CN113716749A

CN113716749A - Method for removing COD (chemical oxygen demand) in high-salinity wastewater

Info

Publication number: CN113716749A
Application number: CN202111057087.2A
Authority: CN
Inventors: 胡建康
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2021-11-30

Abstract

The invention relates to a method for removing COD (chemical oxygen demand) in high-salinity wastewater, which comprises the steps of primary treatment, membrane filtration and removal of solid pollutants in a suspended state in sewage; secondary treatment, namely performing primary resin adsorption to remove organic matters which are in a colloid state and a dissolved state and are partially difficult to degrade in the sewage; and third-stage treatment, namely, second resin adsorption, and further treatment of refractory organic matters and soluble inorganic matters causing water eutrophication. The original wastewater is subjected to suction filtration by a mixed membrane, the COD concentration in the wastewater is reduced to less than 2000PPM, the wastewater is lifted and pressurized by a water pump, the COD concentration in the wastewater can be reduced to less than 100PPM by adsorption of a macroporous resin 1, the wastewater is lifted and pressurized by the water pump, and the COD concentration in the wastewater can be reduced to less than 50PPM by adsorption of a macroporous resin 2, so that the standard discharge is realized; the invention has high COD removing efficiency, low primary investment cost, low running cost, convenient equipment operation and maintenance and no secondary pollution.

Description

Method for removing COD (chemical oxygen demand) in high-salinity wastewater

Technical Field

The invention relates to the technical field of environmental engineering, in particular to a method for removing COD (chemical oxygen demand) in high-salinity wastewater.

Background

Chemical Oxygen Demand (abbreviated as COD) is the amount of reducing substances to be oxidized in a water sample measured chemically. Chemical oxygen demand is an important and relatively fast measurable parameter of organic pollution in the study of river pollution and properties of industrial wastewater and the operational management of wastewater treatment plants. High chemical oxygen demand means that the water contains a large amount of reducing substances, mainly organic pollutants. The higher the chemical oxygen demand, the more serious the organic pollution of river water, and the sources of the organic pollution may be pesticides, chemical plants, organic fertilizers and the like. If not treated, a plurality of organic pollutants can be adsorbed by the bottom mud at the bottom of the river to be deposited, and the organic pollutants can cause lasting toxic action on aquatic organisms within a plurality of years in the future. After massive death of aquatic life, the ecosystem in the river is destroyed. If people eat organisms in water, a large amount of toxins in the organisms are absorbed and accumulated in the bodies, and the toxins have carcinogenic, teratogenic and mutagenic effects and are extremely dangerous to people. In addition, irrigation with contaminated river water also affects plants and crops, which are prone to poor growth, and people cannot eat them. However, the high chemical oxygen demand does not necessarily mean the above-mentioned damage, and it is judged how the influence on the water quality and ecology is caused by detailed analysis such as analysis of the kind of organic matter. Whether it is harmful to human body, etc. If the detailed analysis cannot be carried out, the chemical oxygen demand measurement can be carried out on the water sample at intervals of several days, and if the value is reduced greatly before comparison, the reduced substances contained in the water are mainly organic matters which are easy to degrade, and the harm to human bodies and organisms is relatively light.

Therefore, in wastewater treatment works related to wastewater treatment plants, wastewater pipe networks, sludge treatment, and reuse of reclaimed water, water containing a large amount of organic substances contaminates the ion exchange resin, particularly the anion exchange resin, when passing through the desalination system, and the resin exchange capacity is lowered. The organic matter can be reduced by about 50% during pretreatment (coagulation, clarification and filtration), but cannot be removed in a desalting system, so that the organic matter is usually brought into a boiler through make-up water to reduce the pH value of boiler water. Sometimes organic matter may also be carried into the steam system and condensate, lowering the pH and causing corrosion of the system. The high content of organic matter in the circulating water system promotes the propagation of microorganisms. For desalination, furnace water or circulating water systems, the lower the COD, the better, but there is no uniform restriction index. When COD (KMnO4 method) >5mg/L in the circulating cooling water system, the water quality began to deteriorate.

Therefore, the method for effectively treating COD is an important link in the wastewater treatment.

The invention of the publication No. CN112777718A is a patent application of the treatment method of high-salinity wastewater, and the disclosed technical scheme comprises the following steps: optionally pretreating the high-salinity wastewater to ensure that the COD of the high-salinity wastewater is 60-20000 mg/l in advance; adding hypochlorite into the pretreated wastewater, wherein the molar ratio of the hypochlorite to the COD in each ton of wastewater is 0.05-1000, and uniformly mixing and continuously reacting; after the reaction is finished, a quenching agent is optionally added to obtain external drainage with COD of less than 30 mg/l. The high-salinity wastewater treatment method has low energy consumption and simple and convenient operation, can avoid the stop of the device mainly aiming at the emergency treatment of the external drainage under the condition of abnormal fluctuation of the wastewater treatment device, does not damage the original wastewater treatment system, and simultaneously solves the problem of environment pollution caused by the discharge of the overproof wastewater; the method uses a hypochlorite oxidation method, mainly used as an emergency treatment method, and is used for dealing with abnormal fluctuation conditions of a wastewater treatment device.

The invention discloses an authorized publication number CN105016541B, which is named as a method for separating and recovering salt in high-salinity wastewater, and the method disclosed by the invention comprises the following steps: the method comprises the steps of separating and recovering salt in the high-salinity wastewater and producing ion exchange regenerated liquid through strengthening pretreatment, ion exchange, membrane concentration I, salt separation I, evaporative crystallization I and membrane concentration II; separating and recycling salt from the ion exchange regeneration waste liquid through a second salt separation step and a second evaporation crystallization step; the unused regeneration liquid is evaporated and crystallized to realize the separation and the recycling of salt and water; carrying out electrolytic oxidation on the high-concentration COD generated in the first evaporation crystallization step; carrying out electrolytic oxidation on the high-concentration COD generated by the second evaporation crystallization; carrying out electrolytic oxidation on the high-concentration COD generated by the evaporation and crystallization III; chlorine generated by the electrolytic oxidation is absorbed by chlorine to generate the disinfectant. The invention realizes zero discharge treatment of the high-salt wastewater, recovers clear water and salts in the wastewater according to quality, produces ion exchange regenerated liquid and bactericide in the process, and reduces the medicament consumption and secondary pollution of system operation; the scheme carries out three times of crystallization and three times of electrolytic oxidation treatment, and carries out complete treatment on the wastewater.

The utility model discloses a utility model patent of a waste water treatment system for removing COD in high salt waste water with the name of publication No. CN211712862U, the disclosed waste water treatment system specifically comprises a regulating reservoir, a pH value regulating reservoir, a first solid-liquid separation device, an evaporation plant, a second solid-liquid separation device, a mixing pool and a COD removing device which are sequentially communicated, wherein the evaporation plant and the second solid-liquid separation device are respectively communicated with the mixing pool, and the mixing pool is communicated with the COD removing device; the wastewater treatment system provides a treatment system and also describes a wastewater treatment mode.

The high-salinity wastewater is wastewater with the total salt mass fraction of at least 1 percent, and the wastewater contains various substances including salt, oil, organic heavy metals, radioactive substances and the like. At present, how to effectively treat COD in high-salinity wastewater generated in industrial production is a great industrial problem, most enterprises in China treat the COD of the high-salinity wastewater, and the common methods mainly comprise a physical method, a chemical precipitation method, an air floatation method, an activated carbon adsorption method, a biological method, a membrane separation method, an electrolytic method, an ion exchange method, an oxidation method and the like, but the methods have low treatment efficiency, high operation difficulty or high treatment cost, so the solution effect is not ideal.

The physical grid method can remove impurities in water, the impurities are COD, a lot of COD can be directly removed by filtering the impurities, but the treatment efficiency is low, and the treated wastewater can not reach the discharge standard and can be used as primary treatment.

The chemical precipitation method is a method for removing COD by adding a flocculating agent into wastewater, utilizing the adsorption bridging, double electric layer compression and net catching effects of the flocculating agent to destabilize, mutually collide and coagulate colloids and suspended matters in the water to form flocculating constituents, and separating particles from the water by using a precipitation or air flotation process, but the treatment efficiency is low, and the treated wastewater can not reach the discharge standard and can be used as primary treatment.

The air flotation process is a process of separating solids, precipitates, colloids, and the like in a solution from a mother liquor by air bubble adsorption separation, which is referred to as air flotation separation. The technology utilizes the difference of surface activity of various original dissolved and suspended substances in water. Or a method of separation by difference in surface activity caused by the addition of a drug. The treatment efficiency is low, and the treated wastewater can not reach the discharge standard.

The active carbon adsorption method can adsorb inorganic impurities, granular organic matters and metal substances in the wastewater, can be used as pretreatment, and can reduce the COD which is easier to treat.

The biological method treatment is one of the most common methods for treating the waste water at present, and has the characteristics of wide application range, strong adaptability, economy, high efficiency, harmlessness and the like. In general, the most common method is the traditional activated sludge process. The traditional activated sludge method is an aerobic biological treatment method of wastewater, and is the most widely used method for treating urban wastewater at present. It can remove soluble and colloidal biochemical organic substances, suspended solids and other substances adsorbed by activated sludge from wastewater, and can also remove a part of phosphorus and nitrogen. The activated sludge method has high removal rate and is suitable for treating wastewater with high water quality requirement and relatively stable water quality. But is not good at adapting to the change of water quality, and oxygen supply can not be fully utilized; the air supply is evenly distributed along the pond water, so that the oxygen content at the front section is insufficient, and the oxygen content at the rear section is excessive; the aeration structure is huge and the occupied area is large.

The membrane separation technology is a novel separation technology for separating, purifying and concentrating target substances by utilizing the difference of selective permeability of membranes to each component in a mixture. Currently, common membrane technologies include ultrafiltration, microfiltration, electrodialysis, and reverse osmosis. Wherein, when the ultrafiltration and the microfiltration are used for treating the industrial wastewater, the salt in the wastewater can not be effectively removed, but Suspended Solids (SS) and colloid COD can be effectively intercepted; electrodialysis (electrodialysis) and Reverse Osmosis (RO) techniques are the most efficient and commonly used desalination techniques. The main difficulties limiting the application and popularization of membrane technical engineering are high cost of the membrane, short service life, easy pollution, scaling and blockage, and the like. With the development of membrane production technology, membrane technology will be used more and more in the field of wastewater treatment.

The electrolysis process has the characteristic that the wastewater has higher conductivity under the condition of high salinity, and provides a good development space for the electrochemical method in the aspect of high-salinity organic wastewater treatment. The high-salt wastewater is subjected to a series of oxidation-reduction reactions in an electrolytic cell to generate water-insoluble substances, and the water-insoluble substances are removed through precipitation (or air flotation) or direct oxidation-reduction into harmless gases, so that COD is reduced. When the sodium chloride in the solution is electrolyzed, part of chlorine gas generated on the anode is dissolved in the solution to generate a secondary reaction to generate hypochlorite and chlorate, and the hypochlorite and the chlorate play a role in bleaching the solution. It is the above-mentioned combined synergistic effect that degrades the organic pollutants in the solution. Because of the limitations of electrochemical theory, high energy consumption, power shortage and other problems, the current process for electrolyzing high-salinity wastewater is still in the research stage.

Ion exchange is a unit operation process in which exchange reactions between ions in solution and counter ions on insoluble polymers (containing fixed anions or cations) are typically involved. When the ion exchange method is adopted, the wastewater firstly passes through a cation exchange column, wherein ions (Na + and the like) with positive charges are replaced by H + and are retained in the exchange column; thereafter, the negatively charged ions (CI-, etc.) are replaced by OH-in the anion exchange column for desalting purposes. However, a major problem with this process is that the solids suspension in the wastewater can clog the resin and lose its effectiveness, and that regeneration of the ion exchange resin requires high costs and the exchanged waste is difficult to dispose of.

The oxidation method removes COD in water, and can oxidize reductive organic substances by ozone or oxidative substances such as hypochlorous acid, thereby achieving good removal effect. Ozone is a strong oxidant, has high reaction speed with reduced pollutants, is convenient to use, does not produce secondary pollution, and can be used for disinfection, color removal, deodorization, organic matter removal, COD reduction and the like of wastewater. The single use of the ozone oxidation method has high cost and high treatment cost, and the oxidation reaction has selectivity and has poor oxidation effect on certain halogenated hydrocarbons, pesticides and the like.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for removing COD in high-salinity wastewater. The technical defects of low treatment efficiency, high operation difficulty and high treatment cost in the prior art are overcome.

The invention relates to a method for removing COD (chemical oxygen demand) in high-salinity wastewater, which is realized by the following technical scheme.

The invention adopts macroporous resin for adsorption, the principle of the adsorption process is that the macroporous resin adsorption material is utilized to selectively adsorb components or substances to be removed, when the adsorption is saturated, a specific desorption agent is utilized to desorb the adsorption material, so that the adsorption material is regenerated, and the process is continuously and circularly carried out.

The technical scheme for treating the COD in the high-salinity wastewater is divided into primary treatment, secondary treatment and tertiary treatment according to the treatment degree.

First-stage treatment, membrane filtration, mainly removing solid pollutants in a suspended state in the wastewater. The wastewater after the primary treatment is used as the pretreatment wastewater of the secondary treatment; the membrane filtration can be general membrane filtration or mixed membrane filtration, and a suction filtration mode is adopted;

secondary treatment, namely primary resin adsorption, mainly removing colloid and dissolved organic matters and part of nondegradable organic matters in the wastewater, wherein the removal rate can reach over 90 percent;

and third-stage treatment, namely, resin adsorption for the second time, and further treatment of organic matters and soluble inorganic matters such as phosphorus which are difficult to degrade and can cause eutrophication of the water body.

Optionally, in the technical scheme, a four-stage treatment scheme can also be adopted, namely, a third-time resin adsorption is added on the basis of the three-stage treatment; and performing third resin adsorption treatment on the wastewater subjected to the third-stage treatment, so that the treatment effect is improved, and the treated wastewater with a higher standard is obtained.

The technical scheme of the invention is suitable for the treatment of high-salinity wastewater extracted by the acidic phosphorus extractant; generally, such wastewater is highly acidic, and the acidic phosphorus extractant actually tested in the present invention is extracted from high-salt wastewater with a pH of 2, i.e., wastewater with acidity up to pH 2 can be treated.

Further, the primary membrane filtration treatment aims at removing solid pollutants in a suspended state in the wastewater, and technical schemes which can achieve the aims in the prior art can be used for the technical scheme of the invention;

in the secondary treatment and the tertiary treatment, in the technical scheme of the invention, aromatic macroporous adsorption resin is preferably selected; more particularly, SD-300 resin can be preferably used, wherein SD300 is aromatic macroporous absorption resin with a styrene framework, and can separate and absorb non-polar substances in polar solution.

Furthermore, in the technical scheme of the invention, the pore diameter of the membrane is 0.1-0.5 micron; preferably the membrane has a pore size of 0.12 to 0.3 microns; more preferably the pore size of the membrane is 0.15 micron; the membrane is used for removing suspended solid pollutants in the wastewater;

further, the method of the present invention further comprises a resin desorption treatment, specifically comprising:

treating the resin after the resin is adsorbed and saturated by using a desorption agent, wherein the desorption agent comprises desorption agents such as acid, alkali, water and the like; specifically, the resin is firstly washed by 5% sodium hydroxide solution, the residual alkalinity of the washed waste alkali liquor is about 0.5mol/L, the washed waste alkali liquor is mixed with the ortho-acidic wastewater in a ratio of about 1:1, the mixture is filtered, the filtered wastewater enters the original wastewater for treatment, filter residues are transferred to a neutralization residue storage, the resin is washed by pure water for 8 times, and the washed wastewater enters the original wastewater for treatment. Washing the resin after alkaline washing with hydrochloric acid of about 1N, treating the washed waste acid liquid in the original wastewater, washing the resin with pure water for 6 times, and treating the washed wastewater in the original wastewater. The resin after being cleaned can be recycled. The pure water may be demineralized, distilled or deionized water.

Further, in the technical scheme of the invention, after the resin is saturated by adsorption, all the washing wastewater or waste liquid generated in the desorption treatment can be added into the original wastewater and is subjected to cyclic treatment together, so that all the wastewater and waste acid alkali liquor generated in the desorption treatment of the macroporous adsorption resin can be added into the original wastewater for treatment; the process does not produce waste water and waste acid alkali liquor additionally.

Has the advantages that: the whole process is that the original wastewater is subjected to suction filtration by a mixed membrane, the COD concentration in the wastewater is reduced to less than 2000PPM, then the wastewater is lifted and pressurized by a water pump, the COD concentration in the wastewater can be reduced to less than 100PPM through adsorption by macroporous resin, then the wastewater is lifted and pressurized by the water pump, and the COD concentration in the wastewater can be reduced to less than 50PPM through adsorption by the macroporous resin, so that the standard discharge is realized; the invention has the advantages of high COD removal efficiency, low primary investment cost, low operation cost, convenient equipment operation and maintenance, advanced and reliable process and no secondary pollution.

In order to make the purpose and technical solution of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the implementation examples of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be made by a person skilled in the art without inventive effort based on the described embodiments of the invention, fall within the scope of protection of the invention.

Drawings

FIG. 1 is a schematic flow chart of the method of the present invention

Wherein, the macroporous resin 1 and the macroporous resin 2 respectively represent a first resin used for adsorption and a second resin used for adsorption, and the resins used for adsorption generally select the resins with the same specification; resins of various specifications may also be employed for specific properties of wastewater.

Detailed description of the preferred embodiments

The technical solution of the present invention is further illustrated by the following specific examples. In the following embodiments, the raw materials are all commercial products purchased from the relevant manufacturing enterprises or commercial departments, unless otherwise specified.

FIG. 1 shows a schematic flow chart of COD treatment in high-salinity wastewater in the method according to the technical scheme of the invention. As can be seen from the flow chart of FIG. 1, the wastewater is the raffinate wastewater of the acidic phosphorus extractant, and the pH value of the wastewater is 2 after the wastewater is treated by the primary treatment membrane device; then, performing secondary treatment by an exchange device loaded with macroporous resin 1, wherein the pH value of the wastewater is 2, and the COD content of the wastewater subjected to membrane treatment is less than 2000mg/L, and the COD content of the wastewater is less than 100 mg/L; then, carrying out three-stage treatment, namely, carrying out second resin adsorption treatment of the macroporous resin 2 to generate standard wastewater with COD content less than 50 mg/L; after the macroporous resin 1 subjected to secondary treatment and the macroporous resin 2 subjected to tertiary treatment reach adsorption saturation, performing alkali solution treatment, first water treatment, acid treatment and second water treatment, and recycling the obtained macroporous resin after the treatments; wherein, the macroporous resin 1 and the macroporous resin 2 can be mixed and then treated together; mixing the waste alkali liquor and the treated wastewater subjected to the alkali solution treatment and the primary water treatment, mixing the waste alkali liquor and the treated wastewater with the acidic phosphorus extractant raffinate wastewater according to the volume ratio of 1:1, filtering to remove waste residues in the waste alkali liquor, mixing the obtained wastewater with the acidic phosphorus extractant raffinate wastewater to be treated, and performing circular treatment; and (3) carrying out acid treatment and secondary water treatment on the macroporous resin 1 and the macroporous resin 2 subjected to the alkali solution treatment and the primary water treatment, recycling the obtained treated macroporous resin, combining the obtained waste acid liquid and the waste water with the extraction residual wastewater of the acidic phosphorus extractant, and carrying out recycling treatment.

As can be seen from the figure 1, in the technical scheme of the invention, the waste alkali solution, the waste acid solution and the treated wastewater which are used for desorbing the macroporous resin with saturated adsorption can be combined with the original extraction waste water of the acidic phosphorus extractant to be treated for circular treatment, and no resin desorption waste liquid is generated additionally.

In the following examples, the experimental conditions are as follows:

the pore size of the membrane is 0.15 micron;

the macroporous resin 1 and the macroporous resin 2 are selected from SD-300 resin, and the classification form of the macroporous resin is aromatic; the skeleton is styrene; the water content percent is 50-60; the specific surface area is 900-1200m 2/g; the pore volume is more than or equal to 0.8 ml/g.

The macroporous resin is loaded in a transparent PVC pipe with the outer diameter of 50mm, and the loading capacity of the macroporous resin SD-300 is 500 ml;

the wastewater sample to be treated is the raffinate wastewater of an acidic phosphorus extractant;

wherein the alkali is sodium hydroxide (5% by weight); the acid is hydrochloric acid (1N);

the wastewater sample is treated according to the flow shown in figure 1, and the flow rate is as follows: 2.0L/h; when the effluent index COD of the exchange column loaded with the macroporous resin 1 is more than 100mg/l, the exchange column is considered to reach a saturated state, and desorption treatment is carried out by using a desorption agent; when the effluent index COD of the exchange column loaded with the macroporous resin 2 is more than 50mg/l, the exchange column is considered to reach a saturated state, and desorption treatment is carried out by using a desorption agent.

Wherein:

SD-300 macroporous resin is purchased from Shanxi nuclear acute controversy chemical industry Co., Ltd;

the mixed membranes used for the tests were produced by the new inferior purification plant of Shanghai.

Examples 1 to 2

	COD of inlet water	Water inflow	COD of effluent
				Example 1	192mg/L	50L	27.9mg/L
Example 2	192mg/L	300L	53mg/L

SD-300 resin desorption in examples 1-2

Desorbing by using macroporous resin 1:

1. the resin was poured into a beaker and 500ml of 1.2N liquid alkali, stirred for 5 minutes and soaked for 20 hours. Washing the waste alkali liquor with 10750mg/l COD for 8 times (500 ml each time);

2. acid washing, adding 500ml of 1.15N hydrochloric acid aqueous solution, stirring for 5 minutes, soaking for 4 hours until COD in the waste acid solution is less than 50mg/l, washing with 500ml of water for 6 times until the COD is less than 50 mg/l;

3. 4500ml of waste alkali and 3500ml of waste acid are produced in the desorption step.

Wherein the alkali is sodium hydroxide; the acid is hydrochloric acid;

and (3) desorbing by using macroporous resin 2:

1. the resin is poured into a beaker and 500ml of 5 percent liquid alkali, stirred for 5 minutes, and after being soaked for 30 minutes, 0.5N, COD5800mg/l of alkali is left. The water washing is carried out for 8 times, each time is 500ml, the 1 st COD is 3010mg/l, the 2 nd COD is 2109mg/l, the 3 rd COD is 1241mg/l, the 4 th COD is 983mg/l, the 5 th COD is 827mg/l, the 6 th COD is 613mg/l, the 7 th COD is 445mg/l and the 8 th COD is 328 mg/l.

2. Acid washing (1.15N), stirring 500ml for 5 minutes, soaking for 3 hours, washing the waste acid liquor with COD less than 50mg/l 6 times by 500ml, COD less than 50 mg/l.

3. 4500ml of waste alkali and 3500ml of waste acid are produced together.

Examples 3 to 5

	COD of inlet water	Water inflow	COD of effluent
				Example 3	190mg/L	50L	35.8mg/L
Example 4	190mg/L	150L	43.2mg/L
				Example 5	190mg/L	300L	51.8mg/L

SD-300 resin desorption in examples 3-5

Desorbing by using macroporous resin 1:

1. the resin is poured into a beaker and 500ml of 5 percent liquid alkali, stirred for 5 minutes, and after the resin is soaked for 18 hours, 0.58N, COD9800mg/l of alkali is remained. Washing with 500ml water for 8 times; 5880mg/l of COD for 1 st time, 4180mg/l of COD for 2 nd time, 2271mg/l of COD for 3 rd time, 1821mg/l of COD for 4 th time, 1380mg/l of COD for 5 th time, 1105mg/l of COD for 6 th time, 826mg/l of COD for 7 th time and 719mg/l of COD for 8 th time.

2. Acid washing (1.15N), stirring 500ml for 5 minutes, soaking for 3 hours, washing with waste acid liquor COD < 50mg/l for 6 times, 500ml each time, COD < 50 mg/l.

Wherein the alkali is sodium hydroxide; the acid is hydrochloric acid;

macroporous resin 2 desorbs as in examples 1-2.

Examples 6 to 8

	COD of inlet water	Water inflow	COD of effluent
				Example 6	165mg/L	50L	20.5mg/L
Example 7	165mg/L	200L	24.2mg/L
				Example 8	165mg/L	300L	47.4mg/L

SD-300 resin desorption in examples 6 to 8

Desorbing by using macroporous resin 1:

1. pouring the resin into a beaker and 500ml of 1.2N liquid alkali, stirring for 10 minutes, and soaking for 24 hours until the residual alkali is 0.77N, COD10205 mg/l; washing with 500ml water for 8 times; the 1 st COD 4444mg/l, the 2 nd COD 2702mg/l, the 3 rd COD 1578mg/l, the 4 th COD 1220mg/l, the 5 th COD 988mg/l, the 6 th COD 773mg/l, the 7 th COD 610mg/l and the 3 rd COD 445 mg/l.

2. Acid washing, 1.15N, stirring 500ml for 5 minutes, soaking for 3 hours, washing with waste acid solution COD < 50mg/l for 4 times, 500ml each time.

3. 4500ml of waste alkali and 2500ml of waste acid are produced in the desorption step.

Wherein the alkali is sodium hydroxide; the acid is hydrochloric acid;

the macroporous resin 2 desorption procedure was the same as in example 1-2.

Examples 9 to 11

	COD of inlet water	Water inflow	COD of effluent
				Example 9	160mg/L	50L	18.5mg/L
Example 10	160mg/L	200L	20.8mg/L
				Example 11	160mg/L	300L	36.6mg/L

SD-300 resin desorption in examples 9-11

Desorbing by using macroporous resin 1:

1. pouring the resin into a beaker and 500ml of 1.2N liquid alkali, stirring for 10 minutes, and soaking for 22 hours until 0.67N, COD 8630mg/l of alkali is left; washing with 500ml water for 8 times; the 1 st COD 4400mg/l, the 2 nd COD 2836mg/l, the 3 rd COD 1800mg/l, the 4 th COD 1401mg/l, the 5 th COD 1126mg/l, the 6 th COD 943mg/l, the 7 th COD 731mg/l and the 8 th COD 506 mg/l.

2. Acid washing, 1.15N, stirring 500ml for 5 minutes, soaking for 4 hours, washing with water for 3 times, 500ml each time, wherein COD in the waste acid liquor is less than 50 mg/l.

3. 4500ml of waste alkali and 2000ml of waste acid are produced in the desorption step.

Wherein the alkali is sodium hydroxide; the acid is hydrochloric acid;

the macroporous resin 2 desorption procedure was the same as in example 1-2.

As can be seen from the results of examples 1 to 11, the macroporous resin 1, which is subjected to the liquid caustic treatment by desorption, requires immersion for 18 to 24 hours; the macroporous resin 2 is used for desorbing liquid alkali and needs to be soaked for about 30 minutes; all acid washing treatments require soaking for 3-4 hours.

The above description further describes a specific embodiment of the present invention with reference to specific examples, which are intended for the detailed description of the present invention and are not intended to limit the present invention. The above-mentioned embodiments are merely descriptions of the preferred embodiments of the present invention, and do not limit the technical concept and the protection scope of the present invention, and various modifications and improvements made to the technical concept by those skilled in the art without departing from the design concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for removing COD in high-salinity wastewater is characterized by comprising the following steps: first-stage treatment, membrane filtration, and removal of suspended solid pollutants in the sewage; the sewage after primary treatment belongs to the pretreated wastewater of secondary treatment;

secondary treatment, namely performing primary resin adsorption to remove organic matters which are in a colloid state and a dissolved state and are partially difficult to degrade in the sewage;

and third-stage treatment, namely, second resin adsorption, and further treatment of refractory organic matters and soluble inorganic matters causing water eutrophication.

2. The method according to claim 1, wherein the highest acidity of the wastewater is pH 2.

3. The method for removing COD in high salinity wastewater according to claim 1, characterized in that the resin is an aromatic macroporous adsorption resin.

4. The method for removing COD in high salinity wastewater according to claim 3, characterized in that the resin is aromatic macroporous adsorption resin SD-300 resin with styrene skeleton.

5. The method according to claim 1, wherein the membrane has a pore size of 0.1-0.5 μm.

6. The method according to claim 5, wherein the membrane has a pore size of 0.12-0.3 μm.

7. The method according to claim 6, wherein the membrane has a pore size of 0.15 μm.

8. The method for removing COD in high salinity wastewater according to claim 1, characterized in that the method further comprises desorption treatment, after the resin is saturated by adsorption, treatment is carried out by using a desorption agent, and the desorption agent comprises acid, alkali and water.

9. The method according to claim 8, wherein the desorption treatment comprises washing the resin with 5% sodium hydroxide solution, mixing the washed waste lye with the ortho-wastewater at a ratio of about 0.5mol/L, filtering, treating the filtered wastewater with the neutralized residue, washing the resin with pure water for 8 times, and treating the washed wastewater with the original wastewater.

10. The method for removing COD in high salinity wastewater according to claim 9, characterized in that the desorption treatment further comprises washing the resin after the alkaline washing with hydrochloric acid of about 1N, washing the washed spent acid solution into the original wastewater for treatment, washing the resin with pure water for 6 times, and treating the washed wastewater into the original wastewater; and recycling the cleaned resin.