CN111943447B

CN111943447B - Treatment process of printing and dyeing wastewater

Info

Publication number: CN111943447B
Application number: CN202010850216.2A
Authority: CN
Inventors: 王华钢; 俞立锋; 魏国庆
Original assignee: Zhuji Lanxin Environmental Protection Technology Co ltd
Current assignee: Zhuji Lanxin Environmental Protection Technology Co ltd
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2022-03-11
Anticipated expiration: 2040-08-21
Also published as: CN111943447A

Abstract

The application relates to a treatment process of printing and dyeing wastewater, which specifically comprises the following process steps: s1, collecting waste water, namely collecting the printing and dyeing waste water generated in different processes in the printing and dyeing process into a regulating tank uniformly to be mixed to obtain mixed waste water; s2, carrying out air flotation flocculation, namely conveying the mixed wastewater in the step S1 to an air flotation tank, adding an air flotation flocculating agent to obtain air flotation wastewater, and conveying the floating sludge to a sludge tank; s3, biochemical treatment, namely conveying the air floatation wastewater in the step S2 to a biochemical treatment tank for biochemical treatment to obtain biochemical treatment wastewater; s4, carrying out precipitation flocculation, namely conveying the biochemical treatment wastewater in the step S3 to a precipitation tank, adding a precipitation flocculant to obtain precipitation wastewater, and conveying the precipitated sludge to a sludge tank; s5, post-treatment, namely taking the precipitation wastewater in the step S4, and performing post-treatment to obtain post-treatment wastewater. This application has the advantage that can obtain better treatment to waste water treatment.

Description

Treatment process of printing and dyeing wastewater

Technical Field

The application relates to the field of wastewater treatment, in particular to a treatment process of printing and dyeing wastewater.

Background

The printing and dyeing wastewater is wastewater discharged from printing and dyeing factories which mainly process cotton, hemp, chemical fibers and blended products thereof. The amount of the printing and dyeing wastewater is large, 100-200 tons of water are consumed for each 1 ton of textiles processed by printing and dyeing, and 80-90% of the water becomes wastewater. The textile printing and dyeing wastewater has the characteristics of large water quantity, high organic pollutant content, large alkalinity, large water quality change and the like, belongs to one of industrial wastewater difficult to treat, and contains dye, slurry, auxiliary agent, oil agent, acid and alkali, fiber impurities, sand substances, inorganic salt and the like.

For example, the chinese patent application with application publication No. CN105399254A discloses a method for treating printing and dyeing wastewater, which specifically comprises the following steps: (1) filtering the printing and dyeing wastewater, adding hydrogen peroxide to control the concentration of the hydrogen peroxide in the wastewater to be between 0.001mol/L and 0.1mol/L, and introducing ozone and chlorine simultaneously; (2) pumping the treated wastewater into a regulating tank, and regulating the pH value to 8-9; (3) adding hydrogen peroxide again, and introducing ozone and chlorine simultaneously; (4) adding ferrous sulfate and alkali aluminum into the treated wastewater, and reacting for 4-5 hours; (5) adding hydrogen peroxide for the third time, and introducing ozone and chlorine simultaneously; (6) electrolyzing the printing and dyeing wastewater by using a high-frequency pulse generator, and adopting equal-gap pulses; (7) adding hydrogen peroxide for the fourth time, and introducing ozone and chlorine simultaneously; (8) and discharging into a clean water tank after settling and filtering.

With respect to the related art among the above, the inventors consider that the following drawbacks exist: although indexes such as chromaticity of the wastewater can be reduced by repeated oxidation and decoloration, pollutants needing to be treated in the wastewater are many, and a good treatment effect cannot be achieved by simply treating the wastewater in an oxidation mode.

Disclosure of Invention

In order to obtain better treatment effect to the waste water treatment, the application provides a treatment process of printing and dyeing waste water.

The application provides a treatment process of printing and dyeing wastewater, which adopts the following technical scheme:

a treatment process of printing and dyeing wastewater specifically comprises the following process steps:

s1, collecting wastewater, namely collecting the printing and dyeing wastewater generated in different working procedures in the printing and dyeing process to the outside uniformly

Mixing in a regulating tank to obtain mixed wastewater;

s2, carrying out air flotation flocculation, namely conveying the mixed wastewater in the step S1 to an air flotation tank, adding an air flotation flocculating agent to obtain air flotation wastewater, and conveying the floating sludge to a sludge tank;

s3, biochemical treatment, namely conveying the air floatation wastewater in the step S2 into a biochemical treatment tank to enter

Performing biochemical treatment to obtain biochemical treatment wastewater;

s4, carrying out precipitation flocculation, namely conveying the biochemical treatment wastewater in the step S3 to a precipitation tank, adding a precipitation flocculant to obtain precipitation wastewater, and conveying the precipitated sludge to a sludge tank;

s5, post-treatment, namely taking the precipitation wastewater in the step S4, and performing post-treatment to obtain post-treatment wastewater.

Through adopting above-mentioned technical scheme, carry out the air supporting after collecting the waste water of different processes of printing and dyeing in-process and mixing and handle, at this moment, highly dispersed small bubble is on adsorbing the pollutant of flocculating out in the waste water as the carrier to make its buoyancy be greater than self gravity and come-up resistance, consequently, the pollutant can flocculate and come-up to the sewage surface after the air supporting, can realize preliminary pollutant separation with the pollutant separation of come-up again. And COD, chromaticity and the like in the wastewater are treated by biochemical treatment, and the wastewater after precipitation, flocculation and post-treatment can reach the discharge standard and can even be recycled to a process with low requirement on water quality, so that the discharge amount of the sewage is greatly reduced, and the influence on the environment is also reduced.

Preferably, the air flotation flocculant used in step S2 includes the following components in parts by weight:

by adopting the technical scheme, the polyaluminum ferric chloride added into the wastewater can be hydrolyzed into polynuclear polymeric hydroxyl complex ions, and generates electrical neutralization, adsorption and sweeping actions with suspended colloid in the wastewater, and the PAM is cooperated with the polyaluminum ferric chloride through the adsorption bridging net-capturing action of chain molecules to improve the flocculation effect, thereby improving the effect of air flotation flocculation. And because the printing and dyeing sewage concentration in the air flotation flocculation step is high and the pH value is alkaline, compared with the use of cationic PAM and nonionic PAM, the flocculation effect of anionic PAM is better.

In addition, because magnesium sulfate is also added into the air-flotation flocculating agent, the magnesium sulfate can form MAP (struvite) with phosphorus and ammonia nitrogen in the wastewater, and can also decolor the water, thereby greatly reducing the treatment pressure during the subsequent treatment.

The oxygen generating agent added additionally can generate oxygen in the wastewater, and the oxygen is uniformly distributed in the wastewater and attached to the flocculated pollutants, so that the flocculated pollutants float upwards, solid-liquid separation is realized, and the flocculation floating effect of the polyaluminum ferric chloride and the cationic PAM can be promoted by adding the oxygen generating agent.

Preferably, the oxygen generating agent comprises the following components in percentage by weight:

50-60% of sodium percarbonate;

35-45% of water glass;

4-5% of a stabilizer;

and the baume degree of the water glass is 40-45.

By adopting the technical scheme, after the oxygen generating agent is added into the wastewater, the water glass is gradually dissolved, so that the sodium percarbonate is gradually released, the released sodium percarbonate is hydrolyzed, the hydrolyzed sodium percarbonate firstly releases hydrogen peroxide with bleaching capacity, and the hydrogen peroxide can oxidize and decolor colored substances in the wastewater and the flocculated pollutants, so that the chromaticity of the wastewater and the flocculated pollutants is reduced. The further decomposition of hydrogen peroxide releases oxygen which can be attached to the flocculated pollutants, so that the buoyancy of the flocculated pollutants is further improved, and the solid-liquid separation is easier.

The stabilizer is added into the oxygen generating agent to improve the stability of hydrogen peroxide in wastewater, reduce the possibility that hydrogen peroxide is decomposed in a short time and instantaneously release a large amount of oxygen, and the instantaneously released oxygen has a low utilization rate, only few pollutants can be attached to flocculation, and most of the pollutants float and dissipate, so that the speed of the oxygen generating agent for generating oxygen needs to be controlled. The addition of the stabilizer can ensure that the hydrogen peroxide can release oxygen more stably and continuously, thereby improving the utilization rate of the oxygen generating agent and improving the treatment effect of the air floatation flocculation step.

Although the magnesium sulfate added in the air flotation flocculating agent does not react with the hydrogen peroxide, the magnesium sulfate can react with the water glass and the metal ions in the wastewater, so that the catalytic action of the metal ions on the hydrogen peroxide is reduced, and the decomposition of the hydrogen peroxide is inhibited. When magnesium sulfate is used alone, precipitate is easily generated directly, and when magnesium sulfate is added together with water glass, magnesium silicate is easily generated, and magnesium silicate forms protective colloid to HO₂ ^-Protection is formed, so that the stability of the hydrogen peroxide is improved.

In addition, magnesium sulfate can generate magnesium hydroxide in wastewater and disperse in the wastewater in the form of positively charged micelles, and the positively charged micelles can adsorb HO generated by hydrogen peroxide decomposition₂ ^-Thereby preventing the further reaction of the hydrogen peroxide and the hydrogen peroxide to generate free radicals and playing a role in stabilizing the hydrogen peroxide.

Preferably, the stabilizer comprises the following components in percentage by weight:

40-50% of sodium acetate;

1wt% of sodium aminotriacetate 50-60%.

The sodium nitrilotriacetate can complex heavy metal to reduce the influence of the heavy metal on the oxygen release of the sodium percarbonate, so that the sodium percarbonate can release the oxygen for a long time. After the sodium acetate is dissolved in the water, the sodium acetate is hydrolyzed to absorb heat, so that the temperature of the wastewater near the oxygen generating agent is lower, and the stability of the hydrogen peroxide at low temperature is higher, so as to further improve the stability of the hydrogen peroxide. And the low water temperature of the wastewater means that more oxygen can be dissolved in the wastewater, the oxygen generated by the sodium percarbonate partially floats up directly, part is directly attached to flocculated pollutants, and part is dissolved in the wastewater. Wherein, the oxygen dissolved in the wastewater is released when the temperature of the wastewater rises, and the released oxygen is more easily attached to solid pollutants, so the addition of the sodium acetate can improve the stability and the utilization rate of the oxygen generating agent.

Preferably, the preparation process of the oxygen generating agent specifically comprises the following process steps:

a. mixing sodium percarbonate and sodium acetate according to a ratio to obtain a mixed material;

b. b, putting the mixed material in the step a into a fluidized bed, spraying water glass, and drying for 3 minutes at the spraying temperature of 70 ℃ to obtain a primary dried product;

c. and (3) spraying the sodium nitrilotriacetate solution on the primary dried product, and continuously drying for 5 minutes to obtain the oxygen generating agent.

By adopting the technical scheme, the sodium percarbonate and the sodium acetate are mixed, so that the release time of the sodium percarbonate and the release time of the sodium acetate are almost the same, the speed of the sodium acetate heat desorption is higher than that of the sodium percarbonate oxygen release, and the temperature of the ambient wastewater is reduced when the sodium percarbonate oxygen release, so that more oxygen can be dissolved. And after the sodium percarbonate and the sodium acetate are coated with the water glass, the sodium percarbonate which is easy to deliquesce is protected and is easier to store.

The temperature of the sprayed water glass and the sodium aminotriacetate is controlled because the stability of the sodium percarbonate is low, the sodium percarbonate is easy to thermally decompose when the spraying temperature is too high, and the sodium percarbonate is easy to decompose when the drying time is too long when the spraying temperature is too low. The reason why the drying time after spraying the water glass is limited is that the inventors found that when the spraying temperature is 70 ℃ and the drying time is 3 minutes, the spraying of the sodium nitrilotriacetate solution can make the sodium nitrilotriacetate solution well adhere to the water glass which has not been completely dried.

The Baume degree of the water glass is limited because the oxygen generating agent in the application adopts a special fluidized bed production process, when the Baume degree of the water glass is too high, a spray head is easy to block, and when the Baume degree of the water glass is too low, water in the water glass can cause the decomposition of sodium percarbonate, so the inventor finds that the water glass with the Baume degree of 40-45 needs to be selected.

Preferably, the step S3 specifically includes the following steps:

a. anaerobic treatment, namely conveying the air floatation wastewater in the step S2 to an anaerobic tank, adding an anaerobic microbial inoculum to obtain anaerobic wastewater, and conveying settled sludge to a water inlet of the anaerobic tank;

b. and (c) aerobic aeration, namely conveying the anaerobic wastewater in the step (b) to a deep well aeration tank, adding an aerobic microbial agent, and then carrying out aeration to obtain the biochemical treatment wastewater.

By adopting the technical scheme, the long-chain macromolecules which are difficult to degrade in the wastewater are hydrolyzed into short-chain micromolecular organic matters by the extracellular enzyme secreted by the anaerobic bacteria, but the removal rate of the anaerobic treatment is not very high and the short-chain micromolecular organic matters cannot be directly discharged, so the anaerobic wastewater obtained after the anaerobic treatment is further subjected to aerobic aeration, the organic matters are further degraded by the aerobic microbial inoculum, and the decomposition completeness of the organic matters is improved.

Preferably, the anaerobic microbial agent used in step S3 is selected from one or more of methanogenic bacteria, pseudomonas, lactobacillus, yeast and denitrifying bacteria.

By adopting the technical scheme, the air-flotation wastewater obtained after air-flotation flocculation contains oxygen with certain content, the oxygen content in the wastewater is too high, and the anaerobic treatment of the wastewater has certain negative effect, and facultative anaerobes such as denitrifying bacilli exist in the anaerobic microbial inoculum, so that the residual oxygen in the wastewater can be consumed rapidly.

In addition, the biodegradability of the printing and dyeing sewage is low due to the characteristics of the printing and dyeing sewage, and after sodium acetate added into the oxygen generating agent is dissolved in the wastewater, the stability of the oxygen generating agent can be improved, and the oxygen generating agent can also be used as a carbon source of various strains, for example, sodium acetate can be excessively adsorbed by denitrifying bacteria, so that the COD value of the wastewater after biochemical treatment can be maintained at a low level when the denitrification is carried out by taking the sodium acetate as the carbon source.

Preferably, the aerobic microbial agent used in step S3 is selected from one or more of bacillus, yeast, micrococcus, nitrosomonas, nitrobacter, pseudomonas and acinetobacter.

By adopting the technical scheme, the aerobic microbial inoculum can improve the treatment effect on the wastewater by selecting different strains.

Preferably, the precipitation flocculant used in step S4 comprises the following components in percentage by weight:

11wt% of polyferric sulfate 15-20%;

0.3wt% cationic PAM 80-85%.

Through adopting above-mentioned technical scheme, often contain the impurity of more negative electricity in the waste water after biochemical treatment, the flocculation and precipitation of these impurities then is more suitable for adopting cation PAM. And through the treatment of the above-mentioned multichannel processes, the turbidity of sewage at this moment is not high, use cation PAM and polyferric sulfate to cooperate not only flocculation effectual, and the sedimentation rate is fast, deposit the mud that obtains closely knit, very do benefit to a small amount of impurity that exists in the quick sediment waste water.

Preferably, the step S5 specifically includes the following steps:

a. performing oxidation treatment, namely introducing ozone into the precipitated wastewater obtained in the step S4 for oxidation treatment to obtain oxidized wastewater;

b. b, filtering the wastewater, namely conveying the oxidized wastewater obtained in the step a into a sand filter, and filtering to obtain filtered wastewater;

c. and (c) recycling and storing, namely conveying the filtered wastewater obtained in the step (b) into a recycling pool to obtain post-treatment wastewater, wherein the post-treatment wastewater can be recycled or directly discharged to a municipal sewage pipeline.

By adopting the technical scheme, the wastewater after the biochemical treatment is further subjected to ozone oxidation and filtration, the COD, the chromaticity, solid impurities and the like of the wastewater can be further reduced, and the quality of the wastewater finally conveyed into the recycling tank is better.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the COD, the chroma, the ammonia nitrogen and the like in the wastewater are reduced by carrying out air floatation flocculation, biochemical treatment, precipitation flocculation and post-treatment on the collected wastewater, so that the discharge amount of the sewage is greatly reduced, and the influence on the environment is reduced;

2. the wastewater is treated by using the air-floating flocculating agent with special composition and proportion, so that the treatment effect of the air-floating flocculating treatment step can be greatly improved;

3. by adding the oxygen generating agent with special composition and proportion into the air-floating flocculating agent, the chromaticity and the like in the wastewater can be further removed, the treatment effect of the air-floating flocculating treatment step can be further improved, and the magnesium sulfate in the air-floating flocculating agent can not only treat the wastewater, but also improve the stability of the oxygen generating agent;

4. by adopting the stabilizing agent with special composition and proportion, the treatment effect of the air floatation flocculation treatment step can be further improved, and the treatment effect of the subsequent biochemical treatment step can also be improved;

5. by adopting the special preparation process of the oxygen generating agent, the decomposition of sodium percarbonate and the possibility of nozzle blockage of a fluidized bed in the process of producing the oxygen generating agent can be reduced.

Drawings

FIG. 1 is a flow chart of a wastewater treatment process of example 1 of the present application.

Detailed Description

Example 1

The present application is described in further detail below with reference to the attached drawings.

Referring to fig. 1, the application discloses a treatment process of printing and dyeing wastewater, which specifically comprises the following process steps:

and S1, collecting waste water, namely uniformly collecting the printing and dyeing waste water generated in different processes in the printing and dyeing process into a regulating tank for mixing to obtain mixed waste water.

And S2, carrying out air flotation flocculation, namely conveying the mixed wastewater in the step S1 to an air flotation tank, adding an air flotation flocculating agent to obtain air flotation wastewater, and conveying the floating sludge to a sludge tank.

The air flotation flocculant used in the step S2 comprises the following components in parts by weight:

the oxygen generating agent in the air flotation flocculating agent comprises the following components in percentage by weight:

50% of sodium percarbonate;

45% of water glass;

5% of a stabilizer;

and the baume degree of the water glass is 40.

The stabilizing agent in the oxygen generating agent comprises the following components in percentage by weight:

50% of sodium acetate;

1% by weight sodium aminotriacetate 50%.

The preparation process of the oxygen generating agent specifically comprises the following process steps:

S3, biochemical treatment, namely conveying the air floatation wastewater in the step S2 to a biochemical treatment tank for biochemical treatment, and specifically comprising the following process steps:

b. and (c) aerobic aeration, namely conveying the anaerobic wastewater in the step (b) into a deep well aeration tank, adding an aerobic microbial agent, and then carrying out aeration to obtain the biochemical treatment wastewater.

Wherein the anaerobic bacteria agent is a mixture of methanogenic bacteria, pseudomonas, lactobacillus, denitrifying bacillus and the like in weight ratio.

Wherein the aerobic microbial agent is a mixture of bacillus, saccharomycetes, micrococcus, nitrobacillus, pseudomonas, acinetobacter and the like in a weight ratio.

S4, carrying out precipitation flocculation, namely conveying the biochemical treatment wastewater in the step S3 to a precipitation tank, adding a precipitation flocculant to obtain precipitation wastewater, and conveying the precipitated sludge to a sludge tank.

The precipitation flocculant used in step S4 comprises the following components in percentage by weight:

11wt% of polyferric sulfate 20%;

0.3wt% cationic PAM 80%.

S5, post-treatment, namely, post-treatment is carried out on the precipitation wastewater in the step S4, and the method specifically comprises the following process steps:

Examples 2-6 differ from example 1 in that,

comparative example

The difference between the comparative example 1 and the example 1 is that the step S2 air flotation flocculation is not carried out in the wastewater treatment process, namely, the mixed wastewater in the regulating tank is directly subjected to biochemical treatment.

The difference between the comparative example 2 and the example 1 is that no oxygen generating agent is added to the air flotation flocculant.

Comparative example 3 differs from example 1 in that no magnesium sulfate was added to the air flotation flocculant.

Comparative example 4 differs from example 1 in that no stabilizer is added to the oxygen generating agent and the weight ratio of sodium percarbonate to water glass is 1: 1.

comparative example 5 differs from example 1 in that the stabilizer used only 1% by weight of sodium aminotriacetate and no sodium acetate was added.

Detection method

The COD of the sewage is detected according to the regulation in the specification HJ-T399-2007 determination of chemical oxygen demand of water quality and rapid digestion spectrophotometry.

The measurement of the color of the wastewater was carried out according to the regulation of the Specification GB 11903-1989-measurement of color of water quality ".

The detection method of the ammonia nitrogen in the sewage is carried out according to the regulation in the specification HJ 535-2009 reagent spectrophotometry for measuring ammonia nitrogen in water.

The detection of the total nitrogen of the sewage is carried out according to the regulation in the specification HJ 636-2012 determination of total nitrogen of water quality alkaline potassium persulfate digestion ultraviolet spectrophotometry.

The test results are shown in the following table:

conclusion

It can be seen from the data of comparative example 1 and comparative example 1 that the wastewater was not subjected to the air flotation flocculation treatment in comparative example 1, but was subjected to the biochemical treatment directly. At this time, the wastewater has high concentrations of insoluble impurities, and the high concentrations of the impurities will affect the biochemical treatment effect to a great extent if not removed, and finally, the data of the wastewater after the treatment in the comparative example 1 is significantly worse than the data of the wastewater after the treatment in the example 1.

It can be seen from the data of comparative example 1, comparative example 1 and comparative example 2 that since the oxygen generating agent is not added to the air-float flocculant of comparative example 2, many insoluble impurities are not easily floated even though they are flocculated, and thus it is not easy to completely remove the insoluble impurities in the wastewater. The impurities which are not removed influence the effect of the subsequent biochemical treatment, and certainly, compared with the method without the air floatation flocculation treatment in the comparative example 1, the method has the advantage that various data of the wastewater after the treatment in the comparative example 2 are obviously better. This means that the effect of wastewater treatment can be greatly improved by performing air flotation flocculation, and the effect of air flotation flocculation can be further improved by additionally adding an oxygen generating agent into the air flotation flocculant.

The data of the comparative example 1 and the comparative example 3 show that, because magnesium sulfate is not added in the comparative example 3, the magnesium sulfate can remove ammonia nitrogen in water and can decolorize water, the ammonia nitrogen in the wastewater treated in the comparative example 3 is increased, and particularly the chroma is increased to a great extent.

It can be seen from the data of comparative examples 1 and 4 that, since no stabilizer is added in comparative example 4, once the oxygen generating agent without the stabilizer is decomposed to generate hydrogen peroxide, oxygen is generated at a higher speed, a large amount of rapidly generated oxygen escapes, and the floating promotion effect on flocculated impurities is weakened, each item of data of the wastewater after the treatment in comparative example 4 is obviously worse.

It can be seen from the data of comparative example 1 and comparative example 5 that, since sodium acetate is not added in comparative example 5, the temperature of the wastewater around the sodium acetate can be reduced due to the heat of sodium acetate desorption, so that the oxygen content around the sodium acetate is increased, and the sodium acetate as a carbon source can promote the effect of subsequent biochemical treatment. And in the comparative example 5, sodium acetate is not added, so that the floating promoting effect of the air-floating flocculating agent on the flocculated and agglomerated impurities is weakened, and the effect of subsequent biochemical treatment is weakened. Finally, the data of the wastewater treated in the comparative example 5 are obviously worse.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. A treatment process of printing and dyeing wastewater is characterized by comprising the following steps: the method specifically comprises the following process steps:

s1, collecting waste water, namely collecting the printing and dyeing waste water generated in different processes in the printing and dyeing process into a regulating tank uniformly to be mixed to obtain mixed waste water;

s3, performing biochemical treatment, namely conveying the air floatation wastewater in the step S2 to a biochemical treatment tank for biochemical treatment to obtain biochemical treatment wastewater;

s5, post-treatment, namely taking the precipitation wastewater in the step S4, and performing post-treatment to obtain post-treatment wastewater;

0.2-0.3 part of polyaluminum ferric chloride;

1-2 parts of anionic PAM;

140 portions of magnesium sulfate and 180 portions of;

5-10 parts of an oxygen generating agent;

800 portions of water and 1000 portions of water;

the oxygen generating agent comprises the following components in percentage by weight:

50-60% of sodium percarbonate;

35-45% of water glass;

4-5% of a stabilizer;

the Baume degree of the water glass is 40-45;

the stabilizer comprises the following components in percentage by weight:

40-50% of sodium acetate;

1wt% of sodium aminotriacetate 50-60%;

2. The process for treating printing and dyeing wastewater according to claim 1, characterized in that: the step S3 specifically includes the following process steps:

b. and (b) aerobic aeration, namely conveying the anaerobic wastewater in the step (a) to a deep well aeration tank, adding an aerobic microbial agent, and then carrying out aeration to obtain the biochemical treatment wastewater.

3. The process for treating printing and dyeing wastewater according to claim 2, characterized in that: the anaerobic microbial agent used in the step S3 is one or more selected from methanogenic bacteria, pseudomonas, lactic acid bacteria, yeast and denitrifying bacteria.

4. The process for treating printing and dyeing wastewater according to claim 2, characterized in that: the aerobic microbial agent used in the step S3 is selected from one or more of bacillus, yeast, micrococcus, nitrosomonas, nitrobacillus, pseudomonas and acinetobacter.

5. The process for treating printing and dyeing wastewater according to claim 1, characterized in that: the precipitation flocculant used in the step S4 comprises the following components in percentage by weight:

11wt% of polyferric sulfate 15-20%;

0.3wt% cationic PAM 80-85%.

6. The process for treating printing and dyeing wastewater according to claim 1, characterized in that: the step S5 specifically includes the following process steps: