CN105712559B - A kind of desulfurization wastewater film processing system and technique - Google Patents

Abstract

The invention belongs to desulfurization wastewater processing technology fields, a kind of desulfurization wastewater film processing system and technique are specifically provided, processing system includes passing through the sequentially connected former pond of pipeline, preliminary sedimentation tank, the first reaction tank, intermediate water tank, the second reaction tank, thickener, TMF device, TMF water producing tank, DTRO device, evaporator and drying device；The TMF device is connect by return line with thickener, and the concentrated water outlet of the DTRO device is connect with evaporator inlet.Desulfurization wastewater film processing system provided by the invention, structure is simple, area occupied is small, it is at low cost, used membrane treatment process, the effect for handling desulfurization wastewater is preferable, the heavy metal and suspended matter in waste water can be completely removed, producing water ratio is high and production water meets discharge standard, has feasibility and adaptability in terms of desulfurization wastewater zero discharge treatment.

Description

A desulfurization wastewater membrane treatment system and process

technical field

The invention belongs to the technical field of desulfurization wastewater treatment, and in particular relates to a desulfurization wastewater membrane treatment system and process.

Background technique

At present, the mainstream process of flue gas desulfurization in thermal power plants is limestone-gypsum wet flue gas desulfurization, which is mature and adaptable. During desulfurization by wet desulfurization process, the slurry in the desulfurization absorption tower is recycled repeatedly, and the soluble salt slurry in the tower is continuously concentrated. In order to ensure the desulfurization performance and maintain the balance of chloride ions in the system, it is necessary to continuously replenish and update the slurry. During this process, the slurry containing Wastewater with a large amount of heavy metal ions, the discharged wastewater is desulfurization wastewater.

The types of metal ions in desulfurization wastewater include conventional heavy metals (Cd, Cu, Cr, Ni, Pb, Zn, etc.), as well as some other non-heavy metal ions, such as As, Ba, Mo, Fe, Al, Sn, Ra, etc., while There are also features such as high salt content and high suspended solids. The common feature of these pollutants is that they can form precipitates after adding some chemicals. The traditional desulfurization wastewater treatment method adopts the chemical precipitation method. This treatment method needs to set up a sedimentation tank. Considering that the sedimentation water cannot completely remove the suspended solids SS and heavy metal suspended solids in the water quality, and after the sedimentation, a quartz sand filter, ultrafiltration, etc. are required. The precipitated water is reused after advanced treatment, which causes the waste water treatment station to increase the floor area and equipment investment in order to place a large number of equipment. Moreover, it is difficult to meet the standard discharge of desulfurization wastewater by ordinary methods, so it is particularly important to propose new treatment methods for desulfurization wastewater treatment.

Contents of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned prior art, and provide a desulfurization wastewater membrane treatment system and process, the wastewater treatment effect is good, the treated water reaches the discharge standard, and the membrane treatment system has a small footprint and low cost .

For this reason, the present invention provides a membrane treatment system for desulfurization wastewater, comprising a raw water tank, a pre-sedimentation tank, a first reaction tank, an intermediate water tank, a second reaction tank, a concentration tank, a TMF device, and a TMF production tank sequentially connected by pipelines. A water tank, a DTRO device, an evaporator and a drying device; the TMF device is connected to the concentration tank through a return line, and the concentrated water outlet of the DTRO device is connected to the evaporator inlet.

The desulfurization wastewater membrane treatment system provided by the present invention firstly performs preliminary softening pretreatment on the wastewater, preliminarily removes calcium, magnesium heavy metal ions and suspended solids in the wastewater, and then uses a TMF (tubular microfiltration membrane) device for cross-flow filtration treatment, The TMF device intercepts macromolecular suspended matter and reduces the hardness of the wastewater. The permeate from the TMF device enters the DTRO (high-pressure reverse osmosis membrane) device for concentration treatment to remove COD, bacteria, ammonia nitrogen and other pollutants in the wastewater. The concentrated concentrated water is sent to the evaporator for evaporation treatment, the solid crystals are dried and packaged, and the concentrated product water meets the discharge standard. The membrane treatment system has good wastewater treatment effect, can completely remove suspended solids SS and heavy metal suspended solids in the water quality, and the produced water meets the standard discharge standards, with small occupied area and low investment.

Further, the thickening tank is connected with a plate and frame filter press through pipelines. The plate and frame filter press dehydrates the sludge generated in the thickening tank, and the dehydrated sludge is treated as general solid waste.

As preferably, a first lift pump is provided on the pipeline between the raw water tank and the pre-sedimentation tank, a second lift pump is provided on the pipeline between the first reaction tank and the intermediate water tank, and the TMF water production tank and DTRO A third lift pump is provided on the pipeline between the devices.

Preferably, a circulation pump is provided on the pipeline between the concentration tank and the TMF device. Driven by the circulating pump, the TMF device has large inflow flow, high flow velocity and strong carrying capacity.

Furthermore, automatic stirring devices are respectively installed in the first reaction pool and the second reaction pool. The automatic stirring device fully stirs the waste liquid in the first reaction tank and the second reaction tank, the homogeneous waste liquid after stirring reacts more fully, the treatment effect is better, and the sedimentation rate is high.

As an improvement, the first reaction pool and the second reaction pool are respectively equipped with pH monitors. The accuracy of the pH value directly affects the wastewater treatment effect. If the pH value deviates from the control range, it will lead to incomplete precipitation of heavy metals in the wastewater and cannot effectively remove heavy metal ions in the wastewater. The pH monitor can monitor the pH in the reaction tank in real time and strictly control it. pH value.

The present invention also provides a desulfurization wastewater membrane treatment process, comprising the following steps:

Step a: Transport the collected desulfurization wastewater to the raw water tank. When the liquid level in the raw water tank reaches the set height, lift the desulfurization wastewater into the pre-sedimentation tank through the first lift pump. In the pre-sedimentation tank, the suspension in the desulfurization wastewater Pre-precipitation of matter and large particles;

Step b: Transport the pre-sedimentation liquid in the upper part of the pre-sedimentation tank to the first reaction tank, add lime to the first reaction tank for preliminary softening treatment, and form calcium sulfate and magnesium hydroxide precipitates, and at the same time, magnesium hydroxide carries silica Co-precipitation is formed; the first reaction liquid after preliminary softening is lifted to the intermediate water tank by the second lift pump;

Step c: the first reaction liquid in the intermediate water tank flows into the second reaction pool, sodium hydroxide is added to the second reaction pool, the pH of the first reaction liquid is finely adjusted, and the pH is controlled between 10-12, Magnesium hydroxide is completely precipitated, and sodium carbonate solution is added in the second reaction tank simultaneously, and sodium carbonate solution reacts with calcium ions remaining in the first reaction solution to form calcium carbonate precipitation;

Step d: The second reaction solution obtained after the reaction in the second reaction tank enters the concentration tank, the second reaction solution is concentrated and precipitated in the concentration tank, and the concentrated solution is sent to the TMF device through the circulation pump, and the TMF device is in the circulation pump The concentrated solution is cross-flow filtered under the impetus of the pump, and the filtered product water circulates between the TMF device and the concentration tank. The product water enters the TMF product water tank;

Step e: The TMF product water in the TMF product water tank is lifted to the DTRO device by the third lift pump, and the DTRO device performs high-power concentration treatment on the TMF product water, and the concentrated concentrated water is sent to the evaporator for evaporation and crystallization treatment, and the obtained solid The crystalline salt is dried and packaged, and the concentrated product water is collected and recycled.

Further, the thickening tank in the step d is connected to the plate-and-frame filter press through pipelines, and the sludge obtained after concentration in the thickening tank is transported to the plate-and-frame filter press for sludge pressure filtration treatment. The sludge will be processed for subsequent sludge solid waste disposal.

Furthermore, automatic stirring devices are respectively installed in the first reaction pool and the second reaction pool.

As a further improvement, the first reaction pool and the second reaction pool are respectively equipped with pH monitors.

Beneficial effects of the present invention: the desulfurization wastewater membrane treatment system provided by the present invention has a simple structure, a small occupied area, and low cost. The membrane treatment process adopted has a better effect in treating desulfurization wastewater and can completely remove heavy metals in wastewater As well as suspended solids, the water production rate is high and the produced water meets the discharge standards, which is feasible and adaptable in the zero discharge treatment of desulfurization wastewater.

Description of drawings

Figure 1 is a schematic diagram of the process flow of the desulfurization wastewater membrane treatment system provided by the present invention.

Explanation of reference signs: 1. Raw water tank; 2. Pre-sedimentation tank; 3. First reaction tank; 4. Intermediate water tank; 5. Second reaction tank; 6. Concentration tank; 7. TMF device; 8. TMF water production tank ;9, DTRO device; 10, evaporator; 11, drying device; 12, plate and frame filter press; 13, the first lifting pump; 14, the second lifting pump; 15, circulation pump; 16, return pipeline; 17 , The third lift pump.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

A desulfurization wastewater membrane treatment system as shown in Figure 1 includes a raw water tank 1, a pre-sedimentation tank 2, a first reaction tank 3, an intermediate water tank 4, a second reaction tank 5, a concentration tank 6, TMF device 7, TMF produced water tank 8, DTRO device 9, evaporator 10 and drying device 11; The TMF device 7 is connected with the concentration tank 6 through a return line 16, and the concentrated water outlet of the DTRO device 9 is connected to the evaporator 10 Ingress connection. The pipeline between the raw water tank 1 and the pre-sedimentation tank 2 is provided with a first lift pump 13, the pipeline between the first reaction tank 3 and the intermediate water tank 4 is provided with a second lift pump 14, and the TMF A third lift pump 17 is provided on the pipeline between the produced water tank 8 and the DTRO device 9 . A circulation pump 15 is arranged on the pipeline between the concentration tank 6 and the TMF device 7 , and the TMF device 7 is driven by the circulation pump 15 with a large inflow flow rate, a high flow rate and a strong carrying capacity. The concentration tank 6 is connected with a plate and frame filter press 12 through a pipeline. The plate and frame filter press 12 dehydrates the sludge generated in the thickening tank 6, and the dehydrated sludge is treated as general solid waste.

The first reaction pool 3 and the second reaction pool 5 are respectively equipped with automatic stirring devices. The automatic stirring device fully stirs the waste liquid in the first reaction pool 3 and the second reaction pool 5, and the stirred homogeneous waste liquid reacts more fully, with better treatment effect and high sedimentation rate.

In addition, the first reaction pool 3 and the second reaction pool 5 are respectively equipped with pH monitors. The accuracy of the pH value directly affects the wastewater treatment effect. If the pH value deviates from the control range, it will lead to incomplete precipitation of heavy metals in the wastewater and cannot effectively remove heavy metal ions in the wastewater. The pH monitor can monitor the pH in the reaction tank in real time and strictly control it. pH value.

The desulfurization wastewater membrane treatment system provided in this example firstly performs preliminary softening treatment on the wastewater, initially removes calcium, magnesium heavy metal ions and suspended solids in the wastewater, and then uses a TMF device for cross-flow filtration treatment, and the TMF device suspends macromolecules The interception of waste water reduces the hardness of wastewater. The permeate from the TMF device enters the DTRO device for concentration treatment to remove COD, bacteria, ammonia nitrogen and other pollutants in the wastewater, and the concentrated concentrated water is sent to the evaporator for evaporation treatment. , the solid crystals are dried and packaged, and the concentrated product water meets the discharge standard. The membrane treatment system has good wastewater treatment effect, can completely remove suspended solids SS and heavy metal suspended solids in the water quality, and the produced water meets the standard discharge standards, with small occupied area and low investment.

Example 2:

On the basis of Example 1, we also provide a membrane treatment process for desulfurization wastewater, and describe the process in detail in conjunction with Figure 1, including the following steps:

Step a: Transport the collected desulfurization wastewater to the raw water pool 1. When the liquid level in the raw water pool 1 reaches the set height, lift the desulfurization wastewater into the pre-sedimentation tank 2 through the first lift pump 13, In 2, the suspended solids and large particles in the desulfurization wastewater are pre-precipitated;

Step b: transport the pre-sedimentation liquid in the upper part of the pre-settling tank 2 to the first reaction tank 3, add lime to the first reaction tank 3 for preliminary softening treatment, form calcium sulfate and magnesium hydroxide precipitates, and simultaneously Magnesium carries silicon dioxide to form co-precipitation; the first reaction liquid after preliminary softening is lifted to the intermediate water tank 4 by the second lift pump 14; the first reaction tank 3 is equipped with an automatic stirring device. The medicament and the waste water are completely mixed and reacted by stirring thoroughly.

Step c: the first reaction liquid in the intermediate water tank 4 flows into the second reaction pool 5, and sodium hydroxide is added in the second reaction pool 5 to fine-tune the pH of the first reaction liquid. A PH monitor is provided to control the PH between 10-12, preferably 11.5, and the magnesium hydroxide is completely precipitated. At the same time, a sodium carbonate solution is added in the second reaction tank 5, and the sodium carbonate solution and the first reaction solution remain The calcium ions react to form calcium carbonate precipitation; the second reaction pool 5 is provided with an automatic stirring device and a pH monitor. The medicament and the waste water are completely mixed and reacted by stirring thoroughly.

Step d: the second reaction solution obtained after the reaction in the second reaction tank 5 enters the concentration tank 6, the second reaction solution is concentrated and precipitated in the concentration tank 6, and the concentrated solution is sent to the TMF device 7 through the circulation pump 15 , the TMF device 7 carries out cross-flow filtration to the concentrate under the promotion of the circulation pump 15, a return line 16 is provided between the TMF device 7 and the concentration tank 6, and the filtered product water is between the TMF device 7 and the concentration tank 6 Circulation, the circulating product water is adjusted by adding hydrochloric acid for pH adjustment, and discharged after reaching the discharge standard, or the recycled product water enters the TMF product water tank 8; further, the concentration tank 6 passes through the pipeline and the plate and frame filter press 12 is connected, and the sludge obtained after concentration in the concentration tank 6 is transported to the plate and frame filter press 12 for sludge pressure filtration treatment, and the sludge after the pressure filtration treatment is subjected to subsequent sludge solid waste disposal.

TMF device 7 adopts cross-flow tubular filtration, which replaces the traditional sedimentation and clarification process, and achieves good effluent quality. The microporous membrane is used to separate the sediment in the wastewater, and the sediment particle size and specific gravity are not required to be large enough. Large enough so that it is a more efficient separation method when converting a substance from a dissolved state to an insoluble state.

After a period of stable operation, the analysis of the raw water and product water quality of the TMF unit is as follows,

It can be seen from the key hardness and other indicators that the calcium and magnesium hardness in the produced water of the TMF device can be controlled within 50mg/L, which fully meets the subsequent membrane concentration requirements. In addition, the alkalinity can be supplemented and reduced by increasing the dosage. hardness.

Step e: The TMF produced water in the TMF produced water tank 8 is lifted to the DTRO device 9 through the third lift pump 17, and the DTRO device 9 performs high-power concentration treatment on the TMF produced water, and the concentrated concentrated water is sent to the evaporator 10 for evaporation and crystallization treatment , the obtained solid crystalline salt is dried and packaged, and the concentrated product water is collected and recycled.

The DTRO device 9 is equipped with a single DTRO membrane (high-pressure reverse osmosis membrane), the membrane area is ^9.405m2 , the membrane flux is set between 5-30L/m2 ^. h, and the supporting equipment includes filters, high-pressure pumps, booster Pumps, high-pressure membrane casings. A high-pressure reverse osmosis membrane with a pressure rating of 120kg is selected, and the high-pressure pump is set with frequency conversion, and the pressure is adjustable. When the minimum pressure of the high-pressure pump is 90kg, the TDS of concentrated water measured at this time is 98600mg/L, and the maximum pressure of the high-pressure pump is 117kg. The water quality analysis of the DTRO unit is as follows,

Analysis Project DTRO concentrated water 1 DTRO concentrated water 2 Conductance (ms/cm) 114.4 124.4 TDS(mg/L) 111820 130580 Ca2+(mg/L) 37.81 42.65 Mg2+(mg/L) 6.59 5.12 Cl-(mg/L) 54118.1 60874.96 SO42-(mg/L) 1124.742 1262.104 F-(mg/L) ND ND NO3-N(mg/L) 718.98 780.76 Strontium (mg/L) 0.5 0.5 Sodium (mg/L) 37000 41000 Potassium (mg/L) 520 600

Stable operation for about 1 month, no obvious abnormality in the pressure difference of the membrane system, less pollution of the membrane system, TDS of DTRO produced water is within 500mg/L, and the produced water meets the discharge standard, and the concentrated water of DTRO directly enters the subsequent evaporation and crystallization system. A secondary reverse osmosis system can be installed to improve water quality to a higher standard.

The above examples are only illustrations of the present invention, and do not constitute a limitation to the protection scope of the present invention. All designs that are the same as or similar to the present invention fall within the protection scope of the present invention.

Claims (7)

1. a kind of desulfurization wastewater film processing system, which is characterized in that including passing through the sequentially connected former pond of pipeline (1), preliminary sedimentation Pond (2), the first reaction tank (3), intermediate water tank (4), the second reaction tank (5), thickener (6), TMF device (7), TMF water producing tank (8), DTRO device (9), evaporator (10) and drying device (11)；The TMF device (7) by return line (16) with it is dense The concentrated water outlet of contracting slot (6) connection, the DTRO device (9) is connect with evaporator (10) entrance；The film processing system processing The treatment process of desulfurization wastewater includes the following steps:

Step a: the desulfurization wastewater being collected into is transported in former pond (1), when former pond (1), interior liquid level reaches setting height When, desulfurization wastewater is promoted into preliminary sedimentation tank (2) by the first elevator pump (13), it is outstanding in desulfurization wastewater in preliminary sedimentation tank (2) Floating object and big particulate matter carry out preformed precipitate；

Step b: the preliminary sedimentation liquid on preliminary sedimentation tank (2) top is transported in the first reaction tank (3), is added into the first reaction tank (3) Lime carries out preliminarily softened processing, forms the sediment of calcium sulfate, magnesium hydroxide, while magnesium hydroxide carries silica and formed Co-precipitation；The first reaction solution after preliminarily softened is promoted by the second elevator pump (14) to intermediate water tank (4)；

Step c: the first reaction solution in intermediate water tank (4) adds from flowing into the second reaction tank (5) into the second reaction tank (5) Adding sodium hydroxide carries out accurate adjustment to the pH of the first reaction solution, and by pH control between 10-12, magnesium hydroxide is precipitated completely, Sodium carbonate liquor is added in the second reaction tank (5) simultaneously, sodium carbonate liquor is reacted with remaining calcium ion in the first reaction solution Form precipitation of calcium carbonate；

The second reaction solution obtained after reaction in the d: the second reaction tank of step (5) enters thickener (6), and the second reaction solution is dense Contracting slot (6) interior concentrating and precipitating, the concentrate after concentration are sent to TMF device (7) through circulating pump (15), and TMF device (7) is recycling It pumps and cross-flow filtration is carried out to concentrate under the promotion of (15), filtered production water follows between TMF device (7) and thickener (6) Ring, the production water after circulation are added hydrochloric acid and carry out pH adjustment, discharged after reaching qualified discharge standard, or the production water after circulation into Enter to TMF water producing tank (8)；

TMF in step e:TMF water producing tank (8) produces water and is promoted through third elevator pump (17) to DTRO device (9), DTRO device (9) water being produced to TMF and carries out high power concentration, the concentrated water after concentration is sent to evaporator (10) and is evaporated crystallization treatment, will The solid crystal salt arrived is dry to be packaged, and the production water after concentration is recycled after collecting.

2. a kind of desulfurization wastewater film processing system as described in claim 1, which is characterized in that the thickener (6) passes through pipe Road is connect with plate and frame filter press (12).

3. a kind of desulfurization wastewater film processing system as described in claim 1, which is characterized in that the former pond (1) and preliminary sedimentation Pipeline between pond (2) is equipped with the first elevator pump (13), the pipeline between first reaction tank (3) and intermediate water tank (4) It is equipped with the second elevator pump (14), the pipeline between the TMF water producing tank (8) and DTRO device (9) is equipped with third elevator pump (17).

4. a kind of desulfurization wastewater film processing system as described in claim 1, which is characterized in that the thickener (6) and TMF are filled The pipeline set between (7) is equipped with circulating pump (15).

5. a kind of desulfurization wastewater film processing system as described in claim 1, which is characterized in that first reaction tank (3) and Self- poking arrangement is respectively equipped in second reaction tank (5).

6. a kind of desulfurization wastewater film processing system as described in claim 1, which is characterized in that first reaction tank (3) and Second reaction tank (5) is each configured with pH monitor.

7. a kind of desulfurization wastewater film processing system as described in claim 1, which is characterized in that the thickener in the step d (6) it is connect by pipeline with plate and frame filter press (12), the sludge obtained after concentration in thickener (6) is transported to plate and frame filter press (12) sludge press filtration processing is carried out, filters pressing treated sludge is subjected to subsequent sludge solidification disposal of waste.