CN107721081A - A kind of innocuity disposal system and method for chlorophenols waste water - Google Patents

Abstract

The invention discloses a kind of Harmless and Comprehensive Disposal system and method for chlorophenols waste water, processing system includes pretreatment unit, wet oxidation reaction device, waste water deployment device, biochemical treatment apparatus and exhaust gas processing device etc., method using said system processing chlorophenols waste water includes corresponding processing step, wherein, preprocessing process mainly to remove the suspension in waste water, pH regulation, with biochemical treatment caused by excess sludge mixed；The mixture of chlorophenols waste water and biochemical sludge carries out wet oxidation processing, and through peroxide degradation, chlorophenol conversion ratio is more than 85%, and the biochemical index of waste water is improved to more than 0.4；Tail gas caused by wet oxidation enters biofilter and carries out vent gas treatment, purifying harmful gas；Wet oxidation water outlet enters membrane bioreactor after waste water is allocated and carries out biochemical treatment, removes organic pollution remaining in waste water.Through integrated artistic, the COD clearances of Chlorophenol are more than 95%；The problem of technique is easily operated, and water quality safety is high, stable effluent quality, and emission-free discharge and sludge produce.

Description

A harmless treatment system and method for chlorophenol wastewater

technical field

The invention relates to wastewater treatment technology, in particular to a harmless treatment system and method for chlorophenol wastewater.

Background technique

With the continuous development of my country's industrialization, more and more compounds are used in various industries. As a class of substances with broad-spectrum bactericidal and insecticidal effects, chlorophenol compounds are widely used in industries such as preservatives, rust inhibitors, insecticides, fungicides, and herbicides. The use of a large amount of chlorophenols leads to their inevitable entry into the environmental water. Since chlorophenol compounds have strong bactericidal activity, biological toxicity, carcinogenicity, teratogenicity and mutagenicity and other "three-cause" effects, and are difficult to degrade in the environment, they can continuously accumulate in organisms through food chains and food webs, posing a serious threat human health and the ecological environment. Therefore, it is necessary to effectively treat chlorophenol-containing wastewater.

Chlorophenols have low biodegradability due to their specific aromatic ring structure and the presence of chlorinated atoms, so it is difficult to remove them by conventional biological treatment. Therefore, the existing biodegradable chlorophenol compounds need to be degraded by specific bacterial flora, and the operating conditions are harsh, such as CN103736241A. Advanced oxidation technology is often used as a process for the treatment of chlorophenol-containing wastewater. Among them, the effect of direct ozone oxidation on the oxidation of chlorophenols is poor, and the processing capacity is weak; the catalytic oxidation causes serious pollution and is expensive due to the extensive use of catalysts; and although the photocatalytic oxidation method avoids the pollution problem of the catalyst, it is not suitable for transparent The industrial wastewater with poor light rate has poor treatment effect. At the same time, although the advanced oxidation technology has a certain degradation efficiency for chlorophenols, it will produce a large number of intermediate products or by-products with different structures during the oxidation process, some of which are far more toxic than the original pollutants. It is difficult to truly achieve the harmless treatment of chlorophenol wastewater. Therefore, the current single treatment technology cannot fully achieve the purpose of removing chlorophenol pollutants in water.

Contents of the invention

In view of the defects in the current chlorophenol wastewater treatment process, such as poor biodegradability of wastewater, many intermediate products in the treatment process, and incomplete removal, the present invention provides a harmless treatment system for chlorophenol wastewater and a corresponding treatment method.

The harmless treatment system of chlorophenol wastewater according to the present invention includes a pretreatment device, a wet oxidation reaction device, a wastewater preparation device and a biochemical treatment device connected in sequence through pipelines, wherein the liquid of the wet oxidation reaction device The outlet of the phase product and solid residue is connected with the inlet of the wastewater preparation device, the gas phase product outlet of the wet oxidation reaction device is directly connected to the tail gas treatment device through a pipeline and discharged after treatment, and the effluent treated by the biochemical treatment device is directly discharged. The sludge generated by the treatment device is directly introduced into the wet oxidation reaction device through the pipeline.

Wherein, a mixer can also be added between the pretreatment device and the wet oxidation reaction device, and the biochemical sludge exported from the biochemical treatment device is first introduced into the mixer and mixed evenly with the filtrate pretreated by the pretreatment device, and then Introduce a wet oxidation reaction device.

The biochemical treatment device is a membrane bioreactor. The sludge concentration of the membrane bioreactor is 5000-10000mg/L, the aeration rate is 20-40L/h, and the hydraulic retention time is 1-5h.

The tail gas treatment device is a biological filter. The filler in the biofilter is one or more of peat, sawdust, porous ceramics, and granular activated carbon, and the treatment temperature is 25-35° C. and the pH is 7-8.

Preferably, a circulation pump is connected in series on the sludge outlet pipeline of the biochemical treatment device.

Utilize the method for above-mentioned harmless treatment system to process chlorophenol waste water, comprise the following steps:

(1) Pretreatment: import the chlorophenol waste water to be treated into the pretreatment device, add flocculant, filter to remove suspended solids and particulate matter after stirring, and adjust the pH of the filtrate to be 7-9; then the filtrate and step (4) biochemical treatment The resulting sludge is mixed to obtain a mixture;

(2) Wet oxidation: the mixture pretreated in step (1) is transported to the wet oxidation reaction device, and a catalyst is added to react, and the organic pollutants in the mixture are degraded, forming gas phase and liquid phase products and a small amount of solid residue; reaction After completion, the gas phase products are discharged into the tail gas treatment device for purification and discharged, and the liquid phase products and solid residues enter the next step of treatment;

(3) Wastewater deployment: transport the liquid-phase product and solid residue produced by the wet oxidation reaction in step (2) to the wastewater preparation device, precipitate and remove the solid residue, and then adjust the pH of the wastewater to 6-8, the temperature to 20-35°C, and the less than 2% salt;

(4) Biochemical treatment: the wastewater prepared in step (3) is introduced into the biochemical treatment device, the treated effluent is discharged directly, and the biochemical sludge produced after the treatment is mixed with the filtrate obtained from the pretreatment in step (1). Introduce a wet oxidation reaction device.

In step (1), the flocculant is one or more of FeCl ₃ , AlCl ₃ , sodium polyacrylate and polyacrylamide, and the dosage is 0.1%-0.3% of the mass of chlorophenol wastewater to be treated.

In step (1), according to the actual situation, acid or alkali is added to the filtrate to adjust the pH to 7-9.

In step (2), the catalyst is one or more of metal salt solutions such as Cu, Fe, Mn, Ce and Ti, and the addition amount is 0.1%- 0.2%.

In step (2), the wet oxidation reaction conditions are: reaction temperature 250-320° C., reaction pressure 5-8 MPa, reaction time 0.5-2 h, the oxidant used is oxygen, and the oxidation coefficient is 1.2-1.5. The wet oxidation reaction device is a continuous reaction device, which can realize continuous feeding and discharging. The wet oxidation reaction device uses an oxygen generator to produce high-purity oxygen on-site with air as a raw material for wet oxidation reaction, and the oxygen purity is >90%. The invention adopts a continuous device to realize continuous feeding and discharging, which is beneficial to industrial application; adopts an oxygen generator to produce high-purity oxygen on site, which is beneficial to improving the pollution removal rate and reducing energy consumption.

In step (2), the tail gas treatment device is a biological filter, which is directly discharged after purifying the harmful gas. Further, the filler in the biofilter is one or more of peat, sawdust, porous ceramics, and granular activated carbon, and the treatment temperature is 25-35°C and the pH is 7-8.

In step (4), the biochemical treatment system is a membrane bioreactor to further remove organic pollutants in the water, wherein the sludge concentration of the membrane bioreactor is 5000-10000mg/L, and the aeration rate is 20-40L/h , The hydraulic retention time is 1-5h.

In the above comprehensive treatment method, the reaction material of wet oxidation is a mixture of chlorophenol wastewater and biochemical sludge, and the biodegradability of the effluent after wet oxidation treatment is ≥0.4. After the overall process, the conversion rate of chlorophenol is more than 99%, and the COD removal rate of chlorophenol wastewater is more than 95%.

Based on the above, it can be seen that the harmless treatment method of chlorophenol wastewater provided by the present invention is a combined process of "pretreatment + wet oxidation + deployment + biochemistry + tail gas treatment". The wet oxidation method is used to oxidize and degrade chlorophenol wastewater. Oxidize chlorophenols into small molecular organic compounds to improve their biodegradability; use membrane bioreactor to treat the wet oxidation effluent with high biodegradability, and further remove organic pollutants in the water body, so that chlorophenols can be completely removed. The excess sludge produced by the biochemical method is mixed with chlorophenol wastewater for wet oxidation treatment; the tail gas produced by wet oxidation is purified by a biological filter.

Beneficial effects: Compared with the prior art, the comprehensive treatment method described in this application has the following advantages:

(1) The use of traditional high-level oxidation treatment chemicals such as Fenton is large, and there is a lot of iron sludge, which is difficult to clean up. However, the present invention uses a wet oxidation process to oxidize and degrade chlorophenol wastewater, reducing the amount of chemicals and sludge production;

(2) the oxidation effect of traditional advanced oxidation process to chlorophenol waste water is not good, and the conversion ratio of wet type oxidation process that the present invention adopts to chlorophenol ≥ 85%, chlorophenol is decomposed into small molecule carboxylic acid and chloride ion, The oxidation effect is good, which greatly improves the biodegradability of wastewater, and the biodegradability of wet oxidation effluent is ≥0.4; the wet oxidation reaction device used is a continuous reaction device, which can realize continuous feeding and discharging, and is convenient for large-scale commercial application.

(3) The present invention combines the wet oxidation process with the membrane bioreactor, which can greatly reduce the residual organic pollutants in the wastewater, the conversion rate of chlorophenols is ≥ 99%, the COD removal rate is ≥ 95%, and the water safety risk is reduced;

(4) The combination of the wet oxidation process provided by the present invention and the membrane bioreactor reduces the residence time of wastewater, is easy to operate, and has high water quality standards and stable effluent quality;

(5) The present invention mixes the pretreated chlorophenol waste water with the sludge produced in the biochemical treatment process, and performs wet oxidation treatment together, which reduces the treatment and disposal costs of the biochemical sludge;

(6) The combination of different processes is used to improve the degradation efficiency of chlorophenols in wastewater, reduce the production of intermediate products, and reduce the risk of toxicity to achieve the purpose of harmlessness, which meets the requirements of green environmental protection.

Description of drawings

Figure 1 is a schematic diagram of a harmless treatment system for chlorophenol wastewater.

detailed description

In order to make the objects and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with examples.

Example 1

The harmless treatment system of chlorophenol waste water as shown in Figure 1 includes a pretreatment device, a wet oxidation reaction device, a waste water deployment device and a biochemical treatment device connected in sequence through pipelines, wherein the wet oxidation reaction device The liquid phase product and the solid residue outlet are connected to the inlet of the waste water preparation device, the gas phase product outlet of the wet oxidation reaction device is directly connected to the tail gas treatment device through a pipeline and discharged after treatment, and the effluent treated by the biochemical treatment device is directly discharged. The sludge generated by the biochemical treatment device is directly introduced into the wet oxidation reaction device through the pipeline. The biochemical treatment device is a membrane bioreactor, and the tail gas treatment device is a biological filter.

Example 2

The system described in Example 1 was adopted for the harmless treatment of chlorophenol wastewater.

The wastewater produced by a chemical factory has a pH value of 2.28 and a COD of 9100mg/L, which contains 125.8mg/L2,4-dichlorophenol, 127.2mg/L2,4,6-trichlorophenol, 75.4mg/L2,3, 5,6-Tetrachlorophenol. Wastewater is introduced into the pretreatment device, 0.1% sodium polyacrylate is added, flocculated and stirred, and then filtered to remove suspended solids in the water body, and 30% liquid alkali is added to adjust the pH value of the water body to 7; Sludge mixed, introduced into wet oxidation reaction device, adding 0.1% FeCl ₃ as catalyst, oxygen as oxidant, oxygen purity 93%, reaction temperature 250°C, reaction pressure 5MPa, reaction time 0.5h, after wet oxidation system The conversion rate of chlorophenols is 85.3%, and the biodegradability of the effluent is 0.4; the wet oxidation effluent enters the wastewater preparation device, adjusts the pH of the wastewater to 6, the temperature is 20°C, and the salt content is 1%, and then it is introduced into the membrane organism In the reactor, the sludge concentration of the membrane bioreaction system is 5000mg/L, the aeration rate is 20L/h, and the hydraulic retention time is 1h; the excess sludge generated by the membrane bioreaction system is introduced into the wet oxidation reaction device for treatment; the wet oxidation The tail gas is introduced into the biological filter for tail gas treatment. The filler of the biological filter is peat, the temperature is 25°C, and the pH is 7. After being treated by this process, the COD removal rate of the chlorophenol wastewater is 95.7%, and the removal efficiency of chlorophenol substances is 99.5%, reaching the third-level standard of the "Comprehensive Wastewater Discharge Standard" GB8978-1996, meeting the sewage treatment of the chemical industry park Factory takeover requirements.

Comparative example 1

The waste water to be treated in this comparative example is the same as that in Example 2, and the specific operation differs from that in Example 2 in that only wet oxidation is performed, and no biochemical treatment is performed. After the wet oxidation system, the conversion rate of chlorophenols is 82.1%, the biodegradability of the effluent is 0.4, and the COD removal rate is only 75.5%, which cannot meet the takeover requirements of the sewage treatment plant in the chemical industry park.

Comparative example 2

The waste water to be treated in this comparative example is the same as that in Example 2, and the specific operation differs from that in Example 2 in that air is used as the oxidant. After the overall process treatment, the COD removal rate of the chlorophenol wastewater was 91.2%, and the removal efficiency of chlorophenol substances was 95.0%, which did not meet the takeover requirements of the sewage treatment plant in the chemical industry park.

Example 3

The wastewater produced by a chemical factory has a pH value of 4.08 and a COD of 21200mg/L, which contains 132.2mg/L 2,4,6-trichlorophenol, 327.4mg/L 2,3,5,6-tetrachlorophenol, 260.3mg /L pentachlorophenol. Wastewater is introduced into the pretreatment device, 0.1% polyacrylamide is added for flocculation and stirring, and then filtered to remove suspended solids in the water body, and NaOH is added to adjust the pH value of the water body to 8; the waste water is mixed with the remaining sludge produced by biochemical reactions, and introduced into the wet Oxidation reaction device, add 0.15% MnCl ₂ as catalyst, oxygen as oxidant, oxygen purity 95%, reaction temperature 280°C, reaction pressure 7MPa, reaction time 1h, conversion rate of chlorophenols after wet oxidation system The biodegradability of the water body is 89.8%, and the biodegradability of the water body is 0.5; the wet oxidation effluent enters the wastewater preparation device, adjusts the pH of the wastewater to 7, the temperature is 25°C, and the salt content is 1.5%, and then it is introduced into the membrane bioreactor, the membrane bioreaction system The sludge concentration is 7500mg/L, the aeration rate is 30L/h, and the hydraulic retention time is 3h; the excess sludge produced by the membrane bioreactor system is introduced into the wet oxidation reaction device for treatment; the tail gas from the wet oxidation is introduced into the biofilter for tail gas For treatment, the filler of the biofilter is sawdust, the temperature is 30°C, and the pH is 8. After being treated by this system, the COD removal rate of the chlorophenol wastewater is 97.6%, and the removal efficiency of chlorophenol substances is 99.8%, reaching the third-level standard of the "Comprehensive Wastewater Discharge Standard" GB8978-1996, meeting the sewage treatment of chemical industry parks Factory takeover requirements.

Example 4

The wastewater produced by a chemical factory has a pH value of 6.67 and a COD of 39700mg/L, which contains 250.5mg/L 2-chlorophenol, 148.5mg/L 2,4-dichlorophenol, 326mg/L 2,6-dichlorophenol, 222.6mg/L pentachlorophenol. Wastewater is introduced into the pretreatment device, 0.3% AlCl ₃ is added to flocculate and stir, and then filtered to remove suspended solids in the water body, and NaOH is added to adjust the pH value of the water body to 9; the waste water is mixed with the remaining sludge produced by biochemical reactions, and introduced into wet oxidation Reaction device, add 0.2% Cu(NO ₃ ) ₂ as catalyst, oxygen as oxidant, oxygen purity 91%, reaction temperature 320°C, reaction pressure 8MPa, reaction time 2h, chlorophenols after wet oxidation system The conversion rate of the water body is 94.7%, and the biodegradability of the water body is 0.6; the wet oxidation effluent enters the wastewater preparation device, adjusts the pH of the wastewater to 8, the temperature is 30°C, and the salt content is 0.4%, and then it is introduced into the membrane bioreactor. The sludge concentration of the biological reaction system is 10000mg/L, the aeration rate is 40L/h, and the hydraulic retention time is 5h. The excess sludge produced by the membrane biological reaction system is introduced into the wet oxidation reaction device for treatment; the tail gas of the wet oxidation is introduced into the biofilter for tail gas treatment. The biofilter is filled with porous ceramics at a temperature of 35°C and a pH of 7.5. After being treated by this system, the COD removal rate of the chlorophenol wastewater is 98.8%, and the removal efficiency of chlorophenol substances is 99.9%, reaching the third-level standard of the "Comprehensive Wastewater Discharge Standard" GB8978-1996, meeting the sewage treatment of chemical industry parks Factory takeover requirements.

Claims (7)

1. a kind of innocuity disposal system of chlorophenols waste water, it is characterised in that including the pretreatment being sequentially communicated by pipeline Device, wet oxidation reaction device, waste water deployment device and biochemical treatment apparatus, wherein, the wet oxidation reaction device Liquid product and solid residue outlet be connected with the entrance of waste water deployment device, the gas phase of the wet oxidation reaction device Product exit after pipeline communication to exhaust gas processing device processing directly by discharging, the water outlet after the biochemical treatment apparatus processing It is expelled directly out, sludge caused by biochemical treatment apparatus processing is then introduced directly into wet oxidation reaction device by pipeline.

2. utilize the method for system processing chlorophenols waste water described in claim 1, it is characterised in that comprise the following steps：

(1) pre-process：Pending chlorophenols waste water is imported into pretreatment unit, adds flocculant, is filtered off after stirring except outstanding Float and particulate matter, regulation filtrate pH is 7-9, and then filtrate is mixed with sludge caused by step (4) biochemical treatment, is mixed Compound；

(2) wet oxidation：Mixture after being pre-processed via step (1) is transported to wet oxidation reaction device, addition is urged Agent is reacted, and the organic pollution in mixture is degraded, and forms gas phase and liquid product and a small amount of solid residue；Reaction After the completion of, gas-phase product is discharged after being discharged into exhaust gas processing device purification, and liquid product and solid residue enter processing in next step；

(3) waste water is allocated：Liquid product and solid residue caused by step (2) wet oxidation reaction are delivered to waste water allotment dress Put, precipitation removes solid residue, then adjusts wastewater pH to 6-8, temperature to 20-35 DEG C, salt content and is less than 2%；

(4) biochemical treatment：Waste water after being allocated via step (3) imports biochemical treatment apparatus, and the water outlet after processing is directly arranged Put, the filtrate that caused biochemical sludge then obtains with step (1) pretreatment after processing imports wet oxidation reaction in the lump after mixing Device.

3. chlorophenols method of wastewater treatment according to claim 2, it is characterised in that in step (1), the flocculant is FeCl₃、AlCl₃, Sodium Polyacrylate and polyacrylamide one or more therein, dosage be pending chlorophenols waste water matter The 0.1%-0.3% of amount.

4. chlorophenols method of wastewater treatment according to claim 2, it is characterised in that in step (2), the catalyst is One or more in the metal salt solutions such as Cu, Fe, Mn, Ce and Ti, addition are pending waste water and biochemical sludge mixture The 0.1%-0.2% of quality.

5. chlorophenols method of wastewater treatment according to claim 2, it is characterised in that in step (2), the wet oxidation Reaction condition is：250-320 DEG C of reaction temperature, reaction pressure 5-8MPa, reaction time 0.5-2h, oxidant used are oxygen, Oxygen purity>90%, coefficient of oxidation 1.2-1.5.

6. the integrated conduct method of chlorophenols waste water according to claim 2, it is characterised in that in step (2), the tail Flash Gas Compression Skid System is biofilter, and the filler in biofilter is peat, one kind in wood chip, porous ceramics, granular activated carbon Or it is several, treatment temperature is 25-35 DEG C, pH 7-8.

7. the integrated conduct method of chlorophenols waste water according to claim 2, it is characterised in that in step (4), the life Change processing system is membrane bioreactor, the organic pollution further gone in water removal, wherein, membrane bioreactor sludge concentration For 5000-10000mg/L, aeration quantity 20-40L/h, hydraulic detention time 1-5h.