Primer

"Keep the two bottom lines of development and ecology" - this is the clear requirement of General Secretary Xi Jinping for Guizhou's reform and development.

On the eve of the Spring Festival this year, when General Secretary Xi Jinping went to Guizhou to visit cadres and people of all ethnic groups, he came to Wujiang River, the largest river in Guizhou Province and the largest tributary on the right bank of the upper reaches of the Yangtze River, for investigation and research. The Wujiang River basin covers 7 cities (prefectures) and 47 counties (cities and districts) in Guizhou, bearing more than half of the population and economic aggregate of the province. For some time, the water of Wujiang River has been polluted due to extensive operation of industrial enterprises along the river, overloading of cage culture along the river, and lagging sewage treatment on both banks.

In recent years, Guizhou has launched an "iron fist" pollution control storm, and the ecological environment quality of Wujiang River has been significantly improved.

"How do you manage it?" asked the General Secretary.

"We have focused on several key points. On the one hand, we have strengthened the prevention and control of phosphorus chemical pollution, taking the lead in implementing the" fixed production based on slag "of phosphogypsum in the country; on the other hand, we have strengthened the prevention and control of non-point source pollution, and 98 domestic sewage treatment facilities have been built and put into operation in counties and central cities in the basin, realizing full coverage," said the local leader.

"Do you still use cages to raise fish?" the General Secretary asked again.

"We took the lead in banning cage fish farming in the whole basin, while comprehensively implementing the ten year ban on fishing in the Yangtze River."

The General Secretary was very pleased.

Adhering to the principle of "jointly focusing on major protection and not engaging in major development", we should stick to the bottom line of development and ecology. Guizhou has made concerted efforts to defend the clean water in the Wujiang River basin, and comprehensively strengthened the environmental governance of the Wujiang River basin. The water quality of the main stream of the Wujiang River in Guizhou has improved year by year from the inferior five categories. In 2020, it reached the second category standard for the first time, and the annual average concentration of total phosphorus, the primary pollutant, has decreased by 93% compared with 2012, The annual average concentration of ammonia nitrogen decreased by 75% compared with 2012.

The restoration of the water quality of the main stream of Wujiang River in Guizhou to Class II is a microcosm of the turning changes in the ecological environment protection of the Yangtze River Economic Belt. The reporter recently made a field visit along the Guizhou section of the Wujiang River to explore the stories and experiences of Wujiang River pollution control to grasp the key points and fight hard.

Treatment of industrial waste residue, focusing on treatment of phosphorus chemical pollution

Implement "slag based production", continue to treat the leakage of phosphogypsum slag field and phosphorus containing wastewater, and the annual average concentration of total phosphorus in the main stream of Wujiang River has dropped by more than 90% in 8 years

Stepping on the water and going upstream along the Wujiang River, the speedboat slowly decelerates to the water area of Wujiang Town, Bozhou District, Zunyi City, Guizhou Province. Standing at the bow of the boat and leaning against the railing, the clear stream of spring 34 was bubbling in the setting sun.

"When Wujiang River is clear, we can walk along the river again." The young man turned into an old man. Apart from a strong accent, Li Longkun has long regarded Wujiang Town as his second hometown.

In April 1970, the construction of Wujiangdu Hydropower Station began in Wujiang Town. Li Longkun, 35 years old at that time, came here from Anhua County, Hunan Province to participate in the construction of the power station project, and has taken root since then. "When I was thirsty, I went to the riverside to drink water directly. It was cool and sweet."

When Li Longkun was busy at the construction site of the hydropower station, a karst spring near the Wujiang River, not far from the construction site, had quietly boarded the regional hydrogeological survey report and was labeled as "No. 34 Spring of Wujiang River".

After retirement from the hydropower station, Li Longkun chose to stay in Wujiang Town for his old age. A small bench and a fishing rod often sit for most of the day by the river. In his leisure days, he became more attached to Wujiang River. This leisurely retirement life lasted for more than ten years, until March 2009, there were some abnormal changes in Wujiang.

"The river suddenly turns white, and the hands are smooth and greasy. There is also a sour smell, so it is impossible to fish." Li Longkun shook his head and sighed.

Local experts were quickly organized to go to the scene to find out the cause. The survey found that the total phosphorus concentration and fluoride concentration in No. 34 spring were 1499 times and 119 times higher than the standard respectively, and the sections in Zunyi of Wujiang River below the spring were all inferior to Class V water quality.

Where does pollution come from? The environmental protection department organized expert consultation, and finally found the pollution source in Paishan Village, Xiaozhaiba Town, Xifeng County, Guiyang City, 11.4km away. There is a slag yard called Jiaoyishan, which was built and put into use by Guiyang Sinochem Kaifeng Phosphate Fertilizer Co., Ltd. (now Guiyang Kaifeng Phosphate Fertilizer Co., Ltd.) in 2006. In just a few years, phosphogypsum waste slag has piled up into a hill.

"The main pollution problem in the Wujiang River basin is that the total phosphorus concentration exceeds the standard, the key is to control the phosphorus chemical pollution, and the key is to absorb phosphogypsum." Luo Hongxiang, the ecological environment supervisor of the Department of Ecological Environment of Guizhou Province, introduced that Guizhou is an important phosphorus and phosphorus chemical production base in China, especially the Wujiang River basin is rich in phosphorus mineral resources, and there are many large phosphorus chemical enterprises along the coast. "Due to the general lack of anti-seepage design in the slag yards built in the early stage, coupled with Guizhou's karst landform and many karst caves, the high concentration phosphorus containing sewage produced by phosphogypsum is easy to enter the underground river, and thus seep into the Wujiang River."

Looking at the Guizhou Water Resources Bulletin from 2009 to 2013, a group of data about the proportion of the Wujiang River in the annual monitoring and evaluation reaches with inferior water quality of Class V was striking: 59.4%, 66%, 54.8%, 51.2%, 54.8% - which means that more than half of the Wujiang River in the monitoring and evaluation reaches with inferior water quality of Class V in five years.

Pollution control is urgent. In 2012, the Wujiang 34 spring water pollution control project was listed as the "No.1 project" of Guizhou Provincial Government for environmental pollution control. Guiyang Kailin Fertilizer Co., Ltd. built two sewage return pipelines in 2012 and 2013 respectively. In March 2015, No. 34 Quanyan Sewage Treatment Station was officially put into use. After the high concentration phosphorus containing wastewater was pumped out, it was treated in neutralization tank, sedimentation tank, filter tank and other links, and can be discharged up to standard. However, the treatment capacity cannot keep up with the water inflow, and the pollution belt cannot be eradicated all the time.

The problem is in the water, the root is on the shore. Leaders of the Guizhou Provincial Party Committee and the Guizhou Provincial People's Government successively went to the Wujiang No. 34 Spring to conduct field investigation, requiring enterprises to closely cooperate with relevant departments to fight the battle for the protection and restoration of the Wujiang River, so as to ensure the effective treatment of pollution. Since 2016, Guiyang Kaifeng Phosphate Fertilizer Co., Ltd. has changed its thinking to focus on the treatment of Jiaoyishan slag field, and comprehensively covered the phosphogypsum accumulation to prevent the phosphogypsum waste from seeping into the underground river. The accumulated cost of project construction and operation has exceeded 1.5 billion yuan. In 2018, the overall water quality of the downstream reach of No. 34 Spring was improved to Class III.

The No. 34 spring water pollution control project is a microcosm of Guizhou's efforts to control the Wujiang River pollution by grasping the key points.

According to the data in 2017, the stock of phosphogypsum piles in Guizhou exceeds 100 million tons, with an annual increase of tens of millions of tons. How to treat both symptoms and root causes? Since 2018, Guizhou has implemented strict management of total phosphorus emission limits, continued to control the leakage of phosphogypsum slag yard and phosphorus containing wastewater, implemented the backpressure mechanism of "determining the production based on the slag", determined the output based on the phosphogypsum consumption and utilization capacity, and required enterprises to fully consume and utilize the newly generated phosphogypsum in the current year.

"It's either to reduce production or to transform, and 'to determine production based on slag' forces us to take practical measures to digest phosphogypsum." Liao Jixing, general manager of Guiyang Kaiping Phosphate Fertilizer Company, said that the company has made a combination of efforts to turn waste into treasure: on the one hand, phosphogypsum is used as aggregate to backfill the mined out areas of phosphorus mines; On the other hand, relying on R&D advantages, improve the comprehensive utilization rate of phosphogypsum resources and develop green building materials such as cement retarders.

In June 2019, Kailin and Wengfu, two major phosphorus chemical enterprises in Guizhou Province, were reorganized into Guizhou Phosphate Chemical Group. An important mission of the Group is to optimize resource allocation and focus on solving the problem of phosphogypsum waste residue.

"Look, the tea table, hanging pictures and these ornaments in my office are all made of phosphogypsum." Deng Zhulin, deputy general manager of Guizhou Phosphate Chemical Group, pointed to a dazzling array of phosphogypsum building materials. Since the implementation of the "slag based production" policy, the Group has increased investment in comprehensive utilization, research, development and promotion of phosphogypsum, and is committed to creating new economic growth points. At the same time, phosphogypsum is used for filling and replacing ore pillars in the mine after modification, and the recovery rate of phosphate ore resources is increased from about 50% to more than 90%, effectively solving the problem of surface collapse in the mining area.

With the continuous deepening of resource utilization, the utilization and disposal rate of phosphogypsum in Guizhou Province has increased from 43% in 2017 to more than 100% in 2020, realizing the annual production and sales balance of phosphogypsum for the first time. In 2020, the annual average concentration of total phosphorus, the main pollutant in the main stream of Wujiang River, will decrease by 93% compared with 2012, and the annual average concentration of ammonia nitrogen will decrease by 75%.

Domestic sewage treatment focuses on improving treatment capacity

In the Wujiang River basin, cities above the county level have achieved full coverage of sewage treatment facilities, with an average daily sewage treatment capacity of 3.4 million tons

There are many birds singing and flowers fragrant on the ground, and many tourists; The underground pipe network is densely distributed, and the water flow is surging... It is hard to imagine a reclaimed water plant hidden under your feet when you enter the live water landscape park of Qingshan reclaimed water plant on the east bank of Nanming River in Guiyang City. As the first fully submerged sewage treatment facility in Guizhou Province, Qingshan Reclaimed Water Plant has a daily sewage treatment capacity of 50000 tons, and can supplement about 18.5 million tons of ecological landscape water to Nanming River every year.

At dawn, the 82 year old Bai Chengyang came to the living water landscape park to stretch with his partners. "The water here is clear, the trees are green, the air is fresh, and the street away from the community is a good place for morning exercises at home." Bai Chengyang has lived by the Nanming River for most of his life, but a few years ago, the old man would rather walk around than pass by the Nanming River. The window on the side of the river in his home is closed all the year round.

Nanming River is a primary tributary on the right bank of Wujiang River, with a total length of 185 kilometers. It flows through five districts and counties of Guiyang City, with a total population of 3.1 million. In the 1990s, with the rapid progress of urbanization, there were nearly 100 domestic sewage outlets on both sides of the river, discharging about 450000 tons of sewage into the river every day. "At that time, the river was shallow, black and smelly," Bai Chengyang said.

Sun Yang, director of the Water Supply and Reclaimed Water Division of Guiyang Water Affairs Bureau, introduced that at the beginning of the treatment of domestic sewage in Nanming River, the end treatment mode of "upstream collection along the way and downstream centralized treatment" was mainly adopted, that is, a sewage treatment plant was built in the downstream suburb, and the sewage along the bank was transported and treated remotely through laying pipe networks, but the siltation was heavy, the water body was black Problems such as strong odor still exist in the Nanming River basin.

Why is it "hard to cure for a long time"? On the one hand, Nanming River is short of water, the flow of ecological base is small, and the river has low capacity to accept pollutants. On the other hand, the main urban area of Guiyang has a large population density and belongs to a typical karst landform. It is difficult to collect, transport and construct sewage. The cost of pipe network construction and maintenance is high. The sewage intercepting ditch and terminal treatment plant have been overloaded for a long time, and sewage leakage and overflow often occur along the way.

Kong Hainan, a professor of the School of Environmental Science and Engineering of Shanghai Jiaotong University and the chief scientist of the major national water pollution control and governance science and technology project, who participated in the governance of Nanming River, suggested: "Can we break up the whole into parts and change the centralized treatment of the downstream to the sectional treatment along the line?"

"The direction is correct, but the difficulty is not small." Sun Yang said that the main urban area of Guiyang is full of tall buildings, and the construction space of the sewage treatment plant is limited. When the treatment scheme met the bottleneck of land use, the ecological sinking reclaimed water plant project developed by China Water Environment Group attracted the attention of Guiyang City. The reclaimed water plant is built in the form of full burial, and its floor area is only 1/3 of that of the traditional sewage treatment plant.

In 2014, Guiyang City introduced China Water Environment Group and invested 350 million yuan to build Qingshan Reclaimed Water Plant, which is located on the bank of Nanming River opposite Bai Chengyang's home. "I support the construction of a sewage treatment plant, but it's better not to build it next door to my home." Bai Chengyang not only hopes that the Nanming River will be cleared as soon as possible, but also worries because the sewage treatment plant is close to his community.

"The reclaimed water plant has mature technology, which has solved a series of safe operation problems such as flood control and odor treatment, and will not bring trouble to residents' lives." Zhou Fubo, the director of Qingshan reclaimed water plant, took the initiative to communicate at home, working from house to house, trying to dispel residents' concerns. After the completion of the water plant, Bai Chengyang and the neighbors were invited to visit. At first, they were skeptical. They did not expect to take photos joyfully as soon as they stepped into the gate - there was no roaring machine in front of them, but there was an open ecological green park covering an area of 34 mu. The Qianqian reeds were swaying in the wind, and the clear stream was flowing slowly beside the waterwheel

Into the Qingshan reclaimed water plant on the ground floor, there is no odor in the huge plant area. Originally, the reclaimed water plant used three combined methods of water cleaning solution cleaning, activated carbon adsorption, and packed microbial deodorization to treat sewage, minimizing air pollution. At the same time, the main processing equipment is arranged at a depth of 15 meters underground, and the mechanical vibration is low, which has no impact on the ground buildings.

"The sunken water plant is like being built in a closed box buried deep underground." Zhou Fubo called it "space folding", which effectively reduces the investment and operation costs of the pipe network while optimizing land use. If the plant is built in the downstream suburb in the traditional way, the construction of sewage transmission and reuse pipe network is a big expense. Now, the reclaimed water plant is built in the urban area, saving 1.5 billion yuan in investment on the main sewage collection pipe alone.

Sun Yang introduced that since 2017, Guiyang has built 20 new sewage treatment plants, 14 of which are sunken. At present, there are 34 reclaimed water plants in the Nanming River basin. "These reclaimed water plants are distributed along the main and tributaries of the Nanming River like" vines and melons ", and the tail water will be discharged into the river after reaching the standard, becoming a stable source of recharge, and the ecological self purification capacity of the river will be greatly improved."

By 2020, the average daily sewage treatment capacity of the Nanming River basin will reach 1.8358 million tons, 1.85 times that of 2017; It can provide 1.5 million tons of ecological water supplement to Nanming River every day, saving 500 million tons of cross regional water supplement every year; All 33 black and odorous water bodies in the basin have been eliminated.

In recent years, Guizhou has continued to focus on domestic sewage treatment in the Wujiang River basin. At present, the sewage treatment facilities in cities above the county level in the basin have been fully covered, with an average daily sewage treatment capacity of 3.4 million tons.

Ban cage farming and promote green transformation and development

All 1201 retired fishermen in the Wujiang River Basin of the province went ashore

A "runway" is built in the fishpond, and the fish grow in the "surfing". Wang Liangzhang, 57 years old, walked into the flowing water fish breeding base in Bahe Village, Shiban Town, Bozhou District, Zunyi City. The ecological fishery technology made the visitors praise.

Clear water flows down from the upstream dam, through a 500 meter long ditch, and continuously flows into more than 30 dissolved oxygen aquaculture ponds. A closer look shows that the pool is splashed with water, and the fish are alive and kicking, including carp, channel catfish and other varieties. The aquaculture pond simulates the water flow environment in the natural state. With the help of water flow acceleration technology and water circulation system, the fish can carry out aerobic exercise 24 hours a day.

"The fish is like exercising on a 'treadmill'. The amount of exercise is increased, the meat is firm, and the taste is better." Wang Liangzhang quipped. Previously, he raised fish in cages in the Wujiang River. Every year, he put more than 200 tons of feed into the cages.

"Excess feed turns the river yellow, and you can smell the fishy smell from afar. The dense cages also affect the safety of the boat, blocking the floating garbage." Wang Liangzhang also knows that cage farming pollutes the environment, but in order to make the fish grow faster, he will still put a lot of feed into the water. The data in 2015 showed that the daily feeding amount of cage aquaculture in the Wujiang River basin reached 62000 kg, which had a serious impact on the water supply environment.

In the second half of 2017, Guizhou kicked off the nationwide ban on cage farming.

Guizhou has invested 600 million yuan in the demolition of 9579 mu breeding cages in the Wujiang River basin, effectively reducing the eutrophication of water bodies.

What about fishermen's livelihood after they go ashore? Where will the "Wujiang Fish" brand go? Guizhou has put forward a green transformation plan - to guide some retired fishermen to transform and develop ecological fisheries through vocational skills training and the promotion and application of new technologies.

In February 2017, Bozhou District introduced the pond circulating water aquaculture technology for the first time in the province. Through manual intervention, the water body circulates in the pond, and fish are raised in a fixed running water pond, effectively collecting fish excreta and leftover feed, and finally processing it into efficient organic fertilizer for melon, fruit, flowers and other plants, so as to achieve zero discharge of aquaculture wastewater.

In September 2017, the demonstration base of running water fish culture in Bahe Village with an investment of more than 22 million yuan was completed, and Guizhou Yuyuzui Ecological Breeding Company put in the first 100000 speartail fry here. Wang Liangzhang was employed as a technician with a minimum monthly salary of 6000 yuan. According to the agreement with the company, he can also participate in the dividend when selling fish at the end of the year.

The same is fish farming, but the method is very different from the past. The Wujiang River fish growing in flowing water is full of vitality and basically does not use fish medicine. According to Wang Liangzhang, cage fish farming in Wujiang River was easy to induce fish diseases due to high water temperature in summer. Today, the water temperature in the running water aquaculture pond is only 24 ℃ at 35 ℃, which is suitable for fish growth.

"I thought that after the cage was removed, the 'rice' of fish farming would be impossible. I didn't expect to continue to work after landing, and the purse was even bigger than before." At the beginning of the ban on cage, Wang Liangzhang had misgivings. Now looking at the lively fresh fish, and seeing the water in Wujiang River getting clearer and clearer, I don't want to mention how comfortable it was.

The flowing water makes the fish fat, and the river is clear and the fish are thriving. In April 2019, the General Office of Guizhou Provincial People's Government issued the Guiding Opinions on Accelerating the Development of Ecological Fisheries, which clearly put forward the goal of "zero cage · ecological fish", put the concept of green development through the whole process of aquaculture production, and promote the balanced development of fisheries with high efficiency, high quality and high output. So far, Guizhou has built 19 provincial ecological fishery development demonstration counties (districts) such as Bozhou, implemented 100 ecological fishery demonstration projects, and formed a brand system of Guizhou ecological fish based on the public brand of "Guishui Qianyu", supplemented by regional characteristic brands. In 2020, the province's ecological fishery output value will reach 6.109 billion yuan.

The development of ecological fishery reflects the efforts and achievements of the green transformation development of the Wujiang River basin. In accordance with the requirements of the 10-year fishing ban of the Yangtze River, Guizhou has developed ecological fisheries, vegetables, fruits, animal husbandry and other industries, and helped 1201 retired fishermen in the Wujiang River Basin to go ashore.

At the same time, Guizhou has strict environmental access to the Wujiang River basin. During the "13th Five Year Plan" period, 222 Wujiang River basin construction projects were not approved due to industrial access policies, major environmental impacts and other reasons, involving 30.53 billion yuan; 1473 illegal cases of water pollution in the Wujiang River basin were investigated and dealt with according to law.

In 2020, the annual output of the project will be 450000 kg, and the output value will be 4.5 million yuan. It will drive more than 200 local people to find jobs, and develop into the largest "Wujiang Fish" guarantee supply base and flowing water fish breeding base in Zunyi City. With the continuous expansion of production capacity, in 2020, Guizhou Green Industry Poverty Alleviation Investment Fund decided to give a support fund of 8.98 million yuan to Yuyuzui Ecological Seeding and Breeding Company to support the running water fish farming project in Bahe Village in the mode of "Party branch+company+village collective+farmers" to drive more people to increase income and become rich.

"The water of Wujiang River is clear, and our days are brighter." Wang Liangzhang's eyes are shining as he gazes at the river.

Originally published in People's Daily (the 13th edition on August 13, 2021)

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