Water resources pollution and its control

Water pollution is mainly caused by pollutants produced by human activities, including mine pollution sources, industrial pollution sources, agricultural pollution sources and domestic pollution sources.

1. Classification of wastewater pollution

Groundwater is different from surface water and is regarded as the "life water" of human beings. Contaminants entering groundwater come from both human activities and natural processes.

A. Wastewater has different classification methods from different angles

(1) According to different sources, it is divided into two categories: domestic wastewater and industrial wastewater;

(2) According to the chemical category of pollutants can be divided into inorganic wastewater and organic wastewater;

(3) It is classified by industrial sector or production process that produces wastewater, such as coking wastewater, metallurgical wastewater, pharmaceutical wastewater, food wastewater, etc.

⒉ The main pollutant in wastewater

(1) Industrial wastewater discharged without treatment;

(2) Domestic sewage discharged without treatment;

(3) Farmland sewage caused by heavy use of chemical fertilizers, pesticides and herbicides;

(4) Industrial waste and domestic waste piled up in the river;

(5) Deforestation and soil erosion;

(6) Mine sewage is produced due to excessive exploitation.

Second, the main source of groundwater pollution

In summary, groundwater pollution sources can be divided into the following points:

1. Industrial pollution

Industrial "three wastes" (waste water, waste gas, waste residue) is one of the main factors of groundwater pollution. Industrial wastewater such as industrial electroplating wastewater, industrial pickling wastewater, smelting industry wastewater, light industry wastewater and petrochemical organic wastewater are discharged into urban sewers, rivers, lakes and oceans or directly into ditches and large dikes without treatment, resulting in groundwater chemical pollution.

Industrial effluents and wastes can increase the concentration of organic and inorganic compounds in groundwater. Industrial wastewater is an important source of water pollution. It has the characteristics of large quantity, wide area, complex composition, high toxicity, difficult to purify and treat.

⒉ mine pollution

It refers to the influence and harm caused by various factors on the environment in the process of mining. Among them are mainly mine drainage, ore and waste rock piles produced leached water, mining industrial and domestic wastewater, ore dust, coal emission and SO2 and radiation of radioactive substances, which contain a large number of harmful substances, seriously harm the mine environment and human health.

Agricultural pollution

Groundwater pollution caused by agricultural activities mainly includes livestock manure, residual pesticides, fertilizers in soil, decomposition of animal and plant remains, and unreasonable sewage irrigation. Agricultural activities can promote the oxidation of soil organic matter, such as the oxidation of organic nitrogen to inorganic nitrogen (mainly nitrate nitrogen), and the infiltration of water into groundwater, causing a large area of shallow underground water quality deterioration, among which the most important is the increase of nitrate nitrogen NO3- and the pollution of pesticides and fertilizers.

Fertilizer and manure applied in agriculture can cause a wide range of groundwater nitrate levels to increase. In pesticide sewage, the content of organic matter, plant nutrients and pathogenic microorganisms is high, and the content of pesticides and fertilizers is high. According to relevant data, on 100 million hectares of arable land and 2.2 million hectares of grassland, 1.104,900 tons of pesticides are used every year. China is one of the countries with the most serious soil and water loss in the world, with the annual loss of about 5 billion tons of topsoil, resulting in a large number of pesticides and fertilizers flowing into rivers, rivers, lakes and reservoirs with the topsoil, and the subsequent loss of nitrogen, phosphorus and potassium nutrients, causing 2/3 of lakes to be affected by different degrees of eutrophication pollution, resulting in abnormal reproduction of algae and other organisms. It causes the change of water transparency and dissolved oxygen, resulting in the deterioration of water quality.

Domestic pollution.

Domestic sewage and domestic garbage can cause the total salinity, total hardness, nitrate and chloride content of groundwater to increase, and sometimes cause pathogen pollution.

One side is the continuous development of the economy, a large number of plastic, metal, batteries and other indigestible new waste appeared; On the one hand, the lack of infrastructure and control has made the direct discharge of rural sewage and garbage increasingly serious. As domestic waste is washed by the sun and rain and surface runoff, its dissolved matter will slowly penetrate into the ground and pollute the groundwater.

Domestic pollution sources are mainly all kinds of detergents and sewage, garbage, feces used in urban life, mostly non-toxic inorganic salts, domestic sewage contains more nitrogen, phosphorus, sulfur, disease-causing bacteria. According to the survey, about 1/3 of China's industrial wastewater and more than 90% of domestic sewage are discharged into the waters without treatment every year, the country has more than 1,200 rivers monitored, more than 850 are polluted, more than 90% of urban waters are also polluted, resulting in the extinction of fish and shrimp in many river sections, and only 32.2% of the rivers meet the national grade I and II water quality standards. Pollution is moving from shallow layers to deep layers. Groundwater and seawater are also being polluted, and the amount of water we can drink and use is unknowingly decreasing.