Water pollution governance is largely due to human emissions of various exogenous substances (including nature, there are already some and no), after entering the water, the water itself is beyond the self-purification (that is, rivers and lakes can be through a variety of physical, chemical and biological methods to eliminate the exogenous substances) can afford pollution water treatment, and control.Human activities can make a large number of industrial, agricultural and life waste discharged into the water, the water is polluted. At present, the world each year about 4200 cubic meters of wastewater discharged into rivers and lakes, the pollution of 5.5 trillion cubic meters of water, it is the equivalent of more than 14% of the world's total runoff.
Pollution has two kinds: one kind is the natural pollution; Another kind is man-made pollution. The larger is man-made pollution damage to the water body.
According to the different of pollution of impurities and water pollution are divided into chemical pollution, biological pollution and physical pollution three categories.
(1) without treatment and discharge of industrial waste water;
(2) and untreated sewage discharge;
(3) the heavy use of chemical fertilizers, pesticides, herbicides of farmland wastewater;
(4) industrial waste and life rubbish piled up in the river;
(5) soil erosion;
(6) mine wastewater.
