CN117566900B - Micro-oxygen aeration biochemical filter tank for wastewater treatment - Google Patents

Abstract

The invention provides a micro-aerobic biochemical filter for wastewater treatment, which belongs to the field of environmental engineering, and comprises a sludge collecting hopper arranged at the bottom and a cylindrical filter main body arranged above the sludge collecting hopper, wherein a water distributor, an aerator, a water distribution pipe, a filter plate, a supporting layer, a vesuvianite filter layer, a plastic filter layer, a filter material blocking net, a solid collecting tank and a three-phase separator are arranged in the filter main body from bottom to top. The invention provides a micro-aerobic biochemical filter with novel combined filler, which has the function of a secondary sedimentation tank, and achieves the purposes of excellent backwashing effect, easy film hanging of a microbial film, quick starting, quick propagation speed, good heat preservation performance and high oxygen transmission efficiency, and has remarkable effects on energy conservation and consumption reduction.

Description

A micro-oxygen aeration biochemical filter for wastewater treatment

Technical Field

The invention belongs to the technical field of wastewater treatment, and in particular relates to a micro-oxygen aeration biochemical filter for wastewater treatment.

Background Art

Micro-aeration aeration biofilter is a kind of equipment that uses biological methods to treat sewage. The main principle is to use the biofilm formed by microorganisms on the surface of the filter material to decompose various pollutants in the water through their metabolic activities. This equipment combines biological treatment and filtration in one, and can effectively remove various pollutants in the water. The key point to determine the effect of this equipment and process lies in the selection of filter materials, and the backwashing process determines whether the filter can operate stably and efficiently.

Suitable filter media should be able to increase the contact efficiency between biofilm and sewage, and should also be suitable for the growth of microorganisms to promote the formation of biofilm. Although the commonly used traditional fillers such as quartz sand, zeolite, ceramsite and other plastic products are low in cost, they have defects such as insufficient strength, poor acid and alkali resistance, difficulty in regeneration or poor adsorption capacity; although biological activated carbon has excellent performance indicators, it is expensive and has poor promotion. Therefore, finding a filter filler that can replace traditional filter media and is economical and easy to obtain has become a technical difficulty in promoting the use of filter tanks. Volcanic rock is a glassy lava with dense pores. The reason for its porosity is that the pressure change caused by the change in magma temperature before and after the volcanic eruption causes the internal gas to overflow and expand rapidly. Volcanic rock has many pores, large specific surface area, high strength, heat insulation, acid and alkali resistance, corrosion resistance, no secondary pollution, and strong reusability. From the perspective of hydraulics, volcanic rock as a biological filter material has no sharp shape and large pore size, so it has low resistance to water, requires less filter material and saves energy. Studies have shown that volcanic rock, as a biological filter material, not only does not affect the activity of microorganisms, but its surface carries a positive charge that is conducive to the growth of microorganisms. It is highly hydrophilic and can provide a place for enrichment and insulation for microorganisms, making it an ideal filter material for filter beds.

During the long-term operation of the micro-aerobic aerated biofilter, the physical adsorption of the solid suspended matter contained in the wastewater by the filter material and the biological flocculation of the biofilm often lead to the continuous filling of the pores at the junction of the surface layer of filter material and different layers of filter material in actual treatment, and the continuous metabolism of microorganisms on the surface of the filter material, the continuous renewal of the formed biofilm, and the continuous accumulation of the detached biofilm in the gaps between the same filter materials, resulting in smaller and smaller gaps, smaller and smaller water flow and oxygen transfer efficiency, and larger and larger head losses, resulting in blockage, which inevitably leads to frequent backwashing. Therefore, the backwashing of the micro-aerobic aerated biofilter is one of the key factors that determine whether the filter can operate stably and for a long time. If the filter material is not flushed sufficiently, agglomeration may occur, resulting in poor effect during process operation and unsatisfactory effluent water quality. If the flushed lumps and large particles are not discharged in time and remain in the filter tank, the frequency of filter tank backwashing will increase, the treatment load of the entire filter tank will be reduced, which will not only affect the efficiency and stability of the filter tank in treating wastewater, but also greatly increase the energy consumption of the filter tank. The backwashing process uses the pressure of water and/or air to flush out the blocked and compacted filter material, and uses the impact of water and/or air to flush out the detached biofilm, lumps and small particles, and discharge them out of the filter tank with the water flow. However, how to discharge these substances cleanly is the key to whether the structure of the biochemical filter tank including the backwashing system is reasonable.

Patent CN201220061252.1 relates to an aerated biological filter based on Hainan volcanic rock filler, including a circular tower-shaped aerated biological filter, the aerated biological filter including a backwash water inlet, a backwash air inlet, a water inlet, a filter material support plate, a pebble support layer, an air inlet aeration pipe, a filler outlet, a volcanic rock filler layer, a sedimentation area, a filler inlet, an inclined plate sedimentation area, a clear water area, a water outlet, a water outlet, and a backwash overflow. The utility model utilizes the excellent properties of Hainan volcanic rock filter material to effectively achieve deep treatment of low-concentration domestic wastewater, remove suspended matter, COD and ammonia nitrogen, and has the characteristics of strong load resistance, high treatment efficiency and low cost.

Patent CN202320238568 provides an ozone volcanic rock aerated biological filter, including a tank body with an inlet pipeline at the lower end and an outlet pipeline at the upper end, an ozone generating system connected to the inlet pipeline, a backwash aeration system at the lower end of the tank body, and a filter layer with attached biofilm at the upper end of the tank body, and also includes a filter plate below the filter layer, a plurality of filter heads with downward water spraying function are installed on the filter plate, the filter plate and the lower space constitute a water distribution chamber, the water distribution chamber is connected to the backwash air inlet pipeline and the backwash water inlet pipeline, the backwash outlet pipeline is located at the upper part of the tank body, and the filter layer is a volcanic rock filter material layer. This application simultaneously performs biological treatment, ozone oxidation and volcanic rock adsorption treatment on sewage in one device, improves the biodegradability of sewage, improves the utilization rate of ozone, and reduces the organic content in sewage.

However, the backwashing system in the above-mentioned biofilter and the matching arrangement of the backwashing system and the biofilter layer structure are not energy-efficient enough. The art needs a new micro-oxygen aerated biofilter for wastewater treatment, which can operate stably and for a long time with low energy consumption.

Summary of the invention

Therefore, the present invention provides a micro-oxygen aerated biochemical filter for wastewater treatment, the biochemical filter is used for treating tunnel construction wastewater, the biochemical filter comprises a mud collecting bucket (3) arranged at the bottom and a cylindrical filter body arranged above the mud collecting bucket (3), in which a water distributor (16), an aerator (15), an air distribution pipe, a filter plate (19), a supporting layer (14), a volcanic rock filter layer (13), a plastic filter layer (12), a filter material retaining net (21), a solid matter collecting filter (23), and a filter plate (24) are arranged from bottom to top. A collecting tank (10) and a three-phase separator (8), wherein the top of the three-phase separator (8) extends above the highest position of the liquid level in the biochemical filter and is used to discharge the separated gas to the outside of the biochemical filter, the outer wall (17) of the solid collecting tank (10) is the inner wall of the filter body or the outer wall and the inner wall of the filter body are overlapped, and the inner wall (18) of the solid collecting tank (10) is in the shape of a truncated cone with a shorter diameter at the top and a longer diameter at the bottom, and a tank bottom is provided between the outer wall (17) and the inner wall (18). The bottom plate of the three-phase separator (8) is provided with a mud discharge port and a mud discharge pipe above the bottom plate and on the side wall of the filter tank body; the solid-liquid separation section of the three-phase separator (8) is located at the bottom and has a conical structure; a water flow channel for clean water and dirty water to pass through is formed between the bottom edge of the three-phase separator (8) and the inner wall of the filter tank body; a sewage discharge pipe (20) for discharging dirty water generated during backwashing and a sewage discharge pipe (21) for discharging waste water are sequentially provided from bottom to top above the bottom edge of the three-phase separator (8) and on the side wall of the filter tank body. The invention relates to an overflow trough (7) for collecting clean water generated during the treatment process, the water distributor (16) is connected to a water inlet pump (4) arranged outside the filter tank body, the aerator (15) is connected to an aerator (5) arranged outside the filter tank body, and the air distribution pipe is connected to a backwash fan (22) arranged outside the filter tank body; an emptying pipe (1) and a mud pump (23) arranged on the emptying pipe (1) are arranged at the bottom of the mud collecting hopper (3), as well as a backwashing water pipe and a backwashing water pump (2) connected to the emptying pipe (1).

In a specific embodiment, a drain pipe (9) and a drain valve for discharging clean water are provided at the bottom of the overflow tank (7), and the biochemical filter is preferably used for treating wastewater from high-cold and plateau tunnel construction.

In a specific embodiment, the mud discharge pipe comprises a first mud discharge pipe (6) and a second mud discharge pipe (11) which are symmetrically arranged.

In a specific embodiment, a heat-insulating layer is provided on the outer wall of the filter tank body, and the heating wire (24) is wrapped by heat-insulating cotton (25) to form the heat-insulating layer. Preferably, tin foil for decoration and wrapping is provided on the outer side of the heat-insulating layer.

In a specific embodiment, the bottom edge height of the three-phase separator (8) is higher than the top edge height of the solid matter collecting tank (10), and the top of the three-phase separator (8) is a circular pipe for exhaust.

In a specific embodiment, the supporting layer (14) is a pebble layer, wherein the particle diameter is 2-3 cm and the density is 2.3-2.6 g/cm ³ .

In a specific embodiment, the height of the volcanic rock filter layer (13) is 0.6-1.2 m, the particle diameter thereof is 3-5 cm, the density is 1.5-1.8 g/ ^cm3 , and the porosity is 60%-80%.

In a specific embodiment, the height of the plastic filter layer (12) is 0.4-0.8 m, the diameter of the spherical plastic particles therein is 2-3 cm, the density is 1.1-1.3 g/cm ³ , and the porosity is 50%-70%.

In a specific embodiment, the filter material retaining net (21) is arranged 20 to 40 cm above the plastic filter layer (12).

In a specific embodiment, the filter material retaining net (21) is a stainless steel triangular mesh retaining net.

In general, the present invention aims at the shortcomings of incomplete discharge of particulate matter during the backwashing process of the micro-aerobic aeration biochemical filter, high backwashing energy consumption and low microbial activity at low temperature. A three-phase separator and a solid collection tank are arranged above the filter layer, and volcanic stone and plastic fillers are used as filter materials to optimize the filter structure. A micro-aerobic aeration biochemical filter using a new type of combined filler is proposed. The micro-aerobic aeration biochemical filter has the function of a secondary sedimentation tank, achieves the purposes of excellent backwashing effect, easy microbial film attachment, fast startup, fast reproduction speed, good thermal insulation performance, and high oxygen transmission efficiency, and has a significant effect in energy saving and consumption reduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a micro-aerated biochemical filter for wastewater treatment provided by the present invention.

Among them: 1-drain pipe; 2-backwash water pump; 3-mud collecting hopper; 4-water inlet pump; 5-aerator; 6-first mud discharge pipe; 7-overflow trough; 8-three-phase separator; 9-drain pipe; 10-solid collection trough; 11-second mud discharge pipe; 12-plastic filter layer; 13-volcanic rock filter layer; 14-support layer; 15-aerator; 16-water distributor; 17-outer wall of the trough; 18-inner wall of the trough; 19-filter plate; 20-drain pipe; 21-filter material retaining net; 22-backwash fan; 23-mud discharge pump; 24-heating wire; 25-insulation cotton.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with FIG1 and application examples.

A novel composite filler micro-oxygen aerated biofilter with high efficiency backwashing, the filter is connected and composed of a water inlet system, a micro-oxygen aerated biofilter body, an aeration system, a backwashing system, a filter layer area, a three-phase separator, and a solid collection tank, wherein the filter device includes a mud collecting hopper, a supporting layer, a volcanic rock filter layer, a plastic filter layer, an upper clear water area, a solid collection tank, a three-phase separator, and an overflow tank from bottom to top. A water distributor and an aerator are connected to the bottom of the micro-oxygen aerated biofilter device, and a mud discharge pipe and a mud discharge valve are provided at the solid collection tank. In the present invention, the filter is operated in an upflow water inlet mode. Sewage enters the filter from the water distributor, and the water quality is evenly mixed under the action of aeration. Solid suspended matter, ammonia nitrogen, COD and other substances in the sewage are purified through the physical adsorption, biological flocculation and filtration of the filter layer, and finally the clean water flows out from the overflow tank and is discharged through the drain pipe 9. This filter has high adsorption efficiency, small resistance, fast flow rate, short film hanging time, and gives full play to the combined effect of the filtration effect of the micro-aerobic aeration biochemical low-carbon filter and biological adsorption.

In the present invention, it is only necessary to introduce sludge strains at the beginning of establishing the biochemical filter, and then only the excess sludge needs to be discharged from the sludge pipe above the filter layer and the emptying pipe at the bottom of the filter. The three-phase separator is, for example, an inverted funnel shape, and the air generated by aeration or the air from the backwashing fan 22 during backwashing is discharged through the pipe at the top of the three-phase separator. During filtration, the valve on the sewage pipe 20 is closed, and the clean water below the three-phase separator enters the overflow tank 7 upward through the water flow channel, and then is discharged to the outside of the biochemical filter through the drainage pipe 9; and during the backwashing process, the valve on the sewage pipe 20 is opened, and the sludge below the three-phase separator falls into the solid collection tank 10, and then is discharged to the outside of the biochemical filter through the first sludge pipe 6 and the second sludge pipe 11, and the dirty water is discharged to the outside of the biochemical filter from the sewage pipe 20. During the backwashing process of the present invention, the sludge and dirty water are separated by solid and liquid and then discharged from the biochemical filter, so that the dirt after backwashing can be prevented from being discharged to the outside of the biochemical filter in a timely and smooth manner. In the present invention, the three-phase separator is fixed on the side wall of the filter tank body by using a rib structure, for example.

The filter layers of the micro-oxygen aerated biofilter include a plastic filter layer and a volcanic rock filter layer, with the plastic filter layer on top and the volcanic rock filter layer on the bottom. The thickness of the plastic filter layer is 400mm-800mm, the thickness of the volcanic rock layer is 600-1200mm, and the total bed thickness is 1000-2000mm. The bottom layer is a filter material support layer paved with pebbles.

The diameter of the spherical plastic particles in the plastic filter layer is between 20-30 mm, the density is slightly greater than that of water, the density is between 1.1-1.3 g/cm ³ , and the porosity is 50%-70%; the particle diameter of the volcanic rock filter layer is between 30-50 mm, the density is between 1.5-1.8 g/cm ³ , and the porosity is 60%-80%; the supporting layer in the filter tank is pebbles, the particle size is between 20-30 mm, and the density is between 2.3-2.6 g/cm ³ .

The filter material retaining net 21 is set at a height of 200 to 400 mm above the plastic filter layer 12. It is made of stainless steel SS304 and has a triangular mesh structure that can effectively block spherical plastic fillers and prevent the plastic fillers from accumulating at the retaining net to affect water flow. The filter material retaining net 21 effectively intercepts plastic particles while fully ensuring smooth water flow of sewage in the filter layer. The stainless steel material is durable and not easily deformed.

Preferably, a heating wire insulation layer is provided around the filter tank, the heating wire is wrapped around the device and then wrapped with insulation cotton. When the sewage temperature is lower than 10°C, the heating wire is turned on; when the sewage temperature is higher than 15°C, the heating of the sewage is turned off.

The specific principle of improving backwashing efficiency and reducing energy consumption in the present invention is: during the long-term operation of the filter tank, when large particles are trapped by the filter layer, the detached biofilm is blocked in the gap between the filter materials, so that the amount of water in the filter tank gradually decreases, and even blockage occurs, and sewage and oxygen cannot pass through the filter layer smoothly. At this time, close the water inlet, stop the entry of sewage, open the drain valve on the bottom drain pipe, and drain the water in the filter tank first; when the sewage in the filter tank is drained, close the drain valve, open the backwash water pump, pass the backwash water, and increase the air distribution volume of the backwash fan. Since the density of the selected filter material (plastic filter material and volcanic rock filter material) is slightly larger than that of water, the filter material is slightly lifted in the filter tank under the action of gas and water co-flow, and the air distribution volume is maintained for backwashing. Compared with the traditional process method, the present invention can greatly reduce the energy consumed during air distribution and achieve the purpose of energy saving. When the liquid level rises to the bottom of the three-phase separator, the mud discharge valve set at the solid collection tank and located on the first mud discharge pipe 6 and the second mud discharge pipe 11 is opened. Using the gas, solid and liquid three-phase separation principle of the three-phase separator, the gas is discharged from the top through the air guide pipe set at the upper end, and the liquid slowly rises from the surrounding liquid passage and is discharged from the sewage pipe. The solid matter or sludge is settled in the solid collection tank through the diversion effect of the conical baffle of the three-phase separator, and then discharged from the filter tank through the mud discharge valve. When the air distribution is stopped, some larger blocks trapped at the bottom of the filter layer and the biofilm and particulate matter detached from the gap of the filter material are freely settled in the mud collection bucket 3 at the bottom through sedimentation. The emptying valve on the emptying pipe 1 is opened to discharge the sludge cleanly, so as to achieve the purpose of emptying the sludge, preventing accumulation and improving the backwashing efficiency.

Compared with the traditional micro-oxygen aerated biochemical filter, the micro-oxygen aerated biochemical filter of the present invention uses a combination of plastic filter material and volcanic rock filter material, both of which have a slightly higher density than water, and there is a density difference between the two. No large backwashing air volume is required. When the airflow slightly lifts the two filter materials, the two filter materials are lifted to different heights, so that the biofilm and large particles detached between different filter materials and between the same filter materials can be washed out. Moreover, due to the characteristics of the two filter materials such as specific surface area, surface smoothness, and porosity, the microbial population structure formed in the two filter layers is significantly different, which enhances the biofilm's ability to purify sewage and its ability to resist shock loads.

In the present invention, a water distributor and an aerator are arranged between the filter layer and the mud collecting bucket, and a filter plate is used to separate the upper filter layer and the lower water distributor and aerator. The diameter of the filter plate is the same as the inner diameter of the filter tank, and the diameter of the perforations arranged in the filter plate is, for example, 5 mm, evenly distributed, and the gap between the holes is, for example, 2.5 mm, which can prevent the filter material from passing through the filter plate and entering the mud collecting bucket, and at the same time will not reduce the oxygen transfer efficiency and water flow rate. The water distributor 16 can be arranged in an annular manner on the pipe wall of the filter tank, and the water outlet is arranged at a certain interval. The aerator 15 can be composed of two concentric annular tubes, and a plurality of aeration holes are evenly arranged on the annular tubes, and a microporous aeration disk can also be arranged on the aeration hole. The water distributor is arranged below the aerator, for example, 20 cm below it, so that the incoming water can achieve uniform mixing of water quality under the action of aeration.

The bottom of the present invention is a mud collecting bucket 3, which is used to collect the intercepted blocks and settled sludge during normal water inlet filtration and backwashing stage, and discharge these debris from the filter tank through the emptying pipe at the bottom.

The biochemical filter of the present invention can also be used to treat urban domestic sewage, rural domestic sewage, etc.

The method for performing efficient backwashing and reducing energy consumption by using the device comprises the following steps:

1) When the micro-oxygen aerated biochemical low-carbon filter tank is clogged during the rising process of water flow, turn off the water inlet pump 4 to stop the water inlet. Open the drain pipe 1 at the bottom to drain the original sewage in the filter tank.

2) When the sewage in the filter tank is drained, close the drain pipe 1, turn on the backwash water pump 2, introduce backwash water, and turn on the backwash fan 22. When the filter material appears to be slightly lifted, due to the inconsistent density of the two filter materials, the lifted height is also inconsistent, and some large particles and detached biofilms are washed out.

3) When the liquid level rises to contact the bottom of the three-phase separator 8, open the mud discharge valves on the mud discharge pipes 6 and 11. Using the gas, solid and liquid three-phase separation principle of the three-phase separator 8, the gas is discharged from the top through the air guide pipe arranged at the upper end, and the liquid slowly rises from the surrounding space and is discharged from the sewage pipe 20. The solid matter or sludge is settled in the solid collection tank 10 through the diversion effect of the conical baffle of the three-phase separator 8, and then discharged from the filter tank through the mud discharge valve.

During the backwashing stage of stopping air distribution, some larger blocks trapped at the bottom of the filter layer and biofilms and particles detached from the gaps in the filter material settle freely in the mud collecting bucket 3 at the bottom through sedimentation. The mud pump 23 and the drain valve on the drain pipe 1 are opened to drain them out.

A heating wire insulation layer is set on the side wall of the device, which is wrapped with heating wire and then wrapped with insulation cotton. When the sewage water temperature is lower than 10℃, the heating wire heating is turned on. When the sewage water temperature is higher than 15℃, the heating wire heating is turned off.

In the present invention, ① the upper and lower filter materials have different particle sizes and densities, which can better intercept pollutants such as suspended matter, impurities and bacteria in the water, and improve the filtering effect; ② the plastic filter material particles are finer, which can better filter fine particles in the water; the lower volcanic rock layer filter material particles are coarser, which can better intercept large particles. This combination can extend the service life of the filter material, reduce the number of replacements and maintenance costs; ③ because the particle sizes and densities of the plastic particles and volcanic rock particles of the upper and lower filter materials are different, a certain gap is formed between the layers, making the water flow more smoothly and not easy to be blocked, thereby improving the water flow efficiency; the design of double-layer different filter materials can also reduce backwashing time and water consumption, reduce energy consumption and cost.

In the biochemical filter, in the presence of oxygen, the organic matter in the wastewater is adsorbed, oxidized and reduced by the microorganisms in the microbial film that adheres to the filler, and the complex macromolecular organic matter is oxidized and decomposed into simple inorganic matter, thereby achieving the purpose of purifying the wastewater. The biochemical filter will also nitrify the ammonia nitrogen in the wastewater, converting NH ₃ -N into NO ₃ -N or NO ₂ -N, thereby ultimately achieving the removal of ammonia nitrogen.

When the biochemical filter is in operation, the aeration volume supplied by the aerator (5) and the dissolved oxygen concentration in the biochemical filter should be properly regulated, the hydraulic load, backwashing cycle and the amount of biofilm in the filter should be properly adjusted, and the transparency of the supernatant in the filter, the color, state and odor of the biofilm on the surface of the filter material, etc. should be observed in time. When the water temperature of the biochemical filter is low, heating wire should be used for heating, and/or the method of appropriately extending the aeration time and reducing the hydraulic load should be adopted to ensure the treatment effect. If the influent water lacks nutrients and affects the metabolism of the microorganisms in the biofilm, nutrients can be added to the pool according to the situation of the biofilm, for example, nutrient sources can be added at a ratio of _BOD5 :N:P=100:5:1. The N source is urea, and the P source is sodium phosphate or disodium hydrogen phosphate. When the microbial film in the biochemical filter grows too fast, resulting in too thick a biofilm or too much suspended matter trapped in the filter layer, affecting the normal quality of the treated water, the filter needs to be backwashed.

The backwashing process of the biochemical filter usually adopts three steps of "air washing → air-water combined backwashing → water rinsing".

1) Air washing

Close the water inlet pump 4 → close the aerator 5 → close the aeration valve → open the drain pipe 1 and the sludge pump 23 to drain the sewage → close the drain pipe 1 and the sludge pump 23 → open the sewage pipe 20 → open the air inlet valve on the backwash fan 22 → open the backwash fan 22 → perform air washing. Under the shearing effect of the air flow and the friction between the filter materials, the impurities and aged biofilm on the filter material surface fall off; the main purpose of air washing is to loosen the filter material layer and expand the filter material layer. The air washing intensity is generally 12 to 20L/( ^m2 ·s). The backwashing time is generally 7 minutes.

2) Combined air and water backwashing

While air washing, open the water valve on the backwash water pump 2 → start the backwash water pump 2 → perform air-water combined backwashing, and the backwash water enters the filter tank to further wash the filter material. The main purpose of air-water combined backwashing is to wash away the suspended matter and aged microbial membrane trapped on the filter material.

When the biochemical filter uses air-water combined backwashing, the air and water intensity of the backwashing should be appropriate, and the air washing intensity is generally 12-20L/(m ² ·s). The air speed of the backwashing is generally 70-100m ³ /h, the water washing intensity of the backwashing is generally 6.0-10L/(m ² ·s), and the flushing time is generally controlled at 7-22min. The backwashing time can also be adjusted according to the specific situation.

3) Water rinsing

Stop the backwash fan 22 → close the air inlet valve on the backwash fan → stop air washing, rinse with water alone, and flush the impurities in the water into the solid collection tank 10, the sewage pipe 20 or the mud collection bucket 3. The main purpose of water rinsing is to flush the suspended matter and aged microbial membrane on the surface of the filter material out of the biochemical filter tank. The time is generally 6 to 10 minutes.

In general, the present invention relates to a micro-oxygen aerated biochemical filter for wastewater treatment and a wastewater treatment method and backwashing method thereof. The density of the two selected filter materials (plastic filter material and volcanic rock filter material) is slightly greater than that of water. Under the action of gas-water co-flow, the filter material is slightly lifted in the filter tank, thereby greatly reducing the energy consumed during air distribution and achieving the purpose of energy saving. When aeration and air distribution are stopped, some larger blocks trapped at the bottom of the filter layer and the biofilm and particulate matter detached from the gaps in the filter material are freely settled in the mud collecting bucket through sedimentation. The mud discharge valve and mud discharge pump 23 on the emptying pipe 1 are opened to discharge the mud cleanly, thereby achieving the purpose of emptying the sludge, preventing accumulation and improving the backwashing efficiency. The porous structure of the two filter materials can provide a place for enrichment and heat preservation for microorganisms, and the heating of the heating wire on the outer wall of the filter tank can provide sufficient heat for wastewater treatment and ensure the treatment activity of microorganisms.

That is to say, the biochemical filter provided by the present invention integrates filler retention and biological adsorption, and has the characteristics of large biofilm surface area, good microbial attachment effect, high activity, high adsorption efficiency and small resistance, fast flow rate and short film hanging time. It gives full play to the combined effect of the filtration effect and biological adsorption of the micro-aerobic aeration biochemical filter, and at the same time makes up for the shortcomings of the existing biochemical filter, such as incomplete backwashing, poor sewage discharge, high energy consumption and low microbial activity at low temperature.

The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims (7)

1. A micro-oxygen aerated biochemical filter for wastewater treatment, characterized in that the biochemical filter is used for treating tunnel construction wastewater, the biochemical filter comprises a mud collecting bucket (3) arranged at the bottom and a cylindrical filter body arranged above the mud collecting bucket (3), in which a water distributor (16), an aerator (15), an air distribution pipe, a filter plate (19), a supporting layer (14), a volcanic rock filter layer (13), a plastic filter layer (12), a filter material retaining net (21), a solids collection tank (10) and a three-phase separator (8) are arranged from bottom to top, and the three-phase separator The top of the device (8) extends above the highest position of the liquid level in the biochemical filter and is used to discharge the separated gas to the outside of the biochemical filter. The outer wall (17) of the solid collection tank (10) is the inner wall of the filter body or the outer wall and the inner wall of the filter body are overlapped, and the inner wall (18) of the solid collection tank (10) is a truncated cone with a shorter diameter at the top and a longer diameter at the bottom. A tank bottom plate is arranged between the outer wall (17) and the inner wall (18), and a mud discharge port and a mud discharge pipe are arranged above the bottom plate and on the side wall of the filter body. The three-phase separator (8) The solid-liquid separation section is located at the bottom and has a conical structure. A water flow channel for clean water and dirty water to pass through is formed between the bottom edge of the three-phase separator (8) and the inner wall of the filter tank body. A sewage pipe (20) for discharging dirty water generated during backwashing and an overflow trough (7) for discharging clean water generated during wastewater treatment are arranged in sequence from bottom to top above the bottom edge of the three-phase separator (8) and on the side wall of the filter tank body. A drainage pipe (9) and a drainage valve for discharging clean water are arranged at the bottom of the overflow trough (7). The water distributor (16) is connected to a drain valve arranged on the filter tank body. The invention relates to a filter tank having a filter element and a filter element. The filter element is connected to a water inlet pump (4) outside the filter tank body, the aerator (15) is connected to an aerator (5) arranged outside the filter tank body, and the air distribution pipe is connected to a backwash fan (22) arranged outside the filter tank body; an emptying pipe (1) and a mud pump (23) arranged on the emptying pipe (1), as well as a backwashing water pipe and a backwashing water pump (2) connected to the emptying pipe (1) are arranged at the bottom of the mud collecting hopper (3); the height of the volcanic rock filter layer (13) is 0.6-1.2 m, the diameter of the particles therein is 3-5 cm, the density is 1.5-1.8 g/cm ³ , and the porosity is 60%-80%; the height of the plastic filter layer (12) is 0.4-0.8 m, the diameter of the spherical plastic particles therein is 2-3 cm, the density is 1.1-1.3 g/cm ³ , and the porosity is 50%-70%. 2. The micro-aerobic aerated biofilter according to claim 1, characterized in that the mud discharge pipe comprises a first mud discharge pipe (6) and a second mud discharge pipe (11) which are symmetrically arranged. 3. The micro-aerobic aerated biochemical filter according to claim 1 is characterized in that a thermal insulation layer is provided on the outer wall of the filter body, the heating wire (24) is wrapped by thermal insulation cotton (25) to form the thermal insulation layer, and tin foil for decoration and wrapping is provided on the outer side of the thermal insulation layer. 4. The micro-aerobic aerated biofilter according to claim 1 is characterized in that the bottom height of the three-phase separator (8) is higher than the top height of the solid collection tank (10), and the top of the three-phase separator (8) is a circular pipe for exhaust. 5. The micro-aerobic aerated biofilter according to any one of claims 1 to 4, characterized in that the supporting layer (14) is a pebble layer, wherein the particle diameter is 2 to 3 cm and the density is 2.3 to 2.6 g/ ^cm3 . 6. The micro-oxygen aerated biofilter according to any one of claims 1 to 4, characterized in that the filter material retaining net (21) is arranged 20 to 40 cm above the plastic filter layer (12). 7. The micro-aerobic aerated biofilter according to claim 6, characterized in that the filter material retaining net (21) is a triangular mesh retaining net of stainless steel.