析各工艺段的污染通量,估算组合工程对于该次级支浜污染负荷的年削减量。结果表明:在平枯水期,组合工程主要依靠物理沉降、透水坝拦截等作用削减颗粒态污染物;在丰水期,组合工程主要依靠植物吸收、微生物降解等作用削减溶解态污染物。生活污水和分散菜地对于TN、TP污染负荷的贡献较大;生活污水对COD污染负荷的贡献最大。次级支浜水体氮素中NO_(3)^(-)-N含量较高,磷素中颗粒态磷(PP)含量较高。组合工程对次级支浜陆源污染中TN、TP和COD污染负荷的年削减量分别为166.23、20.07、502.66 kg·a^(-1)。研究表明,生态修复组合工程能够削减部分污染负荷,今后仍须加强来自生产、生活的陆源污染拦截,以及汇入新运小桥浜之后的水体原位净化。

To reduce the pollutants in a catchment branch in a rural residential area,a combined engineering project of ecological restoration consisting of a pre-reservoir,wetland pond,and ecological ditch was constructed in the secondary branch on the northeast of Xinyunxiaoqiaobang Branch in Yuncun Village,Qianhuang Town,Changzhou City.Water samples were collected 7 times in the regular and dry seasons and 7 times in the flood season.The physical and chemical indexes of water samples,including water temperature,pH,dissolved oxygen(DO),total nitrogen(TN),ammonia nitrogen(NH_(4)^(+)-N),nitrate nitrogen(NO_(3)^(-)-N),total phosphorous(TP),phosphate(PO_(4)^(3-)-P),chemical oxygen demand(COD),and suspended solids(SS),were monitored to analyze the total removal rates of pollutants,assess pollutant flux of the three process sections,and estimate the pollution load reduction by the engineering.The results showed that in the regular and dry seasons,physical settlement and permeable dam interception primarily removed the particulate pollutants in water,while in the flood season,plant absorption and microbial degradation removed the dissolved pollutants from the water.The pollution loads of TN and TP were mainly due to rural domestic sewage and scattered vegetable fields.In contrast,the pollution loads of COD mainly came from rural domestic sewage.In the secondary branch water,the proportion of NO_(3)^(-)-N was higher than NH+4-N in nitrogen,and the proportion of particulate phosphorus(PP)was higher than PO^(3-)_(4)-P in phosphorus.The combined engineering annually reduced the TN,TP,and COD from land-based sources by approximately 166.23,20.07 kg·a^(-1) and 502.66 kg·a^(-1),respectively.Even though the combined engineering of ecological restoration reduced the pollutant load partially,the interception of terrigenous pollutants from production and life and in-situ water purification in the Xinyunxiaoqiaobang Branch should be enhanced.