CN116216970A - Wastewater zero discharge system and method based on forward osmosis concentration - Google Patents

Abstract

The invention discloses a wastewater zero discharge system and a wastewater zero discharge method based on forward osmosis concentration, and relates to the technical field of salt-containing wastewater discharge, wherein the system comprises a softening pretreatment module, a multi-medium filtration module, a forward osmosis concentration module and a direct injection evaporation drying module, the softening pretreatment module is connected with the multi-medium filtration module, the multi-medium filtration module is connected with the forward osmosis concentration module, and the forward osmosis concentration module is connected with the direct injection evaporation drying module; the method comprises the following steps: adding medicine to soften the salt-containing wastewater; the pretreated wastewater is subjected to multi-medium filtration and the PH value is regulated; the wastewater is subjected to forward osmosis concentration treatment after the PH value is regulated; concentrating the waste water, directly spraying into a flue, evaporating and drying. The invention does not affect the efficiency of the boiler and occupies small area; the whole system has low running cost and low energy consumption, can recycle most of water resources, does not produce secondary pollution, and can be applied to zero discharge of waste water and recycling of waste water in industries such as thermal power, metallurgy, landfill leachate, coal chemical industry, pharmacy, mines and the like.

Description

Wastewater zero discharge system and method based on forward osmosis concentration

Technical Field

The invention relates to the technical field of salt-containing wastewater discharge, in particular to a wastewater zero discharge system and method based on forward osmosis concentration.

Background

The high-salt industrial wastewater and desulfurization wastewater contain high-concentration soluble inorganic salt, toxic and degradable organic matters, odor and the like, and the problems of environmental water pollution, air pollution and equipment scaling and corrosion are caused, so that the high-salt industrial wastewater and desulfurization wastewater become a great problem in the water treatment industry.

The method has various treatment modes and high treatment efficiency on the high-salt industrial wastewater and the desulfurization wastewater, but has a plurality of defects and defects, the technology for internationally treating the high-salt industrial wastewater mainly adopts evaporation crystallization solidification, thermal distillation, ozone catalytic oxidation method, membrane method and the like, the traditional technology such as evaporation pond technology and multi-effect evaporation technology all face the problem of difficult crystallization of final products, the mechanical evaporation crystallization technology has higher requirements on equipment material cost, the membrane method concentration has high requirements on water inlet, the easy scaling and higher energy consumption, the evaporation crystallization solidification investment is large, the heat exchange efficiency is low, the equipment is easy to corrode and scale, the energy consumption is huge, and the new technology such as membrane distillation, membrane crystallization and the like also needs further research and practice to finally achieve the zero emission of liquid.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention is to provide a wastewater zero-emission system with low operation cost, low energy consumption, capability of recycling most of water resources and no secondary pollution.

In order to achieve the above purpose, according to one aspect of the present invention, a wastewater zero discharge system based on forward osmosis concentration is provided, which comprises a softening pretreatment module, a multi-medium filtration module, a forward osmosis concentration module, and a direct injection evaporation drying module; the softening pretreatment module is connected with the multi-medium filtration module, the multi-medium filtration module is connected with the forward osmosis concentration module, and the forward osmosis concentration module is connected with the direct injection evaporation drying module;

the high-salt wastewater enters the multi-medium filtering module for filtering after being treated by the softening pretreatment module, then enters the forward osmosis concentration module for treatment, and then is sprayed into the boiler preheater after being sprayed into the boiler preheater by the flue direct-injection evaporation drying module to be evaporated by flue gas, so that zero emission of wastewater is realized.

Preferably, the softening pretreatment module comprises an adjusting tank, a dosing device, a triple box chemical reaction tank, a clarifying tank, a clean water tank, a sludge concentration tank and a sludge dehydrator;

the high-salt wastewater enters the regulating tank, then enters the triple box chemical reaction tank to react with the medicines added by the medicine adding device, and the reacted wastewater enters the clarification tank; the clarified wastewater at the upper part of the clarifier enters the clean water tank, and the wastewater containing sludge at the lower part enters the sludge concentration tank for sludge concentration; the sludge concentration tank returns supernatant after the sludge-containing wastewater treatment to the regulating tank again for treatment, and the sludge concentration tank carries out drying treatment on concentrated sludge after the sludge-containing wastewater treatment in the sludge dehydrator, and the treated dry sludge is transported to the outside for treatment.

Preferably, the triple tank chemical reaction tank comprises a neutralization tank, a reaction tank and a flocculation tank which are connected in sequence; lime milk is added into the neutralization box by the dosing device, so that the concentration of sulfate radical and heavy metal in a precipitation part are reduced; the chemical adding device adds sodium hydroxide into the reaction box to separate out Mg2+ and heavy metal ions in water; the chemical adding device adds coagulant into the flocculation tank to generate flocculate, so that the flocculate becomes larger and is easier to precipitate, solid-liquid separation of the precipitate and supernatant is realized in the clarification tank, the purposes of removing suspended matters and partially softening are achieved, and chemical sludge enters a sludge concentration and dehydration system for further treatment.

Preferably, the multi-media filtration module comprises a multi-media canister and an intermediate pond; the wastewater filtered by the multi-medium filtering tank enters an intermediate water tank, and the filtered sludge is sent to the softening pretreatment module for treatment; the intermediate water tank regulates the pH of the wastewater, and the pH of the regulated wastewater is controlled to be 6-6.5.

Preferably, the multi-media canister further removes suspended or colloidal impurities in the water using a filter of at least one of:

gravel, quartz sand, magnetite, and anthracite.

Preferably, the forward osmosis concentration module comprises a cartridge filter, a FO concentration tank, a HBCR draw solution regeneration tank and a concentrate tank; the waste water enters the FO concentration tank after passing through the cartridge filter, concentrated waste water enters the concentrated water tank, diluted HBCR (hydrogen rich CR) drawing liquid of the FO concentration tank enters the HBCR drawing liquid regeneration tank for regeneration, and the regenerated concentrated HBCR drawing liquid returns to the FO concentration tank for continuous use. The forward osmosis concentration module is divided into two systems of FO concentration and HBCR (heterojunction bipolar transistor) drawing liquid regeneration, the core of the first partial concentration system is a multi-stage FO membrane component, inlet water enters the system after pH adjustment, concentrated drawing liquid is also entered into the system, water to be treated and the drawing liquid are naturally permeated from the low-salt side to the high-salt side at two sides of the membrane where the drawing liquid is positioned, the interior is repeatedly circulated, the drawing liquid is continuously discharged after being diluted, and the water to be treated is discharged when being concentrated to a set concentration (the conductivity of the concentrated water is set to be 115mS/cm, and the TDS is set to be more than 110 g/L); the second part is an HBCR drawing liquid regeneration system, the core of the system is a second-stage high-pressure reverse osmosis membrane component, the dilute drawing liquid discharged by FO enters the second part for concentration, the concentrated liquid is the concentrated drawing liquid, the clear liquid enters the reprocessing, and finally clear water is produced, so that the purposes of wastewater concentration and clear water recycling are realized.

Preferably, the HBCR drawing liquid is a sodium chloride solution with the mass fraction of 14%.

Preferably, the direct injection evaporation drying module comprises an air compressor, a gas-liquid mixing device and a flue spray gun; the concentrated wastewater treated by the forward osmosis concentration module is mixed with compressed air from the air compressor in the gas-liquid mixing device, and the mixed wastewater is sprayed into the boiler preheater after passing through the flue spray gun and then is connected with the flue to be evaporated by flue gas.

Preferably, the direct-injection evaporation drying module further comprises an air cap, the air cap is arranged at a position, which is at a certain distance from the flue bottom to the flue spray gun, of the bottom of the flue, the air flow sprayed by the air cap can prevent wet ash from settling, the evaporation running length of atomized water drops is prolonged, and the evaporation of wastewater is promoted.

Preferably, the direct injection evaporation drying module further comprises an L-shaped columnar sleeve, the L-shaped columnar sleeve is positioned on the outer side of the flue spray gun, hot air is introduced into the sleeve, and ash accumulation on the spray gun can be reduced.

Preferably, the device also comprises a flue evaporation damping collector which is positioned in a connecting flue between the boiler air preheater and a porous plate of the boiler dust remover, the device is mainly used for preventing flue gas from entering an inlet of the electric dust remover too fast, prolonging the evaporation time of wet flue gas in the flue, and simultaneously, the device also has the function of capturing and collecting wet ash, so that the waste water is completely evaporated in the flue as much as possible, the accumulation of the wet ash in the porous plate is reduced, and ash captured by the flue evaporation damping collector enters an ash bucket at the bottom of the flue for collection treatment under the action of a rapping device.

In another aspect, the invention provides a wastewater zero-emission method based on forward osmosis concentration, which comprises the following steps:

adding medicine to soften the salt-containing wastewater;

the pretreated wastewater is subjected to multi-medium filtration and the PH value is regulated;

the wastewater is subjected to forward osmosis concentration treatment after the PH value is regulated;

concentrating the waste water, directly spraying into a flue, evaporating and drying.

Preferably, the pretreatment of adding medicine and softening the salt-containing wastewater comprises the following steps:

lime milk is added, so that the concentration of sulfate radical in the saline wastewater and the precipitated part of heavy metal are reduced;

sodium hydroxide is added to separate out Mg2+ and heavy metal ions in the salt-containing wastewater;

coagulant is added to make the flocculate generated in the salt-containing wastewater bigger and easier to precipitate.

Preferably, the pH value is adjusted to adjust the pH of the wastewater to ensure that suspended matters in the wastewater are 30-50Mg/L, the concentration of Ca2+ and Mg2+ is within the tolerance range of the forward osmosis membrane, and the pH is controlled to be 6-6.5.

Preferably, the forward osmosis concentration process comprises the steps of:

the wastewater is subjected to FO concentration after being filtered, and is discharged when the concentration is up to a set condition;

and (3) diluting the concentrated HBCR drawing liquid used for concentrating the FO, then regenerating the HBCR drawing liquid, and returning the regenerated concentrated HBCR drawing liquid to continuously concentrate the FO.

Preferably, the set condition is that the conductivity of the wastewater is 115mS/cm and the TDS is 110g/L.

Preferably, the step of directly spraying the concentrated wastewater into a flue for evaporation and drying comprises the following steps of:

the high-temperature flue gas at the outlet of the boiler air preheater is utilized to preheat the wastewater, the wastewater is pressurized and atomized by the spray gun and then sprayed into a horizontal flue between the boiler air preheater and the electric dust collector, the atomized wastewater absorbs heat in the flue and evaporates, pollutants in the wastewater are converted into solids such as crystals or salts and the like and are collected by the electric dust collector along with fly ash in the flue, and zero discharge of the wastewater is realized.

In the zero-emission system, the forward osmosis concentration system does not need complex front-end pretreatment in the operation process, the requirement on the water inflow of the system is lower than that of other systems, the TDS concentration ratio of the concentrated water of the forward concentration unit can reach 120000Mg/L, the TDS concentration ratio can reach more than 4 times, the quality of the discharged clear water completely meets the requirements of industrial circulating cooling water treatment design Specification (GB 50050-2017), the clear water can be directly used as the supplementing water of a circulating cooling water system, the concentration of Ca2+ and Mg2+ is extremely low, the hardness is basically completely eliminated, the TDS average value of the clear water is only about 280Mg/L, the desalination rate is as high as 99%, the water yield can reach 80%, and the zero-emission system runs stably; the direct-injection drying evaporation system of the flue does not need to add chemicals, utilizes waste heat of flue gas, does not influence the efficiency of the boiler, and occupies a small area; the whole zero emission system has low running cost and low energy consumption, can recycle most water resources, and does not produce secondary pollution.

The conception, specific structure, and technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, features, and effects of the present invention.

Drawings

FIG. 1 is a process route diagram of a preferred embodiment of the present invention;

fig. 2 is a flowchart of the operation of a preferred embodiment of the present invention.

Wherein:

1. a softening pretreatment module;

2. a multi-media filtration module;

3. a forward osmosis concentration module;

4. and a direct injection evaporation drying module.

Detailed Description

The following description of the preferred embodiments of the present invention refers to the accompanying drawings, which make the technical contents thereof more clear and easy to understand. The present invention may be embodied in many different forms of embodiments and the scope of the present invention is not limited to only the embodiments described herein.

In the drawings, like structural elements are referred to by like reference numerals and components having similar structure or function are referred to by like reference numerals. The dimensions and thickness of each component shown in the drawings are arbitrarily shown, and the present invention is not limited to the dimensions and thickness of each component. The thickness of the components is exaggerated in some places in the drawings for clarity of illustration.

As shown in fig. 1, the preferred embodiment provides a wastewater zero discharge system based on forward osmosis concentration, which comprises a softening pretreatment module 1, a multi-medium filtration module 2, a forward osmosis concentration module 3 and a direct injection evaporation drying module 4; the softening pretreatment module 1 is connected with the multi-medium filtration module 2, the multi-medium filtration module 2 is connected with the forward osmosis concentration module 3, and the forward osmosis concentration module 3 is connected with the direct injection evaporation drying module 4; the high-salt wastewater enters a multi-medium filtering module 2 for filtering after being treated by a softening pretreatment module 1, then enters a forward osmosis concentration module 3 for treatment, and is sprayed into a boiler preheater after being directly sprayed by a flue direct-injection evaporation drying module 4 and then is evaporated by flue gas in a connecting flue, so that zero emission of wastewater is realized.

The softening pretreatment module 1 comprises an adjusting tank, a dosing device, a triple box chemical reaction tank, a clarifying tank, a clean water tank, a sludge concentration tank and a sludge dewatering machine, and further comprises related instrument valve connecting pipelines;

the high-salt wastewater enters an adjusting tank, then enters a triple box chemical reaction tank to react with the medicines added by the medicine adding device, and the reacted wastewater enters a clarification tank; the upper clarified wastewater of the clarifier enters a clean water tank, and the lower sludge-containing wastewater enters a sludge concentration tank for sludge concentration; the sludge concentration tank returns supernatant fluid after the sludge-containing wastewater treatment to the regulating tank again for treatment, and the sludge concentration tank carries out drying treatment on concentrated sludge after the sludge-containing wastewater treatment in the sludge dehydrator, and the treated dry sludge is transported to the outside for treatment.

The three-header chemical reaction tank comprises a neutralization tank, a reaction tank and a flocculation tank which are connected in sequence; lime milk is added into the neutralization box by the dosing device, so that the concentration of sulfate radical and heavy metal in a precipitation part are reduced; the chemical adding device adds sodium hydroxide into the reaction box to separate out Mg2+ and heavy metal ions in the water; the medicine adding device adds coagulant into the flocculation tank to generate flocculate, so that the flocculate becomes larger and is easier to precipitate, solid-liquid separation of the precipitate and supernatant is realized in the clarification tank, the purposes of removing suspended matters and partially softening are achieved, and chemical sludge enters a sludge concentration tank and a sludge dewatering machine for further treatment.

In the preferred implementation, the sludge dewatering machine adopts a plate-and-frame filter press, and has the advantages of large filtering driving force, high solid content of filter cakes, clear filtrate, high solid recovery rate, small consumption of conditioning medicines and the like.

The multi-medium filter module 2 comprises a multi-medium filter tank and an intermediate water tank; in addition, the utility model also comprises a water inlet pump, a flushing water pump and related instrument valve connecting pipelines; the wastewater filtered by the multi-medium filter tank enters an intermediate water tank, and the filtered sludge is sent to a softening pretreatment module 1 for treatment; the pH of the wastewater is regulated by the middle water tank and is controlled to be 6-6.5 after the regulation.

The multi-medium filter tank adopts at least one of the following filter materials to further remove suspended or colloidal impurities in water:

gravel, quartz sand, magnetite, anthracite and other filter materials.

TABLE 1 quality of desulfurization wastewater after softening and filtration in certain Power plant

The forward osmosis concentration module 3 comprises a cartridge filter, an FO concentration tank, an HBCR drawing liquid regeneration tank and a concentrated water tank, and also comprises relevant instrument valve connecting pipelines such as a booster water pump, a recovery water tank and the like; the FO concentration tank comprises a forward osmosis membrane component, a back washing system and the like; the wastewater enters an FO concentration tank after passing through a cartridge filter, concentrated wastewater enters a concentrated water tank, diluted HBCR (hydrogen rich CR) drawing liquid of the FO concentration tank is diluted, the diluted HBCR drawing liquid enters an HBCR drawing liquid regeneration tank for regeneration, and the regenerated concentrated HBCR drawing liquid returns to the FO concentration tank for continuous use. The forward osmosis concentration module 3 is divided into two systems of FO concentration and HBCR (heterojunction bipolar transistor) drawing liquid regeneration, the core of the first partial concentration system is a multi-stage FO membrane component, inlet water enters the system after pH adjustment, concentrated drawing liquid is also entered into the system, water to be treated and the drawing liquid are respectively positioned at two sides of a membrane, the water naturally permeates from a low-salt side to a high-salt side, the inside is circulated repeatedly, the drawing liquid is continuously discharged after being diluted, and the water to be treated is discharged when being concentrated to a set concentration (the conductivity of the concentrated water is set to be 115mS/cm, and the TDS is set to be more than 110 g/L); the second part is an HBCR drawing liquid regeneration system, the core of the system is a second-stage high-pressure reverse osmosis membrane component, the dilute drawing liquid discharged by FO enters the second part for concentration, the concentrated liquid is the concentrated drawing liquid, the clear liquid enters the reprocessing, and finally clear water is produced, so that the purposes of wastewater concentration and clear water recycling are realized. The forward osmosis system can concentrate desulfurization wastewater of a power plant with inflow TDS of 12000 Mg/L-16000 Mg/L to about 100000 ～ 120000Mg/L, the concentration ratio of the TDS can reach more than 8-10, the requirement of zero-discharge treatment concentration decrement of the desulfurization wastewater can be basically met, the forward osmosis system can be used as a front-end working section of bypass flue evaporation or other heat treatment, the quality of produced water can completely meet the requirement of industrial circulating cooling water treatment design Specification (GB 50050-2017), the forward osmosis system can be directly used as the supplementing water of a circulating cooling water system, the concentration of Ca2+ and Mg2+ is extremely low, the hardness is basically completely eliminated, the TDS average value of clear water is only about 200Mg/L, the desalination rate is up to 98%, and the water yield can reach 90%.

The HBCR drawing liquid is sodium chloride solution with the mass fraction of 14%.

TABLE 2 Forward osmosis Membrane produced Water quality parameters

The direct injection evaporation drying module 4 comprises an air compressor, a gas-liquid mixing device and a flue spray gun; the concentrated wastewater treated by the forward osmosis concentration module 3 is mixed with compressed air from an air compressor in a gas-liquid mixing device, and is sprayed into a boiler preheater through a flue spray gun and then is connected with a flue to be evaporated by flue gas.

The direct-injection evaporation drying module 4 further comprises an air cap, the air cap is arranged at a position, which is at a certain distance from the flue spray gun, of the bottom of the flue, the air flow sprayed by the air cap can prevent wet ash from settling, the evaporation running length of atomized water drops is prolonged, and the evaporation of wastewater is promoted.

The direct injection evaporation drying module 4 further comprises an L-shaped columnar sleeve, the L-shaped columnar sleeve is positioned at the outer side of the flue spray gun, hot air is introduced into the sleeve, and dust accumulation on the spray gun can be reduced.

The device is mainly used for preventing flue gas from entering an inlet of the electric dust collector too quickly, prolonging the evaporation time of wet flue gas in the flue, and simultaneously, the device also has the function of capturing and collecting wet ash, so that the waste water is completely evaporated in the flue as much as possible, the accumulation of the wet ash in the porous plate is reduced, and ash captured by the flue evaporation damping collector enters an ash bucket at the bottom of the flue to be collected under the action of a vibrating device.

As shown in fig. 2, the present embodiment provides a wastewater zero-discharge method based on forward osmosis concentration for use with a wastewater zero-discharge system based on forward osmosis concentration, which includes the following steps:

(1) Wastewater softening pretreatment

Adding medicine to soften the salt-containing wastewater;

lime milk is added, so that the concentration of sulfate radical in the saline wastewater and the precipitated part of heavy metal are reduced; sodium hydroxide is added to separate out Mg2+ and heavy metal ions in the salt-containing wastewater; coagulant is added to make the flocculate generated in the salt-containing wastewater bigger and easier to precipitate.

(2) Multi-media filtration

The pretreated wastewater is subjected to multi-medium filtration and the PH value is regulated;

filtering materials such as gravel, quartz sand, magnetite, anthracite and the like are utilized to remove suspended or colloidal impurities in water, HCl is added to adjust the pH of the wastewater, so that the suspended matters in the wastewater are 30-50Mg/L, the concentration of Ca2+ and Mg2+ is within the tolerance range of a forward osmosis membrane, and the pH is controlled to be 6-6.5.

(3) Forward osmosis concentration

The wastewater is subjected to forward osmosis concentration treatment after the PH value is regulated; the wastewater is subjected to FO concentration after being filtered, and is discharged when the concentration is up to a set condition; and (3) diluting the concentrated HBCR drawing liquid used for concentrating the FO, then regenerating the HBCR drawing liquid, and returning the regenerated concentrated HBCR drawing liquid to continuously concentrate the FO.

The FO concentration was set at a wastewater conductivity of 115mS/cm and a TDS of 110g/L.

(4) Direct injection evaporative drying

Concentrated waste water is directly sprayed into a flue for evaporation and drying, high-temperature flue gas at the outlet of the boiler air preheater is utilized for preheating, the waste water is sprayed into a horizontal flue between the boiler air preheater and the electric dust collector after being pressurized and atomized by a spray gun, the atomized waste water absorbs heat in the flue for evaporation, pollutants in the waste water are converted into solids such as crystals or salts and the like, and the solids are collected by the electric dust collector along with fly ash in the flue, so that zero emission of the waste water is realized.

In the zero-emission system, the forward osmosis concentration system does not need complex front-end pretreatment in the operation process, the requirement on the water inflow of the system is lower than that of other systems, the TDS concentration ratio of the concentrated water of the forward concentration unit can reach 120000Mg/L, the TDS concentration ratio can reach more than 4 times, the quality of the discharged clear water completely meets the requirements of industrial circulating cooling water treatment design Specification (GB 50050-2017), the clear water can be directly used as the supplementing water of a circulating cooling water system, the concentration of Ca2+ and Mg2+ is extremely low, the hardness is basically completely eliminated, the TDS average value of the clear water is only about 280Mg/L, the desalination rate is as high as 99%, the water yield can reach 80%, and the zero-emission system runs stably; the direct-injection drying evaporation system of the flue does not need to add chemicals, utilizes waste heat of flue gas, does not influence the efficiency of the boiler, and occupies a small area; the whole zero emission system has low running cost and low energy consumption, can recycle most water resources, and does not produce secondary pollution.

The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention without requiring creative effort by one of ordinary skill in the art. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.

Claims (17)

1. The wastewater zero discharge system based on forward osmosis concentration is characterized by comprising a softening pretreatment module, a multi-medium filtering module, a forward osmosis concentration module and a direct injection evaporation drying module; the softening pretreatment module is connected with the multi-medium filtration module, the multi-medium filtration module is connected with the forward osmosis concentration module, and the forward osmosis concentration module is connected with the direct injection evaporation drying module;

the high-salt wastewater enters the multi-medium filtering module for filtering after being treated by the softening pretreatment module, then enters the forward osmosis concentration module for treatment, and then is sprayed into the boiler preheater after passing through the direct injection evaporation drying module and then is evaporated by flue gas in a connecting flue, so that zero emission of wastewater is realized.

2. The wastewater zero discharge system based on forward osmosis concentration of claim 1, wherein the softening pretreatment module comprises an adjusting tank, a dosing device, a triple tank chemical reaction tank, a clarifier, a clean water tank, a sludge concentration tank and a sludge dewatering machine;

the high-salt wastewater enters the regulating tank, then enters the triple box chemical reaction tank to react with the medicines added by the medicine adding device, and the reacted wastewater enters the clarification tank; the clarified wastewater at the upper part of the clarifier enters the clean water tank, and the wastewater containing sludge at the lower part enters the sludge concentration tank for sludge concentration; the sludge concentration tank returns supernatant after the sludge-containing wastewater treatment to the regulating tank again for treatment, and the sludge concentration tank carries out drying treatment on concentrated sludge after the sludge-containing wastewater treatment in the sludge dehydrator, and the treated dry sludge is transported to the outside for treatment.

3. The wastewater zero discharge system based on forward osmosis concentration according to claim 2, wherein the triple tank chemical reaction tank comprises a neutralization tank, a reaction tank and a flocculation tank which are connected in sequence; the dosing device adds lime milk in the neutralization box; the chemical adding device adds sodium hydroxide into the reaction box; the coagulant is added into the flocculation tank by the dosing device.

4. The zero wastewater discharge system based on forward osmosis concentration of claim 1, wherein the multi-media filtration module comprises a multi-media canister and an intermediate basin; the wastewater filtered by the multi-medium filtering tank enters an intermediate water tank, and the filtered sludge is sent to the softening pretreatment module for treatment; the intermediate water tank regulates the pH of the wastewater, and the pH of the regulated wastewater is controlled to be 6-6.5.

5. The zero wastewater discharge system based on forward osmosis concentration of claim 4, wherein the multi-media canister is a filter of at least one of:

gravel, quartz sand, magnetite, and anthracite.

6. The forward osmosis concentration based wastewater zero release system of claim 1 wherein the forward osmosis concentration module comprises a cartridge filter, a FO concentration tank, an HBCR draw solution regeneration tank, and a concentrate tank; the waste water enters the FO concentration tank after passing through the cartridge filter, concentrated waste water enters the concentrated water tank, diluted HBCR (hydrogen rich CR) drawing liquid of the FO concentration tank enters the HBCR drawing liquid regeneration tank for regeneration, and the regenerated concentrated HBCR drawing liquid returns to the FO concentration tank for continuous use.

7. The wastewater zero discharge system based on forward osmosis concentration according to claim 6, wherein the HBCR drawing solution is a sodium chloride solution with a mass fraction of 14%.

8. The wastewater zero discharge system based on forward osmosis concentration according to claim 1, wherein the direct injection evaporative drying module comprises an air compressor, a gas-liquid mixing device and a flue gun; the concentrated wastewater treated by the forward osmosis concentration module is mixed with compressed air from the air compressor in the gas-liquid mixing device, and the mixed wastewater is sprayed into the boiler preheater after passing through the flue spray gun and then is connected with the flue to be evaporated by flue gas.

9. The zero wastewater discharge system based on forward osmosis concentration of claim 8, wherein the direct injection evaporative drying module further comprises an air cap mounted at a distance from the flue lance at the bottom of the flue, the air stream sprayed by the air cap preventing the settling of wet ash.

10. The forward osmosis concentration based wastewater zero release system of claim 8 wherein the direct injection evaporative drying module further comprises an L-shaped cylindrical sleeve positioned outside of the flue lance.

11. The wastewater zero discharge system based on forward osmosis concentration as claimed in claim 1, further comprising a flue evaporation damping collector, wherein the flue evaporation damping collector is positioned in a connecting flue between the boiler air preheater and a perforated plate of the boiler dust remover, and ash captured by the flue evaporation damping collector enters an ash bucket at the bottom of the flue for collection treatment under the action of a rapping device.

12. A wastewater zero discharge method based on forward osmosis concentration, which is characterized by comprising the following steps:

adding medicine to soften the salt-containing wastewater;

the pretreated wastewater is subjected to multi-medium filtration and the PH value is regulated;

the wastewater is subjected to forward osmosis concentration treatment after the PH value is regulated;

concentrating the waste water, directly spraying into a flue, evaporating and drying.

13. The method of claim 12, wherein the pre-treatment of the saline wastewater with a medicated softener comprises the steps of:

lime milk is added, so that the concentration of sulfate radical in the saline wastewater and the precipitated part of heavy metal are reduced;

adding sodium hydroxide to enable Mg in the salt-containing wastewater ²⁺ And heavy metal ions are separated out;

coagulant is added to make the flocculate generated in the salt-containing wastewater bigger and easier to precipitate.

14. The method of claim 12, wherein the pH is adjusted to adjust the pH of the wastewater to a wastewater suspension of 30-50mg/L, ca ²⁺ 、Mg ²⁺ The concentration is within the tolerance range of the forward osmosis membrane, and the pH is controlled between 6 and 6.5.

15. The method of claim 12, wherein the forward osmosis concentration process comprises the steps of:

the wastewater is subjected to FO concentration after being filtered, and is discharged when the concentration is up to a set condition;

and (3) diluting the concentrated HBCR drawing liquid used for concentrating the FO, then regenerating the HBCR drawing liquid, and returning the regenerated concentrated HBCR drawing liquid to continuously concentrate the FO.

16. The method of claim 15, wherein the set condition is wastewater conductivity of 115mS/cm and TDS of 110g/L.

17. The method of claim 12, wherein the step of direct injection of concentrated wastewater into the flue for evaporative drying comprises:

the high-temperature flue gas at the outlet of the boiler air preheater is utilized to preheat the wastewater, the wastewater is pressurized and atomized by the spray gun and then sprayed into a horizontal flue between the boiler air preheater and the electric dust collector, the atomized wastewater absorbs heat in the flue and evaporates, pollutants in the wastewater are converted into solids such as crystals or salts and the like and are collected by the electric dust collector along with fly ash in the flue, and zero discharge of the wastewater is realized.

Images