Quality-divided self-adaptive-multi-section synergistic strengthening photoresist wastewater treatment process

Abstract

The invention discloses a quality-divided self-adaptive-multi-section collaborative strengthening photoresist wastewater treatment process. The process comprises the following steps: quality-divided self-adaptive shunting, self-adaptive Fenton oxidation pretreatment, collaborative biochemical degradation treatment and self-adaptive deep strengthening treatment. According to the invention, salt content and COD two-parameter multi-threshold quality-divided self-adaptive shunting, Fenton oxidation parameter dynamic adjustment, up-flow dynamic water distribution hydrolytic acidification, anaerobic intelligent nutrition regulation and EGSB anaerobic cooperation, A / O biochemical and self-adaptive precipitation enhanced advanced treatment, and environment-friendly compliance treatment of sludge, concentrated salt and biogas are carried out through a whole-process PLC cooperative regulation and control system; a set of cooperative treatment system adaptive to variable photoresist wastewater types and large water quality fluctuation is constructed, efficient detoxification and bond breaking of high-salt, high-chlorine and high-COD toxic wastewater are achieved, the biodegradability is remarkably improved, COD is degraded in a stepped mode, effluent stably reaches the standard, and it is ensured that by-products are treated in a compliant mode and the operation cost is low.

Description

A quality-adaptive, multi-segment synergistic enhancement process for photoresist wastewater treatment Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a fractional adaptive-multi-stage synergistic enhancement process for treating photoresist wastewater. Background Technology

[0002] Photoresist wastewater is a typical and difficult-to-treat industrial wastewater generated by advanced manufacturing industries such as semiconductor chip, display panel, and resin production. Its main characteristics include complex and highly fluctuating water composition, with salt content varying widely from 4% to 40%, and chemical oxygen demand (COD) concentrations ranging from tens of milligrams per liter to hundreds of thousands of milligrams per liter. This type of wastewater generally exhibits extremely poor biodegradability (B / C ratio typically below 0.2), contains biologically inhibitory or toxic organic matter, has large pH fluctuations, and is often accompanied by high concentrations of chloride ions, making it difficult to treat directly and effectively using conventional biological processes.

[0003] Currently, common treatment processes for this type of wastewater often employ a combination of fixed-flow diversion, single oxidation, and conventional biological treatment. In the diversion stage, classification is typically based only on conductivity or a single salinity index, failing to precisely differentiate between different wastewater subtypes such as high-salt, high-COD, high-salt, low-COD, and low-salt, high-toxicity wastewater. This leads to extreme water quality being mistakenly placed in unsuitable treatment units, causing system shocks. In the pretreatment stage, the dosage ratios and reaction times of advanced oxidation technologies are often fixed, making dynamic optimization based on real-time changes in influent COD concentration and toxicity levels difficult. This results in either insufficient oxidation, leaving toxic residues that negatively impact subsequent biological treatment, or excessive oxidation, leading to reagent waste and increased operating costs. In the core biological treatment unit, the high-salt environment significantly inhibits microorganisms, especially methanogens; simultaneously, the influent nutrient ratios are often based on experience, failing to precisely match the fluctuating water quality, resulting in unstable degradation efficiency and weak shock resistance in the anaerobic system. Furthermore, intermediate units such as hydrolysis and acidification generally suffer from a single water distribution method and are prone to hydraulic short-circuiting or dead zones, limiting their effectiveness in improving the biodegradability of wastewater. Advanced treatment processes largely rely on fixed coagulation and sedimentation techniques, lacking the adaptive capability to enhance processes based on fluctuations in effluent quality.

[0004] In summary, existing technologies for treating photoresist wastewater with variable composition, high salt content, and high toxicity suffer from the following main shortcomings: the separation and diversion mechanisms are crude, failing to accurately identify wastewater subtypes and optimize pathways; the operating parameters of each core treatment unit (especially the advanced oxidation and biochemical stages) are rigid, lacking adaptive adjustment capabilities to fluctuations in influent water quality; unit processes often operate in isolation, lacking coordinated and linked control based on water quality parameters; and there is insufficient consideration for the systematic and compliant disposal of high-chlorine byproducts, concentrated salts, sludge, and biogas generated during the treatment process. These deficiencies collectively result in low overall treatment efficiency, poor effluent quality stability, uncontrollable operating costs, and the risk of secondary pollution. Therefore, there is an urgent need to develop a highly efficient treatment process that can adapt to the highly volatile characteristics of photoresist wastewater, achieve intelligent coordination and adaptive parameter optimization among treatment units, and ensure environmental compliance throughout the entire process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a differentiated adaptive-multi-stage synergistic enhancement process for photoresist wastewater treatment. This process utilizes a dual-parameter multi-threshold differentiated adaptive diversion based on salinity and COD, dynamic adjustment of Fenton oxidation parameters, upflow dynamic water distribution for hydrolysis and acidification, anaerobic intelligent nutrient regulation combined with EGSB anaerobic treatment, A / O biochemical treatment combined with adaptive sedimentation for enhanced deep treatment, environmentally compliant disposal of sludge, concentrated salt, and biogas, and a full-process PLC synergistic control system. This constructs a synergistic treatment system adaptable to the diverse types and fluctuating water quality of photoresist wastewater. It achieves efficient detoxification and bond breaking of high-salt, high-chlorine, and high-COD toxic wastewater, significantly improved biodegradability, stepwise COD degradation, and stable effluent compliance, while ensuring compliant disposal of byproducts and low operating costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A differentiated adaptive-multi-stage synergistic enhancement process for treating photoresist wastewater includes the following steps: S1, Differentiated adaptive diversion: Online monitoring of the photoresist wastewater to obtain real-time salinity and chemical oxygen demand (COD) data; Based on a dual-parameter criterion composed of salinity and COD data, the wastewater is automatically diverted to four different pretreatment paths, including a resource recovery treatment path, an evaporation desalination treatment path, an enhanced pretreatment path, and a direct biological discharge treatment path; S2, Fenton oxidation pretreatment: Fenton oxidation treatment is performed on the wastewater diverted to the enhanced pretreatment path, based on the influent COD concentration... S3, Biochemical Degradation Treatment: Wastewater pretreated by Fenton oxidation is mixed with wastewater from the direct biochemical discharge treatment path after homogenization and conditioning. The mixed wastewater is then subjected to hydrolysis acidification, anaerobic biological treatment, and A / O aerobic biological treatment in sequence. S4, Deep Enhanced Treatment: The effluent from the A / O aerobic biological treatment is monitored. Based on the real-time effluent quality, the system automatically switches between coagulation mode and coagulation adsorption enhancement mode and adjusts the dosage of adsorbent material to ensure that the final effluent consistently meets the standards.

[0008] Preferably, in step S1, the specific method for diverting waste based on salinity and COD data is as follows:

[0009] (1): When the influent COD > 100000 mg / L, the wastewater is diverted to the resource recovery and treatment path for source interception and directed to the solvent recovery or incineration unit;

[0010] (2) When the influent COD ≤ 100000 mg / L does not meet the conditions and the influent salinity ≥ 8%, the wastewater is diverted to the evaporation desalination treatment path and pre-oxidation and MVR forced circulation evaporation treatment are performed;

[0011] (3) When the influent COD≤100000 mg / L does not meet the condition, and the influent salinity is 2%-8% or the influent 5000<COD≤100000 mg / L and salinity<2% and COD>5000 mg / L, the wastewater is diverted to the enhanced pretreatment path and Fenton oxidation pretreatment is performed.

[0012] (4) When the influent salinity is <2% and COD ≤5000 mg / L, the wastewater is diverted to the direct biological discharge treatment path and directed to the biological equalization tank for homogenization and dilution.

[0013] Preferably, in step S2, the adaptive switching of the Fenton oxidation dosing mode follows the principle of "toxicity control first", specifically: (1) High-intensity oxidation mode: when the online monitoring toxicity inhibition rate is >50%, or the toxicity inhibition rate is ≤50% and the influent COD is >50000 mg / L, this mode is forcibly started. At this time, the mass ratio of H2O2 to COD is 0.4-0.47, the reaction time is 45-60 min, and the primary goal is to break the toxic bonds; (2) Standard enhanced mode: when the influent toxicity inhibition rate is ≤50% and 10000 mg / L < COD ≤ 50000 mg / L, it is started, and the mass ratio of H2O2 to COD is 0.3-0.4; (3) Low-consumption conditioning mode: when the influent toxicity inhibition rate is ≤50% and COD ≤ 10000 mg / L, the mass ratio of H2O2 to COD is 0.2-0.3, and the operation is mainly low-consumption.

[0014] Preferably, in step S2, according to H2O2 / Fe 2+ Ferrous iron was added to the system in a molar ratio of 3:1 to 4:1; the pH of the reaction system was 3.0 to 3.5.

[0015] Preferably, in step S3, before the hydrolysis acidification treatment, an anaerobic nutrient regulation step is also included: based on the COD, total nitrogen, and total phosphorus concentrations of the Fenton oxidation treatment effluent, nitrogen and phosphorus sources are added in a ratio of COD:TN:TP = 100:(3-5):(1-1.5), and a trace element mixture is added. The dosage of the trace element mixture is 0.01-0.03 g / L, including Fe in a mass ratio of 5:1:1:0.5. 2+ Co 2+ Ni 2+ and Mo 6+ .

[0016] Preferably, the nitrogen and phosphorus sources are added as follows: when the total nitrogen concentration in the wastewater is ≥3 mg / L, the addition of nitrogen source is reduced or stopped; when the total nitrogen concentration in the wastewater is <3 mg / L and COD >50000 mg / L, the nitrogen source is added at the upper limit; when the total phosphorus concentration in the wastewater is <1 mg / L, potassium dihydrogen phosphate is added to supplement it.

[0017] Preferably, in step S3, the hydrolysis acidification treatment adopts an upflow dynamic water distribution method. The orifice diameter of the water distributor is adjusted to 5-8 mm by monitoring the influent flow rate, the water distribution pressure is 0.1-0.3 MPa, the upflow velocity in the pool is 0.5-1.2 m / h, and the sludge concentration in the pool is 15-30 g / L.

[0018] Preferably, in step S3, the anaerobic biological treatment uses an expanded granular sludge bed (EGSB) reactor, inoculated with salt-tolerant anaerobic granular sludge, and 0.1-0.3 g / L of alkalinity regulator is added to maintain an alkalinity of 2000-3000 mg / L.

[0019] Preferably, in step S4, the adaptive deep enhancement treatment uses an activated carbon dosing device. When the online monitoring shows that the COD of the secondary sedimentation tank effluent is >50 mg / L or SS is >5 mg / L, the activated carbon adsorption mode is automatically started, the amount of activated adsorption material added is 30-150 mg / L, and solid-liquid separation is carried out through the inclined tube sedimentation tank, and the supernatant is taken as the final effluent.

[0020] Preferably, the condensate generated in the evaporation desalination process is equipped with an online secondary discrimination branch: when the online COD of the condensate is >5000mg / L, the condensate is forcibly switched to the front end of the Fenton oxidation unit in the yellow zone for downgrade secondary treatment.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) This invention treats extremely high concentration organic waste liquid (red zone) as solvent resources rather than wastewater and directly intercepts and incinerates it at the source; high salt and highly toxic wastewater (orange zone) is separated into clean condensate by MVR evaporation and reused; medium and high concentration wastewater (yellow zone) and low concentration wastewater (green zone) are intelligently proportioned; the four-level quality-adaptive diversion system based on the salt content + COD dual parameter matrix of this invention fundamentally solves the problem of repeated collapse of the biochemical system caused by the complex and variable composition of photoresist wastewater, and realizes the inherent safety and continuous stable operation of the process;

[0023] (2) The front-end adaptive Fenton system of the present invention can automatically switch modes according to the toxicity and load of the influent, which not only ensures the low-toxicity environment required for the survival of subsequent anaerobic bacteria, but also avoids the waste of reagents; the mid-end anaerobic system intelligently adds trace elements and nutrients by monitoring the carbon, nitrogen and phosphorus ratio in real time, and activates the methanogenic activity in the high-salt environment by combining salt-resistant acclimatization bacteria and alkalinity buffering strategy; the end-end deep treatment switches between coagulation and adsorption modes according to the effluent indicators; this parameter linkage of the whole process not only ensures the deep mineralization and standard discharge of high-salt and high-toxicity photoresist wastewater with extremely low energy consumption, but also realizes sludge reduction and closed-loop recycling of resources. Detailed Implementation

[0024] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0025] The main processing route of this invention is as follows:

[0026] Fenton influent mixing tank → Adaptive Fenton oxidation (dynamic parameter adjustment) → Neutralization degassing sedimentation tank → Anaerobic dosing tank (intelligent nutrient regulation) → Upflow dynamic water distribution hydrolysis acidification tank → EGSB anaerobic reactor (biogas recovery and treatment system) → A / O biochemical tank → Secondary sedimentation tank → Adaptive sedimentation enhancement system (can add activated carbon and other adsorption materials) → Final discharge tank (discharged after meeting standards).

[0027] The entire process is controlled by a PLC system that links multiple online monitoring instruments and actuators (valves, metering pumps, water distributors, etc.) to achieve automatic adjustment of process parameters and emergency response. The PLC collaborative control system adopts a hierarchical control architecture. The bottom layer is the data acquisition layer, which collects conductivity (representing salinity), COD, and biotoxicity data in real time through online sensors installed at the inlet of the equalization tank, the Fenton inlet, and the biological effluent outlet. The middle layer is the logic judgment layer, which has a built-in multi-threshold discrimination algorithm. The top layer is the execution layer. To eliminate the risks caused by instrument failure, the PLC system has fault-oriented safety logic: when the online COD or toxicity detectors have no signal output or the abnormal values ​​last for more than 5 minutes, the system automatically switches to the yellow zone - high oxidation mode, that is, it operates at the maximum dosage and triggers an audible and visual alarm to ensure that the biological system is not damaged in the extreme case of sensor failure.

[0028] The specific operation of the photoresist wastewater treatment process is as follows:

[0029] (1) Quality-based adaptive diversion:

[0030] After high-salinity wastewater enters the storage tank, its salinity and COD are monitored in real time by an online monitoring instrument, and the data is synchronously transmitted to the PLC control system for adaptive diversion based on water quality.

[0031] Primary diversion (red zone): COD>100000mg / L (salinity not considered) → source interception → solvent recovery / waste liquid incineration; to prevent extremely high concentrations of organic solvents from causing poisoning of the biochemical system, evaporator explosion or coking blockage.

[0032] Secondary diversion (orange zone): When the conditions of the red zone are not met and the influent salinity is ≥8%, the process is as follows: advanced oxidation (defoaming / anti-foaming) → MVR forced circulation evaporation → solid-liquid separation; after evaporation, the condensate is tested online for COD. If the COD is >5000mg / L, it flows into the third-level yellow zone Fenton pre-stage; if the COD is ≤5000mg / L, it flows into the fourth-level green zone biological conditioning tank, and the crystallized salt is discharged externally. Oxidation is used to prevent evaporation and scaling, and thermal separation of salts is used to convert non-biodegradable wastewater into biodegradable condensate.

[0033] Three-stage diversion (yellow zone): When the conditions of the red and orange zones are not met, and the influent salinity is 2%-8% or the influent salinity is <2% and COD >5000 mg / L, the wastewater → acid-base adjustment (adjust pH to 3-4) → Fenton influent mixing tank (detoxification / B / C enhancement) → EGSB anaerobic system (after degrading most of the COD, it enters the A / O biological treatment); Fenton is used to improve biodegradability, and EGSB is used to efficiently remove dissolved COD under salt-tolerant conditions.

[0034] Four-stage diversion (green zone): salinity <2% and COD ≤5000mg / L → homogenization adjustment → biological adjustment tank (used as dilution water to merge with the effluent from the secondary orange zone and the tertiary yellow zone); using low-concentration wastewater as a buffer resource, the high-salinity effluent is diluted proportionally to ensure that the salinity of the final aerobic tank is stable within the optimal range for microorganisms.

[0035] The above thresholds (such as 100,000 mg / L, 5,000 mg / L, 8%, 2%) are the specific values ​​of the preferred experimental group. In actual operation, they can be adjusted and set within the range of ±10%-20% according to the specific composition characteristics of the photoresist wastewater.

[0036] After the wastewater enters the storage tank, the pH is adjusted to 3-4 by an automatic acid / alkali addition device (to adapt to the subsequent Fenton reaction), and then enters the Fenton influent mixing tank after buffering.

[0037] (2) Adaptive Fenton oxidation pretreatment

[0038] After the wastewater in the mixing tank is homogenized, the online monitoring system provides real-time feedback on CODin and toxicity equivalent. The PLC control system identifies the operating conditions as high-intensity oxidation mode, standard enhanced mode, and low-consumption conditioning mode based on the characteristics of the influent load.

[0039] Instead of relying solely on quantitative COD dosage, the following two-way feedback control logic is implemented:

[0040] High-intensity oxidation mode: Under high load / high toxicity conditions (when the online monitoring toxicity inhibition rate is >50% (regardless of COD concentration), or when the toxicity inhibition rate is ≤50% and the influent COD is >50000 mg / L (measured by luminescent bacteria method or respiration rate method)), a strong oxidation bond-breaking mode is activated, preferentially destroying chromophores and long-chain toxic substances. The H2O2 / COD mass ratio is set to 0.4-0.47, and the reaction time is extended to 45-60 min. In this mode, maximizing COD removal rate is not the goal; instead, the reaction endpoint is set at a toxicity inhibition rate below 30%.

[0041] Standard Enhanced Mode: Under medium load conditions (executed when the conditions for high-intensity oxidation mode are not met (i.e., toxicity inhibition rate ≤ 50% and COD ≤ 50000 mg / L), and 10000 mg / L < COD ≤ 50000 mg / L), the B / C enhancement mode is activated to create conditions for subsequent EGSB. The H2O2 / COD mass ratio is set to 0.3-0.4, and the reaction time is 30-45 min. The goal is to increase the effluent B / C ratio to > 0.35.

[0042] Low-consumption conditioning mode: Under low-load conditions (when the influent toxicity inhibition rate is ≤50% and COD is ≤10000 mg / L), the economical operation mode is activated to avoid waste of reagents. The H2O2 / COD mass ratio is set to 0.2-0.3, and the reaction time is shortened to 20-30 min, with only low-intensity micro-oxidation to reduce operating costs.

[0043] Fe 2+ Linkage: Based on the real-time H2O2 dosage, the PLC automatically adjusts the H2O2 / Fe ratio. 2+ The molar ratio is dynamically adjusted from 3:1 to 4:1 to avoid excessive iron sludge.

[0044] pH steady-state control: The acid dosage is finely adjusted by ORP (oxidation-reduction potential) feedback to maintain the pH of the reaction system at the optimal state of 3.0-3.5.

[0045] After oxidation, the wastewater enters a neutralization, degassing, and sedimentation tank. Calcium hydroxide is automatically added to adjust the pH to 7-8, followed by the addition of anionic PAM (1-5 mg / L). The mixture is rapidly stirred (100-150 rpm) for 5 minutes, then slowly stirred (30-50 rpm) for 15 minutes. After flocculation and separation, the supernatant enters the subsequent unit. After Fenton oxidation and neutralization precipitation remove some heavy metals and calcium and magnesium ions, the salt content of the supernatant increases slightly, and it then enters a mixing and conditioning tank.

[0046] By dynamically adjusting the front-end Fenton parameters, the B / C ratio of the wastewater entering the subsequent EGSB anaerobic system is forced to be maintained above 0.35 and the toxicity is within the tolerance range. This solves the technical problem in traditional processes where insufficient front-end oxidation leads to the collapse of the anaerobic system or excessive oxidation leads to a surge in operating costs.

[0047] (3) Anaerobic intelligent nutrient regulation treatment

[0048] The Fenton effluent enters the dosing tank, where the pH is adjusted to 7.0-7.8 and the temperature to 30-35℃ by adding sodium hydroxide / sulfuric acid. Homogenization is achieved through mechanical stirring (50-80 r / min). Influent COD, total nitrogen, and total phosphorus are monitored online, and nutrient dosage is dynamically calculated based on a C:N:P ratio of 100:(3-5):(1-1.5).

[0049] When the total nitrogen in the wastewater is ≥3mg / L, reduce or stop adding nitrogen sources;

[0050] When total nitrogen is <3 mg / L and COD >50000 mg / L, add nitrogen source at the upper limit.

[0051] When total phosphorus is <1 mg / L, potassium dihydrogen phosphate should be added to supplement it;

[0052] Simultaneously supplement with a 0.01-0.03 g / L trace element mixture (composed of Fe). 2+ Co 2+ Ni 2+ Mo 6+ The ratio of Fe to other trace elements in the mixture was 5:1:1:0.5, maintaining the concentration of each trace element in the reactor mixture at 5 mg / L. 2+ 1 mg / L Co 2+ 1 mg / L Ni 2+ 0.5 mg / L Mo 6+ The dosage is adjusted continuously based on the concentration of trace elements in the effluent.

[0053] (4) Upflow dynamic water distribution hydrolysis acidification treatment:

[0054] The effluent from the anaerobic dosing tank is pumped into the upflow dynamic water distribution hydrolysis acidification tank. A flow sensor monitors the influent flow rate in real time with an accuracy of ±5%. When the flow rate fluctuates by ±20%, the orifice diameter (5-8mm) and water distribution pressure (0.1-0.3MPa) of the water distributor are automatically adjusted to maintain an upflow velocity of 0.9m / h. The sludge concentration in the tank is maintained at 5-8g / L. A sludge return pump returns some of the sludge from the bottom of the tank to the influent end (return ratio 30-50%) to prevent sludge loss. The hydraulic retention time is 12h. Under the action of facultative anaerobic bacteria, macromolecular organic matter is decomposed into small molecule organic acids, and the B / C ratio is increased to above 0.35. The effluent then enters the EGSB anaerobic reactor.

[0055] The water distribution parameters (orifice size, pressure) are linked with the influent flow rate in real time. Combined with sludge recirculation, this ensures that hydrolysis acidification maintains efficient mass transfer and stable sludge concentration even under flow fluctuations, thereby achieving a stable improvement in biodegradability.

[0056] (5) Anaerobic treatment with EGSB

[0057] The effluent from the hydrolysis acidification tank enters the EGSB anaerobic reactor. The EGSB reactor is inoculated with salt-tolerant anaerobic granular sludge (acclimated to a salinity gradient of 0-6%), which possesses the ability to maintain high methanogenic activity under high salinity conditions. Alkalinity is maintained at 2000-3000 mg / L (calculated as CaCO3) by adding NaHCO3 (0.1-0.3 g / L) to buffer salinity and VFA fluctuations. The reactor upflow velocity is controlled at 2-3 m / h, and mass transfer is enhanced through biogas stirring, stabilizing the volumetric loading at 3.5 kg COD / m³. 3 The biogas produced is collected by a three-phase separator and then sequentially enters a dry desulfurization tower (desulfurizing agent: iron oxide, desulfurization efficiency ≥95%), a condensation and dehydration device (biogas moisture content ≤1% after dehydration), and a pressure stabilizing tank (pressure 0.05-0.1MPa). After passing the explosion-proof test, it is disposed of by flare incineration or combustion power generation. The reactor effluent (supernatant) enters the A / O biochemical tank, and part of the granular sludge at the bottom of the tank is returned to the front end of the reactor (return ratio 20%) to maintain the sludge concentration.

[0058] This invention utilizes salt-tolerant anaerobic granular sludge acclimated to a specific salinity gradient (0-6%), supplemented by a NaHCO3 alkalinity-salinity buffering strategy, to enable the reactor to maintain a volumetric loading rate ≥3.5 kg COD / m³ even under salinity fluctuations of 0-6%. 3 ·d, achieving an anaerobic stable treatment effect for high-salt photoresist wastewater that was previously unforeseen in this field.

[0059] (6) A / O biochemical and graded enhanced deep treatment:

[0060] A / O Biochemistry:

[0061] Anoxic zone: DO≤0.5mg / L, hydraulic retention time about 8h, sludge return ratio about 100%, denitrifying bacteria reduce nitrate nitrogen to nitrogen gas;

[0062] Aerobic section: DO controlled at 2-4 mg / L, hydraulic retention time approximately 12 h, MLSS approximately 3600 mg / L, aeration intensity 2-3 m³ / h. 3 / m 2 •h, to achieve further removal of residual organic matter and ammonia nitrogen;

[0063] During the start-up period, use 0.2 kg COD / m³ 3 • Increase the influent load gradually by approximately 0.1 kg COD / m³ every 3 days. 3 ·d, until approximately 1.0 kg COD / m 3 ·d.

[0064] Secondary sinking and adaptive depth processing:

[0065] The A / O effluent enters the secondary sedimentation tank, and after sedimentation and separation, the supernatant enters the adaptive sedimentation enhancement system; the COD and SS of the secondary sedimentation effluent are monitored online, and the mode is switched according to the water quality classification.

[0066] When COD≤50mg / L and SS≤5mg / L, only coagulation and flocculation are performed: add PAC (FeCl3, dosage 50-100mg / L) and anionic PAM (1-3mg / L), control pH 6-8, stir rapidly at 100-150r / min×5min, and stir slowly at 30-50r / min×15min.

[0067] When 50 < COD ≤ 80 mg / L or 5 < SS ≤ 10 mg / L, coagulation and flocculation are combined with the addition of 30-50 mg / L activated carbon to enhance adsorption.

[0068] When COD > 80 mg / L or SS > 10 mg / L, coagulation and flocculation are performed, and 50-100 mg / L of activated carbon is added to extend the adsorption reaction time by 15 min.

[0069] The adsorbent material can be periodically thermally regenerated (regeneration temperature approximately 800-900℃, regeneration cycle 3-6 months, adsorption capacity recovery rate ≥85% after regeneration). Waste adsorbent is disposed of as hazardous waste. The effluent from the advanced treatment enters the final discharge pool. If online monitoring fails (water quality exceeds standards), it is returned to the composite wastewater storage tank for retreatment via a return pump.

[0070] The A / O biological treatment section achieves stable removal of organic matter and nitrogen through precise DO control and residence time design, combined with front-end anaerobic hydrolysis / nutrient regulation; the advanced treatment unit switches between coagulation / adsorption modes according to the grade of effluent quality, ensuring stable compliance with standards while achieving efficient utilization and regeneration of adsorption materials.

[0071] (7) Treatment of sludge and other by-products

[0072] Sludge separation and treatment:

[0073] Biological sludge from the secondary sedimentation tank is discharged into the biological sludge tank, and chemical sludge from the neutralization, degassing, and sedimentation tank is discharged into the chemical sludge tank for separate storage. The biological sludge is dewatered by a screw press (dosage 0.1-0.3 kg / t, reagent is cationic PAM), and the chemical sludge is dewatered by a plate and frame filter press (dosage 0.5-1.0 kg / t, reagent is cationic PAM + lime). The moisture content of the dewatered sludge is ≤80%, and then it is dried at low temperature to reduce the moisture content to ≤35%. The dried sludge is identified by hazardous characteristics (such as leaching toxicity, acute toxicity) and then transferred for incineration or solidification and landfill according to the hazardous waste regulations.

[0074] Concentrated salt treatment:

[0075] The concentrated salt (salt content ≥60%) produced by MVR evaporation is collected in a concentrated salt collection tank; after hazardous characteristic identification, if it meets the recycling standards, sodium chloride is recovered through a salt separation and crystallization device; otherwise, it is solidified with cement and disposed of as hazardous waste.

[0076] Biogas treatment:

[0077] Daily biogas production after desulfurization and dehydration ≥ 500 m³ 3 A gas-fired power generation system can be configured when the daily gas volume is <500m³ / d; 3 When the emissions are at / d, they are disposed of by flare incineration; the exhaust gas from the incineration must meet the requirements of the Integrated Emission Standard of Air Pollutants GB16297-1996.

[0078] By separating and treating sludge and using low-temperature drying, the dewatering efficiency and volume reduction are improved; concentrated salt and biogas are designed with a dual-pathway approach of resource utilization and hazardous waste management to ensure environmental compliance throughout the process and reduce the risk of secondary pollution.

[0079] (8) Full-process PLC collaborative control system

[0080] Each unit's monitoring instrument collects key data in real time, updating at a frequency no higher than 1 minute, and transmits the data to the PLC controller. The PLC, according to preset logic, links and executes the following mechanisms: switching of the different types of flow valves; adjustment of Fenton reagent and nutrient dosage; regulation of the orifice diameter and pressure of the hydrolysis acidification water distributor; and operation parameters of the EGSB and A / O tanks, etc. The response time is generally no more than 10 minutes.

[0081] Emergency response to malfunctions and abnormal operating conditions: The monitor will automatically switch to manual mode and alarm when it malfunctions; the liquid level in the chemical storage tank will automatically trigger a shutdown or flow restriction alarm when it is below 10%; the EGSB biogas pressure will automatically depressurize and cut off the water supply when it exceeds the preset upper limit (e.g., >0.15MPa).

[0082] By integrating multiple unit parameters such as water separation, advanced oxidation, nutrient addition, hydrolysis and water distribution, anaerobic / aerobic operation, and deep treatment into a coordinated automatic control system, the system achieves full-process linkage and emergency protection, thereby improving the system's operational stability and ease of operation.

[0083] Performance testing

[0084] (1) Verify the steady-state operation of the system under normal fluctuations, focusing on verifying the optimization effect of MVR condensate reuse and IV zone (green zone) dilution on the EGSB influent environment. A continuous flow experiment was conducted using comprehensive wastewater from a semiconductor photoresist production workshop. The experiment ran for 2 weeks. Ordinary anaerobic granular sludge was selected as the inoculated sludge. Before the formal experiment, a 60-day salt gradient acclimatization was carried out. The specific steps were as follows: the sludge was added to the EGSB reactor (temperature 35±1℃, pH 6.8-7.5). From day 1 to 15, the salinity was gradually increased from 0.5% to 1.5%; from day 16 to 30, it was increased to 3.0% and the COD removal rate was stabilized; from day 31 to 45, an external osmotic pressure regulator (such as betaine) was added and the salinity was increased to 4.5%; from day 46 to 60, the salinity was increased to the final target of 6.0% and the system was stabilized until gas production was stable. The EGSB was controlled at 35±1℃.

[0085] Water quality testing during the experiment was conducted using standard methods. The key indicator, toxicity inhibition rate, was determined using the "Determination of Acute Toxicity of Water - Luminescent Bacteria Method" (GB / T 15441-1995). *Bacillus luminescenceis* was used as the test species, and the percentage of luminescence intensity inhibition was calculated after contact at 20±1℃ for 15 minutes. Average water quality data for the influent and effluent of each unit are shown in Table 1.

[0086] Table 1 Average water quality data of influent and effluent for each unit

[0087]

[0088] As shown in Table 1, the raw water has a complex composition, containing photoresist solvents and exhibiting extremely poor biodegradability. After evaporation, the organic matter is mainly composed of small molecules with a high B / C ratio. As high-quality dilution water, strong oxidation breaks bonds, reducing toxicity and initially increasing the B / C ratio to above 0.25. Through dilution in Zone IV / condensate, the salinity decreased from 7.5% to 1.8% (within the suitable range). After adaptive Fenton dilution, toxicity was significantly reduced, and the B / C ratio further increased to above 0.35, making it suitable for anaerobic digestion. The COD removal rate of the EGSB effluent is >83%, and the operation is stable. After further removal of most organic matter in the biological treatment section, the effluent COD is <100mg / L, fully meeting the standards. Therefore, Experimental Group 1, by intercepting the ultra-high concentration wastewater at the source in the red zone and evaporating and desalinizing the high-salinity wastewater in the orange zone, combined with peak shaving and valley filling and quality-differentiated allocation, ensured that even with a raw water COD as high as 45,000, the water quality entering the anaerobic system remained stable at around 7,000 COD, with suitable salinity, thus ensuring that the effluent met the standards.

[0089] Table 1 data strongly demonstrates the shielding and conditioning effect of the present invention's adaptive diversion strategy on the biological system. Although the raw water exhibits extreme volatility, after intelligent diversion and allocation at the front end, the water quality entering the core EGSB reactor is successfully locked within the optimal metabolic range for microorganisms (salinity 1.8%, COD approximately 6800 mg / L). More importantly, the toxicity inhibition rate of the EGSB influent is controlled below 10%, far lower than the 40% of the raw water. This indicates that the present invention is not a simple unit series connection, but rather, through pre-emptive logical diversion, it tames the drastically fluctuating industrial wastewater into stable wastewater before it enters the biological treatment stage, thereby ensuring a high COD removal rate.

[0090] (2) Comparison test of impact load resistance

[0091] The experimental group used the red / orange / yellow / green four-zone intelligent diversion method of this invention. The control group had no diversion; all wastewater was mixed and entered the equalization tank before entering the biological treatment system. Impact conditions: high-concentration wastewater (COD 120000 mg / L, salinity 6%, falling within the critical value of the "red / yellow zone"). Average influent and effluent water quality data for each unit are shown in Table 2.

[0092] Table 2 Average water quality data of influent and effluent for each unit

[0093]

[0094] Table 2 shows that both the experimental and control groups functioned normally after Fenton treatment before entering the EGSB system. After 6-7 days of operation, the high-concentration wastewater in the experimental group was automatically switched to incineration / MVR, resulting in almost no fluctuation in the EGSB influent; the high-load direct impact on the anaerobic sludge in the control group. After 8-10 days of operation, the experimental group's influent was identified as yellow, and strong Fenton treatment with dilution was initiated. Even with a high influent load (nearly 20,000 mg / L), the EGSB maintained approximately 85% removal rate; the sludge in the control group turned black and floated to the surface, showing severe acidification. After 10-14 days of operation, the experimental group system quickly returned to steady state, while the control group system required 15-20 days to recover or needed re-inoculation. This invention, through logical diversion, endows the biological system with shock resistance unmatched by traditional processes.

[0095] Table 2 shows the comparative test results, revealing the stability of the present invention under extreme operating conditions. The control group only took 2 days from normal operation to system failure, confirming the problems of existing single-mixing processes when faced with photoresist waste leakage or high-concentration cleaning water discharge. In contrast, even under the extreme impact of a 10-fold increase in influent load, the various indicators of the biochemical section of the present invention remained stable.

[0096] (3) Experiment on the effect of adaptive Fenton oxidation pretreatment

[0097] The experimental group used the adaptive Fenton oxidation pretreatment of this invention, while the control group used a fixed dosing method. A comparative experiment was conducted between the experimental and control groups, and the specific results are shown in Table 3.

[0098] Table 3. Effects of Adaptive Fenton Oxidation Pretreatment

[0099]

[0100] Table 3 shows that for low-concentration, highly toxic wastewater, the experimental group reduced the toxicity to a safe level, increasing the effluent B / C ratio from 0.1 to 0.32, thus preserving the subsequent microorganisms. The control group, however, had an effluent B / C ratio of only 0.15, indicating system poisoning. For conventional cleaning water, the experimental group saved on reagent costs, while the control group ineffectively added reagents, resulting in waste and increased sludge volume. The data in Table 3 demonstrates that the adaptive logic of this invention successfully identified latent toxicity risks and implemented excessive oxidation, effectively intercepting toxic substances sufficient to cause biochemical collapse, while the fixed-dose control group suffered system paralysis due to insufficient oxidation. Conversely, in low-load scenarios, this invention significantly reduced reagent consumption, avoiding reagent waste and increased costs for subsequent iron sludge treatment.

[0101] (4) EGSB and A / O process synergy verification test

[0102] To verify the necessity of the "anaerobic + aerobic" multi-stage synergy of this invention, three sets of comparative experiments were set up. The influent COD was uniformly controlled at 5000 mg / L and the salinity was 1.5%. The experimental results are shown in Table 4. The specific experiments are as follows:

[0103] Control group A (A / O only): No anaerobic section, wastewater directly enters the A / O tank.

[0104] Control group B (EGSB only): No aerobic stage, wastewater is discharged only after being treated by EGSB.

[0105] Experimental group (EGSB+A / O of this invention): Complete process.

[0106] Table 4. Results of the synergistic effect verification test between EGSB and A / O processes

[0107]

[0108] As shown in Table 4, control group A experienced severe sludge bulking under high load and had extremely high energy consumption; while control group B had low energy consumption, the EGSB had limited removal capacity for low-concentration residual COD, and the effluent could not be directly discharged. In this invention, the experimental group utilized EGSB to handle over 80% of the COD load, significantly reducing the energy consumption of the subsequent A / O stage, while simultaneously ensuring the final effluent quality through the A / O stage, demonstrating the significant advantages of multi-stage synergy.

[0109] (5) Salinity tolerance gradient pressure test

[0110] To verify the advantages of the "nutrient regulation + salt-tolerant sludge" system of this invention, the influent salinity was gradually increased (salinity settings of 1.5%, 3%, 4%, and 5%). The COD removal rate changes of conventional activated sludge (existing technology) and the system of this invention were compared. The experimental results are shown in Table 5. The specific experiments are as follows:

[0111] Control group: The reactor was supplemented with ordinary activated sludge;

[0112] Experimental group: using nutrient regulation, the reactor was added with salt-tolerant sludge obtained after 60 days of salt gradient acclimatization in experiment (1).

[0113] Table 5 Results of Salinity Tolerance Gradient Pressure Test

[0114]

[0115] Table 5 shows that when the influent salinity is in the low-salt range of 1.5%, the treatment effect of this invention is comparable to that of existing technologies. However, as the salinity gradient increases, the difference between the two technologies widens exponentially: at a salinity of 3.0%, existing ordinary sludge cannot withstand osmotic pressure shocks, and cell dehydration leads to a sharp drop in removal rate to below 50%; while this invention, thanks to its adaptive nutrient regulation mechanism, maintains a stable COD removal rate of over 80%. When the salinity increases to the extreme condition of 5.0%, existing technologies completely fail (system collapse), while the dedicated salt-tolerant sludge system of this technology can still maintain a COD removal rate of over 60%. Experimental data fully demonstrate that the "nutrient regulation + salt-tolerant sludge" system of this invention significantly improves the stability and shock resistance of the photoresist wastewater treatment system under salinity fluctuations and high-salt environments compared to existing technologies.

[0116] Therefore, this invention employs multi-threshold, fractional flow control combined with adaptive adjustment of all process parameters, enabling it to handle photoresist wastewater with varying salt content (4%-40%) and COD (tens to hundreds of thousands of mg / L), thus solving the problem of insufficient adaptability in existing processes. Through targeted pretreatment, precise nutrient regulation, and efficient biochemical synergy, the B / C ratio during hydrolysis and acidification is increased to over 0.35, and the volumetric loading rate of the EGSB anaerobic reactor is stabilized at 3.5 kg COD / m³. 3• With a capacity of ≥99.9% for the entire process, the overall COD removal rate is ≥99.9%. Dynamic parameter adjustment avoids excessive addition of oxidants, nutrients, and adsorbents. Nutrient regulation reduces nitrogen and phosphorus waste. The adsorbent material is recyclable, and the overall operating cost can be reduced by more than 30% compared to traditional fixed processes. The whole process is coordinated and controlled, and the staged deep treatment ensures that the effluent COD is ≤40mg / L, SS is ≤5mg / L, ammonia nitrogen is ≤8mg / L, and total phosphorus is ≤0.5mg / L, with a compliance rate of ≥99%, unaffected by changes in wastewater type. Sludge is treated separately and dried to reduce volume. Concentrated salt is graded for resource utilization / hazardous waste management. Biogas is burned / generated after standard treatment. The automation level is high and the operation is simple: the whole process is automatically controlled by PLC and monitored online, with less manual intervention, suitable for large-scale industrial applications, reducing the difficulty of operation and labor costs.

[0117] The foregoing has shown and described the basic principles, main features, and advantages of this invention. Those skilled in the art should understand that the above experimental group does not limit this invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this invention.

Claims

1. A process for treating photoresist wastewater characterized by its self-adaptive, multi-segment synergistic enhancement, wherein... Includes the following steps: S1. Separate and adaptive diversion of photoresist wastewater: online monitoring of photoresist wastewater to obtain real-time data on salt content and chemical oxygen demand (COD). Wastewater is diverted to different pretreatment paths based on salinity and COD data. These pretreatment paths include resource recovery treatment, evaporation desalination treatment, enhanced pretreatment, and direct biological discharge treatment. S2, Fenton oxidation pretreatment: Fenton oxidation treatment is performed on the wastewater diverted to the enhanced pretreatment path, and the dosing mode is dynamically adjusted according to the influent COD concentration and / or biotoxicity index; S3, Biochemical degradation treatment: The wastewater that has undergone Fenton oxidation pretreatment is mixed with the wastewater that has undergone homogenization and conditioning treatment in the direct biological discharge treatment path, and the mixed wastewater is subjected to hydrolysis acidification treatment, anaerobic biological treatment and A / O aerobic biological treatment in sequence; S4. Deep Enhanced Treatment: Monitor the effluent from the A / O aerobic biological treatment, and automatically switch between coagulation mode and coagulation adsorption enhancement mode based on the real-time effluent water quality, and adjust the dosage of adsorption material.

2. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S1, the specific method for diverting wastewater based on salinity and COD data is as follows: (1) When the influent COD > 100,000 mg / L, the wastewater is diverted to the resource recovery treatment path for source interception and directed to the solvent recovery or incineration unit; (2) When the influent COD ≤ 100,000 mg / L and salinity ≥ 8%, the wastewater is diverted to the evaporation desalination treatment path for pre-oxidation and MVR forced circulation evaporation treatment; (3) When the influent COD ≤ 100,000 mg / L and salinity is 2%-8% or when the influent 5000 < COD ≤ 100,000 mg / L and salinity < 2%, the wastewater is diverted to the enhanced pretreatment path for Fenton oxidation pretreatment; (4) When the influent salinity < 2% and COD ≤ 5000 mg / L, the wastewater is diverted to the biochemical direct discharge treatment path and directed to the biochemical regulating tank for homogenization and dilution.

3. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S2, the dosing mode of Fenton oxidation pretreatment is switched according to the influent COD concentration and / or biotoxicity index. The specific methods are as follows: (1) High-intensity oxidation mode: when the influent toxicity inhibition rate is >50%, or when the influent toxicity inhibition rate is ≤50% and COD is >50000 mg / L, the mass addition ratio of H2O2 to COD is 0.4-0.47, and the reaction time is 45-60 min; (2) Standard enhancement mode: when the influent toxicity inhibition rate is ≤50% and 10000 mg / L < COD ≤ 50000 mg / L, the mass addition ratio of H2O2 to COD is 0.3-0.4; (3) Low-consumption conditioning mode: when the influent toxicity inhibition rate is ≤50% and COD ≤ 10000 mg / L, the mass addition ratio of H2O2 to COD is 0.2-0.

3.

4. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S2, according to H2O2 / Fe 2+ Ferrous iron was added to the system in a molar ratio of 3:1 to 4:1; the pH of the reaction system was 3.0 to 3.

5.

5. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S3, the wastewater entering the hydrolysis acidification tank is nutrient-controlled, specifically by adding nitrogen and phosphorus sources based on the COD, total nitrogen and total phosphorus concentrations of the mixed wastewater, according to the ratio of COD:total nitrogen:total phosphorus = 100:(3-5):(1-1.5), and adding a mixture of trace elements.

6. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S3, the hydrolysis acidification treatment adopts an upflow dynamic water distribution method. The orifice diameter of the water distributor is 5-8mm, the water distribution pressure is 0.1-0.3MPa, the upflow velocity in the pool is 0.5-1.2m / h, and the sludge concentration in the pool is 15-30g / L.

7. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S3, the anaerobic biological treatment uses an expanded granular sludge bed (EGSB) reactor, which is inoculated with salt-tolerant anaerobic granular sludge with an alkalinity of 2000-3000 mg / L.

8. The photoresist wastewater treatment process according to claim 1, characterized in that, In step S4, the adaptive deep enhancement treatment uses an activated carbon dosing device. When the monitored effluent COD > 50 mg / L or suspended solids > 5 mg / L, 30-150 mg / L of activated adsorbent material is added, and solid-liquid separation is carried out through an inclined tube sedimentation tank.

9. The photoresist wastewater treatment process according to claim 2, characterized in that, The condensate generated in the evaporation desalination process is equipped with an online secondary discrimination branch: when the COD of the condensate is greater than 5000 mg / L, the condensate is directed to the front end of the Fenton oxidation pretreatment for secondary treatment.

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