When it comes to industrial wastewater, many people don't have a clear concept. Most of us think that industrial wastewater is sewage discharged by some companies or enterprises. Strictly speaking, this definition is not accurate. Industrial wastewater refers to wastewater, sewage and waste liquid generated in the industrial production process, which contains industrial production materials, intermediates and products lost with water, and pollutants generated in the production process.

Common industrial wastewater mainly includes the following categories:

1. Pesticide wastewater There are many varieties of pesticides, and the water quality of pesticide wastewater is complex. Its main characteristics are: high concentration of pollutants, high toxicity and stench. Therefore, pesticide wastewater pollutes the environment very seriously.

2. Phenolic wastewater Phenolic wastewater mainly comes from industrial departments such as coking plants, gas plants, petrochemical plants, insulation materials plants, and petroleum cracking to produce ethylene, synthetic phenol, polyamide fibers, synthetic dyes, organic pesticides and phenolic resin production processes. Phenolic wastewater mainly contains phenolic compounds, which are a kind of protoplasmic poison that can coagulate proteins.

3.Mercury-containing wastewater Mercury-containing wastewater mainly comes from non-ferrous metal smelters, chemical plants, pesticide plants, paper mills, dye plants and thermal instrumentation plants. The toxicity of various mercury compounds varies greatly, such as methylmercury. Methylmercury is easily absorbed by the human body, not easy to degrade, excreted very slowly, and easily accumulated in the brain.

4. Heavy metal wastewater Heavy metal wastewater mainly comes from wastewater discharged by mining, smelting, electrolysis, electroplating, pesticides, medicines, paints, pigments and other enterprises. The types, contents and existence forms of heavy metals in wastewater vary with different production enterprises.

5. Metallurgical wastewater The main characteristics of metallurgical wastewater are large water volume, many types, and complex and changeable water quality. According to the source and characteristics of wastewater, there are mainly cooling water, pickling wastewater, washing wastewater (dust removal, coal gas or flue gas), slag flushing wastewater, coking wastewater, and wastewater condensed, separated or overflowed from production.

6. Papermaking industrial wastewater Papermaking wastewater mainly comes from the two production processes of pulping and papermaking in the papermaking industry. Pulping is to separate the fibers from plant raw materials, make pulp, and then bleach; papermaking is to dilute, shape, press, and dry the pulp to make paper. Both processes discharge a large amount of wastewater.

There are many types of industrial wastewater, and I will not list them one by one here. With the rapid development of industry, the types and quantities of wastewater are also increasing rapidly, and the pollution of water bodies is becoming more and more widespread, which seriously threatens human health and safety. Compared with developed Western countries, my country's treatment of wastewater pollution started relatively late, resulting in the current situation of industrial wastewater pollution in my country is not optimistic. So what are the hazards of industrial wastewater? What methods are currently used to treat industrial wastewater?

Hazards of industrial wastewater

1. Industrial wastewater flows directly into channels, rivers, and lakes, polluting surface water. If it is highly toxic, it will cause the death or even extinction of aquatic plants and animals;

2. Industrial wastewater may also penetrate into groundwater, pollute groundwater, and then pollute crops;

3. If the surrounding residents use polluted surface water or groundwater as domestic water, it will endanger their health and even cause death;

4. Industrial wastewater infiltrates into the soil, causing soil pollution and affecting the growth of plants and microorganisms in the soil;

5. Some industrial wastewater also has an unpleasant odor, polluting the air;

6. Toxic and harmful substances in industrial wastewater will remain in the body due to the ingestion and absorption of plants and animals, and then reach the human body through the food chain, causing harm to the human body.

Although my country's industrial wastewater treatment started late, on the basis of learning from the experience of advanced foreign treatment technologies, my country has introduced and developed a large number of new wastewater treatment technologies.

Membrane technology

Commonly used membrane separation methods include microfiltration, nanofiltration, ultrafiltration and reverse osmosis. Since membrane technology does not introduce other impurities during the treatment process, it can achieve the separation of macromolecules and small molecules, so it is often used to recover various macromolecular raw materials, such as using ultrafiltration technology to recover polyvinyl alcohol slurry from printing and dyeing wastewater. Iron-carbon micro-electrolysis treatment technology Iron-carbon micro-electrolysis is a good process for treating wastewater using the Fe/C galvanic cell reaction principle, also known as internal electrolysis, iron filings filtration, etc. Iron-carbon micro-electrolysis is a comprehensive effect of electrochemical redox, electrochemical enrichment of flocs, coagulation of electrochemical reaction products, adsorption of new flocs and bed filtration, among which redox and electro-attachment and coagulation are the main effects. Ozone oxidation Ozone is a strong oxidant that reacts quickly with reduced pollutants, is easy to use, does not produce secondary pollution, and can be used for sewage disinfection, decolorization, deodorization, removal of organic matter and reduction of COD. Magnetic separation technology Magnetic separation technology is a new type of water treatment technology developed in recent years that uses the magnetism of impurity particles in wastewater for separation. For non-magnetic or weakly magnetic particles in water, magnetic inoculation technology can make them magnetic. There are three ways to apply magnetic separation technology to wastewater treatment: direct magnetic separation, indirect magnetic separation and microbial-magnetic separation.

SCWO (supercritical water oxidation) technology

SCWO uses supercritical water as a medium to homogeneously oxidize and decompose organic matter. Organic pollutants can be decomposed into inorganic small molecules such as CO2 and H2O in a short time, while sulfur, phosphorus and nitrogen atoms are converted into sulfate, phosphate, nitrate and nitrite ions or nitrogen gas respectively. The United States lists the SCWO method as the most promising waste treatment technology in the field of energy and environment.