Treatment system and method for coal-based solid waste harmless treatment wastewater

Abstract

The invention relates to the technical field of coal and coal chemical industry wastewater treatment, in particular to a treatment system and method for coal-based solid waste harmless treatment wastewater, and the system comprises an adjusting unit, a coagulating sedimentation unit, a catalytic ozonation unit, a gravity sedimentation unit, a biological filtration unit and a clean water tank unit; the adjusting unit is used for adjusting the water quality and the water quantity of the input wastewater; the coagulating sedimentation unit is used for removing sludge, suspended solids, colloidal particles and part of heavy metal pollutants in the wastewater; the ozone catalytic oxidation unit is used for removing refractory organic pollutants in the wastewater; the gravity precipitation unit is used for removing part of heavy metal pollutants in the wastewater and suspended solids, flocs and solid particles formed in the oxidation reaction process; the biological filtration unit is used for removing biochemical organic pollutants, part of suspended matters and part of inorganic pollutants in the wastewater; the clean water tank unit is used for collecting and storing filtered water; according to the invention, refractory organic matters and heavy metals in wastewater can be synergistically removed.

Description

Technical Field

[0001] This invention relates to the field of coal and coal chemical wastewater treatment technology, and in particular to a treatment system and method for harmless disposal of coal-based solid waste wastewater. Background Technology

[0002] The coal and coal chemical industry occupies an important position in my country's energy structure. During the coal production and coal gasification process, a large amount of solid waste such as coal gangue, coal gasification slag and furnace slag are generated. These wastes usually contain a certain amount of heavy metals. During the harmless disposal and backfilling process, heavy metals are prone to migration and release, posing a potential threat to the surrounding soil and groundwater environment.

[0003] Currently, harmless treatment technologies are being used to reduce the environmental risks of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.). These technologies involve rinsing and oxidizing the coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) to effectively remove heavy metals and organic pollutants.

[0004] However, the aforementioned harmless treatment process generates a large amount of wastewater. This type of wastewater is complex and usually contains excessive levels of heavy metals such as Al (aluminum), Zn (zinc), Fe (iron), and Ba (barium), along with persistent organic matter and inorganic salts. If directly discharged or improperly treated, it can pollute surface water, groundwater, and the ecological environment. At the same time, wastewater from the treatment of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) often contains a large amount of sludge, which easily forms a stable colloidal dispersion system, resulting in poor settling performance of suspended solids and difficulty in solid-liquid separation, thereby increasing the difficulty of wastewater treatment and reuse.

[0005] Existing industrial wastewater treatment technologies primarily target wastewater from coal chemical and coal washing industries, which can meet the treatment requirements of conventional coal production to a certain extent. However, wastewater generated during the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) is characterized by a high variety of heavy metals, the presence of recalcitrant organic matter, strong stability of sludge and fine suspended solids, and large fluctuations in water quality and quantity. There is a lack of targeted, complete treatment technologies, and related research and engineering applications remain limited. Existing industrial wastewater treatment technologies have the following shortcomings in practical applications: Firstly, existing methods for treating recalcitrant organic matter often employ advanced oxidation or enhanced treatment processes, primarily focusing on the chain breaking and degradation of organic pollutants. Strong oxidizing environments can cause changes in the valence state of some heavy metal ions, leading to alterations in their solubility and migration behavior, and increasing the uncertainty of subsequent treatment units. On the other hand, for heavy metals such as mercury, lead, cadmium, arsenic, and selenium in wastewater from coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), existing technologies mostly rely on chemical precipitation separation methods, which are easily affected by water quality fluctuations, making it difficult to guarantee the removal efficiency of heavy metals and the stability of effluent. In summary, existing coal chemical wastewater treatment technologies cannot simultaneously achieve efficient removal of multiple heavy metals, effective degradation of recalcitrant organic matter, efficient separation of sludge and residue, and recycling of water resources, thus restricting the reuse and resource utilization of wastewater from coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) to a certain extent. Summary of the Invention

[0006] The purpose of this invention is to provide a treatment system and method for harmless disposal of coal-based solid waste wastewater, which can solve the problems that existing industrial wastewater treatment technologies cannot achieve the synergistic removal of heavy metals and organic pollutants in wastewater from coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), and cannot solve the problems of difficult sedimentation and collection of sludge.

[0007] To address the aforementioned technical problems, this invention provides a treatment system for the harmless disposal of coal-based solid waste wastewater, comprising: a regulating unit, a coagulation and sedimentation unit, an ozone catalytic oxidation unit, a gravity sedimentation unit, a biological filtration unit, and a clear water tank unit connected in sequence; the regulating unit is used to regulate the water quality and quantity of the input wastewater; the coagulation and sedimentation unit is used to sequentially coagulate, flocculate, and settle the regulated wastewater to remove sludge, suspended solids, colloidal particles, and some heavy metal pollutants, thereby obtaining coagulated and settled wastewater; the ozone catalytic oxidation unit is used to treat the coagulated and settled wastewater with ozone and peroxide. Hydrogen catalytic oxidation is used to remove recalcitrant organic pollutants, resulting in wastewater treated by ozone catalytic oxidation. A gravity sedimentation unit is used to perform gravity sedimentation on the ozone-treated wastewater to remove some heavy metal pollutants, as well as suspended solids, flocs, and solid particles formed during the oxidation reaction, resulting in gravity-sedimented wastewater. A biological filtration unit is used to biodegrade and filter the gravity-sedimented wastewater to remove biodegradable organic pollutants, some suspended solids, and some inorganic pollutants, resulting in filtered water. A clear water tank unit is used to collect and store the filtered water.

[0008] Optionally, the coal-based solid waste harmless treatment wastewater treatment system provided by the present invention further includes a sludge treatment unit. The sludge treatment unit is connected to the regulating unit, the coagulation sedimentation unit, the gravity sedimentation unit, and the biological filtration unit, respectively. The sludge treatment unit is used to concentrate, dewater, and collect and transport the sludge generated by the coagulation sedimentation unit, the gravity sedimentation unit, and the biological filtration unit, and to transport the filtrate generated during the dewatering process to the regulating unit.

[0009] Optionally, the sludge treatment unit includes a sludge feeding device, a sludge dewatering device, a filtrate collection device, and a sludge discharge device. The sludge dewatering device includes at least one of a plate and frame filter press, a belt filter press, and a centrifugal dewatering machine.

[0010] Optionally, the adjustment unit includes an adjustment tank and a pH adjustment agent dosing device. The pH adjustment agent dosing device is used to add a pH adjustment agent to the adjustment tank. The pH adjustment agent includes at least one of sodium hydroxide, lime, and sodium carbonate. The adjustment tank is equipped with a first stirring device.

[0011] Optionally, the coagulation and sedimentation unit includes a coagulation and sedimentation tank, a coagulant dosing device, and a flocculant dosing device. The coagulation and sedimentation tank is provided with a coagulation zone, a flocculation zone, and a sedimentation reaction zone in sequence along the water flow direction. The coagulant dosing device is used to add coagulant to the coagulation zone, and the flocculant dosing device is used to add flocculant to the flocculation zone. A second stirring device is provided in the coagulation zone, and a third stirring device is provided in the flocculation zone. The coagulant includes at least one of polyaluminum chloride, polyferric sulfate, ferric chloride, and aluminum sulfate, and the flocculant includes at least one of anionic polyacrylamide, nonionic polyacrylamide, and cationic polyacrylamide.

[0012] Optionally, the ozone catalytic oxidation unit includes an ozone catalytic oxidation tank, an ozone generator and dosing device, a tail gas collection and treatment device, and a hydrogen peroxide dosing device. The ozone generator and dosing device is used to generate ozone to aerate the wastewater in the ozone catalytic oxidation tank. The tail gas collection and treatment device is used to collect and treat the ozone tail gas that has not participated in the reaction. The hydrogen peroxide dosing device is used to add hydrogen peroxide to the ozone catalytic oxidation tank. The ozone catalytic oxidation tank is equipped with a catalyst, which is a metal oxide catalyst or a supported catalyst with metal oxide as the active component supported on an inert support.

[0013] Optionally, the biological filtration unit includes a multi-stage aerated biological filter and a backwash effluent pipe connected to the multi-stage aerated biological filter. The multi-stage aerated biological filter is provided with a biological filter media layer, which includes at least one of a volcanic rock layer, a ceramsite layer, a quartz sand layer, an activated carbon layer, and a zeolite layer. The backwash effluent pipe is used to output the wastewater generated from cleaning the multi-stage aerated biological filter to the regulating unit.

[0014] Optionally, the clear water tank unit includes a clear water tank and an external discharge pipe, a reuse pipe, and a backwash water pipe connected to the clear water tank. The backwash water pipe is connected to the biological filtration unit and is used to transport the filtered water stored in the clear water tank to the biological filtration unit for cleaning the biological filtration unit.

[0015] To address the aforementioned technical problems, this invention also provides a method for treating wastewater from the harmless disposal of coal-based solid waste, applied to the aforementioned wastewater treatment system for harmless disposal of coal-based solid waste. The method includes: adjusting the quality and quantity of the input wastewater via an adjustment unit; sequentially performing coagulation, flocculation, and sedimentation on the adjusted wastewater via a coagulation and sedimentation unit to remove sludge, suspended solids, colloidal particles, and some heavy metal pollutants, thereby obtaining coagulated and sedimented wastewater; and subjecting the coagulated and sedimented wastewater to synergistic catalytic oxidation with ozone and hydrogen peroxide via an ozone catalytic oxidation unit. The process involves removing recalcitrant organic pollutants to obtain wastewater treated by ozone catalytic oxidation; gravity sedimentation of the ozone-catalytic oxidation wastewater removes some heavy metal pollutants, as well as suspended solids, flocs, and solid particles formed during the oxidation reaction, resulting in gravity-sedimented wastewater; biofiltration of the gravity-sedimented wastewater removes biodegradable organic pollutants, some suspended solids, and some inorganic pollutants, resulting in filtered water, which is then collected and stored in a clear water tank unit.

[0016] Optionally, the method further includes: adjusting the volumes of the regulating unit, the coagulation and sedimentation unit, the ozone catalytic oxidation unit, the gravity sedimentation unit, and the biological filtration unit respectively, to set the residence time of wastewater in the regulating unit, the coagulation and sedimentation unit, the ozone catalytic oxidation unit, the gravity sedimentation unit, and the biological filtration unit.

[0017] Compared with existing technologies, the treatment system and method for harmless disposal of coal-based solid waste wastewater provided by this invention have the following beneficial effects:

[0018] The coal-based solid waste harmless treatment wastewater treatment system provided by this invention includes a regulating unit, a coagulation and sedimentation unit, an ozone catalytic oxidation unit, a gravity sedimentation unit, a biological filtration unit, and a clear water tank unit connected in sequence. The regulating unit is used to adjust the water quality and quantity of the input wastewater. The coagulation and sedimentation unit is used to sequentially coagulate, flocculate, and settle the water after water quality adjustment to remove sludge, suspended solids, colloidal particles, and some heavy metal pollutants, thereby obtaining coagulated and settled wastewater. The ozone catalytic oxidation unit is used to perform synergistic catalysis of ozone and hydrogen peroxide on the coagulated and settled wastewater. The process involves several steps: First, oxidation is used to remove recalcitrant organic pollutants, resulting in wastewater treated with ozone catalytic oxidation. Second, a gravity sedimentation unit is used to perform gravity sedimentation on the ozone-treated wastewater to remove some heavy metal pollutants, as well as suspended solids, flocs, and solid particles formed during the oxidation reaction, resulting in gravity-sedimented wastewater. Third, a biological filtration unit is used to biodegrade and filter the gravity-sedimented wastewater to remove biodegradable organic pollutants, some suspended solids, and some inorganic pollutants, resulting in filtered water. Fourth, a clear water tank unit is used to collect and store the filtered water.

[0019] Therefore, the wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention is applicable to the treatment of wastewater from the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.). Specifically, in response to the characteristics of wastewater generated during the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), which contains a variety of heavy metals, contains recalcitrant organic matter, has strong stability of sludge and fine suspended solids, and has large fluctuations in water quality, a multi-unit collaborative wastewater treatment process system has been constructed. This system overcomes the problem that existing wastewater treatment technologies cannot simultaneously address the removal of heavy metals, degradation of organic matter, efficient removal of sludge, and water reuse, and has good applicability and specificity.

[0020] The wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention achieves graded removal of suspended solids, colloidal particles, heavy metal pollutants, and recalcitrant organic matter in wastewater through the coordinated operation of an adjustment unit, a coagulation and sedimentation unit, an ozone catalytic oxidation unit, a biological filtration unit, and a clear water tank unit. The treatment units complement and reinforce each other, effectively reducing the operating load of a single treatment unit, improving the overall treatment efficiency, ensuring long-term stable compliance of effluent quality, and enhancing the safety and reliability of system operation.

[0021] The wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention adopts a synergistic catalytic oxidation method using ozone and hydrogen peroxide. Under the action of the catalyst, hydroxyl radicals are generated to break chains, open rings, and mineralize the recalcitrant organic matter in the wastewater, significantly reducing the toxicity of the wastewater and improving its biodegradability. This creates favorable conditions for the stable operation of the subsequent biological filtration unit. The strong oxidizing environment causes some heavy metal ions in the wastewater to change their valence state, thereby altering the solubility of heavy metals and providing conditions for the removal of heavy metal ions in subsequent units. The biological filtration unit further removes biodegradable organic matter and some suspended solids through biodegradation and filtration, stabilizing the effluent quality of the system and improving the overall system's resistance to shock loads.

[0022] The coal-based solid waste harmless treatment wastewater treatment system provided by this invention achieves the recycling or standard discharge of coal-based solid waste (coal gangue, coal gasification slag and furnace slag, etc.) harmless treatment wastewater through the coordinated design of wastewater treatment and reuse, reducing the consumption of fresh water, and is particularly suitable for coal chemical enterprises concentrated in areas with relatively scarce water resources.

[0023] The method for treating wastewater from the harmless disposal of coal-based solid waste provided by this invention achieves the tiered removal of suspended solids, heavy metals, and recalcitrant organic matter in the wastewater through multi-unit synergistic and graded treatment. This significantly reduces the operating load of a single treatment unit and enables the recycling or compliant discharge of wastewater from the harmless disposal of coal-based solid waste, reducing fresh water consumption. It is suitable for areas with concentrated coal chemical enterprises where water resources are scarce and has good environmental and economic benefits. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a wastewater treatment system for the harmless disposal of coal-based solid waste provided in one embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the working process of a coal-based solid waste harmless treatment wastewater treatment system provided in one embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the coagulation and sedimentation unit of a wastewater treatment system for the harmless disposal of coal-based solid waste provided in one embodiment of the present invention.

[0027] Figure 4 A schematic diagram of the backwash water supply line of the clear water tank unit of the coal-based solid waste harmless treatment wastewater treatment system provided in one embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of the sludge treatment unit of a coal-based solid waste harmless treatment wastewater treatment system provided in one embodiment of the present invention.

[0029] Figure 6A flowchart of a sludge treatment method for a coal-based solid waste harmless treatment wastewater treatment system provided in one embodiment of the present invention.

[0030] The reference numerals in the attached figures are explained as follows:

[0031] 1-Adjustment Unit, 101-Adjustment Tank, 102-pH Adjuster Dosing Device, 103-First Stirring Device, 104-pH Adjuster Storage Tank, 105-pH Adjuster Dosing Pump, 2-Coagulation and Sedimentation Unit, 201-Coagulation and Sedimentation Tank, 202-Coagulant Dosing Device, 203-Flocculant Dosing Device, 204-Coagulation Zone, 205-Flocculation Zone, 206-Sedimentation Reaction Zone, 207-Coagulant Storage Tank, 208-Coagulant Dosing Pump, 209-Flocculant Storage Tank, 210-Flocculant Dosing Pump, 211-Second Stirring Device, 212-Third Stirring Device, 3-Ozone Catalytic Oxidation Unit, 301-Ozone Catalytic Oxidation 302-Ozone generator and dosing device, 303-Tail gas collection and treatment device, 304-Hydrogen peroxide dosing device, 305-Hydrogen peroxide storage tank, 306-Hydrogen peroxide dosing pump, 4-Gravity sedimentation unit, 401-Inclined plate sedimentation tank, 5-Biological filtration unit, 501-Multi-stage aerated biological filter, 502-Backwash effluent pipe, 6-Clear water tank unit, 601-Clear water tank, 602-External discharge pipeline, 603-Reuse pipeline, 604-Backwash water pipeline, 7-Sludge treatment unit, 701-Sludge feeding device, 702-Sludge dewatering device, 703-Filtrate collection device, 704-Sludge external discharge device, 8-Lift pump. Detailed Implementation

[0032] The treatment system and method for harmless disposal of coal-based solid waste wastewater proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. Please refer to the accompanying drawings for the objectives, features, and advantages of this invention to make them more apparent and understandable.

[0033] The core idea of ​​this invention is to provide a treatment system and method for harmless disposal of coal-based solid waste, so as to solve the problems that existing industrial wastewater treatment technologies cannot achieve the synergistic removal of heavy metals and organic pollutants in the disposal wastewater of coal-based solid waste (coal gangue, coal gasification slag and furnace slag, etc.), and cannot solve the problems of difficult sedimentation and collection of sludge.

[0034] To achieve the above-mentioned goals, this invention provides a treatment system for the harmless disposal of coal-based solid waste wastewater. Please refer to [the relevant documentation]. Figure 1 ,like Figure 1As shown, the wastewater treatment system for the harmless disposal of coal-based solid waste provided by the present invention includes: a regulating unit 1, a coagulation and sedimentation unit 2, an ozone catalytic oxidation unit 3, a gravity sedimentation unit 4, a biological filtration unit 5, and a clear water tank unit 6 connected in sequence; the regulating unit 1 is used to regulate the water quality and quantity of the input wastewater; the coagulation and sedimentation unit 2 is used to sequentially coagulate, flocculate, and settle the wastewater after water quality regulation to remove sludge, suspended solids, colloidal particles, and some heavy metal pollutants, thereby obtaining coagulated and settled wastewater; the ozone catalytic oxidation unit 3 is used to apply ozone and peroxidation to the coagulated and settled wastewater. Hydrogen-co-catalytic oxidation is used to remove recalcitrant organic pollutants, resulting in wastewater treated by ozone catalytic oxidation. The gravity sedimentation unit 4 is used to perform gravity sedimentation on the wastewater treated by ozone catalytic oxidation to remove some heavy metal pollutants, as well as suspended solids, flocs, and solid particles formed during the oxidation reaction, resulting in wastewater after gravity sedimentation. The biological filtration unit 5 is used to biodegrade and filter the wastewater after gravity sedimentation to remove biodegradable organic pollutants, some suspended solids, and some inorganic pollutants, resulting in filtered water. The clear water tank unit 6 is used to collect and store the filtered water.

[0035] Therefore, the wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention is applicable to the treatment of wastewater from the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.). Specifically, in response to the characteristics of wastewater generated during the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), which contains a variety of heavy metals, contains recalcitrant organic matter, has strong stability of sludge and fine suspended solids, and has large fluctuations in water quality, a multi-unit collaborative wastewater treatment process system has been constructed. This system overcomes the problem that existing wastewater treatment technologies cannot simultaneously address the removal of heavy metals, degradation of organic matter, efficient removal of sludge, and water reuse, and has good applicability and specificity.

[0036] Secondly, through the coordinated operation of the regulating unit 1, coagulation and sedimentation unit 2, ozone catalytic oxidation unit 3, gravity sedimentation unit 4, biological filtration unit 5, and clear water tank unit 6, the staged removal of suspended solids, colloidal particles, heavy metal pollutants, and recalcitrant organic matter in the wastewater is achieved. The treatment units complement and reinforce each other, effectively reducing the operating load of a single treatment unit, improving the overall treatment efficiency, ensuring that the effluent quality meets the standards in the long term, and enhancing the safety and reliability of the system operation.

[0037] Furthermore, the wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention adopts a synergistic catalytic oxidation method using ozone and hydrogen peroxide. Under the action of the catalyst, hydroxyl radicals are generated to break chains, open rings, and mineralize the recalcitrant organic matter in the wastewater, significantly reducing the toxicity of the wastewater and improving its biodegradability. This creates favorable conditions for the stable operation of the subsequent biological filtration unit 5. The strong oxidizing environment causes some heavy metal ions in the wastewater to change their valence state, thereby altering the solubility of heavy metals and providing conditions for the removal of heavy metal ions in subsequent units. The biological filtration unit 5 further removes biodegradable organic matter and some suspended solids through biodegradation and filtration, stabilizing the effluent quality of the system and improving the overall system's resistance to shock loads.

[0038] Finally, the wastewater treatment system for harmless disposal of coal-based solid waste provided by this invention achieves recycling or compliant discharge of wastewater from harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) through the coordinated design of wastewater treatment and reuse, reducing the consumption of fresh water. It is particularly suitable for areas with concentrated coal chemical enterprises where water resources are relatively scarce.

[0039] Please refer to Figure 2 and Figure 5 ,like Figure 2 and Figure 5 As shown, the coal-based solid waste harmless treatment wastewater treatment system provided by the present invention further includes a sludge treatment unit 7. The sludge treatment unit 7 is connected to the regulating unit 1, the coagulation sedimentation unit 2, the gravity sedimentation unit 4 and the biological filtration unit 5 respectively. The sludge treatment unit 7 is used to concentrate, dewater and collect the sludge produced by the coagulation sedimentation unit 2, the gravity sedimentation unit 4 and the biological filtration unit 5 for external transportation, and to transport the filtrate produced during the dewatering process to the regulating unit 1.

[0040] Therefore, this setup enables centralized collection and treatment of sludge generated by coagulation sedimentation unit 2, gravity sedimentation unit 4, and biological filtration unit 5, achieving sludge reduction and stabilization. By returning the dewatered filtrate to the regulating unit 1, the wastewater reuse rate can be improved.

[0041] Specifically, the sludge treatment unit 7 is used to concentrate, dewater, and collect and transport the sludge generated during the operation of the system, and the sludge feeding device 701 is used to receive the excess sludge generated from the coagulation sedimentation unit 2, the gravity sedimentation unit 4, and the biological filtration unit 5.

[0042] Please continue to refer to this. Figure 5 ,like Figure 5 As shown, the sludge treatment unit 7 includes a sludge feeding device 701, a sludge dewatering device 702, a filtrate collection device 703, and a sludge discharge device 704. The sludge dewatering device 702 includes at least one of a plate and frame filter press, a belt filter press, and a centrifugal dewatering machine.

[0043] Therefore, this setup enables centralized reduction and disposal of system sludge and filtrate recycling, effectively avoiding secondary pollution and improving wastewater utilization. In addition, the sludge dewatering device 702, by configuring at least one of a plate and frame filter press, a belt filter press, and a centrifugal dewatering machine, can flexibly select the optimal dewatering process for different sludge characteristics, significantly improving dewatering efficiency and cake solids content.

[0044] Specifically, the sludge feeding device 701 is used to receive the excess sludge produced by the coagulation sedimentation unit 2, gravity sedimentation unit 4 and biological filtration unit 5 and transport it to the sludge dewatering device 702. The sludge dewatering device 702 is used to mechanically separate the sludge into solid and liquid components to reduce its water content and form a sludge cake. The filtrate collection device 703 is used to collect the filtrate generated during the dewatering process and return it to the regulating unit 1 for further treatment. The sludge discharge device 704 is used to discharge the dewatered sludge cake from the coal-based solid waste harmless treatment wastewater treatment system provided by the present invention.

[0045] Please continue to refer to this. Figure 2 ,like Figure 2 As shown, the adjustment unit 1 includes an adjustment tank 101 and a pH adjustment agent dosing device 102. The pH adjustment agent dosing device 102 is used to add a pH adjustment agent to the adjustment tank 101. The pH adjustment agent includes at least one of sodium hydroxide, lime and sodium carbonate. The adjustment tank 101 is provided with a first stirring device 103.

[0046] Therefore, by setting up the pH adjustment agent dosing device 102, alkaline agents can be added to effectively adjust the pH value of wastewater. By using at least one of sodium hydroxide, lime or sodium carbonate as the pH adjustment agent, the optimal agent combination can be flexibly selected according to the wastewater characteristics and treatment costs, thereby reducing operating costs while ensuring that the pH value of wastewater is stably adjusted to a suitable range.

[0047] Furthermore, the regulating unit 1 serves as a pretreatment regulating unit, used to regulate the water quality and quantity of the input wastewater; it is equipped with a wastewater inlet for the harmless treatment of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), a wastewater inlet for backwashing of the biological filter, a waste liquid inlet for the sludge dewatering device, a pH adjusting agent dosing port, a first stirring device 103, and a wastewater outlet after water quality regulation. Furthermore, the wastewater originates from different treatment stages of coal-based solid waste harmless treatment. The different operating conditions of the pre-treatment processes lead to varying pollutant concentrations in the wastewater. For example, some treatment stages output wastewater with higher acid and heavy metal content, while others output wastewater with higher suspended sludge content. Therefore, it is necessary to balance the water quality and adjust the pH value in the regulating unit 1. Additionally, the flow rate of coal-based solid waste harmless treatment wastewater output from the gasification slag treatment system to the regulating tank 101 is uneven. Therefore, the regulating unit 1 adjusts the volume of the regulating tank 101 to set the hydraulic retention time, thereby balancing the wastewater flow. Alkaline agents are added to the equalization tank 101 through the pH adjustment agent inlet to adjust the pH value of the incoming water. The alkaline agents are preferably one or more of sodium hydroxide, lime, or sodium carbonate, providing suitable influent conditions for the subsequent treatment unit. At the same time, the wastewater in the equalization tank 101 is continuously stirred by the first stirring device 103, so that the coal-based solid waste harmless treatment wastewater with different pollutant concentrations is evenly mixed and the pH adjustment agent is evenly dissolved in the wastewater, accelerating the pH adjustment of the coal-based solid waste harmless treatment wastewater. The wastewater with the water quality adjusted and the flow rate is balanced is output to the coagulation sedimentation unit 2 for subsequent treatment.

[0048] Specifically, the pH adjuster dosing device 102 includes a pH adjuster storage tank 104 and a pH adjuster dosing pump 105; the pH adjuster dosing pump 105 transports the pH adjuster in the pH adjuster storage tank 104 to the equalization tank 101; the coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) harmless treatment wastewater inlet is used to input wastewater into the equalization tank 101, the biological filter backwash wastewater inlet is used to input biological filter backwash water into the equalization tank 101, and sludge... The wastewater inlet of the dewatering device is used to input the sludge filtrate produced by the sludge treatment unit 7 into the equalization tank 101. The pH adjuster dosing port is used for the pH adjuster dosing device 102 to add alkaline agent into the equalization tank 101. The wastewater outlet after water quality adjustment is connected to the lift pump 8 to pump the water quality adjusted wastewater to the coagulation sedimentation unit 2. The lift pump 8 is normally open and has a constant flow rate. The residence time of the wastewater in the equalization tank 101 can be changed by changing the volume of the equalization tank 101.

[0049] Please continue to refer to this. Figure 2 and Figure 3 ,like Figure 2 and Figure 3As shown, the coagulation and sedimentation unit 2 includes a coagulation and sedimentation tank 201, a coagulant dosing device 202, and a flocculant dosing device 203. The coagulation and sedimentation tank 201 is provided with a coagulation zone 204, a flocculation zone 205, and a sedimentation reaction zone 206 in sequence along the water flow direction. The coagulant dosing device 202 is used to add coagulant to the coagulation zone 204, and the flocculant dosing device 203 is used to add flocculant to the flocculation zone 205. A second stirring device 211 is provided in the coagulation zone 204, and a third stirring device 212 is provided in the flocculation zone 205. The coagulant includes at least one of polyaluminum chloride, polyferric sulfate, ferric chloride, and aluminum sulfate. The flocculant includes at least one of anionic polyacrylamide, nonionic polyacrylamide, and cationic polyacrylamide.

[0050] Therefore, this setup allows for the addition of coagulants and flocculants, and enables the flexible selection of the optimal agent for the wastewater, promoting the rapid formation of flocs and effective sedimentation and separation of suspended solids, colloidal particles, and some heavy metal pollutants in the wastewater.

[0051] Furthermore, the coagulation sedimentation tank 201 is sequentially provided with a coagulation zone 204, a flocculation zone 205, and a sedimentation reaction zone 206 along the water flow direction. The coagulation zone 204 is equipped with a wastewater inlet after water quality adjustment, a coagulant dosing port, a coagulant dosing device 202, and a second stirring device 211. The flocculation zone 205 is equipped with a flocculant dosing port, a flocculant dosing device 203, and a third stirring device 212. The sedimentation reaction zone 206 is equipped with a second outlet and a sludge discharge port. Specifically, the coagulant dosing device 202 includes a coagulant storage tank 207 and a coagulant dosing pump 208. The coagulant dosing device 203 includes a flocculant storage tank 209 and a flocculant dosing pump 210; the wastewater inlet after water quality adjustment is used to input the wastewater after water quality adjustment into the coagulation sedimentation tank 201; the coagulant dosing port and the flocculant dosing port are used to add coagulant and flocculant to the coagulation sedimentation tank 201; the coagulant dosing device 202 and the flocculant dosing device 203 are used to add coagulant and flocculant; the coagulation zone 204 is mechanically or hydraulically stirred by the second stirring device 211; and the flocculation zone 205 is stirred at low speed by the third stirring device 212.

[0052] The coagulant is preferably one or more of the inorganic polymeric coagulants such as polyaluminum chloride (PAC), polyferric sulfate (PFS), ferric chloride (FeCl3), and aluminum sulfate, used to disrupt the stable structure of colloidal particles in wastewater; the flocculant is preferably anionic polyacrylamide (APAM), nonionic polyacrylamide (NPAM), cationic polyacrylamide (CPAM), etc., used to promote the bridging and growth of micro-flocs.

[0053] The coagulation and sedimentation unit 2 promotes the formation of flocs from suspended solids and colloidal particles in wastewater through coagulation, flocculation, and sedimentation, thereby achieving solid-liquid separation and removing some heavy metal pollutants, thus reducing the treatment load of subsequent treatment units.

[0054] Please continue to refer to this. Figure 2 ,like Figure 2 As shown, the ozone catalytic oxidation unit 3 includes an ozone catalytic oxidation tank 301, an ozone generator and dosing device 302, a tail gas collection and treatment device 303, and a hydrogen peroxide dosing device 304. The ozone generator and dosing device 302 is used to generate ozone to aerate the wastewater in the ozone catalytic oxidation tank 301. The tail gas collection and treatment device 303 is used to collect and treat the ozone tail gas that has not participated in the reaction. The hydrogen peroxide dosing device 304 is used to add hydrogen peroxide to the ozone catalytic oxidation tank 301. The ozone catalytic oxidation tank 301 is equipped with a catalyst, which is a metal oxide catalyst or a supported catalyst with metal oxide as the active component supported on an inert support.

[0055] Therefore, this setup enables the synergistic catalytic oxidation of ozone and hydrogen peroxide, as well as the safe treatment of exhaust gases.

[0056] Furthermore, the ozone catalytic oxidation tank 301 is equipped with a wastewater inlet after coagulation and sedimentation, an ozone contact zone, a catalytic reaction zone, a mixing reaction zone, a wastewater outlet after ozone catalytic oxidation treatment, an ozone generation and dosing device 302, a hydrogen peroxide dosing device 304, and a tail gas collection and treatment device 303, for catalytic oxidation treatment of wastewater; the ozone catalytic oxidation unit 3 adopts a synergistic catalytic oxidation method of ozone and hydrogen peroxide, generating hydroxyl radicals (·OH) under the action of a catalyst, which perform chain breaking, ring opening, and mineralization reactions on the recalcitrant organic matter in the wastewater, achieving effective removal of organic pollutants, reducing wastewater toxicity, and improving its biodegradability, thereby providing stable influent conditions for subsequent deep treatment or reuse; the strong oxidizing environment will cause some heavy metal ions in the wastewater to change their valence state, thereby changing the solubility of heavy metals, providing conditions for the removal of heavy metal ions in subsequent units; the ozone generation and dosing device 302, preferably one or more of corona discharge ozone generators and ultraviolet ozone generators, aerates the ozone catalytic oxidation tank 301 through one or more of jet injection, venturi device injection, or microporous aeration, for adding ozone to the wastewater to provide the oxidant required for the catalytic oxidation reaction; the hydrogen peroxide injection device 304 includes a hydrogen peroxide storage tank 305 and a hydrogen peroxide injection pump 306, preferably including one or more of a metering pump injection system and a gravity injection system, for adding hydrogen peroxide to the ozone catalytic oxidation tank 301 according to a set injection amount, so as to react with ozone to generate hydroxyl radicals; the tail gas collection and treatment device 303 preferably includes one or more of an ozone tail gas destroyer, an activated carbon adsorption device, or a catalytic decomposition device, for collecting and treating the ozone tail gas that did not participate in the reaction during the reaction process, preventing ozone leakage and ensuring the safe operation of the system.

[0057] Specifically, the wastewater inlet after coagulation and sedimentation is used to input the coagulated and settled wastewater into the ozone catalytic oxidation tank 301; the ozone contact zone is used to achieve initial contact and mixing between ozone and wastewater, providing an initial oxidation environment for the catalytic oxidation reaction; the catalytic reaction zone is used to promote the decomposition of ozone to generate hydroxyl radicals under the action of a catalyst, and to carry out chain breaking, ring opening and mineralization reactions on the recalcitrant organic matter in the wastewater; the mixing reaction zone is used to achieve full mixing and synergistic effect of ozone and hydrogen peroxide, and to enhance the generation and oxidation reaction efficiency of hydroxyl radicals; the wastewater outlet after ozone catalytic oxidation treatment is used to transport the catalytically oxidized wastewater to the subsequent treatment unit.

[0058] Furthermore, the catalyst is preferably a metal oxide catalyst, or a supported catalyst in which a metal oxide is the active component supported on an inert support, including but not limited to one or more of manganese oxide, iron oxide, aluminum oxide, copper oxide, and cobalt oxide, or a supported catalyst in which the above metal oxides are supported on a support.

[0059] For further details, please refer to... Figure 2 ,like Figure 2 As shown, the gravity sedimentation unit 4 is located after the coagulation sedimentation unit 2 or the ozone catalytic oxidation unit 3. The gravity sedimentation unit 4 includes an inclined plate sedimentation tank 401, which is provided with an inlet water distribution area, a sedimentation area and an outlet water collection area. The bottom of the sedimentation area is provided with a sludge discharge area, which is connected to the sludge treatment unit 7 through a sludge discharge system. It is used to separate suspended solids, flocs and solid particles generated by the reaction in the treated wastewater by gravity sedimentation. Through sedimentation, the gravity sedimentation unit 4 can further remove suspended solids and some heavy metal pollutants from the wastewater, thereby reducing the load on subsequent treatment units and stabilizing the effluent quality.

[0060] Specifically, the inlet water distribution zone is used to evenly distribute wastewater to the sedimentation zone to ensure stable water flow; the sedimentation zone is used to separate suspended solids, flocs, and solid particles by gravity settling and inclined plate interception; the effluent collection zone is used to collect the supernatant after sedimentation and export it to the subsequent treatment unit; the sludge discharge zone is used to collect and temporarily store the sludge deposited at the bottom of the sedimentation zone; and the sludge discharge system is used to transport the sludge from the sludge discharge zone to the sludge treatment unit 7 for further treatment.

[0061] Please continue to refer to this. Figure 2 ,like Figure 2 As shown, the biological filtration unit 5 includes a multi-stage aerated biological filter 501 and a backwash outlet pipe 502 connected to the multi-stage aerated biological filter 501. The multi-stage aerated biological filter 501 is provided with a biological filter media layer, which includes at least one of a volcanic rock layer, a ceramsite layer, a quartz sand layer, an activated carbon layer, and a zeolite layer. The backwash outlet pipe 502 is used to output the wastewater generated from cleaning the multi-stage aerated biological filter 501 to the regulating unit 1.

[0062] Therefore, by setting up a multi-stage aerated biological filter 501, the dissolved oxygen distribution and microbial community structure can be optimized through staged oxygen supply and staged biological reaction, thereby improving oxygen utilization efficiency and biodegradation effect. At the same time, by selecting at least one of volcanic rock, ceramsite, quartz sand, activated carbon and zeolite as the biological filter media layer, the characteristics of large specific surface area, high porosity, good mechanical strength and strong chemical stability of the filter media can be fully utilized. This not only provides an excellent attachment carrier for microbial growth and forms a stable biofilm system, but also enables the filter media to perform adsorption and retention functions.

[0063] Furthermore, the multi-stage aerated biological filter 501 is equipped with a biological filter media layer, a water distribution device, an aeration device, and an effluent device. Through biodegradation and filtration, it further reduces the concentration of organic pollutants in the wastewater, removes some suspended solids, and stabilizes the effluent quality, providing conditions for subsequent advanced treatment or reuse. The biological filtration unit 5 adopts the form of an aerated biological filter, preferably a multi-stage aerated biological filter 501, to achieve graded oxygen supply and segmented biological reaction. The biological filter media layer is used for the attachment and growth of microorganisms, which remove biodegradable organic matter and some inorganic pollutants in the wastewater through microbial metabolism. The aeration device is used to supply oxygen to the multi-stage aerated biological filter 501 to maintain the conditions for microbial growth and biological reaction.

[0064] Specifically, the water distribution device is used to evenly distribute the influent to the biological filter media layer to ensure uniform hydraulic load; the aeration device is used to provide oxygen to the tank to maintain the dissolved oxygen conditions required for microbial growth and biological reactions; and the effluent device is used to collect the effluent after biodegradation and filtration and export it to subsequent units.

[0065] For further details, please refer to... Figure 4 ,like Figure 4 As shown, the backwash outlet pipe 502 is used to transport the sewage generated during the backwashing process of the multi-stage aerated biological filter 501 back to the regulating unit 1 for further treatment, thereby realizing a closed-loop circulation of water resources within the system.

[0066] Please refer to Figure 2 and Figure 4 ,like Figure 2 and Figure 4 As shown, the clear water tank unit 6 includes a clear water tank 601 and an external discharge pipe 602, a reuse pipe 603, and a backwash water pipe 604 connected to the clear water tank 601. The backwash water pipe 604 is connected to the biological filtration unit 5 and is used to transport the filtered water stored in the clear water tank 601 to the biological filtration unit 5 to clean the biological filtration unit 5.

[0067] Therefore, this setup allows for the discharge of compliant water or its reuse in production, while ensuring the self-use water needs for backwashing of the biological filter and reducing the consumption of fresh water.

[0068] Furthermore, the clear water tank unit 6, as the end-of-system regulation and storage unit, is located after the biological filtration unit 5. It is used to collect, store, and regulate the treated effluent to achieve the standard discharge of wastewater and reuse of the system, thereby meeting the water demand under different operating conditions and improving the comprehensive utilization efficiency of water resources. The clear water tank unit 6 is equipped with an inlet, a reused water outlet, a backwash water outlet, an overflow outlet, a drain outlet, and a liquid level control device.

[0069] Specifically, the inlet is used to receive and introduce the effluent treated by the biological filtration unit 5; the recycled water outlet is used to transport the stored qualified water to the reuse system for production reuse; the backwash water outlet is used to transport the stored water to the biological filtration unit 5 to provide backwash water; the overflow outlet is used to automatically overflow when the liquid level exceeds the set height to ensure the safe operation of the tank; the drain outlet is used to drain the water accumulated in the tank during maintenance or cleaning; and the liquid level control device is used to monitor and adjust the water level in the clear water tank 601 to ensure the stable operation and automatic control of the system.

[0070] Based on the same inventive concept, this invention also provides a method for treating wastewater from the harmless treatment of coal-based solid waste, applied to the aforementioned wastewater treatment system for the harmless treatment of coal-based solid waste. Please refer to [reference needed]. Figure 6 ,like Figure 6 As shown, the method includes: step S100, adjusting the water quality and quantity of the input wastewater through adjustment unit 1; step S200, sequentially performing coagulation, flocculation, and sedimentation on the water quality-adjusted wastewater through coagulation and sedimentation unit 2 to remove sludge, suspended solids, colloidal particles, and some heavy metal pollutants, thereby obtaining coagulated and settled wastewater; step S300, subjecting the coagulated and settled wastewater to ozone and hydrogen peroxide synergistic catalytic oxidation through ozone catalytic oxidation unit 3 to remove recalcitrant organic pollutants, thereby obtaining ozone catalytic oxidation treatment. The wastewater after ozone catalytic oxidation treatment is subjected to gravity sedimentation in the gravity sedimentation unit 4 to remove some heavy metal pollutants and suspended solids, flocs and solid particles formed during the oxidation reaction, thereby obtaining gravity-sedimented wastewater; in step S500, the gravity-sedimented wastewater is subjected to biodegradation and filtration in the biological filtration unit 5 to remove biodegradable organic pollutants, some suspended solids and some inorganic pollutants, thereby obtaining filtered water, which is then collected and stored in the clear water tank unit 6.

[0071] Therefore, the method for treating coal-based solid waste harmless disposal wastewater provided by the present invention achieves the tiered removal of suspended solids, heavy metals and recalcitrant organic matter in wastewater through multi-unit synergistic graded treatment, significantly reducing the operating load of a single treatment unit, and also enabling the recycling or compliant discharge of coal-based solid waste harmless disposal wastewater, reducing fresh water consumption. It is particularly suitable for areas with concentrated coal chemical enterprises where water resources are scarce, and has good environmental and economic benefits.

[0072] Furthermore, the ozone catalytic oxidation unit 3 aerates ozone into the coagulated and settled wastewater through jet injection, venturi device injection, or microporous aeration.

[0073] Therefore, this setup allows for flexible selection of the optimal gas-liquid mixing mode based on the wastewater's characteristics and treatment scale. It utilizes the high-speed turbulent shearing effect generated by jet or Venturi devices to form microbubbles, or generates uniform small bubbles through microporous aeration. This significantly increases the gas-liquid contact area and mass transfer driving force, improves the ozone's dissolution efficiency and utilization rate in water, ensures sufficient contact between ozone and wastewater and its rapid participation in catalytic oxidation reactions, thereby enhancing the generation efficiency of hydroxyl radicals, improving the ability to oxidize and decompose recalcitrant organic matter, while reducing ozone dosage and exhaust gas generation, and lowering operating energy consumption and treatment costs.

[0074] Furthermore, the method also includes: adjusting the volumes of the regulating unit 1, the coagulation and sedimentation unit 2, the ozone catalytic oxidation unit 3, the gravity sedimentation unit 4, and the biological filtration unit 5 respectively, so as to set the residence time of wastewater in the regulating unit 1, the coagulation and sedimentation unit 2, the ozone catalytic oxidation unit 3, the gravity sedimentation unit 4, and the biological filtration unit 5.

[0075] Therefore, by adjusting the effective volume of each treatment unit, the hydraulic retention time can be flexibly set and precisely controlled. This not only allows for proactive adjustment of the reaction time of each process step according to the dynamic changes in the quality and quantity of coal-based solid wastewater, but also effectively balances the wastewater flow distribution within the system through volume adjustment, avoiding problems such as short-circuiting, dead zones, and hydraulic shocks. This significantly improves the system's adaptability to complex water quality fluctuations and its operational stability.

[0076] Specifically, the volumes of equalization tank 101, coagulation sedimentation tank 201, ozone catalytic oxidation tank 301, inclined plate sedimentation tank 401, and multi-stage aerated biological filter 501 can all be actively adjusted.

[0077] The treatment system and method for harmless disposal of coal-based solid waste wastewater provided by the present invention will be described in detail below with reference to Examples 1 and 2.

[0078] Example 1:

[0079] Wastewater generated during the harmless treatment of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.) enters the regulating unit 1. At the same time, backwash wastewater from the biological filtration unit 5 and filtrate generated during the dewatering process of the sludge treatment unit 7 also enter the regulating unit 1 for water quantity and quality regulation.

[0080] The regulating unit 1 balances the incoming water volume by setting the hydraulic retention time and is equipped with a first stirring device 103. By adding alkaline agents to the regulating tank 101 and stirring, the water quality of the wastewater is adjusted so that the wastewater quality meets the influent requirements of the subsequent treatment unit. The hydraulic retention time is set according to the influent water volume and water quality fluctuations, preferably from 1 hour to 6 hours.

[0081] The effluent from regulating unit 1 is pumped to coagulation sedimentation tank 201 by lift pump 8 for further treatment.

[0082] The coagulation and sedimentation unit 2 is sequentially configured with a coagulation zone 204, a flocculation zone 205, and a sedimentation reaction zone 206 along the water flow direction. In the coagulation zone 204, a coagulant is added to the wastewater and rapidly stirred at a speed preferably between 200 and 500 r / min. In the flocculation zone 205, slow stirring is performed to promote floc growth at a speed preferably between 30 and 100 r / min. The wastewater then enters the sedimentation reaction zone 206 for solid-liquid separation, removing suspended solids, colloidal particles, and some heavy metal pollutants. The hydraulic retention time in the coagulation and sedimentation unit 2 is preferably between 1.5 and 2.5 hours. The coagulant is preferably one or more of polyaluminum chloride and polyferric sulfate. The sludge produced during sedimentation is discharged into the sludge treatment unit 7, and the supernatant enters the ozone catalytic oxidation unit 3.

[0083] The effluent from coagulation and sedimentation unit 2 enters ozone catalytic oxidation unit 3.

[0084] The ozone catalytic oxidation unit 3 is equipped with an ozone generator and dosing device 302, a hydrogen peroxide dosing device 304, a reaction zone, and a tail gas collection and treatment device 303. During the reaction, ozone is generated by the ozone generator and aerated using one or more of the following methods: jet dosing, venturi dosing, or microporous aeration. Simultaneously, hydrogen peroxide is added to the reaction zone, generating hydroxyl radicals under the action of a catalyst. The reaction process involves chain breaking, ring opening, and mineralization reactions of recalcitrant organic matter in wastewater, thereby reducing wastewater toxicity and improving its biodegradability. The strong oxidizing environment causes some heavy metal ions in the wastewater to change their valence state, thus altering their solubility. The catalyst is preferably a metal oxide catalyst, or a supported catalyst with metal oxides as the active component on an inert support, including but not limited to one or more of manganese oxides, iron oxides, aluminum oxides, copper oxides, and cobalt oxides, or supported catalysts with the above-mentioned metal oxides on a support. The hydraulic retention time is preferably 1 to 3 hours. Ozone tail gas that does not participate in the reaction is treated by tail gas collection and treatment device 303 before being discharged.

[0085] The wastewater treated by ozone catalytic oxidation is lifted to gravity sedimentation unit 4 by booster pump 8.

[0086] Wastewater undergoes solid-liquid separation through gravity settling in gravity sedimentation unit 4. The sludge produced by sedimentation is discharged through the sludge discharge port and enters the sludge treatment system for unified treatment. The supernatant enters the biological filtration unit 5 for biological treatment. The hydraulic retention time is preferably 1 to 1.5 hours.

[0087] The water from gravity sedimentation unit 4 enters biological filtration unit 5.

[0088] The biological filtration unit 5 adopts the form of an aerated biological filter, preferably a multi-stage aerated biological filter 501, to achieve graded oxygen supply and staged biological reaction. The hydraulic load of the aerated biological filter is preferably 1.0. Up to 4.0 The hydraulic retention time is preferably 3 to 6 hours. The aeration method is bottom aeration, and the aeration intensity is preferably 5. Up to 15 The preferred dissolved oxygen concentration is 2 Up to 4 The biological filter media layer is preferably one or more of volcanic rock, ceramsite, quartz sand, activated carbon, and zeolite. The filter media particle size is preferably 3mm to 8mm, and the filter media layer height is preferably 0.5m to 3.5m. Wastewater flows through the biological filter media layer in a predetermined flow direction. Microorganisms attached to the filter media surface biodegrade the biodegradable organic matter in the wastewater, removing some suspended solids through filtration, thus further stabilizing the effluent quality. When the operating resistance of the biological filter media layer increases and reaches a predetermined threshold, filtration stops, and the biological filter unit 5 is backwashed with clean water from the clear water tank unit 6. The wastewater generated from the backwash is returned to the regulating unit 1 for unified treatment.

[0089] The effluent from biological filtration unit 5 enters clear water tank unit 6.

[0090] The clear water tank unit 6 serves as the end-of-system regulation and storage unit, used for collecting, temporarily storing, and regulating the volume of treated effluent. The clear water tank unit 6 is equipped with an inlet, an outlet, an overflow outlet, and a level control device. The inlet is connected to the outlet of the biological filtration unit 5 to receive the treated effluent; the level control device regulates the water level in the clear water tank 601 to prevent overflow or empty tank operation; the overflow outlet ensures safe overflow under abnormal operating conditions.

[0091] The effluent from the clear water tank unit 6 can be used for one or more of the following purposes, depending on operational needs: to meet discharge standards, reuse in the harmless treatment section of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), for equipment flushing, for other production auxiliary water, or for the wastewater treatment system itself. This improves the comprehensive utilization efficiency of water resources and enhances the operational stability of the system.

[0092] The sludge generated during the operation of the coagulation sedimentation unit 2, gravity sedimentation unit 4, and biological filtration unit 5 is pumped to the sludge treatment unit 7. The sludge first enters the sludge conditioning device, where conditioning agents are added to improve the sludge dewatering performance. Then, it enters the dewatering device for solid-liquid separation to obtain sludge residue and filtrate. The dewatering device can be a plate and frame filter press, a belt filter press, or centrifugal dewatering. The filtrate generated from dewatering is returned to the conditioning unit 1 for treatment, and the dewatered sludge residue is transported off-site.

[0093] The treatment system and method for harmless disposal of coal-based solid waste provided in Example 1 above can achieve the synergistic removal of suspended solids, heavy metals and recalcitrant organic matter in the harmless disposal wastewater of coal-based solid waste (coal gangue, coal gasification slag and furnace slag, etc.), while realizing the reduction of sludge discharge and wastewater recycling. The system operates stably, has strong engineering feasibility, and is suitable for the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag and furnace slag, etc.).

[0094] Example 2:

[0095] A coal chemical plant generates wastewater during the harmless treatment of coal gasification slag. The wastewater is introduced into the coal-based solid waste harmless treatment wastewater treatment system provided by this invention for treatment. The test results of the influent and effluent water quality of the system are shown in Table 1.

[0096] Experimental conditions:

[0097] (1) Influent water quality conditions, as shown in Table 1.

[0098] (2) Adjustment unit 1, hydraulic residence time is 1h.

[0099] (3) Coagulation and sedimentation unit 2, the coagulant is polyaluminum chloride (PAC), and the hydraulic retention time is 2h.

[0100] (4) Ozone catalytic oxidation unit 3, pH 6 to 8, ozone concentration 55 , The concentration is 30%, and the dosage is 0.25%. The catalyst is Small ball, throwing amount is The hydraulic residence time is 3 hours.

[0101] (5) Gravity sedimentation unit 4, hydraulic residence time is 1.5h.

[0102] (6) Biofiltration unit 5, pH 6 to 8, temperature 20°C The filter media is made of volcanic rock, the filter bed height is 2.0m, and the hydraulic load is 3.0. The hydraulic residence time is 3 hours.

[0103] The following table (Table 1) shows the influent and effluent water quality test results of the coal-based solid waste harmless treatment wastewater treatment system provided by this invention. :

[0104]

[0105] Experimental results show that after treatment by the wastewater treatment system for harmless disposal of coal-based solid waste provided by this invention, all indicators of the effluent water quality meet the Class III water quality requirements of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0106] The wastewater, after treatment by the wastewater treatment system for the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), has an effluent chemical oxygen demand (COD) of 17.32. 20 below the Class III standard limit for surface water The ammonia nitrogen concentration in the effluent was 0.007. It is 1.0 below the Class III standard limit for surface water. Regarding heavy metal indicators, the mercury (Hg) concentration in the effluent was 0.091. Selenium (Se) was not detected, and lead (Pb) was 0.818. The chromium (Cr) content is 39.872. The cadmium (Cd) content is 0.011. Arsenic (As) content was 4.297. The zinc (Zn) content is 4.527. The value of copper (Cu) is 1.872. All of the above indicators meet the requirements of the Class III surface water quality standard limit.

[0107] In summary, the wastewater treatment method for the harmless disposal of coal-based solid waste provided by this invention can effectively remove organic pollutants and heavy metal pollutants from the wastewater generated during the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.). The treated effluent quality stably meets the Class III surface water standard and is suitable for discharge and reuse.

[0108] Compared with existing technologies, the treatment system and method for harmless disposal of coal-based solid waste wastewater provided by this invention have the following beneficial effects:

[0109] The wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention is applicable to the treatment of wastewater from the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.). Specifically, in response to the characteristics of wastewater generated during the harmless disposal of coal-based solid waste (coal gangue, coal gasification slag, and furnace slag, etc.), which contains a variety of heavy metals, contains recalcitrant organic matter, has strong stability of sludge and fine suspended solids, and has large fluctuations in water quality, a multi-unit collaborative wastewater treatment process system has been constructed. This system overcomes the problem that existing wastewater treatment technologies cannot simultaneously address the removal of heavy metals, degradation of organic matter, efficient removal of sludge, and water reuse, and has good applicability and specificity.

[0110] The wastewater treatment system for the harmless disposal of coal-based solid waste provided by this invention achieves graded removal of suspended solids, colloidal particles, heavy metal pollutants, and recalcitrant organic matter in wastewater through the coordinated operation of the regulating unit 1, coagulation and sedimentation unit 2, ozone catalytic oxidation unit 3, biological filtration unit 5, and clear water tank unit 6. The treatment units complement and reinforce each other, effectively reducing the operating load of a single treatment unit, improving the overall treatment efficiency, ensuring long-term stable compliance of effluent quality, and enhancing the safety and reliability of system operation.

[0111] The wastewater treatment system for harmless disposal of coal-based solid waste provided by this invention adopts a synergistic catalytic oxidation method of ozone and hydrogen peroxide. Under the action of the catalyst, hydroxyl radicals are generated to break the chains, open the rings, and mineralize the recalcitrant organic matter in the wastewater, significantly reducing the toxicity of the wastewater and improving its biodegradability. This creates favorable conditions for the stable operation of the subsequent biological filtration unit 5. The strong oxidizing environment causes some heavy metal ions in the wastewater to change their valence state, thereby changing the solubility of heavy metals and providing conditions for the removal of heavy metal ions in subsequent units. The biological filtration unit 5 further removes biodegradable organic matter and some suspended solids through biodegradation and filtration, stabilizing the effluent quality of the system and improving the overall shock load resistance of the system.

[0112] The coal-based solid waste harmless treatment wastewater treatment system provided by this invention achieves the recycling or standard discharge of coal-based solid waste (coal gangue, coal gasification slag and furnace slag, etc.) harmless treatment wastewater through the coordinated design of wastewater treatment and reuse, reducing the consumption of fresh water, and is particularly suitable for coal chemical enterprises concentrated in areas with relatively scarce water resources.

[0113] The method for treating wastewater from the harmless disposal of coal-based solid waste provided by this invention achieves the tiered removal of suspended solids, heavy metals, and recalcitrant organic matter in the wastewater through multi-unit synergistic and graded treatment. This significantly reduces the operating load of a single treatment unit and enables the recycling or compliant discharge of wastewater from the harmless disposal of coal-based solid waste, reducing the consumption of fresh water. It is particularly suitable for areas with concentrated coal chemical enterprises where water resources are scarce, and has good environmental and economic benefits.

[0114] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A coal-based solid waste innocuity disposal wastewater treatment system, characterized in that, The application relates to a wastewater treatment device. The device comprises a regulating unit, a coagulation and sedimentation unit, an ozone catalytic oxidation unit, a gravity sedimentation unit, a biological filtration unit and a clear water pool unit which are sequentially connected. The regulating unit is used for regulating the water quality and water quantity of input wastewater. The coagulation and sedimentation unit is used for sequentially coagulating, flocculating and precipitating the wastewater after water quality regulation, so as to remove sludge, suspended solids, colloidal particles and part of heavy metal pollutants, thereby obtaining wastewater after coagulation and sedimentation. The ozone catalytic oxidation unit is used for catalytically oxidizing the wastewater after coagulation and sedimentation by ozone and hydrogen peroxide, so as to remove refractory organic pollutants, thereby obtaining wastewater after ozone catalytic oxidation treatment. The gravity sedimentation unit is used for gravity sedimentation of the wastewater after ozone catalytic oxidation treatment, so as to remove part of heavy metal pollutants and suspended solids, floccules and solid particles formed in the oxidation process, thereby obtaining wastewater after gravity sedimentation. The biological filtration unit is used for biodegradation and filtration of the wastewater after gravity sedimentation, so as to remove biodegradable organic pollutants, part of suspended solids and part of inorganic pollutants, thereby obtaining filtered water. The clear water pool unit is used for collecting and storing the filtered water.

2. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 1, characterized in that, The device further comprises a sludge treatment unit which is connected with the regulating unit, the coagulation and sedimentation unit, the gravity sedimentation unit and the biological filtration unit, respectively.

3. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 2, characterized in that, The sludge treatment unit is used for concentrating, dewatering and collecting and transporting sludge generated by the coagulation and sedimentation unit, the gravity sedimentation unit and the biological filtration unit, and conveying filtrate generated in the dewatering process to the regulating unit.

4. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 1, characterized in that, The sludge treatment unit comprises a sludge feeding device, a sludge dewatering device, a filtrate collecting device and a sludge discharging device.

5. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 1, characterized in that, The regulating unit comprises a regulating pool and a pH adjusting agent adding device which is used for adding a pH adjusting agent to the regulating pool. The pH adjusting agent comprises at least one of sodium hydroxide, lime and sodium carbonate. The coagulation and sedimentation unit comprises a coagulation and sedimentation pool, a coagulant adding device and a flocculant adding device. The coagulation and sedimentation pool is sequentially provided with a coagulation zone, a flocculation zone and a sedimentation reaction zone along the water flow direction. The coagulant adding device is used for adding a coagulant to the coagulation zone. The flocculant adding device is used for adding a flocculant to the flocculation zone. The coagulant comprises at least one of polyaluminum chloride, polyferric sulfate, ferric chloride and aluminum sulfate. The flocculant comprises at least one of anionic polyacrylamide, nonionic polyacrylamide and cationic polyacrylamide.

6. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 1, characterized in that, The ozone catalytic oxidation unit comprises an ozone catalytic oxidation tank, an ozone generation and adding device, a tail gas collection and treatment device and a hydrogen peroxide adding device, the ozone generation and adding device is used to generate ozone to perform ozone aeration on the wastewater in the ozone catalytic oxidation tank, the tail gas collection and treatment device is used to collect and treat the ozone tail gas which does not participate in the reaction, and the hydrogen peroxide adding device is used to add hydrogen peroxide into the ozone catalytic oxidation tank. The ozone catalytic oxidation tank is provided with a catalyst, and the catalyst is a metal oxide catalyst or a supported catalyst with a metal oxide as an active component supported on an inert carrier.

7. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 1, characterized in that, The biological filtration unit comprises a multi-stage biological aerated filter and a backwashing effluent pipe connected with the multi-stage biological aerated filter, the multi-stage biological aerated filter is provided with a biological filter material layer, and the biological filter material layer comprises at least one of a volcanic rock layer, a ceramic layer, a quartz sand layer, an activated carbon layer and a zeolite layer; and the backwashing effluent pipe is used to output the sewage generated by cleaning the multi-stage biological aerated filter to the conditioning unit.

8. The coal-based solid waste innocenzation treatment wastewater treatment system according to claim 1, characterized in that, The clear water tank unit comprises a clear water tank, an external discharge pipeline, a reuse pipeline and a backwashing water pipeline connected with the clear water tank, the backwashing water pipeline is connected with the biological filtration unit and used to transport the filtered water stored in the clear water tank to the biological filtration unit to clean the biological filtration unit.

9. A treatment method of coal-based solid waste harmless disposal wastewater, applied to the coal-based solid waste harmless disposal wastewater treatment system of any one of claims 1-8, characterized in that, The method comprises: adjusting the water quality and water quantity of the input wastewater by the conditioning unit; coagulating, flocculating and precipitating the wastewater with adjusted water quality in sequence by the coagulation and sedimentation unit to remove sludge, suspended solids, colloidal particles and part of heavy metal pollutants, so as to obtain the wastewater after coagulation and sedimentation; performing ozone and hydrogen peroxide synergistic catalytic oxidation on the wastewater after coagulation and sedimentation by the ozone catalytic oxidation unit to remove refractory organic pollutants, so as to obtain the wastewater after ozone catalytic oxidation treatment; performing gravity sedimentation on the wastewater after ozone catalytic oxidation treatment by the gravity sedimentation unit to remove part of heavy metal pollutants and suspended solids, flocs and solid particles formed in the oxidation process, so as to obtain the wastewater after gravity sedimentation; performing biological degradation and filtration on the wastewater after gravity sedimentation by the biological filtration unit to remove biodegradable organic pollutants, part of suspended solids and part of inorganic pollutants, so as to obtain the filtered water, and collecting and storing the filtered water by the clear water tank unit.

10. The treatment method of coal-based solid waste innocenzation treatment wastewater according to claim 9, characterized by, The method further comprises: adjusting the volumes of the conditioning unit, the coagulation and sedimentation unit, the ozone catalytic oxidation unit, the gravity sedimentation unit and the biological filtration unit respectively to set the residence time of the wastewater in the conditioning unit, the coagulation and sedimentation unit, the ozone catalytic oxidation unit, the gravity sedimentation unit and the biological filtration unit.

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