CN113185040A - Low-cost desulfurization wastewater softening treatment process for softening by carbon dioxide auxiliary reinforcement - Google Patents
Low-cost desulfurization wastewater softening treatment process for softening by carbon dioxide auxiliary reinforcement Download PDFInfo
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- CN113185040A CN113185040A CN202110337458.6A CN202110337458A CN113185040A CN 113185040 A CN113185040 A CN 113185040A CN 202110337458 A CN202110337458 A CN 202110337458A CN 113185040 A CN113185040 A CN 113185040A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/101—Sulfur compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
Abstract
The invention relates to a low-cost desulfurization wastewater softening treatment process for carbon dioxide-assisted reinforced softening, which solves the problems that the prior art can not meet the current environmental protection requirement or has high investment and operation cost, the treated product can not realize resource utilization and the like. The invention comprises an integrated neutralization-precipitation treatment system, a strengthening softening system, a sludge concentration and dehydration system and a softened sludge collection and reuse system. The invention provides a new process for the low-cost softening treatment of the desulfurization wastewater through the coupling synergistic effect of multiple systems, has reasonable design, meets the national environmental protection requirement, has low operation cost, and can recycle the treated product.
Description
Technical Field
The invention relates to a treatment process, in particular to a low-cost desulfurization wastewater softening treatment process for carbon dioxide assisted strengthening softening, and belongs to the technical field of wastewater treatment.
Background
At present, the specific processes for softening desulfurization wastewater of coal-fired power plants mainly comprise the following steps:
firstly, desulfurized wastewater → chemical adding softening treatment → tubular microfiltration treatment. For example, in the patent No. 201610950009.8, the desulfurization wastewater is treated by lime softening, then treated water is treated by a tubular microfiltration membrane, and the treated water is treated by two softening agents and then enters a tubular microfiltration membrane system for treatment. The process needs to add three medicaments to realize the softening treatment of the desulfurization wastewater, and adopts a tubular microfiltration membrane, so that the equipment investment is large and the operation cost is high.
② adopting the process of desulfurization waste water → dosing and magnesium removal → softening by a seed crystal method. For example, in Chinese patent with application number CN2017/072023, calcium ions and heavy metal ions in the desulfurization wastewater are removed by adding seed crystals, and magnesium ions in the desulfurization wastewater are removed by adding the seed crystals, so that the desulfurization wastewater is softened. The device and the method can soften the desulfurization wastewater, but because the calcium ions in the desulfurization wastewater are difficult to effectively remove by only depending on the seed crystal, the concentration of the calcium ions in the treated water is still high, the treated water still has a high scaling tendency, and the hardness requirement of a subsequent membrane system on the inlet water is difficult to meet.
High-salinity wastewater → lime neutralization treatment → polyaluminium chloride coagulation treatment → flue gas carbon dioxide circulation softening treatment → ceramic membrane turbidity removal treatment → reverse osmosis concentration treatment → bypass flue evaporation treatment. For example, the Chinese patent with the application number of 201710240968.5 carries out lime neutralization, dosing coagulation, carbon dioxide circular softening, ultrafiltration, reverse osmosis and bypass flue evaporation on the desulfurization wastewater, thereby realizing zero emission treatment of the desulfurization wastewater. The process flow is long, the system is relatively complex, sludge generated by system operation needs to be considered for treatment, and the system operation cost is high.
Therefore, in order to overcome the defects of the various treatment processes, the market urgently needs to develop a coal-fired power plant desulfurization wastewater softening treatment process and system with low energy consumption and low investment and operation cost.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a low-cost desulfurization wastewater softening treatment process with carbon dioxide-assisted strengthening softening, which has the advantages of simple and reasonable treatment process, low energy consumption and low investment and operation cost.
The technical scheme adopted by the invention for solving the problems is as follows: the low-cost desulfurization wastewater softening treatment process with carbon dioxide assisted strengthening and softening comprises an integrated neutralization-precipitation device, a sludge concentration tank, a sludge dewatering device, a strengthening and softening device, a softened sludge collecting tank, a limestone-gypsum wet desulfurization system, a subsequent treatment device or an ash system and a desulfurization wastewater buffer tank, wherein the integrated neutralization-precipitation device is connected with the desulfurization wastewater buffer tank, the integrated neutralization-precipitation device is connected with the strengthening and softening device, and the strengthening and softening device is connected with the subsequent treatment device or the ash system; the sludge concentration box is connected with the integrated neutralization-precipitation device, and the sludge dewatering device is connected with the sludge concentration box; the softened sludge collecting tank is connected with the strengthening softening device, and the limestone-gypsum wet desulphurization system is connected with the softened sludge collecting tank, and is characterized in that: the method comprises the following specific steps:
s1: the desulfurization wastewater in the desulfurization wastewater buffer tank is sequentially treated by the integrated neutralization-precipitation device and the intensified softening device, and the treated desulfurization wastewater is introduced into a subsequent treatment device or an ash system for recycling, so that the concentration of calcium and magnesium ions in the desulfurization wastewater treated by the process can be reduced to be below 20mg/L, and the water inlet hardness requirement of a membrane system such as ultrafiltration and reverse osmosis is met;
s2: in the integrated neutralization-precipitation device, under the action of NaOH and coagulant, magnesium ions form Mg (OH)2The flocs are precipitated together with other suspended matters in the desulfurization wastewaterPrecipitating, wherein the precipitate enters a sludge concentration tank through an inclined plate clarifier in a precipitation device;
s3: sludge in the sludge concentration tank enters a sludge dewatering device through a sludge delivery pump, sludge generated by the sludge dewatering device is transported outwards, and generated supernatant is returned to the integrated neutralization-precipitation device for treatment;
s4: adding crystal seeds into the strengthening softening device, blowing carbon dioxide (or air containing carbon dioxide, flue gas and the like), enabling the desulfurization wastewater to react with calcium and magnesium ions in the wastewater in the strengthening softening device to generate calcium carbonate and magnesium carbonate precipitates to be attached to the crystal seeds so as to enable the crystal seeds to grow gradually, enabling the wastewater to circularly flow in the strengthening softening system under the action of a circulating pump, enabling the crystal seeds to be in a suspension rolling state, overcoming turbulent motion of water flow and precipitating the grown crystal seeds under the action of self gravity to form granular softened sludge, and discharging the granular softened sludge into a softened sludge collection tank;
s5: the softened sludge is granular, the main components of the softened sludge are calcium carbonate and a small part of magnesium carbonate, and the softened sludge is periodically cleaned and transported to a limestone-gypsum wet desulphurization system for pulping and recycling.
Compared with the prior art, the invention has the following advantages and effects: (1) the treatment process utilizes the principle that carbon dioxide reacts with calcium ions to generate calcium carbonate crystals, and takes natural mineral powder particles as crystal seeds, so that the aim of assisting and strengthening calcium ion crystallization in wastewater by carbon dioxide is fulfilled, low-cost softening treatment of desulfurization wastewater is realized, and softened sludge particles are reused in a wet desulfurization system, so that not only is the resource treatment of sludge realized, but also part of a desulfurizing agent can be saved, and the treatment process has good economic benefits and outstanding environmental protection benefits; (2) the treatment process can realize low-cost softening treatment of the desulfurization wastewater and resource utilization of softened sludge, remarkably reduce the concentration of calcium and magnesium ions in treated effluent, reduce the calcium and magnesium ions in the treated effluent to below 20mg/L, and meet the requirements of membrane systems such as ultrafiltration and reverse osmosis on the hardness of inlet water.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
In the figure: the system comprises an integrated neutralization-precipitation device 1, a sludge concentration box 2, a sludge dewatering device 3, a strengthening softening device 4, a softened sludge collecting tank 5, a limestone-gypsum wet desulphurization system 6, a subsequent treatment device or ash system 7 and a desulphurization wastewater buffer tank 8.
Detailed Description
The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.
Examples are given.
Referring to fig. 1, a low-cost desulfurization wastewater softening treatment process with carbon dioxide-assisted strengthening softening comprises a desulfurization wastewater buffer tank 8, an integrated neutralization-precipitation device 1, a sludge concentration tank 2, a sludge dewatering device 3, a strengthening softening device 4, a softened sludge collecting tank 5, a limestone-gypsum wet desulfurization system 6, and a subsequent treatment device or ash system 7; the integrated neutralization-precipitation device 1 is connected with a desulfurization wastewater buffer tank 8, the integrated neutralization-precipitation device 1 is connected with an intensified softening device 4, and the intensified softening device 4 is connected with a subsequent treatment device or an ash system 7; the sludge concentration box 2 is connected with the integrated neutralization-precipitation device 1, and the sludge dewatering device 3 is connected with the sludge concentration box 2; the softened sludge collecting tank 5 is connected with the strengthening softening device 4, and the limestone-gypsum wet desulphurization system 6 is connected with the softened sludge collecting tank 5.
The water quality and the water quantity of the desulfurization wastewater generated by a certain thermal power generating unit are as follows: 58000 mu s/cm of conductivity, TDS46000mg/L of conductivity, 520mg/L of calcium ion concentration, 2360mg/L of magnesium ion concentration and 15-20 m of water volume3H is used as the reference value. By adopting the process for treatment and through neutralization-precipitation integrated treatment, the removal rate of calcium ions reaches about 20 percent, the removal rate of magnesium ions reaches more than 90 percent, and the total hardness of treated effluent is obviously reduced. The integrally treated effluent enters a strengthening and softening treatment system, calcium ions, magnesium ions and carbonate ions react under the action of carbon dioxide to form carbonate crystal precipitates on the surfaces of crystal seeds, so that the calcium ions and the magnesium ions are further removed, and the concentration of the calcium ions and the magnesium ions in the treated effluent is lower than 20 mg/L. The desulfurization wastewater is softened by adopting the process, compared with the conventional lime/NaOH-Na2CO3The process reduces about 50% of the treatment cost per ton of water, and the softened sludge can be reused in a wet desulphurization system as a desulfurizer, thereby not only realizing the resource utilization of the sludge, but also saving the usage amount of the desulfurizer and having better economic benefit and environmental protection benefit.
The low-cost desulfurization wastewater softening treatment process with carbon dioxide assisted and strengthened softening comprises the following steps:
s1: the desulfurization wastewater in the desulfurization wastewater buffer tank 8 is sequentially treated by the integrated neutralization-precipitation device 1 and the strengthening softening device 4, and the treated desulfurization wastewater is introduced into a subsequent treatment device or an ash system 7 for recycling, so that the concentration of calcium and magnesium ions in the desulfurization wastewater treated by the process can be reduced to be below 20mg/L, and the water inlet hardness requirements of membrane systems such as ultrafiltration and reverse osmosis are met.
S2: in the integrated neutralization-precipitation device 1, under the action of NaOH and coagulant, magnesium ions form Mg (OH)2The floc and other suspended matters in the desulfurization wastewater form sediment, and the sediment enters the sludge concentration tank 2 through an inclined plate clarifier in the sediment device.
S3: the sludge in the sludge concentration box 2 enters a sludge dewatering device 3 through a sludge delivery pump, the sludge generated by the sludge dewatering device 3 is transported out, and the generated supernatant is returned to the integrated neutralization-precipitation device 1 for treatment.
S4: adding crystal seeds into the strengthening and softening device 4, blowing carbon dioxide (or air containing carbon dioxide, flue gas and the like), reacting the carbon dioxide with calcium and magnesium ions in the wastewater in the strengthening and softening device 4 to generate calcium carbonate and magnesium carbonate precipitates to be attached to the crystal seeds, so that the crystal seeds grow gradually, enabling the wastewater to circularly flow in the strengthening and softening system under the action of a circulating pump, enabling the crystal seeds to be in a suspension rolling state, overcoming turbulent fluctuation precipitation of water flow of the grown crystal seeds under the action of self gravity to form granular softened sludge, and discharging the granular softened sludge into the softened sludge collecting tank 5.
S5: the softened sludge is granular, the main components of the softened sludge are calcium carbonate and a small part of magnesium carbonate, and the softened sludge is periodically cleaned and conveyed to a limestone-gypsum wet desulphurization system 6 for pulping and recycling.
And will be apparent to those skilled in the art from the foregoing description.
In addition, it should be noted that the specific embodiments described in the present specification may be different in the components, the shapes of the components, the names of the components, and the like, and the above description is only an illustration of the structure of the present invention. Equivalent or simple changes in the structure, characteristics and principles of the invention are included in the protection scope of the patent. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
Claims (1)
1. A low-cost desulfurization wastewater softening treatment process with carbon dioxide assisted strengthening and softening comprises an integrated neutralization-precipitation device (1), a sludge concentration tank (2), a sludge dewatering device (3), a strengthening and softening device (4), a softened sludge collecting tank (5), a limestone-gypsum wet desulphurization system (6), a subsequent treatment device or ash system (7) and a desulfurization wastewater buffer tank (8), wherein the integrated neutralization-precipitation device (1) is connected with the desulfurization wastewater buffer tank (8), the integrated neutralization-precipitation device (1) is connected with the strengthening and softening device (4), and the strengthening and softening device (4) is connected with the subsequent treatment device or ash system (7); the sludge concentration box (2) is connected with the integrated neutralization-precipitation device (1), and the sludge dewatering device (3) is connected with the sludge concentration box (2); softened sludge collecting pit (5) are connected with intensive softening installation (4), and limestone-gypsum wet flue gas desulfurization system (6) are connected with softened sludge collecting pit (5), its characterized in that: the method comprises the following specific steps:
s1: the desulfurization wastewater in the desulfurization wastewater buffer tank (8) is treated by sequentially passing through the integrated neutralization-precipitation device (1) and the strengthening softening device (4), and the treated desulfurization wastewater is introduced into a subsequent treatment device or an ash system (7) for recycling;
s2: in an integrated neutralization-precipitation device (1), under the action of NaOH and a coagulant, magnesium ions form Mg (OH)2The floc and other suspended matters in the desulfurization wastewater form precipitate together, and the precipitate enters a sludge concentration tank (2) through an inclined plate clarifier in a precipitation device;
s3: sludge in the sludge concentration box (2) enters a sludge dewatering device (3) through a sludge delivery pump, sludge generated by the sludge dewatering device (3) is transported outwards, and generated supernatant returns to the integrated neutralization-precipitation device (1) for treatment;
s4: adding crystal seeds into the strengthening and softening device (4) and blowing carbon dioxide, reacting the desulfurization wastewater with calcium and magnesium ions in the wastewater to generate calcium carbonate and magnesium carbonate precipitates to be attached to the crystal seeds in the strengthening and softening device (4), so that the crystal seeds grow gradually, enabling the wastewater to circularly flow in the strengthening and softening system under the action of a circulating pump, enabling the crystal seeds to be in a suspension rolling state, overcoming turbulent fluctuation precipitation of water flow to form granular softened sludge under the action of self gravity of the grown crystal seeds, and discharging the granular softened sludge into a softened sludge collecting tank (5);
s5: the softened sludge is granular, the main components of the softened sludge are calcium carbonate and a small part of magnesium carbonate, and the softened sludge is periodically cleaned and conveyed to a limestone-gypsum wet desulphurization system (6) for pulping and recycling.
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Citations (3)
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|---|---|---|---|---|
| CN107244773A (en) * | 2017-05-25 | 2017-10-13 | 武汉尚源新能环境有限公司 | The technique of zero discharge and equipment of desulfurization wastewater Treatment and recovery |
| CN206751583U (en) * | 2017-05-27 | 2017-12-15 | 杭州匠容道环境科技有限公司 | Desulfurization wastewater Zero discharging system based on ion selectivity electrodialytic technique |
| CN108467135A (en) * | 2018-04-20 | 2018-08-31 | 西安建筑科技大学 | A kind of granulating fluidized bed water treatment system of full-automatic chemical crystallisation cycle |
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- 2021-03-30 CN CN202110337458.6A patent/CN113185040A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107244773A (en) * | 2017-05-25 | 2017-10-13 | 武汉尚源新能环境有限公司 | The technique of zero discharge and equipment of desulfurization wastewater Treatment and recovery |
| CN206751583U (en) * | 2017-05-27 | 2017-12-15 | 杭州匠容道环境科技有限公司 | Desulfurization wastewater Zero discharging system based on ion selectivity electrodialytic technique |
| CN108467135A (en) * | 2018-04-20 | 2018-08-31 | 西安建筑科技大学 | A kind of granulating fluidized bed water treatment system of full-automatic chemical crystallisation cycle |
Non-Patent Citations (1)
| Title |
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| 谢毅: "硫铁矿制酸废水处理及其回用新技术的研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑》 * |
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