Seven Key Revision Points of the “Emission Standards for Pollutants from Urban Sewage Treatment Plants” (Draft for Comment)

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Compared with the current \"Emission Standards for Pollutants from Urban Sewage Treatment Plants,\" the draft for comment incorporates the following main changes: 1. The emission limits for the basic control pollutants have eliminated the three-level emission standards； The existing secondary standards have been tightened, primarily in terms of certain indicators such as COD and ammonia nitrogen ； A new category has been added: “areas where the density of land development is already high, the environmental carrying capacity is beginning to decline, or where the environmental capacity is limited and the ecological environment is fragile, making them prone to serious environmental pollution problems that require special protective measures”, along with special emission limits ； Among them, grades A and B remain basically unchanged. 2. The basic control items have been increased, from 12 to 21, mainly including toxic and harmful substances such as total mercury, total chromium, and hexavalent chromium. 3. The scope of application has been adjusted, with regulations established regarding the pollutant emissions of enterprises or institutions that provide wastewater treatment services to two or more polluting entities (except those in the same industry category). 4. The requirements for hierarchical control of air pollutant emissions have been removed. 5. The list of control items for setting emission limits was expanded, rising from 43 to 82 items. 6. The standard limits for sludge stabilization and harmless treatment have been adjusted, and the requirements for hierarchical control of air pollutant emissions have been removed. 7. A new category has been added: “areas where the density of land development is already high, the environmental carrying capacity is beginning to decline, or where the environmental capacity is limited and the ecological environment is fragile, making them prone to serious environmental pollution problems that require special protective measures”, along with specific emission limits ； The special concentration limit is nearly twice as strict as that for Class A; it is difficult for existing wastewater treatment plants to meet this limit, and it is also challenging for some biochemical wastewater treatment plants to carry out technical upgrades. Therefore, more advanced wastewater treatment processes and technologies need to be developed, or physicochemical methods must be employed.