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Industrial wastewater treatment equipment
Author：hngoob Renew time：2020-02-22
Industrial wastewater refers to process wastewater, waste liquid and domestic sewage generated in industrial production activities, which contain industrial production materials, intermediate products, by-products and pollutants generated in the production process. The following are the sources and treatment methods of ten common industrial wastewater: Heavy metal wastewater is mainly from mining, smelting, electrolysis, electroplating, pesticide, medicine, paint, pigment and other enterprises.
Treatment methods for heavy metal wastewater can generally be divided into two categories:
(a) heavy metals in the wastewater in a dissolved state are converted into insoluble metal compounds or elements, which are removed from the wastewater through precipitation and floating, and neutralization precipitation, sulfide precipitation, floating separation, electrolytic precipitation, diaphragm electrolysis and the like can be used;
(b) Concentrating and separating heavy metals in wastewater without changing their chemical forms, such as reverse osmosis, electrodialysis, evaporation and ion exchange. cyanide-containing waste Cyanide-containing wastewater mainly comes from electroplating, coal gas, coking, metallurgy, metal processing, chemical fiber, plastic, pesticide, chemical industry and other departments, and is a kind of industrial wastewater with great toxicity.
Treatment methods of cyanide-containing wastewater include alkaline chlorination, electrolysis, pressurized hydrolysis, biochemical method, biological iron method, ozone treatment method, air stripping method, etc. phenolic effluent Phenol-containing wastewater mainly comes from the production processes of petroleum cracking to produce ethylene, synthetic phenol, polyamide fiber, synthetic dye, organic pesticide and phenolic resin. For phenol-containing wastewater with different concentrations:
(a) High-concentration phenol-containing wastewater (mass concentration higher than 1000mg/L):
phenol must be recovered before treatment;
(b) Low-concentration phenol-containing wastewater (mass concentration less than 1000mg/L):
phenol can be concentrated and recycled. Methods for recovering phenol include solvent extraction, steam stripping, adsorption and closed circulation.
Papermaking wastewater
Papermaking wastewater mainly comes from two production processes of pulping and papermaking in papermaking industry. Both processes discharge a large amount of wastewater. Papermaking wastewater has complex components and poor biodegradability, and belongs to industrial wastewater which is difficult to treat.
Flotation method is usually used to recover fibrous solid substances in white water, combustion method is used to recover sodium salts in black water, neutralization method is used to adjust pH value of wastewater, coagulation sedimentation is used to remove suspended solids in wastewater, chemical precipitation method is used to decolorize, aerobic activated sludge treatment method and fungus treatment method can also generally obtain good results. In addition, reverse osmosis, ultrafiltration, electrodialysis and other treatment methods are also used. Henan gubo industry co., ltd. Printing and dyeing wastewater
Printing and dyeing wastewater contains dyes, slurries, auxiliaries, oils, acids and bases, fiber impurities, sand substances, inorganic salts, etc.
It has the characteristics of large amount of water, high content of organic pollutants, large alkalinity, large changes in water quality, etc. Harmless treatment of printing and dyeing wastewater can be divided into:
(a) Physical treatment: precipitation, adsorption, etc.
(b) Chemical treatment: neutralization, coagulation, oxidation, etc.
(c) Biological treatment methods: activated sludge, biological rotating disc, biological rotating drum, biological contact oxidation method, etc.
Chemical industry wastewater Chemical industry wastewater mainly comes from production wastewater discharged from petrochemical industry, coal chemistry industry, acid and alkali industry, chemical fertilizer industry, plastic industry, pharmaceutical industry, dye industry, rubber industry, etc. Chemical industry wastewater is generally treated in three levels:
A) primary treatment: mainly separate suspended solids, colloid, floating oil or heavy oil in water, and adopt natural precipitation, floating and other methods;
B) secondary treatment: mainly removing biodegradable organic solutes and some colloids, usually by biological method;
C) tertiary treatment: mainly to remove organic pollutants and dissolved inorganic pollutants that are difficult to biodegrade in wastewater, and commonly used methods include activated carbon adsorption method and ozone oxidation method. Wastewater from food industry Wastewater from food industry is characterized by high content of organic substances and suspended substances, easy corruption and generally no great toxicity.
In general, it is appropriate to adopt biological treatment method for food industry wastewater. For example, two-stage aeration tank or two-stage biological filter tank, or multi-stage biological rotary table, or combination of two biological treatment devices, or anaerobic-aerobic series biological treatment system can be adopted due to high requirements on effluent quality or high organic content in wastewater.
Metallurgical wastewater Metallurgical wastewater is classified according to the source and characteristics of wastewater, mainly including cooling water, pickling wastewater, washing wastewater, slag flushing wastewater, coking wastewater and wastewater condensed, separated or overflowed from production.
Metallurgical wastewater is usually treated by oxidation-reduction method, i.e. toxic and harmful substances dissolved in wastewater are converted into non-toxic and harmless new substances through oxidation-reduction reaction. In redox reactions:
(1) when toxic and killed substances are used as reducing agents, oxidants such as air, ozone, chlorine, sodium hypochlorite and the like need to be added;
(2) When toxic and harmful substances are used as oxidizing agents, reducing agents such as ferrous sulfate, ferrous chloride and zinc powder need to be added.
Mineral processing wastewater Mineral processing wastewater includes mineral processing process drainage, tailings pond overflow water and mine drainage, and contains many kinds of harmful substances. The pollutants in mineral processing wastewater mainly include suspended solids, acid and alkali, heavy metals, mineral processing agents, chemical oxygen consumption substances and other pollutants.
Different treatment methods can be adopted for pollutants in wastewater. Suspended matters are mainly pre-precipitated, coagulated/precipitated. Acid-base wastewater is neutralized with each other. Heavy metal ions can be co-precipitated, adsorbed and ion exchanged. Chemical oxygenates can be coagulated/precipitated, biodegradable, advanced oxidation, adsorption, etc. Acid and alkali wastewater Acid wastewater mainly comes from iron and steel plants, chemical plants, dye plants, electroplating plants and mines. Alkaline wastewater mainly comes from printing and dyeing factories, leather factories, paper mills, oil refineries, etc. In addition to acid and alkali, acid and alkali wastewater often contains acid salts, basic salts, other inorganic substances and organic substances, which are highly corrosive.
For acid and alkali wastewater with different concentrations, the treatment methods are also different:
A) high concentration acid and alkali waste water should be given priority to recycling, according to the water quality, water quantity and different process requirements, factory or regional scheduling, reuse as much as possible;
B) low concentration acid and alkali wastewater shall be neutralized, such as acid and alkali wastewater neutralizing each other or waste alkali (slag) neutralizing acid wastewater, waste acid neutralizing alkaline wastewater, etc.
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