Method for treating high-sodium, high-chlorine and organic-matter-rich coal elution wastewater by using biological enzyme

Abstract

The invention provides a method for treating high-sodium, high-chlorine and organic-matter-rich coal elution wastewater by using biological enzyme, which comprises the following steps: preparing coal elution wastewater in an elution reactor by using weakly acidic desalted water and Xinjiang Zhundong coal, homogenizing the wastewater in an adjusting tank, and feeding the wastewater to an integrated efficient precipitation system for dosing flocculation precipitation, the method comprises the following steps: feeding coal into an integrated AO + MBR system, feeding a compound biological enzyme into the AO system, carrying out a biodegradation reaction, removing organic matters, ammonia nitrogen and suspended matters in the coal elution wastewater through the MBR system after degradation is completed, pumping produced water into a reverse osmosis system after passing through a security filter, and removing impurities such as dissolved salts and organic matters in the water. According to a traditional mode, an oxidizing agent is added for degradation, new inorganic salt can be introduced by adding the oxidizing agent, so that the load of a membrane system is increased, the inorganic salt cannot be introduced into the coal elution wastewater by utilizing the biological enzyme for treatment, and no side effect is generated on a subsequent membrane treatment system.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a method for treating coal leaching wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes. Background Art

[0002] The predicted coal reserves in Xinjiang are 2.19 trillion tons, accounting for more than 40% of the national predicted coal reserves. Among them, the Zhundong Coalfield in Xinjiang is the largest integrated coalfield in China at present, with a proven reserve of 390 billion tons, and the predicted reserve of the Turpan-Hami Coalfield is 570 billion tons. However, the coal quality of these two major coalfields has the characteristics of high sodium and high chlorine. For example, the sodium content in Zhundong coal is as high as more than 6% (ash basis), and the chlorine content in some coal in the Turpan-Hami Coal Mine is as high as 1% (coal basis), both of which are more than 5 times higher than that of ordinary coal. This brings serious slagging fouling and corrosion problems to coal-fired boilers and coal gasifiers. To solve the problems of slagging fouling and corrosion of high-sodium and high-chlorine coal from the source, washing the coal to remove sodium and chlorine is one of the effective ways.

[0003] The coal washing technology has a simple process, is technically mature, and has a low cost, and has developed rapidly in China in recent years. However, the traditional coal washing technology has insufficient removal effects on sodium and chlorine, and the removal rate is below 50%. It cannot remove organic minerals in coal (such as carboxylates), water-insoluble inorganic minerals (such as calcium carbonate), and inorganic salts coated by coal particles or mineral particles. And the coal in Xinjiang just has the characteristics of high content of organic minerals and water-insoluble inorganic minerals. In addition, the coal quality in Xinjiang is relatively young, and the content of high-molecular humic acid and organic matter is higher compared with coal types in other regions. Therefore, the washing wastewater of the above coal types has a relatively high content of high-molecular organic matter, such as active groups such as carboxyl, aldehyde and various amino acids. These organic matters will have a serious impact on the deionization treatment of the wastewater, form organic fouling of the membrane, greatly increase the frequency of backwashing, and reduce the service life of the membrane. Therefore, the commonly used method for removing organic pollutants is to add flocculants for flocculation sedimentation separation at the end of biochemical treatment, but the operating cost is high, and the added flocculants still need to be separated from the water, which greatly increases the load of membrane treatment. Therefore, how to efficiently reduce the sodium and chlorine content in Zhundong coal in Xinjiang and treat the wastewater of coal rich in organic matter is an urgent problem to be solved. Summary of the Invention

[0004] To solve the above problems, the present invention provides a method for treating coal leaching wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes, which uses coal leaching to efficiently reduce the sodium and chlorine content in coal, and uses bioenzymes to treat the coal leaching wastewater, so as to achieve the purpose of upgrading and utilization of Zhundong coal in Xinjiang.

[0005] The technical solution of the present invention is as follows: A method for treating coal leaching wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes, comprising the following steps: Step 1: The raw coal is crushed into coal particles with a diameter of 3 mm to 10 mm. The coal particles are lifted to the precipitation reactor by a feeding pump and mixed with the precipitation solution. The precipitation solution is weakly acidic desalted water with a pH value controlled at 3.0 to 4.0 and a temperature controlled at 20 to 35 °C. The reaction residence time is controlled at 60 min to 100 min. After precipitation, the coal particles enter a dehydration screen and a plate and frame filter press from the reactor outlet for dehydration, generating coal precipitation wastewater. When the TDS in the coal precipitation wastewater is greater than 10,000 mg / L, it is discharged from the precipitation reactor into the first regulation tank, and at the same time, the precipitation solution is replenished into the precipitation reactor. Step 2: The coal precipitation wastewater is homogenized and equalized in the regulation tank. After the wastewater in the regulation tank reaches a certain volume, it is lifted to the integrated high-efficiency precipitation system by a pump. The integrated high-efficiency precipitation system is provided with a lime dosing area, a flocculation area, and a precipitation area. The pH value in the lime dosing area is controlled at 9.5 to 11, the temperature is controlled at 25 to 40 °C, and the reaction residence time is controlled at 20 min to 40 min. In the lime dosing area, sodium carbonate and calcium hydroxide are added to react the bicarbonate in the coal precipitation wastewater with lime to form calcium carbonate. At the same time, the excess calcium ions react with the added sodium carbonate to form calcium carbonate, and then enter the flocculation area. The colloids and suspended substances in the coal precipitation wastewater are intensively flocculated under the combined action of a polymer organic flocculant and recycled sludge to form high-density flocs, which are co-precipitated at room temperature in the precipitation area for 10 hours and concentrated to form concentrated sludge. Part of the concentrated sludge is recycled to the flocculation area, and part is regularly discharged externally. The supernatant further removes fine particulate matter through an inclined tube and enters the integrated AO + MBR system. Step 3: The temperature in the AO system is controlled at 25 to 35 °C, and the pH value is controlled at 7.0 to 8.0. A composite bio-enzyme is added to the AO system. The composite bio-enzyme includes: a main enzyme and a composite coenzyme. The main enzyme includes a non-soluble organic matter catalytic enzyme, a microbial salt tolerance enzyme, a soluble oil catalytic enzyme, a surfactant catalytic enzyme, a heterocyclic organic matter catalytic protease, and a humic acid catalytic enzyme. The composite coenzyme includes a microbial carrier enzyme G, a microbial carrier enzyme F, a microbial carrier enzyme GC, and a microbial carrier enzyme P. The dosage of the main enzyme is 3 g to 5 g per ton of water, and the dosage of the composite coenzyme is 15 g to 20 g per ton of water. The dissolution water temperature of the main enzyme and the composite coenzyme is controlled at 20 to 30 °C, and the dissolution time is controlled at 18 to 24 hours. The reaction time is 36 hours. The unreacted polymer organic flocculant in Step 2 is degraded in the integrated AO + MBR system. After the reaction is completed, the organic matter, ammonia nitrogen, and suspended substances in the coal precipitation wastewater are removed through the MBR system. Through the establishment and maintenance of the enzyme system during the operation process of the enzyme system, it is ensured that the AO system can efficiently treat the precipitation wastewater and at the same time maintain the salt tolerance of microorganisms. Step 4: The water produced by the integrated AO + MBR system is pumped into the reverse osmosis system through a security filter to remove impurities such as dissolved salts and organic matter in the water. The deionized water produced by the reverse osmosis system enters the product water tank, and the concentrated brine enters the electrodialysis system. Step 5: After passing through the electrodialysis system, the concentrated brine is separated into fresh water and extreme liquid through an ion membrane. The extreme liquid enters the multi-effect evaporation system, and the TDS can reach 150,000 mg / L. The fresh water is mixed with the MBR effluent and then recycled into the reverse osmosis system for desalination. Step 6: The extreme liquid is collected and enters the multi-effect evaporation system. After multi-effect evaporation, the extreme liquid crystallizes into salt, and the condensate enters the product water tank. The water in the product water tank is used as makeup water for the dissolution and precipitation reactor and enters the system again.

[0006] Further, the polymer organic flocculant is PAM anionic polyacrylamide.

[0007] The beneficial effects of the present invention are as follows.

[0008] 1. A method for treating coal dissolution wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes uses bioenzymes to cooperate in degrading refractory organic matter and improving the salt tolerance of microorganisms, increasing the concentration multiple of coal dissolution wastewater by more than one time, reducing the construction scale of the biochemical system and the membrane system, reducing the floor area of factory buildings and equipment facilities, and reducing the investment cost.

[0009] 2. A method for treating coal dissolution wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes uses bioenzymes to degrade refractory organic pollutants in coal dissolution wastewater. In the traditional method, oxidants are added for degradation, and the addition of oxidants will introduce new inorganic salts, increasing the load on the membrane system. The method of the present invention using bioenzymes for treatment will not introduce inorganic salts into the coal dissolution wastewater, will not cause any side effects to the subsequent membrane treatment system, will not cause secondary pollution of chemical sludge, and conforms to industrial policies and modern water treatment concepts.

[0010] 3. A method for treating coal dissolution wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes, due to the introduction of specific bioenzymes, greatly reduces the generation of foam in the biochemical tank, without secondary pollution and without the generation of a large amount of sludge.

[0011] 4. A method for treating coal dissolution wastewater with high sodium, high chlorine and rich in organic matter uses the CO2-rich coking combustion chamber waste gas or the CO2-rich waste gas from coal chemical industry as the CO2 acid source to prepare a slightly acidic dissolution and precipitation solution to efficiently remove substances such as sodium and chlorine in coal. With the assistance of bioenzymes, the ash removal rate of coal can reach 30%, the sodium removal rate can reach 85%, and the chlorine removal rate can reach 85% under normal temperature and pressure, which is more than 20% higher than that of alkali metals and chloride ions through ordinary coal washing technology. Description of the Drawings

[0012] Figure 1 Flow chart of a method for treating coal leaching wastewater with high sodium, high chlorine and rich in organic matter by using bioenzymes according to the present invention Specific implementation manners

[0013] In order to make the implementation purpose, technical solution and advantages of the present invention clearer and more distinct. The technical solutions implemented in the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention. Other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts all fall within the scope of protection of the present invention.

[0014] The specific implementation manners of the present invention will be further described in detail below with reference to the accompanying drawings.

[0015] As Figure 1 shown, the implementation steps of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention. Example 1

[0016] A method for treating coal leaching wastewater with high sodium, high chlorine and rich in organic matter provided by the present invention: Take the raw coal from a certain coalfield in Zhundong, Xinjiang and crush it into coal particles with a diameter of 3 mm to 10 mm. Lift the coal particles to a leaching reactor through a feeding pump and react with weakly acidic desalted water with a pH value controlled at 3.0 to 4.0 and a temperature controlled at 20 to 35 °C for 60 min. After multiple reactions of the leaching solution, when the TDS in the coal leaching wastewater is greater than 1000 mg / L, discharge it from the leaching reactor into the regulation tank; The coal leaching wastewater is lifted to an integrated high-efficiency precipitation system through a pump after being homogenized and equalized in the regulation tank. Control the pH value of the coal leaching wastewater at 9.5 to 11 and the temperature at 25 to 40 °C in the lime dosing area of the integrated high-efficiency precipitation system and react for 20 min, then enter the flocculation area. Add PAM anionic polyacrylamide in the flocculation area to flocculate the colloid and suspended matter in the coal leaching wastewater to form high-density flocs, and then co-precipitate at room temperature in the precipitation area for 10 hours and concentrate to form concentrated sludge. The supernatant enters the integrated AO + MBR system; The temperature of the AO system is controlled at 25 - 35°C, and the pH value is controlled at 7.0 - 8.0. A composite bio - enzyme is added to the AO system. The main enzymes, namely non - soluble organic matter catalyzing enzyme, microbial salt - tolerance enzyme, soluble oil - catalyzing enzyme, surfactant - catalyzing enzyme, heterocyclic organic matter - catalyzing protease, and humic acid - catalyzing enzyme, are configured in a ratio of 1:1:1:1:1:1. The composite coenzymes, namely microbial carrier enzyme G, microbial carrier enzyme F, microbial carrier enzyme GC, and microbial carrier enzyme P, are configured in a ratio of 1:1:1:1. The total dosage of the main enzyme is 3 g per ton of water, and the total dosage of the composite coenzyme is 15 g per ton of water. The dissolution water temperature of the main enzyme and the composite coenzyme is controlled at 20 - 30°C. The dissolution time of the bio - enzyme is 18 hours, and the reaction time after being added to the wastewater is 36 hours. After degradation is completed, the organic matter, ammonia nitrogen, and suspended solids in the coal leaching wastewater are removed through the MBR system; The water produced by the integrated AO + MBR system is pumped into the reverse osmosis system through a security filter to remove impurities such as dissolved salts and organic matter in the water. The deionized water produced by the reverse osmosis system enters the water production pool, and the concentrated brine enters the electrodialysis system. The concentrated brine is separated into fresh water and extreme liquid through an ion membrane. The TDS of the extreme liquid can reach 150000 mg / L. Among them, the extreme liquid enters the multi - effect evaporation system, and after multi - effect evaporation, the extreme liquid crystallizes into salt. The fresh water is mixed with the MBR effluent and then recycled into the reverse osmosis system for desalination; The reverse osmosis produced water and the multi - effect evaporation condensate enter the water production pool and are used as supplementary water for the leaching reactor and then enter the system again.

[0017] The water quality data before and after wastewater treatment are shown in the following table.

[0018] Item Before treatment After treatment Unit pH 7.0-8.5 7.0-8.5 / CODCr ≤200 ≤50 mg / L SS ≤900 ≤10 mg / L TDS ≤8000 ≤1000 mg / L K+ ≤150 ≤100 mg / L Ca2+ ≤1000 ≤50 mg / L Mg2+ ≤350 ≤50 mg / L SO42- ≤1700 ≤300 mg / L Cl- ≤5000 ≤250 mg / L Example 2

[0019] A method for treating coal leaching wastewater with high sodium, high chlorine, and rich in organic matter using bio - enzyme provided by the present invention: The preparation process of the coal leaching wastewater is the same as that in Example 1. The coal leaching wastewater is homogenized and equalized in the regulating tank and then lifted to the integrated high - efficiency precipitation system by a pump. In the lime dosing area of the integrated high - efficiency precipitation system, the pH value of the coal leaching wastewater is controlled at 9.5 - 11, the temperature is controlled at 25 - 40°C, and the reaction lasts for 30 min. Then it enters the flocculation area. In the flocculation area, PAM anionic polyacrylamide is added to make the colloids and suspended solids in the coal leaching wastewater flocculate to form high - density flocs. Then, at room temperature, it co - precipitates in the precipitation area for 10 hours and is concentrated to form concentrated sludge. The supernatant enters the integrated AO + MBR system; The temperature of the AO system is controlled at 25 - 35°C, and the pH value is controlled at 7.0 - 8.0. A composite bio-enzyme is added to the AO system. The main enzymes, namely non-soluble organic matter catalytic enzyme, microbial salt-tolerant enzyme, soluble oil catalytic enzyme, surfactant catalytic enzyme, heterocyclic organic matter catalytic protease, and humic acid catalytic enzyme, are configured in a ratio of 1:1:1:1:1:1. The composite coenzymes, namely microbial carrier enzyme G, microbial carrier enzyme F, microbial carrier enzyme GC, and microbial carrier enzyme P, are configured in a ratio of 1:1:1:1. The total dosage of the main enzymes is 5 g per ton of water, and the total dosage of the composite coenzymes is 20 g per ton of water. The dissolution water temperature of the main enzymes and composite coenzymes is controlled at 20 - 30°C. The dissolution time of the bio-enzyme is 18 hours, and the reaction time after being added to the wastewater is 36 hours. After degradation is completed, the organic matter, ammonia nitrogen, and suspended solids in the coal leaching wastewater are removed through the MBR system; The water produced by the integrated AO + MBR system is pumped into the reverse osmosis system through a security filter to remove impurities such as dissolved salts and organic matter in the water. The deionized water produced by the reverse osmosis system enters the product water tank, and the concentrated brine enters the electrodialysis system. The concentrated brine is separated into fresh water and extreme liquid through the ion membrane. The TDS of the extreme liquid is 150,000 mg / L. Among them, the extreme liquid enters the multi-effect evaporation system and crystallizes into salt after multi-effect evaporation. The fresh water is mixed with the MBR effluent and recycled into the reverse osmosis system for desalination; The reverse osmosis product water and the multi-effect evaporation condensate enter the product water tank and are used as the makeup water for the leaching reactor and then enter the system again.

[0020] The water quality data before and after wastewater treatment are shown in the following table.

[0021] Item Before treatment After treatment Unit pH 7.0-8.5 7.0-8.5 / CODCr ≤250 ≤50 mg / L SS ≤1000 ≤10 mg / L TDS ≤9000 ≤1000 mg / L K+ ≤150 ≤100 mg / L Ca2+ ≤1000 ≤50 mg / L Mg2+ ≤350 ≤50 mg / L SO42- ≤1700 ≤300 mg / L Cl- ≤5500 ≤200 mg / L Example 3

[0022] A method for treating coal leaching wastewater with high sodium, high chlorine, and rich in organic matter using bio-enzyme provided by the present invention: The preparation process of the coal leaching wastewater is the same as that in Example 1. The coal leaching wastewater is homogenized and equalized in the regulating tank and then lifted to the integrated high-efficiency precipitation system by a pump. In the lime dosing area of the integrated high-efficiency precipitation system, the pH value of the coal leaching wastewater is controlled at 9.5 - 11, and the temperature is controlled at 25 - 40°C for reaction for 20 min, and then enters the flocculation area. In the flocculation area, PAM anionic polyacrylamide is added to make the colloids and suspended solids in the coal leaching wastewater flocculate to form high-density flocs, and then co-precipitate at room temperature in the precipitation area for 10 hours and concentrate to form concentrated sludge. The supernatant enters the integrated AO + MBR system; The temperature of the AO system is controlled at 25 - 35°C, and the pH value is controlled at 7.0 - 8.0. A composite bio - enzyme is added to the AO system. The main enzymes, namely non - soluble organic matter catalyzing enzyme, microbial salt - tolerance enzyme, soluble oil - catalyzing enzyme, surfactant - catalyzing enzyme, heterocyclic organic matter catalyzing protease, and humic acid - catalyzing enzyme, are configured in a ratio of 1:2:2:1:1:2. The composite coenzymes, namely microbial carrier enzyme G, microbial carrier enzyme F, microbial carrier enzyme GC, and microbial carrier enzyme P, are configured in a ratio of 1:1:1:1. The total dosage of the main enzyme is 3 g per ton of water, and the total dosage of the composite coenzyme is 15 g per ton of water. The dissolution water temperature of the main enzyme and the composite coenzyme is controlled at 20 - 30°C. The dissolution time of the bio - enzyme is 18 hours, and the reaction time after adding it to the wastewater is 36 hours. After degradation is completed, the organic matter, ammonia nitrogen, and suspended solids in the coal leaching wastewater are removed through the MBR system; The water produced by the integrated AO + MBR system is pumped into the reverse osmosis system through a security filter to remove impurities such as dissolved salts and organic matter in the water. The deionized water produced by the reverse osmosis system enters the product water tank, and the concentrated brine enters the electrodialysis system. The concentrated brine is separated into fresh water and extreme liquid through the ion membrane. The TDS of the extreme liquid can reach 150000 mg / L. Among them, the extreme liquid enters the multi - effect evaporation system, and after multi - effect evaporation, the extreme liquid crystallizes into salt. The fresh water is mixed with the MBR effluent and then recycled into the reverse osmosis system for desalination; The reverse osmosis product water and the multi - effect evaporation condensate enter the product water tank as the makeup water for the leaching reactor and then enter the system again.

[0023] The water quality data before and after wastewater treatment are shown in the following table.

[0024] Item Before treatment After treatment Unit pH 7.0-8.5 7.0-8.5 / CODCr ≤300 ≤50 mg / L SS ≤900 ≤10 mg / L TDS ≤10000 ≤900 mg / L K+ ≤150 ≤100 mg / L Ca2+ ≤1100 ≤50 mg / L Mg2+ ≤350 ≤50 mg / L SO42- ≤1700 ≤300 mg / L Cl- ≤6000 ≤200 mg / L Example 4

[0025] A method for treating coal leaching wastewater with high sodium, high chlorine, and rich in organic matter using bio - enzyme provided by the present invention: The preparation process of the coal leaching wastewater is the same as that in Example 1. The coal leaching wastewater is homogenized and equalized in the regulating tank and then pumped to the integrated high - efficiency precipitation system through a pump. In the lime dosing area of the integrated high - efficiency precipitation system, the pH value of the coal leaching wastewater is controlled at 9.5 - 11, and the temperature is controlled at 25 - 40°C for 20 min. Then it enters the flocculation area, and PAM anionic polyacrylamide is added in the flocculation area to make the colloids and suspended solids in the coal leaching wastewater flocculate to form high - density flocs. Then it undergoes co - precipitation at room temperature in the precipitation area for 10 hours and is concentrated to form concentrated sludge. The supernatant enters the integrated AO + MBR system; The temperature of the AO system is controlled at 25 - 35°C, and the pH value is controlled at 7.0 - 8.0. A composite bio - enzyme is added to the AO system. The main enzymes, namely the non - soluble organic matter catalytic enzyme, the microbial salt - tolerance enzyme, the soluble oil - type catalytic enzyme, the surfactant catalytic enzyme, the heterocyclic organic matter catalytic protease, and the humic acid catalytic enzyme, are configured in a ratio of 1:2:2:1:1:2. The composite coenzymes, namely the microbial carrier enzyme G, the microbial carrier enzyme F, the microbial carrier enzyme GC, and the microbial carrier enzyme P, are configured in a ratio of 1:1:1:1. The total dosage of the main enzyme is 5 g per ton of water, and the total dosage of the composite coenzyme is 20 g per ton of water. The dissolution water temperature of the main enzyme and the composite coenzyme is controlled at 20 - 30°C. The dissolution time of the bio - enzyme is 18 hours, and the reaction time after being added to the wastewater is 36 hours. After degradation is completed, the organic matter, ammonia nitrogen, and suspended solids in the coal leaching wastewater are removed through the MBR system; The water produced by the integrated AO + MBR system is pumped into the reverse osmosis system through a security filter to remove impurities such as dissolved salts and organic matter in the water. The deionized water produced by the reverse osmosis system enters the product water tank, and the concentrated brine enters the electrodialysis system. The concentrated brine is separated into fresh water and extreme liquid through an ion membrane. The TDS of the extreme liquid can reach 150,000 mg / L. Among them, the extreme liquid enters the multi - effect evaporation system, and after multi - effect evaporation, the extreme liquid crystallizes into salt. The fresh water is mixed with the MBR effluent and then recycled into the reverse osmosis system for desalination; The reverse osmosis product water and the multi - effect evaporation condensate enter the product water tank and are used as supplementary water for the dissolution reactor and then enter the system again.

[0026] The water quality data before and after wastewater treatment are shown in the following table.

[0027] Item Before treatment After treatment Unit pH 7.0-8.5 7.0-8.5 / CODCr ≤360 ≤50 mg / L SS ≤1000 ≤10 mg / L TDS ≤10000 ≤800 mg / L K+ ≤150 ≤100 mg / L Ca2+ ≤1100 ≤50 mg / L Mg2+ ≤350 ≤50 mg / L SO42- ≤1700 ≤300 mg / L Cl- ≤6000 ≤150 mg / L

Claims

1. A method for treating coal leaching wastewater containing high sodium, high chloride and rich organic matter by using biological enzymes, comprising the following steps: Step 1: The raw coal is crushed into coal particles with a diameter of 3mm to 10mm, and the coal particles are lifted to the dissolution reactor by a feeding pump to mix with the dissolution liquid. The dissolution liquid is weakly acidic desalted water, and the pH value is controlled at 3.0 to 4.0, the temperature is controlled at 20 to 35°C, and the reaction residence time is controlled at 60min to 100min. After the dissolution is completed, the coal particles enter the dewatering screen and the plate and frame filter press from the reactor outlet for dehydration to generate coal dissolution wastewater. When the TDS in the coal dissolution wastewater is greater than 10,000 mg / L, it is discharged from the dissolution reactor into the regulating tank, and the dissolution liquid is added to the dissolution reactor at the same time; Step 2: The coal dissolution wastewater is homogenized and uniformly distributed in the regulating tank. After the wastewater in the regulating tank reaches a certain amount, it is pumped to the integrated high-efficiency sedimentation system. The integrated high-efficiency sedimentation system is provided with a lime addition area, a flocculation area, and a sedimentation area. The pH value of the lime addition area is controlled at 9.5-11, the temperature is controlled at 25-40°C, and the reaction residence time is controlled at 20min-40min. The lime addition area reacts the bicarbonate in the coal dissolution wastewater with lime to form calcium carbonate by adding sodium carbonate and calcium hydroxide. At the same time, the excess calcium ions react with the added sodium carbonate to form calcium carbonate, and then enter the flocculation area. The colloids and suspended matter in the coal dissolution wastewater are strengthened to flocculate under the joint action of the high molecular organic flocculant and the returned sludge to form high-density alum flowers. The sludge is precipitated in the sedimentation area at room temperature for 10 hours and concentrated to form concentrated sludge. A part of the concentrated sludge is returned to the flocculation area, and a part is regularly discharged. The supernatant is further removed from fine particles through the inclined tube and enters the integrated AO+MBR system; Step 3: The temperature of the AO system is controlled at 25-35°C, the pH value is controlled at 7.0-8.0, and a composite biological enzyme is added to the AO system. The composite biological enzyme includes: A main enzyme and a composite coenzyme, wherein the main enzyme includes an insoluble organic matter catalytic enzyme, a microbial salt-tolerant enzyme, a soluble oil catalytic enzyme, a surfactant catalytic enzyme, a heterocyclic organic matter catalytic protease, and a humic acid catalytic enzyme; the composite coenzyme includes a microbial carrier enzyme G, a microbial carrier enzyme F, a microbial carrier enzyme GC, and a microbial carrier enzyme P; the main enzyme dosage is 3g to 5g per ton of water; the composite coenzyme dosage is 15g to 20g per ton of water; the main enzyme and the composite coenzyme dissolution water temperature is controlled at 20 to 30° C., the dissolution time is controlled at 18 to 24 hours, and the reaction time is 36 hours; the unreacted high molecular organic flocculant in the step 2 is degraded in the integrated AO+MBR system; after the reaction is completed, the organic matter, ammonia nitrogen, and suspended solids in the coal leaching wastewater are removed by the MBR system; the produced water is established by the enzyme system and maintained during the operation of the enzyme system, so as to ensure that the AO system can efficiently treat the leaching wastewater while maintaining the salt tolerance of the microorganisms; Step 4: The water produced by the integrated AO+MBR system passes through the security filter and is pumped into the reverse osmosis system to remove impurities such as dissolved salts and organic matter in the water. The deionized water produced by the reverse osmosis system enters the water production pool, and the concentrated brine enters the electrodialysis system; Step 5: After the concentrated brine passes through the electrodialysis system, it is separated into fresh water and polar liquid through an ion membrane. The polar liquid enters the multi-effect evaporation system, and the TDS reaches 150,000 mg / L. The fresh water is mixed with the MBR effluent and then circulated into the reverse osmosis system for desalination. Step six, after the polar liquid is collected, it enters the multi-effect evaporation system. After the multi-effect evaporation, the polar liquid crystallizes into salt, and the condensate enters the water production pool. The water in the water production pool enters the system again as the supplementary water of the dissolution reactor.

2. A method for treating high sodium, high chloride and organic-rich coal leaching wastewater using biological enzymes according to claim 1, characterized in that The macromolecular organic flocculant is PAM anionic polyacrylamide.

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