CN-118833944-B - PTA sewage quality-classifying recovery treatment system and recovery treatment method

Abstract

The invention belongs to the field of wastewater treatment, and relates to a PTA sewage quality-classifying recovery treatment system and a recovery treatment method. The system comprises a PTA process wastewater treatment system, an accident water treatment system and an oxidation tail gas washing wastewater treatment system, wherein the PTA process wastewater treatment system comprises a pretreatment unit, an anaerobic treatment unit, at least two sections of aerobic treatment units and an advanced treatment unit which are sequentially connected, the accident water treatment system comprises an accident pool and an accident water heat exchanger, the outlet of the accident pool is connected with the accident water heat exchanger, the oxidation tail gas washing wastewater treatment system comprises a filtration treatment unit, an ultrafiltration treatment unit, a nanofiltration treatment unit, a reverse osmosis treatment unit and a hydrogen placing treatment unit which are sequentially connected, the accident water heat exchanger is connected with the pretreatment unit, the nanofiltration treatment unit is connected with the anaerobic treatment unit, and the hydrogen placing treatment unit is connected with the aerobic treatment unit. The invention avoids the impact of accident water and oxidized tail gas washing wastewater on a treatment system, and efficiently treats the wastewater to reach the discharge standard.

Inventors

• PEI JIN
• ZHENG LEI
• AN JINGHUI
• GUO RUI
• Sun Lansun
• ZHANG YING
• SONG ZHIBO

Assignees

• 中国石化工程建设有限公司
• 中石化炼化工程（集团）股份有限公司

Dates

Publication Date

20260512

Application Date

20230424

Claims (18)

1. 1. The PTA sewage quality-classifying recovery treatment system is characterized by comprising a PTA process wastewater treatment system, an accident water treatment system and an oxidation tail gas washing wastewater treatment system; The PTA process wastewater treatment system comprises a pretreatment unit, an anaerobic treatment unit, an aerobic treatment unit and a deep treatment unit which are sequentially connected, wherein the aerobic treatment unit comprises at least two sections; The accident water treatment system comprises an accident pool and an accident water heat exchanger, wherein an outlet of the accident pool is connected with the accident water heat exchanger; the oxidation tail gas washing wastewater treatment system comprises a filtering treatment unit, an ultrafiltration treatment unit, a nanofiltration treatment unit, a reverse osmosis treatment unit and a hydrogen placing treatment unit which are sequentially connected, wherein the hydrogen placing treatment unit is used for enabling concentrated water of the reverse osmosis treatment unit to enter the hydrogen placing treatment unit and react with concentrated phosphoric acid, and a generated sodium dihydrogen phosphate solution is used as nutrient solution of an aerobic treatment unit, and a generated hydrogen bromide gas is sent to a PTA oxidation device to be used as a catalyst; the accident water heat exchanger is connected with the inlet of the pretreatment unit, the concentrated water outlet of the nanofiltration treatment unit is connected with the inlet of the anaerobic treatment unit, and the hydrogen-containing treatment unit is connected with the inlet of the aerobic treatment unit.
2. 2. The PTA wastewater quality recovery treatment system according to claim 1, wherein the pretreatment unit comprises a pretreatment heat exchanger and a homogenizing tank, wherein the homogenizing tank is provided with a stirring device; the anaerobic treatment unit comprises at least one group of conditioning tank-anaerobic reactor and an anaerobic water outlet heat exchanger, wherein the conditioning tank-anaerobic reactor is connected with the anaerobic water outlet heat exchanger, and the conditioning tank is provided with a pH adjusting device, a temperature adjusting device and a nutrient supplementing device; The aerobic treatment unit comprises a first-stage aerobic treatment unit and a second-stage aerobic treatment unit, wherein each stage of aerobic treatment unit is provided with at least one group of aerobic tanks-sedimentation tanks; the advanced treatment unit comprises an air floatation tank, a sand-adding and carbon-adding high-density tank and a monitoring tank which are connected in sequence; the accident water heat exchanger is connected with an inlet of a homogenizing pool, and the homogenizing pool is sequentially connected with at least one group of conditioning tank-anaerobic reactor, anaerobic water outlet heat exchanger, a first-stage aerobic pool, a first-stage sedimentation pool, a second-stage aerobic pool, a second-stage sedimentation pool, an air floatation pool, a sand-adding and charcoal-adding high-density pool and a monitoring pool; The concentrated water outlet of the nanofiltration treatment unit is connected with the inlet of the anaerobic reactor, and the hydrogen-placing treatment unit is connected with the inlet of the first-stage aerobic tank and/or the inlet of the second-stage aerobic tank.
3. 3. The PTA wastewater quality recovery treatment system according to claim 2, wherein, The number of the tempering tanks and the anaerobic reactors in each group of tempering tank-anaerobic reactors is 1:1 or 1:2, the outlet of the tempering tank is connected with the inlet of the anaerobic reactor, and at least one outlet of the anaerobic reactor is connected with the inlet of the tempering tank connected with the outlet of the anaerobic reactor.
4. 4. The PTA wastewater quality recovery treatment system according to claim 2, wherein, The aerobic treatment unit comprises a first-stage aerobic tank, a first-stage sedimentation tank, a second-stage aerobic tank and a second-stage sedimentation tank which are connected in sequence.
5. 5. The PTA wastewater quality recovery treatment system according to claim 2, wherein, The pretreatment unit is also provided with an acid-separating tank which is sequentially connected with the pretreatment heat exchanger and the homogenizing tank; the sand adding and carbon adding high-density tank comprises a contact tank, a coagulation tank, a curing tank and an inclined plate clarification tank which are sequentially arranged.
6. 6. A PTA sewage quality-classified recovery treatment method, which is characterized in that the recovery treatment method is carried out in the recovery treatment system according to any one of claims 1-5, and PTA process wastewater, accident water and oxidation tail gas washing wastewater respectively enter different systems to be treated by different methods; Wherein, the PTA process wastewater enters a PTA process wastewater treatment system for treatment according to the following steps of pretreatment, anaerobic treatment, two-stage aerobic treatment and advanced treatment; The accident water enters an accident water treatment system for treatment according to the following steps of homogenizing treatment and cooling treatment; The oxidized tail gas washing wastewater enters an oxidized tail gas washing wastewater treatment system for treatment according to the following steps of filtration treatment, ultrafiltration treatment, nanofiltration treatment, reverse osmosis treatment and hydrogen placing treatment; the accident water after cooling treatment enters a pretreatment unit and is mixed with PTA process wastewater for pretreatment, concentrated solution of a nanofiltration treatment unit enters an anaerobic treatment unit to be used as an alkalinity supplement, and sodium dihydrogen phosphate solution generated by a hydrogen treatment unit is used as nutrient solution of an aerobic treatment unit.
7. 7. The recovery treatment method according to claim 6, wherein the PTA process wastewater is treated by: Pretreatment, namely cooling PTA process wastewater in a pretreatment heat exchanger, and then stirring and mixing the wastewater in a homogenizing tank uniformly; Anaerobic treatment, namely, flowing the sewage in the homogenizing pool to a conditioning tank, adjusting the pH value, the nutrient content and the temperature, then, entering an anaerobic reactor to remove organic matters, and enabling the effluent of the anaerobic reactor to enter an anaerobic effluent heat exchanger to cool; the two-stage aerobic treatment, namely, after the cooled sewage flows into a first-stage aerobic tank to carry out first-stage aeration treatment, mud-water separation is carried out by a first-stage sedimentation tank, the effluent flows into a second-stage aerobic tank to carry out second-stage aeration treatment, and then the effluent enters a second-stage sedimentation tank to carry out mud-water separation; And (3) advanced treatment, namely, after suspended matters and residual COD in the water discharged from the second-stage sedimentation tank are further removed in the air floatation tank, the water enters a sand-adding and carbon-adding high-density tank, soluble organic matters in sewage are adsorbed, mud-water separation is carried out after flocculation sedimentation, and the water discharged from the sand-adding and carbon-adding high-density tank enters a monitoring tank.
8. 8. The recovery processing method according to claim 7, wherein the anaerobic reactor outlet water portion connected to the conditioning tank is returned to the conditioning tank.
9. 9. The recovery treatment method according to claim 7, wherein in the pretreatment step, the PTA process wastewater firstly enters an acid precipitation tank to precipitate TA acid, then enters a pretreatment heat exchanger to be cooled, the temperature of the mixed sewage is 35-40 ℃, and the residence time is more than or equal to 36 hours; In the anaerobic treatment step, the anaerobic reactor is a high-efficiency medium-temperature anaerobic reactor with the volume load of 10-20 kg COD/m < 3 >. D, the particle size of the domesticated anaerobic granular sludge is 0.3-3 mm, the effective granularity is more than or equal to 75%, the volatile suspended matters/total suspended matters are more than or equal to 0.7, the sedimentation speed of the granular sludge is 50-150 m/h, the sedimentation ratio is more than or equal to 90%, and the effluent of the anaerobic reactor is cooled to less than or equal to 35 ℃ through an anaerobic treatment heat exchanger; in the two-stage aerobic treatment step, the one-stage aerobic tank is a jet aeration aerobic tank or a microporous aeration aerobic tank, the COD removal rate is more than or equal to 90%, and the volume load is 2-4 kg COD/m < 3 >. D; The two-stage aerobic tank is a time-delay aeration aerobic tank or an MBBR aerobic tank, the COD removal rate is more than or equal to 80%, and the volume load is 0.3-0.35 kg COD/m <3 >. D; In the advanced treatment step, the pH value of the water discharged from the air floatation tank is less than or equal to 5, the water discharged from the air floatation tank firstly enters a contact tank to be mixed with active carbon, soluble organic matters in sewage are adsorbed, then enter a coagulation tank to react with a coagulant, then enter a curing tank to be mixed with polymer and micro sand, finally high-speed sedimentation is realized in an inclined plate clarification tank, mud-water separation is carried out, and the retention time of the monitoring tank is more than or equal to 2 hours.
10. 10. The recovery treatment method according to claim 9, wherein a portion of the primary sedimentation tank bottom sludge is returned to the primary aerobic tank, and another portion is sent to the surplus sludge treatment unit.
11. 11. The recovery treatment method according to claim 9, wherein a part of the bottom sludge of the secondary sedimentation tank is returned to the secondary aerobic tank, and the other part is sent to the surplus sludge treatment unit.
12. 12. The recovery processing method according to claim 6, wherein the accident water is processed by cooling the accident water by an accident water heat exchanger after the accident water enters an accident pool for full mixing and standing; The accident water comprises at least one of device drainage, hot alkali liquor, clear water flushing equipment wastewater and pipeline wastewater during device maintenance, wherein the temperature of the accident water is less than or equal to 95 ℃ and the pH value is 2-12; the accident water after cooling enters a pretreatment unit of PTA process wastewater.
13. 13. The recovery processing method according to claim 12, wherein the temperature of the accident water after the temperature reduction is 38-40 ℃.
14. 14. The recovery processing method according to claim 12, wherein the accident water after the temperature reduction enters a homogenizing tank.
15. 15. The recovery processing method according to claim 6, wherein the oxidation off-gas washing wastewater is treated by: filtering, namely filtering the oxidized tail gas washing wastewater in a filtering treatment unit to remove large particles and macromolecular organic matters in the oxidized tail gas washing wastewater; ultrafiltration, namely enabling the water discharged from the filtration treatment unit to enter the ultrafiltration treatment unit to further remove fine particles; Nanofiltration, namely, the effluent of the ultrafiltration treatment unit enters the nanofiltration treatment unit, sodium carbonate concentrate is separated out and recycled to the anaerobic treatment unit to be used as an alkalinity supplement; Reverse osmosis, namely, the effluent of the nanofiltration treatment unit enters the reverse osmosis treatment unit, and the permeate is recycled; And (3) hydrogen placing, namely, enabling the concentrated water of the reverse osmosis treatment unit to enter a hydrogen placing treatment unit to react with concentrated phosphoric acid, and enabling the generated sodium dihydrogen phosphate solution to serve as a nutrient solution of the aerobic treatment unit, and enabling the generated hydrogen bromide gas to be sent to a PTA oxidation device to serve as a catalyst.
16. 16. The recovery processing method according to claim 15, wherein the PTA oxidation tail gas washing wastewater is wastewater generated by passing PTA oxidation device tail gas through a washing tower.
17. 17. The recovery treatment method according to claim 16, wherein the filtration treatment unit is multi-medium filtration or active carbon filtration, the pore diameter of the ultrafiltration treatment unit is 4-6 nm, the interception efficiency of the nanofiltration treatment unit is more than or equal to 75%, and the salt content of the reverse osmosis concentrated solution is more than or equal to 10%.
18. 18. The recovery treatment method according to any one of claims 6 to 17, wherein the sewage of each treatment unit is lifted to the next treatment unit by gravity flow or a pump.

Description

PTA sewage quality-classifying recovery treatment system and recovery treatment method Technical Field The invention belongs to the field of wastewater treatment, and particularly relates to a PTA sewage quality-dividing recovery treatment system and a recovery treatment method. Background Refined terephthalic acid (PTA) is a main raw material for producing Polyester (PET), in recent years, the global polyester productivity speed-up drives the rapid increase of PTA demand, and according to data statistics in 2000-2021, china is the largest PTA production and consumption country in Asia. And a large amount of high-concentration sewage generated in the PTA production process is one of typical high-difficulty wastewater treatment in petrochemical industry. The PTA sewage generally comprises continuous production sewage, intermittent waste water, accident water and the like, wherein the continuous production sewage comprises acetic acid recovery waste water, catalyst recovery waste water, oxidation tail gas washing waste water, dryer exhaust washing waste water and crystallizer waste water, the intermittent waste water is waste water collected by a trench system of an oxidation device and a refining device, and the accident water is waste water generated by flushing equipment and pipelines during device maintenance. The traditional PTA sewage treatment is to mix the various waste water and treat the waste water, however, the water quality difference of the waste water generated in each stage is larger according to the production process difference. The organic pollutant in the waste water of the oxidation tail gas washing is single in component and low in concentration, and contains a large amount of sodium bromide and sodium carbonate, if the waste water directly enters a sewage treatment system, huge impact is caused on the system, and a large amount of sodium bromide and sodium carbonate resources are wasted. In addition, the accident water generated by flushing equipment and pipelines during the overhaul of the device has huge water quantity, the fluctuation of temperature and pH is large and can reach 95 ℃ at most, and the pH is between 2 and 12, and if the accident water is directly mixed with the process wastewater, the irreversible damage to the microorganisms of the subsequent anaerobic and aerobic units can be generated. Therefore, different treatment systems and methods are adopted for different types of PTA sewage, and the treatment systems are organically combined, so that the effluent is ensured to reach the standard stably, and the recycling utilization of the wastewater is realized. Disclosure of Invention The invention aims to solve the defects of the prior art, and provides a PTA sewage quality-dividing recovery treatment system and a recovery treatment method, which reduce the impact of accident water on the treatment system and simultaneously realize the recovery and utilization of resources in wastewater to the maximum extent. In order to achieve the above object, a first aspect of the present invention provides a PTA sewage quality-classified recovery processing system, which includes a PTA process wastewater treatment system, an accident water treatment system, and an oxidation tail gas washing wastewater treatment system; Wherein the PTA process wastewater treatment system comprises a pretreatment unit, an anaerobic treatment unit, at least two sections of aerobic treatment units and a deep treatment unit which are connected in sequence; The accident water treatment system comprises an accident pool and an accident water heat exchanger, wherein an outlet of the accident pool is connected with the accident water heat exchanger; The oxidation tail gas washing wastewater treatment system comprises a filtration treatment unit, an ultrafiltration treatment unit, a nanofiltration treatment unit, a reverse osmosis treatment unit and a hydrogen placing treatment unit which are connected in sequence; The accident water heat exchanger is connected with the pretreatment unit, the nanofiltration treatment unit is connected with the anaerobic treatment unit, and the hydrogen-placing treatment unit is connected with the aerobic treatment unit. According to the invention, preferably, in the PTA process wastewater treatment system, the pretreatment unit comprises a pretreatment heat exchanger and a homogenizing tank, and the homogenizing tank is provided with a stirring device. According to the invention, the anaerobic treatment unit comprises at least one group of tempering tank-anaerobic reactor and an anaerobic effluent heat exchanger, wherein the tempering tank-anaerobic reactor is connected with the anaerobic effluent heat exchanger, the tempering tank is provided with a pH adjusting device, a temperature adjusting device and a nutrient supplementing device, and preferably the number of the tempering tank and the anaerobic reactor in each group of tempering tank-anaerobic reactor is 1:1 or 1:2, the