2. Chemical method: chemical algae removal and chemical fixation of heavy metals;
3. Biological method: biological contact oxidation and ecological restoration.
Sewage interception and diversion is to collect the sewage directly discharged into urban rivers to urban sewage treatment plants or constructed wetlands through the construction of rain and sewage pipe networks, and then discharge them after treatment to reduce the total amount of pollutants discharged into rivers;
In fact, water diversion and pollution flushing is to replace the polluted river water by purifying the river water, and dilute or bring the pollutants in the original polluted river downstream, thus reducing the pollution load of the river and improving its self-purification ability;
Sediment dredging is to reduce the release of pollutants from sediment to water by dredging sediment, which can permanently remove pollutants from sediment and effectively reduce endogenous pollution;
Aeration reoxygenation technology is mainly used to deal with the sudden pollution of rivers, that is, artificially reoxygenation of rivers at appropriate positions to improve the dissolved oxygen level of water bodies, restore the vitality of aerobic organisms in water bodies, enhance the self-purification ability of water bodies, and thus improve the water quality of rivers;
Chemical algae removal is to destroy collagen in water by adding chemical agents, so as to achieve the purpose of algae removal;
Chemical fixation of heavy metals means that heavy metals in river sediments will enter the water body in ionic state or in some combined state under certain conditions, but by adding alkaline substances to improve the pH value of river water, heavy metals will form insoluble sediments such as silicates, carbonates and hydroxides and be fixed in the sediments;
Biological contact oxidation process is mainly based on carriers such as biofilm attached to natural riverbed and artificially filled filter materials, and removes pollutants from river water through adsorption, degradation and filtration under the conditions of artificial auxiliary aeration or direct utilization of dissolved oxygen in water.
River ecological restoration refers to the use of ecosystem principles to repair the damaged water ecosystem and restore the ecological groups and structures in the river, so that the river ecosystem has a reasonable organizational structure and good operational functions, and can remain stable under long-term or sudden disturbances.
Extended data:
Current situation of rivers:
From the perspective of the universe, the earth is a blue planet with a very rich water storage capacity of 65.438+0.45 billion cubic kilometers, and 72% of its area is covered by water.
But in fact, 97.5% of the water on the earth is salt water (96.53% of which is ocean water, 0.94% is lake salt water and underground salt water), which is salty and bitter and not suitable for drinking, irrigation and industrial application. There is very little water that can be directly used by people, only 2.5% fresh water.
Nearly 70% of fresh water is frozen in the ice sheets of Antarctica and Greenland, and most of the rest is soil moisture or deep groundwater, which is difficult for human beings to exploit. Water from rivers, lakes, reservoirs and shallow groundwater is easy to be exploited for human direct use, but its amount is less than 1% of the world's fresh water, accounting for about 0.007% of all water on the earth.
Baidu Encyclopedia-River Pollution