Centralized wastewater treatment device and method for food park

Abstract

The invention discloses a centralized wastewater treatment device and method for a food park, and the method comprises the following steps: low-concentration wastewater passes through a first grid and then enters a comprehensive oil removal adjusting tank, and high-concentration wastewater passes through a second grid and a high-concentration oil removal adjusting tank in sequence and then is pumped into the comprehensive oil removal adjusting tank; effluent of the comprehensive oil separation regulating tank sequentially passes through an air floatation tank, a primary sedimentation tank, an internal circulation anaerobic reactor, an A / O tank, a secondary sedimentation tank and a magnetic coagulation sedimentation tank, and is discharged after reaching the standard. According to the invention, the food park enterprise wastewater is collected for centralized treatment, through physicochemical pretreatment of the front-end air floatation tank and the primary sedimentation tank, biochemical treatment of the middle-end internal circulation anaerobic reactor and the A / O tank, and deep physicochemical treatment of the tail-end magnetic coagulation sedimentation, insoluble reducing substances, SS, chromaticity, total nitrogen and total phosphorus in the wastewater are effectively reduced, the treatment effect is good, and the efficiency is low; meanwhile, the biochemical treatment process combines internal circulation and external circulation, so that self-digestion of the sludge is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a centralized wastewater treatment device and method for a food park. Background Art

[0002] In response to the water pollution problem, the wastewater treatment of enterprises in the park has caused inconvenience to the production and development of enterprises, and it occupies a large area and consumes a lot of energy, which restricts the sustainable social and economic development of the food park. Therefore, centralized wastewater treatment for food parks is of great significance.

[0003] Common methods for food wastewater treatment include physical methods, chemical methods and biological methods. Physical methods mainly include precipitation, filtration, evaporation, etc. By adding substances such as precipitants, filters and evaporators, pollutants in food wastewater are separated and removed to achieve the treatment effect. This method is simple and easy to implement, but the treatment efficiency is relatively low. Chemical methods mainly use the principle of chemical reaction to decompose or transform pollutants using chemical agents. Common chemical methods include oxidation, reduction, neutralization, etc. Although the effect is good, some agents are also polluting and may produce new pollutants after treatment. Biological methods use microorganisms to degrade organic pollutants in wastewater, usually using biological treatment equipment such as aerobic tanks, anaerobic tanks and biological filters. Biological treatment methods have good treatment effects and low costs, but require certain technology and experience and are difficult to control.

[0004] In summary, it is of great significance to develop a centralized wastewater treatment device and method for food parks with good treatment effect and high efficiency to reduce wastewater generation and effectively treat it. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a centralized wastewater treatment device and method for a food park, which directly collects wastewater from enterprises that has not been pretreated and classifies it into high-concentration wastewater and low-concentration wastewater. After being treated by the wastewater treatment device, the wastewater meets the discharge standards, and the effluent meets the first-level discharge standard in the "Comprehensive Sewage Discharge Standard" (GB 8978-1996), thereby solving the problem of difficult wastewater treatment in park enterprises.

[0006] In order to solve the above technical problems, the present invention provides a method for treating centralized wastewater in a food park, comprising the following steps:

[0007] S1. Collect enterprise wastewater and classify it into high-concentration wastewater and low-concentration wastewater. The low-concentration wastewater enters the comprehensive oil separation regulating tank after passing through the first grid, and the high-concentration wastewater is pumped into the comprehensive oil separation regulating tank after passing through the second grid and the high-concentration oil separation regulating tank in sequence;

[0008] S2, the effluent from the comprehensive oil separation regulating tank enters the flotation tank, a demulsifier is added and compressed air is introduced into the wastewater, so that the emulsified oil and suspended particles in the wastewater form foam and float up and separate;

[0009] S3, the effluent from the flotation tank flows into the primary sedimentation tank by gravity, and polyferric sulfate (PFS) and polyacrylamide (PAM) are added to adsorb suspended matter and total phosphorus and capture them by precipitation net;

[0010] S4, the effluent from the primary sedimentation tank enters the internal circulation anaerobic reactor after temperature control in the biochemical water distribution tank, and the organic matter is decomposed, metabolized and digested by anaerobic bacteria; a three-phase separator is arranged in the internal circulation anaerobic reactor to effectively separate the gas generated from the sludge bed, and the reactor forms sludge flocs with good settling performance, and a sludge sedimentation system is arranged in the reactor to separate the gas, liquid and solid phases;

[0011] S5. The effluent of the internal circulation anaerobic reactor flows into the A / O tank by gravity to remove TN, NH3-N and organic matter. In view of the high C / N ratio in wastewater from food enterprises, no carbon source is added for denitrification treatment, which saves costs. The aerobic tank is set after the anoxic tank to further remove the residual organic matter from denitrification and improve the effluent quality. The anoxic tank acts as a biological selector, which is conducive to controlling sludge swelling. The alkalinity generated by denitrification can supplement the alkalinity consumed by the nitrification process. The system has a small amount of residual sludge.

[0012] S6. The effluent from the A / O tank enters the secondary sedimentation tank to separate mud and water; the secondary sedimentation tank adopts radial flow type, which is simple to operate, reliable in operation, and completely discharges mud; part of the sludge is returned to the A / O aerobic tank, and part is returned to the anaerobic tank for further anaerobic digestion, so as to achieve the purpose of sludge reduction;

[0013] S7, the effluent from the secondary sedimentation tank flows into the magnetic coagulation sedimentation tank by gravity, and polyferric sulfate, alkali, polyacrylamide and magnetic powder are added to further remove total phosphorus, suspended matter and organic matter;

[0014] S8. The effluent from the magnetic coagulation sedimentation tank meets the discharge standards.

[0015] Furthermore, the retention time of the comprehensive oil separation regulating tank and the high-concentration oil separation regulating tank is 8-10 hours; the retention time of the biochemical water distribution tank is 2-5 hours.

[0016] The biochemical section of the present invention adopts an internal circulation anaerobic reactor + A / O + secondary sedimentation tank phosphorus and nitrogen removal process, and adopts two modes of internal circulation and external circulation to simultaneously remove total nitrogen and total phosphorus. The internal circulation is that the nitrification liquid of the internal circulation anaerobic reactor and the aerobic tank of A / O is returned to the anoxic tank, and the nitrification liquid return amount is 1.5 to 2.5 times the water inlet volume; the external circulation is that the sludge of the secondary sedimentation tank is returned to the internal circulation anaerobic reactor and the anaerobic tank of A / O, and the phosphorus removal function is realized while supplementing the sludge strains, and the sludge return amount is 1 to 1.2 times the water inlet volume

[0017] Furthermore, the COD concentration of the high-concentration wastewater is ≥3000 mg / L, and the COD concentration of the low-concentration wastewater is <3000 mg / L.

[0018] Furthermore, the total phosphorus in the effluent from the primary sedimentation tank is 8±1 mg / L.

[0019] Furthermore, the total phosphorus in the effluent from the magnetic coagulation sedimentation tank is ≤0.5 mg / L.

[0020] Furthermore, the internal circulation anaerobic reactor is a SWIC internal circulation anaerobic reactor, which has a high load and a small footprint. It is equipped with an efficient umbrella-shaped multi-flow water distribution system and an internal circulation system, has a significant mass transfer effect, greatly shortens the anaerobic start-up time, makes sludge granulation faster, and has a high pollutant removal efficiency.

[0021] By controlling the changes in operating conditions such as the liquid rising flow rate, OLR (organic load), and HRT (residence time), the scale cultivation and secondary scale cultivation of anaerobic granular sludge can be achieved. The mechanism of scale cultivation of anaerobic granular sludge is the combined effect of the internal factors of EPS and the external factors of selection pressure. The TB-EPS in EPS affects the size of the particles, and the LB-EPS affects the bonding ability and structural strength of the particles. The selection pressure affects the biomass concentration, particle size distribution and granulation rate, and also affects the specific gravity, mechanical strength, sedimentation velocity and other properties of the granular sludge. The liquid rising flow rate causes the granular sludge to be subjected to the friction of particle collision and the shear force of the water flow, affecting the surface roughness, sludge shape and integrity of the granular sludge. The characteristics of the organic substrate affect the structure, composition and formation of the granular sludge. The structure of the granular sludge is closely related to the composition of the wastewater, and the complexity of the substrate affects the microbial diversity of the granular sludge. For food wastewater treatment, the rising flow rate is 1.6-2.2m / h, the HRT is 24-36h, and the OLR is 2-4kgCOD / (m 3 ·d), influent COD<5000mg / L.

[0022] The stability of the microbial community structure of anaerobic granular sludge under different OLRs was analyzed by PCR-DGGE. The results showed that the dynamic changes in the bacterial population structure became more and more significant, while the archaeal population structure changed little. The H' index of bacteria had a similar trend to that of archaea, but the H' index of bacteria was much lower than that of archaea. The Margalef richness index DMg of archaea was smaller than that of bacteria, and the dominance index S of archaea was larger than that of bacteria. Studies have shown that the higher the diversity index, the smaller the ecological dominance and the lower the richness. Methanosarcinamazei is easy to grow under low OLR, while Methanosaeta sp. grows under high OLR.

[0023] When the influent COD is about 5000 mg / L, based on the control priority levels mentioned above, the SWIC anaerobic reactor first controls the wastewater rising velocity by adjusting the circulation volume, preferably 2.0 m / h, the HRT is preferably 30 h, and the OLR is preferably controlled at 2.6 kgCOD / (m 3 ·d). Within this control range, the anaerobic sludge granulation degree is obvious and the organic matter removal rate can reach 65% to 75%.

[0024] Comparing the granulation of residual activated sludge and the anaerobic granular sludge to start the anaerobic reactor, the lower the VFA / alkalinity ratio, the more stable the anaerobic system; controlling the VFA / alkalinity value of the SWIC anaerobic reactor within the range of 0.15 to 0.2 can achieve higher OLR and COD removal rates.

[0025] Furthermore, the A / O pool inlet volume load control range is 0.6~0.8kgCOD / (m 3 ·d), in which baking soda is added to the aerobic tank to adjust the water alkalinity (residual alkalinity 100-150 mg / L), the dissolved oxygen range of the aerobic tank is 2-5 mg / L; the surface load control range of the secondary sedimentation tank is 0.5-0.7 m 3 / (㎡·d).

[0026] Furthermore, an aeration and stirring system is arranged in the comprehensive oil-water separation regulating tank, and the effluent from the high-concentration oil-water separation regulating tank is sprayed out through the UPVC perforated pipe in the comprehensive oil-water separation regulating tank.

[0027] Furthermore, the sludge in the secondary sedimentation tank is divided into three paths, one path is returned to the internal circulation anaerobic reactor, one path is returned to the A / O tank, and one path enters the sludge storage tank;

[0028] The sludge in the flotation tank, the primary sedimentation tank and the magnetic coagulation sedimentation tank is pumped into the sludge storage tank.

[0029] Furthermore, the types of chemicals added to the flotation tank are liquid caustic soda (30% concentration), PAC (10% concentration liquid) and PAM (anionic, ≥10 million molecular weight), and the addition amounts of PAC and PAM are 100-300 g / m 3 and 5~10g / m 3 , the pH range is controlled to 8-9 by liquid alkali.

[0030] Furthermore, the types of chemicals added to the primary sedimentation tank are polyferric sulfate (10% concentration liquid) and PAM (anionic type, ≥10 million molecular weight), and the addition amounts of polyferric sulfate and PAM are 120-180 g / m 3 and 5~10g / m 3 .

[0031] Furthermore, the types of dosing in the magnetic coagulation sedimentation tank are liquid alkali (30% concentration), polyferric sulfate (10% concentration liquid), PAM (anionic type, ≥10 million molecular weight) and magnetic powder (300-400 mesh), and the addition amount of polyferric sulfate, PAM and magnetic powder is 50-80g / m 3 2~5g / m 3 and 1~3g / m 3 , the pH range of liquid alkali is controlled at 7 to 8.

[0032] Through the phosphorus removal test of different types of coagulants, it is known that for phosphorus-containing wastewater, the phosphorus removal effect of iron salt is significantly better than that of aluminum salt. 3+ The hydrolysis and polymerization ability is stronger, and it can be hydrolyzed in water to generate [Fe(OH)2] + , [Fe(OH)] 2+ , and [Fe3(OH)6] 3+ The complex ions are adsorbed and bridged to form polymers with a large specific surface area, which can better remove phosphorus through coagulation. The removal rate of total phosphorus by PFS is higher than that of FeCl3 because PFS is a high molecular polymer with better coagulation performance, stronger adsorption and precipitation net capture. Adding a reaction tank and a primary sedimentation tank at the front end and a magnetic coagulation sedimentation tank at the end can reduce the total phosphorus from 50mg / L to about 0.5mg / L, and the precipitated sludge is pumped into the sludge tank for filter press treatment.

[0033] Furthermore, the sludge storage tank uses PAM (cationic type, ≥10 million molecular weight) to adjust the sludge shape, with a dosage of 1-2 g / m 3 .

[0034] The second aspect of the present invention provides a centralized wastewater treatment device for a food park, which is used in the method described in the first aspect of the embodiment, and comprises a comprehensive oil separation regulating tank, an air flotation tank, a primary sedimentation tank, a biochemical water distribution tank, an internal circulation anaerobic reactor, an A / O tank, a secondary sedimentation tank and a magnetic coagulation sedimentation tank connected in sequence;

[0035] It also includes a first grid, a second grid and a high-concentration oil separation regulating tank, the second grid is connected to the high-concentration oil separation regulating tank, and the first grid and the high-concentration oil separation regulating tank are both connected to the comprehensive oil separation regulating tank.

[0036] Furthermore, the mud outlet of the secondary sedimentation tank is connected to the internal circulation anaerobic reactor, the A / O tank and the sludge storage tank;

[0037] The sludge outlets of the air flotation tank, the primary sedimentation tank and the magnetic coagulation sedimentation tank are all connected to the sludge storage tank.

[0038] Beneficial effects of the present invention:

[0039] The present invention collects wastewater from food park enterprises for centralized treatment, and effectively reduces insoluble reducing substances, SS, chromaticity, total nitrogen and total phosphorus in the wastewater through physicochemical pretreatment of front-end flotation tank and primary sedimentation tank, biochemical treatment of middle-end internal circulation anaerobic reactor and A / O tank, and deep physicochemical treatment of terminal magnetic coagulation sedimentation, with good treatment effect and low efficiency. At the same time, the biochemical treatment process adopts the combination of internal circulation and external circulation to realize the self-digestion of sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 The present invention is a flow chart of the centralized wastewater treatment method for a food park. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] This embodiment relates to a method for treating centralized wastewater in a food park, the process of which is as follows: Figure 1 As shown, the following steps are included:

[0044] (1) The enterprise does not need to perform pretreatment, and directly collects high-concentration wastewater (COD ≥ 3000 mg / L) and low-concentration wastewater (COD < 3000 mg / L) from the enterprise. The low-concentration wastewater enters the comprehensive oil separation regulating tank after passing through the first grid, and the high-concentration wastewater is pumped into the comprehensive oil separation regulating tank after passing through the second grid and the high-concentration oil separation regulating tank in turn.

[0045] (2) The effluent from the comprehensive oil separation regulating tank enters the flotation tank, and liquid alkali (30% concentration), PAC (10% concentration liquid) and PAM (anionic type, ≥10 million molecular weight) are added to the flotation reaction zone. The addition amount of PAC and PAM is 280g / m 3 and 6g / m 3 Liquid alkali is automatically added according to the linkage between the online pH meter and the metering pump to control the pH range to 8-9.

[0046] (3) The effluent from the flotation tank flows into the primary sedimentation tank by gravity, and polyferric sulfate (10% concentration liquid) and PAM (anionic type, ≥10 million molecular weight) are added to the reaction zone of the primary sedimentation tank. The addition amount of polyferric sulfate and PAM is 180g / m 3 and 5g / m 3 The reaction water is separated into mud and water through the sedimentation area.

[0047] (4) The effluent from the primary sedimentation tank enters the comprehensive biochemical treatment stage after passing through the biochemical water distribution tank, namely, the SWIC internal circulation anaerobic reactor + A / O tank + secondary sedimentation tank. Among them, the rising flow rate of the SWIC internal circulation anaerobic reactor is 2m / h, the HRT is 30h, and the OLR is 2.6kgCOD / (m 3 ·d). The sludge in the secondary sedimentation tank is returned to the anaerobic tank of the SWIC internal circulation anaerobic reactor + A / O tank, and the nitrification liquid in the aerobic tank of the A / O tank is returned to the anaerobic tank to achieve the denitrification and phosphorus removal of wastewater and the substantial removal of organic matter. The sludge and water mixture is separated in the secondary sedimentation tank, and the supernatant flows into the terminal magnetic coagulation sedimentation tank.

[0048] (5) In the magnetic coagulation precipitation reaction zone, liquid alkali (30% concentration), polyferric sulfate (10% concentration liquid), PAM (anionic type, ≥10 million molecular weight) and magnetic powder (300-400 mesh) were added. The addition amount of polyferric sulfate, PAM and magnetic powder (300-400 mesh) was 65 g / m 3 3.2g / m 3 and 2.8g / m 3 Liquid alkali is automatically added according to the linkage between the online pH meter and the metering pump, the pH range is controlled to be 7-8, and the effluent meets the discharge standards.

[0049] The sludge from the flotation tank, primary sedimentation tank and magnetic coagulation sedimentation tank is pumped into the sludge storage tank. The sludge storage tank uses PAM (cationic type, ≥10 million molecular weight) to adjust the sludge shape, and the dosage is 1.5g / m 3 .

[0050] In this embodiment, the removal of various substances in wastewater by each treatment unit is shown in Table 1:

[0051] Table 1

[0052]

[0053] As can be seen from Table 1, the present invention collects wastewater from food park enterprises for centralized treatment, and effectively reduces the insoluble reducing substances, SS, chromaticity, total nitrogen and total phosphorus in the wastewater through physicochemical pretreatment of the front-end flotation tank and the primary sedimentation tank, the middle-end internal circulation anaerobic reactor and the biochemical treatment of the A / O tank, and the terminal magnetic coagulation sedimentation deep physicochemical treatment. After the treatment, the COD value, ammonia nitrogen, total nitrogen, total phosphorus and other pollution discharge indicators in the wastewater meet the emission standards, and the treatment effect is good and the efficiency is low.

[0054] Another embodiment of the present invention provides a centralized wastewater treatment device for a food park, which is used to implement the method described in the previous embodiment. Figure 1 , including a comprehensive oil-separation regulating tank, a flotation tank, a primary sedimentation tank, a biochemical water distribution tank, an internal circulation anaerobic reactor, an A / O tank, a secondary sedimentation tank and a magnetic coagulation sedimentation tank connected in sequence; also including a first grid, a second grid and a high-concentration oil-separation regulating tank, the second grid is connected to the high-concentration oil-separation regulating tank, the first grid and the high-concentration oil-separation regulating tank are both connected to the comprehensive oil-separation regulating tank.

[0055] Preferably, the sludge outlet of the secondary sedimentation tank is connected to the internal circulation anaerobic reactor, the A / O tank and the sludge storage tank; the sludge outlets of the flotation tank, the primary sedimentation tank and the magnetic coagulation sedimentation tank are all connected to the sludge storage tank.

[0056] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for treating centralized wastewater in a food park, characterized in that: The steps include: S1. Collect enterprise wastewater and classify it into high-concentration wastewater and low-concentration wastewater. The low-concentration wastewater enters the comprehensive oil separation regulating tank after passing through the first grid, and the high-concentration wastewater is pumped into the comprehensive oil separation regulating tank after passing through the second grid and the high-concentration oil separation regulating tank in sequence; S2, the effluent from the comprehensive oil separation regulating tank enters the flotation tank, a demulsifier is added and compressed air is introduced into the wastewater, so that the emulsified oil and suspended particles in the wastewater form foam and float up and separate; S3, the effluent from the flotation tank flows into the primary sedimentation tank by gravity, and polyferric sulfate and polyacrylamide are added to adsorb suspended matter and total phosphorus and capture them by precipitation net; S4, the effluent from the primary sedimentation tank enters the internal circulation anaerobic reactor after temperature control in the biochemical water distribution tank, and the organic matter is decomposed, metabolized and digested by anaerobic bacteria; S5, the effluent of the internal circulation anaerobic reactor flows into the A / O tank by gravity to remove TN, NH3-N and organic matter; S6, the effluent from the A / O tank enters the secondary sedimentation tank to separate mud and water; S7, the effluent from the secondary sedimentation tank flows into the magnetic coagulation sedimentation tank by gravity, and polyferric sulfate, alkali, polyacrylamide and magnetic powder are added to further remove total phosphorus, suspended matter and organic matter; S8. The effluent from the magnetic coagulation sedimentation tank meets the discharge standards.

2. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: The COD concentration of the high-concentration wastewater is ≥3000 mg / L, and the COD concentration of the low-concentration wastewater is <3000 mg / L.

3. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: The total phosphorus in the effluent from the primary sedimentation tank is 8±1 mg / L; the total phosphorus in the effluent from the magnetic coagulation sedimentation tank is ≤0.5 mg / L.

4. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: The internal circulation anaerobic reactor is a SWIC internal circulation anaerobic reactor, the wastewater rising velocity in the reactor is 1.6-2.2 m / h, the residence time is 24-36 h, and the organic load is 2-4 kgCOD / (m 3 ·d), influent COD<5000mg / L, volatile fatty acid / alkalinity value is 0.15-0.

2.

5. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: The A / O pool inlet volume load is 0.6-0.8 kgCOD / (m 3 ·d), in which baking soda is added to the aerobic tank to adjust the residual alkalinity of the water to 100-150 mg / L, and the dissolved oxygen in the aerobic tank is 2-5 mg / L; the surface load of the secondary sedimentation tank is controlled within the range of 0.5-0.7 m 3 / (㎡·d).

6. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: An aeration and stirring system is arranged in the comprehensive oil separation regulating tank, and the effluent from the high-concentration oil separation regulating tank is sprayed out through the UPVC perforated pipe in the comprehensive oil separation regulating tank.

7. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: The sludge in the secondary sedimentation tank is divided into three paths: one path is returned to the internal circulation anaerobic reactor, one path is returned to the A / O tank, and one path enters the sludge storage tank; The sludge in the flotation tank, the primary sedimentation tank and the magnetic coagulation sedimentation tank is pumped into the sludge storage tank.

8. The method for centralized wastewater treatment in a food park according to claim 1, characterized in that: The particle size of the magnetic powder is 300-400 meshes.

9. A centralized wastewater treatment device for a food park, characterized in that: The method used in any one of claims 1 to 8 of the embodiment comprises a comprehensive oil separation regulating tank, an air flotation tank, a primary sedimentation tank, a biochemical water distribution tank, an internal circulation anaerobic reactor, an A / O tank, a secondary sedimentation tank and a magnetic coagulation sedimentation tank connected in sequence; It also includes a first grid, a second grid and a high-concentration oil separation regulating tank, the second grid is connected to the high-concentration oil separation regulating tank, and the first grid and the high-concentration oil separation regulating tank are both connected to the comprehensive oil separation regulating tank.

10. The centralized wastewater treatment device for a food park according to claim 9, characterized in that: The mud outlet of the secondary sedimentation tank is connected to the internal circulation anaerobic reactor, the A / O tank and the sludge storage tank; The sludge outlets of the air flotation tank, the primary sedimentation tank and the magnetic coagulation sedimentation tank are all connected to the sludge storage tank.

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