As for artificial wetlands, it can be said that they have a long history in China. China has had its own artificial wetlands since people started farming and cooking. Those rice fields, artificial fish ponds, etc. are the most qualified old people in the artificial wetlands, and they will tell people stories about the wetlands. Month after month, year after year, they work tirelessly to carry out the great cause of environmental protection. Until one day, people gave them a formal name - constructed wetland! The constructed wetland technology originated in the 1950s. After decades of development, it has become a relatively mature sewage treatment technology and has been applied on a large scale in developed countries in Europe and the United States. In recent years, this technology has also been widely used in our country and has produced good environmental governance effects.

What is so magical about artificial wetlands? How can they be used to purify water and restore water bodies? A constructed wetland is an artificially constructed and supervised surface similar to a swamp. In the environmental field, the research and application of constructed wetlands to treat sewage is becoming more and more extensive. In the process of sewage flowing in a certain direction, the triple synergy of physics, chemistry, and biology in the natural ecosystem of wetlands is mainly used to filter, adsorb, and * ** sedimentation, ion exchange, plant absorption and microbial decomposition to achieve efficient purification of sewage. Please read below: Report "Constructed Wetland: Beautiful Landscape by Fuxian Lake".

1. Constructed Wetlands: Using Nature’s Method to Control Pollution “A large flock of seagulls flew over Fuxian Lake!” People in the Yaonigou area on the north shore of Fuxian Lake were arguing about the red-billed gulls from Siberia. . What force attracts hundreds of gulls to fly to the north bank of Fuxian Lake? Environmentalists revealed the secret: Fuxian Lake has blue sky and clear water, and the artificial wetlands have allowed seagulls to find a new home.

In June 2002, after careful design by the Nanjing Institute of Geography and Limnology of the Chinese Academy of Sciences and the Yuxi Environmental Science Institute, the first large-scale artificial wetland in Yunnan Province was built in Yaonigou on the north bank of Fuxian Lake. , the foul-smelling sewage flowing into the lake turned into a clear trickle after flowing through the artificial wetland. In October 2003, the second artificial wetland was built and put into use on the north bank of the Maliu River. Monitoring results from the environmental protection department show that the effluent quality of the Yaonigou constructed wetland reaches the Class III surface water standard, and the effluent quality of the Maliuhe constructed wetland reaches the Class II surface water standard. Arriving at the mouth of the Maliu River on the outskirts of Chengxian County, the reporter saw a magical artificial wetland. At the entrance of the wetland, workers salvaged garbage and floating objects from the water. After passing through the slag gate, the black sewage slowly flowed into the wetland. This artificial wetland covering an area of ??nearly 30 acres is built in the shape of several "fields", separated by cement ridges. More than 10 kinds of aquatic plants, such as cattails, reeds, water celery, water lilies, cannas, and Malay vegetables, are planted in different areas. plant. After sewage enters the artificial wetland, the first pool it flows into is the biological oxidation sedimentation tank. The sewage is oxidized in the pool. After the phosphorus, nitrogen and other nutrients in the sewage are filtered and fully absorbed by these plants, the nutrients contained in the sewage have been greatly reduced. ; and then flows into a pond paved with sand and stones and growing plants. The sewage is precipitated and filtered again in the underground flow; the last process is completed in the surface shallow flow biological purification tank. The algae and aquatic plants in the pond absorb the nutrients in the water again, The sewage at this time has become crystal clear. At the water outlet not far from the lake, the originally turbid and foul-smelling sewage has turned into a clear spring, flowing into the beautiful Fuxian Lake. The ability of constructed wetlands to treat sewage is amazing. Yaonigou is one of the more polluted rivers entering the lake on the north shore of Fuxian Lake. After the completion of the Yaonigou constructed wetland covering an area of ??26 acres, it can treat 10,000 tons of sewage per day. Monitoring shows that after sewage is treated in constructed wetlands, the total nitrogen and total phosphorus removal rates are 50% and 40% respectively, the suspended solids removal rate is more than 80%, and the chemical oxygen demand and biochemical oxygen demand removal rates are 60%. % and 50%, the water quality is improved by 1 to 2 levels. According to reports, the pollution control effect of the Maliuhe constructed wetland is better than that of the Yaonigou constructed wetland, and the effluent water quality reaches Class II surface water standards.

2. Ecological benefits: Seize the throat of non-point source pollution

Agricultural non-point source pollution is the biggest killer of the Fuxian Lake water body. Non-point source pollution such as domestic sewage and farmland runoff are the leading causes. The main reason for the decline in water quality. According to statistics, the amount of chemical fertilizers applied in the Fuxian Lake runoff area in 2002 was 49,681 tons, of which about 20% of nitrogen fertilizers and 15% of phosphorus fertilizers were lost with water; nearly 30 tons of pesticides were applied, and about 30% of them were lost. These directly contributed to the total loss of Phosphorus and total nitrogen are elevated. Monitoring results from the environmental protection department show that 2,487 tons of nitrogen fertilizer and 1,000 tons of phosphate fertilizer enter the Fuxian Lake runoff area every year, posing a serious threat to the ecological environment of the lake area. Crop waste and domestic garbage flow into the lake along the river, also causing pollution. Currently, 33,600 tons of garbage flow into the lake every year. The annual discharge of domestic sewage in rural areas in the Fuxian Lake runoff area is 4.06 million tons, and the discharge of human and animal feces is 600,000 tons. A considerable part of these pollutants enter Fuxian Lake through surface runoff and stratum seepage. The Maliu River is one of the more polluted rivers in the suburbs of Chengjiang County. There are large areas of farmland on both sides of the river. Chemical fertilizers, pesticides and crop waste flow into Fuxian Lake along with the river water. Some of the county’s domestic sewage and domestic garbage also flow into it. The lake, especially during the rainy season, is in a mess at the entrance of the Maliu River into the lake. Due to the ravages of sewage and garbage, the nearby lake water has become eutrophic, and what was once a good swimming place has become a dirty pool.

Now, the Maliuhe constructed wetland is put into use. The garbage is salvaged by workers at the entrance of the constructed wetland. All the sewage flows into the wetland. The sewage is "washed" before flowing into the lake. In the next few years, a large-scale artificial wetland will be built beside Fuxian Lake. A 9-kilometer waste interception ditch, 100 hectares of artificial wetlands, and 700 hectares of landscape wetlands will be built on the north bank of Fuxian Lake. Xu Shaowu, director of the Chengjiang County Environmental Protection Bureau, said that by 2010, Chengjiang alone will build 28 pollution control projects at the end of rivers entering the lake, and the main content will be the construction of artificial wetlands. After the large-scale construction of the Fuxian Lake constructed wetland, the constructed wetland will control the main rivers that spit pollution into Fuxian Lake and choke the throat of non-point source pollution.

3. Economic benefits: low sewage treatment costs

During the interview, Ma Defen, deputy director of the Chengjiang County Environmental Protection Bureau, calculated the following: Chengjiang County sewage treatment plant processes 4,000 sewage per day tons, and it costs 0.98 yuan to process 1 ton of sewage, with a daily investment of nearly 4,000 yuan; while the Maliuhe constructed wetland has a daily sewage treatment capacity of 14,500 tons, and only costs 0.03 to 0.05 yuan to process 1 ton of sewage, with a daily investment of only a few hundred Yuan, that is to say, the sewage treatment cost of constructed wetlands is only 1/20 of that of sewage treatment plants.

4. Social benefits: After sightseeing, I got inspiration from the Masiaohe artificial wetland. The dozens of acres of artificial wetland are like an environmental protection picture. The artificial wetland can "turn sewage into a clear stream" and it is amazing. Walking on the ridge between the wetlands is like walking in a lakeside park. The well-known and unknown plants in the wetlands show people their strong vitality while absorbing dirt and evil. The surrounding water is gurgling. If you are interested, you can climb on it. Get on the boat, pick and manage these lovely creatures with the workers, and experience a "Puzhehei Journey".

For a time, while controlling pollution, the artificial wetland also became a beautiful landscape beside Fuxian Lake. In recent years, many wetlands where nature has blessed humans have become tourist hot spots. In Tengchong, Yunnan, the Beihai Wetland, a national nature reserve, has become a highlight of tourism, attracting more and more tourists. In some places, artificial wetlands have also become tourist spots and environmental education bases.

It can be seen that once the artificial wetland is built, it will be a beautiful scenery. Not only can it spend very little money to treat sewage, but at the same time, it can also build a scenic spot. This is probably the case for the green environmental protection we have always advocated.