Wastewater treatment system and process for POE alcohol production

Abstract

The invention discloses a wastewater treatment system and process for POE alcohol production, and the wastewater treatment system comprises a pretreatment unit, a deep oxidation unit, an efficient biodegradation unit, a catalytic oxidation electrolysis coupling unit, a salt-tolerant composite biological treatment unit and a post-treatment unit which are sequentially connected in series, the pretreatment unit comprises an adjusting tank, a demulsification reaction tank and a sedimentation tank which are sequentially connected in series, the deep oxidation unit comprises a supported bimetallic catalytic oxidation reactor, and the efficient biodegradation unit comprises an anaerobic bioreactor and an aerobic bioreactor. The catalytic oxidation and electrolysis coupling unit comprises a catalytic ozonation reactor and an iron-carbon micro-electrolysis reactor, the salt-tolerant composite biological treatment unit comprises a salt-tolerant hydrolysis acidification pool and a sequencing batch moving bed bio-membrane reactor, and the post-treatment unit comprises a precision filter and a disinfection pool. The method has the advantages that an integrated treatment system is constructed, process parameters are optimized, efficient purification of wastewater is achieved, it is ensured that effluent reaches the standard and is discharged, meanwhile, the treatment cost is reduced, and secondary pollution is reduced.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment system and process for POE alcohol production. Background Technology

[0002] POE polyol esters are base oils for air conditioning compressors, widely used in air conditioning compressors in residential, automotive, and large-scale air conditioning units. They possess excellent viscosity-temperature characteristics and oxidation resistance, and exhibit good compatibility and matching performance with new-generation green and environmentally friendly refrigerants. Among ester synthetic oils, complex esters have high viscosity and are easily biodegradable, making them more suitable as base oils for engine oils, refrigeration oils, and hydraulic oils with high environmental protection requirements. They also possess good boundary lubrication properties, making them suitable as both base oils and lubricating additives.

[0003] The production of POE alcohol generates a large amount of high-concentration organic wastewater, which mainly comes from the mother liquor of transesterification reaction, product washing wastewater, and equipment cleaning wastewater. This type of wastewater has the following significant characteristics: (1) high COD concentration, usually reaching 5000-30000 mg / L, or even higher; (2) contains a large amount of recalcitrant ester compounds, polyols, unreacted raw materials and catalyst residues, etc., with poor biodegradability (BOD5 / COD is usually below 0.3); (3) has strong emulsifying properties, and conventional physical methods are difficult to achieve oil-water separation; (4) water quality fluctuates greatly, and the composition and concentration of wastewater generated by different production processes vary greatly. Summary of the Invention

[0004] The purpose of this invention is to provide a wastewater treatment system and process for POE alcohol production, construct an integrated treatment system and optimize process parameters to achieve efficient wastewater purification, ensure that the effluent meets discharge standards, and at the same time reduce treatment costs and reduce secondary pollution.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A wastewater treatment system for POE alcohol production, characterized in that it comprises a pretreatment unit, a deep oxidation unit, a high-efficiency biodegradation unit, a catalytic oxidation-electrolysis coupling unit, a salt-tolerant composite biological treatment unit, and a post-treatment unit connected in series. The pretreatment unit includes an equalization tank, a demulsification reaction tank, and a sedimentation tank connected in series. The deep oxidation unit includes a supported bimetallic catalytic oxidation reactor. The high-efficiency biodegradation unit includes an anaerobic bioreactor and an aerobic bioreactor connected in series. The catalytic oxidation-electrolysis coupling unit includes a catalytic ozone oxidation reactor and an iron-carbon micro-electrolysis reactor connected in series. The salt-tolerant composite biological treatment unit includes a salt-tolerant hydrolysis acidification tank and a sequencing batch moving bed biofilm reactor connected in series. The post-treatment unit includes a precision filter and a disinfection tank connected in series.

[0006] Preferably, the pretreatment unit includes a stirring device and a reagent dosing port in the demulsification reaction tank, and the sedimentation tank has a sludge discharge port at the bottom.

[0007] Preferably, the supported bimetallic catalytic oxidation reactor in the deep oxidation unit is filled with a Fe-Ni / γ-Al2O3 supported catalyst, wherein the Fe loading is 5-8 wt%, the Ni loading is 2-3 wt%, and the catalyst specific surface area is 180-220 m². 2 / g, with a pore size of 5-20nm, and an oxidant inlet and an exhaust outlet at the top.

[0008] Preferably, the anaerobic bioreactor is filled with modified polyurethane packing material containing anaerobic microorganisms, and the aerobic bioreactor is filled with modified ceramsite packing material containing aerobic microorganisms.

[0009] Preferably, the catalytic ozone oxidation reactor is filled with a composite catalyst supported on transition metal oxides and activated carbon.

[0010] Preferably, the hydrolysis acidification tank contains salt-tolerant facultative bacteria that have been acclimatized by POE alcohol wastewater over a long period of time.

[0011] Preferably, the sequencing batch moving bed biofilm reactor is filled with hydrophilic modified suspended packing material with high specific surface area, and the biofilm is enriched with salt-tolerant aerobic bacteria and nitrifying bacteria.

[0012] Preferably, the precision filter includes multiple sets of hollow fiber ultrafiltration membranes arranged in parallel, and the disinfection tank is equipped with an ultraviolet disinfection device.

[0013] A wastewater treatment process for POE alcohol production includes the following steps: POE alcohol production wastewater is introduced into an equalization tank to adjust the pH to 6.5-7.5 and control the water temperature at 25-35℃. The adjusted wastewater then enters a demulsification reaction tank, where a compound demulsifier is added through a reagent dosing port at a dosage of 0.1-0.3% of the wastewater mass. The reaction is carried out at a stirring speed of 150-200 r / min for 20-30 min. Subsequently, the wastewater is introduced into a sedimentation tank and allowed to settle for 40-60 min to remove the upper scum and the bottom sludge, resulting in pretreated effluent. The pretreated effluent is introduced into a supported bimetallic catalytic oxidation reactor, and hydrogen peroxide is added as an oxidant. The amount of hydrogen peroxide added is 1.2-1.5 times the total COD of the wastewater. The reaction temperature is controlled at 40-50℃ and the reaction time is 60-90 min. During the reaction, a small amount of oxygen and carbon dioxide generated are collected through the tail gas emission port to obtain the oxidized effluent. The effluent from the oxidation treatment is introduced into an anaerobic bioreactor, where the temperature is controlled at 35-38℃, the pH at 7.0-7.8, and the hydraulic retention time at 24-36 hours. Anaerobic microorganisms on modified polyurethane packing degrade the recalcitrant organic matter in the wastewater. The effluent after anaerobic treatment then enters an aerobic bioreactor, where the dissolved oxygen concentration is controlled at 2-4 mg / L, the temperature at 28-32℃, the pH at 6.8-7.5, and the hydraulic retention time at 12-24 hours. Aerobic microorganisms on modified ceramsite packing further degrade the organic matter, resulting in biodegraded effluent. The biodegraded effluent is pumped into a catalytic ozone oxidation reactor, with the ozone dosage controlled at 0.8-1.2 times the COD mass of the wastewater and the hydraulic retention time at 60-90 minutes. The effluent then flows by gravity into an iron-carbon micro-electrolysis reactor with a hydraulic retention time of 40-60 minutes, where pollutants are further degraded using an Fe-C galvanic cell reaction. The effluent from micro-electrolysis enters a salt-resistant hydrolysis acidification tank with a hydraulic retention time of 24-36 hours, converting complex organic matter into small-molecule organic acids. The effluent from the hydrolysis acidification tank then enters a sequencing batch moving bed biofilm reactor, which operates with intermittent aeration, controlling dissolved oxygen at 2-4 mg / L, with a total hydraulic retention time of 36-48 hours, to achieve deep removal of organic matter and partial nitrification of ammonia nitrogen. The effluent is then introduced into a precision filter, with the filtration pressure controlled at 0.1-0.2 MPa. A hollow fiber ultrafiltration membrane removes residual suspended solids, microbial flocs, and some large organic molecules from the water, reducing the turbidity of the filtered effluent to below 1 NTU. The filtered effluent then enters a disinfection tank and is treated with an ultraviolet disinfection device for 15-20 minutes, with an ultraviolet intensity ≥30 μW / cm². 2 It kills bacteria, viruses and other pathogens in the water, and after meeting the standards, it can be directly discharged or reused for washing the floors of production workshops, greening and other purposes.

[0014] Preferably, the composite demulsifier is composed of an inorganic demulsifier, an organic flocculant, and a coagulant aid mixed in a mass ratio of 3:1:0.5, wherein the inorganic demulsifier is polyaluminum chloride, the organic flocculant is polyacrylamide, and the coagulant aid is bentonite.

[0015] In summary, the present invention has the following beneficial effects: the treatment system and process of the present invention have a significantly better treatment effect on POE alcohol production wastewater than the prior art: the COD removal rate can reach more than 99.2%, the ester compound removal rate is ≥99.5%, the SS removal rate is ≥99.3%, and all the indicators of the final effluent meet the Class I standard of the "Integrated Wastewater Discharge Standard" (GB 8978-1996). Attached Figure Description

[0016] Figure 1 This is a structural diagram of the wastewater treatment system for POE alcohol production according to the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation on the present invention.

[0018] like Figure 1 The wastewater treatment system for POE alcohol production shown includes a pretreatment unit, a deep oxidation unit, a high-efficiency biodegradation unit, a catalytic oxidation-electrolysis coupling unit, a salt-tolerant composite biological treatment unit, and a post-treatment unit connected in series. The pretreatment unit includes an equalization tank 1, a demulsification reaction tank 2, and a sedimentation tank 3 connected in series. The deep oxidation unit includes a supported bimetallic catalytic oxidation reactor 4. The high-efficiency biodegradation unit includes an anaerobic bioreactor 5 and an aerobic bioreactor 6 connected in series. The catalytic oxidation-electrolysis coupling unit includes a catalytic ozone oxidation reactor 7 and an iron-carbon micro-electrolysis reactor 8 connected in series. The salt-tolerant composite biological treatment unit includes a salt-tolerant hydrolysis acidification tank 9 and a sequencing batch moving bed biofilm reactor 10 connected in series. The post-treatment unit includes a precision filter 11 and a disinfection tank 12 connected in series.

[0019] The pretreatment unit includes a demulsification reaction tank 2 with a stirring device and a reagent dosing port, and a sedimentation tank 3 with a sludge discharge port at the bottom.

[0020] The supported bimetallic catalytic oxidation reactor 4 in the deep oxidation unit is filled with a Fe-Ni / γ-Al2O3 supported catalyst, wherein the Fe loading is 5-8 wt% and the Ni loading is 2-3 wt%, and the catalyst specific surface area is 180-220 m². 2 / g, with a pore size of 5-20nm, and an oxidant inlet and an exhaust outlet at the top.

[0021] Anaerobic bioreactor 5 is filled with modified polyurethane packing material containing anaerobic microorganisms, and aerobic bioreactor 6 is filled with modified ceramsite packing material containing aerobic microorganisms.

[0022] The catalytic ozone oxidation reactor 7 is filled with a composite catalyst supported on transition metal oxides and activated carbon.

[0023] Salt-tolerant facultative bacteria, acclimatized by POE alcohol wastewater over a long period of time, were added to the hydrolysis acidification tank.

[0024] The sequencing batch moving bed biofilm reactor 10 is filled with hydrophilic modified suspended packing material with high specific surface area, and salt-tolerant aerobic bacteria and nitrifying bacteria are enriched on the biofilm.

[0025] The precision filter 11 includes multiple sets of hollow fiber ultrafiltration membranes arranged in parallel, and the disinfection tank 12 is equipped with an ultraviolet disinfection device.

[0026] A wastewater treatment process for POE alcohol production includes the following steps: POE alcohol production wastewater is introduced into equalization tank 1 to adjust the pH to 6.5-7.5 and control the water temperature at 25-35℃. At the same time, the wastewater flow rate is adjusted to ensure the stable operation of the subsequent treatment unit. The adjusted wastewater enters demulsification reaction tank 2, where a compound demulsifier is added through the reagent dosing port at a dosage of 0.1-0.3% of the wastewater mass. The reaction is carried out at a stirring speed of 150-200 r / min for 20-30 minutes to fully break down the emulsion system in the wastewater, causing colloids and suspended solids to coagulate and form flocs. Subsequently, the wastewater is introduced into sedimentation tank 3 and allowed to settle for 40-60 minutes to remove the upper scum and the bottom sludge, resulting in pretreated effluent. The sludge produced in the sedimentation tank is concentrated in a sludge thickening tank and then sent to a plate and frame filter press for dewatering. The dewatered sludge is then sent to a hazardous waste treatment center for disposal to avoid secondary pollution. The pretreated effluent is introduced into the supported bimetallic catalytic oxidation reactor 4, and hydrogen peroxide is added as an oxidant. The amount of hydrogen peroxide added is 1.2-1.5 times the total COD of the wastewater. The reaction temperature is controlled at 40-50℃ and the reaction time is 60-90 min. During the reaction, a small amount of oxygen and carbon dioxide generated are collected through the tail gas emission port to obtain the oxidized effluent. Under the catalytic action of the Fe-Ni / γ-Al2O3 supported catalyst, hydrogen peroxide decomposes to generate a large number of hydroxyl radicals. The hydroxyl radicals rapidly oxidize and decompose the recalcitrant ester compounds, polyols and other organic pollutants in the wastewater, converting them into easily biodegradable small molecule organic matter. After the reaction, the supported bimetallic catalyst in the reactor is recovered by magnetic separation. The recovered catalyst can be reused after acid washing and activation treatment, and the number of reuses is not less than 10. The effluent from the oxidation treatment is introduced into anaerobic bioreactor 5, where the temperature is controlled at 35-38℃, the pH at 7.0-7.8, and the hydraulic retention time at 24-36 hours. A large number of anaerobic microorganisms (such as acid-producing bacteria and methanogens) adhere to the surface of the modified polyurethane packing. Through acid-producing fermentation and methanogenesis, these microorganisms further degrade small-molecule organic matter in the wastewater into gases such as methane and carbon dioxide, removing some organic pollutants. The effluent after anaerobic treatment then enters aerobic bioreactor 6, where the dissolved oxygen concentration is controlled at 2-4 mg / L, the temperature at 28-32℃, the pH at 6.8-7.5, and the hydraulic retention time at 12-24 hours. A large number of aerobic microorganisms (such as heterotrophic bacteria and nitrifying bacteria) adhere to the surface of the modified ceramsite packing. Under aerobic conditions, these microorganisms completely degrade the residual organic pollutants in the wastewater into carbon dioxide and water, while simultaneously removing pollutants such as ammonia nitrogen, resulting in biodegraded effluent. The biodegraded effluent is pumped into the catalytic ozone oxidation reactor 7, with the ozone dosage controlled at 0.8-1.2 times the COD mass of the wastewater and the hydraulic retention time at 60-90 minutes. The effluent then flows by gravity into the iron-carbon micro-electrolysis reactor 8, with a hydraulic retention time of 40-60 minutes, where pollutants are further degraded using the Fe-C galvanic cell reaction. The effluent from micro-electrolysis enters the salt-resistant hydrolysis acidification tank 9, with a hydraulic retention time of 24-36 hours, converting complex organic matter into small molecule organic acids. The effluent from the hydrolysis acidification tank enters the sequencing batch moving bed biofilm reactor 10, which operates in an intermittent aeration mode, controlling the dissolved oxygen at 2-4 mg / L, with a total hydraulic retention time of 36-48 hours, to complete the deep removal of organic matter and partial nitrification of ammonia nitrogen. The effluent is then introduced into a precision filter 11, with the filtration pressure controlled at 0.1-0.2 MPa. A hollow fiber ultrafiltration membrane removes residual suspended solids, microbial flocs, and some large organic molecules from the water, reducing the turbidity of the filtered effluent to below 1 NTU. The filtered effluent then enters a disinfection tank 12, where it is treated with an ultraviolet disinfection device for 15-20 minutes, with an ultraviolet intensity ≥30 μW / cm². 2 It kills bacteria, viruses and other pathogens in the water, and after meeting the standards, it can be directly discharged or reused for washing the floors of production workshops, greening and other purposes.

[0027] The composite demulsifier is composed of an inorganic demulsifier, an organic flocculant, and a coagulant aid mixed in a mass ratio of 3:1:0.5. The inorganic demulsifier is polyaluminum chloride, the organic flocculant is polyacrylamide, and the coagulant aid is bentonite.

[0028] The treatment system and process of this invention have significantly better treatment effects on POE alcohol production wastewater than existing technologies: COD removal rate can reach over 99.2%, ester compound removal rate ≥ 99.5%, SS removal rate ≥ 99.3%, and all indicators of the final effluent meet the Class I standard of the "Integrated Wastewater Discharge Standard" (GB 8978-1996).

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the scope of its essence and protection. Such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A wastewater treatment system for POE alcohol production, characterized in that, The system comprises a pretreatment unit, a deep oxidation unit, a high-efficiency biodegradation unit, a catalytic oxidation-electrolysis coupling unit, a salt-tolerant composite biological treatment unit, and a post-treatment unit connected in series. The pretreatment unit includes an equalization tank, a demulsification reaction tank, and a sedimentation tank connected in series. The deep oxidation unit includes a supported bimetallic catalytic oxidation reactor. The high-efficiency biodegradation unit includes an anaerobic bioreactor and an aerobic bioreactor connected in series. The catalytic oxidation-electrolysis coupling unit includes a catalytic ozone oxidation reactor and an iron-carbon micro-electrolysis reactor connected in series. The salt-tolerant composite biological treatment unit includes a salt-tolerant hydrolysis acidification tank and a sequencing batch moving bed biofilm reactor connected in series. The post-treatment unit includes a precision filter and a disinfection tank connected in series.

2. The wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The pretreatment unit includes a demulsification reaction tank with a stirring device and a reagent dosing port, and the sedimentation tank has a sludge discharge port at the bottom.

3. The wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The deep oxidation unit contains a supported bimetallic catalytic oxidation reactor filled with a Fe-Ni / γ-Al₂O₃ supported catalyst, wherein the Fe loading is 5-8 wt%, the Ni loading is 2-3 wt%, and the catalyst specific surface area is 180-220 m². 2 / g, with a pore size of 5-20nm, and an oxidant inlet and an exhaust outlet at the top.

4. A wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The anaerobic bioreactor is filled with modified polyurethane packing material containing anaerobic microorganisms, and the aerobic bioreactor is filled with modified ceramsite packing material containing aerobic microorganisms.

5. A wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The catalytic ozone oxidation reactor is filled with a composite catalyst supported on transition metal oxides and activated carbon.

6. A wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The hydrolysis acidification tank contains salt-tolerant facultative bacteria that have been acclimatized by POE alcohol wastewater over a long period of time.

7. A wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The sequencing batch moving bed biofilm reactor is filled with hydrophilic modified suspended packing material with high specific surface area, and the biofilm is enriched with salt-tolerant aerobic bacteria and nitrifying bacteria.

8. A wastewater treatment system for POE alcohol production according to claim 1, characterized in that: The precision filter includes multiple sets of hollow fiber ultrafiltration membranes arranged in parallel, and the disinfection tank is equipped with an ultraviolet disinfection device.

9. A wastewater treatment process for POE alcohol production according to any one of claims 1 to 8, characterized in that, Includes the following steps: POE alcohol production wastewater is introduced into an equalization tank to adjust the pH to 6.5-7.5 and control the water temperature at 25-35℃. The adjusted wastewater then enters a demulsification reaction tank, where a compound demulsifier is added through a reagent dosing port at a dosage of 0.1-0.3% of the wastewater mass. The reaction is carried out at a stirring speed of 150-200 r / min for 20-30 min. Subsequently, the wastewater is introduced into a sedimentation tank and allowed to settle for 40-60 min to remove the upper scum and the bottom sludge, resulting in pretreated effluent. The pretreated effluent is introduced into a supported bimetallic catalytic oxidation reactor, and hydrogen peroxide is added as an oxidant. The amount of hydrogen peroxide added is 1.2-1.5 times the total COD of the wastewater. The reaction temperature is controlled at 40-50℃ and the reaction time is 60-90 min. During the reaction, a small amount of oxygen and carbon dioxide generated are collected through the tail gas emission port to obtain the oxidized effluent. The effluent from the oxidation treatment is introduced into an anaerobic bioreactor, where the temperature is controlled at 35-38℃, the pH at 7.0-7.8, and the hydraulic retention time at 24-36 hours. Anaerobic microorganisms on modified polyurethane packing degrade the recalcitrant organic matter in the wastewater. The effluent after anaerobic treatment then enters an aerobic bioreactor, where the dissolved oxygen concentration is controlled at 2-4 mg / L, the temperature at 28-32℃, the pH at 6.8-7.5, and the hydraulic retention time at 12-24 hours. Aerobic microorganisms on modified ceramsite packing further degrade the organic matter, resulting in biodegraded effluent. The biodegraded effluent is pumped into a catalytic ozone oxidation reactor, with the ozone dosage controlled at 0.8-1.2 times the COD mass of the wastewater and the hydraulic retention time at 60-90 minutes. The effluent then flows by gravity into an iron-carbon micro-electrolysis reactor with a hydraulic retention time of 40-60 minutes, where pollutants are further degraded using an Fe-C galvanic cell reaction. The effluent from micro-electrolysis enters a salt-resistant hydrolysis acidification tank with a hydraulic retention time of 24-36 hours, converting complex organic matter into small-molecule organic acids. The effluent from the hydrolysis acidification tank then enters a sequencing batch moving bed biofilm reactor, which operates with intermittent aeration, controlling dissolved oxygen at 2-4 mg / L, with a total hydraulic retention time of 36-48 hours, to achieve deep removal of organic matter and partial nitrification of ammonia nitrogen. The effluent is then introduced into a precision filter, with the filtration pressure controlled at 0.1-0.2 MPa. A hollow fiber ultrafiltration membrane removes residual suspended solids, microbial flocs, and some large organic molecules from the water, reducing the turbidity of the filtered effluent to below 1 NTU. The filtered effluent then enters a disinfection tank and is treated with an ultraviolet disinfection device for 15-20 minutes, with an ultraviolet intensity ≥30 μW / cm². 2 It kills bacteria, viruses and other pathogens in the water, and after meeting the standards, it can be directly discharged or reused for washing the floors of production workshops, greening and other purposes.

10. A wastewater treatment process for POE alcohol production according to claim 9, characterized in that: The composite demulsifier is composed of an inorganic demulsifier, an organic flocculant, and a coagulant aid mixed in a mass ratio of 3:1:0.

5. The inorganic demulsifier is polyaluminum chloride, the organic flocculant is polyacrylamide, and the coagulant aid is bentonite.

Images