Water quality and change pattern of residual water in reservoir environmental dredging and plate and frame dewatering project

Abstract

湖泊、水库、河流污染后实施底泥环保疏浚工程的实例很多，但如何处理疏浚余水以及处理尾水排放应该执行什么样的控制标准，是一个没有解决的问题.针对这一问题，本文以溧阳市沙河水库环保疏浚以及配套的泥浆板框压滤脱水工程为例，研究了余水发生后的水质以及在各处理环节中的变化规律，基于这一规律探讨了疏浚尾水的排放标准.结果表明疏浚余水经过一级絮凝处理后大部分污染物可以去除，悬浮物、总氮、总磷、COD分别可去除73%~99%、21%~72%、69%~96%、32%~48%，但后续的生态处理并没有体现出明显的效果.通过处理后尾水基本上能够达到《污水综合排放标准》（GB 8978—1996）一级排放标准，如需进一步提升排放标准，尾水中的氨氮成为制约性指标.;There are many examples of environmental dredging applied on the polluted lakes, reservoirs, and rivers. However, the treatment of dredging residual water and the control standards of tailwater discharge have not been clearly defined yet. To address this issue, this paper takes the environmental dredging of the Shahe Reservoir and its supporting mud plate and frame filter press dewatering project in Liyang as an example, and studies the water quality after the occurrence of residual water and the changing pattern in each treatment process. Based on this pattern, the discharge standard of dredged tailwater is discussed. The results indicate that most of the pollutants in the dredged water can be removed after the first-level flocculation treatment. The removal rates of suspended solid, total nitrogen, total phosphorus and COD are 73% to 99%, 21% to 72%, 69% to 96% and 32% to 48% respectively, but the subsequent ecological treatment is not effective. Referring to the Integrated Wastewater Discharge Standard (GB 8978-1996), most of the treated tail water achieve the first level discharge standard. If the discharge standard needs to be further improved, the ammonia nitrogen in the tailwater would become a restrictive indicator.