CN102350104A - Chemical-biological flocculation radiation-flow secondary settler - Google Patents

Abstract

The invention provides a chemical-biological flocculation radial-flow secondary sedimentation tank for sewage treatment. The invention is to set a flocculation reaction zone in the original radial-flow sedimentation tank, and chemically -Biological flocculation, then effluent sedimentation, the characteristic is that the flocculant dosing point is located after the biological treatment, and before the sedimentation, a special flocculation reaction zone is set in the center of the secondary settling tank, which is divided into a central cylinder and an outer cylinder, and the central cylinder is for turbulent flow flocculation zone and steady flow zone, and the outer cylinder is the suspension filter zone and the flocculation effluent zone. The invention can achieve further high-efficiency and low-consumption denitrification and dephosphorization, improve the mud-water separation effect of the secondary sedimentation tank, meet the standard of effluent water quality, reduce the amount of flocculant dosage, and save land use.

Description

A chemical-biological flocculation radial flow secondary sedimentation tank

technical field

The invention belongs to a sewage treatment method, in particular to a chemical-biological flocculation radial flow secondary sedimentation tank.

Background technique

Flocculation technology can be divided into chemical flocculation, biological flocculation and chemical-biological flocculation according to the principle of action.

Chemical flocculation converts pollutants in sewage into sediments by adding chemicals, and then separates solids and liquids and transfers them to sludge. The chemical precipitation of phosphorus is divided into four steps: precipitation reaction, coagulation, flocculation, and solid-liquid separation. According to the different dosing points in the process flow, the phosphate precipitation process has three types: pre-precipitation, cooperative precipitation and post-precipitation. The pre-flocculation and flocculant dosage is large, the impurity components in the water are complex, and the flocculation reaction is relatively complicated; the post-flocculation needs to add additional flocculation and sedimentation devices, which increases the construction cost and land use; collaborative precipitation is in the process of biological treatment. The amount of flocculant added has a certain influence on the biological activity.

Bioflocculation is to improve the removal of suspended and colloidal pollutants by adding bioflocculants. Microbial flocculants are metabolites with flocculation activity produced by microorganisms, mainly composed of glycoproteins, polysaccharides, proteins, cellulose and DNA. As a natural polymer flocculant, it can overcome the shortcomings of inorganic and synthetic organic polymer flocculants, has no secondary pollution to the environment, and is convenient and safe to use. In recent years, bioflocculants have received extensive attention from researchers from various countries, and have also become a direction for the research and development of new flocculants. Studies have shown that bioflocculation can significantly improve the removal effect of organic matter, but the removal effect on phosphorus is poor, and it is difficult to meet the requirements of preventing eutrophication of water bodies.

Chemical-biological flocculation is a chemical-biological integrated sewage treatment process, and now more research is on it as a first-level enhanced process, using sludge reflux, adding chemical flocculants, and aeration and stirring to achieve chemical biological coagulation. purpose of joint action. However, this is still a new type of sewage treatment process. The flocculation reaction pathway between the chemical flocculation machine and microorganisms, whether the chemical flocculants and microorganisms interact with organic matter alone or in combination still needs further research. Moreover, the influent water has only been pretreated, and the water contains more pollutants, and relatively more flocculants need to be added, which increases the operating cost in the later stage, and the complex composition of the water will also affect the effect of the flocculants.

Contents of the invention

The task of the present invention is to provide a chemical-biological flocculation radial flow secondary sedimentation tank to overcome the shortcomings of the prior art, realize the improvement of the mud-water separation effect of the secondary sedimentation tank, improve the impact load resistance of the system, and achieve further denitrification Phosphorus removal, saving investment and land use.

Realize the technical scheme of the present invention is:

The chemical-biological flocculation radial flow secondary sedimentation tank provided by the present invention includes: a sedimentation tank 1, a funnel-shaped downward mud discharge hopper located in the middle of the bottom plane of the sedimentation tank 1, and a mud discharge hopper 2 above which is arranged There is a central cylinder 5, a mud discharge pipe 3 is provided at the bottom of the mud discharge hopper 2, and a horizontally connected water inlet pipe 4 is arranged on the middle part of the side wall of the mud discharge hopper 2, and the water inlet pipe 4 passes through the side wall of the mud discharge hopper 2 At right angles to the center of the mud discharge bucket 2 and extend upwards; 4-6 water outlet holes 6 are equidistantly opened near the top of the outer wall of the central cylinder 5; Near the top, a peripheral water outlet tank 8 surrounding the sedimentation tank 1 is provided; a water outlet pipe 9 is provided at the bottom of the peripheral water outlet tank 8; a mud discharge slot 10 is provided at the bottom of the central cylinder 5; it is characterized in that: the central cylinder 5 The upper half is cylindrical and the lower half is funnel-shaped. The ratio of the cylindrical radius of the upper half of the central tube 5 to the radius of the sedimentation tank 1 is 1:4 to 1:8, and the cylindrical volume of the upper half is the same as that of the lower half. The volume ratio of the half-funnel type is 1.5 to 2.0; there are water outlet holes 6 at equal distances near the top of the side wall of the central cylinder 5, and the ratio of the radius of the rectifying cylinder 7 to the radius of the upper half of the central cylinder 5 is 1.1 to 1.2; The water inlet pipe 4 passes through the side wall of the mud discharge hopper 2 and then passes through the side wall of the funnel-shaped lower half of the central cylinder 5 and ends in the cavity of the funnel-shaped lower half of the central cylinder 5. The water outlet end is a slope-like opening with a downward slope; the water inlet pipe 4 is provided with a dosing pipe 12, and a pipe-type A mixer 11 ; a dosing pump 13 is provided before the dosing pipe 12 is connected to the water inlet pipe 4 .

At the central part of the bottom of the central cylinder 5, 2 to 4 cylindrical bypass columns 14 perpendicular to the bottom plane of the central cylinder 5 may be arranged. The number of 6 water outlet holes near the top of the side wall of the central cylinder 5 is 4-6. The opening slope angle of the outlet end of the water inlet pipe 4 is 40° to 50°, preferably 45°. The inclination angle of the lower half of the funnel-shaped side wall of the central cylinder 5 is 45° to 60°.

The invention provides a chemical-biological flocculation radial-flow secondary sedimentation tank for sewage treatment. The invention is to set a flocculation reaction zone in the original radial-flow sedimentation tank, and chemically -Biological flocculation, and then effluent sedimentation, the characteristic is that the flocculant dosing point is located after the biological treatment, and before the sedimentation, a special flocculation reaction zone is set in the center of the secondary sedimentation tank, which is divided into a central cylinder and an outer cylinder, and the central cylinder is for turbulent flow flocculation zone and steady flow zone, and the outer cylinder is the suspension filter zone and the flocculation effluent zone. The invention can achieve further high-efficiency and low-consumption denitrification and dephosphorization, improve the mud-water separation effect of the secondary sedimentation tank, meet the standard of effluent water quality, reduce the amount of flocculant dosage, and save land use.

In the chemical-biological flocculation radial flow secondary sedimentation tank provided by the present invention, after the biological tank, the chemical flocculant is added to the tubular mixer 11 through the dosing pump 13 through the dosing pipe 12, and the chemical flocculant is polymerized Aluminum ferric chloride (PAFC), the dosage is 10-20 mg per liter, and coagulant aid can be added when the influent water quality is poor. After the chemical flocculant is mixed with the incoming water, it enters the funnel-shaped side wall of the lower half of the central cylinder 5 through the water inlet pipe 4 tangentially, forms a swirling flow around the flow column 14 to make the water flow upward, and forms a funnel-shaped lower half of the central cylinder 5 The medium residence time is 2 to 4 minutes, and medium-speed mixing is carried out to strengthen particle collision and form relatively mature flocs. Then enter the cylindrical upper half of the central cylinder 5, the speed decreases with the rise, this is a slow mixing process, the residence time in the cylindrical upper half of the central cylinder 5 is 6-8 Minutes to form a suspension layer to make the flocs contact with flocculation, and let the flocs grow slowly to form larger flocs. Then it flows into the rectifying cylinder through the outlet hole 13 and enters the sedimentation tank 1 downwards. Settling in the sedimentation tank 1 for 1.5 to 2.5 hours, the mud and water are separated, and the sludge slowly slides into the mud discharge hopper 2 and is discharged through the mud discharge pipe 3, while the upper layer of clear water enters the surrounding water outlet tank 8 and is discharged through the water outlet pipe 9. This scheme organically combines chemical flocculation and biological flocculation, and the process further improves the removal effect of pollutants and the separation effect of mud and water. With the integrated structure, the flocculation and sedimentation are placed in the same reactor, which greatly saves land occupation and energy.

Operation method: During operation, with the water entering the water inlet pipe 4, turn on the dosing pump 13 and add the prescribed dosage through the dosing pipe 12 into the water inlet pipe 4 to mix with the water.

Compared with the prior art, the present invention has the following advantages:

1. Using chemical-biological flocculation: chemical-biological flocculation is a new sewage treatment process with deep integration of chemistry and biology, which organically combines chemical flocculation and biological flocculation;

2. The dosing point of the flocculant is appropriate: the present invention adds the flocculant after the biological treatment and before the secondary sedimentation tank, so as to overcome the large amount of flocculant dosage in the pre-flocculation, the reaction is more complicated and the additional flocculation sedimentation is required for the post-flocculation The problem of the device; adding flocculant in the secondary sedimentation tank, part of the flocculant can work repeatedly in the reflux, which can reduce the amount of flocculant;

3. Flocculation-sedimentation integrated structure: adopting an integrated structure, flocculation and sedimentation are placed in the same reactor, and the flocculation area and the sedimentation area are organically combined through a perforated rectifying plate. It not only saves land occupation, but also greatly saves energy;

4. Improve the mud-water separation effect of the secondary sedimentation tank: add flocculant to make the suspended particles that are not easy to settle form a solid floc, which is easy to settle and improve the mud-water separation effect;

5. Energy saving: the mixed flocculation reaction uses the kinetic energy and potential energy of the incoming water, and there is no energy consumption such as stirring at all, which saves operating costs;

Description of drawings

Fig. 1 is the structural diagram of the secondary sedimentation tank of the prior art, and the position indicated by the numeral mark in the figure is:

1——Sedimentation tank

2 - Mud bucket

3——Mud discharge pipe

4——Water inlet pipe

5——Central barrel

6——Water outlet

7 - rectifier

8——Peripheral water outlet

9——outlet pipe

10——Mud drainage joint

Fig. 2 is the structural diagram of the chemical-biological flocculation radial flow secondary sedimentation tank provided by the present invention, and the parts indicated by the numerals in the figure are:

1——Sedimentation tank

2 - Mud bucket

3——Mud discharge pipe

4——Water inlet pipe

5——Central cylinder

6——Water outlet

7 - rectifier

8——Peripheral water outlet

9——outlet pipe

11——Tube mixer

12—dosing tube

13—dosing pump

14——Around the flow column

Figure 3 is a cross-sectional view of A-A in Figure 2, and the parts indicated by the numerals in the figure are:

1——Sedimentation tank

5——Central barrel

6——Water outlet

7 - rectifier

14——Around the flow column

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

As shown in Figures 1 to 3, the present invention is an improved method for the traditional secondary sedimentation tank, and the central cylinder 5 is transformed in the center of the traditional radial flow secondary sedimentation tank as a chemical-biological flocculation reaction flocculation zone. Secondary sedimentation tank 1 has a diameter of 50 meters. The central cylinder 5 is connected to the sedimentation area of secondary sedimentation tank 1 through rectification cylinder 7. The central cylinder 5 is funnel-shaped with a side wall inclination angle of 45°, a height of 2.0 meters, and a maximum diameter of 5 meters, the central tube 5 is a cylindrical upper half with a height of 1.0 meters and a diameter of 5 meters. The opening slope angle of the water inlet pipe 4 outlet is 45°, and the diameter is 900 mm to form a swirling flow; the bottom of the central cylinder 5 is provided with 4 evenly distributed around-flow columns 14, and the diameter is 100 mm to strengthen the water flow disturbance.

The water inlet pipe 4 will directly send the activated sludge mixed solution mixed with the pipe mixer 11 to the turbulent flocculation area, and the impact pressure of the water outlet of the water inlet pipe will make the water flow have a certain flow rate, and the activated sludge mixed solution reaches the entire turbulent flocculation area. Dynamic flocculation area, where turbulent flocculation is performed to allow the flocs to fully contact.

The water outlet hole 6 that the central cylinder 5 communicates with the rectifying cylinder 7 is set to be 800 mm in height, the distance between the top of the hole and the top of the central cylinder 5 is 200 mm, the number of openings is 4, and the radiation is evenly distributed.

Considering the requirements of influent and effluent water quality and the configuration of the secondary sedimentation tank, the hydraulic retention time of the sewage in the funnel-shaped lower half of the central cylinder 5 is 4 minutes, and the hydraulic retention time in the cylindrical upper half of the central cylinder 5 is 4 minutes. The time is 6 minutes; polyaluminum ferric chloride (PAFC) is used as the flocculant, and the dosage is 20 mg per liter. When the influent water quality is poor, coagulant aid can be added.

The simulation test is carried out in the laboratory, and the removal results of each index are as follows:

1. It has a high removal effect on various forms of phosphorus. The removal rate of total phosphorus (TP) reaches more than 47%, the concentration of TP in the effluent reaches the first-class A standard of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002), and the removal rate of dissolved total phosphorus reaches 40%. Above, the removal rate of phosphate reaches 43%.

2. The removal rate of (SS) has reached 80%, and the effluent SS has reached the first-class A standard of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002).

3. The influent is typical southern domestic sewage, and the influent concentration of chemical oxygen demand (COD) is low, which is lower than the first-class A standard, but this process still has a certain degree of COD removal. This process has different degrees of removal effects on ammonia nitrogen (NH ₃ -N) and total nitrogen (TN).

Claims (7)

1. chemical-biological flocculation radial-flow secondary sedimentation tank; Comprise: sedimentation basin (1), the mud-removing bucket (2) that is the funnel type depression downwards that is positioned at sedimentation basin (1) base plane middle part, mud-removing bucket (2) top are provided with the sidewall middle part that central tube (5), mud-removing bucket (2) bottom be provided with discharge pipeline (3), mud-removing bucket (2) and are provided with the water inlet pipe (4) that a level inserts, and this water inlet pipe (4) passes mud-removing bucket (2) sidewall to mud-removing bucket (2) center right-angle steering and up extends; At equidistant 4-6 the apopore (6) that have of the outer wall proximal portion of central tube (5); Central tube (5) top periphery has rectification tube (7); Proximal portion at sedimentation basin (1) outer wall is provided with the peripheral effluent groove (8) around sedimentation basin (1); The bottom of peripheral effluent groove (8) is provided with an outlet pipe (9); In central tube (5) bottom spoil disposal seam (10) is set; It is characterized in that: the first half of described central tube (5) is column type; Lower Half is funnel type; The radius of central tube (5) first half column type and the radius ratio of sedimentation basin (1) are 1:4 to 1:8, and the first half is the volume of column type and the volume ratio of Lower Half funnel type is 1.5 to 2.0; Sidewall at central tube (5) is closely located the equidistant apopore (6) that has in the top, and the radius ratio of the radius of rectification tube (7) and central tube (5) first half is 1.1 to 1.2; Water inlet pipe (4) passes in the chamber of the Lower Half that is funnel type that the sidewall that passes the Lower Half that is funnel type of central tube (5) behind mud-removing bucket (2) sidewall again terminates in central tube (5), and the water side of water inlet pipe (4) is the downward inclined plane shape opening in inclined-plane; Water inlet pipe (4) is provided with chemical feed pipe (12), and the position between the delivery port of access place of the chemical feed pipe (12) on the water inlet pipe (4) and water inlet pipe (4) is provided with tube mixer (11); Chemical feed pipe (12) inserts water inlet pipe (4) dosing pump (13) is set before.

2. according to right 1 described chemical-biological flocculation radial-flow secondary sedimentation tank, it is characterized in that, be provided with 2 to 4 columned posts (14) that stream at the bottom centre position of central tube (5) perpendicular to the base plane of central tube (5).

3. according to the described chemical-biological flocculation of right 1 radial-flow secondary sedimentation tank, it is characterized in that, the sidewall of central tube (5) closely apopore (6) number at place, top be 4-6.

4. according to right 1 described chemical-biological flocculation radial-flow secondary sedimentation tank, it is characterized in that the water side opening bevel angle of water inlet pipe (4) is 40 ° to 50 °.

5. according to right 3 described chemical-biological flocculation radial-flow secondary sedimentation tanks, it is characterized in that the water side opening bevel angle of water inlet pipe (4) is 45 °.

6. according to right 1 described chemical-biological flocculation radial-flow secondary sedimentation tank, it is characterized in that the inclination angle of the Lower Half funnel type sidewall of central tube (5) is 45 ° to 60 °.

7. according to right 5 described chemical-biological flocculation radial-flow secondary sedimentation tanks, it is characterized in that the inclination angle of the Lower Half funnel type sidewall of central tube (5) is 45 °.

Images