CN108249646B - Power plant desulfurization wastewater zero-emission treatment process and device capable of recycling resources - Google Patents
Power plant desulfurization wastewater zero-emission treatment process and device capable of recycling resources Download PDFInfo
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Abstract
The invention discloses a power plant desulfurization wastewater zero-emission treatment process capable of recycling resources, which sequentially comprises three-header pretreatment, dual-alkali hardness removal, tubular UF ultrafiltration, nanofiltration, reverse osmosis and acid-base recovery. The invention realizes the deep zero discharge treatment of the desulfurization wastewater of the power plant, fully utilizes the sodium chloride contained in the wastewater to directly prepare the available acid/alkali, and realizes the recycling of resources.
Description
Technical Field
The invention relates to the technical field of power plant desulfurization wastewater treatment, in particular to a power plant desulfurization wastewater zero-emission treatment process and device capable of recycling resources.
Background
The existing desulfurization wastewater treatment process of the power plant comprises the following steps:
the electric field desulfurization wastewater low-consumption zero-emission treatment method disclosed in patent 1 (201710410199. X) comprises the steps of pretreating wastewater, adding sodium hydroxide, sodium carbonate and sodium hypochlorite, removing bivalent and trivalent scaling ions in the desulfurization wastewater and inhibiting microorganism growth; then solid-liquid separation is carried out by using a tubular ultrafiltration membrane; concentrating the desulfurization wastewater by nanofiltration, and further removing bivalent and trivalent scaling ions in the desulfurization wastewater; then carrying out reverse osmosis process treatment on nanofiltration produced water; heating, evaporating and concentrating the high-concentration sodium chloride solution; and finally concentrating, crystallizing, dehydrating and drying the concentrated brine.
The scheme of the patent 1 has the defects that: heavy metal trapping agent is not added in the pretreatment stage, so that heavy metal ions which cannot be removed by hydroxide precipitation cannot be removed; sodium hypochlorite is added, if the addition amount is controlled improperly, the subsequent nanofiltration membrane and RO membrane are easily damaged; the purity of the sodium chloride solid obtained by evaporation is not high, the sodium chloride solid cannot be transported or sold outside, and the sodium chloride solid is applied very little in the field, so that the value is not high; the pretreatment requires additional addition of acid and base to consume the medicament.
Patent 2 (201611024049.6) discloses a desulfurization wastewater zero-emission treatment method, which comprises the following steps:
electric flocculation: the desulfurization wastewater produced by the production is subjected to electric flocculation to remove part of organic matters, ss and heavy metals;
double-alkali chemical softening: organic matters produced by electric flocculation enter double-alkali chemical sedimentation;
tubular membrane ultrafiltration: the pH value of the settled water body is regulated by acid produced by the bipolar membrane, so that the water body is kept slightly alkaline;
nanofiltration membrane: then removing bivalent salt in the water body through nanofiltration to realize salt separation;
ED concentration: purified brine enters a homogeneous ED for concentration, and concentrated salt after concentration and water-break separation are discharged;
preparing acid and alkali; the concentrated brine passes through a BPED bipolar membrane electrodialysis system to prepare acid and alkali, and the prepared acid and alkali are used for softening double alkali in the second step and other production applications.
The method of patent 2 has the following defects: the electric flocculation electrode is easy to passivate, high in energy consumption and fast in electrode consumption, so that the operation cost is increased; the desalination rate and recovery rate of ED concentration are low; ED cleaning maintenance is frequent and complex; after nanofiltration, the desulfurization wastewater of the power plant is still high in monovalent salt content, and ED energy consumption is high.
Patent 3 (201510529034.4) discloses a desulfurization wastewater zero-emission treatment process, which comprises the following steps:
firstly, adding a certain amount of liquid medicine into a neutralization regulating tank to enable a plurality of heavy metal ions to generate indissolvable hydroxide precipitates in an alkaline environment;
step two, after the reagent is added into the desulfurization wastewater, most heavy metal ions form indissoluble hydroxide when the pH value reaches 9.0 to 9.5, and meanwhile Ca2+ in the water can also react with part of F-in the wastewater to generate indissoluble CaF2 precipitate so as to achieve the effect of removing fluorine;
step three, flocculating and settling to enable colloid particles and suspended particles to be aggregated and aggregated, adding a flocculating agent to enable the liquid medicine to fully react, and settling for a certain time, wherein the upper part of a flocculating and settling tank is supernatant liquid, and the lower part of the flocculating and settling tank is concentrated liquid;
and fourthly, discharging solid waste and wastewater after the lower concentrated solution passes through a sludge concentration box and a plate-and-frame sludge press filter, and introducing the wastewater into a neutralization regulating tank through a pipeline for recycling and reprocessing. The supernatant liquid is passed through a full-automatic softening filter to effectively remove calcium ions in the wastewater, so as to protect a reverse osmosis device in subsequent treatment; meanwhile, the softener has the filtering function;
step five, automatically back flushing the ultrafilter in the operation process, so as to ensure that the ultrafilter is not polluted;
step six, the concentrated water is subjected to first-stage and second-stage RO reverse osmosis and a crystallization evaporator to prepare crystal salt, and the salt concentration in the wastewater is improved through reverse osmosis concentration, so that the energy consumption is saved in evaporation crystallization; and recycling purified water generated by reverse osmosis concentration.
The drawbacks of patent 3 are as follows: no nanofiltration membrane is used for separating salt, RO is directly used for concentration, so that the pressure of an RO system is higher, and the crystalline salt obtained by evaporating concentrated solution is impure. The purity of the sodium chloride solid obtained by evaporation is not high, the sodium chloride solid cannot be transported or sold outside, and the sodium chloride solid is applied very little in the field, so that the value is not high; the pretreatment requires additional addition of acid and base to consume the medicament.
Patent 4 (201610901996.2) discloses a power plant desulfurization wastewater zero discharge process, which comprises the following steps:
firstly, desulfurization wastewater of a power plant firstly enters a raw water tank, and is subjected to homogenization adjustment in the raw water tank, so that the water quality of the wastewater is kept relatively stable;
step two, the effluent of a raw water tank enters a first flocculation reaction tank, a flocculating agent and a high polymer are added into the first flocculation tank for flocculation precipitation, the wastewater flocculated by the first flocculation reaction tank enters a first sedimentation tank, the flocculate formed in the wastewater of the first sedimentation tank is reduced to the tank bottom to form sludge, the sludge is sent into a sludge storage tank and then is sent into a sludge concentration tank, the concentrated sludge enters a filter press for dehydration, a sludge cake is sent to a designated place for landfill, and filtrate is returned to the sludge concentration tank;
step three, enabling the supernatant fluid of the first precipitation tank to enter a UF ultrafiltration system to further remove jelly and high polymer organic matters in the wastewater;
step four, the effluent enters an NF sodium filtration system, and the concentrated water enters a second flocculation reaction tank;
fifthly, the effluent of the nanofiltration system enters an RO reverse osmosis system, and the concentrated water enters a second flocculation reaction tank;
step six, adding chemical agents mainly comprising NaOH, na2CO3 and Polymer into the second flocculation reaction tank, wherein the dosage is 1-5 ppm; the flocculated concentrated water enters a second sedimentation tank, sludge at the bottom of the sedimentation tank enters a sludge concentration tank, effluent enters a first decompression evaporator, na2SO4 is output by evaporation and is sent to a first centrifugal machine for solid-liquid separation to obtain Na2SO4 crystals, part of filtrate flows back to the evaporator, the rest of filtrate enters a dryer to form sludge cakes, the formed sludge cakes are sent to a designated place for landfill, steam containing pollutants generated in the drying process enters a washing tower, and washing water returns to a raw water tank;
and seventh, recycling water produced by the RO reverse osmosis system as reuse water, enabling the concentrated water to enter a second decompression evaporator, evaporating and separating NaCl, sending the NaCl to a second centrifugal machine for solid-liquid separation to obtain NaCl crystals, enabling part of filtrate to flow back to the evaporator, and enabling the rest of filtrate to enter a dryer to form sludge cakes, and filling the sludge cakes.
The drawbacks of patent 4 are as follows: adding flocculant and high molecular polymer in the pretreatment process, and polluting the subsequent ultrafiltration and nanofiltration system if the adding amount is not well controlled; because part of chemical agents are added before evaporation, the scaling of the heat exchanger of the evaporator is easy to cause, and the heat transfer efficiency of the evaporator is affected; the evaporated mud cake needs to be reprocessed, so that the resource utilization can not be realized; the pretreatment requires additional addition of acid and base to consume the medicament.
Disclosure of Invention
The invention mainly aims to provide a power plant desulfurization wastewater zero-emission treatment process capable of recycling resources, which is used for deeply treating desulfurization wastewater, realizing wastewater zero emission, and fully utilizing sodium chloride contained in wastewater to prepare recyclable acid/alkali;
the invention aims at providing a power plant desulfurization wastewater zero discharge treatment device capable of recycling resources, and realizing desulfurization wastewater flow treatment and resource recycling.
In order to achieve the above object, the solution of the present invention is:
the zero discharge treatment process of the desulfurization wastewater of the power plant capable of recycling resources comprises the following steps:
(1) Pretreatment of a three-header: pumping the wastewater into a neutralization tank, and adding Ca (OH) into the neutralization tank 2 The pH value of the wastewater is adjusted to 7-9, then overflows into a reaction tank, organic sulfur is added into the reaction tank to precipitate heavy metal ions, the reaction tank overflows into a flocculation tank, a flocculating agent is added into the flocculation tank, and then the wastewater flows into a clarification tank to separate out precipitate to obtain clarified liquid;
(2) Double alkali method for removing hardness: reacting the clarified liquid with lime with the mass concentration of 1.8-2.3% in a reaction tank, then reacting with sodium carbonate with the mass concentration of 2.0-2.5% in a coagulating liquid state, then entering a concentrating water tank in the coagulating liquid state, periodically discharging sludge outside the concentrating water tank to a sludge concentrating tank, concentrating the sludge, and then entering a plate-and-frame filter press for filter pressing treatment to form mud cakes, thereby further removing bivalent and trivalent scaling ions in the desulfurization wastewater;
(3) Tubular UF ultrafiltration: the water produced by the concentration water tank enters a tubular UF membrane component through a lifting pump, the suspended matters after coagulation are filtered, ultrafiltration water produced is obtained through separation and clarification, and ultrafiltration concentrated water flows back to the concentration water tank;
(4) Nanofiltration: separating salt by a nanofiltration membrane component after ultrafiltration water production is returned to be acidic, intercepting divalent salt and TOC by the nanofiltration membrane, and penetrating sodium chloride to obtain water mainly containing monovalent sodium chloride salt, and treating the water by an RO membrane component (reverse osmosis membrane component), wherein concentrated water returns to the reaction tank in the step (2);
(5) Reverse osmosis: further concentrating the nanofiltration produced water by using an RO membrane assembly, and discharging or recycling the RO produced water;
(6) Acid and alkali recovery: and (3) passing the RO concentrated water through a bipolar membrane electrodialysis system to obtain sodium hydroxide and hydrochloric acid, wherein the prepared alkali is used for softening double alkali in the step (2), and the obtained acid is used for adjusting back pH before nanofiltration.
Further, the organic sulfur adopts TMT-15 water treatment agent; the flocculant adopts FeClSO4.
Further, in the step (2), the addition amount of lime and sodium carbonate is calculated according to Ca in the water quality of the wastewater entering the tubular UF membrane module 2+ Controlling the concentration of Mg at 450-650Mg/L 2+ Controlling the concentration at 200-600mg/L.
Further, in the step (3), the molecular weight cut-off of the tubular UF membrane component is 10-25 kilodaltons, the operating pressure is 1-6bar, and the diameter of the tubular membrane flow passage is 6-12mm.
In the step (4), the pH of the water produced by ultrafiltration is adjusted back by acid produced by a bipolar membrane before the water enters nanofiltration NF, so that the water is kept slightly acidic.
Further, the nanofiltration membrane component is of a roll structure, the tolerance pressure is 0-75bar, and the molecular weight cut-off is 100-400Dalton.
And (5) feeding the feed liquid after the nanofiltration water is pressurized by the booster pump into an online booster pump, and feeding the feed liquid into the RO membrane assembly after the feed liquid is further pressurized.
Further, the RO membrane assembly adopts a high-pressure-resistant disc-tube type reverse osmosis membrane assembly DTRO, MTRO or STRO, and the running pressure of the RO membrane assembly is 40-120bar.
The power plant desulfurization wastewater zero-emission treatment device capable of recycling resources comprises a three-header, a clarification tank, a reaction tank, a concentrate tank, a sludge concentrate tank, a plate-and-frame filter press, a tubular UF membrane assembly, a nanofiltration membrane assembly, an RO membrane assembly and a bipolar membrane electrodialysis system; the three-header comprises a neutralization tank, a reaction tank and a flocculation tank which are sequentially connected, wherein the flocculation tank is connected with a clarification tank, the clarification tank is connected with a reaction tank, the reaction tank is connected with a concentration water tank, a sludge outlet of the concentration water tank is connected with a sludge concentration tank, an outlet of the sludge concentration tank is connected with a plate-frame filter press, water produced by the concentration water tank is connected with a UF membrane assembly through a lift pump, water produced by the tubular UF membrane assembly is received by a filter membrane assembly, concentrated water produced by the tubular UF membrane assembly is connected with the concentration water tank, water produced by the nanofiltration membrane assembly is connected with an RO membrane assembly, concentrated water produced by the RO membrane assembly is connected with an outer calandria, and concentrated water produced by the RO membrane assembly is connected with a bipolar membrane electrodialysis system.
After the scheme is adopted, the invention has the following advantages:
the method has the advantages that firstly, a two-stage hard removal process of three-header, double-alkali softening and tubular ultrafiltration is adopted, heavy metals are better captured and removed, hardness is removed, energy consumption is low, operation cost is low, deep zero emission treatment of desulfurization wastewater of a coal-fired power plant is realized, and sodium chloride contained in the wastewater is fully utilized to directly prepare recyclable acid/alkali.
And (II) the nanofiltration can intercept multivalent ions, obtain produced water with NaCl as a main component and enter RO, and reduce the concentration burden and the scaling risk for the RO.
And (III) RO further reduces the amount of concentrated solution, improves the salt concentration so as to be beneficial to preparing acid and alkali by the bipolar membrane, and reduces the electricity consumption of preparing the acid and alkali by the bipolar membrane. The water produced after RO concentration can be recycled, and compared with the ED concentration process, the water produced by the RO concentration process has high salt content and cannot be directly recycled, and the water can be recycled only by further desalting. Therefore, the high-pressure RO concentration process is adopted, and the whole process of the system is simpler.
And fourthly, directly preparing the sodium chloride contained in the wastewater into available acid/alkali, wherein the prepared alkali is used for removing hardness by a double-alkali method, the prepared acid is used for pH callback before nanofiltration, and the surplus acid and alkali can be used in other water treatment systems of a power plant.
Drawings
FIG. 1 is a flow chart of a zero emission treatment process of desulfurization wastewater of a power plant;
FIG. 2 is a block diagram of a power plant desulfurization wastewater zero-emission treatment device.
Description of the reference numerals
Three two-tank 10 neutralization tank 101
Plate and frame filter press 60 tubular UF membrane assembly 70
Bipolar membrane electrodialysis system 100
Detailed Description
The invention is described in detail below with reference to the accompanying drawings and specific embodiments.
As shown in fig. 2, the device for zero discharge treatment of desulfurization wastewater in a power plant capable of recycling resources disclosed in this embodiment includes a three-header 10, a clarifier 20, a reaction tank 30, a concentrate tank 40, a sludge concentration tank 50, a plate-and-frame filter press 60, a tubular UF membrane module 70, a nanofiltration membrane module 80, an RO membrane module 90, and a bipolar membrane electrodialysis system 100; the three-header 10 comprises a neutralization tank 101, a reaction tank 102 and a flocculation tank 103 which are sequentially connected, wherein the flocculation tank 103 is connected with a clarification tank 20, the clarification tank 20 is connected with a reaction tank 30, the reaction tank 30 is connected with a concentrate tank 40, a sludge outlet of the concentrate tank 40 is connected with a sludge concentrate tank 50, an outlet of the sludge concentrate tank 50 is connected with a plate frame filter press 60, water produced by the concentrate tank 40 is connected with a tubular UF membrane assembly 70 through a lift pump, the tubular UF membrane assembly 70 produces water to receive a filter membrane assembly 80, concentrated water of the tubular UF membrane assembly 70 is connected with the concentrate tank 40, water produced by the nanofiltration membrane assembly 80 is connected with an RO membrane assembly 90, concentrated water produced by the nanofiltration membrane assembly 80 is connected with the reaction tank 30, water produced by the RO membrane assembly 90 is connected with an outer calandria bipolar membrane system 100.
Referring to fig. 1 and 2, the power plant desulfurization wastewater zero-emission treatment process capable of recycling resources disclosed in the embodiment includes the following steps:
(1) Pretreatment of a three-header: the wastewater is pumped into a neutralization tank 101, and Ca (OH) is added into the neutralization tank 101 2 The pH of the wastewater is adjusted to 7-9, then overflows into a reaction tank 102, organic sulfur is added into the reaction tank 102 to precipitate heavy metal ions (such as mercury, cadmium and the like), the reaction tank overflows into a flocculation tank 103, and a flocculating agent FeClSO is added into the flocculation tank 103 4 Then flows into a clarifying tank 20, and precipitates are separated to obtain clarified liquid;
the organic sulfur adopted in the embodiment is TMT-15 water treatment agent, the components of the agent contain trimercapto and triazine trisodium salt, and the agent is a high-tech water treatment agent. The product can react with various heavy metal ions (mercury, lead, copper, cadmium, nickel, manganese, zinc, chromium and the like) in the wastewater at normal temperature rapidly to generate chelate which is insoluble in water and has good chemical stability, thereby achieving the purpose of capturing and removing heavy metals.
(2) Double alkali method for removing hardness: the clarified liquid flows into a reaction tank 30, the clarified liquid reacts with lime with the mass concentration of 1.8-2.3% in the reaction tank 30, then reacts with sodium carbonate with the mass concentration of 2.0-2.5% in a coagulating liquid state, then enters a concentration water tank 40 in a coagulating liquid state, the sludge is discharged to a sludge concentration tank 50 periodically by the concentration water tank 40, the sludge is concentrated and then enters a plate-and-frame filter press 60 for filter pressing treatment to form a mud cake, the mud cake is transported or utilized periodically, and divalent and trivalent scaling ions such as calcium, magnesium and the like in the desulfurization wastewater are further removed in the step; the dosage of lime and sodium carbonate is based on Ca in the water quality of wastewater entering the tubular UF membrane module 2+ Controlling the concentration of Mg at 450-650Mg/L 2+ Controlling the concentration at 200-600mg/L.
(3) Tubular UF ultrafiltration: the water produced by the concentrate tank 40 enters a tubular UF membrane component 70 through a lift pump (not shown in the figure), the molecular weight cut-off is 10-25 kilodaltons, the operating pressure is 1-6bar, the diameter of a tubular membrane flow channel is 6-12mm, the coagulated suspension is filtered, the ultrafiltration water produced is separated and clarified, and the ultrafiltration concentrate flows back to the concentrate tank 40;
(4) Nanofiltration: the pH of the ultrafiltration water is regulated by acid produced by a bipolar membrane electrodialysis system 100, so that the pH is kept slightly acidic, then the ultrafiltration water is subjected to salt separation by a nanofiltration membrane component 80, divalent salt and TOC (total organic carbon) are intercepted by a nanofiltration membrane, the nanofiltration water mainly containing monovalent sodium chloride salt is obtained through sodium chloride and enters an RO membrane component 90 (reverse osmosis membrane component) for treatment, and the nanofiltration concentrated water is returned to the reaction tank 30 in the step (2) to remove hardness; in this step, nanofiltration membrane module 80 is of a roll-type construction, and has a pressure tolerance of 0-75bar and a molecular weight cut-off of 100-400 daltons.
(5) Reverse osmosis: the feed liquid after the nanofiltration produced water is pressurized by the booster pump enters an online booster pump, and enters an RO membrane assembly 90 after being further pressurized, the nanofiltration produced water is further concentrated by the RO membrane assembly 90, and the RO produced water is discharged or recycled; in the step, the RO membrane assembly 90 can adopt a high-pressure-resistant disc-tube type reverse osmosis membrane assembly DTRO, MTRO or STRO, the running pressure of the RO membrane assembly is 40-120bar, and the salt content can be concentrated from 30-40g/L to 100-150g/L; the reverse osmosis dialysate can be discharged up to standard, or reused and produced or prepared into water for medicament.
(6) Acid and alkali recovery: the RO concentrate is passed through a bipolar membrane electrodialysis system 100 to obtain sodium hydroxide and hydrochloric acid, the prepared base is used for double base softening in step (2), the obtained acid is used for pH adjustment before nanofiltration, and the prepared acid base can be used in other production applications.
The power plant desulfurization wastewater zero discharge treatment process has the following advantages:
A. the three-header, double-alkali softening and tubular ultrafiltration two-stage hard removal process is adopted, so that heavy metals are better captured and removed, the hardness is removed, the energy consumption is low, and the operation cost is low;
B. the acid/alkali generated by the process device is adopted, no extra acid or alkali is needed, the consumption of the medicament is reduced, and the resources are fully and reasonably utilized;
C. nanofiltration, RO concentration and bipolar membrane electrodialysis. The nanofiltration can intercept multivalent ions, and the produced water with NaCl as a main component enters RO, so that the concentration burden and the scaling risk are reduced for the RO, the amount of concentrated solution is further reduced by the RO, the salt concentration is improved so as to be beneficial to the preparation of acid and alkali by the bipolar membrane, and the power consumption of the preparation of the acid and alkali by the bipolar membrane is reduced;
and D, the produced water after RO concentration can be recycled, and compared with ED concentration process produced water, the produced water often has higher salt content and cannot be directly recycled, and the produced water can be recycled only by further desalting. Therefore, the high-pressure RO concentration process is adopted, and the whole process of the device is simpler.
See the following table for detailed parameters of the individual processing steps of this example.
As can be seen from RO concentrated water and produced water, the zero discharge treatment process of the desulfurization wastewater of the power plant with the resource recycling function can effectively remove COD, SS and Mg in the desulfurization wastewater of the power plant 2+ 、SiO 2 And divalent ions are generated to produce a large amount of alkali and acid, so that the resource recycling and the zero discharge of wastewater are realized.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention.
Claims (9)
1. The zero discharge treatment process of the desulfurization wastewater of the power plant capable of recycling resources is characterized by comprising the following steps of:
(1) Pretreatment of a three-header: pumping the wastewater into a neutralization tank, and adding Ca (OH) into the neutralization tank 2 Adjusting the pH of the wastewater to 7-9, then overflowing the wastewater into a reaction tank, adding organic sulfur to precipitate heavy metal ions, overflowing the reaction tank into a flocculation tank, adding a flocculating agent into the flocculation tank, and then flowing into a clarification tank to separate out precipitate to obtain clarified liquid;
(2) Double alkali method for removing hardness: reacting the clarified liquid with lime with the mass concentration of 1.8-2.3% in a reaction tank, then reacting with sodium carbonate with the mass concentration of 2.0-2.5% in a coagulating liquid state, then entering a concentrating water tank in the coagulating liquid state, periodically discharging sludge outside the concentrating water tank to a sludge concentrating tank, concentrating the sludge, and then entering a plate-and-frame filter press for filter pressing treatment to form mud cakes, thereby further removing bivalent and trivalent scaling ions in the desulfurization wastewater;
(3) Tubular UF ultrafiltration: the water produced by the concentration water tank enters a tubular UF membrane component through a lifting pump, the suspended matters after coagulation are filtered, ultrafiltration water produced is obtained through separation and clarification, and ultrafiltration concentrated water flows back to the concentration water tank;
(4) Nanofiltration: separating salt by a nanofiltration membrane component after ultrafiltration water production is returned to be acidic, intercepting divalent salt and TOC by the nanofiltration membrane, obtaining water mainly containing monovalent sodium chloride salt by sodium chloride permeation, treating the water by an RO membrane component, and returning concentrated water to the reaction tank in the step (2);
(5) Reverse osmosis: further concentrating the nanofiltration produced water by using an RO membrane assembly, and discharging or recycling the RO produced water;
(6) Acid and alkali recovery: and (3) passing the RO concentrated water through a bipolar membrane electrodialysis system to obtain sodium hydroxide and hydrochloric acid, wherein the prepared sodium hydroxide is used for removing hardness by a double-alkali method in the step (2), and the pH value of the obtained hydrochloric acid is adjusted back before the obtained hydrochloric acid is used for entering a nanofiltration membrane component.
2. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: the organic sulfur adopts TMT-15 water treatment agent, and the flocculant adopts FeClSO 4 。
3. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: in the step (2), the dosage of lime and sodium carbonate is based on Ca in the water quality of wastewater entering the tubular UF membrane module 2+ Controlling the concentration of Mg at 450-650Mg/L 2+ Controlling the concentration at 200-600mg/L.
4. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: in the step (3), the molecular weight cut-off of the tubular UF membrane component is 10-25 kilodaltons, the operating pressure is 1-6bar, and the flow passage diameter of the tubular UF membrane component is 6-12mm.
5. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: in the step (4), the pH value of the ultrafiltration water is adjusted back by using the acid produced by the bipolar membrane electrodialysis system before the ultrafiltration water enters the nanofiltration membrane assembly, so that the pH value is kept slightly acidic.
6. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: the nanofiltration membrane component is of a roll structure, the tolerance pressure is 0-75bar, and the molecular weight cut-off is 100-400Dalton.
7. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: and (5) feeding the feed liquid after the nanofiltration water is pressurized by the booster pump into an online booster pump, and feeding the feed liquid into the RO membrane assembly after further pressurization.
8. The zero-emission treatment process for desulfurization wastewater of a power plant capable of recycling resources according to claim 1, which is characterized in that: the RO membrane component adopts a high-pressure-resistant disc-tube type reverse osmosis membrane component DTRO, MTRO or STRO, and the running pressure of the RO membrane component is 40-120bar.
9. A treatment device applied to the zero emission treatment process of the power plant desulfurization wastewater capable of recycling resources according to any one of claims 1 to 8, which is characterized in that: comprises a three-header, a clarification tank, a reaction tank, a concentration water tank, a sludge concentration tank, a plate-and-frame filter press, a tubular UF membrane component, a nanofiltration membrane component, an RO membrane component and a bipolar membrane electrodialysis system; the three-header comprises a neutralization tank, a reaction tank and a flocculation tank which are sequentially connected, wherein the flocculation tank is connected with a clarification tank, the clarification tank is connected with a reaction tank, the reaction tank is connected with a concentration water tank, a sludge outlet of the concentration water tank is connected with a sludge concentration tank, an outlet of the sludge concentration tank is connected with a plate-frame filter press, water produced by the concentration water tank is connected with a UF membrane assembly through a lift pump, water produced by the tubular UF membrane assembly is received by a filter membrane assembly, concentrated water produced by the tubular UF membrane assembly is connected with the concentration water tank, water produced by the nanofiltration membrane assembly is connected with an RO membrane assembly, concentrated water produced by the RO membrane assembly is connected with an outer calandria, and concentrated water produced by the RO membrane assembly is connected with a bipolar membrane electrodialysis system.
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