Emergency sewage treatment process for expressway service area

Abstract

The invention relates to the technical field of sewage treatment, in particular to an expressway service area sewage emergency treatment process which comprises the following steps: sewage is guided into a flocculation basin for flocculation treatment, the flocculation basin is used for preliminarily removing suspended solids, organic matters and colloidal pollutants in the sewage, and the sewage is discharged from the flocculation basin; the flocculation mode comprises chemical dosing flocculation or electrochemical flocculation; introducing the flocculated sewage into a membrane filtration tank for solid-liquid separation, wherein an ultrafiltration membrane assembly for filtering floc particles is arranged in the membrane filtration tank; the sewage subjected to membrane filtration is conveyed to an electrochemical oxidation pond, the electrochemical oxidation pond is provided with an anode plate and a cathode plate, and an electrolytic reaction is carried out by applying voltage. A'flocculation-membrane separation-electrochemical oxidation 'short-process system is constructed, suspended solids, ammonia nitrogen and refractory pollutants are quickly removed, the process is quick to start and stable in operation, effluent does not need to be disinfected, and the method is suitable for emergency scenes such as sudden standard exceeding and the like.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an emergency treatment process for wastewater in highway service areas. Background Technology

[0002] Highway service areas, as comprehensive facilities providing services such as dining, rest, car washing, and restrooms for passing drivers and passengers, continuously generate diverse and multi-source wastewater during their daily operations. This includes kitchen wastewater, black water from toilets, recycled water from car washes, and domestic sewage from staff dormitories. This wastewater has a high pollution load and complex composition. Especially during short periods such as holidays and highway congestion, wastewater discharge exhibits strong temporal variability and suddenness, with fluctuations in water quality and quantity far exceeding those of general municipal wastewater.

[0003] Currently, most wastewater treatment plants in service areas primarily use conventional biological treatment processes, such as contact oxidation and SBR systems. While these systems are effective at removing stable wastewater, they are virtually powerless in the face of emergencies such as sudden overload, equipment failure, cold weather, or biological system collapse. If the concentration of pollutants in the influent exceeds standards or the treatment capacity is insufficient in a short period, it often leads to severe deterioration of the effluent quality, or even direct discharge, which can easily cause river pollution, foul odors, and consequently trigger regulatory penalties and public opinion risks.

[0004] Traditional coagulation and flocculation processes, as an important component of physicochemical treatment, offer advantages such as ease of operation, rapid reaction speed, and strong adaptability, making them widely used in emergency response. However, conventional coagulation methods still have many limitations: such as limited removal efficiency for different pollutants, floc settling performance greatly affected by temperature and chemical dosing, large sludge production, and difficulty in consistently meeting effluent standards. Especially in the absence of advanced treatment units (such as membrane filtration and electrochemical oxidation), it is often difficult to meet the current "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants".

[0005] Therefore, there is an urgent need to develop a short-process emergency treatment technology based on conventional coagulation and flocculation, combined with high-efficiency ultrafiltration membrane separation and electrochemical oxidation technology. This technology utilizes traditional coagulation to achieve preliminary removal of pollutants such as suspended solids, organic matter, and colloids, while membrane separation enhances solid-liquid separation. Furthermore, electrochemical oxidation further removes recalcitrant components such as ammonia nitrogen and bacteria, achieving efficient, stable, and rapid discharge that meets standards. This combined process offers advantages such as rapid start-up, modularity, small footprint, and controllable operation, making it particularly suitable for emergency water treatment needs in distributed scenarios such as highway service areas. Summary of the Invention

[0006] To address the aforementioned shortcomings in the existing technology, the objective of this invention is achieved through the following technical solution: This invention discloses an emergency treatment process for sewage treatment plants in highway service areas, comprising the following steps: 1) The wastewater is introduced into a flocculation tank for flocculation treatment. The flocculation tank is used to initially remove suspended solids, organic matter and colloidal pollutants in the wastewater. The flocculation method includes chemical dosing flocculation or electrochemical flocculation. 2) The wastewater after flocculation treatment is introduced into a membrane filtration tank for solid-liquid separation. The membrane filtration tank is equipped with an ultrafiltration membrane module for filtering floc particles. 3) The wastewater after membrane filtration is transported to an electrochemical oxidation tank, which is equipped with an anode plate and a cathode plate. An electrolytic reaction is carried out by applying voltage to generate active species with oxidizing ability in the oxidation tank, thereby further removing residual pollutants in the wastewater.

[0007] Preferably, In step (1), the flocculation method is chemical dosing flocculation.

[0008] The chemical dosing flocculation includes adding a coagulant and a flocculant to the flocculation tank. The coagulant is selected from polyaluminum chloride, aluminum sulfate, or ferrous sulfate, and the flocculant is selected from polyacrylamide or chitosan.

[0009] The dosage of the coagulant is 50-150 mg / L, and the dosage of the flocculant is 0.5-2.0 mg / L.

[0010] The flocculation tank is also added with an adsorbent, which is selected from activated carbon, diatomaceous earth or bentonite.

[0011] The dosage of the adsorbent is 10-150 mg / L.

[0012] The flocculation tank is equipped with a dosing device for simultaneously adding coagulants, flocculants, and adsorbents to the wastewater in proportion.

[0013] The flocculation tank is equipped with an aeration device to provide gas-liquid mixing during the flocculation reaction process to enhance the mixing effect and promote floc formation.

[0014] The hydraulic retention time of the flocculation tank is 15-60 minutes.

[0015] In step (1), the flocculation method is electrochemical flocculation.

[0016] The electrochemical flocculation process involves setting up an anode plate and a cathode plate in a flocculation tank and applying a DC voltage to generate metal ions in situ as flocculants.

[0017] The anode plate is an aluminum plate or an iron plate, and the cathode plate is a stainless steel plate or a graphite plate.

[0018] The voltage between the anode and cathode is 2-36V, and the current density is 5-50mA / cm². 2 .

[0019] During the electrochemical flocculation process, a chemical flocculant is also added through a dosing device to enhance the flocculation effect. The flocculant is selected from polyacrylamide or chitosan.

[0020] The hydraulic retention time of the flocculation tank is 15-60 minutes.

[0021] In step (2), The pore size of the ultrafiltration membrane module is 0.02-0.2 micrometers.

[0022] The ultrafiltration membrane module is selected from ceramic membranes, flat sheet membranes, or hollow fiber membranes.

[0023] The membrane filtration tank is equipped with a suction pump to drive the membrane filtration process.

[0024] The membrane filtration tank is equipped with a circulation pump for cross-flow flushing of the ultrafiltration membrane to mitigate membrane fouling.

[0025] The membrane filtration tank is equipped with an aeration device to create turbulent airflow around the membrane module, thereby increasing the shear force on the membrane surface and reducing the risk of membrane fouling.

[0026] In step (3), The anode plate of the electrochemical oxidation cell is a titanium-based anode plate coated with metal oxides such as ruthenium and iridium, and the cathode plate is a stainless steel plate or a titanium plate.

[0027] The anode plate and cathode plate are configured as parallel plates, arranged at intervals, to form a uniform electric field and improve electrolysis efficiency.

[0028] Sodium chloride is added to the electrochemical oxidation cell as an auxiliary electrolyte to improve conductivity and promote the generation of active oxide species such as hypochlorite.

[0029] The dosage of sodium chloride is calculated based on adding 3-5 mg / L of sodium chloride for every 1 mg / L of ammonia nitrogen removed.

[0030] The hydraulic residence time of the electrochemical oxidation cell is 5-30 minutes. The voltage between the anode and cathode is 2-36V, and the current density is 5-50mA / cm². 2 .

[0031] The electrochemical oxidation tank is equipped with an aeration device to introduce air or oxygen into the tank to enhance the oxidation reaction efficiency and mass transfer rate.

[0032] A reflux channel is provided between the membrane filtration tank and the flocculation tank, through which part of the concentrated water in the membrane filtration tank flows back to the flocculation tank, realizing recycling.

[0033] This invention presents a short-process "flocculation-membrane separation-electrochemical oxidation" technology suitable for emergency treatment of wastewater from highway service areas. The flocculation unit removes suspended solids and colloidal particles, reducing membrane load; membrane filtration efficiently retains flocs, ensuring effluent clarity; electrochemical oxidation generates active species such as hypochlorite ions in situ at the anode, further removing ammonia nitrogen and recalcitrant pollutants. This process features rapid start-up, independence from biochemical reactions, and no need for effluent disinfection. It boasts advantages such as high treatment efficiency, high system integration, and strong operational controllability, making it suitable for emergency scenarios such as sudden wastewater exceedances. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a side view of the wastewater treatment process structure described in Example 1; Figure 2 This is a top view of the wastewater treatment device described in Example 1; Figure 3 Side view schematic diagram of the wastewater treatment process structure based on the electrochemical flocculation pathway described in Example 2; Figure 4 A top view of the wastewater treatment system described in Example 2. Detailed Implementation

[0036] The invention will be more readily understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the definitions in this specification shall prevail.

[0037] This invention discloses an emergency treatment process for sewage treatment plants in highway service areas, comprising the following steps: 1) Wastewater is introduced into a flocculation tank for flocculation treatment. The flocculation tank is used to initially remove suspended solids, organic matter, and colloidal pollutants from the wastewater. Flocculation methods include chemical flocculation or electrochemical flocculation. Through efficient flocculation, most pollutants are pre-removed, reducing the load on subsequent membrane filtration and electrolysis.

[0038] 2) The flocculated wastewater is introduced into a membrane filtration tank for solid-liquid separation. The membrane filtration tank is equipped with an ultrafiltration membrane module for filtering floc particles. This further removes residual flocs and fine suspended solids, ensuring effluent quality and protecting the stable operation of the subsequent electrochemical system.

[0039] 3) The membrane-filtered wastewater is transported to an electrochemical oxidation tank, which is equipped with an anode plate and a cathode plate. An electrolytic reaction is initiated by applying voltage to generate active species with oxidizing capabilities within the oxidation tank, thereby further removing residual pollutants from the wastewater. This strong oxidation reaction effectively removes recalcitrant pollutants, ensuring that the final effluent meets discharge standards.

[0040] In step (1), the flocculation method is chemical flocculation. This method rapidly forms flocs by adding chemical reagents, making it suitable for emergency treatment under sudden high load conditions.

[0041] The chemical dosing flocculation involves adding a coagulant and a flocculant to the flocculation tank. The coagulant is selected from polyaluminum chloride, aluminum sulfate, or ferrous sulfate, and the flocculant is selected from polyacrylamide or chitosan. This combined addition achieves a synergistic effect of bridging and neutralization, significantly improving flocculation efficiency.

[0042] The dosage of the coagulant is 50-150 mg / L, and the dosage of the flocculant is 0.5-2.0 mg / L. Controlling the dosage within the effective range ensures treatment effectiveness while avoiding resource waste and side effects.

[0043] The flocculation tank is also supplemented with an adsorbent selected from activated carbon, diatomaceous earth, or bentonite. This enhances the adsorption and fixation capacity for hydrophobic organic pollutants and trace heavy metals, addressing the shortcomings of traditional flocculation methods.

[0044] The dosage of the adsorbent is 10-150 mg / L. This can be flexibly adjusted according to the pollutant concentration to improve the adaptability and economy of the treatment.

[0045] The flocculation tank is equipped with a dosing device for simultaneously adding coagulants, flocculants, and adsorbents to the wastewater in proportion. This enables automated control and synchronized reaction, improving dosing accuracy and reaction efficiency.

[0046] The flocculation tank is equipped with an aeration device to provide gas-liquid mixing during the flocculation reaction, thereby enhancing the mixing effect and promoting floc formation. Gas disturbance improves mass transfer and contact efficiency, accelerating floc growth and sedimentation.

[0047] The hydraulic retention time in the flocculation tank is 15-60 minutes. This provides sufficient reaction time to complete particle aggregation, structural stabilization, and initial sedimentation, creating favorable conditions for membrane filtration pretreatment.

[0048] In step (1), the flocculation method is electrochemical flocculation. Flocculants can be generated through electrode dissolution without the need for external coagulants, making it suitable for scenarios where reagents are limited or a rapid response is required.

[0049] The electrochemical flocculation process involves setting up an anode and cathode plate in a flocculation tank and applying a DC voltage to generate metal ions in situ as a flocculant. These metal ions rapidly hydrolyze in water to form hydroxides, creating a network structure for the removal of colloids and organic matter.

[0050] The anode plate is made of aluminum or iron, and the cathode plate is made of stainless steel or graphite. Choosing appropriate electrode materials determines the type and efficiency of the reaction products, ensuring a stable release of flocculated ions.

[0051] The voltage between the anode and cathode is 2-20V, and the current density is 5-50mA / cm². 2 By adjusting the voltage and current density, the release rate of metal ions and the intensity of electrochemical reactions can be controlled, enabling refined operation management.

[0052] During the electrochemical flocculation process, a chemical flocculant, such as polyacrylamide or chitosan, is added via a dosing device to enhance the flocculation effect. This combined approach enhances the electrochemical flocculation effect, improves the removal rate, and is particularly suitable for waters with fluctuating loads or complex water qualities.

[0053] The hydraulic retention time in the flocculation tank is 15-60 minutes. This ensures that the electrochemical reaction and floc formation are fully completed, laying the foundation for subsequent membrane separation.

[0054] In step (2), the pore size of the ultrafiltration membrane module is 0.02-0.2 micrometers. The pore size design can effectively retain flocs and bacteria while ensuring a moderate water flux, thus balancing treatment efficiency and stability.

[0055] The ultrafiltration membrane module is selected from ceramic membranes, flat sheet membranes, or hollow fiber membranes. Various membrane types can be flexibly selected based on site and water quality conditions to meet diverse emergency needs.

[0056] The membrane filtration tank is equipped with a suction pump to drive the membrane filtration process. It provides a stable negative pressure or transmembrane pressure difference to ensure the continuity and controllability of system operation.

[0057] The membrane filtration tank is equipped with a circulation pump for cross-flow flushing of the ultrafiltration membrane to mitigate membrane fouling. The cross-flow creates shear force disturbance, effectively preventing contaminant deposition on the membrane surface and pore blockage.

[0058] The membrane filtration tank is equipped with an aeration device to create turbulent airflow around the membrane module, thereby increasing the shear force on the membrane surface and reducing the risk of membrane fouling. This air turbulence further increases the interfacial velocity, improving membrane flux and cleaning cycle intervals.

[0059] In step (3), the anode plate of the electrochemical oxidation cell is a titanium-based metal oxide-coated anode plate supported on ruthenium or iridium, and the cathode plate is a stainless steel plate or a titanium plate. Ruthenium or iridium-based anodes have excellent electrocatalytic performance and corrosion resistance, ensuring the continuous and efficient generation of active species.

[0060] The anode and cathode plates are configured as parallel plates, arranged at intervals to create a uniform electric field and improve electrolysis efficiency. Optimizing the electric field distribution enhances oxidation efficiency and avoids problems such as short circuits and excessively strong localized electrolysis.

[0061] Sodium chloride is added to the electrochemical oxidation cell as an auxiliary electrolyte to improve conductivity and promote the formation of active oxides such as hypochlorite. This enhances the electrolytic current conduction capacity and guides the formation of effective products (such as HOCl), thereby improving the pollutant degradation efficiency.

[0062] The sodium chloride dosage is calculated based on 3-5 mg / L sodium chloride per 1 mg / L of ammonia nitrogen removed. This ensures an effective dose to generate sufficient oxide species while avoiding resource waste and corrosion risks from excessive dosage.

[0063] The hydraulic retention time in the electrochemical oxidation tank is 5-30 minutes. This ensures that the oxidation reaction is sufficiently completed, guaranteeing the effective degradation of target substances such as ammonia nitrogen and organic pollutants.

[0064] The electrochemical oxidation tank is equipped with an aeration device to introduce air or oxygen into the tank to enhance the oxidation reaction efficiency and mass transfer rate. This increases the dissolved oxygen concentration, accelerates the pollutant oxidation process, and strengthens the synergistic oxidation effect.

[0065] A reflux channel is provided between the membrane filtration tank and the flocculation tank. Part of the concentrated water from the membrane filtration tank flows back to the flocculation tank through this reflux channel, achieving recycling. This reduces the burden of concentrated water treatment, recovers residual pollutants, and improves the overall utilization rate and sustainability of the system.

[0066] Example 1: like Figure 1 As shown in Example 1, the emergency wastewater treatment process structure includes a coagulation and flocculation tank, an ultrafiltration membrane filtration tank, and an electrochemical oxidation tank arranged in series. Wastewater enters the coagulation and flocculation tank through the inlet, where coagulant, flocculant, and auxiliary adsorbent are simultaneously added at the dosing port. Gas-liquid mixing is achieved through a bottom aeration device to form flocs. The flocculated wastewater flows by gravity into the ultrafiltration membrane filtration tank, which is equipped with an ultrafiltration membrane module and a suction pump at the end to maintain the filtration pressure differential. A circulation pump and aeration system are also used to mitigate membrane fouling. The membrane effluent flows through a pipeline into the electrochemical oxidation tank, which contains anode and cathode plates, an aeration device at the bottom, and an outlet at the top. Wastewater treatment is completed after the electrolytic oxidation reaction.

[0067] like Figure 2The diagram shown is a top-view structural diagram of the above-mentioned treatment system, which more clearly illustrates the arrangement of the various unit devices. The coagulation and flocculation tank has multiple inlets, and the ultrafiltration membrane filtration tank is equipped with two sets of membrane modules arranged in parallel. The suction pump is located at the end of the membrane tank and connected to the electrochemical oxidation tank. The membrane filtration tank is also equipped with a reflux zone to return a portion of the concentrated water to the flocculation tank, thereby enhancing the system's circulation stability and improving treatment efficiency.

[0068] This embodiment provides a short-process emergency treatment technology suitable for sewage treatment plants in highway service areas, specifically addressing scenarios requiring compliant sewage discharge due to sudden pollutant exceedances, biochemical system shutdowns, or temporary capacity expansion needs. The treatment process consists of three core units sequentially: a chemical dosing flocculation unit, a membrane filtration separation unit, and an electrochemical oxidation deep treatment unit. Together, they form a highly efficient synergistic treatment system of "chemical flocculation – membrane separation – electrochemical oxidation," characterized by a short process, rapid reaction, stable treatment, and simple operation.

[0069] I. Chemical Dosing Flocculation Unit Wastewater first enters the flocculation tank through the inlet pipe. The tank is equipped with an automatic dosing system and an aeration and mixing system to achieve the initial enrichment of pollutants in the raw water and the formation of flocs. The dosage of chemicals is automatically controlled according to the influent flow rate, as follows: Coagulant: Polyaluminum chloride (PAC), dosage 100 mg / L, used to neutralize the surface charge of colloidal particles and break the stable structure; Flocculant: Cationic polyacrylamide (PAM), dosage 1.0 mg / L, used to bridge micro-flocs and promote their formation of large particle structure; Auxiliary adsorbent: powdered activated carbon, dosage 100 mg / L, used to adsorb dissolved organic matter and some heavy metal ions in water.

[0070] After the chemical is added, the bottom aeration device continuously blows air into the flocculation tank, creating a gas-liquid mixing state, which not only enhances the efficiency of the coagulation reaction but also promotes the rapid growth and floating of flocs. The flocculation reaction time is set to 30 minutes to ensure the formation of flocs with a dense structure, good settling properties, and easy subsequent membrane separation.

[0071] II. Membrane Filtration Separation Unit After flocculation, the wastewater flows by gravity into a membrane filtration tank. This tank contains a ceramic ultrafiltration membrane module with a pore size of 0.05 microns, used for the efficient removal of suspended particles and large organic molecules. The membrane module has a hollow fiber structure and is made of high-strength alumina, exhibiting excellent fouling resistance and chemical stability. The membrane flux is designed to be 80 L / m³. 2 ·h.

[0072] The key operating conditions are as follows: Drive method: A suction pump is installed at the end of the membrane tank to provide constant negative pressure to drive membrane filtration; Membrane surface cleaning: Equipped with a circulation pump with a flow rate 4 times that of the feed flow rate, it is used to laterally flush the membrane surface to slow down the deposition of contaminants; Gas disturbance: The bottom of the membrane module is equipped with a microporous aeration device that continuously blows in air to form a disturbed flow field, which enhances the shear force on the membrane surface and delays membrane fouling; Concentrate return: The membrane concentrate is returned to the flocculation tank through a dedicated return pipeline, effectively recovering residual reagents and pollutants, and improving the overall resource utilization rate and hydraulic stability of the system.

[0073] III. Electrochemical Oxidation Deep Processing Unit The effluent from the membrane enters the electrochemical oxidation tank for deep purification. This unit is equipped with a titanium-based IrO2 / RuO2 composite oxide anode plate (DSA anode) and a stainless steel cathode plate, arranged in parallel to form a stable and uniform electric field. Operating conditions are as follows: Applied voltage: constant 10V; Current density: 20 mA / cm 2 ; Electrolysis time: 30 minutes; Auxiliary electrolyte: Sodium chloride is added simultaneously, controlled at a ratio of 3.5 mg / L sodium chloride per 1 mg / L ammonia nitrogen, to enhance the conductivity of the system; Aeration system: Air is continuously blown into the bottom of the reaction tank to accelerate the mass transfer rate and enhance the activity of the reaction interface.

[0074] During electrolysis, the anode surface generates ·OH and ClO through direct oxidation and indirect formation. - The strong oxidant can completely degrade residual organic matter, ammonia nitrogen and other micro-pollutants behind the membrane, while also having a certain bactericidal and disinfection function, making the effluent colorless, odorless and transparent, without the need for a special disinfection facility.

[0075] IV. Evaluation of Process Performance In a laboratory simulation of wastewater treatment, actual mixed domestic wastewater from a highway service area (SS=200mg / L, COD=600mg / L, NH3-N=80mg / L) was selected as the treatment target. The water quality after treatment is as follows:

[0076] This short-process "chemical flocculation-membrane separation-electrochemical oxidation" technology can achieve efficient treatment without relying on traditional biochemical systems, and has the following outstanding advantages: rapid start-up, no inoculation or acclimatization required; compact process, small footprint, easy to install on vehicles or in modular containers; stable effluent, effectively responding to water quality fluctuations and sudden changes in pollutant concentrations; highly versatile equipment, with emergency modules that can be flexibly added next to existing wastewater treatment plants; simple operation and management, high degree of automation, and flexible adjustment of reagent and power consumption according to actual conditions.

[0077] In summary, this technology is particularly suitable for scenarios such as highway service areas. When the original sewage treatment system cannot operate stably due to failure, overload, or the need for temporary expansion, it can be quickly put into use as an emergency discharge treatment solution to achieve efficient reduction of pollutants and ensure that the effluent quality meets the standards.

[0078] Example 2: like Figure 3 As shown, the wastewater treatment process structure described in Example 2 consists of an electrochemical flocculation tank, a membrane filtration tank, and an electrochemical oxidation tank connected in series. Wastewater first enters the electrochemical flocculation tank through the inlet pipe, where a uniform electric field is formed between the anode aluminum plate and the cathode stainless steel plate. The anode aluminum plate continuously dissolves under constant voltage electrolysis conditions, releasing Al. 3+ Aluminum hydroxide agglomerates are formed in the water; simultaneously, cationic PAM is added to enhance the floc structure and improve sedimentation and retention efficiency. An aeration device is installed at the bottom of the flocculation tank to enhance mixing and flocculation through gas-liquid disturbance.

[0079] like Figure 4 The diagram shown is a top-view structural schematic of the wastewater treatment system in this embodiment, which more clearly illustrates the spatial arrangement and flow path between the various treatment units. The electrochemical flocculation tank and the membrane filtration tank are connected by gravity through pipelines. The membrane tank is equipped with columnar ceramic membrane modules and a horizontal circulation pump and a bottom microporous aeration system to enhance membrane shear force and delay fouling. The concentrate from the membrane tank is returned to the electrochemical flocculation tank through a return pipeline, forming a closed-loop resource system; the effluent from the membrane further enters the electrochemical oxidation tank, where deep removal of pollutants is achieved under a strong oxidizing environment.

[0080] This embodiment provides an emergency treatment process for wastewater treatment plants in highway service areas based on an electrochemical flocculation pathway. It is suitable for rapid emergency treatment when biochemical systems fail or when wastewater contains high concentrations of emulsified oil, organic colloids, and other recalcitrant pollutants.

[0081] I. Electrochemical Flocculation Unit The raw wastewater is introduced into an electrochemical flocculation tank, which is equipped with aluminum alloy anode plates and stainless steel cathode plates, each measuring 300mm × 200mm with a plate spacing of 10mm. The tank is controlled by a constant voltage DC power supply.

[0082] Anode material: Industrial pure aluminum plate (purity ≥ 99.5%) Cathode material: 304 stainless steel plate Voltage control: Apply DC voltage 10V Current density: approximately 30 mA / cm² 2 Hydraulic residence time: 30 minutes pH control: The raw water pH is approximately 6.8, requiring no additional adjustment. Assisted drug administration: Simultaneous administration of cationic polyacrylamide (PAM) at a dosage of 1.0 mg / L. During this process, the anode aluminum plate continuously dissolves, generating Al. 3+ The PAM is hydrolyzed into Al(OH)3 colloidal particles, which have strong adsorption capacity and can efficiently remove impurities such as emulsified oil, organic colloids, and suspended solids (SS) from the water, forming large-particle, loosely structured flocs that are easy to retain in subsequent processes. The aeration device provides a stable airflow, improves coagulation efficiency, and enhances the binding degree between PAM and colloids.

[0083] II. Membrane Filtration Unit After electrochemical flocculation, the water flows into the membrane filtration tank, which is equipped with a set of ceramic membrane modules with a pore size of 0.05μm. The membrane material is alumina, which has the characteristics of being resistant to fouling and rewashable, and is suitable for high load and changing water quality environments.

[0084] Membrane module type: Columnar ceramic membrane (single section area 0.5m²) 2 ) Operating pressure: approximately 0.1 MPa Operating mode: Negative pressure suction + cross-flow filtration Suction pump flow rate: 1.0 m³ / h 3 / h Circulation pump flow rate: 3.0 m³ / h 3 / h Aeration and mixing: A microporous aeration disc is installed at the bottom, with an air flow rate of 10L / min. The membrane filtration tank is designed with an open design, and an aerator is installed below the membrane module to create gas-liquid turbulence. The circulating pump generates a transverse shear flow, which can effectively reduce membrane fouling and extend its service life. The membrane effluent is directed to the downstream oxidation tank, while the membrane concentrate is returned to the flocculation tank to improve floc stability and prevent pollutant accumulation.

[0085] III. Electrochemical Oxidation Unit The effluent from the membrane enters the electrochemical oxidation tank, where anode and cathode plates (10mm apart) are arranged in parallel to form a stable electric field for deep oxidation treatment.

[0086] Anode material: Titanium-based metal oxide anode plate (DSA) supported on IrO2 and RuO2. Cathode material: Titanium plate Operating voltage: constant 24V Current density: 25 mA / cm 2 Hydraulic residence time: 20 minutes Auxiliary electrolyte: Add 4 mg / L sodium chloride at a concentration of 1 mg / L ammonia nitrogen. Aeration system: air flow rate 10L / min, enhancing oxidation and electroflotation effects. At the anode surface, water molecules and chloride ions undergo an oxidation reaction to produce •OH and ClO. - The strong oxidant effectively decomposes residual COD, organic amines, ammonia nitrogen, and other recalcitrant substances, enhancing the treatment depth. Gas blowing simultaneously strengthens mass transfer and aids in cleaning the electrode surface via electro-floating.

[0087] IV. Evaluation of Treatment Results Using wastewater from a highway service area (COD: 280 mg / L, SS: 180 mg / L, NH3-N: 25 mg / L) as the treatment target, the effluent quality after adopting the process of this embodiment is as follows:

[0088] After electrochemical oxidation, the effluent has no obvious color or odor, is clear and transparent, and meets the Class I discharge limit of the "Integrated Wastewater Discharge Standard", enabling rapid emergency discharge to meet the standards.

[0089] Example 3: The present invention further provides the following technical solution: an emergency treatment process for a sewage treatment plant in a highway service area, comprising the following steps: 1) Wastewater is introduced into a mixed oxidation reactor for electrocatalytic oxidation treatment. The reactor is equipped with titanium-coated anode plates and stainless steel cathode plates, which are arranged in parallel with a spacing of 10 mm. A constant DC voltage of 12 V and a current density of 25 mA / cm² are applied. 2 To carry out an electrolytic reaction; 2) During the electrocatalytic oxidation process, an inorganic salt auxiliary electrolyte, namely sodium chloride, is added to the reaction tank simultaneously. The amount added is 4 mg / L for every 1 mg / L of ammonia nitrogen removed. At the same time, an aeration system is set up to introduce air to improve the oxygen mass transfer efficiency and oxidation reaction rate in the reaction tank. 3) Potassium persulfate is further added as an exogenous oxidant during the electrocatalytic oxidation process, with the concentration controlled at 20 mg / L; 4) The water after mixed oxidation treatment is introduced into the sedimentation tank, and solid-liquid separation is achieved by gravity sedimentation. The clarified liquid is discharged through the upper outlet.

[0090] Specifically, this embodiment provides an emergency treatment process for wastewater treatment plants in highway service areas based on an "electrocatalytic oxidation + advanced oxidation composite pathway," which is particularly suitable for sudden wastewater scenarios with complex water composition and difficulties in treatment by conventional means.

[0091] In actual testing, domestic sewage from a highway service area next to a heavy-duty logistics transfer station was selected. This area experiences high daily traffic volume and contains a large amount of kitchen wastewater, flushing wastewater, and a very small amount of medical transport and disinfection wastewater. Overall, it exhibits high organic load, poor biodegradability, and trace amounts of recalcitrant pollutants. Typical influent water quality is as follows: COD 820 mg / L, SS 250 mg / L, NH3-N 56 mg / L, showing severe oil emulsification, high color, and excessive foaming.

[0092] This process employs a two-stage linkage pathway of "electrocatalytic oxidation + advanced oxidation" to achieve rapid removal and degradation of high-concentration organic matter and trace pollutants.

[0093] Unit 1: Electrocatalytic Oxidation Wastewater first passes through a screen and then enters an electrocatalytic oxidation tank. The tank is equipped with DSA anode plates (titanium-based IrO2 / RuO2 coated) and stainless steel cathode plates, arranged in parallel with a spacing of 10 mm. The oxidation process is carried out at a constant voltage of 12V and an average current density of 30 mA / cm². 2 Under certain conditions, it generates a strong oxidant through the anode, which rapidly destroys the emulsified oil film in the water, dissolves colloids, and partially degrades complex organic pollutants.

[0094] To enhance conductivity and free radical generation, sodium chloride (5 mg / L·NH3-N) was added as needed, while air was continuously introduced into the bottom aeration system (flow rate 15 L / min) to enhance oxygen participation and liquid phase disturbance, thereby increasing the reaction rate.

[0095] After electrocatalytic oxidation, pollutants undergo initial chain breaking and disruption, creating conditions for subsequent advanced oxidation stages.

[0096] Unit 2: Advanced Oxidation (UV / H2O2) The effluent flows by gravity into the advanced oxidation reaction tank, which is equipped with ultraviolet lamps (wavelength 254nm, irradiance ≥60mW / cm²). 2 Simultaneously, hydrogen peroxide (H2O2, concentration 40 mg / L) is added, and under UV irradiation, ·OH free radicals are generated in situ, further mineralizing intermediate organic products and trace pollutants in the water.

[0097] To avoid H2O2 waste and the adverse effects of residual oxidation byproducts on the effluent, the system is equipped with an online residual chlorine / oxygen monitoring probe to intelligently adjust the H2O2 dosing rate and ultraviolet light intensity.

[0098] The reaction time for this unit is set to 20 minutes to ensure that pollutants are fully degraded.

[0099] The overall processing results are as follows:

[0100] After treatment, the effluent is clear and transparent, with significantly reduced color and no obvious odor, meeting the Class I discharge limit requirements of the "Integrated Wastewater Discharge Standard".

[0101] It should be noted that, compared to Examples 1 and 2, the raw water quality in this example is significantly more complex and the pollution load is heavier, making it difficult for conventional chemical flocculation and membrane processes to handle efficiently. Through the combined pathway of "electrocatalysis + UV / H2O2", this process can achieve the synergistic degradation of multiple recalcitrant pollutants under non-biochemical conditions. It is particularly suitable for emergency response in highway service areas under extreme circumstances such as sudden emissions from catering establishments, concentrated emissions from vehicle washing, and temporary emission restrictions during inspections, providing technical support for the construction of modular, mobile, and rapid-response treatment devices.

[0102] This invention provides an emergency wastewater treatment process suitable for highway service areas. It constructs a short-process integrated system of "flocculation-membrane filtration-electrochemical oxidation", which has the advantages of compact structure, rapid start-up and stable effluent. It is suitable for rapid treatment to meet standards in sudden scenarios such as biochemical system failure, equipment abnormality or water quality change.

[0103] In this process, the flocculation unit effectively removes suspended solids and colloids, reducing membrane load; membrane filtration ensures clear and stable effluent; and the electrochemical oxidation unit further removes ammonia nitrogen and recalcitrant organic matter, eliminating the need for additional disinfection and ensuring effluent meets standards. This system does not rely on biochemical reactions, is highly efficient and automated, and is highly adaptable and practical, making it particularly suitable for service areas and other locations with high requirements for response speed and treatment effectiveness.

[0104] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An emergency treatment process for a highway service area sewage station, characterized in that, The method comprises the following steps: 1) introducing sewage into a flocculation tank for flocculation treatment, the flocculation tank being used for preliminary removal of suspended solids, organic matter and colloidal pollutants in the sewage, and the flocculation mode comprising chemical dosing flocculation or electrochemical flocculation; 2) introducing the sewage after flocculation treatment into a membrane filtration tank for solid-liquid separation, the membrane filtration tank being provided with an ultrafiltration membrane assembly for filtering flocculation particles; 3) conveying the sewage after membrane filtration to an electrochemical oxidation tank, the electrochemical oxidation tank being provided with an anode plate and a cathode plate, and electrolysis reaction being performed by applying voltage.

2. The emergency treatment process for a highway service area sewage station according to claim 1, characterized in that, The flocculation mode is chemical dosing flocculation, and a coagulant and a flocculant are added to the flocculation tank during the flocculation process, the coagulant being selected from polyaluminum chloride, aluminum sulfate or ferrous sulfate, and the flocculant being selected from polyacrylamide or chitosan.

3. The emergency treatment process for a highway service area sewage station according to claim 2, characterized in that, The addition amount of the coagulant is 50-150 mg / L, and the addition amount of the flocculant is 0.5-2.0 mg / L.

4. The emergency treatment process for a highway service area sewage station according to claim 3, characterized in that, In the flocculation tank, an adsorbent is also added, the adsorbent being selected from activated carbon, diatomite or bentonite, and the addition amount being 10-150 mg / L. The flocculation tank is provided with a dosing device and an aeration device, respectively used for proportionally and synchronously adding reagents and providing gas-liquid mixing to enhance flocculation body formation, and the hydraulic retention time of the flocculation tank is 15-60 minutes.

5. The emergency treatment process for a highway service area sewage station according to claim 4, characterized in that, The flocculation mode is electrochemical flocculation, metal ions are released in situ from an anode plate as a flocculant by setting the anode plate and a cathode plate and applying a direct current voltage, the anode plate being an aluminum plate or an iron plate, and the cathode plate being a stainless steel plate or a graphite plate.

6. The emergency treatment process for a highway rest area sewage station according to claim 1, characterized in that, The ultrafiltration membrane assembly in the membrane filtration tank is selected from ceramic membranes, flat sheet membranes or hollow fiber membranes, the membrane pore size is 0.02-0.2 microns, and a circulating pump and an aeration device are provided to slow down membrane pollution and improve filtration efficiency.

7. The emergency treatment process for a highway service area sewage station according to claim 6, characterized in that, The voltage between the anode and the cathode is 2-36 V, and the current density is 5-50 mA / cm 2 , and a flocculating agent is added in the electrochemical flocculation process.

8. Emergency treatment process for a motorway service area sewage station according to any one of claims 1-7, characterized in that, The anode plate of the electrochemical oxidation tank is a titanium-based metal oxide coating plate loaded with ruthenium and / or iridium, the cathode plate is a stainless steel plate or a titanium plate, the anode and the cathode are arranged in parallel to form a uniform electric field, and sodium chloride is added as an auxiliary electrolyte during electrolysis.

9. Emergency treatment process for a motorway service area sewage station according to any one of claims 1-7, characterized in that, ​ 10. The emergency treatment process for a highway service area sewage station according to claim 9, characterized in that, The adding amount of sodium chloride is 3-5 mg / L per 1 mg / L of ammonia nitrogen removed, the voltage between the anode and the cathode is 2-36 V, and the current density is 5-50 mA / cm 2 The electrochemical oxidation tank is provided with an aeration device and has a hydraulic retention time of 5-30 minutes, and a reflux channel is arranged between the membrane filtration tank and the flocculation tank for concentrated water circulation treatment.

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