CN100506726C - Iron and steel sewage coagulation sedimentation and filtration treatment system - Google Patents

Abstract

The invention relates to a system of coagulative precipitation and filtering for wastewater in steel industry, especially suitable for wastewater in tail production in steel industry or comprehensive wastewater comprising less than 30% of sewage. The system comprises high-density clarifying tank and filtering tank, and said high-density clarifying tank combines reaction, clarifying and concentration together. There are flocculant reaction area, pre-settling-concentration area and inclined tube separation area, and a flocculating and a pH adjusting tank are installed following it. The filtering tank combines filtering and backwashing together, and it is separated into water distribution area, filtering area, backwashing area and clean water area. The invention overcomes problems of bad effect of precipitation in traditional coagulative precipitation tank, limited control means in normal fast filtering tank, un-thorough backwash, unsealing between cover of movable cover filtering tank and the tank, server device erosion and high operation cost.

Description

Iron and steel sewage coagulation sedimentation and filtration treatment system

technical field

The invention relates to a comprehensive sewage coagulation sedimentation and filtration system, which is especially suitable for the treatment of comprehensive production wastewater in the iron and steel industry or comprehensive sewage mixed with less than 30% domestic sewage.

Background technique

Most of the comprehensive sewage treatment technologies in the iron and steel industry are physical-chemical methods. According to different process combinations, there are mainly two types: flocculation reaction sedimentation tank + ordinary fast filter tank, coagulation sedimentation and lime softening + mobile cover filter tank, and the above two process combinations Due to relatively conservative coagulation, sedimentation and filtration technologies, the volume of the pool is large and the effect of coagulation and sedimentation is not ideal, especially the former is mainly suitable for surface water treatment and is a traditional process for reducing turbidity in water. The content of SS, COD, oil, iron ions, etc. in the comprehensive sewage is high, which leads to the failure of the subsequent filter unit to function normally. In addition, the ordinary fast filter has limited control means and insufficient backwashing, so the treatment efficiency is low; while the latter The coagulation sedimentation and lime softening are separated, the process is lengthy, the functional division of the structure is not obvious, the seal between the cover and the filter grid of the mobile cover filter is not tight, and the equipment is corroded seriously, resulting in the entire process not smooth and the equipment maintenance rate is high. The qualified rate of effluent water drops, which affects the quality of return water, and even destroys the water balance of the entire steel plant.

Contents of the invention

In order to overcome the unsatisfactory coagulation and sedimentation effect of the traditional coagulation sedimentation tank, the limited control means of ordinary fast filter tanks, insufficient backwashing, poor sealing between the cover and tank of the mobile cover filter tank, serious equipment corrosion, and high operating costs, this project The invention provides a coagulation sedimentation and filtration treatment system for iron and steel sewage.

The technical scheme adopted for realizing the purpose of the present invention is: the iron and steel sewage coagulation sedimentation and filtration treatment system comprises high-density clarifier tank, filter tank; Pre-sedimentation-concentration area, inclined pipe separation area, and a post-coagulation and pH adjustment tank are added after the high-density clarification tank. The filter tank integrates filtration and backwashing, and is divided into water distribution area, filtration area, backwashing district.

As a further improvement, the variable-speed mixer in the reaction chamber of the high-density clarifier and the deflector can control the stirring speed, and a conical circulation barrel is set in the pre-sedimentation-concentration area, and a bottom mud scraper is installed at the bottom of the concentration area, and the mud scraper It has the function of automatic rake lifting. The inclined pipe in the inclined pipe separation area adopts an inclination angle of 60°~80° from the horizontal direction. The water inlet weir of the sump is triangular. The water distribution tank wall of the filter tank is provided with small holes, which are arranged horizontally and located above the backwash water surface. The filter layer of the filter tank is a single homogeneous quartz sand filter material. The pipe section is equipped with an automatic adjustment electric control valve, which is linked with the liquid level before filtration. By adjusting the outlet water flow, the constant water level filtration can be achieved. The backwashing water pipe of the filter pool is combined with the backwashing air pipe. Simultaneous backwash, and finally water backwash" three-step flushing method.

In this system, the high-density clarifier will be technically improved and will be re-matched and rationally combined with the filter tank originally used in the water purification plant, and a post-coagulation and pH adjustment tank will be added after the high-density clarifier. Set up a water distribution structure in front of the clarification tank, and the water distribution structure has the functions of dosing and mixing reaction. The flocculation reaction zone consists of a fast stirring zone and a non-stirring zone. The fast stirring zone controls the stirring speed of the mixed water after dosing by the variable speed impeller, and the non-stirring zone can promote the growth and uniformity of alum flowers. The sewage injected with different chemicals enters the flocculation reaction zone of the high-density clarifier from the mixed water distribution structure, and adds high molecular polymers. At the same time, it flows into the concentrated sludge from the sludge concentration zone to form a high-concentration suspended sludge layer to increase Particle collision opportunities, effective adsorption of colloids, suspended solids, oil, COD and BOD and other pollutants. Sludge reflux can not only save 10% of the chemical dosage, but also maintain the suspended solid concentration in the reaction zone at an optimal level, so as to achieve the purpose of optimizing the flocculation reaction. The flocculation reaction occurs under the stirring action of the electric agitator to form larger alum flowers, and the sewage with alum flowers enters the pre-sedimentation-concentration zone. After the sewage after the flocculation reaction enters the pre-sedimentation-concentration area with a large area, the moving speed of the alum flowers slows down, so that most of the suspended solids are precipitated and concentrated in this area. The pre-sedimentation-concentration zone can be divided into upper and lower layers. The upper layer of the conical circulation barrel is concentrated activated sludge for reflux; the lower layer of the conical circulation barrel is mainly residual sludge for discharge. The height of the conical circulation barrel can be adjusted to control the residence time of the sludge, thereby controlling the sludge concentration. The bottom of the sludge concentration area is equipped with a bottom sludge scraper, which scrapes the remaining sludge into the sludge bucket, and is pumped to the sludge system by the sludge discharge pump for dehydration. The inclined tube separation area removes the remaining alum flowers in the water again. After the clarified water is collected from the sump, it enters the post-coagulation tank, and after further reaction and pH adjustment, it is transported to the filter tank for filtration.

The incoming water from the filter passes through the main distribution channel, and then enters the distribution channel of the single tank through the two square inlet holes of the single tank (one of which can be automatically closed by a pneumatic ram, called the cross-sweeping current-limiting ram), and then passes through the two The side hole enters the water distribution tank, then overflows through the small hole at the bottom of the water distribution tank and the top of the tank, evenly enters the filter tank, and then flows into the water distribution and gas distribution chamber at the bottom of the tank through the sand filter layer and long handle filter head, and then flows into the water distribution square hole. In the central air-water distribution channel, the filtered water in the pipe gallery finally flows into the reuse water pool through the outlet valve, water seal well, water outlet weir, clear water main channel, and flushing water storage tank.

The filter tank in the present invention adopts the 3-step flushing method of "air flushing - air and water backflushing at the same time - water flushing". The top of the drainage tank; start the blower, open the air intake valve, and the air enters the water distribution and air distribution chamber at the bottom of the filter evenly through the upper air distribution hole of the air-water distribution channel, and is sprayed out by the long-handled filter head to scrub the impurities on the surface of the filter material And suspended in the water, because the small hole at the bottom of the water distribution tank continues to enter the water, the horizontal surface sweeping will be generated in the filter tank, and the impurities will be pushed to the central drain; start the backwash water pump, open the flushing water valve, at this time, air and water enter at the same time The air-water distribution channel enters the filter evenly through the air distribution square hole, the water distribution square hole and the long-handle filter head, so that the filter material can be further washed, while the horizontal surface cleaning continues; stop the air flushing, wash with water alone, and add Continuous horizontal sweeping of the upper surface flushes all the impurities suspended in the water into the central drainage channel, sinks to the backwash drainage channel, and finally leads to the pretreatment regulating pool before the high-density clarifier through the pipeline.

The beneficial effects of the present invention are: the system can reduce equipment corrosion and operating cost for treating comprehensive iron and steel sewage, smooth technological process, ensure the quality of return water, and realize constant water level and constant flow filtering.

Description of drawings:

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

Fig. 1 is a system structure diagram of the present invention;

Figure 2 is a plan view of a high-density clarifier;

Fig. 3 is A-A sectional view among Fig. 2;

Fig. 4 is filter tank plan view;

Fig. 5 is a B-B sectional view in Fig. 4 .

In the figure: 1. Reaction chamber and deflector, 2. Bottom mud scraper, 3. Sewage well, 4. Outlet weir, 5. Post-coagulation agitator, 6. Inclined pipe, 7. Water collection tank, 8. Circulation And discharge sludge pump, 9, inclined pipe support, 10, circulating sludge pipe, 11, discharge sludge pipe, 12 polymer dosing pipe, 13, incoming water inlet, 14, backwash water pipe, 15, water distribution tank, 16. Filter overflow pipe, 17. Water seal well, 18. Sand filter layer, 19. Backwash air pipe, 20. Backwash drain pipe, 21. Incoming water distribution channel, 22. Incoming water distribution weir, 23. Filter Plate and filter head, 24, high-density clarification tank, 25, filter tank.

Detailed ways

Before selecting the iron and steel sewage coagulation sedimentation and filtration treatment system, firstly calculate the incoming water volume, analyze the incoming water composition, and the water outlet requirements, and select the appropriate coagulation, sedimentation load, and filtration speed to determine the high-density clarifier and filter. Various sizes and related equipment configuration models. Among them, the circulation barrel, mud scraper, inclined pipe, overflow weir, etc. included in the high-density clarifier, and the inlet and outlet water control valves, weir plate, backwash pump, blower, etc. included in the filter are all equipment that match the design parameters. Choose different equipment models according to different coagulation, sedimentation loads, and filtration speeds.

In the figure, the main structure of the high-density clarifier 24 and the filter tank 25 is cast from reinforced concrete; the reaction chamber of the high-density clarifier 24 and the deflector 1 are made of carbon steel or low-alloy steel plate, and are coated with anti-corrosion paint. It is welded and fixed on the bottom plate and surrounding wall of the reaction chamber, and the electromagnetic stirrer is fixed on the pool wall of the reaction chamber through the working bridge, and its stirring speed can be changed by the frequency converter; the inclined tube 6 is made of plastic or glass fiber reinforced plastic, and is supported by the inclined tube 9 Installed in the high-density clarifier at a horizontal angle of 60°; the sump 7 is fixed on the wall of the high-density clarifier by welding at both ends, and the material is stainless steel; the circulating sludge pipe 10, the discharge sludge pipe 11, and the polymer dosing The pipe 12 and the incoming water inlet 13 are all welded steel pipes, which are painted with anti-corrosion paint after derusting; the post-coagulation tank and the high-density clarification tank are cast together by concrete, and the two are integrated.

The sand filter layer 18 of the filter tank 25 is composed of homogeneous quartz sand filter material, and the thickness of the filter material is related to filtration time, backwash intensity, backwash cycle, etc.; backwash pipe 14, filter overflow pipe 16, backwash air pipe 19 , backwash drainage pipe 20 etc. are all welded steel pipes, brush anti-corrosion paint after derusting; The water distribution tank 15, water seal well 17, incoming water distribution channel 21, incoming water distribution weir 22 etc. of the filter are all cast by concrete. into; filter plate and filter head 23 are made of stainless steel and polymer plastics respectively, and are pre-buried in designated positions while the main body of the filter is being constructed. The high-density clarifier and filter are connected by buried welded pipes, and different head losses are considered according to the distance between the two.

After the construction of the above structures is completed and the equipment is installed in place, no-load test run and water-filled operation debugging can be carried out. The general process is: incoming water enters the reaction chamber of the high-density clarifier, and after adding PAM and other chemicals, flocculation occurs under the stirring of the electric mixer. After the sewage after the flocculation reaction enters the pre-sedimentation-concentration area with a large area, the moving speed of the alum flowers slows down, so that most of the suspended solids are precipitated and concentrated in this area. The pre-sedimentation-concentration area can be divided into upper and lower layers. The layer above the conical circulation barrel is concentrated activated sludge for reflux; the layer below the conical circulation barrel is mainly residual sludge for discharge. . The height of the conical circulation barrel can be adjusted to control the residence time of the sludge, thereby controlling the sludge concentration. There is a sludge scraper at the bottom of the sludge concentration area, which scrapes the remaining sludge into the sludge bucket, and is pumped to the sludge system by the sludge discharge pump for dehydration.

The inclined tube separation area removes the remaining alum flowers in the water again. After the clarified water is collected from the sump, it enters the post-coagulation tank, and after further reaction and pH adjustment, it is transported to the filter tank for filtration. The incoming water from the filter passes through the main distribution channel, then enters the single tank distribution channel through the two inlet square holes of the single tank, and then enters the water distribution tank through the holes on both sides, and then flows through the small holes at the bottom of the distribution tank and the overflow at the top of the tank, and enters evenly. The filter tank, then flows into the water distribution and air distribution chamber at the bottom of the pool through the sand filter layer and the long-handle filter head, and then flows into the central air-water distribution channel through the water distribution square hole, and finally passes through the filtered water outlet valve in the pipe gallery and the water seal well , outlet weir, clear water main canal, flushing water storage tank, and flow into the reuse pool. Filter backwashing is to perform air-water combined backwashing according to the set backwashing cycle or the specific fouling situation of the filter material.

Claims (3)

1. A coagulation, sedimentation and filtration treatment system for iron and steel sewage, comprising a high-density clarifier (24), characterized in that: the high-density clarifier (24) integrates reaction, clarification and concentration, and is divided into a flocculation reaction zone, a pre- Settling-concentration zone, inclined tube separation zone, and post-coagulation and pH adjustment tanks are added after the high-density clarification tank (24); after that, a filter tank (25) is set, and the filter tank (25) integrates filtration and backwashing , Divided into water distribution area, filter area, backwash area, clean water area. 2. The iron and steel sewage coagulation sedimentation and filtration treatment system according to claim 1, characterized in that: the variable-speed mixer in the reaction chamber of the high-density clarifier (24) and the deflector (1) can control the stirring speed. The pre-sedimentation-concentration area is equipped with a conical circulation barrel, the bottom of the concentration area is equipped with a bottom scraper (2), the inclined pipe (6) in the inclined pipe separation area adopts an inclination angle of 60° to 80° from the horizontal direction, and the water collection tank (7) The water inlet weir is triangular, and the post-coagulation tank is provided with a variable-speed post-coagulation agitator (5). 3. The iron and steel sewage coagulation sedimentation and filtration treatment system according to claim 1, characterized in that: the wall of the water distribution tank (15) of the filter tank (25) is provided with small holes, the small holes are arranged horizontally, and are located in the backwash Above the water surface, the sand filter layer (18) of the filter tank (25) is a single homogeneous quartz sand filter material, and the pipe section from the filtered outlet pipe of the filter tank (25) to the water seal well (17) is equipped with an automatic adjustment electric control valve , which is linked with the liquid level before filtration, and the constant water level filtration can be achieved by adjusting the outlet water flow rate. Rinse, and finally water backwash" three-step flushing method.

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