CN102633410A - Process for recycling and processing hyperhaline reverse osmosis concentrated water - Google Patents

Abstract

The invention relates to the technical field of sewage treatment in environmental engineering, in particular to a treatment and reuse process for high-salt reverse osmosis concentrated water generated in the sewage regeneration process. It includes photocatalytic oxidation treatment: photocatalytic oxidation reaction of high-salt reverse osmosis concentrated water; biochemical reaction treatment: biochemical reaction of effluent after photocatalytic oxidation reaction; desalination treatment and ultrafiltration purification treatment. The beneficial effects of the present invention are: the treatment process has high pollutant removal efficiency; the resource utilization of high-salt reverse osmosis concentrated water can be realized; it can be applied to the treatment of other high-salt wastewater with low organic matter concentration and is difficult to biochemical; it can overcome activated sludge Sludge bulking and sludge floating are easy to occur in the process of the method, and its operation is stable, the impact load resistance is strong, it is more economical and energy-saving, and it has a certain function of nitrification and denitrification, which can realize closed operation and prevent odor.

Description

Reuse Treatment Process of High Salt Reverse Osmosis Concentrated Water

technical field

The invention relates to the technical field of sewage treatment in environmental engineering, in particular to a treatment and reuse process for high-salt reverse osmosis concentrated water generated in the sewage regeneration process.

Background technique

As a high-efficiency, energy-saving and environmentally friendly membrane separation technology, reverse osmosis membrane (RO) is widely used in the fields of medicine, food, beverage, seawater desalination, etc. In the field of water treatment, it is mainly used for the purification, purification, Desalination of seawater and brackish water and regeneration and reuse of secondary effluent from sewage plants. Since reverse osmosis technology is the finest physical separation process, in the process of preparing recycled water, concentrated water (RO concentrate) containing high concentrations of salt and dissolved organic pollutants (DOM) will be produced. Because reverse osmosis concentrated water production accounts for 1/3 to 1/5 of the total raw water, a large amount of high-salt concentrated water is discharged into the sewage plant as discarded water, which not only poses a serious threat to the normal operation of the sewage treatment plant, but also contains high The concentration of salinity will also damage the ecosystem of the receiving water body, and eventually lead to the degradation of the ecological function of the environment around the water body. Many studies have shown that the presence of high-concentration salt has a significant inhibitory effect on biological activity, and when the salt content of water is above 3%, its biological treatment efficiency is significantly reduced. The superposition of high salinity and refractory characteristics makes RO concentrated water treated by conventional biochemical methods unable to meet the quality requirements or discharge standards for reused water. However, as reported in the 1st issue of "Environmental Science" in 2000 and the 2nd issue of "Industrial Water Treatment" in 2005, as long as the system goes through a certain period of domestication or adds halophilic bacteria or halophilic bacteria that are screened to the system, biochemical methods can also be used. Can handle high salinity wastewater.

The existing technology is mainly aimed at the treatment of high-salt and high-concentration organic wastewater, and generally adopts the improved activated sludge process, which has high organic matter removal efficiency. However, the amount of excess sludge produced by the activated sludge method is large, and sludge bulking is prone to occur. For high-salt wastewater with a relatively low concentration of organic matter, the purification efficiency is low.

Contents of the invention

The invention aims to propose a high-salt reverse osmosis concentrated water purification and reuse process, through the synergistic effect of advanced oxidation and bio-augmentation technology, the treated water can reach the reuse standard, and the resource utilization of reverse osmosis concentrated water can be realized.

The technical solution of the present invention is: the reuse treatment process of high-salt reverse osmosis concentrated water, comprising the following steps:

(1) Photocatalytic oxidation treatment: The high-salt reverse osmosis concentrated water is subjected to photocatalytic oxidation reaction. The light for the photocatalytic oxidation reaction is ultraviolet light, and the light source is an ultraviolet lamp; the photocatalytic oxidant is H ₂ O ₂ , and the dosage per liter of concentrated water is 1-6mM, preferably 4mM. The photolysis reaction time is 30-60 minutes, preferably 30 minutes. The device used is a photocatalytic oxidation reactor.

The power of the ultraviolet lamp is 39W, and the wavelength of ultraviolet light is 254nm.

The function of step (1) is: the macromolecular organic matter in the high-salt reverse osmosis concentrated water is gradually converted into small molecular organic matter through photolysis reaction, and the biochemical property of the reverse osmosis concentrated water is improved. After the treatment in step (1), the COD removal rate is 11.1% to 22.5%, and the effluent does not meet the water quality standard for reclaimed water used as an industrial water source.

(2) Biochemical treatment: the effluent after the photocatalytic oxidation reaction in step (1) is subjected to a biochemical reaction. The device used is a biological activated carbon reactor.

The empty bed contact time of the biological activated carbon reactor is 30 to 180 minutes; the biological activated carbon reactor operates intermittently, and the aeration reaction time of each reaction cycle is 9 to 10 hours. After stopping the aeration for 2 to 3 hours, the aeration reaction is carried out again. , cycle the aeration-stop aeration process.

The activated carbon in the biological activated carbon reactor adopts columnar granular activated carbon. Columnar granular activated carbon has a large specific surface area, developed pore structure, excellent adsorption performance and mechanical and physical properties, so it is easy for microorganisms to attach. Under the synergy of biodegradation and physical adsorption, organic pollutants are removed. Due to the degradation of the attached microorganisms, the activated carbon can be regenerated while adsorbing, thus greatly extending its service life.

The biofilm attached to the activated carbon in the biological activated carbon reactor is mainly composed of salt-tolerant bacteria and a small amount of protozoa. These salt-tolerant microorganisms can oxidize and decompose organic pollutants under high-salt conditions, and have a strong ability to remove organic matter.

The salt-tolerant flora is mainly composed of Pseudomonas, Bacillus, fungi, filamentous bacteria, etc. to form a dense gelatinous group, and a small amount of microscopic animals such as ciliates, wandering insects, etc. are also mixed. It is derived from the return activated sludge of urban sewage treatment plants. After intensive domestication and cultivation, it attaches to activated carbon particles to form an active biofilm.

The function of step (2) is to further reduce the concentration of organic matter through the metabolism of the salt-tolerant flora. After the treatment in step (2), the COD removal rate is 49.3%-91.2%, and the effluent reaches the water quality standard for reclaimed water used as an industrial water source.

(3) Desalination treatment: the effluent after the biochemical reaction in step (2) is subjected to desalination treatment, and the device used is a low-voltage carbon adsorption reactor. The main function is to remove dissolved solids in water. After this step, the TDS value of total dissolved solids in the effluent is 482-864 mg/L, reaching the water quality standard for reclaimed water used as a source of industrial water.

(4) Ultrafiltration and purification treatment: the effluent after the desalination treatment in step (3) is subjected to ultrafiltration and purification treatment, and the effluent is reused after reaching the standard.

The effluent treated in step (4) reaches the water quality standard for reclaimed water to be used as an industrial water source.

The indicators of the high-salt reverse osmosis concentrated water are as follows: the pH value is 8-9, the COD value is 200-300 mg/L, the dissolved organic carbon DOC value is 40-50 mg/L, and the total dissolved solids TDS value is 2000-300 mg/L. 4000mg/L, the chromaticity value is 120-200 (Pt-Co).

Compared with the prior art, the beneficial effect of the present invention is that after the high-salt reverse osmosis concentrated water is treated, the effluent can be reused for industrial production, which has important practical significance for saving water resources and protecting the water body environment. Technology provided by the invention has the following advantages:

1. The treatment process has high pollutant removal efficiency, the COD removal rate can reach about 90%, the TDS removal rate can reach more than 80%, and the DOC removal rate can reach more than 90%;

2. It can realize the recycling of high-salt reverse osmosis concentrated water, and the treated effluent can meet the water quality standard of reclaimed water used as industrial water source, and can be recycled for industrial cooling water replenishment water;

3. It can be applied to the treatment of other high-salt wastewater with low organic concentration and difficult to biochemical;

4. It can overcome the problems of sludge bulking and sludge floating that are easy to occur in the activated sludge process. It has stable operation, strong impact load resistance, more economical and energy-saving, has a certain nitrification and denitrification function, and can realize closed operation. , Prevent odor, etc.

Description of drawings

Fig. 1 is a schematic diagram of a process flow of the present invention;

Fig. 2 is the COD removal result schematic diagram of high-salt reverse osmosis concentrated water in comparative example 1 of the present invention;

Fig. 3 is a schematic diagram of the COD removal results of high-salt reverse osmosis concentrated water in Comparative Example 2 of the present invention.

Among them, in Figure 1: 1. Regulating tank, 2. Photocatalytic oxidation reactor, 3. Peristaltic pump, 4. Bioactive carbon reactor, 5. Air compressor, 6. Low voltage carbon adsorption reactor, 7. Ultrafiltration Device, 8, outlet water storage tank.

Detailed ways

The present invention will be described in detail below by means of drawings and examples.

Example 1:

Indicators of high-salt reverse osmosis concentrated water to be treated: pH value is 8.6, COD value is 207mg/L, dissolved organic carbon DOC value is 41.6mg/L, total dissolved solids TDS value is 3180mg/L, chromaticity value is 172 (Pt-Co). 5 liters of treated water.

As shown in Figure 1, the following steps are used to reuse the high-salt reverse osmosis concentrated water:

1. The high-salt reverse osmosis concentrated water first enters the regulating tank to adjust the water volume, so as to ensure that the whole device can continuously enter water and operate stably. The volume of the adjustment tank is 10 liters. The regulating pool is used to adjust the water intake to ensure continuous water intake and stable operation of the device.

2. The effluent from the adjustment pool is pumped into the photocatalytic oxidation reactor by the peristaltic pump, and 0.068 mg of photocatalytic oxidant H ₂ O ₂ with a concentration of 50% is added. After 30 minutes of UV photolysis reaction, the macromolecular organic matter is gradually converted into small molecular organic matter. While removing part of the organic matter, the biodegradability of the wastewater is improved. The peristaltic pump is used to drive the effluent water from the regulating tank into the photocatalytic oxidation reactor. The function of the photocatalytic oxidation reactor is to use the photolysis reaction to convert the macromolecular organic matter in the high-salt reverse osmosis concentrated water into small molecular organic matter, improve the biodegradability of the reverse osmosis concentrated water, and remove some organic pollutants.

3. After photocatalytic oxidation, the effluent flows into the biological activated carbon reactor for biochemical reaction treatment. An air compressor is connected to the bottom of the bioactivated carbon reactor to provide compressed air to supply the oxygen required for the biofilm biochemical reaction of the bioactivated carbon reactor.

The activated carbon in the biological activated carbon reactor adopts columnar granular activated carbon.

The biofilm attached to activated carbon is mainly composed of salt-tolerant bacteria, mixed with a small amount of protozoa. The activated sludge used in the film hanging comes from the return activated sludge of the sewage treatment plant.

The contact time of the empty bed of the biological activated carbon reactor is 30 minutes, and the biological activated carbon reactor operates intermittently. The aeration reaction time of each reaction cycle is 9 to 10 hours. - stop exposure process.

The main function of the biological activated carbon reactor is to further remove organic pollutants by utilizing the synergistic effect of physical adsorption of activated carbon and biochemical degradation of biofilm.

The function of the air compressor is to provide compressed air to supply the oxygen required for the biofilm biochemical reaction of the bioactivated carbon reactor.

4. The effluent from the biological activated carbon reactor enters the low-voltage carbon adsorption reactor for desalination treatment to remove most of the dissolved solids. The role of the low-voltage carbon adsorption reactor is to desalinate the effluent and remove dissolved solids in the water.

5. The effluent from the low-voltage carbon adsorption reactor enters the ultrafiltration device, and after being filtered and purified by the ultrafiltration membrane, the effluent is stored in the effluent storage tank. The effluent water reaches the water quality standard for reclaimed water used as an industrial water source, and can be reused as supplementary water for industrial cooling water. The function of the ultrafiltration device is to filter and purify the effluent through the ultrafiltration membrane.

After testing, the final effluent indicators are: pH value 8.37, COD value 105mg/L, dissolved organic carbon DOC value 12.9mg/L, total dissolved solids TDS value 570mg/L, chromaticity value 41 (Pt -Co). The COD removal rate is 49.3%, the TDS removal rate is 82.1%, and the DOC removal rate is 69.0%.

Embodiment 2: except following difference, other is the same as embodiment 1.

2. Add 0.408 mg of photocatalytic oxidant H ₂ O ₂ , and conduct UV photolysis reaction for 60 minutes.

3. The empty bed contact time of the biological activated carbon reactor is 180min.

After testing, the final effluent indicators are: pH value is 8.45, COD value is 18.3mg/L, dissolved organic carbon DOC value is 2.37mg/L, total dissolved solids TDS value is 482mg/L, chromaticity value is 29 ( Pt-Co). The COD removal rate is 91.2%, the TDS removal rate is 84.8%, and the DOC removal rate is 94.3%.

Embodiment 3: except following difference, other is with embodiment 1.

2. Add 0.272 mg of photocatalytic oxidant H ₂ O ₂ , and conduct UV photolysis reaction for 30 minutes.

3. The empty bed contact time of the biological activated carbon reactor is 60 minutes.

After testing, the final effluent indicators are: pH value is 8.46, COD value is 19.8mg/L, dissolved organic carbon DOC value is 2.87mg/L, total dissolved solids TDS value is 610mg/L, chromaticity value is 37 ( Pt-Co). The COD removal rate is 90.4%, the TDS removal rate is 80.8%, and the DOC removal rate is 93.1%.

Embodiment 4: except following difference, other is with embodiment 1.

2. Add 0.204 mg of photocatalytic oxidant H ₂ O ₂ , and react with UV photolysis for 45 minutes.

3. The empty bed contact time of the biological activated carbon reactor is 120min.

After testing, the final effluent indicators are: pH value is 8.39, COD value is 19.4mg/L, dissolved organic carbon DOC value is 2.75mg/L, total dissolved solids TDS value is 672mg/L, chromaticity value is 51( Pt-Co).

The COD removal rate is 90.6%, the TDS removal rate is 78.9%, and the DOC removal rate is 93.4%.

Embodiment 5: except following difference, other is with embodiment 1.

Indicators of high-salt reverse osmosis concentrated water to be treated: pH value is 8, COD value is 205.4mg/L, dissolved organic carbon DOC value is 40.2mg/L, total dissolved solids TDS value is 2031mg/L, chromaticity value It is 117 (Pt-Co). 5 liters of treated water.

2. Add 0.272 mg of photocatalytic oxidant H ₂ O ₂ , and conduct UV photolysis reaction for 30 minutes.

3. The empty bed contact time of the biological activated carbon reactor is 60 minutes.

After testing, the final effluent indicators are: pH value is 8.33, COD value is 19.9mg/L, dissolved organic carbon DOC value is 3.49mg/L, total dissolved solids TDS value is 532mg/L, chromaticity value is 35 ( Pt-Co). The COD removal rate is 90.3%, the TDS removal rate is 73.8%, and the DOC removal rate is 91.3%.

Embodiment 6: except following difference, other is the same as embodiment 1.

Indicators of high-salt reverse osmosis concentrated water to be treated: pH value is 9, COD value is 297.6mg/L, dissolved organic carbon DOC value is 49.4mg/L, total dissolved solids TDS value is 3977mg/L, chromaticity value It is 203 (Pt-Co). 5 liters of treated water.

2. Add 0.272 mg of photocatalytic oxidant H ₂ O ₂ , and conduct UV photolysis reaction for 30 minutes.

3. The empty bed contact time of the biological activated carbon reactor is 60 minutes.

After testing, the final effluent indicators are: pH value 8.42, COD value 29.7mg/L, dissolved organic carbon DOC value 4.05mg/L, total dissolved solids TDS value 864mg/L, chromaticity value 64 ( Pt-Co). The COD removal rate is 90.0%, the TDS removal rate is 78.3%, and the DOC removal rate is 91.8%.

Comparative example 1:

Indicators of high-salt reverse osmosis concentrated water to be treated: pH value is 8.7, COD value is 227mg/L, dissolved organic carbon DOC value is 41.6mg/L, total dissolved solids TDS value is 3180mg/L, chromaticity value is 170 (Pt-Co). 5 liters of treated water.

The high-salt reverse osmosis concentrated water undergoes desalination treatment and ultrafiltration purification treatment after being treated by the regulating tank to adjust the water volume and photocatalytic oxidation reaction, without biochemical reaction treatment.

The dosage of H ₂ O ₂ per liter of concentrated water in the photocatalytic oxidation reactor is 4mM, and the photolysis reaction time is 0min, 10min, 30min, 60min, 120min and 180min; the COD removal results are shown in Figure 2.

Figure 2 shows that after photocatalytic oxidation treatment alone, the COD removal efficiency of high-salt reverse osmosis concentrated water is only about 20%, and the effluent cannot meet the reuse requirements.

Comparative example 2:

The index of high-salt reverse osmosis concentrated water to be treated is the same as that of Comparative Example 1.

The high-salt reverse osmosis concentrated water enters the biological activated carbon reactor for biochemical reaction treatment after passing through the regulating tank to adjust the water volume, and then undergoes desalination treatment and ultrafiltration purification treatment without photocatalytic oxidation reaction treatment.

The empty bed contact time of bioactivated carbon reactor was 0min, 30min, 45min, 60min, 120min and 180min respectively. The COD removal results are shown in Figure 3.

Figure 3 shows that after biochemical reaction treatment alone, the COD removal efficiency of high-salt reverse osmosis concentrated water is only about 30%, and the effluent cannot meet the reuse requirements.

Claims (10)

1. the reuse treatment process of a high salt reverse osmosis concentrated water comprises desalting treatment and ultrafiltration purifying treatment, it is characterized in that, and is further comprising the steps of before the desalting treatment:

One, Treatment by Photocatalysis Oxidation: high salt reverse osmosis concentrated water is carried out photocatalysis oxidation reaction;

Two, biochemical reaction is handled: will carry out biochemical reaction through the water outlet behind the step 1 photocatalysis oxidation reaction.

2. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 1 is characterized in that, in the said step 1, the gloss of photocatalysis oxidation reaction is used ultraviolet, and the photolysis time is 30～60min.

3. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 2 is characterized in that, said ultraviolet uses light source to be UV-lamp; UV-lamp power is 39W, and the ultraviolet wavelength is 254nm.

4. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 1 is characterized in that, in the said step 1, H is adopted in the photochemical catalytic oxidation agent ₂O ₂, every liter of dense water dosage is 1～6mM.

5. according to the reuse treatment process of each described high salt reverse osmosis concentrated water in the claim 1～4, it is characterized in that in the said step 1, the Treatment by Photocatalysis Oxidation using appts is photocatalysis oxidation reaction device (2).

6. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 1; It is characterized in that in the said step 2, it is biological activated carbon reactor (4) that biochemical reaction is handled using appts; Said biological activated carbon reactor drum (4) periodic running, aeration-the stop process of exposing to the sun is carried out in circulation.

7. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 6 is characterized in that, the gac in the said biological activated carbon reactor drum (4) adopts the cylindrical particle gac.

8. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 6 is characterized in that, the appended microbial film of gac mainly is made up of the salt tolerant flora in the said biological activated carbon reactor drum (4).

9. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 1 is characterized in that, said desalting treatment using appts is a low voltage charcoal adsorptive reactor (6).

10. the reuse treatment process of high salt reverse osmosis concentrated water according to claim 1; It is characterized in that; The pH value of said high salt reverse osmosis concentrated water is 8～9, and the COD value is 200～300mg/L, and dissolved organic carbon DOC value is 40～50mg/L; Total dissolved solid TDS value is 2000～4000mg/L, and colourimetric number is 120～200 (Pt-Co).

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