A method for advanced treatment of photoelectric medical intermediate wastewater

Abstract

A photoelectric medical intermediate wastewater treatment method, aiming at the characteristics of high salt, high concentration, difficult degradation and high biological toxicity of the wastewater, adopts a combined process of "classification collection - targeted pretreatment - comprehensive biochemical - deep oxidation": the high-salt wastewater is pretreated by coagulation sedimentation + evaporation desalination, the high-concentration and difficult-to-degrade wastewater is pretreated by coagulation sedimentation + micro-electrolysis-fenton coupling oxidation, the pretreated wastewater is mixed with domestic sewage to enter a hydrolysis acidification tank to improve the biodegradability, then most of the organic matters are degraded by a UASB anaerobic reactor, then deep denitrification is realized by a two-stage AO tank with step feeding, and finally, the bottom treatment is realized by fenton oxidation + neutralization precipitation. The present application solves the problems of high salt inhibition, incomplete removal of difficult-to-degrade organic matters and poor denitrification effect in the prior art, the effluent CODcr after treatment is less than or equal to 180 mg / L, ammonia nitrogen is less than or equal to 25 mg / L, total nitrogen is less than or equal to 40 mg / L, which meets the discharge standard, and the operation cost is low, the stability is strong, and the present application has practical application value.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to a method for the deep treatment of wastewater from the production of high-salt, high-concentration, and highly biotoxic optoelectronic pharmaceutical intermediates. The method is applicable to the comprehensive wastewater treatment from the production of 3-bromocarbazole, N-BOC piperazine, L-carnosine, 4-methyldiphenylamine, 4-bromobiphenyl optoelectronic materials, and o-nitrobenzyl alcohol and lithocholic acid pharmaceutical intermediates. Background Technology

[0002] Wastewater from the production of optoelectronic pharmaceutical intermediates includes process mother liquor, equipment cleaning water, and floor washing water. The water quality presents five major challenges: ① Complex pollutant composition, containing halogenated aromatic hydrocarbons, aniline, toluene, xylene, organic solvents, heavy metal catalyst byproducts; ② Poor biodegradability, with a B / C ratio of only 0.1–0.2, and a large amount of aromatic substances exhibiting strong biological inhibition; ③ Some process mother liquors contain salts exceeding 100,000 mg / L, and direct entry of high salts into the biological system can cause microbial salt poisoning; ④ Extremely large fluctuations in total nitrogen and COD concentrations, resulting in strong shock loads; ⑤ Volatile organic waste gas is emitted from the production tanks and sludge dewatering section, and the lack of corresponding waste gas treatment can easily cause odor pollution in the plant area.

[0003] Existing conventional processing methods have obvious flaws: Without separate collection based on water quality, ultra-high salinity wastewater is directly mixed into the biological treatment unit, which significantly reduces the activity of microorganisms and makes it difficult to consistently meet the standards for COD and total nitrogen. Using only a single Fenton oxidation pretreatment without iron-carbon micro-electrolysis coupling results in low ring-opening degradation efficiency of macromolecular toxins, large reagent dosage, and high operating costs. Using only a single-stage AO biological process results in uneven carbon source distribution. Relying solely on traditional nitrification-denitrification for nitrogen removal, the total nitrogen removal rate is generally below 60%, making it difficult to meet stringent indirect emission standards. The process only considers the main wastewater flow and lacks supporting units for waste gas collection and co-processing of sludge and hazardous waste, which cannot meet the integrated environmental protection acceptance requirements of chemical enterprises. Without multi-stage oxidation as a backup, trace amounts of non-degradable organic matter remain in the biochemical effluent, resulting in excessive fluctuations in COD and color.

[0004] Existing publicly available technologies mostly target single optoelectronic materials or single pharmaceutical wastewater, lacking complete processes adapted to mixed wastewater with ultra-high salinity and ultra-high concentration, resulting in poor stability for industrial implementation. Therefore, developing a complete treatment method that integrates pretreatment based on different wastewater types, multi-stage biochemical coupling for deep denitrification, and co-treatment of waste gas and sludge is a pressing technical challenge in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for the deep treatment of wastewater from optoelectronic pharmaceutical intermediates. This method can effectively solve the problem of ensuring stable discharge of ultra-high salinity, high toxicity, and high concentration wastewater that meets emission standards. It also integrates waste gas and sludge treatment, reduces energy consumption for reagents and aeration, and enhances the system's resistance to shocks.

[0006] The technical solution provided by this invention is: a method for the deep treatment of wastewater from optoelectronic pharmaceutical intermediates, comprising the following steps: S1. Classified collection: High-salt wastewater generated by the production process is collected in high-salt wastewater pool 1. Equipment and floor cleaning wastewater is collected in high-concentration wastewater pool 4 after removing large particulate impurities by screen. Domestic sewage in the factory area is collected in collection well 8a after pretreatment by screen. S2. Differentiated and targeted preprocessing: S21. High-salinity wastewater desalination pretreatment: High-salinity wastewater is pumped into the first coagulation sedimentation tank 2, and the pH is adjusted to 6.5-8.5. PAC and PAM are added for coagulation sedimentation to separate suspended solids. The supernatant is sent to the low-temperature vacuum evaporation system 3 for desalination. The desalination rate is ≥95%, and the removal rate of macromolecular organic matter is ≥90%. The evaporation condensate is discharged into the high-concentration wastewater tank 4 to mix with the high-concentration recalcitrant wastewater. The low-temperature evaporation temperature is 45℃ and the vacuum degree is 0.09MPa, which greatly reduces the evaporation energy consumption and avoids the secondary decomposition of organic matter at high temperature to generate new pollutants.

[0007] S22. Pretreatment of High-Concentration, Recalcitrant Wastewater with Coupled Oxidation: The mixed wastewater in the high-concentration wastewater tank 4 is sent to the second coagulation sedimentation tank 5. The pH is adjusted to 6.5-8.5. PAC and PAM are added for coagulation and sedimentation to separate suspended solids. The supernatant enters the micro-electrolysis-Fenton coupled reaction tank 6 and is acidified to pH 2.5-3.5. The iron-carbon packing forms a galvanic cell to break the benzene ring and the macromolecular structure of halogenated hydrocarbons. Ferrous salt and hydrogen peroxide are added simultaneously for aeration to generate hydroxyl radicals for deep oxidation and detoxification. Micro-electrolysis is performed for 30 minutes and Fenton reaction for 45 minutes. The effluent from the reaction enters the first neutralization sedimentation tank and the pH is adjusted to 6.5-8.5. PAM is added for sludge-water separation to remove the iron salt suspended solids generated by oxidation. S3. Comprehensive homogenization and regulation: The domestic sewage from the collection well 8a and the effluent from the first neutralization sedimentation tank 7 are sent to the comprehensive regulation tank 8 for homogenization and equalization, and low-intensity pre-aeration to dilute the salinity of the pretreated wastewater to less than 5000 mg / L, thereby eliminating the inhibition of high salt on the subsequent biological system. S4. Biochemical pretreatment: The wastewater after comprehensive adjustment is sent to the hydrolysis acidification tank 9. Under anoxic conditions, large molecular toxic organic matter is broken down, and the B / C ratio is increased from 0.2-0.25 to 0.35-0.4, which significantly improves the biodegradability of the wastewater; the hydraulic retention time is 12h, and the dissolved oxygen is ≤0.5mg / L; S5. Anaerobic Deep Degradation: The hydrolyzed and acidified wastewater is pumped into anaerobic reactor 10, where anaerobic microorganisms significantly degrade organic pollutants. The reactor produces digested gas, digested liquid, and granular sludge through three-phase separation. The digested gas is then incinerated by a flare after hydrogen sulfide removal through a desulfurization system. The reactor has a volumetric loading rate of 3 kg COD / (m³・d), a hydraulic retention time of 40 h, and a COD removal rate of over 80%, significantly reducing the organic load in the subsequent AO tank. S6. Segmented Influent Two-Stage AO Coupled Deep Denitrification: The digestate from anaerobic reactor 10 is fed into a primary AO tank 11 and a secondary AO tank 12 in a segmented ratio of 8:2. The primary AO tank 11 includes a first anoxic tank 11-1 and a first aerobic tank 11-2 connected in sequence. 200% of the mixed liquor from the first aerobic tank 11-2 is recycled back to the first anoxic tank 11-1. The secondary AO tank 12 includes a second anoxic tank 12-1 and a second aerobic tank 12-2 connected in sequence. 100% of the mixed liquor from the second aerobic tank 12-2 is recycled back to the second anoxic tank 12-1. The effluent from the first aerobic tank 11-2... Water is introduced into the second anoxic tank 12-1. Suspended biological packing is added to both the anoxic and aerobic tanks. The biofilm on the packing simultaneously enriches denitrifying bacteria, short-cut denitrifying bacteria, and anaerobic ammonia oxidizing bacteria, achieving synergistic nitrogen removal through multiple pathways of traditional nitrification-denitrification, short-cut denitrification coupled with anaerobic ammonia oxidation. The microporous aeration intensity in the two aerobic tanks is 1.0-2.0 m³ / (m²·h), maintaining dissolved oxygen at 2-4 mg / L. Submersible mixers are installed in the anoxic tanks to ensure thorough mixing of carbon source, nitrification liquid, and sludge. A grid prevents suspended packing from crossing the tanks, ensuring stable enrichment of functional bacteria in each unit, and the overall total nitrogen removal rate can reach over 95%. S7. Secondary sedimentation solid-liquid separation: The effluent from the secondary AO tank 12 is sent to the secondary sedimentation tank 13 for sludge-water separation; the secondary sedimentation sludge is divided into two streams, one stream of 50% of the sludge is returned to the first anoxic tank of the primary AO tank to maintain the sludge concentration of 3-5 g / L, and the remaining sludge is discharged into the sludge tank. S8. Deep oxidation: The effluent from the secondary sedimentation tank 13 is sent to the Fenton oxidation tank 14. Acid is added to adjust the pH to 2.5-3.5, and ferrous salt and hydrogen peroxide are added for Fenton oxidation to remove residual recalcitrant organic matter, serving as a backup unit for biochemical effluent. S9, Neutralization and Sedimentation: The wastewater after Fenton oxidation is sent to the second neutralization and sedimentation tank 15. Alkali is added to adjust the pH to 6.5-8.5, and PAC and PAM are added for coagulation and sedimentation to remove iron salt suspensions and trace organic intermediates produced by oxidation. S10, Standard Discharge: The supernatant from the second neutralization sedimentation tank 15 enters the clear water tank 16 and is discharged after passing the test; S11. Centralized treatment of waste gas: high-salt wastewater pool, high-concentration wastewater pool, comprehensive regulating pool, hydrolysis acidification pool, anaerobic reactor, sludge pool, sludge dewatering and sealed gas collection, waste gas sequentially passes through two-stage spray towers, first-stage alkaline washing, second-stage acid washing, activated carbon-microbial composite packing biological filter for degradation, exhaust by induced draft fan to eliminate organic odor in the plant area. S12. Unified disposal of sludge: All sludge generated from each coagulation sedimentation unit, hydrolysis acidification, and anaerobic reactor is discharged into the sludge tank, dewatered by plate and frame dewatering, and the moisture content of the dewatered sludge is ≤80%; the dewatered filtrate is returned to the integrated equalization tank for repeated treatment; dewatered sludge and evaporation crystallization salt residue are both hazardous wastes and are disposed of in compliance with regulations by outsourcing.

[0008] The core innovation of this invention lies in: Differentiated pretreatment system with separate flow of different types of wastewater: ultra-high salinity wastewater is desalinated by low-temperature evaporation, and high concentration toxic wastewater is pretreated by micro-electrolysis-Fenton coupled oxidation, which controls the salinity of the wastewater entering the biological system to below 5000 mg / L. The pretreatment removal rate of recalcitrant organic matter is over 70%, which completely solves the problem of high salinity and high toxicity inhibiting biological sludge. Hydrolysis acidification + UASB dual-stage anaerobic degradation: pre-hydrolysis acidification improves biodegradability, while UASB significantly reduces COD load and lowers subsequent aeration energy consumption by 20%; Two-stage AO with multiple coupling denitrification: The 8:2 segmented influent balances carbon source distribution, and the suspended packing simultaneously enriches short-cut denitrification and anaerobic ammonia oxidation functional bacteria. Multiple denitrification pathways are superimposed, and the total nitrogen removal rate is much higher than that of conventional single-stage AO. Two-stage Fenton staged oxidation: pretreatment coupled with Fenton detoxification and end-of-pipe Fenton backstop, providing dual protection for stable effluent compliance and strong resistance to water quality fluctuations; The integrated and coordinated treatment of wastewater, waste gas, and sludge fully covers the entire environmental protection process of chemical enterprises and meets the requirements of environmental impact assessment and acceptance.

[0009] Compared with the prior art, the technical advantages of the present invention are as follows: High treatment stability: Through fractional desalination, pre-oxidation and detoxification, multi-stage biochemical treatment, and terminal deep oxidation with multiple barriers, it can adapt to huge water quality fluctuations in optoelectronic and pharmaceutical intermediate wastewater, and has operated continuously for 3 months without exceeding the standard. The nitrogen removal efficiency is significantly improved: the total nitrogen removal rate of conventional single-stage AO is ≤60%, while the total nitrogen removal rate of this process is ≥95%, the ammonia nitrogen removal rate is ≥98%, and the total nitrogen is stably controlled at ≤20mg / L; Operating costs are significantly reduced: Compared with the traditional "full-volume Fenton + single-stage AO" process, aeration energy consumption is reduced by 20%, acid and alkali reagent consumption is reduced by 40%, and the cost per ton of water treated is reduced by 15 to 20 yuan. Complete supporting environmental protection units: simultaneous design of waste gas collection and purification, sludge dewatering and hazardous waste disposal, no risk of secondary pollution, and strong adaptability for industrialization. With a wide range of adjustable process parameters and flexible equipment layout, it can be adapted to optoelectronic and pharmaceutical intermediate production lines of different scales from 100 to 1000 m³ / d. Attached Figure Description

[0010] Figure 1 is a process flow diagram of the present invention; Figure 2 is a diagram of the two-stage AO of the present invention (clearly showing the segmented water inlet and mixed liquor return path).

[0011] The system includes: 1 - High-salt wastewater tank; 2 - First coagulation sedimentation tank; 3 - Low-temperature vacuum evaporation system; 4 - High-concentration wastewater tank; 5 - Second coagulation sedimentation tank; 6 - Micro-electrolysis-Fenton coupled reaction tank; 7 - First neutralization sedimentation tank; 8 - Comprehensive equalization tank; 8a - Water collection well; 9 - Hydrolysis acidification tank; 10 - Anaerobic reactor; 10a - Biogas desulfurization system; 11 - Primary AO tank; 11-1 - First anoxic tank; 11-2 - First aerobic tank; 12 - Secondary AO tank; 12-1 - Second anoxic tank; 12-2 - Second aerobic tank; 13 - Secondary sedimentation tank; 14 - Terminal Fenton oxidation tank; 15 - Second neutralization sedimentation tank; 16 - Clear water tank; 17 - Sludge tank; 18 - Dewatering machine; 19 - Two-stage spray tower; 20 - Biological filter; 21 - ... Exhaust fan; all odor-generating tanks are equipped with sealed gas collection pipelines connected to 19 two-stage spray towers. Detailed Implementation

[0012] The specific implementation of the present invention will be described in detail below with reference to examples and specific circumstances.

[0013] The present invention is illustrated by the following embodiments: A method for the deep treatment of wastewater from optoelectronic pharmaceutical intermediates, with a treatment capacity of 300 m³ / d, an hourly treatment rate of 12.5 m³ / h, and continuous operation for 24 hours; the influent is high-salinity wastewater with a salinity of 100,000–158,000 mg / L and high-concentration wastewater with a COD of 5,553–105,600 mg / L. The steps are as follows: S1. Classified collection: High-salt wastewater is stored separately in the high-salt wastewater tank (1). After the washing wastewater passes through a 5mm screen to intercept large particles of impurities, it is collected as high-concentration, non-degradable wastewater in the high-concentration wastewater tank (4). Domestic sewage from the factory area is intercepted by a 10mm screen and then collected in the collection well (8a). S2. Differentiated and targeted preprocessing: S21. Pretreatment of high-salt wastewater: Pump the high-salt wastewater into the first coagulation sedimentation tank (2), add 30% sulfuric acid or 50% sodium hydroxide to adjust the pH to 7.0-7.5, add 25mg / L PAC with a stirring speed of 80-120r / min, add 0.8mg / L PAM with a stirring speed of 30-50r / min, and react for 15min to carry out coagulation, flocculation and mud-water separation. The supernatant enters the low-temperature evaporation system (3), with an evaporation temperature of 45℃, a vacuum degree of 0.09Mpa, and a desalination rate of ≥95%. The condensate is discharged into the high-concentration wastewater tank (4). S22, Coupling oxidation of high-concentration, recalcitrant wastewater: The mixed wastewater in the high-concentration wastewater tank (4) is pumped into the second coagulation sedimentation tank (5), acid / alkali is added to adjust the pH to 7.0-7.5, PAC 30mg / L and PAM 1.0mg / L are added, the reaction is stirred for 20min, and the supernatant after mud-water separation enters the micro-electrolysis-Fenton reaction tank (6); the micro-electrolysis-Fenton reaction tank (6) is filled with iron-carbon packing material, the iron-carbon mass ratio is 2:1, the packing layer height is 1.8m, sulfuric acid with a volume concentration of 30% is added to adjust the pH to 3.0, ferrous sulfate 100mg / L and 30% hydrogen peroxide 1500mg / L are added, the bottom micropores are aerated, the aeration intensity is 0.8m³ / (m²・h), the micro-electrolysis reaction is carried out for 30min first, and then the Fenton oxidation reaction is carried out for 45min; after the reaction, the wastewater enters the first neutralization sedimentation tank (7), 50% sodium hydroxide is added to adjust the pH. When the temperature reaches 7.0-7.5, add 0.5 mg / L of PAM and allow it to settle for 120 minutes to achieve mud-water separation. S3. Comprehensive regulation: The domestic sewage from the collection well (8a) and the effluent from the first neutralization sedimentation tank (7) are sent to the comprehensive regulation tank (8), with an effective volume of 300m³ and a maximum hydraulic retention time of 24h. Water quality homogenization and water quantity homogenization are carried out, and pre-aeration is carried out at the same time with an aeration intensity of 0.3m³ / (m²・h). The salinity of the mixed wastewater is ≤5000mg / L. S4. Biochemical pretreatment: The wastewater after comprehensive adjustment is sent to the hydrolysis acidification tank (9), with an effective volume of 150m³. The tank is equipped with combined packing material with a filling rate of 60% and a hydraulic retention time of 12h. Under the anoxic conditions of dissolved oxygen ≤0.5mg / L, the large molecular recalcitrant organic matter is converted into small molecular easily degradable organic matter, and the wastewater B / C ratio is increased from 0.2-0.25 to 0.35-0.4. S5. Anaerobic Degradation: The hydrolyzed and acidified wastewater is pumped into a UASB anaerobic reactor (10) with an effective volume of 500 m³, a volumetric loading of 3 kg COD / (m³・d), and a hydraulic retention time of 40 h. A high-concentration sludge bed is formed at the bottom with a sludge concentration of 30-50 g / L. Most of the organic pollutants in the wastewater are degraded into methane and carbon dioxide through anaerobic fermentation. A three-phase separator is installed at the top of the reactor. The digested gas is desulfurized by the desulfurization system (10a) and then flared for combustion. The COD removal rate is over 80%. The digested liquid is discharged in stages, and the sludge particles settle and are returned to the sludge bed. S6. Two-stage AO segmented denitrification: The digestate from the anaerobic reactor (10) is sent in segments to the primary AO tank (11) and the secondary AO tank (12) at a ratio of 8:2. The effective volume of the primary AO tank (11) is 300 m³, of which the first anoxic tank (11-1) is 75 m³ and the first aerobic tank (11-2) is 225 m³; the secondary AO... The effective volume of pool (12) is 150 m³, of which the second anoxic pool (12-1) is 75 m³ and the second aerobic pool (12-2) is 75 m³. Both the first anoxic pool (11-1) and the second anoxic pool (12-1) are equipped with submersible mixing devices to enhance the mixing of influent, nitrified liquid and returned sludge. At the same time, porous suspended packing is added to both anoxic pools to provide a carrier for anaerobic ammonia oxidizing bacteria. Both the first aerobic pool (11-2) and the second aerobic pool (12-2) are equipped with microporous aeration devices with an aeration intensity of 1.5 m³ / (m²・h) to maintain a dissolved oxygen concentration of 2-4 mg / L. At the same time, porous suspended packing is added to both aerobic pools to provide a carrier for anaerobic ammonia oxidizing bacteria. The mixed liquid of the first aerobic pool (12-2) is returned to the first anoxic pool (11-1) with a return ratio of 200%. The mixed liquor from the second aerobic tank (12-2) is recycled to the second anoxic tank (12-1) at a recycling rate of 100%. The effluent from the first aerobic tank (11-2) is connected to the second anoxic tank (12-1). In the anoxic tank, denitrifying bacteria in the sludge can directly utilize carbon sources to perform traditional denitrification, converting nitrate nitrogen in the influent, recycled sludge, and recycled nitrified liquor into nitrogen gas. Meanwhile, denitrifying bacteria in the suspended packing biofilm perform short-cut denitrification, reducing nitrate nitrogen in the influent, recycled sludge, and recycled nitrified liquor to nitrite nitrogen. Anaerobic ammonia oxidizing bacteria on the suspended packing biofilm convert nitrite nitrogen and ammonia nitrogen into nitrogen gas. In the aerobic tank, ammonia oxidizing bacteria and nitrite oxidizing bacteria oxidize the remaining ammonia nitrogen in the wastewater into nitrate nitrogen, ultimately achieving the coupling of traditional denitrification and short-cut denitrification with anaerobic ammonia-oxygen denitrification, achieving a total nitrogen removal rate of over 95%. S7. Solid-liquid separation: The effluent from the secondary AO tank (12) is sent to the secondary sedimentation tank (13) with an effective volume of 90 m³ and a surface loading of 0.7 m³ / (m²·h). The sedimentation time is 180 min to separate the sludge from the treated water. The sludge return ratio is 50%. S8. Deep oxidation: The effluent from the secondary sedimentation tank (13) is sent to the Fenton oxidation tank (14) with an effective volume of 20m³. 30% sulfuric acid is added to adjust the pH to 3.0. 40mg / L of ferrous sulfate and 200mg / L of 30% hydrogen peroxide are added. The mixture is stirred and reacted for 60min to degrade the residual recalcitrant organic matter. The net COD removal is ≥40mg / L. S9, Neutralization and Sedimentation: The wastewater after Fenton oxidation is sent to the second neutralization and sedimentation tank (15), with an effective volume of 60m³. 50% sodium hydroxide is added to adjust the pH to 7.0-7.5. PAC 15mg / L and PAM 0.3mg / L are added. After stirring and reacting for 15min, sedimentation is carried out for 90min to achieve mud-water separation. S10, Standard Discharge: The supernatant from the second neutralization sedimentation tank (15) enters the clear water tank (16), with an effective volume of 100m³. After testing, the effluent from the clear water tank (16) shows the following: COD 152mg / L, ammonia nitrogen 0.5mg / L, total nitrogen 32mg / L, and total phosphorus 1.0mg / L. The effluent meets the standard and is discharged after meeting the standard. S11. Centralized treatment of waste gas: high-salt wastewater pool, high-concentration wastewater pool, comprehensive regulating pool, hydrolysis acidification pool, anaerobic reactor, sludge pool, sludge dewatering and sealed gas collection, waste gas sequentially passes through two-stage spray towers, first-stage alkaline washing, second-stage acid washing, activated carbon-microbial composite packing biological filter for degradation, exhaust by induced draft fan to eliminate organic odor in the plant area. S12. Unified disposal of sludge: All sludge generated from each coagulation sedimentation unit, hydrolysis acidification, and anaerobic reactor is discharged into the sludge tank, dewatered by plate and frame dewatering, and the moisture content of the dewatered sludge is ≤80%; the dewatered filtrate is returned to the integrated equalization tank for repeated treatment; dewatered sludge and evaporation crystallization salt residue are both hazardous wastes and are disposed of in compliance with regulations by outsourcing.

[0014] To ensure effectiveness and meet environmental requirements: The waste gas generated by the high-salt wastewater tank (1), high-concentration wastewater tank (4), integrated regulating tank (8), hydrolysis acidification tank (9), sludge tank (17) and dewatering machine (18) is collected through the exhaust pipe and then sequentially enters the two-stage spray tower (19) (first stage alkaline spray, second stage acid spray) for spray absorption and the biological filter (20), which is filled with activated carbon-microorganism composite packing material for microbial oxidation treatment. Finally, it is guided by the induced draft fan (21) to meet the emission standards. The sludge produced by the first coagulation sedimentation tank (2), the second coagulation sedimentation tank (5), the first neutralization sedimentation tank (7), the hydrolysis acidification tank (9), the anaerobic reactor (10) and the second neutralization sedimentation tank (15) enters the sludge tank (17) through the sludge discharge pipe. The effective volume is 100m³. The filtrate after being dewatered by the plate and frame dewatering machine (18) (sludge moisture content ≤80%) is returned to the comprehensive regulating tank (8) for reuse. The dewatered sludge is disposed of by an external contractor. The sludge produced in the secondary sedimentation tank (13) is divided into two parts: the remaining sludge is discharged into the sludge tank (17), and the sludge-water mixture is returned to the first anoxic tank (11-1) of the primary AO tank (11), with a return ratio of 50%, maintaining the sludge concentration in the tank at 3-5 g / L.

[0015] This invention has been tested and applied in the field. For example, when used in a certain optoelectronic pharmaceutical intermediate production enterprise, the treated water has consistently met the standards for 3 consecutive months without any water quality exceeding the standards. Moreover, the operating cost per ton of water is reduced by 18 yuan compared with the traditional process, which has significant economic and environmental benefits. Compared with the existing technology, it has the following outstanding beneficial effects: (1) It specifically solves the problem of synergistic treatment of high salt and high concentration difficult degradation: Through the classification pretreatment of "high salt wastewater evaporation desalination + high concentration wastewater micro-electrolysis-Fenton coupled oxidation", the salt concentration of the subsequent biochemical system is controlled at 5000 mg / L. The following improvements are achieved: (1) The removal rate of recalcitrant organic matter is increased to over 70%, avoiding salt inhibition and biotoxicity inhibition; (2) The denitrification efficiency is significantly improved: the two-stage AO segmented influent + internal reflux design is adopted, the total nitrogen removal rate reaches over 95%, and the ammonia nitrogen removal rate reaches over 98%, which is far superior to the conventional AO process (total nitrogen removal rate ≤ 60%); (3) The operating cost is optimized: the classification pretreatment reduces the waste of reagents, and the two-stage AO process saves 20% of aeration energy consumption and 40% of alkali consumption compared with the traditional process, reducing the operating cost per ton of water by 15-20 yuan; (4) The operation stability is strong: through the whole process design of "pretreatment detoxification and desalination + deep biochemical degradation + deep oxidation bottom-line", it has strong resistance to water quality and quantity shocks and can adapt to the water quality fluctuation characteristics of the production of optoelectronic pharmaceutical intermediates. It is a major innovation in the treatment of wastewater from optoelectronic pharmaceutical intermediates and has practical application value.

Claims

1. A method for deep treatment of wastewater from optoelectronic pharmaceutical intermediates, characterized in that, This method is suitable for wastewater with a salt content of 100,000–158,000 mg / L, raw water COD of 5,553–105,600 mg / L, and containing aniline, halogenated aromatic hydrocarbons, and highly toxic and recalcitrant photoelectric and pharmaceutical intermediates. It includes the following steps: S1. Classified collection: High-salt wastewater generated by the production process is collected in a high-salt wastewater pool (1). Equipment and floor cleaning wastewater is collected in a high-concentration wastewater pool (4) after removing large particulate impurities by a screen. Domestic sewage in the factory area is collected in a collection well (8a) after pretreatment by a screen. S2. Differentiated and targeted preprocessing: S21. High-salt wastewater desalination pretreatment: The high-salt wastewater is pumped into the first coagulation sedimentation tank (2), the pH is adjusted to 6.5-8.5, PAC and PAM are added for coagulation sedimentation to separate suspended solids, and the supernatant is sent to the low-temperature vacuum evaporation system (3) for desalination. The desalination rate is ≥95%, the removal rate of macromolecular organic matter is ≥90%, and the evaporation condensate is discharged into the high-concentration wastewater tank (4) to mix with the high-concentration recalcitrant wastewater. S22, Pretreatment of high-concentration, recalcitrant wastewater coupled with oxidation: The mixed wastewater in the high-concentration wastewater tank (4) is sent to the second coagulation sedimentation tank (5), the pH is adjusted to 6.5-8.5, PAC and PAM are added to coagulate and precipitate the suspended solids, the supernatant enters the micro-electrolysis-Fenton coupled reaction tank (6), the pH is adjusted to 2.5-3.5 by adding acid, ferrous salt and hydrogen peroxide are added and aerated, and the galvanic cell oxidation + hydroxyl radical deep detoxification is carried out. The reaction effluent enters the first neutralization sedimentation tank (7), the pH is adjusted to 6.5-8.5 by adding alkali and PAM to achieve mud-water separation; S3, Comprehensive homogenization and regulation: The domestic sewage from the collection well (8a) and the effluent from the first neutralization sedimentation tank (7) are sent to the comprehensive regulation tank (8) for homogenization and equalization and pre-aeration to buffer the impact of water quality and quantity. S4. Biochemical pretreatment: The wastewater after comprehensive adjustment is sent to the hydrolysis acidification tank (9) to break down large molecular toxic organic matter under anaerobic conditions and improve the biodegradability of wastewater B / C. S5. Anaerobic deep degradation: The hydrolyzed and acidified wastewater is pumped into the anaerobic reactor (10), where most of the organic matter is degraded by anaerobic microorganisms, achieving three-phase separation of digestion gas, digestion liquid and sludge particles. S6. Segmented Influent Two-Stage AO Coupled Deep Denitrification: The digestate from the anaerobic reactor (10) is segmented and fed into the primary AO tank (11) and the secondary AO tank (12). The primary AO tank (11) includes a first anoxic tank (11-1) and a first aerobic tank (11-2) connected in sequence. The mixed liquor from the first aerobic tank (11-2) is returned to the first anoxic tank (11-1). The secondary AO tank (12) includes a second anoxic tank (12-1) and a second aerobic tank (12-2) connected in sequence. 2) The mixed liquor from the second aerobic tank (12-2) is recycled to the second anoxic tank (12-1), and the effluent from the first aerobic tank (11-2) is connected to the second anoxic tank (12-1). Suspended biological packing is added to both the anoxic and aerobic tanks. The biofilm of the packing simultaneously enriches denitrifying bacteria, short-cut denitrifying bacteria, and anaerobic ammonia oxidizing bacteria, realizing the synergistic nitrogen removal through multiple pathways of traditional nitrification-denitrification, short-cut denitrification coupled with anaerobic ammonia oxidation. Microporous aeration is set in both aerobic tanks to maintain dissolved oxygen at 2-4 mg / L. S7. Secondary sedimentation solid-liquid separation: The effluent from the secondary AO tank (12) is sent to the secondary sedimentation tank (13) for sludge-water separation; the secondary sedimentation sludge is divided into two streams, one stream of sludge is returned to the first anoxic tank of the primary AO tank, and the remaining sludge is discharged into the sludge tank. S8. Deep oxidation: The effluent from the secondary sedimentation tank (13) is sent to the Fenton oxidation tank (14), acid is added to adjust the pH to 2.5-3.5, ferrous salt and hydrogen peroxide are added to carry out Fenton oxidation to remove residual recalcitrant organic matter. S9, Neutralization and sedimentation: The wastewater after Fenton oxidation is sent to the second neutralization and sedimentation tank (15), and alkali is added to adjust the pH to 6.5-8.

5. PAC and PAM are added to carry out coagulation and sedimentation to remove the suspended solids and organic intermediates produced by oxidation. S10, Standard Discharge: The supernatant from the second neutralization sedimentation tank (15) enters the clear water tank (16) and is discharged after passing the test; S11. Centralized treatment of waste gas: high-salt wastewater tank, high-concentration wastewater tank, integrated equalization tank, hydrolysis acidification tank, anaerobic reactor, sludge tank, sludge dewatering tank and closed gas collection. The waste gas is treated by two-stage spray tower and biological filter in sequence and then discharged in compliance with the emission standards. S12. Unified disposal of sludge: All sludge generated from each coagulation sedimentation unit, hydrolysis acidification, and anaerobic reactor is discharged into the sludge tank, dewatered by plate and frame dewatering, and the dewatered filtrate is returned to the integrated equalization tank for repeated treatment. Dewatered sludge and evaporation crystallization salt residue are disposed of as hazardous waste in compliance with regulations by outsourcing.

2. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, In step S21, the PAC dosage in the first coagulation sedimentation tank (2) is 25 mg / L and the PAM dosage is 0.8 mg / L; in step S22, the PAC dosage in the second coagulation sedimentation tank (5) is 30 mg / L and the PAM dosage is 1.0 mg / L, and the PAM dosage in the first neutralization sedimentation tank (7) is 0.5 mg / L; in step S8, the ferrous sulfate dosage is 40 mg / L and the 30% hydrogen peroxide dosage is 200 mg / L; in step S9, the PAC dosage is 15 mg / L and the PAM dosage is 0.3 mg / L.

3. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, The waste gas generated by the high-salt wastewater tank (1), high-concentration wastewater tank (4), integrated regulating tank (8), hydrolysis acidification tank (9), sludge tank (17) and dewatering machine (18) is collected through the exhaust pipe and then sequentially enters the two-stage spray tower (19) for spray absorption and the biological filter (20) for microbial oxidation treatment. Finally, it is guided by the induced draft fan (21) to meet the emission standards.

4. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, The sludge produced by the first coagulation sedimentation tank (2), the second coagulation sedimentation tank (5), the first neutralization sedimentation tank (7), the hydrolysis acidification tank (9), the anaerobic reactor (10) and the second neutralization sedimentation tank (15) enters the sludge tank (17) through the sludge discharge pipe. The filtrate after dewatering by the dewatering machine (18) is returned to the comprehensive regulating tank (8) for reuse, and the dewatered sludge is disposed of by an external party. The sludge produced by the secondary sedimentation tank (13) is divided into two parts: the remaining sludge is discharged into the sludge tank (17), and the mud-water mixture is returned to the first anoxic tank (11-1) of the primary AO tank (11).

5. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, The first aerobic tank (11-2) of the primary AO tank (11) and the second aerobic tank (12-2) of the secondary AO tank (12) are both equipped with microporous aeration devices. The aeration intensity is controlled at 1.5 m³ / (m²・h) to maintain the dissolved oxygen concentration in the tank at 2-4 mg / L. Suspended packing is added to both the anoxic and aerobic tanks to provide a carrier for the attachment and proliferation of denitrifying bacteria and anaerobic ammonia oxidizing bacteria. The connecting holes of each tank are equipped with grids, and the suspended packing moves only in a single functional unit, which facilitates the enrichment of more functional microorganisms.

6. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, The operating conditions of the low-temperature vacuum evaporation system in step S21 are: evaporation temperature 45℃, vacuum degree 0.09MPa, and desalination rate of high-salt wastewater ≥95%.

7. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, In step S22, the micro-electrolysis-Fenton coupled reaction tank is filled with iron-carbon packing material with an iron-carbon mass ratio of 2:1 and a packing layer height of 1.8m. The micro-electrolysis reaction is held for 30 minutes, the Fenton oxidation is held for 45 minutes, and the aeration intensity at the bottom of the tank is 0.8m³ / (m²・h).

8. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, In step S4, the hydraulic retention time in the hydrolysis acidification tank is 12 hours, the dissolved oxygen is controlled to be ≤0.5mg / L, and the internal combined packing material filling rate is 60%.

9. The method for deep treatment of optoelectronic pharmaceutical intermediate wastewater according to claim 1, characterized in that, In step S5, the UASB anaerobic reactor has a volumetric loading rate of 3 kg COD / (m³・d), a hydraulic retention time of 40 h, and a sludge concentration of 30-50 g / L.

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