CN107365021B - Ammonium recovery and zero discharge technology and system for vanadium-titanium wastewater - Google Patents

Ammonium recovery and zero discharge technology and system for vanadium-titanium wastewater Download PDF

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CN107365021B
CN107365021B CN201710652561.3A CN201710652561A CN107365021B CN 107365021 B CN107365021 B CN 107365021B CN 201710652561 A CN201710652561 A CN 201710652561A CN 107365021 B CN107365021 B CN 107365021B
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wastewater
tank
water
inlet end
heat exchanger
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CN107365021A (en
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刘艺
王信
王长昊
高舒乐
刘昕
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Shanghai Weilai Enterprise Co ltd
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Shanghai Weilai Enterprise Co ltd
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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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/16—Halides of ammonium
    • C01C1/164—Ammonium chloride
    • 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
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • 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
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/041—Treatment of water, waste water, or sewage by heating by distillation or evaporation by means of vapour compression
    • 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
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
    • 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
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • 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
    • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56—Macromolecular compounds
    • 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
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C02F3/1236—Particular type of activated sludge installations
    • C02F3/1268—Membrane bioreactor systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Abstract

The invention provides an ammonium recovery and zero discharge technology for titanium alum wastewater, which is characterized by comprising a precipitation process, a deamination process, a steam condensation process and a COD removal process; in the precipitation process, under the action of a coagulant and a flocculant, the wastewater is removed after the colloidal substances and the suspended solid substances are coagulated and precipitated; in the deamination process, ammonia is removed from the wastewater under the action of chemical extraction; in the steam condensation process, heavy metal and salt in the wastewater are removed in a mode of evaporating and condensing the water in the wastewater; in the COD removing process, COD is removed from the wastewater by a water treatment technology combining an activated sludge method and a membrane separation technology. The method can treat the wastewater to recycle the wastewater, can also obtain the ammonium chloride used in the manufacturing process, and realizes the effect of zero emission.

Description

Ammonium recovery and zero discharge technology and system for vanadium-titanium wastewater
Technical Field
The invention relates to the field of water treatment equipment, in particular to an ammonium recovery and zero discharge technology for titanium alum wastewater and a system capable of applying the technology.
Background
The vanadium-titanium wastewater is mainly generated in the vanadium extraction process of vanadium titano-magnetite. The main characteristics of the waste water comprise high ammonia nitrogen, high heavy metal and high salt. Because of the high salinity of wastewater, which has the effect of inhibiting the growth and reproduction of microorganisms, the application of direct biological treatment is very limited and is basically excluded from the conventional treatment process. The currently more common treatment method is a two-stage or three-stage process combination of the following processes:
chemical precipitation method: heavy metals are removed by adding a precipitator into the wastewater and forming precipitates through the precipitator and the heavy metal ions. The main disadvantages are that: a large amount of sediments are generated, and the sediments are transported and treated by qualified units as dangerous wastes, are expensive and are limited by the treatment capacity of the qualified treatment units of third parties.
An adsorption method: the heavy metal ions in the water are physically or chemically adsorbed through the high specific surface area structure or special functional groups of the adsorption material. The main disadvantages are that: the adsorption equilibrium time is long, the treatment efficiency is low, and a plurality of hours are often needed to achieve a good adsorption effect.
A stripping method: adjusting pH by adding base to make ionic ammonia (NH)4 +) The free ammonia is converted, then the steam or the air is introduced for desorption, and the ammonia is converted into a gas phase from a water phase, thereby achieving the purpose of removing the ammonia nitrogen. The main disadvantages are that: the device is greatly influenced by environmental factors (temperature, pH, gas-liquid ratio, oil substances and surfactant), has a good stripping effect only by introducing external steam, and has high power consumption.
Secondary chemical precipitation: magnesium salt and phosphate are added into the ammonia nitrogen wastewater to generate magnesium ammonium phosphate crystal precipitate under alkaline condition, so that ammonia Nitrogen (NH) in water is removed4 +-N). The main disadvantages are that: a large amount of phosphate and magnesium salt agents are required to be added, the control condition of the generated magnesium ammonium phosphate precipitate is harsh, a large amount of precipitate is generated, and the ammonia can not be recycled.
Membrane separation method: under certain pressure, when the raw liquid flows through the membrane surface, the dense micropores only allow water and small molecular substances to pass through to become permeate, and the substances with the volume larger than the micropore diameter of the membrane surface in the raw liquid are trapped on the liquid inlet side of the membrane to become concentrated liquid, so that the separation and concentration of the raw liquid are realized. The main disadvantages are that: the pretreatment of the wastewater before entering the membrane is high in requirement, high pressure needs to be applied, technical requirement is high, and the yield of fresh water is low. The rear end of the concentrated water still needs to be connected with external evaporation concentration equipment to carry out desalination treatment on the concentrated water.
An evaporation method: the solute concentration is increased by volatilization of the solvent under the action of external energy, so that a supersaturated solution is obtained, and the crystal growth is realized. The main disadvantages are that: the conventional evaporation method directly uses electric heating or uses steam as energy, so that the energy consumption is high, and the waste water often contains higher chloride ions, so that the equipment is easy to corrode and is difficult to maintain.
COD residue: through the two-stage or three-stage combination of the conventional processes, the standard discharge of the vanadium-titanium wastewater can be basically realized. However, because a certain amount of volatile organic substances are carried in the evaporation process, the evaporated wastewater still has a certain amount of COD substances. The method is also a problem of the conventional treatment process of the titanium alum wastewater, except for adopting an RO membrane method, other combinations are all beneficial.
Disclosure of Invention
The invention mainly aims at the wastewater containing high salt content, high heavy metal content, high ammonia nitrogen content, high chloride ion content and high sulfate radical content generated in the vanadium-titanium wastewater production process, aims to overcome the defects, can realize zero discharge, can realize ammonium recovery of vanadium-titanium wastewater by removing ammonia nitrogen and preparing ammonium chloride for recycling in the production process, can obtain reuse water for the production process by means of gradual purification, and further realizes energy conservation, environmental protection and purification and reuse of partial solute in the wastewater and the wastewater.
The invention provides an ammonium recovery and zero discharge technology for titanium alum wastewater, which is characterized by comprising a precipitation process, a deamination process, a steam condensation process and a COD removal process;
in the precipitation process, the wastewater is subjected to coagulation precipitation of the colloidal substances and the suspended solids under the action of a coagulant and a flocculant and then is removed;
in this step, the coagulant is generally a PAC coagulant and the flocculant is generally a PAM flocculant, both of which are inexpensive and readily available. And in the scheme of the invention, the coagulating sedimentation process is carried out without adding other chemical auxiliary agents.
In the process, the wastewater is coagulated and precipitated, and under the action of a coagulant and a flocculant, colloids and fine suspended matters (such as heavy metal precipitates or other inorganic precipitates) in the wastewater are coagulated into floccules and clarified and removed under the action of gravity. Meanwhile, with the rising of the pH value of the wastewater, partial hydroxide generated by heavy metal is removed by precipitation. The method is used as a pretreatment process of an AEM deamination process, does not need to add a new chemical precipitator, and is mainly used for removing the original SS solid suspended substance impurities in wastewater.
In the deamination process, ammonia is removed from the wastewater under the action of chemical extraction;
namely, after the coagulating sedimentation effluent enters a deamination process, the chemical extraction is taken as the normal temperature evaporation process of reaction driving force, and in the process, the ammonia radical ions (NH) in the wastewater4 +) For mixing with waterHydroxyl radical (OH) of (1)-) The reaction is carried out to convert the ammonia gas into free ammonia molecules (NH) in the ammonia gas and the wastewater3) After being separated, the wastewater reacts with an acid solution or gas, thereby realizing the removal of ammonia molecules or ions in the wastewater without external energy.
In the steam condensation process, heavy metal and salt in the wastewater are removed by evaporating and condensing the water in the wastewater;
in the process, while the moisture in the wastewater is continuously evaporated, heavy metal and salt in the wastewater are separated out in a form of crystals and removed, and then the evaporated water vapor is condensed and condensed into water again to enter the next process.
In the above-mentioned COD removal step, COD is removed from the wastewater by a water treatment technique combining an activated sludge process and a membrane separation technique.
Further, the technology for recovering ammonium from titanium alum wastewater and realizing zero discharge is characterized in that ammonium ions in the wastewater are converted into gaseous ammonia in the deamination procedure and then react with hydrochloric acid to form ammonium chloride.
In addition, the invention also provides an ammonium recovery and zero discharge system for the vanadium-titanium wastewater, which is characterized by comprising a precipitation system, a deamination system, an evaporation and condensation system and a COD removal system;
the precipitation system, the deamination system, the evaporation and condensation system and the COD removal system are sequentially arranged along the flowing direction of the wastewater;
the circulation of the waste water among the devices can be realized through the liquid conveying pipes and the liquid pumps among the systems, and the circulation of the waste water can also be realized through the water level difference among the systems.
The sedimentation system is used for removing colloidal substances and solid suspended substances in the wastewater;
the deamination system is used for removing ammonia radical ions (NH) in wastewater4 +) And ammonia molecules (NH)3)；
The evaporation and condensation system is used for removing heavy metals and salt in the wastewater;
the COD removing system is used for removing COD in the wastewater.
Further, the ammonium recovery and zero discharge system for the titanium alum wastewater provided by the invention is also characterized in that the precipitation system comprises a coagulation unit, a flocculation unit and a precipitation unit which are sequentially arranged;
the coagulation unit comprises a coagulation tank and coagulant dosing equipment;
the flocculation unit comprises a flocculation tank and a flocculating agent dosing device;
the sedimentation unit comprises a sedimentation tank;
the coagulant adding equipment adds coagulant into the coagulation tank;
the flocculant dosing equipment feeds a flocculant into the flocculation tank;
the mixing mechanism is arranged in the coagulation tank and the flocculation tank. The stirring mechanism can be any stirring structure, such as: paddle, stir plate, magnetic stirrer, etc. may serve as a means for stirring the liquid to uniformly mix the solvent/solute therein.
In addition, as a preferable example, the sedimentation tank may further include a filter screen or the like for separating solid substances from liquid, and a sludge pump or the like for pumping out concentrated solid substances such as sludge or the like at the bottom thereof.
Further, the ammonium recovery and zero discharge system for the vanadium-titanium wastewater provided by the invention is also characterized in that the precipitation system further comprises at least one re-filtering unit; the re-filtering unit is generally arranged behind the precipitation unit and is used for removing ultrafine particles which cannot be completely precipitated and filtered by a common filtering and precipitation unit.
The above-mentioned refiltering unit includes refiltering equipment;
the inside of the secondary filtering equipment is provided with a superfine filtering mechanism; such as: a filter screen, etc.
The superfine filtering mechanism can be used for filtering substances with the particle size of 10-100 microns.
Further, the ammonium recovery and zero discharge system for the vanadium-titanium wastewater provided by the invention is also characterized in that the deamination system comprises deamination equipment and a reaction tank; the deamination system can be a processing device/system of similar function and structure such as an AEM processing system;
wherein, an ammonia filtering mechanism is arranged in the deamination equipment and is used for separating gaseous ammonia molecules in the wastewater; the filter structure is typically a membrane structure that allows gaseous substances to pass through, but blocks liquids and the like from passing through.
After the gaseous ammonia molecules are separated, the gaseous ammonia molecules enter a reaction tank;
an acid solution is arranged in the reaction tank. In order to realize the characteristic of process recycling, the acid solution is generally hydrochloric acid solution, and the hydrochloric acid can react with ammonia gas to generate ammonium chloride, thereby realizing the effect of process recycling.
The acidic solution is typically an aqueous solution of an acid having a mass concentration of 15-30%.
The acidic solution may be replenished and added by additional acid addition equipment.
When the ammonium salt solution after the reaction reaches the quality concentration requirement of recycling, filtering or refining the ammonium salt solution by a filter and other equipment to obtain the ammonium salt solution for recycling.
In the process equipment, the wastewater flows through a channel on one side of the membrane, and the hydrochloric acid solution flows through the other side of the membrane. Ammonium ions in the wastewater side combine with hydroxide in the water to form gaseous ammonia molecules, which permeate the membrane to enter the hydrochloric acid side and combine with hydrochloric acid to form the ammonium chloride solution used in the process. While water molecules and other heavy metal ions, etc. cannot permeate the membrane. In the process, ammonia on the wastewater side continuously permeates the membrane, and the ammonia on the wastewater side is removed and recovered by the hydrochloric acid side. The method is a normal-temperature evaporation process taking chemical extraction as a reaction driving force, and does not need additional energy.
Further, the ammonium recovery and zero discharge system for the vanadium-titanium wastewater provided by the invention is also characterized in that the evaporation and condensation system comprises a heater and a condensation separator;
wherein, the heater heats and evaporates the flowing waste water;
the condensation separator condenses the waste water vapor and separates out the distilled water in the waste water vapor.
Further, the ammonium recovery and zero discharge system for the titanium alum wastewater provided by the invention is also characterized in that the evaporation and condensation system comprises a preheater, a heat exchanger, a separator and a compressor; such as: mechanical vapor recompression and other similar heat exchange technologies;
the preheater comprises a first waste liquid inlet end, a second waste liquid outlet end, a third low-temperature steam inlet end and a fourth distilled water outlet end;
the heat exchanger comprises a first liquid inlet end, a second liquid outlet end, a third liquid inlet end and a fourth liquid outlet end;
the separator comprises a separation chamber, an air inlet/water inlet end and a secondary wastewater discharge end;
the compressor comprises an inlet end and an outlet end;
the first waste liquid inlet end of the preheater is communicated with the waste water outlet end of the deamination system, and waste water is introduced into the preheater for preheating;
the second waste liquid outlet end is communicated with the first liquid inlet end of the heat exchanger, and preheated waste water is fed into the heat exchanger;
the second liquid outlet end of the preheater is communicated with the gas inlet/water inlet end of the separator, and the heated residual wastewater crystallization saturated liquid is sent into the separation chamber;
the low-temperature steam/water outlet end is connected with the inlet end of the compressor, and low-temperature steam is sent into the compressor;
the outlet end of the compressor is connected with the third inlet end of the heat exchanger, and high-temperature and high-pressure gas compressed by the compressor is sent to the heat exchanger;
the fourth low-temperature steam end of the heat exchanger is connected with the third distilled water inlet end of the preheater, and the secondary steam after heat exchange and temperature reduction by the heat exchanger is sent into the preheater and is sent into the COD removing system through the fourth distilled water outlet end of the preheater.
In the system, the general process is that the waste water is preheated (or exchanges heat with return secondary steam) to reach the temperature of 30-40 ℃, then the waste water is sent into a heat exchanger through equipment such as a pump and the like to exchange heat with the return high-temperature steam and then is converted into high-temperature steam, the residual waste water crystallization saturated liquid after the high-temperature heat exchange and the generated low-temperature steam are separated by a separator in a cold-heat/solid-liquid mode, solid matters such as salt and the like in the waste water crystallization saturated liquid are separated in a centrifugal mode, wherein the low-temperature steam enters a compressor to act as high-temperature high-pressure gas, and after passing through the heat exchanger, the low-temperature steam exchanges heat with the return low-temperature liquid and then is converted into low-temperature secondary steam, the low-temperature secondary steam is transferred into a preheater to exchange heat with.
Therefore, in the process, the effluent of the deamination process enters the unit, and low-grade steam is improved into a high-grade steam heat source through mechanical work of a compressor by utilizing secondary steam and energy thereof generated by an evaporation system. The circulation provides heat energy for the evaporation system, thereby reducing the requirement on external energy. The water in the system is continuously evaporated, and heavy metals and salt in the wastewater are separated out in a form of crystals and removed. The evaporated water vapor is condensed again to water.
Further, the ammonium recovery and zero discharge system for the titanium alum wastewater provided by the invention is also characterized in that the separator also comprises a return water outlet;
the reflux water outlet is connected with the first liquid inlet end of the heat exchanger. Thereby the liquid separated in the solid-liquid separation process can be refluxed and evaporated.
Further, the ammonium recovery and zero discharge system for titanium alum wastewater provided by the invention is also characterized in that the COD removal system comprises a COD removal tank, an MBR membrane, a recycling tank and/or a backwashing system;
the MBR membrane is arranged in the COD removing tank;
the water treated by the MBR membrane enters a recycling tank;
wherein, the back washing system is arranged on a pipeline communicated with the COD removing tank and the recycling tank.
Because a certain amount of volatile organic substances are carried in the evaporation process of the previous step, the evaporated wastewater still has certain COD substances. The COD system is removed in the access of condensation effluent (a water treatment technology that combines together by activated sludge process and membrane separation technology), because the salinity in the anterior segment waste water has basically been got rid of, and the microorganism has higher biological activity in low salinity environment, combines the combination of membrane, goes out water high-quality stable, and area is little, ensures that last reuse water effluent index is superior to reuse water quality of water.
Further, the ammonium recovery and zero discharge system for titanium alum wastewater provided by the invention has the characteristics that a pH adjusting tank or a reclaimed water collecting tank is arranged before or after each system.
Wherein, the pH adjusting tank is generally arranged at the foremost end of the system and is used for adjusting the pH of the wastewater to 10-11, thereby realizing better precipitation flocculation effect.
The reclaimed water collecting tank is used for collecting and storing water entering or exiting in a certain process.
The invention has the following functions and effects:
the ammonium recovery and zero discharge technology for the vanadium-titanium wastewater adopts a new process route form completely different from a secondary process route (a stripping method/secondary chemical precipitation): the method comprises the steps of removing impurities such as SS in the wastewater by coagulating sedimentation, removing ammonia by deamination (realizing on-line ammonium chloride recovery), desalting and removing heavy metals by a mechanical steam recompression technology, and removing organic matters evaporated from the wastewater by a membrane bioreactor.
The process method has the following technical advantages:
1. in the first-stage process, other chemical precipitating agents are not added into the wastewater to precipitate ionic heavy metals or other inorganic ions in the wastewater, so that a large amount of sediments cannot be generated in the system;
2. the first-stage process adopts a chemical reaction form, the reaction time is short, and the treatment efficiency is high;
3. in the secondary process, chemical extraction is used as a reaction driving force in the normal-temperature evaporation process, no external energy is needed, the defect of high power consumption of the stripping method is overcome, and the influence of the environment is lower than that of the stripping method;
4. compared with a secondary chemical precipitation method, the method recovers the ammonia in the wastewater and directly applies the ammonia to the manufacturing process, thereby saving resources. Rather than converting the ammonium to crystalline magnesium ammonium phosphate precipitates as in the secondary precipitation method and taking into account the export of magnesium ammonium phosphate;
5. the energy consumption requirement of the system is lower than that of the conventional evaporation process, and the low-grade steam is improved into a high-grade steam heat source through mechanical work of a compressor by utilizing secondary steam and energy thereof generated by the evaporation system. The circulation provides heat energy for the evaporation system, thereby reducing the requirement on external energy.
6. Compared with the membrane separation technology, the method has the advantages that no concentrated water is used, salt in the wastewater is directly crystallized and separated out, the water yield is higher, and the technical requirement is lower;
7. the biological treatment process is added at the final end of the process, so that the problem that the quality COD of the reuse water exceeds the standard in the conventional process combination is solved. Meanwhile, because the salt in the front-stage wastewater is basically removed, the microorganisms have higher biological activity in a low-salt environment, and the effluent is high-quality and stable by combining the combination of membranes.
Drawings
FIG. 1 shows a schematic structural diagram of an ammonium recovery and zero discharge system for titanium alum wastewater in this embodiment.
Detailed Description
As shown in fig. 1, the embodiment provides an ammonium recovery and zero discharge system for titanium alum wastewater, which adopts the technology of removing ammonia by an AEM membrane method and recovering ammonium chloride on line; the system adopts an MVR mechanical vapor recompression dominant evaporation desalination technology; the system adopts the technology of removing COD in wastewater by adopting an MBR (membrane bioreactor), and comprises a pH adjusting system, a precipitation system, a deamination system, an evaporation and condensation system and a COD removing system;
the wastewater is pumped out from the regulating reservoir 1 through the regulating reservoir lifting pump 2, and then flows through the pH regulating system, the precipitation system, the deamination system, the evaporation and condensation system and the COD removal system in sequence to be recycled.
The pH adjusting system is used for adjusting the pH of the wastewater to a prescribed pH value, which is required to be 10 to 11 in this embodiment.
The pH adjusting system consists of a pH adjusting tank 3, a pH adjusting tank stirrer 4 and a sodium hydroxide dosing system 12. Wherein, this pH equalizing basin mixer 4 installs in pH equalizing basin 3, and this sodium hydroxide medicine system 12 and pH equalizing basin 3 intercommunication add sodium hydroxide in to pH equalizing basin 3 through the pipeline.
In this embodiment, the wastewater is continuously pumped into the pH adjusting tank 3, and simultaneously, the sodium hydroxide adding system 12 also adds sodium hydroxide into the pH adjusting tank 3 to adjust the pH of the wastewater, and in the mixing process, the sodium hydroxide and the wastewater are fully mixed by the pH adjusting tank stirrer 4, and after reaching a specified pH value, the wastewater flows into the precipitation system through a pipeline, a liquid pump or a water potential difference.
The sedimentation system is used for removing colloidal substances and solid suspended substances in the wastewater.
The sedimentation system consists of a coagulation unit, a flocculation unit, a sedimentation unit and a re-separation unit, wherein the coagulation unit consists of a coagulation tank 5, a coagulation tank stirrer 6 and a PAC dosing system 13, the coagulation tank stirrer 6 is arranged in the coagulation tank 5, the PAC dosing system 13 is communicated with the coagulation tank 5, and a coagulant PAC is added into the coagulation tank 5 through a pipeline; the flocculation unit consists of a flocculation tank 7, a flocculation tank stirrer 8 and a PAM dosing system 14, wherein the flocculation tank stirrer 8 is arranged in the flocculation tank 7, the PAM dosing system 14 is communicated with the flocculation tank 7, and a flocculating agent PAM is added into the flocculation tank 7 through a pipeline; the sedimentation unit consists of a sedimentation tank 9, a sedimentation tank sludge pump 10 and a water production tank 11, wherein the sedimentation tank sludge pump 10 is arranged at the bottom outlet of the sedimentation tank 9; the re-separation unit consists of a lift pump 15 and a filter 16.
In this embodiment, after the wastewater flows out of the pH adjusting tank 3, the wastewater enters the coagulation tank 5 through a pipeline, a liquid pump or a water potential difference, and the like, meanwhile, the PAC dosing system 13 adds the PAC coagulant into the coagulation tank 5, in the mixing process, the coagulant and the wastewater are fully mixed by the coagulation tank mixer 6, the wastewater flows into the flocculation tank 7 through a pipeline, a liquid pump or a water potential difference, meanwhile, the PAM dosing system 14 adds the PAM flocculant into the flocculation tank 7, in the mixing process, the flocculant and the wastewater are fully mixed by the flocculation tank mixer 8, the wastewater flows into the sedimentation tank 9 through a pipeline, a liquid pump or a water potential difference for sedimentation, the precipitated sludge concentrate is pumped into the sludge concentration tank through the sedimentation tank sludge pump 10 for subsequent treatment, and the treated wastewater flows into the production tank 11 for treatment water collection, then the wastewater is pumped into a filter 16 through a lift pump 15, superfine impurities are removed through a superfine filter screen (with the aperture of 10-30 microns) in the filter 16, and the removed wastewater flows into a deammoniation system;
the deamination system is used for removing ammonia in various forms in wastewater.
The deamination system comprises an AEM module 17, an ammonium chloride circulating pump 18, an ammonium chloride circulating water tank 19, an ammonium chloride recycling water pump 20 and a hydrochloric acid dosing system 22, wherein the ammonium chloride circulating pump 18 is communicated with the AEM module 17, the ammonium chloride recycling water pump 20 is installed at the bottom of the ammonium chloride circulating water tank 19, the upper end of the AEM module 17 is communicated with the ammonium chloride circulating water tank 19, and the hydrochloric acid dosing system 22 adds hydrochloric acid with the mass percentage concentration of 10-30% into the ammonium chloride circulating water tank 19 through equipment such as a pipeline;
in this embodiment, the wastewater flows out of the filter 16 and enters the AEM module 17, in the AEM module 17, the wastewater passes through a channel on one side of the AEM membrane, the other side of the AEM membrane is introduced into the ammonium chloride circulating water tank 19, ammonium ions in the wastewater side combine with hydroxide in water to form gaseous ammonia molecules, the gaseous ammonia molecules penetrate through the AEM membrane and enter the ammonium chloride circulating water tank 19 and react with hydrochloric acid in the tank to form ammonium chloride used in the process, and water molecules and other heavy metal ions and the like cannot penetrate through the AEM membrane. In the process, ammonia in the wastewater continuously permeates through the AEM membrane and is recovered by hydrochloric acid, and the wastewater after the deamination process flows into and is pumped into an AEM water production tank 21 and then is pumped into an evaporation and condensation system by a lifting pump 23;
the evaporation and condensation system is used for removing heavy metals in the wastewater;
the evaporation and condensation system consists of a preheater 24, a circulating pump 25, a main heat exchanger 26, a vapor compressor 27 and a separator 28;
in this embodiment, after the wastewater is pumped into the evaporative condensation system, the wastewater firstly enters the preheater 24, is preheated to 30-40 ℃ by the preheater 24, is pumped into the main heat exchanger 26 by the circulating pump 25, is heated to 80-100 ℃ by heat exchange, the residual crystallization supersaturated solution enters the separator 28 for solid-liquid separation, inorganic metal salts such as sodium sulfate and the like separated in the solid-liquid separation process are transported out of the equipment, the vapor liquid is cooled to about 30-40 ℃ at this time, and is sent into the vapor compressor 27, the high-temperature high-pressure vapor compressed by the compressor 27 again enters the main heat exchanger 26 for heat exchange with the wastewater in the process, while heating the wastewater in the process, the vapor is cooled, and the low-temperature or normal-temperature distilled water obtained after heat exchange by the preheater 24 again enters the COD removal system;
the COD removing system is used for removing COD in wastewater.
The COD removing system comprises an MBR unit and a backwashing unit. The MBR unit consists of a Roots blower 29, an MBR membrane tank 30, an MBR membrane 31, an MBR tank sludge pump 32, a sludge concentration tank 33, a sludge concentration tank sludge pump 34 and a sludge press filtration system 38; wherein, the MBR membrane 31 is arranged in the MBR membrane tank 30, and the Roots blower 29 is electrically connected with the MBR membrane 31; the backwashing unit comprises a backwashing pump 35, a reuse water tank 36, a reuse water pump 37, an acid washing system 39, an alkali washing system 40 and a sodium hypochlorite system 41, wherein the backwashing pump 35 is arranged on a pipeline connecting the reuse water tank 36 and the water outlet end of the MBR membrane 31.
In this embodiment, the distilled water after the condensation passes through in equipment such as pipeline gets into MBR membrane cisterna 30, get rid of COD through MBR membrane 31's effect, the water of output gets into in the retrieval and utilization pond 36 for use through the pipeline, through backwash pump 35 on this pipeline in proper order through pickling system 39, avoided the pipeline to block up scheduling problem after the effect of alkali wash system 40 and sodium hypochlorite system 41, in MBR membrane cisterna 30, sediment in the sludge concentration pond 33 is gone into by the pump through MBR pond sludge pump 32 by residues such as mud that the production process produced, later concentrated mud compresses in getting into sludge press filtration system 38 through sludge concentration pond sludge pump 34.
The ammonium recovery and zero discharge technology of the vanadium-titanium wastewater provided by the embodiment provides a new vanadium-titanium wastewater treatment process combination form, and compared with the conventional combination process form, the vanadium-titanium wastewater treatment process combination form has the following characteristics:
1. in the conventional vanadium-titanium wastewater which can not adopt the biological treatment technology, the effective application of the biological treatment technology is realized through the pretreatment of a front stage, and the vanadium-titanium wastewater is used as a final treatment process, so that the final effluent is high in quality and stable, and the COD exceeding phenomenon possibly occurring in the conventional treatment process is avoided;
2. in the whole process, no additional precipitator such as heavy metal precipitator, magnesium salt, phosphate and the like is added into the system, no additional chemical sludge or by-product is brought to the whole process system, higher wastewater treatment cost caused by consignment and outward transportation of more chemical sludge is avoided, and higher economic benefit is achieved. Worries about the distribution of the by-product magnesium ammonium phosphate;
3. the ammonia in the vanadium-titanium wastewater is recycled and is manufactured into an ammonium chloride product which can be directly used for production on line, so that the recycling of resources is realized, and waste is changed into valuable;
4. the application of the MVR technology saves energy consumption in the whole wastewater system and saves the operation cost of wastewater treatment.

Claims (3)

1. An ammonium recovery and zero discharge system for titanium alum wastewater is characterized by comprising a pH adjusting system, a precipitation system, a deamination system, an evaporation and condensation system and a COD removing system;
the pH adjusting system, the precipitation system, the deamination system, the evaporation and condensation system and the COD removing system are sequentially arranged along the flowing direction of the wastewater;
the sedimentation system is used for removing colloidal substances and solid suspended substances in the wastewater;
the deamination system is used for removing ammonia in various forms in the wastewater;
the evaporation and condensation system is used for removing heavy metals and salt in the wastewater;
the COD removing system is used for removing COD in the wastewater;
the sedimentation system comprises a coagulation unit, a flocculation unit and a sedimentation unit which are arranged in sequence;
the coagulation unit comprises a coagulation tank and coagulant dosing equipment;
the flocculation unit comprises a flocculation tank and a flocculating agent dosing device;
the sedimentation unit comprises a sedimentation tank;
the coagulant adding equipment adds coagulant into the coagulation tank;
the flocculant dosing equipment feeds a flocculant into the flocculation tank;
stirring mechanisms are arranged in the coagulation tank and the flocculation tank;
the sedimentation system further comprises at least one re-filtration unit;
the refilter unit includes a refilter device;
the inside of the secondary filtering equipment is provided with a superfine filtering mechanism;
the superfine filtering mechanism can be used for filtering substances of 10-100 micrometers;
the pH adjusting system consists of a pH adjusting tank, a pH adjusting tank stirrer and a sodium hydroxide dosing system; the pH adjusting tank stirrer is arranged in the pH adjusting tank, the sodium hydroxide dosing system is communicated with the pH adjusting tank, and sodium hydroxide is added into the pH adjusting tank through a pipeline;
the deamination system comprises deamination equipment and a reaction tank;
wherein, an ammonia filtering mechanism is arranged in the deamination equipment and is used for separating gaseous ammonia molecules in the wastewater;
after the gaseous ammonia molecules are separated, the gaseous ammonia molecules enter a reaction tank;
an acid solution is arranged in the reaction tank;
the evaporation and condensation system comprises a preheater, a heat exchanger, a separator and a compressor;
the preheater comprises a first waste liquid inlet end, a second waste liquid outlet end, a third low-temperature steam inlet end and a fourth distilled water outlet end;
the heat exchanger comprises a first liquid inlet end, a second liquid outlet end, a third liquid inlet end and a fourth low-temperature steam end;
the separator comprises a low-temperature steam/water outlet discharge end, a separation chamber, an air inlet/water inlet end and a secondary wastewater discharge end;
the compressor comprises an inlet end and an outlet end;
the first waste liquid inlet end of the preheater is communicated with the waste water outlet end of the deamination system, and waste water is introduced into the preheater for preheating;
the second waste liquid outlet end is communicated with the first liquid inlet end of the heat exchanger, and preheated waste water is fed into the heat exchanger;
the second liquid outlet end of the heat exchanger is communicated with the gas inlet/water inlet end of the separator, and the heated residual wastewater crystallization saturated liquid is sent to the separation chamber;
the low-temperature steam/water outlet end is connected with the inlet end of the compressor, and low-temperature steam is sent into the compressor;
the outlet end of the compressor is connected with the third inlet end of the heat exchanger, and high-temperature and high-pressure gas compressed by the compressor is sent to the heat exchanger; the fourth low-temperature steam end of the heat exchanger is connected with the third low-temperature steam inlet end of the preheater, secondary steam after heat exchange and temperature reduction by the heat exchanger is sent into the preheater, and is sent into the COD removing system through the fourth distilled water outlet end of the preheater;
the COD removing system comprises a COD removing tank, an MBR membrane, a recycling tank and a backwashing system;
the MBR membrane is arranged in the COD removing tank;
the water treated by the MBR membrane enters a recycling tank;
wherein, the back flush system is arranged on a pipeline communicated with the COD removing tank and the recycling tank.
2. The ammonium recovery and zero discharge system of titanium alum wastewater of claim 1, which is characterized in that:
the separator further comprises a return water outlet;
and the return water outlet is connected with the first liquid inlet end of the heat exchanger.
3. The ammonium recovery and zero discharge system for titanium alum wastewater as claimed in claim 1 or 2, wherein: a pH adjusting tank or a mid-water collecting tank is provided before or after each system.
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