CN114180723B - Enhanced aeration aerobic biological fluidized bed sewage treatment process and device - Google Patents

Abstract

The invention provides a sewage treatment process and a sewage treatment device of an aerobic biological fluidized bed for strengthening aeration, wherein sewage is treated by an anoxic biological reactor and then is introduced into the bottom of the aerobic biological fluidized bed, a micro-bubble aerator, a first inner cylinder, a second aerator and a second inner cylinder are sequentially arranged in the aerobic biological fluidized bed from bottom to top, the micro-bubble aerator and the second aerator respectively generate micro-bubbles and macro-bubbles, the sewage flows upwards in the first inner cylinder under the action of the micro-bubbles, and the rise of the bubbles and the aggregation and removal of the micro-bubbles are accelerated under the action of the macro-bubbles when reaching the second inner cylinder; a part of sewage reaching the top of the fluidized bed flows back to the bottom along the gap to form circulating flow; a part of the waste water is returned to the anoxic bioreactor; the sewage quantity and the exhaust quantity of the reflux anoxic bioreactor are controlled in a linkage way through a liquid level meter. The invention not only can improve the sewage treatment effect of the system and save a great amount of energy consumption and occupied area, but also can flexibly treat the sewage quantity and reduce manual regulation.

Description

An aerobic biological fluidized bed sewage treatment process and device with enhanced aeration

technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to an aeration-intensified aerobic biological fluidized bed sewage treatment process and device.

Background technique

With the development of my country's urban scale and the continuous improvement of the degree of industrialization, a large amount of difficult-to-treat industrial sewage and domestic sewage are produced. Sewage treatment plants are facing severe challenges, especially in the field of industrial sewage treatment. The sewage discharge volume is large, the water quality is complex, the toxicity is high, and the nitrogen ammonia and COD are relatively high. At present, the processes commonly used in sewage biological treatment include activated sludge process, suspended packing biofilm process and biological filter. The sewage that can be treated by the activated sludge method requires low sludge concentration and cannot handle high-load sewage, and the sludge is easy to expand, occupies a large area, requires large-scale sedimentation equipment, and has a large amount of residual sludge. The suspended filler biofilm process is to add a certain amount of filler with a density close to water to the reactor to provide a habitat for the growth of microorganisms, increase the biomass and biological species in the reactor, and then improve the treatment efficiency of the reactor. The suspended packing biofilm process has the characteristics of high treatment efficiency and simple operation. However, only suspended fillers are used for treatment, and the effluent contains a higher concentration of particulate matter and suspended matter, resulting in higher turbidity. In the traditional sand filtration process, due to the high density of sand and other fillers, the relative filling rate is low, and the effective utilization rate of the reactor is correspondingly reduced; at the same time, it is easy to cause blockage during the operation of the process, which is not conducive to the operation of the process.

The aerobic biological fluidized bed reactor has a large height-to-diameter ratio, a small footprint, and a high-speed internal circulation in the reactor. It has high sewage treatment efficiency, strong impact resistance, short residence time, and broad application prospects. However, the single aerobic biological fluidized bed process is difficult to degrade macromolecular organic matter, especially in the treatment of industrial sewage, and it is difficult to meet the discharge standards. Usually, it is necessary to use anoxic sewage treatment process and aerobic biological fluidized bed in series to treat industrial sewage.

At the same time, in the aeration stage, there are problems of uneven aeration and high energy consumption for aeration. Aeration equipment energy consumption, oxygenation capacity, oxygen utilization rate, and sludge suspension degree are the main parameters of aeration performance. At present, in the process of aerobic biological treatment of sewage, the size of the bubbles generated by aeration is large, the speed of rising in the sewage is fast, and the residence time is short. It is necessary to increase the aeration rate to maintain the dissolved oxygen in the sewage, which in turn leads to high energy consumption of the aeration equipment, low oxygenation capacity and oxygen utilization rate. When the aeration rate is reduced, it will cause sludge precipitation and reduce the sewage treatment rate.

CN200810113608.X discloses a combined aerobic biological fluidized bed sewage treatment device. The device includes a plurality of aerobic biological fluidized beds connected in parallel. The fluidized beds adopt standardized boxes and can be combined arbitrarily to build different treatment systems, which is beneficial to reduce costs and simplify installation. particles. The treatment device is only an aerobic biochemical treatment device, which occupies a large area, has many interfaces, and is a separate aerobic biological fluidized bed process, which is difficult to degrade macromolecular organic matter, especially in the treatment of industrial sewage, and it is difficult to discharge up to the standard.

Contents of the invention

In order to solve the deficiencies of the prior art, the present invention provides an aerobic biological fluidized bed sewage treatment process and device with enhanced aeration, which uses a combination of fine air bubbles and large air bubbles to enhance aeration, improve sewage treatment efficiency, and save a lot of energy consumption and land occupation.

To achieve the above object, the present invention adopts the following technical solutions:

An aerobic biofluidized bed sewage treatment process with enhanced aeration, using an anoxic bioreactor and an aerobic biofluidized bed to treat sewage. After being treated by the anoxic bioreactor, the sewage is passed into the bottom of the aerobic biofluidized bed. The aerobic biofluidized bed is provided with a micro-bubble aerator, a first inner cylinder, a second aerator and a second inner cylinder in sequence from bottom to top. The gas source is respectively aerated by the micro-bubble aerator and the second aerator to generate micro-bubbles and large bubbles, which are passed into the fluidized bed Under the action of fine air bubbles, the sewage flows upward in the first inner cylinder and strengthens the reaction, and when it reaches the second inner cylinder, it further intensifies the reaction under the action of large air bubbles, and accelerates the rise of the bubbles and the aggregation and removal of the fine air bubbles;

Part of the sewage reaching the top of the aerobic biological fluidized bed flows back to the bottom along the gap outside the first inner cylinder and the second inner cylinder and circulates into the first inner cylinder to form a circulating flow; part of the sewage returns to the anoxic bioreactor; the waste gas generated by the reaction is discharged from the top;

A liquid level gauge is installed on the top of the aerobic biological fluidized bed to control the amount of sewage and exhaust gas discharged from the recirculating anoxic bioreactor, and regulate the pressure on the top of the aerobic biological fluidized bed to ensure normal water discharge;

The sewage treated by the aerobic biological fluidized bed is discharged from the top of the aerobic biological fluidized bed.

The present invention is further provided that the gas-liquid phase feed volume ratio of the micro-bubble aerator is (0.3-1):1; the average diameter of the micro-bubbles is 50-150 μm, the rising speed of the micro-bubbles is 0.005-0.009 m/s, the oxygen kinetic efficiency is 4-5 kg/(kWh), the average diameter of the large bubbles is 2-20 mm, and the hydraulic retention time in the aerobic biological fluidized bed is 4-8 hours.

The present invention is further configured as follows: the top of the aerobic biological fluidized bed is provided with a reflux valve and an exhaust valve to control the amount of sewage and waste gas discharge of the reflux anoxic bioreactor; the water inlet rate at the bottom of the aerobic biological fluidized bed is kept constant; The pressure decreases, reducing the liquid circulation rate in the annulus of the inner and outer cylinders.

The present invention is further configured as follows: the volume ratio of the return flow of sewage in the annulus to the return flow of sewage flowing back to the anoxic bioreactor is (2-4):1; the pressure range at the top of the aerobic biological fluidized bed is 0.2-0.35MPa; the oxygen content in the sewage flowing back into the anoxic bioreactor at the top of the aerobic biological fluidized bed is 0.2-0.5mg/L.

The present invention further sets that the sludge concentration in the aerobic biological fluidized bed is 3-5g/L, the ratio of COD, NH ₃ -N and total P in the aerobic biological fluidized bed is (100-150):(4-6):1, and the volume load of the aerobic biological fluidized bed is 2-6kgCOD/(m ³ ·d).

The present invention is further configured as follows: a part of the sludge discharged from the aerobic biological fluidized bed after solid-liquid separation is sent back to the anoxic bioreactor, and the remaining part is sent to the sludge treatment system for treatment; or a part is sent back to the anoxic bioreactor, a part is sent back to the aerobic biological fluidized bed, and the remaining part is sent to the sludge treatment system for treatment; the sludge reflux ratio of the aerobic biological fluidized bed is (0-0.6):1.

The present invention also provides an aerobic biological fluidized bed sewage treatment device with enhanced aeration. The sewage treatment device includes an anoxic bioreactor and an aerobic biological fluidized bed. The aerobic biological fluidized bed includes an outer cylinder, and the outer cylinder is provided with a first inner cylinder and a second inner cylinder from bottom to top.

The bottom of the outer cylinder is provided with a first gas phase inlet and a sewage inlet, which are respectively connected with the gas-liquid phase inlet of the micro-bubble aerator, and the sewage inlet is connected with the anoxic bioreactor, and the side wall of the outer cylinder is provided with a second gas phase inlet, which is connected with the second aerator;

The top of the outer cylinder is provided with a backflow outlet, a waste gas outlet and a drainage outlet, which are respectively used to return a part of the sewage at the top of the outer cylinder to the anoxic bioreactor, discharge the waste gas at the top and discharge the treated sewage;

The top of the outer cylinder is provided with a liquid level gauge, which is used for linkage control of a return valve and an exhaust valve respectively connected to the return outlet and the waste gas outlet.

The present invention further provides that the sewage treatment device further includes a waste gas treatment system, a mud-water separator and a sludge treatment system, wherein the waste gas treatment system is used to collect and process waste gas produced by the anoxic bioreactor and the aerobic biological fluidized bed; the mud-water separator is connected to the drainage outlet for solid-liquid separation of the sewage treated by the aerobic biological fluidized bed; the sludge treatment system is connected to the sludge outlet of the mud-water separator, and the sludge outlet is connected to the anoxic bioreactor and the aerobic biological fluidized bed.

According to the present invention, the lower end of the first inner tube includes a plurality of micro-bubble aerators, the micro-bubble aerators are uniformly distributed around the axis along the circumference, and are arranged tangentially inclined with the same inclination direction, and the inclination angle α of the micro-bubble aerators is 10°-40°.

The present invention is further configured that the micro-bubble aerator produces a large number of micro-bubbles through liquid-phase swirl shearing, the side wall of the micro-bubble aerator is provided with a liquid-phase tangential inlet, and the bottom end is provided with a gas-phase axial inlet, and the micro-bubble aerator is provided with a mixing chamber connecting the liquid-phase tangential inlet and the gas-phase axial inlet, and an inlet throat is provided between the gas-phase axial inlet and the mixing chamber, and a throat outlet is provided at the upper end of the mixing chamber, and the throat outlet is connected to a spiral shearing blade.

The present invention further provides that the aspect ratio of the mixing chamber is (2-4):1; the ratio of the diameter of the inlet throat to the diameter of the mixing chamber is (0.05-0.3):1; the helix angle β of the helical shearing blade is 20°-50°.

The present invention is further provided that a plurality of second aerators are provided between the second inner cylinder and the first inner cylinder, and the second aerators are rod-shaped aerators with aeration holes opening upwards, and are suspended in the second inner cylinder.

The present invention is further provided that the diameter and length of the first inner cylinder and the second inner cylinder are equal, the ratio of the distance between the two inner cylinders to the diameter of the inner cylinder is (0.3-0.6):1, the ratio of the total height of the two inner cylinders to the height of the aerobic biological fluidized bed is (0.65-0.8):1, and the ratio of the cross-sectional area of the inner cylinder to the area of the annulus between the inner and outer cylinders is 1:1.

The beneficial effects of the present invention are:

(1) The present invention adopts an aerobic biological fluidized bed reactor, which occupies a small area and has a short hydraulic retention time. By returning part of the sewage in the aerobic biological fluidized bed to the anoxic bioreactor, the untreated macromolecular organic matter is hydrolyzed and acidified again into small molecular organic matter, so as to improve the sewage treatment effect of the system. The exhaust valve and return valve of the aerobic biological fluidized bed are controlled through the linkage of the liquid level gauge, and the sewage back flow and top pressure are automatically controlled to realize self-adaptive treatment of sewage and reduce manual regulation.

(2) The present invention utilizes the combination of the micro-bubble aerator and the suspended rod-type aerator to produce a large number of micro-bubbles and large bubbles respectively. By controlling the size of the micro-bubbles, the rising speed of the bubbles in the sewage is controlled, the residence time of the micro-bubbles is increased, and the amount of dissolved oxygen in the sewage is increased. The huge gas-liquid contact area increases the ability of aerobic organisms to obtain oxygen, and the micro-bubbles swirl up to enhance the diffusion speed of the micro-bubbles; Increasing turbulence and enhancing mass transfer can also speed up the aggregation and rising of fine bubbles, reduce the oxygen content of the sewage that flows back to the anoxic bioreactor at the top, and meet the anoxic requirements of the anoxic reaction.

(3) A circulating flow around the inner cylinder is formed in the aerobic biological fluidized bed of the present invention, and the circulating flow rate is greater than the terminal settling velocity of the carrier, the aerator is not easily blocked by settled sludge, and the service life is prolonged.

Description of drawings

Fig. 1 is the process flow chart of sewage treatment process involved in the present invention;

Fig. 2 is the structural representation of the aerobic biological fluidized bed involved in the present invention;

Fig. 3 is the sectional view of B-B plane among Fig. 1;

Fig. 4 is a schematic diagram of the installation angle of the micro-bubble aerator involved in the present invention;

Fig. 5 is the schematic structural view of the micro-bubble aerator involved in the present invention;

Fig. 6 is a structural schematic diagram of the helical shear blade of the micro-bubble aerator involved in the present invention;

Fig. 7 is a sectional view of plane A-A in Fig. 1 .

Among them, 1-anoxic bioreactor, 2-booster pump, 3-heat exchanger, 4-blower, 5-aerobic biological fluidized bed, 6-sewage inlet, 7-first gas phase inlet, 8-second gas phase inlet, 9-reflux outlet, 10-exhaust gas outlet, 11-drainage outlet, 12-level gauge, 13-mud-water separator, 14-water phase outlet, 15-sludge treatment system, 16-sludge pump, 17-exhaust gas treatment system, 18- Valve, 19-return valve.

Detailed ways

Below in conjunction with embodiment the present invention is described in further detail. It should be understood that the following examples are only used to further illustrate the present invention, and should not be interpreted as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the contents of the present invention still belong to the protection scope of the present invention.

Example 1

The present invention provides an aerobic biological fluidized bed sewage treatment process and device with enhanced aeration. The process flow chart is shown in Fig. 1, and the sewage is treated in series by using an aerobic biological fluidized bed device and an anoxic biological sewage treatment device.

The sewage treatment device includes an anoxic bioreactor 1, an aerobic biological fluidized bed 5, a mud-water separator 13, a sludge treatment system 15, and a waste gas treatment system 17. The raw sewage is acidified and hydrolyzed by the anoxic bioreactor 1 to decompose the macromolecular organic matter in the sewage into small molecular organic matter.

2, the aerobic biological fluidized bed 5 includes an outer cylinder 50, the outer cylinder 50 is sequentially provided with a first inner cylinder 51 and a second inner cylinder 52 from bottom to top, the lower end of the first inner cylinder 51 is provided with a micro-bubble aerator 53, and between the second inner cylinder 52 and the first inner cylinder 51 is provided with a second aerator 54, which is used to generate a large number of micro-bubbles and large bubbles respectively; The gas-liquid phase inlet of 3 is connected, and the second gas phase inlet 8 is provided on the side wall of the outer cylinder 50, which communicates with the second aerator 54. The gas source of the fluidized bed 5 is supplied by the blower 4 through the first gas phase inlet 7 and the second gas phase inlet 8 respectively, and the sewage from the anoxic bioreactor 1 is passed through the sewage inlet 6; the sewage passed into the fluidized bed 5 is lifted by a large number of fine air bubbles, flows upward in the first inner cylinder 51 and strengthens the reaction, and reaches the second inner cylinder 52 and is further strengthened under the action of large air bubbles. reaction, and accelerate the rise of bubbles and the accumulation and removal of fine bubbles; the top of the outer cylinder 50 is provided with a backflow outlet 9, an exhaust gas outlet 10 and a drainage outlet 11, and the exhaust gas is discharged from the exhaust gas outlet 10 into the exhaust gas treatment system 17. Due to the density difference between the inside and outside of the first inner cylinder 51 and the second inner cylinder 52, a part of the sewage reaching the top of the fluidized bed 5 flows back to the bottom of the fluidized bed 5 from the annular gap between the inner and outer cylinders and circulates into the first inner cylinder 51 to form a circulating flow; 9 reflows to the anoxic bioreactor 1, the top of the outer cylinder 50 is provided with a liquid level gauge 12, the reflux outlet 9 and the waste gas outlet 10 are respectively connected to a reflux valve 19 and an exhaust valve 18 to control the reflux flow and exhaust volume, and the valve opening is controlled through the linkage control of the liquid level gauge 12 to regulate the amount of sewage flowing back into the anoxic bioreactor 1 and maintain an appropriate pressure at the top of the fluidized bed to ensure normal water discharge.

The sewage treated by the aerobic biological fluidized bed 5 is discharged from the drainage outlet 11 into the mud-water separator 13, the water phase after solid-liquid separation is discharged from the water phase outlet 14 of the mud-water separator 13, and the sludge is discharged from the sludge outlet 20 at the bottom of the mud-water separator 13, and a part of the sludge is sent back to the anoxic bioreactor 1 through the sludge pump 16, and the remaining part is sent to the sludge treatment system 15 for processing, or a part is sent back to the anoxic bioreactor 1, and a part is sent back to the aerobic bioreactor 1. biological fluidized bed 5, and the remaining part is sent to the sludge treatment system 15 for treatment.

Among them, the anoxic bioreactor 1, the mud-water separator 13, and the waste gas treatment system 17 are all conventional technical choices in the field of sewage treatment. For example, the anoxic bioreactor acidifies and hydrolyzes sewage under anoxic conditions;

Further, the heat exchanger 3 is used to maintain the temperature of the sewage at 20-30°C, and use the heat exchanger to control the temperature of the sewage at the optimum temperature for aerobic bacteria to improve their activity and reaction rate and obtain good effluent quality.

Further, as shown in Figures 3 and 4, the lower end of the first inner cylinder 51 is provided with a number of micro-bubble aerators 53, the micro-bubble aerators 53 are uniformly distributed along the circumference around the axis, and are arranged along a tangential inclination with the same inclination direction, all of which are inclined clockwise or counterclockwise. 1 and the inner wall of the second inner cylinder 52 generate a swirl flow to enhance the diffusion speed of the fine air bubbles.

Further, a micro-bubble aerator 53 is provided at the axis of the lower end of the first inner cylinder 51, and the micro-bubble aerator 53 is arranged vertically upward, and together with the micro-bubble aerator 53 distributed along the circumference, a large number of micro-bubbles are generated.

Further, the micro-bubble aerator 53 produces a large number of micro-bubbles through liquid-phase swirl shearing. As shown in FIG. 5 , the side wall of the micro-bubble aerator 53 is provided with a liquid-phase tangential inlet 531, and the bottom end is provided with a gas-phase axial inlet 532. The micro-bubble aerator 53 is provided with a mixing chamber 533 communicating with the liquid-phase tangential inlet 531 and the gas-phase axial inlet 532. An inlet throat 534 is provided between the gas-phase axial inlet 532 and the mixing chamber 533. The upper end of the mixing chamber 533 is provided with a throat outlet 535 , and the throat outlet 535 is connected with a helical shear blade 536 . Sewage enters the mixing chamber 533 from the liquid-phase tangential inlet 531 to form a swirling flow. Gas is passed through the gas-phase axial inlet 532 and compressed by the inlet throat 534 before entering the mixing chamber 533. A large number of fine bubbles are generated under the action of the liquid-phase swirling shear, and the gas-liquid mixture containing a large number of fine bubbles is compressed and discharged from the throat outlet 535, and enters the first inner cylinder 51 after being further sheared by the spiral shearing blade 536.

Further, the aspect ratio of the mixing chamber 533, that is, the ratio of the height to the diameter of the mixing chamber is (2-4): 1, preferably 2.8: 1; the ratio of the diameter of the inlet throat 534 to the diameter of the mixing chamber 533 is 0.05-0.3, preferably 0.1; The volume ratio is (0.3-1):1.

Further, as shown in FIG. 7 , a plurality of second aerators 54 are provided between the second inner cylinder 52 and the first inner cylinder 51. The second aerators 54 are rod-shaped aerators with the aeration holes 541 opening upwards. They are suspended in the second inner cylinder 52 and are used to generate large-sized air bubbles. They swing freely with the aeration process to enhance the uniformity of aeration, and their swings will not interfere with each other. Preferably, the second aerator 54 is suspended in the inner cylinder by a soft steel wire.

Further, the diameter and length of the first inner cylinder 51 and the second inner cylinder 52 are equal, the ratio of the distance between the two inner cylinders to the diameter of the inner cylinder is (0.3-0.6):1, the ratio of the total height of the two inner cylinders to the height of the aerobic biological fluidized bed 5 is (0.65-0.8):1, and the ratio of the cross-sectional area of the inner cylinder to the annulus area between the inner and outer cylinders is 1:1.

Further, the first inner cylinder 51 and the second inner cylinder 52 are fixed in the aerobic biological fluidized bed 5, and the turbulence of the air bubbles is prevented from being shaken by axial fixing and circumferential fixing. Preferably, the materials of the first inner cylinder 51 and the second inner cylinder 52 can be selected from acrylic glass or stainless steel.

Further, the blower 4 provides air source feed for the micro-bubble aerator 53 and the second aerator 54, and the micro-bubble aerator 53 below generates a group of micro-bubbles. The average diameter of the micro-bubbles is 50-150 μm. Due to the inclined installation of the aerator, the group of micro-bubbles can generate a gas-liquid mixture that swirls around the inner wall of the first inner cylinder 51, increasing the contact probability of gas-liquid-solid three-phase, making it easier for aerobic bacteria to take up oxygen; reaching the second inner cylinder 5 above At 2 o'clock, the second aerator 54, that is, the aeration rod generates large bubbles, the average diameter of which is 2-20mm, and the aeration rod is subjected to the reaction force of the gas to swing back and forth, resulting in turbulence, which makes the aeration more uniform and enhances the mixing effect; the mixed liquid outside the first inner cylinder 51 and the second inner cylinder 52 has a low gas content, and under the action of the density difference, it flows back to the bottom of the fluidized bed 5 along the annular gap between the inner and outer cylinders, and when it reaches the bottom, it re-enters the interior of the inner cylinder to form a first inner cylinder 51. And the circulating flow centered on the second inner cylinder 52 to increase the turbulence and mixing effect of the entire fluidized bed, and the circulating flow rate is greater than the terminal sedimentation velocity of the carrier, the aerator is not easy to be blocked by settled sludge, and the service life is prolonged.

Further, the ascending speed of fine bubbles in the aerobic biological fluidized bed 5 is 0.005-0.009m/s, the oxygen kinetic efficiency is 4-5kg/(kW h), and the hydraulic retention time is 4-8 hours. In the aerobic biological fluidized bed 5, the rising speed of the bubbles in the sewage is controlled by reducing the size of the bubbles, increasing their residence time in the sewage, increasing the amount of dissolved oxygen in the sewage, and aeration. Blast volume, save energy consumption.

Further, there will still be a part of the macromolecular organic matter that has not been hydrolyzed and acidified by anoxic reaction in the sewage reacted by the aerobic biological fluidized bed 5. The aerobic bacteria in the aerobic biological fluidized bed 5 cannot ingest and metabolize it, and need to return to the anoxic bioreactor 1 for hydrolysis and acidification to decompose into small molecular organic matter, which is conducive to the complete ingestion reaction of aerobic organisms and improves the drainage quality. Further, the volume ratio of the sewage return flow in the annulus of the inner and outer cylinders to the sewage return flow back to the anoxic bioreactor is (2-4):1.

Simultaneously, the large air bubbles produced by the aeration rod in the second inner cylinder 52 can speed up the coalescence and rise of fine air bubbles, reduce the oxygen content of the sewage at the top of the aerobic biological fluidized bed 5 and return to the anoxic bioreactor 1, and its oxygen content is 0.2-0.5mg/L, which meets the anoxic requirements of the anoxic reaction and prevents the bacterial activity of the anoxic reaction from being affected.

Further, the liquid level gauge 12 controls the reflux valve 19 and the exhaust valve 18 in linkage to regulate the amount of sewage in the reflux anoxic bioreactor 1 and maintain an appropriate pressure at the top of the fluidized bed to ensure normal water outlet. Specifically, the water inflow rate at the bottom of the aerobic biological fluidized bed 5 is kept constant. The flow valve 19 reduces the reflux flow of the reflux anoxic reaction, and the exhaust valve 18 is opened to reduce the internal pressure of the fluidized bed, reducing the liquid circulation rate in the annulus of the inner and outer cylinders.

Further, the pressure range at the top of the aerobic biological fluidized bed 5 is 0.2-0.35 MPa.

Further, the sludge reflux ratio of the aerobic biological fluidized bed 5 is (0-0.6): 1, the sludge reflux ratio refers to the volume ratio of the sludge reflux rate to the water inflow of the device, the sludge reflux rate refers to the amount of sludge flowing back to the bottom of the aerobic biological fluidized bed 5, and the device inflow refers to the amount of sewage entering the aerobic biological fluidized bed 5.

Further, the sludge concentration of the aerobic biological fluidized bed 5 is 3-5g/L, the ratio of COD, NH ₃ -N and total P in the aerobic biological fluidized bed 5 is (100-150):(4-6):1, and the volume load of the aerobic biological fluidized bed 5 is 2-6kgCOD/(m ³ ·d).

Example 2

The aerobic biological fluidized bed sewage treatment process and device described in Example 1 were used to treat a certain petrochemical comprehensive sewage.

The influent pH value of the sewage is 7.0, the CODcr is 670mg/L, and the SS is 170mg/L. Add 2g/L of activated sludge into the aerobic biological fluidized bed, carry out 2 days of bacterial culture, and record the biological concentration in the fluidized bed as 6g/L.

The aeration rate of the aerobic biological fluidized bed is 2m ³ /h, wherein the total aeration rate of the fine bubble generator is 1.2m ³ /h, and the aeration rate of the second aerator is 0.8m ³ /h. The hydraulic retention time in the aerobic biological fluidized bed is 5 hours, and the oxygen content of the sewage in the reflux anoxic bioreactor is in the range of 0.2-0.5 mg/L.

After the process treatment, the measured water quality is: CODcr is 78mg/L, SS is 7mg/L, pH value is 7.2; CODcr volume load is 3.6COD/(m ³ ·d), CODcr removal rate is 88.4%, SS removal rate is 95.8%.

Comparative example 2

The aerobic biological fluidized bed sewage treatment process and device described in Example 1 were used to treat a certain petrochemical comprehensive sewage.

Influent water quality conditions, sewage treatment process and device are the same as in Example 2, the difference is that no second aerator is installed in the aerobic biological fluidized bed, only a micro-bubble aerator is installed.

Since there are no large bubbles in the aerobic biological fluidized bed to promote the accumulation and removal of fine bubbles, the oxygen content of the sewage is still relatively high when it reaches the top of the aerobic biological fluidized bed, about 0.8-1.5 mg/L, so that the oxygen content of the sewage returning to the anoxic bioreactor does not meet the low oxygen content condition.

After the process treatment, the final measured water quality is: CODcr is 120mg/L, SS is 9mg/L, pH value is 7.2; CODcr volume load is 3.0COD/(m ³ ·d), CODcr removal rate is 82.1%, SS removal rate is 94.7%.

Example 3

The aerobic biological fluidized bed wastewater treatment process and device described in Example 1 were used to treat a certain coal-to-ethylene glycol wastewater.

The average CODcr of the wastewater influent is 730 mg/L, the NH ₃ -N is 62 mg/L, and the TN is 237 mg/L. The aeration rate of the aerobic biological fluidized bed is 5m ³ /h, wherein the total aeration rate of the fine bubble generator is 3.6m ³ /h, the second aerator is a rod aerator, the aeration rate is 1.4m ³ /h, and the hydraulic retention time in the aerobic biological fluidized bed is 8 hours.

After the process treatment, the final measured water quality is: CODcr is 57 mg/L, NH ₃ -N is 7 mg/L, TN is 46 mg/L, and the removal rates of COD, NH ₃ -N, and TN are respectively 92.2%, 88.7%, and 80.6%.

Comparative example 3

The aerobic biological fluidized bed wastewater treatment process and device described in Example 1 were used to treat a certain coal-to-ethylene glycol wastewater.

Influent water quality conditions, sewage treatment process and device are the same as in Example 3, the difference is that: the second aerator in the aerobic biological fluidized bed is an annular bubbler, and the annular bubbler interferes with the upstream sewage, and at the same time, the aeration of the annular bubbler in the aerobic biological fluidized bed is not uniform, and the fine bubbles cannot gather and escape locally.

After the process treatment, the final measured water quality is: CODcr is 106 mg/L, NH ₃ -N is 11 mg/L, TN is 62 mg/L, and the removal rates of COD, NH ₃ -N, and TN are 85.5%, 82.2%, and 73.8%, respectively.

Claims (13)

1. The sewage treatment process of the aerobic biological fluidized bed for strengthening aeration adopts an anoxic bioreactor and an aerobic biological fluidized bed for combining treatment, and is characterized in that sewage is treated by the anoxic bioreactor and then is introduced into the bottom of the aerobic biological fluidized bed, a micro-bubble aerator, a first inner cylinder, a second aerator and a second inner cylinder are sequentially arranged in the aerobic biological fluidized bed from bottom to top, an air source is respectively aerated by the micro-bubble aerator and the second aerator to respectively generate micro-bubbles and large bubbles, the sewage introduced into the fluidized bed flows upwards in the first inner cylinder under the action of the micro-bubbles and strengthens the reaction, the sewage reaches the second inner cylinder to further strengthen the reaction under the action of the large bubbles, the rising of the bubbles and the coalescence and removal of the micro-bubbles are accelerated, the average diameter of the micro-bubbles is 50-150 mu m, and the average diameter of the large bubbles is 2-20mm;

part of sewage reaching the top of the aerobic biological fluidized bed flows back to the bottom along an annular gap outside the first inner cylinder and the second inner cylinder and circulates into the first inner cylinder to form circulating flow; a part of sewage flows back to the anoxic bioreactor; the waste gas generated by the reaction is discharged from the top;

the top of the aerobic biological fluidized bed is provided with a liquid level meter, the sewage quantity and the waste gas discharge quantity of the reflux anoxic bioreactor are controlled in a linkage way, the pressure of the top of the aerobic biological fluidized bed is regulated and controlled, and the normal water outlet is ensured;

and the sewage treated by the aerobic biological fluidized bed is discharged from the top of the aerobic biological fluidized bed.

2. The process according to claim 1, wherein the fine bubble aerator has a gas-liquid phase feed volume ratio of (0.3-1): 1, the rising speed of the micro-fine bubbles is 0.005-0.009m/s, the oxygen power efficiency is 4-5 kg/(kW.h), and the hydraulic residence time of the aerobic biological fluidized bed is 4-8 hours.

3. The treatment process according to claim 1, wherein a reflux valve and an exhaust valve for regulating and controlling the sewage amount and the exhaust gas discharge amount of the reflux anoxic bioreactor are arranged at the top of the aerobic biological fluidized bed, the water inlet rate at the bottom of the aerobic biological fluidized bed is kept constant, when the liquid level is too high, the reflux valve is increased, the reflux amount of the reflux anoxic reaction is increased, the exhaust valve is closed, the pressure increase increases the annular gap liquid circulation rate and ensures the water outlet; when the liquid level is too low, the reflux valve is reduced, the reflux quantity of the reflux anoxic reaction is reduced, the exhaust valve is opened, the internal pressure of the fluidized bed is reduced, and the circulation rate of the annular space liquid of the inner cylinder and the outer cylinder is reduced.

4. The process according to claim 1, wherein the volume ratio of the return of the sewage in the annulus to the return of the sewage flowing back to the anoxic bioreactor is (2-4) 1; the pressure range of the top of the aerobic biological fluidized bed is 0.2-0.35MPa; the oxygen content in the sewage of the reflux anoxic bioreactor at the top of the aerobic biological fluidized bed is 0.2-0.5mg/L.

5. The process according to claim 1, wherein the sludge concentration in the aerobic biological fluidized bed is 3-5g/L, and the COD and NH in the aerobic biological fluidized bed are ₃ -the ratio of N to total P is (100-150): (4-6): 1, the volume load of the aerobic biological fluidized bed is 2-6 kgCOD/(m) ³ •d)。

6. The treatment process according to claim 1, wherein a part of sludge after solid-liquid separation of the sewage discharged from the aerobic biological fluidized bed is returned to the anoxic bioreactor, and the remaining part is sent to a sludge treatment system for treatment; or a part of the sludge is sent back to the anoxic bioreactor, a part of the sludge is sent back to the aerobic biological fluidized bed, and the rest of the sludge is sent to a sludge treatment system for treatment; the sludge reflux ratio of the aerobic biological fluidized bed is (0-0.6): 1.

7. an aerobic biological fluidized bed sewage treatment device for strengthening aeration, which comprises an anoxic bioreactor and an aerobic biological fluidized bed, and is characterized in that,

the aerobic biological fluidized bed comprises an outer cylinder, wherein a first inner cylinder and a second inner cylinder are arranged in the outer cylinder from bottom to top, a micro-bubble aerator is arranged at the lower end of the first inner cylinder, a second aerator is arranged between the second inner cylinder and the first inner cylinder and is used for generating a large number of micro-bubbles and macro-bubbles respectively, the average diameter of the micro-bubbles is 50-150 mu m, and the average diameter of the macro-bubbles is 2-20mm;

the bottom of the outer cylinder is provided with a first gas phase inlet and a sewage inlet which are respectively communicated with the gas-liquid phase inlet of the micro-bubble aerator, the sewage inlet is communicated with the anoxic bioreactor, and the side wall of the outer cylinder is provided with a second gas phase inlet which is communicated with the second aerator;

the top of the outer cylinder is provided with a reflux outlet, an exhaust gas outlet and a drainage outlet which are respectively used for refluxing part of sewage at the top of the outer cylinder to the anoxic bioreactor, and discharging the exhaust gas at the top and the treated sewage;

the top of the outer cylinder is provided with a liquid level meter which is used for controlling a reflux valve and an exhaust valve which are respectively connected with the reflux outlet and the exhaust outlet in a linkage way.

8. The wastewater treatment plant of claim 7, further comprising an exhaust gas treatment system, a sludge-water separator, and a sludge treatment system, wherein the exhaust gas treatment system is configured to collect and treat exhaust gas generated by the anoxic bioreactor and the aerobic biological fluidized bed; the mud-water separator is connected with the drainage outlet and is used for solid-liquid separating the sewage treated by the aerobic biological fluidized bed; the sludge treatment system is connected with a sludge outlet of the sludge-water separator, and the sludge outlet is connected with the anoxic bioreactor and the aerobic biological fluidized bed.

9. The sewage treatment apparatus according to claim 7, wherein the first inner cylinder lower end comprises a plurality of micro-bubble aerators which are uniformly distributed circumferentially around the shaft center and are arranged in a tangential tilt manner, the tilt directions are uniform, and the tilt angle α of the micro-bubble aerators is 10 ° to 40 °.

10. The sewage treatment device according to claim 7, wherein the micro-bubble aerator produces a large number of micro-bubbles through liquid phase rotational flow shearing, a liquid phase tangential inlet is arranged on the side wall of the micro-bubble aerator, a gas phase axial inlet is arranged at the bottom end of the micro-bubble aerator, a mixing cavity which is communicated with the liquid phase tangential inlet and the gas phase axial inlet is arranged in the micro-bubble aerator, an air inlet throat is arranged between the gas phase axial inlet and the mixing cavity, a throat outlet is arranged at the upper end of the mixing cavity, and the throat outlet is connected with a spiral shearing blade.

11. The wastewater treatment apparatus of claim 10, wherein the ratio of height to diameter of the mixing chamber is (2-4): 1, a step of; the ratio of the diameter of the air inlet throat to the diameter of the mixing chamber is (0.05-0.3): 1, a step of; the helix angle beta of the helical shear blade is 20-50 degrees.

12. The sewage treatment apparatus according to claim 7, wherein a plurality of second aerators are provided between the second inner cylinder and the first inner cylinder, and the second aerators are rod-shaped aerators with aeration holes opening upwards and are suspended in the second inner cylinder.

13. The wastewater treatment device of claim 7, wherein the first inner cylinder and the second inner cylinder are equal in diameter and length, and the ratio of the space between the two inner cylinders to the diameter of the inner cylinder is (0.3-0.6): 1, the ratio of the total height of the two inner cylinders to the height of the aerobic biological fluidized bed is (0.65-0.8): 1, the ratio of the sectional area of the inner cylinder to the annular space area between the inner cylinder and the outer cylinder is 1:1.