Stearic acid PVC stabilizer production wastewater treatment system

Abstract

The utility model belongs to the technical field of wastewater treatment, and particularly relates to a stearate PVC stabilizer production wastewater treatment system. The production wastewater treatment system comprises a wastewater treatment system and a domestic sewage treatment system, the wastewater treatment system is used for treating wastewater containing cadmium, barium and zinc or wastewater containing lead; the wastewater treatment system comprises a wastewater grating, a wastewater adjusting tank, a low-temperature evaporation system, a temporary storage tank, a hydrolysis acidification tank, a hydrolysis sedimentation tank, an intermediate water tank, a UASB anaerobic reactor, an MBR bioreactor, a biological activated carbon adsorber and a clean water tank which are arranged in sequence; the domestic sewage treatment system comprises a sewage grating, a comprehensive wastewater adjusting tank, a biological treatment device and a comprehensive wastewater drainage tank which are arranged in sequence; sludge outlets of the hydrolysis sedimentation tank, the UASB anaerobic reactor, the MBR bioreactor and the biological treatment device are all connected to a sludge inlet of the sludge concentration tank; a sludge outlet of the sludge thickening tank is connected with a sludge dewatering machine.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater treatment, and particularly relates to a wastewater treatment system for the production of stearate PVC stabilizers. Background Art

[0002] Stearates (including lead stearate, cadmium stearate, zinc stearate, calcium stearate, barium stearate, etc.) are widely used as heat stabilizers for polyvinyl chloride plastics. Most of the production is obtained by directly reacting stearic acid with a certain metal salt (such as tribasic lead sulfate, cadmium chloride, calcium chloride, zinc sulfate, barium chloride, etc.) under hot alkaline conditions. Therefore, in addition to a certain amount of organic matter, the stearate wastewater also contains a certain concentration of harmful heavy metals such as Pb, Cd, and Zn.

[0003] The PVC composite stabilizer products cover the whole country. For various PVC stabilizers (stearates), the product structure is mainly the LF-S5001 series composite stabilizer, which is widely used in the production and manufacturing of PVC plastic-steel profiles. This stabilizer is also widely used in products such as PVC plastic pipes, PVC films, artificial leather, light box advertising films, and PVC cable materials. During the production process of this product, mainly cadmium-containing wastewater, lead-containing wastewater, and comprehensive domestic wastewater (such as canteens, toilets, etc.) are discharged.

[0004] Table 1 Water quality of main wastewater (pH is dimensionless, other units are mg / L)

[0005]

[0006] Table 2 The effluent water quality meets the first-class standard of the Comprehensive Wastewater Discharge Standard (GB8978-1996) (pH is dimensionless, other units are mg / L)

[0007] Emission standards PH Total cadmium (mg / L) Total lead (mg / L) Total zinc (mg / L) COD (mg / L) Production wastewater 6-9 0.1 1.0 2.0 100 Content of the Utility Model

[0008] The utility model adopts a process of filtration + evaporation + biochemical treatment (hydrolysis + anaerobic + aerobic) + activated carbon adsorption to remove heavy metals, salts, and organic matter in the zinc-containing wastewater, lead-containing wastewater, and the collected initial rainwater discharged during the production process, and adopts a process of filtration + biological treatment to purify domestic sewage, providing a method for treating stearate wastewater.

[0009] In order to solve the above existing technical problems, the present application provides the following technical solutions:

[0010] The utility model provides a wastewater treatment system for the production of stearic acid PVC (polyvinyl chloride) stabilizers, including a wastewater treatment system and a domestic sewage treatment system; the wastewater treatment system is used for the treatment of cadmium, barium, zinc-containing wastewater or lead-containing wastewater.

[0011] The wastewater treatment system includes a wastewater grille, a wastewater equalization tank, a low-temperature evaporation system, a storage tank, a hydrolysis acidification tank, a hydrolysis sedimentation tank, an intermediate water tank, a UASB (Upflow Anaerobic Sludge Bed) anaerobic reactor, an MBR (Membrane Bioreactor) bioreactor, a biological activated carbon adsorber, and a clear water tank, which are arranged in sequence;

[0012] The domestic sewage treatment system includes a sewage grille, a comprehensive wastewater equalization tank, a biological treatment device, and a comprehensive wastewater drainage tank, which are arranged in sequence;

[0013] The sludge outlets of the hydrolysis sedimentation tank, the UASB anaerobic reactor, the MBR bioreactor, and the biological treatment device are all connected to the sludge inlet of the sludge thickening tank; the sludge outlet of the sludge thickening tank is connected with a sludge dewatering machine.

[0014] Preferably, the wastewater grille is a mechanical grille

[0015] Preferably, an aeration and agitation device is provided in the wastewater equalization tank.

[0016] Preferably, the hydrolysis acidification tank is selected from a completely mixed hydrolysis acidification tank, and a submersible agitator is provided inside.

[0017] Preferably, the hydrolysis sedimentation tank is a vertical sedimentation tank.

[0018] Preferably, a circulation pump is provided inside the UASB anaerobic reactor.

[0019] Preferably, in the MBR bioreactor, the aerator is a disc-type bottom aerator and is connected with a blower.

[0020] Preferably, the MBR bioreactor is an integrated bioreactor, its membrane module is directly immersed in the aeration tank, and a self-priming pump is used to suction and filter the effluent.

[0021] Preferably, the biological treatment device is selected from a biological membrane reactor, and a biological membrane is provided inside; the biological membrane is a fixed filler on which microorganisms can attach and grow.

[0022] Preferably, the sludge dewatering machine is selected from a spiral sludge dewatering machine.

[0023] Preferably, the outlets of the clear water tank and the comprehensive wastewater drainage tank are both connected to the drainage outlet.

[0024] Furthermore, the wastewater treatment method of the stearate PVC stabilizer production wastewater treatment system includes the following steps:

[0025] Cadmium-containing barium-zinc wastewater (hereinafter collectively referred to as cadmium-containing wastewater), lead-containing wastewater treatment system:

[0026] S1: The cadmium-containing wastewater and lead-containing wastewater are respectively mixed with the initial rainwater in the grid well, and after removing large particulate suspended solids through the grid respectively, they flow into each regulating tank for separate collection by gravity.

[0027] S2: The cadmium wastewater (containing rainwater) and lead wastewater (containing rainwater) are respectively pumped to the evaporation system. Salts, heavy metals, high-boiling-point organic substances, etc. gradually form concentrated liquid as the solvent decreases during the evaporation process. The formed concentrated liquid is entrusted for off-site treatment. The evaporated water, low-boiling-point and volatile substances form condensate after cooling. The two evaporation condensates are merged and enter the temporary storage tank.

[0028] S3: The wastewater in the temporary storage tank is pumped to the hydrolysis acidification tank to decompose macromolecular organic substances and convert them into soluble and easily degradable small molecules, while removing part of the COD (chemical oxygen demand) and improving the biodegradability of the water quality.

[0029] S4: In the vertical flow sedimentation tank, the effluent from the hydrolysis acidification tank is separated into mud and water, and the supernatant flows into the intermediate water tank.

[0030] S5: The water in the intermediate water tank is pumped to the UASB anaerobic reactor to convert a large amount of organic substances into biogas for removal.

[0031] S6: MBR membrane bioreactor: The effluent from the anaerobic reactor is mixed with the activated sludge (microbial flocs) containing a large number of aerobic microorganisms. Under the aeration condition, through the metabolic action of microorganisms, the organic substances in the sewage are oxidized and decomposed into inorganic substances. The filtration function of the membrane module immersed in the biological reaction tank can intercept the activated sludge and macromolecular organic substances in the biochemical reaction tank. Water and small molecules pass through the membrane surface and are pumped out by the self-priming pump, thus realizing the separation of mud and water.

[0032] S7: The effluent from the MBR reactor enters the biological activated carbon adsorption unit for the adsorption of heavy metals and the adsorption and degradation of organic substances.

[0033] Domestic wastewater treatment:

[0034] S8: Domestic sewage flows into the regulating tank for separate collection by gravity after removing large particulate suspended solids through the grid.

[0035] S9: The domestic sewage in the regulating tank is pumped to the biochemical treatment device to degrade organic substances and then flows into the discharge water tank for up-to-standard discharge by gravity.

[0036] Sludge treatment:

[0037] S10: The sludge of this process mainly comes from the surplus sludge of biological reactors such as MBR. A sludge thickening tank is set up to collect and thicken the sludge, and corresponding sludge dewatering equipment is set up for sludge dewatering. The filtrate of the sludge treatment system is recycled for treatment.

[0038] Specific description:

[0039] Treatment system for cadmium-containing wastewater and lead-containing wastewater:

[0040] In the treatment system for cadmium-containing wastewater and lead-containing wastewater, the cadmium-containing wastewater and lead-containing wastewater are respectively pumped to a low-temperature multi-effect evaporation system. During the evaporation process, as the solvent decreases, salts, heavy metals, high-boiling organic substances, etc. gradually form a concentrated liquid, which is sent out for external treatment. The evaporated water, low-boiling and volatile substances are cooled to form condensate. After the condensate passes through the biochemical system and the biological activated carbon system to adsorb heavy metals and degrade organic substances, it is discharged up to standard.

[0041] Low-temperature evaporation: It refers to a process in which components in a liquid are evaporated through specific technological means in a low-temperature environment, thereby achieving the separation, purification or concentration of substances. This process can be subdivided into low-temperature vacuum evaporation and low-temperature atmospheric evaporation. In this system, a low-temperature vacuum evaporation device is selected. By reducing the system pressure, that is, reducing the saturated vapor pressure of the components, the evaporation rate of water or some volatile substances can be increased at a lower temperature, and it has the advantage of lower operating energy consumption.

[0042] Multi-effect evaporation: Heating steam is introduced into the first-effect evaporator. The solution is heated and evaporated to generate secondary steam, which is then introduced into the second-effect evaporator as a heating heat source, and so on. Multiple evaporators can be connected in series to form multi-effect evaporation. Since the evaporation temperature and pressure of the subsequent effect are lower than those of the previous effect, the boiling point of the solution in each effect also decreases in turn. In this way, heat energy can be transferred and utilized between multiple evaporators, thereby improving the overall thermal efficiency.

[0043] The biochemical system adopts an advanced and mature biological treatment process of hydrolysis acidification + UASB + MBR to biodegrade all organic substances in the wastewater. The process has stable operation, compact structure, good effect, saves investment in land, and has low operating costs.

[0044] The biological activated carbon adsorber is a wastewater treatment device that combines biological degradation and activated carbon adsorption technologies, and has the functions of degrading organic substances and adsorbing heavy metal substances. Specifically as follows:

[0045] ① Activated carbon adsorption: As the core part of the adsorption tower, activated carbon has a very high specific surface area and porosity, and can effectively adsorb organic pollutants, heavy metal ions, etc. in the wastewater. The adsorption of activated carbon is mainly physical adsorption, that is, pollutants are adsorbed on the surface of activated carbon through intermolecular forces.

[0046] ②Biodegradation: On the surface of the activated carbon, there is a layer of microbial community attached. These microorganisms can use the pollutants adsorbed by the activated carbon as a nutrient source for growth and reproduction, and convert the pollutants into harmless or low-toxic substances through biodegradation. This biodegradation enhances the treatment capacity of the activated carbon adsorption tower, enabling it to treat more complex pollutants.

[0047] ③Synergistic effect: The adsorption of activated carbon and the biodegradation of microorganisms promote each other in the biological activated carbon adsorber. The adsorption of pollutants by activated carbon provides a rich nutrient source for microorganisms, while the biodegradation of microorganisms reduces the adsorption burden of activated carbon and extends its service life.

[0048] Specifically, in step S1, the cadmium-containing wastewater and lead-containing wastewater are respectively mixed with the initial rainwater in the grid well, and after removing large particulate suspended solids through the grid, they flow into each regulating tank separately for collection.

[0049] Preferably, in step S1, the grid is mechanical, which has the advantages of simple operation, small workload, and labor cost savings compared with manual grids. The grid residues are outsourced for treatment.

[0050] Preferably, in step S1, there is an aeration and stirring device in the regulating tanks for cadmium-containing wastewater and lead-containing wastewater, and the aeration intensity is 1 - 3 m 3 / (m 2 ·h).

[0051] Specifically, in step S2, the cadmium-containing wastewater (including rainwater) and lead-containing wastewater (including rainwater) are respectively pumped to the low-temperature multi-effect evaporation system. The salts, heavy metals, and high-boiling organic substances therein gradually form a concentrated solution as the solvent decreases during the evaporation process. The formed concentrated solution is outsourced for treatment. The evaporated water, low-boiling and volatile substances are cooled after heat exchange to form condensate. The evaporation condensates of cadmium-containing wastewater and lead-containing wastewater are combined and enter the temporary storage tank.

[0052] Specifically, in step S2, due to the large differences in material properties such as the treatment water volume and organic matter content between the lead-containing wastewater and cadmium-containing wastewater, the operating parameters such as pressure, temperature, and evaporation effect number at the optimal evaporation effect may be different. Therefore, evaporation devices are respectively set for evaporation treatment to reduce the operation difficulty of evaporation operation and make the process operation optimal at the same time.

[0053] Specifically, in step S2, the evaporation processes of cadmium-containing wastewater and lead-containing wastewater both adopt the low-temperature multi-effect vacuum evaporation process, and the separation process of each component is completed under the low-temperature condition of not exceeding 70°C. The multi-effect series process recycles the secondary steam, achieving higher efficiency while saving energy.

[0054] Preferably, in step S2, the number of effects of the evaporation system is selected to be 2 - 3 effects. The reasons are as follows:

[0055] I. Advantages of increasing the number of effects

[0056] Improved thermal efficiency: As the number of effects increases, the amount of water evaporated from the solution per kilogram of fresh steam (i.e., the evaporation ratio) increases, and the thermal efficiency is correspondingly improved. Theoretically, more effects can make more full use of the latent heat of steam and reduce heat loss.

[0057] Reduced steam consumption: The transition from a single - effect to a multi - effect can significantly reduce the consumption of heating steam. For example, when changing from a single - effect to a double - effect, about 50% of the heating steam can be saved; however, as the number of effects further increases, the amount of saved steam gradually decreases. For example, when changing from a four - effect to a five - effect, only about 10% of the heating steam is saved.

[0058] II. Disadvantages of increasing the number of effects

[0059] Increased heat transfer temperature difference loss: As the number of effects increases, the heat transfer temperature difference loss also increases, which may lead to a decrease in the production intensity of the evaporator, that is, the amount of water evaporated per unit time decreases.

[0060] Increased equipment cost: Increasing the number of effects means more evaporators and other auxiliary equipment are needed, which will cause the equipment cost to increase exponentially.

[0061] Increased operation complexity: The operation and control of a multi - effect evaporation system are relatively complex and require a higher technical level and more refined operation management.

[0062] III. Basis for selecting the number of effects

[0063] Material properties: The properties of the material (such as viscosity, boiling point, thermal sensitivity, etc.) are important factors affecting the selection of the number of effects. For heat - sensitive materials, the number of effects should be minimized to reduce the heating temperature; for high - viscosity materials, more effects may be needed to improve the heat transfer effect.

[0064] Throughput: Materials with a large throughput are suitable for multi - effect evaporation to save steam consumption; while materials with a small throughput may not require too many effects to meet the requirements.

[0065] Economic benefits: When selecting the number of effects, it is necessary to comprehensively consider the equipment cost and operation cost. Generally speaking, as the number of effects increases, the saved steam cost will gradually decrease, while the equipment cost will increase significantly. Therefore, a balance point needs to be found to minimize the total cost.

[0066] Specifically, in step S3, the wastewater in the temporary storage pool is pumped to the hydrolysis acidification pool to decompose macromolecular organic substances and convert them into soluble and easily degradable small molecules, while removing part of the COD and improving the biodegradability of the wastewater.

[0067] Preferably, in step S3, the hydrolysis acidification tank is a completely mixed hydrolysis acidification tank, equipped with a submersible agitator with a power of 10-25 (W / m 3 tank body). There is no need to set a water distributor for the influent, and the treatment effect is better.

[0068] Preferably, in step S3, the dissolved oxygen in the hydrolysis acidification tank < 0.3mg / L.

[0069] Specifically, in step S4, in the vertical flow sedimentation tank, the effluent from the hydrolysis acidification tank is separated into mud and water, and the supernatant flows into the intermediate water tank.

[0070] Preferably, in step S4, the hydrolysis sedimentation tank is vertical flow type. For urban areas with tight land resources, its advantage of small floor area is particularly important. Its large depth and special tank body structure enable a good sedimentation effect without setting a sludge scraper, reducing the power cost and making management more convenient.

[0071] Preferably, in step S4, the surface loading of the vertical flow sedimentation tank is 0.5-1.5m 3 / m 2 ·h.

[0072] Specifically, in step S5, a circulation pump is set in the reactor, which operates intermittently to prevent the height of the sludge layer in the reactor from being insufficient due to insufficient upward flow velocity and sludge sedimentation, greatly shortening the contact time between the sludge and water, and thus affecting the treatment effect.

[0073] Preferably, in step S5, most of the organic matter is removed in the UASB reactor, and the anaerobic operation is at a medium temperature of 33°C. The condensate still has residual heat after evaporation, and there is no need to heat the influent again, saving energy.

[0074] Specifically, in step S6, the effluent from the anaerobic reactor is mixed with the activated sludge (microbial flocs) containing a large amount of aerobic microorganisms. Under the aeration condition, through the metabolic action of the microorganisms, the organic substances in the sewage are oxidized and decomposed into inorganic substances. The filtration function of the membrane module immersed in the biological reaction tank can intercept the activated sludge and macromolecular organic matter in the biochemical reaction tank, and the water and small molecules pass through the membrane surface and are pumped out by the self-priming pump, thus realizing the separation of mud and water.

[0075] Specifically, in step S6, the MBR tank is also equipped with a sludge return system, which is connected to the UASB anaerobic reactor, the hydrolysis acidification tank, and the domestic sewage purification device to supplement the biomass of each biochemical system.

[0076] Preferably, in step S6, the aerator is a disc-type bottom aerator, which is connected to the blower and has the advantages of convenient installation, good oxygenation effect, and low failure rate.

[0077] Preferably, in step S6, the MBR bioreactor is an integrated type, the membrane assembly is directly immersed in the aeration tank, and the filtered water is sucked by a self-priming pump. Compared with the traditional aeration tank and split-type MBR device, it has a higher sludge concentration and processing load, does not need to set up a secondary sedimentation tank, saves more land and saves more investment.

[0078] Preferably, in step S6, the dissolved oxygen in the MBR pool is 2.5 mg / L.

[0079] Specifically, in step S7, the effluent from the MBR reactor enters the biological activated carbon adsorption unit to complete the adsorption of heavy metals and the adsorption and degradation of organic matter.

[0080] Preferably, in step S7, the activated carbon is preferably coconut shell activated carbon. Coconut shell activated carbon is made from coconut shell, has a microporous structure and a large specific surface area, has a strong adsorption capacity and good chemical stability.

[0081] It has a good adsorption effect on heavy metal ions such as lead, zinc, cadmium, etc.

[0082] Preferably, in step S7, the mesh size of coconut shell activated carbon is preferably 15 to 30 meshes, to avoid selecting a mesh size that is too small, resulting in insufficient adsorption capacity and poor filtration effect, and a mesh size that is too large, resulting in greater resistance when water flows through, and easy clogging, making regeneration difficult.

[0083] Domestic wastewater treatment:

[0084] Specifically, in step S8, the domestic sewage passes through a screen to remove large suspended solids and then flows into a regulating tank for separate collection.

[0085] Preferably, in step S8, a mechanical grid is set for domestic sewage to filter and intercept large suspended solid particles and floating objects, thereby reducing the burden on subsequent treatment devices. Aeration stirring is provided in the domestic sewage regulating tank, and the aeration intensity is (1-3m 3 / m 2 h).

[0086] Specifically, in step S9, the domestic sewage in the regulating tank is pumped to the biochemical treatment device to degrade organic matter and then flows into the discharge pool to meet the discharge standards.

[0087] Preferably, in step S9, the biological treatment device is a biofilm reactor, in which fixed soft and semi-soft composite fillers on which microorganisms can attach and grow are arranged to form a biofilm. The sewage enters from the water distributor at the bottom of the reactor and flows from bottom to top through the biofilm on the filler layer. Organic matter is adsorbed by the filler and the biofilm and finally degraded by microorganisms, and the effluent is purified.

[0088] Sludge treatment:

[0089] Specifically, in step S10, a sludge thickening tank is set up to collect and thicken the surplus biological sludge in the MBR tank, etc., and corresponding sludge dewatering equipment is set up for sludge dewatering. The filtrate of the sludge treatment system is recycled and treated.

[0090] The technical solution of the present utility model has the following advantages compared with the prior art:

[0091] A production wastewater treatment system for stearate PVC stabilizers provided by the present utility model. This type of wastewater is characterized by high salt content, heavy metal pollution, high organic matter concentration, etc. The wastewater treatment system uses a low-temperature multi-effect evaporation system and an activated carbon adsorption system to effectively separate salts and heavy metals, and a complete biochemical system of hydrolysis acidification + anaerobic + aerobic is used to degrade organic matter to complete the purification of polluted wastewater. Description of the Drawings

[0092] Figure 1 It is a structural diagram of the production wastewater treatment system for stearate PVC stabilizers of the present utility model.

[0093] Figure 2 It is a process schematic diagram of the production wastewater treatment system for stearate PVC stabilizers of the present utility model.

[0094] Description of the reference numerals: 1 - wastewater grille, 2 - wastewater regulation tank, 3 - low-temperature evaporation system, 4 - temporary storage tank, 5 - hydrolysis acidification tank, 6 - hydrolysis sedimentation tank, 7 - intermediate water tank, 8 - UASB anaerobic reactor, 9 - MBR bioreactor, 10 - biological activated carbon adsorber, 11 - clean water tank, 12 - sludge thickening tank, 13 - sludge dewatering machine, 14 - sewage grille, 15 - comprehensive wastewater regulation tank, 16 - biological treatment device, 17 - comprehensive wastewater drainage tank, 18 - drain outlet. Specific Embodiments

[0095] The present utility model will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present utility model and be able to implement it, but the embodiments cited do not limit the present utility model.

[0096] Embodiment 1

[0097] A production wastewater treatment system for stearic acid PVC stabilizers includes a wastewater treatment system and a domestic sewage treatment system; the wastewater treatment system is used for the treatment of cadmium-barium-zinc-containing wastewater or lead-containing wastewater;

[0098] The wastewater treatment system includes a wastewater grille 1, a wastewater regulation tank 2, a low-temperature evaporation system 3, a temporary storage tank 4, a hydrolysis acidification tank 5, a hydrolysis sedimentation tank 6, an intermediate water tank 7, a UASB anaerobic reactor 8, an MBR bioreactor 9, a biological activated carbon adsorber 10, and a clean water tank 11 arranged in sequence;

[0099] The wastewater grille 1 is a mechanical grille, and an aeration and agitation device is provided in the wastewater regulation tank 2. The hydrolysis acidification tank 5 is selected from a completely mixed hydrolysis acidification tank, and a submersible agitator is provided inside. The hydrolysis sedimentation tank 6 is a vertical sedimentation tank. A circulation pump is provided inside the UASB anaerobic reactor 8.

[0100] In the MBR bioreactor 9, the aerator is a disc bottom aerator and is connected to a blower. The MBR bioreactor 9 is an integrated bioreactor, and its membrane module is directly immersed in the aeration tank, and a self-priming pump is used to suck and filter the effluent.

[0101] The domestic sewage treatment system includes a sewage grille 14, a comprehensive wastewater regulation tank 15, a biological treatment device 16, and a comprehensive wastewater drainage tank 17 arranged in sequence;

[0102] The sludge outlets of the hydrolysis sedimentation tank 6, the UASB anaerobic reactor 8, the MBR bioreactor 9, and the biological treatment device 16 are all connected to the sludge inlet of the sludge thickening tank 12; the sludge outlet of the sludge thickening tank 12 is connected to a sludge dewatering machine 13.

[0103] The biological treatment device 16 is selected from a biological membrane reactor, and a biological membrane is provided inside; the biological membrane is a fixed filler on which microorganisms can attach and grow. The sludge dewatering machine 13 is selected from a spiral sludge dewatering machine.

[0104] Example 2 Cadmium-containing wastewater and lead-containing wastewater treatment system

[0105] The cadmium-containing wastewater and the lead-containing wastewater are respectively mixed with the initial rainwater in the grille well, and after removing large particle suspended solids through a mechanical grille respectively, they flow into each regulation tank separately for collection, and the grid residues are disposed of externally.

[0106] An aeration and agitation device is provided in the cadmium-containing wastewater and lead-containing wastewater regulation tanks, and the aeration intensity is 1.5 m 3 / (m 2 ·h).

[0107] The cadmium-containing wastewater (containing rainwater) and the lead-containing wastewater (containing rainwater) are respectively pumped to a low-temperature multi-effect evaporation system. The salts, heavy metals, and high-boiling-point organic substances therein gradually form a concentrated liquid with the reduction of the solvent during the evaporation process. The formed concentrated liquid is disposed of externally. The evaporated water, low-boiling-point, and volatile substances are formed into condensate after heat exchange and cooling. The evaporation condensates of the cadmium-containing wastewater and the lead-containing wastewater are merged into the temporary storage tank. The separation efficiency of salts and heavy metals in this process reaches more than 97%.

[0108] The number of effects for multi-effect evaporation of cadmium-containing wastewater is 3 effects, and that of lead-containing wastewater is 2 effects.

[0109] The wastewater in the temporary storage tank is pumped to a completely mixed hydrolysis acidification tank to decompose macromolecular organic substances and convert them into soluble and easily degradable small molecules, improving the biodegradability of the wastewater while removing part of the COD.

[0110] The power of the submersible agitator in the hydrolysis acidification tank is 20 (W / m 3 tank body), and the dissolved oxygen is <0.5 mg / L.

[0111] The effluent from the hydrolysis acidification tank enters a vertical flow sedimentation tank for sediment-water separation, and the supernatant flows into the intermediate water tank. The surface load of the vertical flow sedimentation tank is 0.7 m 3 / m 2 ·h.

[0112] The water in the intermediate water tank is pumped to a UASB anaerobic reactor to convert a large amount of organic substances into biogas for removal. The reactor is equipped with a circulation pump and operates intermittently to prevent the sludge layer height in the reactor from being insufficient due to insufficient upward flow velocity and sludge sedimentation, resulting in a greatly shortened contact time between sludge and water, thereby affecting the treatment effect.

[0113] The UASB reactor operates at a medium temperature of 33 °C for anaerobic treatment. The condensate after evaporation still has residual heat, and there is no need to heat the influent again.

[0114] The effluent from the anaerobic reactor is mixed with activated sludge (microbial flocs) containing a large number of aerobic microorganisms. Under aeration conditions, through the metabolic action of microorganisms, the organic substances in the sewage are oxidized and decomposed into inorganic substances. The filtration function of the membrane module immersed in the biological reaction tank can intercept the activated sludge and macromolecular organic substances in the biochemical reaction tank, and water and small molecules pass through the membrane surface and are pumped out by a self-priming pump, thus realizing sediment-water separation. The MBR tank is equipped with a sludge reflux system, which is connected to the UASB anaerobic reactor, the hydrolysis acidification tank, and the domestic sewage purification device to supplement the biomass of each biochemical system.

[0115] The aerator in the MBR tank is a disc-type bottom aerator, which is connected to a blower.

[0116] The MBR bioreactor is integrated, and the membrane module is directly immersed in the aeration tank, and the filtered water is pumped by a self-priming pump.

[0117] The dissolved oxygen in the MBR tank is 2.5 mg / L.

[0118] The effluent from the MBR reactor enters the biological activated carbon adsorption unit to complete the adsorption of heavy metals and the adsorption and degradation of organic substances.

[0119] The activated carbon for adsorption is coconut shell activated carbon, which has good adsorption effect on heavy metal ions such as lead, zinc, cadmium, etc.

[0120] The mesh number of the coconut shell activated carbon is 20 mesh. Avoid choosing too small mesh number, which may lead to insufficient adsorption capacity and poor filtration effect. Too large mesh number will cause greater resistance when water flows through, and it is easy to be blocked and difficult to regenerate.

[0121] Example 3 Domestic Sewage Treatment

[0122] After the domestic sewage removes large particle suspended solids through the grille, it flows into the regulating tank by gravity for separate collection, reducing the burden on the subsequent treatment device.

[0123] There is aeration and agitation in the domestic sewage regulating tank, and the aeration intensity is 1.5m 3 / m 2 ·h.

[0124] The domestic sewage in the regulating tank is pumped to the biochemical treatment device to degrade organic matters, and then flows into the discharge tank by gravity for up-to-standard discharge. The biological treatment device is a biological membrane reactor. Fixed soft and semi-soft combined fillers for the attachment and growth of microorganisms are set in the reactor to form a biological membrane. The sewage enters from the bottom water distributor of the reactor and flows through the biological membrane on the filler layer from bottom to top. The organic matters are adsorbed by the filler and the biological membrane and finally degraded by microorganisms, and the effluent is purified.

[0125] Example 4 Sludge Treatment

[0126] A sludge thickening tank is set to collect and thicken the excess biological sludge such as in the MBR tank, and corresponding sludge dewatering equipment is set for sludge dewatering. The filtrate of the sludge treatment system is recycled for treatment, and the sludge cake is sent out for off-site treatment.

[0127] The sludge dewatering equipment is a spiral sludge dewatering machine.

[0128] In the wastewater treatment system, the cadmium-containing wastewater grille well and the lead-containing wastewater grille well are respectively connected to the cadmium-containing wastewater regulating tank and the lead-containing wastewater regulating tank; the outlets of the lift pumps of the cadmium-containing wastewater regulating tank and the lead-containing wastewater regulating tank are respectively connected to the inlets of the cadmium-containing wastewater evaporation system and the lead-containing wastewater evaporation system; both the cadmium-containing wastewater evaporation system and the lead-containing wastewater evaporation system are connected to the storage tank; the outlet of the lift pump of the storage tank is connected to the inlet of the hydrolysis acidification tank; the hydrolysis acidification tank is connected to the hydrolysis sedimentation tank; the hydrolysis sedimentation tank is connected to the intermediate water tank; the outlet of the lift pump of the intermediate water tank is connected to the inlet of the UASB reactor; the UASB reactor is connected to the MBR reactor; the outlet of the self-priming pump of the MBR reactor is connected to the inlet of the biological activated carbon system; the biological activated carbon system is connected to the discharge tank.

[0129] In the wastewater treatment system, the domestic sewage grille well is connected to the domestic sewage regulating tank; the lift pump of the domestic sewage regulating tank is connected to the inlet of the domestic sewage biochemical treatment device; the domestic sewage biochemical treatment device is connected to the discharge tank.

[0130] The UASB reactor is equipped with an internal circulation pump and pipelines; the MBR reactor is equipped with a sludge return pump and pipelines, and the pipelines are respectively connected to the UASB reactor, the hydrolysis acidification tank, and the domestic sewage biochemical treatment device.

[0131] The sludge treatment system includes: the outlet of the sludge pump of the hydrolysis sedimentation tank is connected to the inlet of the sludge thickening tank; the sludge discharge port of the UASB reactor is connected to the inlet of the sludge thickening tank (gravity sludge discharge); the outlet of the sludge pump of the MBR reactor is connected to the inlet of the sludge thickening tank.

[0132] The present utility model has no special limitations on the shape, size, etc. of each treatment facility of the production wastewater treatment system for stearate PVC stabilizers. It is only necessary to ensure the smooth progress of the corresponding treatment process according to the treatment water volume.

[0133] Effect evaluation 1

[0134] Table 3 Wastewater treatment of each treatment unit

[0135]

[0136] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present utility model.

Claims

1. A stearic acid PVC stabilizer production wastewater treatment system, characterized in that: It includes a wastewater treatment system and a domestic sewage treatment system; the wastewater treatment system is used for treating wastewater containing cadmium, barium and zinc or wastewater containing lead; The wastewater treatment system comprises a wastewater grid (1), a wastewater regulating tank (2), a low-temperature evaporation system (3), a temporary storage tank (4), a hydrolysis acidification tank (5), a hydrolysis sedimentation tank (6), an intermediate water tank (7), a UASB anaerobic reactor (8), an MBR bioreactor (9), a biological activated carbon adsorber (10) and a clear water tank (11) which are arranged in sequence; The domestic sewage treatment system comprises a sewage grille (14), a comprehensive wastewater regulating tank (15), a biological treatment device (16) and a comprehensive wastewater drainage tank (17) which are arranged in sequence; The mud outlets of the hydrolysis sedimentation tank (6), the UASB anaerobic reactor (8), the MBR bioreactor (9) and the biological treatment device (16) are all connected to the mud inlet of the sludge thickening tank (12); the mud outlet of the sludge thickening tank (12) is connected to a sludge dewatering machine (13).

2. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The wastewater screen (1) is a mechanical screen.

3. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The wastewater regulating tank (2) is provided with an aeration and stirring device.

4. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The hydrolysis acidification tank (5) is selected from a completely mixed hydrolysis acidification tank, and a submersible agitator is provided inside.

5. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The hydrolysis sedimentation tank (6) is a vertical flow sedimentation tank.

6. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: A circulation pump is provided inside the UASB anaerobic reactor (8).

7. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: In the MBR bioreactor (9), the aerator is a disc-type bottom aerator and is connected to a blower.

8. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The MBR bioreactor (9) is an integrated bioreactor, the membrane components of which are directly immersed in the aeration tank, and a self-priming pump is used to suck and filter out water.

9. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The biological treatment device (16) is selected from a biofilm reactor, and a biofilm is arranged inside; the biofilm is a fixed filler on which microorganisms can attach and grow.

10. The stearic acid PVC stabilizer production wastewater treatment system as claimed in claim 1, characterized in that: The sludge dewatering machine (13) is selected from a screw stack type sludge dewatering machine.

Images