CN210796170U - A fish pond fish farming and fish manure sewage treatment and recycling system - Google Patents

Abstract

The utility model discloses a circulating water fish culture excrement sewage concentration device and circulating water fish culture excrement concentrating and recycling system, it is connected with the rotary drum to rotate on the frame, it has the drainage hole to distribute on the rotary drum, the rotary drum passes through the motor and drives the rotation, one end of rotary drum is sealed, the other end is open, this open end is the water inlet end, the top of rotary drum is provided with gas blowing device and shower, gas blowing device links to each other with air compressor machine or high-pressure gas pitcher, gas blowing device blows to the rotary drum, the downside of shower is provided with a plurality of water jets or sprinkler heads that spray water towards the rotary drum, the center pin of rotary drum is the hollow shaft, be provided with on the center pin and connect the excrement fill, connect the bottom and the center pin UNICOM of excrement fill, just in time can be located below gas blowing; the excrement in the excrement receiving hopper is discharged from one end of the central shaft, which is far away from the water inlet end. The concentration of the fish manure sewage can be further improved to more than 5 percent, the water consumption is low, the energy consumption of subsequent biochemical treatment is low, and the cost is low.

Description

A fish pond fish farming and fish manure sewage treatment and recycling system

technical field

The utility model relates to a fish pond and fish dung sewage treatment and recycling system, which belongs to the field of water treatment.

Background technique

The density of fish culture in circulating water is high, and the feeding amount of bait is between 1% and 1.2% on average, and a large amount of manure and residual bait will be produced every day. and residual bait, a large amount of sewage is filtered by a microfilter for aerobic treatment, and the treated tail water is used for vegetable cultivation or artificial wetland purification, and finally discharged up to the standard.

Due to the large amount of sewage, high energy consumption in the treatment process, large facility capacity, high construction investment, and large waste of water resources, these problems comprehensively affect the healthy development of circulating water fish farming. Therefore, how to better reduce the energy consumption of aerobic treatment and reduce the treatment cost has become a problem that we need to solve.

Utility model content

In view of the above-mentioned technical problems, the purpose of this utility model is to provide a fish pond fish dung sewage treatment and recycling system, which realizes a closed cycle of planting and breeding, zero discharge of pollutants, symbiosis of aquaponics, good economic benefits, efficient biochemical treatment, and low cost Low.

In order to achieve the above purpose, the technical scheme of the present invention is as follows: a fish pond fish farming and fish dung sewage treatment and recycling system, including a fish pond, the fish dung sewage at the bottom of the fish pond is discharged into a fish dung collection tank, and the middle and upper part of the fish pond A pool surface outlet is provided, which is characterized in that: the pool surface outlet is connected to the microfilter, the clean water from the microfilter enters the ultraviolet disinfection machine for disinfection, and the disinfected water enters the fluidized moving bed biological filter , the water from the fluidized moving bed biological filter is returned to the fish pond, and the backwash water of the microfilter enters the fish manure collection tank;

The sewage in the fish manure collection tank enters the fish manure drum concentrator for concentration, the clean water from the drum concentrator enters the return tank, and the concentrated solution from the fish manure drum concentrator enters the anaerobic fermentation tank, from The water from the anaerobic fermentation tank enters the first aerobic tank, and then enters the sedimentation tank and the biological filter tank in turn, the water from the biological filter tank enters the tail liquid tank, and the water in the tail liquid tank enters the vegetables cultivation system;

The vegetable cultivation system includes a fertilizer pool, a water and fertilizer integrated system, and a vegetable cultivation area. The water pump of the tail liquor pool is pumped into the fertilizer pool, and the effluent of the fertilizer pool enters the water and fertilizer integrated system for nutrient allocation or goes directly to the vegetable cultivation area. The effluent of the integrated water and fertilizer system enters the vegetable cultivation area, and the excess water filtered and purified is recycled through the vegetable cultivation area to return to the return pool;

The water in the return pool enters the second aerobic pool, the outlet of the second aerobic pool is connected with the ultraviolet sterilizer, the outlet of the ultraviolet sterilizer is connected with the filter device, and the water filtered by the filter device returns to the sterilizer. fish pond.

Using the above scheme, there are two ways to collect fish manure sewage. One is that the manure residue in the upper part of the water level of the fish pond enters the microfilter for filtration through the pond surface outlet, and the backwash liquid is discharged into the fish manure collection tank; the other is the fish pond. The manure residue and bait water at the bottom is collected by the manure collector and then discharged to the fish manure collection tank.

After the fecal residue in the upper and middle of the water level of the fish pond is filtered by the microfilter, the clean water enters the ultraviolet disinfection machine to remove the pathogenic microorganisms in the water, including the microbial population lineages such as bacteria, viruses, and fungi that are sensitive to the destructive power of ultraviolet technology. Then enter the fluidized moving bed biological filter to remove harmful substances such as ammonia nitrogen and nitrite. Finally back to the fish pond.

The sewage in the fish manure collection tank enters the fish manure drum concentrator for concentration, and then goes through anaerobic, aerobic, sedimentation, and biological filtration treatments to remove more than 90% of COD _cr and the final BOD ₅ <5mg after reaching the concentration of TS3-5%. /L, the nitrite content is less than 0.2mg/L, the fish manure residue is fully converted into nitrate nitrogen, inorganic salts and other substances that can be absorbed and utilized by vegetables. The water then goes into the tailings pool.

The biochemically treated tail fluid is pumped into the fertilizer tank to monitor the nutrients in the water. If it meets the needs of vegetable planting, it can be directly used for vegetable cultivation in the vegetable growing area. If not, it can be sent to the water and fertilizer system for nutrient deployment, and then used Vegetable cultivation.

The above-mentioned fertilizer or nutrient solution is recycled in the vegetable planting area, and after being filtered and purified, the excess is returned to the return tank, and the aerobic treatment is performed again in the aerobic tank to remove the remaining ammonia nitrogen and nitrite. Then enter the ultraviolet disinfection machine to remove pathogenic microorganisms in the water, including bacteria, viruses, fungi and other microbial populations that are sensitive to the destructive power of ultraviolet technology. Finally, it is filtered to remove impurities such as floating objects in the water, so that the water returning to the fish pond is cleaner. The whole system is closed and circulated, and no sewage is discharged.

In the above scheme, the fish manure drum thickener comprises a frame on which a central shaft of the rotary drum is connected, the rotary drum is sleeved on the central shaft through the shaft sleeves at both ends thereof, and the rotary drum is distributed with There are several water filtering holes. The rotating drum is driven by a geared motor to rotate around its central axis. One end of the rotating drum is closed and the other end is open. The open end is the water inlet end. An air blowing device and a spray pipe are arranged in the extending direction of the central axis of the air blowing device. The air blowing device is connected to an air compressor or a high-pressure air tank. The side is provided with a number of water spray ports or water spray heads that spray water into the drum, the return pool is connected with the water spray pipe through the return water pump, the central axis of the drum is a hollow shaft, and the central axis is provided with There is a manure receiving hopper, the bottom end of the manure receiving hopper is communicated with the central axis, the top opening of the manure receiving hopper is just below the air blowing device and the spray pipe, and the top end of the manure receiving hopper extends along the length direction of the air blowing device, so the The manure sewage in the manure receiving hopper is discharged from the end of the central axis away from the water inlet end.

The fish manure sewage in the fish manure collection tank is pumped into the drum from the water inlet end by the lift pump, and the drum rotates around the central axis. discharge. The fish manure and residual bait attached to the inner surface of the drum will block the water filter hole, resulting in a decrease in the passing capacity of the water filter hole, and the water level in the drum will gradually increase. Compressed air solenoid valve, when the water surface reaches a certain height, the compressed air solenoid valve set on the pipeline connected to the air blowing device is opened, and the compressed air flow passes through the air blowing device from the outer surface of the drum to the inner surface, and adheres to the inner surface of the drum The fish manure and residual bait are blown off, fall into the manure hopper, and are discharged into the anaerobic fermentation tank through the outlet end of the central shaft. The function of spraying water from the spray pipe is to adjust the TS concentration of the concentrate, and to adjust the water output of the spray pipe to reduce or increase the TS concentration of the concentrate.

In the above solution: the frame is a water receiving box with an open upper end, and the opposite sides of the top of the water receiving box are symmetrically provided with a central axis mounting seat, and the two ends of the central axis are respectively fixed on the central axis mounting seats on both sides. , the water receiving tank is provided with a clean water outlet, and the clean water outlet is connected with the return pool. The clean water enters the water tank through the drum filter hole, and then is discharged from the water tank to the return tank.

In the above scheme: the frame is a cube or cuboid frame surrounded by transverse beams and vertical beams, and the transverse beams on opposite sides of the top end are symmetrically provided with central axis mounting seats, and the two ends of the central axis are respectively Fastened to the center shaft mounts on both sides, the rack mounts directly above the return sump.

In the above solution: the rotating drum comprises a cylindrical shell surrounded by filter sheets, one end of the cylindrical shell is closed, and the inner wall of the other end is connected with the shaft sleeve through a supporting frame, and the cylindrical shell is closed. The center of the end face is also provided with a shaft sleeve.

A driven gear is fitted on the shaft sleeve at one end of the rotating drum, and the driven gear meshes with the driving gear on the output shaft of the reduction motor. The gear is driven by the motor to rotate, thereby driving the drum to rotate around its central axis.

In the above scheme: a circular arc-shaped water inlet groove with high ends at both ends and low in the middle is arranged on the inner side of the frame, and a water inlet pipe is arranged on the side of the water inlet groove close to the frame, and the water inlet pipe extends out of the frame, and the water inlet pipe extends out of the frame. The lower end of the open end of the rotating drum is overlapped on the notch on the side of the water inlet tank away from the water inlet pipe, and a sealing member is arranged between the water inlet tank and the rotating drum. The seal is close to the drum, so that the inside and outside of the drum are strictly separated to ensure that the water entering the water inlet tank enters the drum from the water inlet end of the drum.

In the above solution: the air blowing device is an air knife.

In the above solution: the other two opposite sides of the top of the frame are provided with a cover support frame, the cover is supported above the drum through the cover support frame, and the air blowing device and the spray pipe are located in the cover case. .

In the above solution: a liquid level sensor is arranged in the drum and/or the water inlet tank. When the water surface touches the liquid level sensor, the compressed air solenoid valve set on the pipeline connected to the air blowing device opens.

Beneficial effects: The fish manure drum concentrator of the present utility model adopts pressure air backwashing, and the amount of sewage is 96%-98% less than that of general microfilter water backwashing, thereby greatly saving the water consumption of circulating water for fish farming and reducing The biochemical treatment pressure of the circulating water increases the concentration of the sewage from the fish manure concentrator, and the TS concentration of the fish manure sewage can reach an average of 5%. And the device can arbitrarily adjust the backwashing dirt TS concentration by adjusting the water volume of the water spray pipe. Sewage with higher TS concentration is suitable for anaerobic biochemical treatment. Compared with the general aerobic biochemical treatment, the energy consumption is lower, the facility capacity is smaller, and the investment is less. The utility model adopts a closed cycle of planting and breeding, zero discharge of pollutants, symbiosis of fish and vegetables, and doubled economic benefit. The utility model has high biochemical treatment efficiency, removes more than 90% of COD _cr , the final BOD ₅ <5mg/L, the nitrite content <0.2mg/L, and the treatment process <1h. The utility model can adopt the factory production mode, the management is automated, and the labor cost is greatly reduced compared with the traditional planting and breeding mode. Digital management of key links, controllable growth environment of fish and vegetables, and effective reduction of disaster risks.

Description of drawings

Figure 1 is a flow chart of the fish pond and fish manure sewage treatment and recycling system.

FIG. 2 is a schematic structural diagram of the fish manure drum thickener according to Embodiment 1 of the present invention.

FIG. 3 is a right side view of FIG. 2 .

FIG. 4 is a left side view of FIG. 2 with the deceleration motor removed.

FIG. 5 is a top view of FIG. 2 .

6 is a schematic structural diagram of the manure drum thickener of Example 2.

Detailed ways

Below by embodiment and in conjunction with accompanying drawing, the utility model is further described:

Orientation words such as front, rear, left, right, top, and bottom of the present utility model only represent relative positions in the figure, not absolute positions of products.

Embodiment 1, as shown in Figures 2-5, the fish manure drum thickener consists of a frame 1, a drum 2, a geared motor 3, a central shaft 4, an air blowing device 5, a spray pipe 6, and a central shaft mounting seat 7. , Driven gear 8, driving gear 9, water inlet trough 10, seal 11, support frame 12, cover 13, cover support frame 14 and liquid level sensor 15, water inlet pipe 16, manure hopper 17.

The rack 1 is a water receiving tank with an open upper end, which facilitates the collection of clean water. A central axis mounting seat 7 is symmetrically arranged on the opposite sides of the top of the water receiving tank, and a clean water outlet (not shown in the figure) is arranged on the water receiving tank.

A rotating drum 2 is rotatably connected to the frame 1, one end of the rotating drum 2 is closed, and the other end is open, and the open end is the water inlet end. There are several tiny water filtering holes distributed on the drum 2, preferably: the drum 2 includes a cylindrical shell surrounded by a filter screen, one end of the cylindrical shell is closed by an end plate, and the inner wall of the other end is passed through a supporting frame 12. Connected to the central shaft sleeve 201, a shaft sleeve 201 is also provided at the center of the end face of the closed end of the cylindrical shell. The central shaft 4 is a hollow shaft. Both ends of the central shaft 4 are respectively fixed on the central shaft mounting seats 7 on both sides. The other two opposite sides of the water receiving tank are provided with a cover support frame 14 , and the cover case 13 is supported above the drum 2 through the cover support frame 14 .

The rotating drum 2 is driven by the deceleration motor 3 to rotate around its central axis 4. Specifically: the shaft sleeve 201 at one end of the rotating drum 2 is covered with a driven gear 8. Preferably, the driven gear 8 is located at one end away from the water inlet of the rotating drum. The driven gear 8 meshes with the driving gear 9 on the output shaft of the reduction motor 3 .

The side wall of the water receiving tank is provided with a drum water inlet, and the inner wall of the water receiving tank is provided with a circular arc-shaped water inlet trough 10 with two ends high and the middle low, that is, the middle of the water inlet trough 10 is deep, and both ends are upturned. The notch of 10 is an arc shape that matches the cylindrical mouth of the lower part of the rotating drum 2, one side of the water inlet tank 10 is close to the inner wall of the water tank, and the side of the water inlet tank 10 that is close to the inner wall of the water tank is provided with a water inlet pipe 16, and the water inlet pipe 16 is provided. The water pipe 16 extends through the water inlet of the drum to the outside of the water receiving tank. The lower end of the open end of the drum 2 is overlapped on the notch on the side of the water inlet tank 10 away from the water inlet pipe 16 , and a seal 11 is provided between the water inlet tank 10 and the drum 2 .

An air blowing device 5 and a spray pipe 6 are arranged above the outside of the rotating drum 2 along the extending direction of the central axis 4 of the rotating drum 2 . The air blowing device 5 is connected to an air compressor or a high-pressure air tank, and the air blowing device 5 blows air into the rotating drum 2 , preferably, the air blowing device 5 is an air knife. The lower side of the spray pipe 6 is provided with a number of water spray ports or water spray heads that spray water toward the drum 2 .

A manure receiving hopper 17 is arranged on the central shaft 4. The bottom end of the manure receiving hopper 17 is communicated with the central shaft 4. When the top opening is rotated to the top, it can be located just below the air blowing device 5 and the spray pipe 6. The top end of the bucket 17 extends along the longitudinal direction of the air blowing device 5 . The manure sewage in the manure collecting bucket 17 is discharged from the end of the central shaft 4 away from the water inlet end. The reduction motor 3 , the driving gear 9 and the driven gear 8 are located at the end of the central shaft 4 away from the water inlet end. A liquid level sensor 15 is arranged in the drum 2 and/or the water inlet tank 10 .

Example 2

As shown in FIG. 6 , other parts are the same as in Embodiment 1, except that the frame 1 is a cube or cuboid frame surrounded by transverse beams and vertical beams, and the transverse beams on the opposite sides of the top end are symmetrically arranged with a central axis For the mounting seat 7, both ends of the central shaft 4 are respectively fixed on the central shaft mounting seat 7 on both sides. A cover support frame 14 is provided on the other two opposite lateral beams. The cover frame 13 is supported by the cover support frame 14. The water inlet tank 10 is directly fixed on the inner side of the transverse beam, and the water inlet pipe 16 is provided on the side of the water inlet tank 10 close to the transverse beam. , the water inlet pipe 16 extends out of the frame. The rack 1 is directly installed above the return pool, and clean water is directly discharged into the return pool.

Example 3

As shown in Figure 1, a fish pond fish farming and fish manure sewage treatment and recycling system consists of a fish pond 18, a fish manure collection tank 19, a microfilter 20, an ultraviolet sterilizer 21, a fluidized moving bed biological filter 22, a filter device 23, Backwater tank 24, anaerobic fermentation tank 25, first aerobic tank 26, sedimentation tank 27, biological filter tank 28, tail liquid tank 29, fertilizer tank 30, integrated water and fertilizer system 31, vegetable cultivation area 32, second aerobic tank 33 and the fish manure drum concentrator of embodiment 1 is formed.

The fish manure sewage at the bottom of the fish pond 18 is collected by the manure collector and then discharged into the fish manure collection tank 19. The middle and upper part of the fish pond 18 is provided with a pool surface outlet, and the manure residue in the middle and upper part of the water level of the fish pond 18 enters the microbe through the pool surface outlet. The filter 20 performs filtration, and the backwash water of the microfilter 20 enters the fish manure collection tank 19 . The clean water from the microfilter 20 enters the ultraviolet disinfection machine 21 for disinfection, the sterilized water enters the fluidized moving bed biological filter 22 , and the water from the fluidized moving bed biological filter 22 returns to the fish pond 18 .

The sewage in the fish manure collection tank 19 enters the drum 2 of the fish manure rotary drum concentrator of Example 1 and is concentrated, and the clear water outlet of the rotary drum concentrator is connected with the backwater tank 24, and the clean water that comes out enters the backwater tank 24, and the backwater tank The water in 24 is also pumped to the spray pipe 6 through the backwash pump.

After the fish manure sewage reaches TS3-5% in the fish manure drum concentrator, the concentrate enters the anaerobic fermentation tank 25, and the water from the anaerobic fermentation tank 25 enters the first aerobic tank 26, and then enters the sedimentation tank in turn. 27 and the biological filter 28, the water from the biological filter 28 enters the tail liquor pond 29, and the water in the tail liquor pond 29 enters the vegetable cultivation system.

The vegetable cultivation system includes a fertilizer pool 30, a water and fertilizer integrated system 31 and a vegetable cultivation area 32. The water pump of the tail liquid pool 29 enters the fertilizer pool 30, and the effluent of the fertilizer pool 30 enters the water and fertilizer integrated system 31 for nutrient allocation or directly to the vegetable cultivation area 32, The effluent of the integrated water and fertilizer system 31 enters the vegetable cultivation area 32 , and the excess water is recycled to the return pool 24 after being filtered and purified by the vegetable cultivation area 32 .

The water of the return pool 24 enters the second aerobic pool 33, the outlet of the second aerobic pool 33 is connected with the ultraviolet sterilizer 21, the outlet of the ultraviolet sterilizer 21 is connected with the filter device 23, and the water filtered by the filter device 23 returns to the fish pond .

Example 4

Others are the same as Example 3, the difference is that the drum 2 of the fish manure drum thickener of Example 2 is used, the frame is directly installed above the return pool 24, and the clean water directly enters the return pool 24.

The present utility model is not limited to the above-mentioned embodiments, and those of ordinary skill in the art can understand that various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and purposes of the present utility model. The scope of the novelty is defined by the claims and their equivalents.

Claims (10)

1. a fish pond culture fish manure sewage treatment and recycling system, comprising a fish pond, and the fish manure sewage at the bottom of the fish pond is discharged into a fish manure collection tank, and the middle and upper part of the fish pond is provided with a pool surface outlet, it is characterized in that: The pool surface discharge port is connected to the microfilter, the clean water from the microfilter enters the ultraviolet disinfection machine for disinfection, the disinfected water enters the fluidized moving bed biological filter, and the water from the fluidized mobile bed biological filter Back in the fish pond, the backwash water of the microfilter enters the fish manure collection tank; The sewage in the fish manure collection tank enters the fish manure drum concentrator for concentration, the clean water from the fish manure drum concentrator enters the return tank, and the concentrate from the fish manure drum concentrator enters the anaerobic fermentation tank , the water from the anaerobic fermentation tank enters the first aerobic tank, and then enters the sedimentation tank and the biological filter in turn, the water from the biological filter enters the tail liquid tank, and the water in the tail liquid tank Enter the vegetable cultivation system; The vegetable cultivation system includes a fertilizer pool, a water and fertilizer integrated system, and a vegetable cultivation area. The water pump of the tail liquor pool is pumped into the fertilizer pool, and the effluent of the fertilizer pool enters the water and fertilizer integrated system for nutrient allocation or goes directly to the vegetable cultivation area. The effluent of the integrated water and fertilizer system enters the vegetable cultivation area, and the excess water filtered and purified is recycled through the vegetable cultivation area to return to the return pool; The water in the return pool enters the second aerobic pool, the outlet of the second aerobic pool is connected with the ultraviolet sterilizer, the outlet of the ultraviolet sterilizer is connected with the filter device, and the water filtered by the filter device returns to the sterilizer. fish pond. 2. The fish pond fish dung sewage treatment and recycling system according to claim 1 is characterized in that: the fish dung rotary drum thickener comprises a frame, and the The drum is sleeved on the central axis through the shaft sleeves at both ends. The drum is distributed with a number of water filtering holes. The drum is driven by a geared motor to rotate around its central axis. One end of the drum is closed and the other end is open. , the open end is the water inlet end, an air blowing device and a spray pipe are arranged above the outside of the drum along the extension direction of the central axis of the drum, and the air blowing device is connected with an air compressor or a high-pressure air tank, The air blowing device can blow air into the drum, and the lower side of the spray pipe is provided with a number of water spray ports or water spray heads that spray water toward the drum, and the return pool passes through the return water pump and the water spray pipe. Connected, the central shaft of the drum is a hollow shaft, a manure receiving hopper is arranged on the central shaft, the bottom end of the manure receiving hopper is communicated with the central shaft, and the top opening is located at the blowing device and the spraying device. Below the pipe, the top of the manure collecting bucket extends along the length direction of the air blowing device, and the manure and sewage in the manure collecting bucket are discharged from the end of the central axis away from the water inlet end. 3. The fish pond fish dung sewage treatment and recycling system according to claim 2, characterized in that: the frame is a water receiving tank with an upper end opening, and the opposite sides of the top of the water receiving tank are symmetrically provided with a central axis to install The two ends of the central shaft are respectively fixed on the central shaft mounting seats on both sides, the water receiving tank is provided with a clean water outlet, and the clean water outlet is connected to the return tank. 4. the fish pond fish dung sewage treatment and recycling system according to claim 2, it is characterized in that: described frame is a cube or cuboid frame surrounded by transverse beam and vertical beam, the opposite sides of its top A central shaft mounting seat is symmetrically arranged on the transverse beam of the sump, the two ends of the central shaft are respectively fixed on the central shaft mounting seat on both sides, the frame is directly installed above the return pool, and the clean water from the drum is directly Drain into the return pool. 5. The fish pond fish dung sewage treatment and recycling system according to claim 3 or 4, characterized in that: the drum comprises a cylindrical shell surrounded by a filter screen, and one end of the cylindrical shell is closed , the inner wall of the other end is connected with the shaft sleeve through the support frame, and the shaft sleeve is also arranged in the center of the closed end face of the cylindrical shell. 6. The fish pond fish dung sewage treatment and recycling system according to claim 5, characterized in that: the shaft sleeve at one end of the drum is equipped with a driven gear, and the driven gear and the output shaft of the deceleration motor are on the the drive gear meshes. 7. The fish pond fish dung sewage treatment and recycling system according to claim 6, characterized in that: the inner side of the frame is provided with a circular arc-shaped water inlet with high ends at both ends and a low middle, and the water inlet is by machine One side of the frame is provided with a water inlet pipe, the water inlet pipe extends out of the frame, the lower end of the open end of the drum is overlapped on the notch on the side of the water inlet tank away from the water inlet pipe, and the gap between the water inlet tank and the drum A seal is provided. 8. The system for treating and recycling fish pond fish manure sewage according to claim 7, wherein the air blowing device is an air knife. 9. The fish pond fish dung sewage treatment and recycling system according to claim 8, characterized in that: the other two opposite sides of the top of the rack are provided with a casing support frame, and the casing passes through the casing support frame Supported above the rotating drum, the blowing device and the spray pipe are located in the casing. 10 . The fish pond and fish manure sewage treatment and recycling system according to claim 9 , wherein a liquid level sensor is provided in the drum and/or the water inlet tank. 11 .

Images