CN218968975U - Biological filter - Google Patents

Abstract

The application relates to a biological filter, which comprises a water inlet tank, a filter tank and a clean water tank, wherein the filter tank is respectively communicated with the water inlet tank and the clean water tank, the biological filter further comprises a filter assembly and a back flushing assembly, the filter assembly is positioned in the filter tank and comprises a first filter plate, a second filter plate and a sponge filter layer, the first filter plate is arranged at intervals with the bottom of the filter tank, the second filter plate is positioned on one surface of the first filter plate far away from the bottom of the filter tank, and the second filter plate is arranged at intervals with the first filter plate so as to place the sponge filter layer; the back flush assembly comprises a first pipe, a second pipe and a flushing pump, wherein the first pipe is used for connecting the bottom of the water inlet tank with the bottom of the filter tank, the second pipe is used for connecting the bottom of the clean water tank with the bottom of the clean water tank, and the flushing pump is connected with the first pipe and the second pipe. The water head loss can be reduced through the arrangement of the filtering component and the back flushing component, the phenomenon of filler agglomeration and blockage is avoided, and the later filtering treatment capacity and efficiency are not affected.

Description

Biological filter

Technical Field

The application relates to the technical field of sewage treatment, in particular to a biological filter.

Background

The biological aerated filter is a novel sewage treatment process developed based on the common biological aerated filter in the 80 th to 90 th century by referring to the technology principle of the water-feeding filter, is a modified form of the common biological aerated filter, and can be also regarded as a special form of a biological contact oxidation method, namely, a bioreactor is filled with particle fillers with high specific surface area so as to provide carriers for microorganism growth, the sewage flows through a filler layer from top to bottom or from top to bottom according to different water inlet and outlet directions, oxygen required by biochemical reaction is provided by blast aeration at the lower part of the filler layer, and organic pollutants in the sewage are purified under the action of microorganisms attached to the surface of the filler, and meanwhile, the fillers play a role in physical filtration.

The biological aerated filter generally adopts quartz sand filler, and after long-term use, the biological aerated filter has larger head loss, poor film forming effect and low biochemical treatment efficiency; meanwhile, the back flushing of the aeration biological filter is one of key factors for determining the operation of the filter, the existing biological filter cannot effectively perform back flushing, and filler agglomeration blocking phenomenon easily occurs, so that the later filtering treatment capacity and efficiency are reduced.

Disclosure of Invention

The utility model provides an aim at provides a biological filter, this biological filter accessible filter element and back flush subassembly set up the loss that reduces the head, avoid filler reunion to block up the phenomenon to take place, do not influence later stage filtration treatment ability and efficiency.

To this end, this application embodiment provides a biological filter, including inlet tank, filtering ponds and clean water basin, the filtering ponds respectively with inlet tank, clean water basin intercommunication, the biological filter still includes: the filter assembly is positioned in the filter tank and comprises a first filter plate, a second filter plate and a sponge filter layer, wherein the first filter plate and the bottom of the filter tank are arranged at intervals, the second filter plate is positioned on one surface of the first filter plate far away from the bottom of the filter tank, and the second filter plate and the first filter plate are arranged at intervals so as to place the sponge filter layer; the back flush assembly comprises a first pipe, a second pipe and a flushing pump, wherein the first pipe is used for connecting the bottom of the water inlet tank with the bottom of the filter tank, the second pipe is used for connecting the bottom of the clean water tank with the bottom of the clean water tank, and the flushing pump is connected with the first pipe and the second pipe.

In one possible implementation, the device further includes a gas distribution assembly, the gas distribution assembly including: the air distribution pipe is arranged between the first filter plate and the bottom of the filter tank and is provided with a plurality of air distribution holes; the power piece is connected with the gas distribution pipe and provides gas for the gas distribution pipe.

In one possible implementation, the backwash assembly further includes an overflow pipe and a wastewater tank, one end of the overflow pipe extends into an upper end of the filter tank, and the other end of the overflow pipe is connected with the wastewater tank.

In one possible implementation, the backwash assembly further includes a sludge discharge pipe having one end extending into the lower end of the filter tank and the other end connected to the wastewater tank.

In one possible implementation, the device further comprises a liquid level meter, wherein the liquid level meter is arranged in the water inlet tank, and the liquid level meter is electrically connected with the flushing pump.

In one possible implementation manner, the filter further comprises a water inlet pipe, the water inlet pipe connects the bottom of the water inlet tank with the bottom of the filter tank, an overflow port is arranged at one end, away from the first filter plate, of the filter tank, and the filter tank is communicated with the clean water tank through the overflow port.

In one possible implementation, the separation distance between the first filter plate and the bottom of the filter tank is 350mm-450mm.

In one possible implementation, the second filter plate is spaced from the overflow outlet by a distance of 150mm to 250mm.

In one possible implementation, the separation distance between the first and second filter plates is 1m-2m.

In one possible implementation, the distance between the air distribution pipe and the first filter plate is 80-120 mm.

According to the biological filter provided by the embodiment of the application, the biological filter comprises a water inlet tank, a filter tank and a clean water tank, wherein the filter tank is respectively communicated with the water inlet tank and the clean water tank, the biological filter further comprises a filter assembly and a back flushing assembly, the filter assembly is positioned in the filter tank and comprises a first filter plate, a second filter plate and a sponge filter layer, the first filter plate is arranged at intervals with the bottom of the filter tank, the second filter plate is positioned on one surface of the first filter plate away from the bottom of the filter tank, and the second filter plate is arranged at intervals with the first filter plate so as to place the sponge filter layer; the back flush assembly comprises a first pipe, a second pipe and a flushing pump, wherein the first pipe is used for connecting the bottom of the water inlet tank with the bottom of the filter tank, the second pipe is used for connecting the bottom of the clean water tank with the bottom of the clean water tank, and the flushing pump is connected with the first pipe and the second pipe. During back flushing, the sewage in the water inlet tank is pumped into the filter tank by a flushing pump for preliminary cleaning, and pollutants in the sponge filter layer are preliminarily flushed out of the filter assembly; and then the clean water in the clean water tank is pumped into the filter tank by the flushing pump for secondary flushing, pollutants in the sponge filter layer are further flushed out of the filter assembly, the sewage in the water inlet tank is selected for primary flushing, the using amount of the clean water is saved, the head loss of the water inlet tank can be reduced, and the flushing effect of the filter tank can be improved by selecting the clean water in the clean water tank during secondary flushing. The sponge filter layer is arranged, so that the phenomenon of agglomeration and blockage of the filler layer is avoided in the back flushing process.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description will be given below of the drawings that are needed in the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art. In addition, in the drawings, like parts are designated with like reference numerals and the drawings are not drawn to actual scale.

FIG. 1 shows a top view of a biological filter provided in an embodiment of the present application;

fig. 2 shows a schematic structural diagram of a biological filter according to an embodiment of the present application.

Reference numerals illustrate:

1. a water inlet tank; 2. a filtering tank; 21. an overflow port; 3. a clean water tank; 4. a filter assembly; 41. a first filter plate; 42. a second filter plate; 43. a sponge filter layer; 5. a back flushing assembly; 51. a first tube; 52. a second tube; 53. a flushing pump; 54. an overflow pipe; 55. a mud pipe; 6. a gas distribution assembly; 61. an air distribution pipe; 62. a power member; 7. a liquid level gauge; 8. a water inlet pipe.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

Fig. 1 shows a top view of a biological filter provided in an embodiment of the present application, and fig. 2 shows a schematic structural diagram of a biological filter provided in an embodiment of the present application. Wherein the arrow direction is the water flow direction.

As shown in fig. 1 to 2, the embodiment of the application provides a biological filter, which comprises a water inlet tank 1, a filter tank 2 and a clean water tank 3, wherein the filter tank 2 is respectively communicated with the water inlet tank 1 and the clean water tank 3. When in use, sewage firstly enters the water inlet tank 1, then flows into the filter tank 2 through the water inlet tank 1 for filtering, and filtered clear water enters the clear water tank 3 from the filter tank 2 for temporary storage so as to facilitate subsequent discharge.

There is no limitation on the location where sewage enters the intake tank 1, for example, sewage may enter the intake tank 1 from the upper end, the middle portion, or the lower portion of the intake tank 1. Without limiting the location where the wastewater enters the filter tank 2 from the influent tank 1, for example, the wastewater may enter the filter tank 2 from below the influent tank 1, the wastewater may enter the filter tank 2 from above the influent tank 1, and the wastewater may enter the filter tank 2 from above the influent tank 1. Without limiting the position of the clean water entering the clean water tank 3, the clean water can enter the clean water tank 3 from the lower part of the filter tank 2, the clean water can enter the clean water tank 3 from the upper part of the filter tank 2, and the clean water can enter the clean water tank 3 from the upper part of the filter tank 2.

The biological filter further comprises a filter assembly 4 and a back flushing assembly 5, the filter assembly 4 is located in the filter tank 2, the filter assembly 4 comprises a first filter orifice 41, a second filter orifice 42 and a sponge filter layer 43, the first filter orifice 41 is arranged at intervals with the bottom of the filter tank 2, the second filter orifice 42 is located on one face, far away from the bottom of the filter tank 2, of the first filter orifice 41, and the second filter orifice 42 is arranged at intervals with the first filter orifice 41 to place the sponge filter layer 43. The backwash assembly 5 includes a first pipe 51 connecting the bottom of the influent tank 1 with the bottom of the filtration tank 2, a second pipe 52 connecting the bottom of the clean water tank 3 with the bottom of the clean water tank 3, and a rinse pump 53 connected with the first pipe 51 and the second pipe 52.

Wherein, the setting of second filter plate 42 and first filter plate 41 interval set up for sponge filter layer 43 provides the space, and this application does not do not limit to the quantity of first filter plate 41, second filter plate 42. The sponge filter layer 43 is made of polyurethane sponge, compared with the conventional quartz sand filler, the sponge filter layer 43 has good film forming effect, can be used for biological degradation and nitrification and denitrification of a biological film on the surface of a filter material, has high biochemical treatment efficiency and small head loss, is not easy to block in operation, can absorb organic matters through facultative or aerobic microorganism growth and metabolism on the filler, and can effectively increase the effect of purifying pollutants such as COD, SS, ammonia nitrogen, total nitrogen and the like. During filtration, the sewage can flow into the sponge filter layer 43 from the first filter plate 41, then flow out of the second filter plate 42 and then flow into the clean water tank 3. Or, the sewage flows into the sponge filter layer 43 from the second filter plate 42, then flows out of the first filter plate 41, and then enters the clean water tank 3.

The back flushing assembly 5 includes a first pipe 51 and a flushing pump 53, both ends of the first pipe 51 are connected to the bottom of the water intake tank 1 and the bottom of the filter tank 2, respectively, and the first pipe 51 is also connected to the flushing pump 53. During back flushing, the flushing pump 53 can pump water in the bottom of the water inlet tank 1 to the bottom of the filter tank 2 through the first pipe 51, the water flows upwards from the bottom of the filter tank 2 to perform back flushing, the flushing pump 53 can be adjusted to control the flow rate of the back flushed water, thereby controlling the flushing effect of the water on the filter assembly 4 and simultaneously reducing the head loss of the water passing through the water inlet tank 1. Compared with the water pumping of the water inlet tank 1 from the upper end of the water inlet tank 1, the first pipe 51 is connected with the bottom of the water inlet tank 1, so that water flow is facilitated, the flushing pump 53 is facilitated, and the energy consumption of the flushing pump 53 is reduced.

The back flushing assembly 5 further comprises a second pipe 52, one end of the second pipe 52 is connected with the bottom of the clean water tank 3, the other end of the second pipe 52 is connected with the bottom of the filter tank 2, the second pipe 52 is further connected with a flushing pump 53, after the flushing pump 53 pumps water in the water inlet tank 1 to the bottom of the filter tank 2 to perform primary cleaning on the filter tank 2, the flushing pump 53 pumps water from the clean water tank 3 to the bottom of the filter tank 2 to perform secondary cleaning on the filter tank 2, and the flow rate of the back flushing water can be adjusted to control the flow rate of the back flushing water, so that the flushing effect of the water on the filter assembly 4 is controlled. Compared with the water pumping of the clean water tank 3 from the upper end of the water inlet tank 1, the second pipe 52 is connected with the bottom of the clean water tank 3, so that water flow is facilitated, the flushing pump 53 is facilitated to pump water, and the energy consumption of the flushing pump 53 is reduced.

During back flushing, the sewage in the water inlet tank 1 is pumped into the filter tank 2 through the first pipe 51 by the flushing pump 53 for preliminary cleaning, and the preliminary flushing time can be 5min, 10min and other flushing time, so that pollutants in the sponge filter layer 43 are preliminarily flushed out of the filter assembly 4, suspended matters are positioned below the filter assembly 4, and sediments are positioned below the filter assembly 4; and then the clean water in the clean water tank 3 is pumped into the filter tank 2 through the second pipe 52 by the flushing pump 53 for secondary flushing, wherein the secondary flushing time can be 5min, 10min, 15min and the like, and pollutants in the sponge filter layer 43 are further flushed out of the filter assembly 4, so that the pollution-receiving rate of the sponge filter layer 43 is improved. The sewage of the water inlet tank 1 is selected for primary flushing, so that the consumption of clean water is saved, the head loss of the water inlet tank 1 can be reduced, and the clean water of the clean water tank 3 is selected for secondary flushing, so that the flushing effect of the filter tank 2 can be improved. The sponge filter layer 43 is arranged, so that the phenomenon of agglomeration and blockage of the filler layer is avoided in the back flushing process; and the first filter plate 41 and the bottom of the filter tank 2 are arranged at intervals, so that the flushing pump 53 can be prevented from directly flushing sewage or clean water to the sponge filter layer 43 during back flushing, the damage of the sponge filter layer 43 is reduced, and the filtering effect of the filter tank 2 is further improved.

In some alternative embodiments, the biological filter further comprises a gas distribution assembly 6, the gas distribution assembly 6 comprises a gas distribution pipe 61 and a power piece 62, the gas distribution pipe 61 is arranged between the first filter orifice 41 and the bottom of the filter tank 2, and the gas distribution pipe 61 is provided with a plurality of gas distribution holes; the power member 62 is connected to the gas distribution pipe 61 and supplies gas to the gas distribution pipe 61.

The gas distribution assembly 6 is a perforated aeration device, the gas distribution pipe 61 is a microporous pipe connected in an annular mode, the gas distribution pipe 61 is located below the first filter plate 41, the gas distribution pipe 61 is communicated with the power piece 62, and the power piece 62 is a device capable of emitting gas, such as a fan. The micropores of the gas distribution pipe 61 are provided with a plurality of micropores, and the micropores can be distributed around the gas distribution pipe 61, so that the gas distribution pipe 61 is uniform in gas outlet.

When in use, the power piece 62 conveys gas to the gas distribution pipe 61, and the gas of the gas distribution pipe 61 is conveyed to the sponge filter layer 43 to provide oxygen for the sponge filter layer 43, so that the filtering effect of the sponge filter layer 43 on pollutants such as COD, SS, ammonia nitrogen, total nitrogen and the like is improved. During back flushing, the power piece 62 can be started, so that the air distribution pipe 61 is matched with the first pipe 51 or the second pipe 52, the back flushing air quantity is increased by adjusting the working frequency of the power piece 62, the back flushing direction is the same-direction flow of air and water, the same-direction flow can promote uniform air distribution and water distribution, the SS trapped at the bottom can be brought into the middle upper part of the filter tank 2 in the rising process of air bubbles, the dirt receiving rate of the sponge filter layer 43 is increased, the back flushing interval time is prolonged, the oxygen transmission and utilization are facilitated, and the back flushing effect is improved.

In some alternative embodiments, backwash assembly 5 further includes overflow pipe 54 and a wastewater tank, one end of overflow pipe 54 extending into the upper end of filter tank 2 and the other end of overflow pipe 54 being connected to the wastewater tank. When the first pipe 51 or the second pipe 52 backflushes the filtering tank 2, or after flushing, the overflow pipe 54 may suck the liquid of the upper layer of the filtering tank 2 into the wastewater tank, thereby avoiding secondary pollution of the filtering tank 2 by suspended matters.

In some alternative embodiments, backwash assembly 5 further includes a sludge discharge pipe 55 with one end of sludge discharge pipe 55 extending into the lower end of filter tank 2 and the other end of sludge discharge pipe 55 being connected to the wastewater tank. When the first pipe 51 or the second pipe 52 backflushes the filter tank 2, or after flushing, the sludge discharge pipe 55 can pump the sludge at the lower layer of the filter tank 2 into the wastewater tank, thereby avoiding secondary pollution of the filter tank 2 by the sludge.

In some alternative embodiments, the device further comprises a liquid level meter 7, wherein the liquid level meter 7 is arranged on the water inlet tank 1, and the liquid level meter 7 is electrically connected with the flushing pump 53. The liquid level meter 7 is arranged in the water inlet tank 1, and when the sewage in the water inlet tank 1 reaches the set scalar, the water head loss of the water inlet tank 1 flowing to the filter tank 2 is larger. At this time, the flushing pump 53 is started to suck the water in the water intake tank 1, reduce the head loss of the water intake tank 1 flowing to the filter tank 2, and simultaneously clean the filter tank 2, thereby improving the dirt receiving rate of the sponge filter layer 43.

In some alternative embodiments, a timer may be provided, electrically connected to the flushing pump 53, and the operator may set the timer, and after a certain time interval, the flushing pump 53 is activated to back flush the filter tank 2.

In some alternative embodiments, the filter tank further comprises a water inlet pipe 8, the water inlet pipe 8 connects the bottom of the water inlet tank 1 with the bottom of the filter tank 2, one end of the filter tank 2 away from the first filter orifice plate 41 is provided with an overflow port 21, and the filter tank 2 is communicated with the clean water tank 3 through the overflow port 21.

The bottom of the water inlet tank 1 is connected with the bottom of the filter tank 2 through the water inlet pipe 8, and when the sewage treatment device works, sewage flows into the filter tank 2 from the bottom of the water inlet tank 1 through the water inlet pipe 8 by means of self gravity, so that a water pump is not required to be additionally arranged, the running cost of the system is saved, and the running cost of the system is saved. The filter tank 2 is communicated with the clean water tank 3 through the overflow port 21, namely sewage flows from bottom to top, overflows from the overflow port 21 after purification, and the flow speed of water is gentle, so that the scouring of the sewage flow to the sponge filter layer 43 can be reduced, the microbial flora is reduced to be separated from the filter tank 2, and the water purifying effect of the filter tank 2 is facilitated.

The overflow port 21 is located at a position 200mm above the first filter plate 41, so that clear water flows to the overflow port 21 for a certain distance, and clear water is convenient to further precipitate, and the filtering effect of the filtering component 4 is improved.

Further, the first pipe 51, the second pipe 52, the overflow pipe 54, the water inlet pipe 8 and other pipes can be provided with electric valves so as to be convenient for an operator to control.

In some alternative embodiments, the separation distance between first filter plate 41 and the bottom of filter tank 2 is 350mm-450mm. The interval between the first filter plate 41 and the bottom of the filter tank 2 can be 350mm, 400mm or 450mm, and the like, preferably, the interval between the first filter plate 41 and the bottom of the filter tank 2 is 400mm, so that when sewage or clear water flows into the filter tank 2, scouring of the sponge filter layer 43 is reduced, and damage of the sponge filter layer 43 is reduced.

In some alternative embodiments, the first filter plate 41 is spaced from the second filter plate 42 by a distance of 1m-2m. That is, the thickness of the sponge filter layer 43 is 1mm, 1.5mm or 2 mm; when the first filter plate 41 and the second filter plate 42 are spaced by 1m, the filtering effect of the filtering component 4 is poor, and when the first filter plate 41 and the second filter plate 42 are spaced by more than 2mm, the filtering speed of sewage is slow. Therefore, the thickness can not only meet the filtering effect of the filtering component 4 on sewage, but also not influence the sewage filtering speed.

In some alternative embodiments, the spacing distance between the air distribution tube 61 and the first filter plate 41 is 80mm-120mm. The air distribution pipe 61 is spaced 80mm, 90mm, 100mm, 110mm or 120mm from the first filter plate 41, and preferably the air distribution pipe 61 is spaced 100mm from the first filter plate 41. When the interval between the air distribution pipe 61 and the first filter plate 41 is smaller than 80mm, the impact of the air in the air distribution pipe 61 on the sponge filter layer 43 is too large, so that the sponge filter layer 43 is easy to damage, and the effect of air flowing into the sponge filter layer 43 is poor. Therefore, the setting of this distance not only can satisfy the air and get into sponge filter layer 43, improves the filter effect, also improves the life of sponge filter layer 43.

It should be noted that references in the specification to "one embodiment," "an example embodiment," "some embodiments," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It should be readily understood that the terms "on … …", "above … …" and "above … …" in this disclosure should be interpreted in the broadest sense such that "on … …" means not only "directly on something", but also includes "on something" with intermediate features or layers therebetween, and "above … …" or "above … …" includes not only the meaning "on something" or "above" but also the meaning "above something" or "above" without intermediate features or layers therebetween (i.e., directly on something).

Further, spatially relative terms, such as "below," "beneath," "above," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may have other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. The utility model provides a biological filter, includes intake pool, filtering ponds and clean water basin, the filtering ponds respectively with intake pool, clean water basin intercommunication, its characterized in that, biological filter still includes:

the filter assembly is positioned in the filter tank and comprises a first filter plate, a second filter plate and a sponge filter layer, wherein the first filter plate is arranged at intervals with the bottom of the filter tank, the second filter plate is positioned on one surface of the first filter plate far away from the bottom of the filter tank, and the second filter plate is arranged at intervals with the first filter plate so as to place the sponge filter layer;

the back flush assembly comprises a first pipe, a second pipe and a flushing pump, wherein the first pipe is used for connecting the bottom of the water inlet tank with the bottom of the filter tank, the second pipe is used for connecting the bottom of the clean water tank with the bottom of the clean water tank, and the flushing pump is connected with the first pipe and the second pipe.

2. The biofilter of claim 1, further comprising a gas distribution assembly, said gas distribution assembly comprising:

the air distribution pipe is arranged between the first filter plate and the bottom of the filter tank and is provided with a plurality of air distribution holes;

the power piece is connected with the gas distribution pipe and provides gas for the gas distribution pipe.

3. The biofilter of claim 1, wherein said backwash assembly further comprises an overflow pipe and a wastewater tank, one end of said overflow pipe extending into an upper end of said filter tank, the other end of said overflow pipe being connected to said wastewater tank.

4. A biofilter according to claim 3, wherein said backwash assembly further comprises a sludge discharge pipe, one end of said sludge discharge pipe extending into the lower end of said filter tank, the other end of said sludge discharge pipe being connected to said wastewater tank.

5. The biofilter of claim 1, further comprising a level gauge disposed in said influent tank, said level gauge being electrically connected to said rinse pump.

6. The biofilter of claim 1, further comprising a water inlet pipe, wherein the water inlet pipe connects the bottom of the water inlet tank with the bottom of the filter tank, an overflow port is arranged at one end of the filter tank away from the first filter orifice plate, and the filter tank is communicated with the clean water tank through the overflow port.

7. A biological filter according to claim 1, wherein the first filter plate is spaced from the bottom of the filter tank by a distance of 350mm to 450mm.

8. A biofilter according to claim 6, characterised in that the separation distance between said second filter plate and said overflow aperture is 150mm-250mm.

9. A biological filter according to claim 1, wherein the first filter plate is spaced from the second filter plate by a distance of 1m to 2m.

10. A biofilter according to claim 2, characterised in that the distance between said air distribution tube and said first filter plate is 80-120 mm.

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