What is even more exaggerated is that some time ago, Shandong proposed that the urban sewage treatment plants in the province should meet the quasi-IV emission standard. Then this move was successfully spread to other provinces. Recently, Jiangsu's "Discharge Standard of Pollutants for Urban Sewage Treatment Plants" (draft for approval) was published, in which many conventional indicators of discharge standard A reached quasi-IV water standard except TN. Sure enough, the local government has never let the sewage treatment plant down in the matter of "standards".
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The discharge standard of urban sewage in Jiangsu Province has been officially announced, and a new round of upgrading has come!
Recently, the local standard of Jiangsu Province, Pollutant Discharge Standard for Urban Sewage Treatment Plants (Draft for Approval), was released. Among them, the standard requires that for the newly-built urban sewage treatment plant, if the sewage outlet is located in a key protected area and the total design scale is greater than or equal to 5000m3/d, and the sewage outlet is located in a general area and the total design scale is greater than or equal to 10000m3/d, the A standard shall be implemented; Other implementation standards B.
The existing urban sewage treatment plant, the sewage outlet is located in key protected areas, the implementation of standard B; If the sewage outlet in the general area is located in Taihu Lake area, the C standard shall be implemented; Except for Taihu Lake area, the sewage outlet is located in the general area, and if the total design scale is greater than or equal to 3000 m3/d, the C standard shall be implemented, and if the total design scale is less than 3000m3/d, the D standard shall be implemented.
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Some time ago, Shandong Province made clear the requirements of Class IV emission limits for urban sewage treatment plants in the province, in which the total nitrogen was controlled at10-12 mg/L. During the Tenth Five-Year Plan period, the new urban sewage treatment capacity in the province was 2 million tons/day, and 60% of urban sewage treatment plants were upgraded, and the main indicators of effluent quality reached the quasi-IV emission standard.
When it comes to quasi-IV emission standards, Beijing naturally bears the brunt. On 20 12, Beijing local standard "Discharge Standard of Water Pollutants for Urban Sewage Treatment Plants" (DB11/890—2065438+02) was issued. The standard B in this landmark has reached the quasi-IV emission standard, while the standard A has almost reached the quasi-III emission standard. Also from the second time, other provinces began to match the quasi-IV emission standards.
After the standardization of standards in various places, it has brought a new problem, that is, blind bidding. However, behind the bidding, the original process was reinvented, more expensive processes were adopted, and more chemicals were added, which greatly increased energy consumption and operating costs. It may also crowd out the investment in the weak links of urban sewage treatment system such as pipe network and sludge.
Therefore, in order to avoid the vicious circle of blind bidding, in July this year, the "Implementation Plan for Deepening Urban Black and Odor Water Treatment" jointly issued by the Ministry of Ecology and Environment, the Ministry of Water Resources, the Ministry of Housing and Urban-Rural Development and the National Development and Reform Commission was formally formed. Among them, it is explicitly required that cities with the influent biochemical oxygen demand concentration of existing sewage treatment plants below 100mg/L should formulate systematic remediation plans, and specify measures such as pipeline network inspection and transformation, sewage diversion, industrial wastewater and engineering drainage, and traceability law enforcement. It is not allowed to blindly improve the effluent standard of sewage treatment plants or newly expand sewage treatment plants.
So, what discharge standards should sewage treatment plants implement to be reasonable?
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At the beginning of this year, the Ministry of Ecology and Environment issued the Letter for Soliciting Opinions on the Revised Draft of Pollutant Discharge Standard for Urban Sewage Treatment Plants (GB 189 18-2002). Among them, when explaining why the standard was revised, it was pointed out that the provisions of the current standard on taking mixed samples and measuring the daily average value of all water pollutants were obviously insufficient in supporting accurate, scientific and legal pollution control and needed to be revised and improved urgently.
At the same time, because many sewage treatment plants only stay on the indicators when implementing the standards, they have not fully considered the quality and quantity of regional sewage and the environmental capacity of receiving water bodies. For high-standard sewage treatment plants that have been built or are under construction, the real focus should be on COD, nitrogen and phosphorus, and high-emission standard technologies including pretreatment, enhanced secondary treatment and post-treatment should be adopted.
According to relevant research, a 40,000-ton sewage treatment plant in a certain area needs to invest more than 800 million yuan to be built, because the sewage treatment process is very complicated because of the excessive discharge standard of surface water III and the underground sewage treatment plant, but the investment "cost performance" is too low, the local economic development level is not high, and the financial resources are very limited. If the ground sewage treatment plant is built according to Class A standard, 80 million construction funds may be enough.
Therefore, it is the right way for local governments to improve the sewage treatment rate and the compliance rate under the current standards, and blind bidding is simply nonsense.
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The real "short board" of sewage plants is actually the pipe network. The total amount of pipe network is not high enough, resulting in low centralized sewage collection rate, and some sewage still has the risk of overflowing into the river. Therefore, for sewage treatment plants, it is necessary to balance the sewage treatment and discharge standards with the needs of pipe network construction, and give priority to the limited funds for the construction and maintenance of drainage pipe network.
Of course, standards should still return to the original intention of taking standards as standards, rather than using other people's standards.