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.

5. Seawater intrusion and flooding in coastal areas

Seawater flooding is the phenomenon of seawater intrusion into freshwater aquifers. The main cause of saltwater invasion is the overexploitation of fresh water from groundwater. Due to the excessive exploitation of underground freshwater, the freshwater - seawater interface on coastal or island is in an unbalanced state. In the northern coastal areas of China, there has been a continuous drought for many years, the rainfall is low, and the groundwater supply is reduced, but the water demand for industry and agriculture is constantly increasing, and the underground fresh water is "beyond the income", resulting in seawater intrusion and backflow.

Three, the main hazards of water pollution

Increasingly aggravated water pollution has posed a major threat to human survival and security, and has become a major obstacle to human health, economic and social sustainable development. According to the survey of the world authority, in developing countries, 80% of all kinds of diseases are spread because of drinking unsanitary water, and at least 20 million people die every year because of drinking unsanitary water, so water pollution is called "the world's number one killer".

Water pollution affects industrial production, increases equipment corrosion, affects product quality, and even makes production impossible. Water pollution also affects people's lives, destroys ecology, directly endangers people's health, and does great damage.

A. Harm to human health

After water pollution, through drinking water or the food chain, pollutants enter the human body, causing acute or chronic poisoning. Arsenic, chromium, ammonium, benzo (a) pyrene, etc., can also cause cancer. Water contaminated with parasites, viruses or other pathogens can cause a variety of infectious and parasitic diseases.

Water polluted by heavy metals is harmful to people's health. Cadmium contaminated water, food, human diet, will cause kidney, bone lesions, ingestion of cadmium sulfate 20 mg, will cause death. Poisoning from lead, causing anemia, confusion. Hexavalent chromium is highly toxic, causing skin ulcers and carcinogenic effects. Acute or chronic poisoning can occur when drinking water containing arsenic. Arsenic inhibits or inactivates many enzymes, resulting in metabolic disorders, skin keratinization, and skin cancer.

Organophosphorus pesticides can cause nerve poisoning, and organochlorine pesticides can accumulate in fat, causing harm to the endocrine, immune and reproductive functions of humans and animals. Most of the polycyclic aromatic hydrocarbons have carcinogenic effects. Cyanide is also a highly toxic substance. After entering the blood, it binds to the pigment oxidase of cells, which interrupts breathing and causes respiratory failure and asphyxia.

We know that 80 percent of the world's diseases are related to water. Typhoid fever, cholera, gastroenteritis, dysentery, infectious hepatitis are the five major human diseases, all caused by unclean water.

⒉ Harm to industrial and agricultural production

After water pollution, industrial water must be invested in more treatment costs, resulting in the waste of resources and energy, food industry water requirements are more stringent, water quality is unqualified, will make production halt. This is also the factor of low efficiency and poor quality of industrial enterprises.

The use of sewage in agriculture has reduced crop production, reduced the quality of crops, and even harmed people and livestock. Large areas of farmland have been polluted, reducing the quality of soil.

The consequences of Marine pollution are also very serious, such as oil pollution, causing the death of seabirds and Marine life.

The harm of water eutrophication

Under normal conditions, oxygen has a certain solubility in water. Dissolved oxygen is not only a condition for the survival of aquatic organisms, but also participates in various REDOX reactions in water to promote the transformation and degradation of pollutants, which is an important reason for the self-purification ability of natural water bodies. The discharge of domestic sewage containing a large amount of nitrogen, phosphorus and potassium, the degradation of a large number of organic matter in the water and the release of nutrient elements, promote algae clumping in the water, the growth of plants, the poor ventilation of the water, the decline of dissolved oxygen, and even the appearance of anaerobic layer. It causes a large number of aquatic plants to die, the water surface is black, the water body is smelly and forms a "dead lake", "dead river", "Dead Sea", and then becomes a swamp, but also can lead to red tide phenomenon. This phenomenon is called water eutrophication. The eutrophication water is smelly, dark in color, and has many bacteria. The quality of this water is poor, and it cannot be directly used.

Methods to prevent water pollution

⒈ Strengthen the protection of intakes of drinking water sources

The relevant departments shall delimit the water source areas, set up billboards in the areas and strengthen the greening of water intake outlets. Regularly organize personnel to inspect, eliminate pollution from the root, to achieve the purpose of treating both symptoms and root causes.

⒉ Establish urban sewage treatment system

Speeding up the construction of urban sewage treatment plant plays a very important role in improving the water environment. At present, with the increase of urban population and the improvement of residents' living standards, the discharge of urban wastewater is constantly increasing, but the urban sewage treatment plant has not increased correspondingly, which will inevitably lead to the decline of water environment quality. Therefore, it is urgent to build more sewage treatment plants.

C. Strengthen citizens' awareness of water resources protection

To improve the environment, it is not only necessary to manage it, but more importantly, to enhance residents' awareness of environmental protection through all aspects of publicity. Strengthen the education of young people to protect water resources, shoot educational films, do publicity activities, so that every flower in China in the future has the good character of saving and protecting water resources. Residents' awareness of environmental protection is enhanced, the behavior of damaging the environment will naturally decrease, and the problem of massive pollution of water resources will gradually decrease.

Realize waste water resource utilization

With the development of economy, industrial wastewater discharge will increase, if only pay attention to the end of treatment, it is difficult to achieve the purpose of improving the current water pollution situation, so we must realize the utilization of wastewater resources. In order to control the development of water pollution, industrial enterprises must also actively control water pollution, especially the discharge of toxic pollutants must be treated separately or pre-treated.

5. Strengthen the treatment of urban domestic sewage, industrial wastewater and initial rainwater

With the acceleration of the urbanization process, the discharge of urban domestic sewage and industrial wastewater is more and more large, and there are many problems in the pipe network constructed in the past, and it is impossible to effectively distinguish and treat domestic sewage, industrial wastewater, early rainwater and middle and late rainwater. Science and technology can be used to rationally transform the existing pipe network, so that sewage is discharged into the sewage treatment plant, and clean rainwater is directly discharged into the natural water body, so as to effectively reduce the pollution of rivers and lakes.

With the adjustment of industrial layout, urban layout and the construction and improvement of urban sewer network, the centralized treatment of urban sewage can be gradually realized, so that urban sewage treatment and industrial wastewater treatment can be combined.

Pictures of water purification

Filtration - precipitation (alum) - odor removal with activated carbon, color removal - disinfection (chlorine, bleach powder). There may be secondary pollution in the process of water pipe transmission, so it is necessary to boil sterilization when drinking, and use a clean cup. Families with conditions can install home health water dispensers

A small amount of it creates landfills

A small amount of landfills can be created so that waste water and gases can be treated and then discharged into rivers. Because landfills cover a large area and waste land resources, they should be created in small quantities.

Reduce water consumption

At present, the use of water resources in our country feels the tension of water resources on the one hand, and the waste is very serious on the other hand. Compared with the industrial developed countries, many units of water consumption in China is much higher. Large water consumption not only causes waste of water resources, but also is an important cause of water environment pollution.

Through the technological transformation of enterprises, the implementation of cleaner production, reducing the water consumption per unit product, multi-use of one water, and improving the reuse rate of water have been proved to be effective in practice.

⒐ Industrial restructuring

The natural purification capacity of water body is limited, and reasonable industrial layout can make full use of the natural capacity of the natural environment, turn the vicious circle into a virtuous circle, and play a role in economic development and pollution control. Shut down, stop, and transfer those enterprises that consume a lot of water, pollute heavily, and control pollution at a high cost. It is also necessary to adjust the agricultural structure that consumes a lot of water, especially in arid and semi-arid areas to reduce rice planting area, and take the road of water-saving agriculture and sustainable development.

⒑ Control pollution from non-point agricultural sources

Agricultural non-point source pollution includes rural living source, agricultural non-point source, livestock and poultry farming and aquaculture pollution. It is more difficult to solve non-point source pollution than industrial pollution and domestic sewage in large and medium-sized cities, and it needs to be controlled through comprehensive prevention and control and ecological agriculture demonstration projects.

⒒ Develop new water sources

China's industrial, agricultural and domestic water saving potential is not small, we need to do a good job of water saving, reduce waste, to reduce the unit of GDP water consumption. The implementation of the South-to-North Water diversion project plays an important role in alleviating the severe water shortage in Shandong and North China. The construction of reservoirs, exploitation of groundwater and purification of seawater can alleviate the increasing pressure of water use, but the impact on the ecological environment and social environment should be fully considered when the construction of reservoirs and exploitation of groundwater.

⒓ We will strengthen planning and management of water resources

Water resources planning is the main component of regional planning, urban planning, industrial and agricultural development planning, and should be carried out simultaneously with other planning.

Rational development must also be based on the supply and demand of water, the implementation of a quota of water, and the unified development and utilization of surface water, groundwater and sewage resources, to prevent the depletion of surface water sources and the decline of groundwater levels, and to effectively achieve reasonable development, comprehensive utilization, active protection and scientific management.

Use the market mechanism and economic leverage to promote the conservation of water resources, and promote the management of sewage and its resources. In order to effectively control water pollution, the management should gradually transition from concentration management to total control management. Its main measures are:

(1) Strengthen the monitoring of water quality;

(2) The three industrial wastes should be discharged after treatment;

(3) Rational use of pesticides and fertilizers;

(4) It is forbidden to use a large amount of phosphorus-containing laundry detergent;

(5) Strengthen soil and water protection and plant trees.