Outside the beautiful Zhongjiang City, there is a Kaijiang River. Kaijiang is a river that flows through several major cities and counties. In the river basin across the Zhongjiang River, a large amount of domestic sewage is discharged into the river every day, and some unscrupulous citizens throw garbage directly into the river. In this case, I really can't compliment the water quality of Kaijiang. However, when I saw the clear water in the lower reaches of Kaijiang River, I couldn't help wondering why the river was still "muddy but not polluted" after so much pollution. Is there any "mystery" in this? In order to make students form a good awareness of environmental protection, the school specially organized some students to visit Zhongjiang Maoerzui Sewage Treatment Plant, and my long-standing questions were also answered here.
Walking into the factory, rows of light blue factories are displayed in front of us, with neat planning and large green area. The Director of Environmental Protection Bureau gave us an overview of the sewage treatment plant:
The design of Maoerzui Sewage Treatment Plant began at the end of 2002, but the design was forced to be suspended due to problems such as funds, site selection and house demolition. It was not until 2007 that the design was restarted with the attention of Deyang Municipal People's Government. Wenchuan earthquake occurred on the way, and it was officially completed in June 2009.
The first step of sewage treatment is filtration. The sewage flowing in from the upstream must first pass through two sets of backward inclined coarse grids to intercept the larger floating objects in the sewage to protect the pump from damage. The grid is a galvanized strip with sufficient rigidity and strength to avoid being bent by large floating objects, and the sewage enters the fine grid after passing through the pump room. There are a lot of small floating objects in urban sewage, such as leaves, plastic belts and vegetable residues. They can easily pass through the thick Geshan to reach the treatment structure and float on the water surface, which affects the subsequent oxygenation process. At this time, the fine grid will come in handy-the garbage intercepted by the two grids will be dehydrated by the screw dehydrator and then pumped to the ground by the slag pump.
The oxidation ditch looks like a huge basin from the outside, and we stood on the edge of the basin when we visited it. Dozens of pumps work together to form a series of small doors in the center of the oxidation ditch. Through this system, water will be rich in oxygen. Before the sewage flows, some duckweeds float on the sewage. Water is brown and yellow. As it flows, it gives off a strange smell, so we can't help covering our noses and mouths. After aeration in the oxidation ditch, relatively pure sand particles can be obtained, and sand particles larger than 0.2mm are precipitated in the sedimentation tank, of which organic matter accounts for only 5%.
After these processes, the river is basically clear, and they are greeted by the last checkpoint-the reflux pool. Introducing Cl2 into water can kill invisible harmful bacteria in water. After passing through the reflux pool, fresh water can be seen flowing out, and there is no smell. On the contrary, it feels cool and pure, and it really turns decay into magic.
On the way home, the secretary's words reminded me that sewage treatment is a measure that the country should take to worsen the environment and is everyone's responsibility. For Zhongjiang, it is the guarantee of Kaijiang water quality and the premise that Santai County's water use will not be affected.
As we all know, water is like the lifeblood of everything on earth. Therefore, whether we should cherish and try our best to keep the rivers dry, blindly abusing and polluting water resources is tantamount to drinking poison to quench thirst. Protecting water resources is not only an act of criticizing waste and pollution, but also a giant.