日本琵琶湖污染源系统控制及其对我国湖泊治理的启示

琵琶湖富营养化全面有效的控制得益于对流域污染源的系统控制. 琵琶湖流域污染源系统控制包括通过立法与监管严格控制工厂与企业的污水排放、城镇污水管网与大型污水处理设施的高度覆盖、农业集落污水处理设施的全覆盖三部分,流域污水处理系统的全覆盖及高度处理技术的普及是其最为成功的经验之一. 琵琶湖流域城镇下水道普及率达86.4%,主要污染物——TN、TP及COD_Mn的去除率分别高达90.0%、98.7%及94.6%. 琵琶湖流域同时实施了净化槽普及、设置农业集落排水处理设施、初期雨水净化处理及农田循环灌溉等具有地方特色的面源治理对策. 通过综合治理,琵琶湖主要入湖污染负荷明显减少,与1985年相比,2012年COD_Mn点源污染负荷减少了76.8%,TN减少了45.5%,TP减少了65.6%. 与之比较,我国的湖泊治理存在的问题主要包括有针对性的地方排放标准的缺失及执法力度的不足、城镇污水深度处理及运营管理技术上的差距、面源污染对策的严重不足. 

Integrated Control of Pollution Sources in Lake Biwa Basin, Japan and Its Successful Experience in Lake Eutrophication Management

The key goal of lake eutrophication management is control of pollution source in its drainage basin. Comprehensive and effective governance of Lake Biwa eutrophication benefits from the systematic control of the pollution sources in the lake basin. It can be described in three aspects:1) control of sewage discharge of factories and enterprises by legislation; 2) high degree coverage of urban sewage collection network and large centralized sewage treatment facilities; and, 3) complete coverage of the sewage treatment facilities in agricultural areas. The most successful practice is the basin-level wastewater collection and sewage treatment system with advanced technologies. The sewage pipeline network now collects 86.4% of urban pollution in the watershed, and the removal rates of TN, TP, and COD_Mn are 90.0%, 98.7% and 94.6%, respectively. Pollution control for non-point sources in the watershed consists of domestic wastewater treatment tank, agricultural wastewater treatment facilities, rainwater purification treatment facilities and farmland re-irrigation facilities. Through the systematic management of pollution sources in the watershed, the pollution loading into the lake is significantly reduced. Compared with those in 1985, COD_Mn, TN and TP load of point pollution in 2012 were reduced by 76.8%, 45.5% and 65.6%, respectively. Comparing national and local wastewater drainage standards, large centralized sewage treatment facilities and non-point source pollution control technology between Japan and China, potential directions in eutrophication management for Chinese lakes are highlighted.