Several common industrial wastewater treatments (2)

(5) Heavy metal wastewater treatment Heavy metal wastewater mainly comes from electrolysis, electroplating, mining, pesticides, medicine, smelting, paint, pigments and other production processes
.
The treatment of heavy metal wastewater can generally be divided into two categories: one is to convert heavy metals in a dissolved state into insoluble metal compounds or elements, which are removed from the wastewater by precipitation and floatation.

(6) Cyanide-containing wastewater treatment Cyanide-containing wastewater mainly comes from electroplating, chemical fiber, plastics, pesticides, chemicals, gas, coking, metallurgy, metal processing and other sectors
.
Cyanide-containing wastewater is a highly toxic industrial wastewater.

(7) Treatment of mercury-containing wastewater The mercury-containing wastewater mainly comes from non-ferrous metal smelters, paper mills, dye plants, chemical plants, pesticide plants, and thermal instrumentation plants
.
The methods for removing inorganic mercury in wastewater include sulfide precipitation method, chemical coagulation method, activated carbon adsorption method, metal reduction method, ion exchange method and microbial method

(8) Food industry wastewater treatment The main pollutants in food industry wastewater include solid substances floating in the wastewater, such as vegetable leaves, peels, minced meat, poultry feathers, etc.
; substances suspended in the wastewater include grease, protein , starch, and colloidal substances and the like; acid dissolved in the waste water, bases, salts, sugars and the like; material entrained silt and other organic substances; drugs and other pathogens
.
In addition to proper pretreatment according to the characteristics of water quality, the wastewater treatment in the food industry should generally adopt biological treatment

(9) Printing and dyeing industrial wastewater treatment The amount of printing and dyeing industrial wastewater is large, based on comprehensive consideration of recycling and harmless treatment
.
Recycling, such as the diversion of bleaching and smelting wastewater and dyeing and printing wastewater.

(10) Chemical industry wastewater treatment Chemical industry wastewater mainly comes from production wastewater discharged from the chemical industry, coal industry, acid and alkali industry, fertilizer industry, plastic industry, pharmaceutical industry, dye industry, and rubber industry
.
Chemical industry wastewater treatment should be selected according to water quality and requirements

(11) Acid-base wastewater treatment Acidic wastewater mainly comes from steel plants, chemical plants, dye plants, electroplating plants and mines, etc.
, which contain various harmful substances or heavy metal salts
.
The mass fraction of acid varies greatly, the low is less than 1%, and the high is greater than 10%

(12) The treatment of beneficiation wastewater comes from industries such as mining technology and tailings
.
The main harmful substances are heavy metal ions and mineral processing agents

(13) Metallurgical wastewater treatment comes from the production process of metallurgy, chemical industry, dyes, electroplating, mining and machinery industries
.

There are many types of metallurgical wastewater, large water volume and complex water quality
.
Classified according to the source and characteristics of wastewater, there are mainly phenol washing wastewater, cooling water, pickling wastewater, washing wastewater (dust removal, gas or flue gas), slag washing wastewater, coking wastewater, and wastewater that is condensed, separated or overflowed from production
.
Because the metallurgical industry wastewater temperature is higher than normal temperature, the wastewater contains suspended solids (sludge, oil) and dissolved chemical substances, so the steps of wastewater treatment usually include wastewater cooling, suspended solids removal, and dissolved substances extraction
.
According to the characteristics of different pollutants, the treatment methods of metallurgical industry wastewater include physical treatment (gravity centrifugation, screening and retention, magnetic separation, air flotation), chemical treatment (coagulation neutralization, redox, extraction, Air stripping, stripping, adsorption, ion exchange, electrodialysis, reverse osmosis, etc.
), physical and chemical treatment (adsorption separation, extraction, stripping, etc.
), biological treatment (aerobic biological treatment, anaerobic biological treatment, etc.
)
.
The development of new treatment processes and technologies suitable for the characteristics of metallurgical wastewater, such as the treatment of iron and steel wastewater by magnetic methods, has the advantages of high efficiency, less land occupation, and convenient operation and management
.