This paper introduces the water quality characteristics and treatment difficulties of 17 kinds of wastewater, including printing and dyeing wastewater, hospital wastewater, electroplating wastewater, paper mill wastewater, tannery wastewater, monosodium glutamate wastewater, pesticide wastewater, electrophoresis wastewater, washing wastewater, power plant wastewater, printing wastewater, beer wastewater, dairy wastewater, circuit board wastewater, starch wastewater, slaughterhouse wastewater and coking wastewater.
1. Printing and dyeing wastewater
Printing and dyeing wastewater is difficult to treat because of its large amount of water, high content of organic pollutants, deep chroma, high alkalinity and great changes in water quality. In the pretreatment stage (including singeing, desizing, scouring, bleaching and mercerizing), desizing wastewater, scouring wastewater, bleaching wastewater and mercerizing wastewater are discharged. In the dyeing process, dyeing wastewater is discharged. In the printing process, printing wastewater and soap wastewater are discharged. In the finishing process, finishing wastewater is discharged. Printing and dyeing wastewater is a mixture of all kinds of wastewater, or a comprehensive wastewater except bleaching wastewater.
2. Hospital Wastewater
Hospital sewage refers to the sewage discharged by hospitals (general hospitals, professional hospitals and other types of hospitals) to the natural environment or urban pipelines. The water quality varies with the nature, scale and location of different hospitals. The amount of sewage discharged from each bed is about 200-1000l per day. The main pollutants in hospital sewage are pathogens (parasite eggs, pathogens, viruses, etc.), organic matter, floating and suspended solids, radioactive pollutants, etc. the total amount of bacteria in untreated raw sewage is more than 10 ^ 8 / ml.
3. Electroplating wastewater
The composition of electroplating wastewater is very complex. In addition to cyanide (CN -) containing wastewater and acid-base wastewater, heavy metal wastewater is a kind of wastewater with great potential harm to electroplating industry. According to the heavy metal elements in heavy metal wastewater, it can be divided into chromium (CR) wastewater, nickel (Ni) wastewater, cadmium (CD) wastewater, copper (Cu) wastewater, zinc (Zn) wastewater, gold (AU) wastewater, silver (Ag) wastewater, etc.
4. Papermaking wastewater
Papermaking industry is one of the industries with high energy and material consumption and serious environmental pollution. Its pollution characteristics are large amount of wastewater discharge, high content of COD and SS, and serious chroma.
The main problems to be solved in wastewater treatment: the concentration of SS and COD in papermaking wastewater is high, and COD is composed of insoluble COD and soluble COD. Generally, the insoluble cod accounts for the majority of the total COD. When SS in wastewater is removed, the vast majority of insoluble cod is removed at the same time. Therefore, the main problem to be solved is to remove SS and cod.
5. Tannery wastewater
At present, the production of leather industry generally includes degreasing, liming, unhairing, softening, tanning, dyeing, drying, finishing and so on. In the process, a variety of chemicals need to be added, so that the waste water contains oil, collagen, animal and plant fibers, organic and inorganic solids, sulfide, chromium, salts, surfactants, etc Dyes and other pollutants and toxic substances. The water quality characteristics of tannery wastewater are: CODcr 3000-4000mg / L, BOD5 1000-2000mg / L, SS 2000-4000mg / L, pH 8-11.
The wastewater mainly comes from preparation before tanning, tanning and other wet processing sections. Degreasing wastewater, liming and unhairing wastewater and chrome tanning wastewater are the most polluted. These three kinds of wastewater account for about 50% of the total amount of wastewater, but they contain the vast majority of pollutants. The mass fraction of various pollutants in the total amount is: CODcr 80%, bod575%, ss70%, sulfide 93%, sodium chloride 50%, chromium compounds 95%.
The characteristics of tannery wastewater are as follows：
①Water quality and quantity fluctuate greatly；
②Good biodegradability；
③The concentration of suspended solids is high, which is easy to corrupt and produces a large amount of pollution；
④ The wastewater contains toxic compounds such as S2 - and chromium.
6. Monosodium glutamate wastewater
The high concentration organic wastewater produced in the production of monosodium glutamate mainly refers to the mother liquor discharged from the fermentation broth after extracting glutamic acid. The water quality of this kind of wastewater has the characteristics of "five high and two low", that is, high COD, high BOD, high sulfate, high NH3-N, high cell content, low temperature and low pH. Monosodium glutamate wastewater is a kind of industrial wastewater which is difficult to treat at present. Bathing wastewater is an important part of urban wastewater, which has high turbidity, low organic matter content, large water volume and high phosphorus content.
7. Pesticide wastewater
The concentration of pollutants in pesticide wastewater is high, COD (chemical oxygen demand) can reach tens of thousands of mg per liter; the toxicity is high, in addition to pesticides and intermediates, the wastewater also contains phenol, arsenic, mercury and other toxic substances, as well as many substances that are difficult to biodegrade; there is a stench, which is irritating to human respiratory tract and mucous membrane; the water quality and quantity are unstable.
8. Electrophoresis wastewater
The reason why the waterborne resin of electrophoretic paint can be diluted and dispersed with water is that there are a certain number of hydrophilic groups in the polymer molecular chain. For example, it contains carboxyl (- COOH), hydroxyl (- OH), ether (- O -), amino (- NH2), etc. According to the charge of water dispersing resin, it can be divided into two types: the water-based resin with carboxyl group (- COOH) is anodic electrophoretic paint (or anion electrophoretic paint), and the water-based resin with amino group (- NH2) is cathodic electrophoretic paint (or cation electrophoretic paint). The two most important electrophoretic properties of cathodic electrophoretic coating are the permeability and coulomb efficiency.
9. Laundry wastewater
The main pollutant in laundry wastewater is anionic surfactant. After entering the water body, it combines with other pollutants to form certain dispersed colloidal particles. LAS and other surfactants in the wastewater exist as dispersions and colloidal particles. The organic components are mainly surfactants, which mainly have the following characteristics：
1）Anionic surfactant, the main pollutant in wastewater, combines with other pollutants to form certain dispersed colloidal particles after entering the water body. LAS and other surfactants in wastewater exist in the form of dispersion and colloidal particle surface adsorption, which has a great impact on the physicochemical and biochemical properties of wastewater.
2）The quality of wastewater fluctuates greatly, and the regularity of discharge is poor. Most of the surfactant wastewater is alkaline, and the pH value is between 8 and 11. Some of the Las content in wastewater is as high as several milligrams per liter, such as wool washing wastewater; Some are only ten milligrams per liter, such as washing waste water. At present, the load of LAS and other anionic surfactants in the wastewater from synthetic detergent factories in China is generally 10 ~ 60, the higher is 135, and the COD difference can also change from several hundred to tens of thousands or even tens of thousands.
3）Toxicity and harm to water -- Las in wastewater itself has certain toxicity and chronic toxicity to animals and human body. Las can degrade the speed of oxygen transfer in water, and even make the water lack of oxygen, corrupt and hinder the process of water self purification. When the content of phosphate is high, it may cause duckweed formation.
10. Power plant wastewater
Power plant wastewater mainly includes the following kinds of flushing water and ash flushing water. Domestic sewage circulating water, concentrated water and resin regeneration wastewater mainly contain oil, suspended solids, scale inhibitor, bactericide, hardness, ash, high content of salt and part of organic matter, high concentration of sulfite, sulfate, fluoride and heavy metals, as well as certain heat sources.
11. Printing wastewater
Printing wastewater contains a large number of acrylic macromolecules. If it is directly discharged into the urban sewage pipe network without treatment, it will have a great impact on the sewage treatment process, destroy the biochemical treatment system and pollute the water environment. The amount of water is relatively small, while the CODcr is very high (up to 20000), there are a certain amount of suspended solids, bacteria and dissolved substances, and the turbidity and chromaticity are high.
12. Brewery Wastewater
Beer wastewater mainly comes from malting workshop (malting wastewater), saccharification workshop (saccharification, filtration and washing wastewater), fermentation workshop (fermentation tank washing, filtration and washing wastewater), filling workshop (bottle washing, sterilization wastewater and beer from broken bottles), and production cooling wastewater.
Beer industry wastewater mainly contains sugars, alcohols and other organic matter. The concentration of organic matter is high. Although it is non-toxic, it is easy to corrupt. A large amount of dissolved oxygen will be consumed when it is discharged into the water body, causing serious harm to the water environment. The water quality and quantity are different in different seasons, and the organic matter content is also at the peak when the flow is at the peak. Domestic brewery wastewater: CODcr content: 1000 ~ 2500mg / L, BOD5 content: 600 ~ 1500 mg / L, the wastewater has high biodegradability, and contains a certain amount of Kjeldahl nitrogen and phosphorus.
13. Dairy wastewater
Dairy wastewater is the wastewater discharged from the production of condensed milk, cheese, cream, milk beverage, ice cream and dairy snacks. The waste water mainly comes from the cleaning water of containers and equipment, and the main component contains raw materials of products. Among them, the milk processing plant contains 0.2% raw milk, bod20-300mg / L, with low pollution, while the cheese and cream processing wastewater has high pollution level, cod is 3000 mg / L, BOD is 2400 mg / L, total nitrogen (TN) is 90 mg / L, total phosphorus (TP) is 16 mg / L, oil is 200 mg / L, suspended solids is 600 mg / L, and the raw materials in the wastewater, such as cream, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk, milk Condensed milk should be recycled as a by-product and its loss should be reduced in the production process.
In the process of dairy processing, the cleaning and disinfection water of containers, equipment and pipes constitutes the high concentration wastewater of dairy processing, and its COD value can exceed 20000mg / L. Generally, it is more than 5000mg / L, and the amount of wastewater is about 1.0m3 per ton of raw milk. With the change of production variety, output, factory management and other factors, the amount of wastewater changes. The surface water and other water (such as office water, domestic water, etc.) in the washing workshop of dairy factory constitute low concentration wastewater. Generally, the COD value is below 10oomg / L, and about 3-4m3 low concentration wastewater is produced for each ton of raw milk.
Generally, the COD of wastewater discharged by liquid milk and milk powder production enterprises is about 1500-300omg / L, and the COD of wastewater discharged by dairy products enterprises such as yogurt, cream, ice cream, ice cream, cheese, etc. is generally 4000-7000mg / L.
The main pollution components of dairy wastewater are milk protein (such as casein and whey protein), lactose, milk fat, various minerals contained in raw milk, acid and alkali used for cleaning equipment, pipes and containers, etc. the pH value of wastewater is generally 6.5-7.0.
14. PCB wastewater
PCB wastewater can be divided into the following categories: general cleaning water, ink wastewater, EDTA copper complex wastewater, copper ammonia complex wastewater, organic wastewater, fluorine-containing wastewater, high copper waste liquid, concentrated acid waste liquid, concentrated alkali waste liquid and other waste cylinder changing liquid. It contains copper, nickel, lead, tin and other heavy metal ions, high molecular organic matter, complexing agent, etc. its heavy metal ions, COD, SS, pH, etc. are all over the standard, with various types and complex pollution components.
15. Starch wastewater
Starch wastewater mainly comes from washing, pressure filtration, concentration and other process sections in the process of corn starch processing. The wastewater contains a lot of soluble organic pollutants, such as protein, sugar, carbohydrate, fat, amino acid, etc., followed by inorganic compounds containing N and P, and also contains a certain amount of volatile acid, ash, etc., which is a high concentration organic wastewater with good biochemical properties, The COD and SS of starch wastewater are 2500-6000 mg / L and 800-1200 mg / L respectively.
16. Slaughterhouse wastewater
Slaughterhouse wastewater contains a lot of blood, oil, hair, visceral debris, undigested food, feces and other pollutants, with uncomfortable blood red and bloody smell, and also contains Escherichia coli, fecal streptococcus and other pathogenic bacteria harmful to human health.
These wastewater have the characteristics of great change in concentration and high content of organic matter, which will seriously pollute the water body if directly discharged into the environment.
17. Coking wastewater
Coking wastewater is the washing water and gas washing water in the production process of coking plant and gas plant, the separated water after steam separation and tank drainage, which contains dozens of inorganic and organic compounds：
Inorganic compounds are mainly ammonia salt, sulfur, sulfide, etc；
In addition to phenols, organic compounds include monocyclic and polycyclic aromatic compounds, heterocyclic compounds containing nitrogen, sulfur and oxygen, etc.
Serious pollution is a prominent environmental problem in industrial wastewater discharge. It is a typical refractory organic wastewater with complex composition, high concentration, high chroma, high toxicity and stable properties.
Source: industrial wastewater circle
