On December 29, 2023, the National Development and Reform Commission, the Ministry of Housing and Urban-Rural Development, and the Ministry of Ecology and Environment jointly issued the "Implementation Opinions on Promoting the Synergies of Pollution and Carbon Reduction in Sewage Treatment" (hereinafter referred to as the "Implementation Opinions").

The "Implementation Opinions" pointed out that China's ecological civilization construction has entered a critical period with carbon reduction as the key strategic direction. Sewage treatment is not only an important starting point to in-depth fight against pollution prevention and control, but also an important area to promote greenhouse gas emission reduction. By 2025, China will build 100 green and low-carbon benchmark plants for wastewater treatment with efficient recycling of energy and resources.

According to expert analysis, sewage treatment should achieve synergistic effect of reducing pollution and carbon through its own energy saving, improving treatment efficiency and increasing carbon sink. At the same time, policy support and scientific and technological support for the industry are also essential.

Making up for weaknesses and reducing pollution and carbon have become key topics

"Up to now, China has built nearly 5,000 sewage treatment plants in cities and counties, with a total treatment capacity of more than 250 million cubic meters per day, and the urban sewage treatment rate exceeds 98 percent." The "Implementation Opinions" pointed out that in recent years, China's sewage collection and treatment facilities have been continuously improved, but the low sewage collection efficiency, more greenhouse gas emissions in the sewage treatment process, and the low level of energy resource recycling and utilization still exist.

According to the actual situation of China's sewage treatment industry, the "Implementation Opinions" deployed key tasks such as strengthening water saving at the source and improving the efficiency of sewage collection. In addition, strengthening the energy saving and carbon reduction of sewage treatment is also the key.

Between the grid, the sedimentation tank, and the biochemical tank, the sewage flows in and out between various equipment. Industry insiders pointed out that as an enterprise dealing with all kinds of pollutants in domestic sewage, although the sewage treatment plant is responsible for the green mission of improving the effluent water quality standards, reducing black and smelly water bodies and eutrophication and other water environmental problems, the sewage treatment mode of "energy consumption for water quality" makes the equipment inevitably produce certain carbon emissions during operation. There is also a risk of transferring water pollution to air pollution.

Relevant data show that the carbon emissions of the sewage treatment industry account for about 1% of the total emissions of the whole society, mainly from the organic pollutants in the water after degradation, the release of carbon dioxide, methane and nitrous oxide and other greenhouse gases. In addition to the above direct emissions, the electricity and thermal energy consumption required for the operation of sewage treatment plants, as well as the production and transportation of chemicals used for sewage treatment, will also indirectly generate carbon emissions.

In recent years, with the increase of sewage treatment capacity brought by the development of urbanization, upgrading and upgrading has become a consistent action of many sewage treatment plants, and the resulting carbon emissions have also increased.

The reporter found that in June 2023, an administrative penalty decision issued by the Beijing Municipal Bureau of Ecological Environment showed that a local company with sewage treatment and water reuse treatment as its main business was fined more than 2 million yuan for exceeding the quota to emit more than 4,000 tons of carbon dioxide.

Carbon reduction has become a subject that the sewage treatment industry must face. The "Implementation Opinions" put the synergies of pollution reduction and carbon reduction in a prominent position.

Energy saving, efficiency improvement, carbon sinks, multiple ways to make carbon emission reduction

How should the sewage treatment industry move towards green and low-carbon development?

The "Implementation Opinions" pointed out that by saving energy and reducing consumption, improving treatment efficiency or increasing carbon sink, the carbon emission reduction and carbon emissions of sewage treatment plants offset each other.

Yuan Shuai, executive vice president of the China Urban Development Research Institute of Agricultural and Cultural Tourism Industry Revitalization Research Institute, told this reporter that the sewage treatment industry should improve the efficiency of sewage treatment, reduce the discharge of harmful substances in sewage, and reduce energy consumption and carbon emissions; Second, we should promote the resource utilization of sewage, recycle the treated sewage as water resources, reduce the demand for fresh water resources, and reduce the carbon emission of water treatment. Third, we should strengthen energy conservation and carbon reduction and carbon footprint management, comprehensively monitor and manage energy consumption and carbon emissions in the sewage treatment process, and take targeted measures to reduce energy consumption and carbon emissions.

"The difficulty is how to balance the relationship between sewage treatment, carbon reduction and energy saving, and achieve synergies among the three." In addition, the layout of the sewage treatment plant also needs to consider the terrain, climate, population density and other factors, reasonable planning of sewage collection and treatment system, improve the efficiency of sewage collection and treatment." Yuan Shuai said.

In terms of energy saving and carbon reduction transformation, the "Implementation Opinions" proposed to promote the selection of energy-efficient motors, fans, pumps, lighting appliances and other general product equipment, combined with the upgrading of the plant area, to speed up the elimination of old and inefficient key energy use equipment. Promote the construction of a smart water management system, carry out intelligent regulation and optimization of the whole process, and achieve accurate aeration and reflux control, digital metering and accurate dosing.

The reporter previously noted in an interview that more and more sewage treatment plants have increased their investment in intelligent equipment in their daily operations, and some sewage treatment plants have realized the full coverage of big data production and operation dispatching command system for operational projects.

It is worth mentioning that the "Implementation Opinions" proposed that cities with scarce land resources can build all-underground or semi-underground sewage treatment plants, encourage the reasonable use of above-ground space through the construction of parks and green activity sites, and improve the regional environmental quality and the carbon sink capacity of urban ecosystems.

In Yinchuan City, Ningxia Hui Autonomous Region, an "Internet red" recycled water plant has "dropped" this idea to the ground. The recycled water plant adopts the semi-underground building form, and the top of the sewage treatment box is designed as an open ecological landscape park, so that the public entertainment and the operation and production of the water plant can not interfere with each other. Zhou Wenbin, director of the recycled water plant, told reporters that more than 100,000 tons of domestic sewage is collected here every day, and the treated water reaches the surface quasi class IV, which meets the reuse standard, and can be used nearby for urban afforestation irrigation, river and lake replenishment, municipal utility, etc.

More than that, public reports show that in Wuhan, Hubei, Chengdu, Sichuan, Ningbo, Zhejiang, Dali, Yunnan... Such garden-style reclaimed water plants are found in many provinces and cities in our country. The sewage treatment industry is actively solving the problem of synergistic efficiency of pollution reduction and carbon reduction, in order to achieve a win-win situation of water resource recycling and urban ecological carbon sink enhancement.

New opportunities at the policy and technical levels

China's ecological civilization construction has entered a critical period of focusing on the strategic direction of carbon reduction and promoting the synergistic efficiency of pollution reduction and carbon reduction. This also points out the direction for China's sewage treatment industry in the coming period.

In June 2022, the "Implementation Plan for Synergistic Efficiency of Pollution Reduction and Carbon Reduction" issued by the Ministry of Ecology and Environment put forward requirements for optimizing governance objectives, governance processes and technical routes in many fields such as water, atmosphere, soil, solid waste and greenhouse gases. The "implementation Opinions" mentioned that by 2025, 100 green and low-carbon benchmark plants for wastewater treatment with efficient recycling of energy and resources should be built. This specific goal will bring new development opportunities for the sewage treatment industry.

"In terms of policy, the state will increase policy support and financial investment in the sewage treatment industry, encourage the sewage treatment industry to carry out technological innovation and research and development, and promote technological progress and industrial upgrading of the industry." In addition, there are market opportunities. With the acceleration of urbanization and the improvement of people's awareness of environmental protection, the market demand for sewage treatment will further increase." Yuan Shuai pointed out.

The "implementation Opinions" pointed out that the financial support for sewage treatment and carbon reduction upgrading projects should be increased, and eligible projects should be included in the scope of local government special bond support, the issuance of real estate investment trusts, the application for green credit or financing through green bonds. At the same time, we will implement preferential tax policies in areas such as environmental protection, energy conservation and water saving.

The prosperity of policies and markets will also further promote the innovation and improvement of sewage treatment technology to achieve high efficiency and low energy consumption. Zhang Xinyuan, head of research at the Co-Found think tank, a domestic consulting institution, told reporters that the application of renewable energy in the sewage treatment process should be increased, such as solar energy, wind energy, etc., to achieve energy self-sufficiency or significantly reduce energy consumption. Implement carbon emission control, such as the use of anaerobic digestion technology in the sewage treatment process to improve the efficiency of sludge treatment and reduce carbon emissions.

The "Implementation Opinions" also proposed to increase scientific and technological support. We will carry out research on key green and low-carbon technologies for sewage treatment, focusing on breakthroughs in key common technologies such as the treatment and recycling of high-concentration organic wastewater and high-salt wastewater, high-performance membrane materials, environmentally friendly pharmaceuticals, greenhouse gas control, intelligent monitoring and optimal control, and promote the integration of digital technologies such as big data, artificial intelligence, and digital twins with sewage treatment processes.

文章来源：中国环境

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