CN110183019A - A zero-discharge treatment method for high-concentration wastewater - Google Patents

Abstract

The invention relates to a high-concentration wastewater zero-discharge treatment method. The processing method comprises the following steps: s1: adjusting the pH value of the high-concentration wastewater, adding a reducing agent, adjusting the pH value back, performing rough filtration, performing filtration again by using an MCR (modified cellulose reactor) technology, performing filtration and concentration treatment by using an STUF (super rapid diffusion) membrane system technology, and then evaporating and separating to obtain outlet water; s2: and (3) after rough filtration, filtering the effluent by using an MCR technology, then carrying out ion exchange, carrying out carbon filtration, and then sequentially treating the effluent by using a UF membrane and a three-stage reverse osmosis Ro membrane, wherein the Ro produced water is the recyclable water quality, and the Ro concentrated water is used as high-concentration wastewater to be treated by repeating S1-S2. The treatment method of the invention carries out targeted treatment on high-concentration wastewater, selects a full physical separation process technology which only introduces a small amount of external agents, can reach the industrial reuse water standard after the wastewater is treated, has low conductivity, is not easy to block membranes, has the wastewater reuse rate of more than 99 percent, only generates about 1 percent of waste liquid after the wastewater is treated, and can realize zero discharge of the wastewater.

Description

A zero-discharge treatment method for high-concentration wastewater

technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to a zero-discharge treatment method for high-concentration wastewater.

Background technique

Electroplating process wastewater contains a large amount of chelating agents, heavy metals, high COD and other pollutants. There are many types of chelation in wastewater, and it has a strong chelating ability for heavy metals such as nickel, and heavy metals such as nickel do not precipitate under alkaline conditions. Wastewater treatment is difficult, the cost is high, and the problem of not being able to meet the standards stably has always plagued the development of the electroplating industry.

At present, electroplating wastewater is generally treated by pretreatment + UF + Ro membrane method, but this method has the disadvantages of high conductivity of the produced water and easy membrane blockage.

Therefore, it is of great research significance and application value to develop a treatment process with low conductivity of the produced water, which is not easy to block the membrane and has zero discharge of wastewater.

Contents of the invention

The object of the present invention is to overcome the defects and deficiencies in the prior art, and provide a zero-discharge treatment method for high-concentration wastewater. The treatment method provided by the present invention uses pretreatment + sand carbon filtration + seawater desalination membrane to treat high-concentration wastewater, and only a small amount of foreign agents are introduced. After high-concentration wastewater is treated, it can reach the industrial reuse water standard, and the conductivity is low. , It is not easy to block the membrane, the wastewater reuse rate is over 99%, and only about 1% of the waste liquid is produced after treatment, which can realize zero discharge of high-concentration wastewater.

In order to realize the above-mentioned purpose of the invention, the present invention adopts following technical scheme:

A zero-discharge treatment method for high-concentration wastewater, comprising the steps of:

S1: After adjusting the pH of high-concentration wastewater to 3-4, after adding a reducing agent, adjust the pH to 8-10, perform coarse filtration, and use MCR technology to filter again, then use STUF membrane system technology to filter and concentrate, and then evaporate, Water is obtained after separation;

S2: After the effluent is coarsely filtered, it is filtered again by MCR technology, and then ion-exchanged by anion resin and cation resin. After carbon filtration, it is treated by UF membrane and three-stage reverse osmosis Ro membrane in turn. The Ro product water is recyclable. Water quality, Ro concentrated water is treated as high-concentration wastewater by repeating steps S1-S2.

The general process of electroplating includes the following steps: pretreatment—preplating—cleaning—electroplating—cleaning—gold/palladium—cleaning. The types and contents of chelating agents, heavy metals, COD and other pollutants in the wastewater obtained from the process steps vary greatly. If they are mixed together for treatment, more high-concentration waste liquid will be produced, resulting in high loads on special membranes and evaporation systems. Operation, operating costs increased substantially. The present invention attempts to classify the wastewater in each step, specifically including cleaning wastewater, oil and wax removal wastewater and high-concentration wastewater, wherein the cleaning wastewater is wastewater generated in each cleaning step, pH is 5-6, COD≤50mg/L, conductivity rate≤500μs/cm; the oil and wax removal wastewater is the wastewater of the pretreatment step, in which a large amount of surfactant is added, the general pH is 10-12, COD≥5000mg/L, conductivity≤1000μs/cm; other steps The waste liquid with higher COD and conductivity is treated as high-concentration wastewater. The pH of high-concentration wastewater is 5-6, COD≥3000mg/L, and conductivity≥10000μs/cm.

The treatment of high-concentration wastewater is the most difficult, mainly because high-concentration wastewater is highly organic, high-salt, and contains a small amount of fluoride and calcium carbonate. The present invention has tried a variety of treatment methods, such as UF+sea water film, but the treatment effect is average. After many studies, I finally found a better way to deal with it.

The present invention first uses a reducing agent to reduce the oxidized substances in the wastewater, and then removes large particles and sediment in the wastewater through coarse filtration, and then uses MCR technology to filter again to remove a small amount of fine suspended solids and colloidal substances that may exist in the wastewater. Then use the STUF membrane system technology to filter and separate SS, colloid, particulate matter and other pollutants in the wastewater to avoid the problems of membrane blockage and poor treatment effect in the subsequent concentration treatment; then concentrate, separate and dissolve inorganic salts and heavy metal pollutants, after After evaporation, the organic matter and conductivity of the effluent are greatly reduced, and then the large particles and sediment in the wastewater are removed by coarse filtration, and then filtered again by MCR technology. MCR technology can intercept and remove a small amount of fine suspended solids and colloidal substances that may exist in wastewater. Then carry out ion exchange to remove heavy metals and COD substances in wastewater, and the conductivity of the produced water after treatment with UF membrane and three-stage reverse osmosis Ro membrane is ≤6μs/cm, Cod≤5mg/L, which can be directly used for electroplating The workshop is used for normal production.

The high-concentration wastewater zero-discharge treatment method provided by the present invention can reach the industrial reuse water standard after treating the high-concentration wastewater, has low electrical conductivity, is not easy to block membranes, and has a wastewater reuse rate of more than 99%, and only produces about 1% after treatment. Waste liquid can realize zero discharge of high-concentration wastewater.

Preferably, the pH of the high-concentration wastewater in S1 is 5-6, COD ≥ 3000 mg/L, conductivity ≥ 10000 μs/cm.

Preferably, the STUF membrane system technology described in S1 includes STRO pre-concentration technology and DTRO secondary concentration technology.

Preferably, the evaporation waste liquid obtained by evaporation in S1 is not higher than 1%.

Preferably, activated carbon is used for coarse filtration in S2.

The present invention optimizes conventional cation resins (such as domestic cation resins, TP-207) and anion resins (such as domestic anion resins, MP-68-P2) in the field and finds that although each resin has a better ion exchange effect in the initial stage of treatment , but after long-term treatment, the loss of domestic resin (loss caused by backwashing), regeneration cost (acid-base agent dosage), and cleaning cost of resin equipment are all greater than TP-207 and MP-68-P2.

Preferably, the resin in S2 is TP-207, and the anion resin is MP-68-P2;

Preferably, the number of times of ion exchange is one or more.

Multiple sets of cation resins and anion resins can be selected for resin exchange according to needs. The order of cation resins and anion resins is not required. Multiple sets of cation resins can be used for ion exchange first, and then multiple sets of anion resins can be used for ion exchange; or First use multiple sets of anion resins for ion exchange, and then use multiple sets of cation resins for ion exchange; anion resins and cation resins can also be used alternately.

In order to fully utilize the anion resin and the cation resin and save costs, preferably, S2 further includes a step of regenerating the anion resin and the cation resin.

Regeneration treatment can be carried out in a conventional manner in the art.

Preferably, in S2, hydrochloric acid is used to regenerate the anion resin; and sodium hydroxide solution is used to regenerate the cation resin.

Preferably, the STUF membrane system technology described in S4 includes STRO pre-concentration technology and DTRO secondary concentration technology.

STRO pre-concentration technology is mainly used to separate dissolved inorganic salts and heavy metal pollutants.

DTRO secondary concentration technology is mainly used to treat concentrated water produced by STRO.

In the S2 step of the present invention, reclaimed water with 99% conductivity≤6μs/cm, COD≤5mg/L and above can be obtained after evaporation and separation treatment, and there is no more than 1% evaporation waste liquid in addition, and the evaporation waste liquid can be After concentration, other methods are processed.

Preferably, the evaporation waste liquid obtained by evaporation in S1 or S2 is not higher than 1%.

Compared with the prior art, the present invention has the following beneficial effects:

The treatment method provided by the present invention carries out targeted treatment of high-concentration wastewater, and adopts a full physical separation process technology that only introduces a small amount of foreign agents. After the wastewater is treated, it can reach the industrial reuse water standard, with low electrical conductivity, and it is not easy to block the membrane, and the wastewater can be reused. The efficiency is more than 99%, and only about 1% of waste liquid is produced after treatment, which can realize zero discharge of waste water.

Description of drawings

Fig. 1 is the process flow diagram that embodiment 1 provides.

Detailed ways

The present invention is further set forth below in conjunction with embodiment. These examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. The experimental method that does not indicate specific conditions in the following example embodiment, usually according to the conventional conditions in this field or according to the conditions suggested by the manufacturer; used raw materials, reagents, etc., if no special instructions, are available from commercial channels such as conventional markets Raw materials and reagents obtained. Any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention fall within the scope of the present invention.

The high-concentration electroplating wastewater was collected as high-concentration wastewater and tested. The results are shown in Table 1.

The water quality of high concentration wastewater in the embodiment of table 1

Example 1

This embodiment provides a zero-discharge treatment method for high-concentration wastewater, and the specific process is as follows.

The treatment of high-concentration wastewater is the most critical step, and its treatment is the most difficult, which will directly affect the water quality results of the treatment.

For high-concentration wastewater, three different treatment methods are used in this example:

1.1 Using the treatment method of pretreatment + sand carbon filter + seawater desalination membrane (denoted as scheme 1)

Pretreatment: After the high-concentration wastewater from the workshop is adjusted to a pH value of 3 to 4, it enters the reduction tank, and a reducing agent (sodium bisulfite) is added to reduce the oxidized substances in the wastewater. After that, the wastewater flows into the pH adjustment tank, and the pH is adjusted to 8 After ~9, it flows into the sedimentation tank to remove large particles and sediment in the wastewater, and then flows into the coagulation tank, adding coagulants such as ferric chloride to remove some high-level organic substances, and remove a small amount of fine particles that may exist in the wastewater. Suspended solids and colloidal substances are intercepted and enter the concentrated water collection tank; then PAM (polyacrylamide) is added from the flow into the flocculation tank, and the mud and water are separated from the flow into the sedimentation tank. Front end for reprocessing. The above pretreatment supernatant enters UF after sand carbon filtration to separate SS, colloid, particulate matter and other pollutants in the wastewater; the water produced by the UF membrane system enters the seawater desalination membrane Ro system, and the concentrated water enters the evaporation treatment pretreatment water tank. The liquid is self-suctioned by the evaporation system and enters the preheater of the three-effect evaporator. After being evaporated by the three-effect evaporator, the concentrated liquid enters the separator of the three-effect evaporator. After passing through the separator, the condensed water is pumped to the sump by the condensate pump and collected. The water pump is lifted to the activated carbon filter for coarse filtration, and the large particles and silt in the wastewater are removed and then enters the MCR's carbon filter product water collection tank; the cleaning wastewater that has been pretreated above enters the cathodic resin (TP-207 ) system, carry out resin exchange to Cu, Ge and other heavy metal pollutants in waste water; then enter the anion resin (MP-68-P2), carry out resin exchange to heavy metal pollutants such as Ni in waste water; use 35wt% respectively after resin saturation hydrochloric acid and 25wt% NaOH to regenerate the resin to ensure its exchange efficiency. In order to strictly ensure the water quality of the workshop is good, heavy metals and part of COD in the wastewater are removed (conductivity ≤ 50μs/cm, Cod ≤ 30mg/L), and then enter the reuse water system. The Ro membrane is permeated, and the final product water is directly returned to the electroplating workshop for normal production; the Ro concentrated water enters the high-concentration wastewater treatment system for retreatment. A small amount of evaporated waste liquid (about 5%) is discharged into the high-concentration waste liquid tank and entrusted to a qualified treatment company for further processing.

1.2 Pretreatment + UF + seawater desalination membrane (referred to as Scheme 2)

Pretreatment: After the high-concentration wastewater from the workshop is adjusted to a pH value of 3 to 4, it enters the reduction tank, and a reducing agent (sodium bisulfite) is added to reduce the oxidized substances in the wastewater. After that, the wastewater flows into the pH adjustment tank, and the pH is adjusted to 8 After ~9, it flows into the sedimentation tank to remove large particles and sediment in the wastewater, and then flows into the coagulation tank, adding coagulants such as ferric chloride to remove some high-level organic substances, and remove a small amount of fine particles that may exist in the wastewater. Suspended solids and colloidal substances are intercepted and enter the concentrated water collection tank; then PAM (polyacrylamide) is added from the flow into the flocculation tank, and the mud and water are separated from the flow into the sedimentation tank. Front end for reprocessing. The above pretreatment supernatant enters UF after sand carbon filtration to separate SS, colloid, particulate matter and other pollutants in the wastewater; the water produced by the UF membrane system enters the seawater desalination membrane Ro system, and the concentrated water enters the evaporation treatment pretreatment water tank. The liquid is self-suctioned by the evaporation system and enters the preheater of the three-effect evaporator. After being evaporated by the three-effect evaporator, the concentrated liquid enters the separator of the three-effect evaporator. After passing through the separator, the condensed water is pumped to the sump by the condensate pump and collected. The water pump is lifted to the activated carbon filter for coarse filtration, and the large particles and silt in the wastewater are removed and then enters the MCR's carbon filter product water collection tank; the cleaning wastewater that has been pretreated above enters the cathodic resin (TP-207 ) system, carry out resin exchange to Cu, Ge and other heavy metal pollutants in waste water; then enter the anion resin (MP-68-P2), carry out resin exchange to heavy metal pollutants such as Ni in waste water; use 35wt% respectively after resin saturation hydrochloric acid and 25wt% NaOH to regenerate the resin to ensure its exchange efficiency. In order to strictly ensure the water quality of the workshop is good, heavy metals and part of COD in the wastewater are removed (conductivity ≤ 50μs/cm, Cod ≤ 30mg/L), and then enter the reuse water system. The Ro membrane is permeated, and the final product water is directly returned to the electroplating workshop for normal production; the Ro concentrated water enters the high-concentration wastewater treatment system for retreatment. A small amount of evaporated waste liquid (about 5%) is discharged into the high-concentration waste liquid tank and entrusted to a qualified treatment company for further processing.

1.3 Pretreatment + UF + seawater desalination membrane (recorded as Scheme 3, as shown in Figure 1)

Pretreatment: After the high-concentration wastewater from the workshop is adjusted to a pH value of 3 to 4, it enters the reduction tank, and a reducing agent (sodium bisulfite) is added to reduce the oxidized substances in the wastewater. After that, the wastewater flows into the pH adjustment tank, and the pH is adjusted to 8 After ~9, it flows into the sedimentation tank to remove large particles and sediment in the wastewater, and then flows into the MCR system to intercept a small amount of fine suspended solids and colloidal substances that may exist in the wastewater and then enter the concentrated water collection tank; after the above pre-treatment Treated wastewater enters the STUF membrane system to separate SS, colloid, particulate matter and other pollutants in the wastewater; the water produced by the STUF membrane system enters the buffer water tank of the STRO system, and the high-pressure pump of the buffer water tank passes through the security filter and then enters the STRO system for pre-concentration of raw water , separate and dissolve inorganic salts and heavy metal pollutants, the produced water enters the three-stage Ro primary production water tank, and the concentrated water enters the buffer water tank of the DTRO system. The water enters the three-stage Ro primary product water tank, and the concentrated water enters the evaporation treatment pretreatment water tank. The concentrated liquid is vacuum self-suctioned by the evaporation system and enters the three-effect evaporator preheater. The concentrated liquid is evaporated by the three-effect evaporator and then enters the three-effect evaporator for separation. After passing through the separator, the condensed water is pumped to the sump by the condensed water pump and collected, then lifted to the activated carbon filter by the water pump for coarse filtration, and the large particles and sediment in the wastewater are removed, and then enters the MCR carbon filter product water collection tank; After the above pretreatment, the cleaning wastewater enters the cationic resin (TP-207) system through the bag filter, and performs resin exchange on heavy metal pollutants such as Cu and Ge in the wastewater; then enters the cationic resin (MP-68-P2) to treat The heavy metal pollutants such as Ni in the waste water are exchanged with the resin; after the resin is saturated, the resin is regenerated with 35wt% hydrochloric acid and 25wt% NaOH to ensure the exchange efficiency. In order to strictly ensure the water quality of the workshop is good, heavy metals and part of COD in the wastewater are removed (conductivity ≤ 50μs/cm, Cod ≤ 30mg/L), and then enter the reuse water system. The Ro membrane is permeated, and the final product water is directly returned to the electroplating workshop for normal production; the Ro concentrated water enters the high-concentration wastewater treatment system for retreatment. A small amount of evaporated waste liquid (about 1%) is discharged into the high-concentration waste liquid tank and entrusted to a qualified treatment company for further processing.

As shown in Table 2, it shows the treatment results of three different treatment methods for high-concentration wastewater.

Table 2 Treatment results of three different treatment methods for high concentration wastewater

The water quality after the treatment of the high-concentration wastewater (three treatment methods) was tested, and the results are shown in Table 3.

Table 3 Water quality after treatment

From Table 2 and Table 3, it can be seen that the treatment method of Li+UF+seawater desalination membrane is used to treat high-concentration wastewater, which produces less waste liquid, large treatment capacity, and high wastewater reuse rate.

As can be seen from the above, the treatment method provided by the present invention classifies the electroplating wastewater, carries out targeted treatment of wastewater with different pollution levels, and selects a full physical separation process technology that only introduces a small amount of foreign agents. After the wastewater is treated, it can reach the industrial reuse water standard. , low conductivity, not easy to block the membrane, the wastewater reuse rate is over 99%, only about 1% of the waste liquid is produced after treatment, and zero discharge of wastewater can be realized; after treatment, the recycled water quality is directly used in the electroplating workshop for normal production.

Those skilled in the art will appreciate that the embodiments herein are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (9)

1. a kind of zero emission of high-concentration wastewater processing method, which comprises the steps of:

S1: after the pH for adjusting hc effluent is 3~4, after reducing agent is added, readjustment pH is 8~10, coarse filtration, again using MCR technology It after secondary filtering, is filtered using STUF membranous system technology, concentration, then evaporates, must be discharged after separation；

S2: water outlet is filtered after coarse filtration using MCR technology again, after then carrying out ion exchange using negative resin and positive resin, Successively through UF film and the reverse osmosis Ro film process of three-level after carbon filtration, Ro produce water be can reuse water quality, Ro concentrated water is as highly concentrated useless Water repeats S1~S2 step and is handled.

2. zero emission of high-concentration wastewater processing method according to claim 1, which is characterized in that the pH of hc effluent described in S1 For 5~6, COD >=3000mg/L, conductivity >=10000 μ s/cm.

3. zero emission of high-concentration wastewater processing method according to claim 1, which is characterized in that the skill of STUF membranous system described in S1 Art includes STRO pre-concentration technology and DTRO secondary concentration technology.

4. processing method according to claim 1, which is characterized in that the boiled off liquor evaporated in S1 is not higher than 1%.

5. processing method according to claim 1, which is characterized in that carry out coarse filtration using active carbon in S2.

6. processing method according to claim 1, which is characterized in that negative resin is TP-207, positive resin MP-68- in S2 P2；The number of the ion exchange is one or many.

7. processing method according to claim 1, which is characterized in that further include being regenerated to negative resin and positive resin in S2 The step of processing.

8. processing method according to claim 7, which is characterized in that carry out regeneration treatment to negative resin using hydrochloric acid in S2； Regeneration treatment is carried out to positive resin using sodium hydroxide solution.

9. processing method according to claim 1, which is characterized in that the boiled off liquor evaporated in S2 is not higher than 1%.