Three lakes and two lakes, thousands of sails wave after wave. Yixing City, Jiangsu Province, located on the west bank of Lake Taihu, is a prestigious "hometown of environmental protection", where the first urban sewage resource concept plant in China is located. Recently, the reporter followed the "Yangtze River Protection Research Tour" interview group from Yixing city to the north for about half an hour, and saw a very design "clover" shaped building from afar, which was "bright" under the afternoon sun.
The construction of China's urban sewage treatment concept plant is a major industry innovation project initiated by well-known experts in the domestic environmental field, aiming to integrate cutting-edge innovative design and leading technologies in the global perspective with the concept of green development, and achieve the four goals of "water quality sustainability, energy recovery, resource recycling and environmental friendliness". In October 2021, the Yixing Urban Sewage Resources Concept Plant (hereinafter referred to as the concept factory), co-participated by Three Gorges Group, was first completed and put into operation, which subverted the traditional form of sewage treatment plants and innovatively adopted the "trinity" form of water purification center, organic matter collaborative treatment center and production-oriented R&D center, becoming a model of new environmental infrastructure.
"'Clover' is not only the shape of the building space, but also the functional composition, one leaf is a water resource ring with the goal of high-quality effluent, one leaf is an energy and resource ring with the goal of resource recycling, and the other leaf is a new function ring to meet the public's needs for a better life and ecology." With the vivid introduction of the staff, the reporter wandered in the concept factory and felt the magic of sewage "turning into clear".
"Sustainable water" brews coffee and beer, and advanced treatment technology realizes water quality sustainability
"Good water does not ask the source." Walking into the pool café in the center of the concept factory, the slogan inlaid on the wall is very eye-catching. On the bar, bottles of "Water X" and freshly brewed coffee stood.
"This is our factory's 'specialty', welcome to taste it." Zhang Yifei, the head of the concept factory, unscrewed a bottle of "sustainable water" to drink, and enthusiastically introduced it to the visiting reporters. After everyone tasted them one by one, Zhang Yifei threw out the long-laid "Easter eggs" - these "good waters" came from the sewage treated by the concept factory.
Water purification is the basic function of sewage treatment plants. The special feature of the concept plant is that water contaminants can be removed with short process limits. About 2,<> tons of domestic sewage per day enters the water purification center, and after primary sedimentation fermentation, advanced oxidation coupling and other technical treatment, the effluent can reach the surface class IV water standard, and is directly discharged into the nearby river, flowing into Yixing's Tuangui and Donggui to Taihu Lake.
Following the water purification line of the concept factory, the reporter came to the water outlet. I saw the gurgling clear stream, which continuously flowed into the Yunai River that passed around the factory, because the cleanliness was higher, and even formed a clear boundary when the factory water and the river merged.
"The sewage treatment part has achieved extreme nitrogen and phosphorus removal, and its cost performance is significantly better than the current domestic sewage treatment plant." Zhang Yifei said that traditional sewage treatment plants usually use activated sludge methods and other processes, which mainly remove organic matter and some nutrients such as nitrogen and phosphorus in sewage, and the removal effect of refractory substances such as emerging pollutants is poor. The concept plant adopts advanced and efficient loading clarification, autotrophic denitrification membrane bioreactor method, advanced oxidation and other processes, which can effectively remove organic matter, nutrients such as nitrogen and phosphorus in sewage, and refractory substances such as emerging pollutants, and improve the quality and stability of effluent. With the blessing of advanced technologies such as high-efficiency limit nitrogen removal, the sewage treatment effect can achieve a total nitrogen content of less than 3mg per liter of water, a positive phosphate content of less than 0.1mg, and a removal rate of 80% of emerging pollutants.
In terms of water quality sustainability, the effluent of the concept factory can ensure the safety of water quality of Taihu Lake, and through the use of international advanced technology and equipment, part of the effluent will come to the ultimate water purification unit for treatment, and the indicators can reach the national standard of drinking water after testing, bringing about the scientific and technological experience of sewage fundamentally regeneration. "Our 'perpetual water' can be drunk directly, can be used to brew coffee, and when the weather is a little warmer, we can also brew beer." Zhang Yifei said confidently.
In the production R&D center of the concept factory, the world's leading wastewater treatment technology and scenario application are displayed in real time. As soon as the reporter entered the door, he noticed a blue-and-white "container". Li Qi, member of the expert committee of the China Urban Sewage Treatment Concept Plant and professor of the School of Environmental and Civil Engineering of Jiangnan University, introduced that this is a device that is undergoing pilot testing. "From basic research to technology transformation, it is very important to carry out pilot tests. Because the concept factory uses a lot of new processes, we need to study and test to obtain the corresponding technical parameters, and we will also do some destructive or reactive tests, such as a particularly bad water in winter, or a sudden power outage. Li Ji said that after the small-scale test gradually reaches the maturity of the process, large-scale engineering tests can be carried out through the R&D center's 3 2-ton and <> <>,<>-ton test lines until it is promoted to the market.
Sludge is "transformed" into nutrient soil, biogas is used for power generation in the plant, and waste is turned into treasure to promote resource recycling
On a booth called "Pioneer House" in the factory, products such as flowers, green plants, universal nutrient soil, and organic fertilizer are on display. The logo printed on the outer packaging reminds reporters that this is another product "produced" by the concept factory.
"We process organic waste such as toothpaste-like Taihu cyanobacteria mud, straw from agricultural and forestry waste, greening garbage, fruit and vegetable waste, livestock and poultry manure, and sludge from domestic sewage into nutrient soil through high-dry anaerobic fermentation and aerobic composting process, and put it on the market after passing the inspection, and sell it in online stores." Zhang Yifei picked up a bag of Thai fragrant rice cultivated with organic fertilizer from the concept factory and showed the reporter the quality of the product.
According to reports, the organic matter collaborative treatment center set up by the concept factory can process about 100 tons of sludge, cyanobacteria, livestock and poultry manure and straw per day, and the current processing capacity is about 40 tons. The biogas produced by anaerobic digestion of these organic waste is used in cogeneration, and the electricity and heat generated can achieve energy self-sufficiency in the plant (energy self-sufficiency rate of more than 60%). The biogas liquid flows back to the water purification center for reprocessing, and the biogas residue is processed into soil and fertilizer products, and melons, fruits and vegetables are planted in the experimental field in the factory area, without secondary pollution and at the same time to realize the recycling of resources.
What are the practical considerations behind increasing investment and turning waste into treasure? Zhang Yifei explained that the sewage treatment industry belongs to the "big energy consumers", especially the demand for electricity, and its electricity consumption accounts for a large proportion of the total electricity consumption of the whole society. Traditional sewage treatment plants lack the awareness and technology of resource recycling, and often directly landfill or incinerate sludge, and the energy contained in organic matter in sewage is wasted.
In addition, sewage treatment requires a large amount of fuel and chemicals, which indirectly emits a large amount of greenhouse gases, and the treatment process itself directly emits greenhouse gases. For example, Li Ji said, for a long time, most domestic sewage has been treated using aerobic activated sludge method, that is, under the combined action of oxygen and bacteria, pollutants are oxidized off. However, the activated sludge method consumes huge amounts of energy and releases a carbon footprint (i.e. the total amount of carbon dioxide and other greenhouse gases produced, usually expressed in tons of carbon dioxide); At the same time, the process produces a large amount of wet sludge, which also consumes a lot of energy to dry, dispose of or incinerate.
Unlike conventional wastewater treatment plants, the concept plant uses an anaerobic process to anaerobically digest sludge to "recover" energy. "Our DANAS dry anaerobic reactor technology is an anaerobic digestion technology specializing in the treatment of organic waste waste, which has the characteristics of high feed solid content, large biogas production, anti-impurities, no sedimentation, high efficiency, etc., and has the title of 'big stomach king'." Li Ji said that the anaerobic microorganisms cultivated by the reactor convert organic matter into biogas, which can be used for power generation and purification into natural gas, and realize the stabilization and resource treatment of organic solid waste, which has the characteristics of low carbon and environmental protection.
"Several countries around the world have published carbon neutral technology roadmaps for wastewater treatment plants, which is also the goal of the concept plant. We hope to play a certain exemplary role in resource recovery and energy recycling, so that everyone can see that sewage treatment plants can also be green and low-carbon. Zhang Yifei said that by integrating advanced technologies for pollution reduction and carbon reduction, the concept plant will expand the sewage treatment plant from the basic function of pollutant reduction to various application scenarios such as urban energy plants, water source factories, fertilizer factories, etc., which will enable the whole society to experience the concept of "sewage is a resource, and sewage plants are resource factories".
Integrate ecological life and production to create a new type of environmental infrastructure that is mutually beneficial and symbiotic
There is no dirty environment, no smell of sewage, no roar of equipment, strolling in the concept factory, only to see the ring corridor, green grass, shallow pond, distant paddy fields like mirrors, Yan Mo crisscrossing, a beautiful Jiangnan scenery. "A factory from afar, a park up close", this new concept factory completely subverts the reporter's perception of traditional sewage treatment plants.
"In general, wastewater treatment plants have a strong 'NIMBY' effect." Zhang Yifei said that "NIMBY" refers to the collective opposition or even protest of residents or local institutions because they are worried about the negative impact of certain public facilities projects on physical health, environmental quality and asset value. "Even if you hear that a sewage treatment plant is going to be built nearby, most residents will basically raise objections."
To solve the "NIMBY" effect, we must be environmentally friendly. The concept factory adheres to the concept of green development, and under the premise of ensuring that water quality and organic matter recycling facilities are relatively fixed, it extends to modern agriculture, sports, cultural tourism, ecological pastoral and other fields according to local conditions, creating an open and shared new urban space, and integrating and coexisting with the surrounding environment without feeling.
The reporter noticed that the primary sedimentation tank, biochemical pond, secondary sedimentation tank, etc. in the factory area were covered, and an odor treatment device was installed next to it, which basically did not produce odor in the entire sewage treatment link. In the organic matter co-treatment center, the gas is purified before discharge, so there is almost no odor. According to reports, the concept factory adopts combined biological deodorization technology, greatly reduces the total amount of odor through refined design, and ensures that the plant area has no peculiar smell through the combination process of "dust removal water washing + pickling + high-efficiency heterotrophic biological deodorization filter" to achieve the unique needs of opening up to the outside world.
The new concept is also reflected in the details of the architectural design. The reporter saw that an oblique chimney was installed in the organic matter collaborative processing center. "As for why it is inclined, it is purely an aesthetic consideration of the architect, the chimney is not necessarily straight, the inclination is also a kind of beauty, very artistic and eclectic." The factory staff responded. It is reported that the concept factory area is designed by artists, architects and engineers, paying attention to the beauty of architectural space and the integration of cultural landscape, making the factory area like a beautiful urban guest exhibition hall and a public garden for citizens' leisure and entertainment.
"Our café and garden here have become local Internet celebrity check-in points, and people often come to take wedding photos, which is very lively during holidays." Zhang Yifei said that it is necessary to promote the integration of sewage treatment plants and the urban environment, change the "negative" space into a "positive" space, realize from "NIMBY" to "neighborly benefit", and build a new environmental infrastructure that integrates and interacts with ecology, life and production, and serves society and nature.
"Yixing Urban Sewage Resources Concept Plant is the first new concept water plant cooperated by Three Gorges Group, and the concepts and achievements here are being promoted and applied in the protection of the Yangtze River." Liu Xianghua, deputy secretary of the party committee of Changjiang Ecological Environmental Protection Group, said that through preliminary practice, a number of new concept factories such as Anhui Lu'an Phoenix Bridge Water Quality Purification Plant and Hubei Wuhan Tangxun Lake Zanglong Island Underground Water Purification Plant will be replicated and built to create a unique and efficient "weapon" for ecological governance of the Yangtze River, which will actively promote the green innovation and high-quality development of the Yangtze River Economic Belt. (Duan Xiangyu, reporter of China Discipline Inspection and Supervision News)