CN218073068U

CN218073068U - Energy-efficient recirculating aquaculture system

Info

Publication number: CN218073068U
Application number: CN202221990816.XU
Authority: CN
Inventors: 陈文祥; 黄文华; 汤爱萍; 念小弟; 徐晓津
Original assignee: Fujian Yufeng Fishery Trade Co ltd
Current assignee: Fujian Yufeng Fishery Trade Co ltd
Priority date: 2022-07-30
Filing date: 2022-07-30
Publication date: 2022-12-20
Anticipated expiration: 2032-07-30

Abstract

The efficient energy-saving recirculating aquaculture system sequentially comprises an aquaculture pond, a microfiltration device, a trickling filter, a biological filler pond, a sterilization device and an oxygenation device along the water flow direction, wherein the water outlet end of the oxygenation device is connected to the aquaculture pond through a backwater water inlet pipe, a water stabilizing loop is further arranged between the water outlet end of the biological filler pond and the water inlet end of the trickling filter, and 20-30% of water in the biological filler pond flows back into the trickling filter through the water stabilizing loop. The utility model discloses 20-30% play water reflux and the breed reuse water in with the biological filler pond are mixed, improve the content of nitrobacteria and denitrifying bacteria in the circulating water to at the drip device internal culture, obtain the growth in the biological filler pond again and breed, nitrify and the denitrification reaction, with organic matter and the ammonia nitrogen of getting rid of the circulating water, improved the biochemical treatment efficiency of circulating water.

Description

Energy-efficient recirculating aquaculture system

Technical Field

The utility model relates to an aquaculture technical field, more specifically say and indicate an energy-efficient recirculating water aquaculture system.

Background

The recirculating aquaculture system is a novel aquaculture mode, and wastewater generated in an aquaculture pond is treated by a series of water treatment units and then recycled. The principle of the system is that harmful pollutants such as residual bait, excrement, ammonia nitrogen and nitrite in the aquaculture water are removed by combining physical filtration, biological filtration, disinfection and the like, the purpose of purifying the environment of the aquaculture water is achieved, and the purified water is input into the culture pond again.

At present, after ammonia nitrogen and nitrite in circulating water of the existing circulating water aquaculture system are removed through a biological filler pond, all the circulating water is directly discharged into an ultraviolet disinfection device for disinfection. The disinfection mode can easily kill most of nitrifying bacteria and denitrifying bacteria together, so that the content of the nitrifying bacteria and the denitrifying bacteria in the recycled water is greatly reduced, the nitrifying bacteria and the denitrifying bacteria in the biological filler pond grow slowly, the biochemical treatment time of the circulating water is greatly prolonged, and the treatment efficiency of a circulating water culture system is reduced.

In addition, a plurality of cultivation barrels are arranged in the cultivation pond of the recirculating aquaculture system, and each cultivation barrel is adhered with dirt and bacteria after cultivation for a period of time. Therefore, it is necessary to clean it regularly. Chinese utility model patent that bulletin number is CN 213756262U discloses a novel fry incubator, including breeding the case, breed bottom of the case central point position and be equipped with the motor, the pivot is connected to the output shaft one end of motor, the fixing base is connected on the pivot top, a plurality of connecting rods and installing support fixed connection that evenly distributed are passed through to the fixing base outer periphery, the installing support surface interval is equipped with a plurality of mounting holes, the mounting hole of installing support is equipped with branch and branch bottom portion threaded connection fastening nut, the outside both sides of branch are equipped with two brushes and two brush on the branch are close to in breeding the incasement wall.

The fry incubator mainly comprises a motor, a mounting bracket, a first brush and a second brush, wherein the mounting bracket is arranged on a fixing seat, the first brush is arranged on the mounting bracket, the second brush is arranged on a supporting rod, and the inner surface of the bottom of the incubator is cleaned by the first brush. Although the cultivation box can be cleaned, the power is provided by the motor, so that the input cost and the operation cost of equipment are increased; and the culture box needs to be elevated when being installed, and the bottom is provided with a rotating shaft, so that the installation is complicated.

Therefore, an efficient and energy-saving recirculating aquaculture system is provided.

SUMMERY OF THE UTILITY MODEL

The utility model provides an energy-efficient recirculating water aquaculture system to solve present recirculating water aquaculture system and will discharge through biological filler pond's whole circulating water and disinfect in discharging degassing unit, lead to most good oxygen fungus and anaerobe to be eliminated, reduced the treatment effeciency and the treatment quality scheduling problem of circulating water.

The utility model adopts the following technical scheme:

the utility model provides an energy-efficient recirculating water aquaculture system, includes breed pond, micro-filtration device, trickling filter, biological filler pond, sterilizing equipment and oxygenation device in proper order along the water flow direction, the play water end of oxygenation device is connected to through the return water inlet tube breed the pond, still be equipped with a steady water return circuit between the play water end of biological filler pond and the end of intaking of trickling filter, this steady water return circuit makes 20-30% play water reflux in the biological filler pond to in the trickling filter.

In a preferred embodiment, a plurality of cultivation barrels are arranged in parallel along the length direction of the cultivation pond in the cultivation pond, a water outlet of each cultivation barrel is connected to a water discharge channel, and a water outlet end of the water discharge channel is connected with a water inlet end of the micro-filtration device.

In a preferred embodiment, the water outlet is arranged at the center of the bottom of the cultivation barrel, a self-cleaning device is installed in each cultivation barrel, the self-cleaning device comprises a central cylinder, a sleeve and a rotating support rod, the bottom of the central cylinder is of a hollow structure and is vertically fixed at the water outlet, a plurality of through holes are formed in the outer side wall of the central cylinder at intervals, the sleeve is sleeved outside the central cylinder, a plurality of open grooves communicated with the through holes of the central cylinder are formed in the outer side wall of the sleeve, at least one first brush strip is arranged on the inner side wall of the sleeve and parallel to the central shaft of the central cylinder, the inner side of the first brush strip is in contact with the outer surface of the central cylinder, the rotating support rod is fixedly connected to the side face of the bottom of the sleeve, and a second brush strip in contact with the bottom face of the cultivation barrel is fixedly arranged on the bottom face of the rotating support rod.

In a preferred embodiment, an anti-escape net is fixedly sleeved on the outer side wall of the central cylinder, and the inner side of the first brush strip is in contact with the outer surface of the anti-escape net.

In a preferred embodiment, the microfiltration device comprises a microfiltration tank and a microfiltration machine, the microfiltration tank is internally provided with the microfiltration machine, the water inlet end of the microfiltration machine is connected with the water outlet end of the drainage channel, the sewage outlet of the microfiltration machine is connected with a sewage treatment device, and the water outlet of the microfiltration machine is connected to the trickling filtration device through a water pump.

In a preferred embodiment, the micro-filtration device, the trickling filtration device, the biological filler tank and the sterilization device are sequentially arranged along the side surface of the length direction of the drainage channel, a drainage groove is further arranged on the side surface of the water outlet end of the sterilization device, the water outlet end of the drainage groove is connected with the oxygenation device, and the oxygenation device is arranged on the side surface of the micro-filtration device.

In a preferred embodiment, above-mentioned trickling filter includes a plurality of basin, trickling filter mechanism and axial compressor negative pressure air fan, a plurality of the basin is located side by side drip filter mechanism's top, and the circulating water after the microfilter filters promotes to each through the water pump in the basin, and every a plurality of trickling filter holes have been seted up to the bottom of basin, drip filter mechanism includes a frame and a plurality of layers of rattan cotton, the frame is equipped with a plurality of layers of support frame along the interval in the vertical direction, is equipped with the one deck on every layer of support frame rattan cotton, every adjacent two-layer have the interval more than 30cm at least between the rattan cotton, the rattan cotton of top layer with also have the interval more than 30cm between the basin bottom surface, axial compressor negative pressure air fan locates the terminal side of basin rivers direction, and with the frame is relative.

In a preferred embodiment, the sterilization device comprises a sterilization tank and a plurality of ultraviolet sterilization lamps installed in the sterilization tank.

It can be seen from the above description that the structure of the present invention is more advantageous than the prior art:

1. according to the circulating water culture system with the structure, a water stabilizing loop is further arranged between the water outlet end of the biological filler pond and the water inlet end of the trickling filter, so that 20-30% of the water outlet in the biological filler pond flows back to the trickling filter, so that part of the water outlet is mixed with culture recycled water, the content of nitrobacteria and denitrifying bacteria in the circulating water is increased, the mixed water is cultured in the trickling filter and then enters the biological filler pond to grow and reproduce, nitrification and denitrification reactions are carried out, organic matters and ammonia nitrogen in the circulating water are removed, and the biochemical treatment efficiency of the circulating water is improved.

2. The recirculating water aquaculture system of this structure, be equipped with self-cleaning device in every breed bucket, the characteristics of vortex form during rivers circulation in utilizing the aquaculture pond, with the fixed delivery port of establishing at circular breed bottom of the pool center of central drum, a sleeve is established to the outside cover of central drum, and connect a rotation branch bottom the sleeve, telescopic inside wall and the bottom of rotating branch all are equipped with the brush strip, under the drive that aquaculture pond rivers flow, rotation branch and sleeve rotate around central drum, the brush strip is scrubbed the bottom in circular breed pond and the lateral wall of central drum respectively, with detach its surperficial dirt and bacterium, and discharge from the delivery port along with rivers. This automatically cleaning device need not wash the pond with the help of outside power device automatically, and it is convenient not only to install, and equipment input and use cost are low moreover.

3. The trickling device of the recirculating aquaculture system filters the circulating water through the microfilterRemoving coarse particle impurities, introducing into a water tank, forming a trickling water curtain through trickling filter holes, fully contacting with air, and making most of CO in water body under the action of axial flow negative pressure fan ₂ Is taken away by negative pressure airflow; because the lower part of the water tank is also provided with the multi-layer rattan cotton, the trickling water curtain sequentially passes through the multi-layer rattan cotton, and the characteristics of dense hole gaps and good water permeability and air permeability of the rattan cotton are utilized, so that the trickling water curtain can be formed by circulating water in the gaps of the rattan cotton, the surface area and time for the contact of the water body and air are increased, and the residual CO in the water body ₂ Most of the gas is taken away by negative pressure airflow to improve CO ₂ The amount of removal of (a); and moreover, the multi-layer rattan cotton can also filter out mycoderm and bacteria and insects in the circulating water, so that nitrobacteria can be cultured in the circulating water, the concentration of ammonia nitrogen and nitrite is reduced, and the cyclic utilization rate of the culture water is improved.

Drawings

Fig. 1 is a process flow diagram of the present invention.

Fig. 2 is a top view of the first embodiment of the present invention.

Fig. 3 is a front view of a cultivating barrel according to an embodiment of the present invention.

Fig. 4 is a top view of a cultivating barrel according to an embodiment of the present invention.

Fig. 5 is an enlarged view of a in fig. 4.

Fig. 6 is an exploded view of a trickling filter according to an embodiment of the present invention.

Fig. 7 is a left side view of a trickling filter according to an embodiment of the present invention.

Fig. 8 is a top view of the second embodiment of the present invention.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings. Numerous details are set forth in the following description in order to provide a thorough understanding of the present invention, but it will be apparent to one skilled in the art that the present invention may be practiced without these details. Well-known components, methods and processes are not described in detail below.

Example one

The utility model provides an energy-efficient recirculating water aquaculture system, refers to fig. 1, includes culture pond 1, micro-filtration device 2, trickling filter 3, biological filler pond 4, sterilizing equipment 5 and oxygenation device 6 in proper order along the water flow direction, and oxygenation device 6's the delivery end is connected to culture pond 1 through return water inlet tube 61.

Referring to fig. 2, a plurality of cultivation barrels 11 are arranged in parallel along the length direction of the cultivation pond 1, and the cultivation barrels 11 may be arranged in one row or in multiple rows. In fig. 2 of this embodiment, two rows of cultivation barrels 11 are provided in the cultivation pond. The cultivation barrels 11 are preferably circular, and each cultivation barrel 11 is internally provided with a return water inlet pipe 61, and the water outlet end of the return water inlet pipe 61 points to the non-central position of the cultivation barrel. The center of the bottom of each cultivation barrel 11 is provided with a water outlet 110, and when water flow circulates, vortex flow is formed in the circular cultivation pond.

An automatic cleaning device is also arranged in each breeding barrel 11. Referring to fig. 3 to 5, the self-cleaning device includes a central cylinder 12, a sleeve 13 and a rotating rod 14, wherein the bottom of the central cylinder 12 is hollow and is vertically fixed at the water outlet 110. The outer sidewall of the central cylinder 12 is provided with a plurality of through holes 121 at intervals, in this embodiment, a plurality of sets of through holes are specifically provided along the outer circumferential surface of the central cylinder 12, and each set of through holes includes a plurality of through holes 121 at intervals along the vertical direction. The through hole 121 is formed in the outer side wall of the central cylinder 12, so that water can be conveniently passed through the through hole 121, and water flows out of the water outlet 110 in the bottom of the cultivation barrel.

Referring to fig. 3, the sleeve 13 is sleeved outside the central cylinder 12, and a plurality of open slots 130 communicated with the through hole of the central cylinder are formed on the outer side wall of the sleeve 13. Specifically, the sleeve 13 shown in this embodiment includes an upper ring 131, a lower ring 132 and a plurality of vertical connecting plates 133, the upper ring 131 and the lower ring 132 are vertically sleeved on the upper portion and the bottom portion of the central cylinder 12, the top ends of the vertical connecting plates 133 are spaced along the outer circumference of the upper ring 131, the bottom ends of the vertical connecting plates 133 are fixed on the outer circumference of the lower ring 132, and the gap between every two vertical connecting plates 133 forms the above-mentioned opening slot 130.

Referring to fig. 3, in order to prevent the fry from escaping from the through hole of the central cylinder 12, an escape-preventing net 122 is fixedly sleeved on the outer side wall of the central cylinder 12.

Referring to fig. 3 and 5, one or any several vertical connecting plates 133 on the sleeve 13 are provided with a brush strip one 134 inside, and in the embodiment, the two symmetrical vertical connecting plates 133 are respectively provided with a brush strip one 134 inside. The brush bars one 134 are parallel to the central axis of the central cylinder 12, and the inner side of each brush bar one 134 is in contact with the outer surface of the escape-proof net 122 to wash dirt and bacteria on the outer surface of the escape-proof net 122 when the sleeve 13 rotates.

Referring to fig. 3 and 4, a rotary supporting rod 14 is fixedly connected to the bottom side of the sleeve 13, and the bottom surface of the rotary supporting rod 14 is parallel to the bottom surface of the cultivation barrel 11. The rotating support rod 14 of the embodiment is fixedly welded on the outer side wall of the bottom of one of the vertical connecting plates 133, and the bottom surface of the rotating support rod 14 is fixedly provided with a second brush strip 141 which is in contact with the bottom surface of the circular culture pond 11.

Referring to fig. 3, the rotating rod 14 extends from one end of the outer surface of the sleeve 13 to the inner side wall of the cultivating barrel 11, but does not contact the inner side wall of the cultivating barrel 11, and the length of the brush strip two 141 is the same as that of the rotating rod 14.

Driven by the flow of water in the breeding barrel 11, the rotating support rod and the sleeve thereof automatically rotate around the central cylinder, and the first brush strip and the second brush strip respectively brush the bottom of the breeding barrel 11 and the outer side wall of the central cylinder to remove dirt and bacteria on the surface of the breeding barrel and are discharged from the water outlet along with the water flow.

Referring to fig. 2, the water outlet of each row of cultivation barrels 11 is connected to a water discharge channel 101, and the water outlet end of the water discharge channel 101 is connected to the water inlet end of the micro-filtration device 2. The microfiltration device 2 comprises a microfiltration tank 21 and a microfiltration machine 22, wherein the microfiltration tank 21 is internally provided with the microfiltration machine 22, the water inlet end of the microfiltration machine 22 is connected with the water outlet end of the drainage channel, the sewage outlet of the microfiltration machine 22 is connected with a sewage treatment device, and the water outlet of the microfiltration machine 22 is connected to the trickling filtration device 3 through a water pump.

Referring to fig. 6 and 7, the trickling filter apparatus 3 includes a plurality of water tanks 31, a trickling filter mechanism 32, and an axial-flow negative pressure fan 33. The water tank 31 is a cuboid structure with an opening on the top surface, so that the inner wall and the bottom of the water tank are convenient to clean. The water tanks 31 are arranged above the trickling filter mechanism in parallel at equal intervals.

Referring to fig. 6 and 7, the circulating water filtered by the micro-filter is lifted to each water tank 31 by a water pump, and a plurality of trickling filter holes 310 are opened at the bottom of each water tank 31. The water flow in the water tank 31 flows from the front end of the water tank 31 to the rear end thereof along the longitudinal direction thereof. The aquaculture circulating water enters the water tank after being filtered by the micro-filter to remove coarse particle impurities, and forms a trickling water curtain through the trickling filter holes 310.

Referring to fig. 6, the trickling filter mechanism 32 includes a frame 321 and a plurality of layers of rattan cotton 322. The frame 321 is also a rectangular parallelepiped structure, and has the same length as the water tank 31. A plurality of support bars 3211 are spaced apart from each other along a length extending direction of the top end of the frame 321, and the water tank 10 is fixedly supported by the plurality of support bars 3211.

Referring to fig. 6, the frame 321 is provided with a plurality of supporting frames 3212 at intervals along the vertical direction. The support frame 3212 has at least three layers, the support frame 212 shown in this embodiment has five layers, and each layer of the support frame 3212 is provided with a layer of rattan cotton 322. At least a distance of more than 30cm is reserved between every two adjacent layers of the rattan cotton 322, and a distance of more than 30cm is reserved between the rattan cotton at the topmost layer and the bottom surface of the water tank 31.

Referring to fig. 6, each layer of kava cotton 322 includes several kava cotton with the same specification and arranged along the water flow direction of the water tank 31. Each rattan cotton has a gauge of 1m x 2m x 30mm and a density of 40 kg/cubic meter. Each layer of the rattan cotton 322 is divided into a plurality of small-sized rattan cotton, so that the rattan cotton can be conveniently replaced and cleaned.

Referring to fig. 6, the axial-flow negative pressure fan 33 is provided on a side surface of the water tank 31 at the end in the water flow direction, and faces the chassis 321. The axial-flow negative pressure fan 33 is mainly used for discharging CO after the drip water curtain is fully contacted with air ₂ Quickly pumping out CO in the circulating water ₂ The discharge efficiency of (2).

Referring to fig. 2, the effluent of the trickling filter 3 flows into a biological filler tank 4, and a plurality of biological balls coated with MBBR biological filler are placed in the biological filler tank 4. The circulating water effectively removes organic matters and ammonia nitrogen in the water body under the nitrification and denitrification actions in the biological filler tank.

The utility model discloses a biological filler pond 4 can also adopt the inventor at the biochemical pond of the utility model discloses that the bulletin number is CN 216837311U authorized, and this paper does not do specific details.

Referring to FIG. 1, 70-80% of the effluent from the biological filler tank 4 flows to the disinfection device 5. The disinfection device 5 comprises a disinfection tank and a plurality of UV disinfection lamps 52 installed in the disinfection tank 51. The rest 20-30% of the effluent in the biological filler tank flows back to the trickling filter device 3 through a water stabilizing loop, so that the part of the effluent is mixed with the recycled culture water, and the content of nitrobacteria and denitrifying bacteria in the recycled water is improved.

Referring to fig. 2, the microfiltration device 2, the trickling filter 3, the biological filler tank 4 and the sterilization device 5 are sequentially arranged along the side surface of the length direction of the drainage channel 101, the side surface of the water outlet end of the sterilization device 5 is also provided with a drainage channel 501, the water outlet end of the drainage channel 501 is connected with the oxygenation device 6, and the oxygenation device 6 is arranged on the side surface of the microfiltration device 2. Specifically, the oxygen increasing device 2 may adopt the oxygen increasing device disclosed in the utility model with the license number CN 216853474U, which is not described herein in detail.

Referring to fig. 2, the water outlet end of the aerator 2 is connected to a water return channel 201, a water return channel 102 is disposed beside the water discharge channel 101, the water return channel 201 is communicated with the water return channel 102, and a plurality of water return inlet pipes 61 are disposed on the water return channel 102.

In addition, referring to fig. 1, a heating device 7 can be arranged between the sterilizing device 5 and the oxygenation device 6, and the heating device 7 preferably adopts an air energy heat pump so as to heat the aquaculture water body in winter with low air temperature and provide the water body with proper temperature for the aquaculture barrel.

Example two

Referring to fig. 8, the embodiment shows two sets of symmetrically arranged circulating water culture systems, return water tanks 201 of the two sets of circulating water culture systems are isolated by water inlet valves 202, when one set of circulating water system fails, the water inlet valves 202 can be opened, and water is temporarily supplied by the other set of circulating water culture system to prevent aquatic products from dying.

The above-mentioned be the utility model discloses a concrete implementation way, nevertheless the utility model discloses a design concept is not limited to this, and the ordinary use of this design is right the utility model discloses carry out immaterial change, all should belong to the act of infringement the protection scope of the utility model.

Claims

1. The utility model provides an energy-efficient recirculating water aquaculture system, includes culture pond, micro-filtration device, trickling filter, biological filler pond, sterilizing equipment and oxygenation device in proper order along water flow direction, the play water end of oxygenation device advances water piping connection through the return water and is connected to culture pond, its characterized in that: and a water stabilizing loop is also arranged between the water outlet end of the biological filler tank and the water inlet end of the trickling filter, and the water stabilizing loop enables 20-30% of water in the biological filler tank to flow back to the trickling filter.

2. The high-efficiency energy-saving recirculating aquaculture system of claim 1, wherein: the culture pond is internally provided with a plurality of culture barrels which are arranged in parallel along the length direction of the culture pond, the water outlet of each culture barrel is connected to a water drainage channel, and the water outlet end of the water drainage channel is connected with the water inlet end of the micro-filtration device.

3. An efficient and energy-saving recirculating aquaculture system as claimed in claim 2, wherein: the delivery port is located breed the bottom center of bucket, an automatically cleaning device of installation in every breeding bucket, automatically cleaning device includes central drum, sleeve and rotation branch, central drum bottom is hollow out construction to the vertical fixation is in delivery port department, spaced apart on the lateral wall of this center drum is equipped with a plurality of through-holes, the muffjoint is established the outside of center drum, seted up on this telescopic lateral wall a plurality of with the communicating open slot of through-hole of center drum, be equipped with a brush strip one at least on the telescopic inside wall, brush strip one is on a parallel with the center pin of center drum, and brush strip one the inboard with the outer surface contact of center drum, telescopic bottom side fixed connection one rotation branch, the bottom surface of rotation branch fixed be equipped with one with breed the brush strip two of bucket bottom surface contact.

4. An efficient and energy-saving recirculating aquaculture system as claimed in claim 3, wherein: an anti-escape net is fixedly sleeved on the outer side wall of the central cylinder, and the inner side of the first brush strip is in contact with the outer surface of the anti-escape net.

5. An efficient and energy-saving recirculating aquaculture system as claimed in claim 2, wherein: the microfiltration device comprises a microfiltration tank and a microfiltration machine, wherein the microfiltration tank is internally provided with the microfiltration machine, the water inlet end of the microfiltration machine is connected with the water outlet end of the drainage channel, the sewage outlet of the microfiltration machine is connected with a sewage treatment device, and the water outlet of the microfiltration machine is connected to the trickling filtration device through a water pump.

6. The high-efficiency energy-saving recirculating aquaculture system of claim 2, wherein: micro-filtration device, trickling filter, biological filler pond, sterilizing equipment along the side of drainage canal length direction sets gradually, sterilizing equipment's play water end side still is equipped with a water drainage tank, water drainage tank's play water end is connected the oxygenation device, this oxygenation device is located the side of micro-filtration device.

7. The high-efficiency energy-saving recirculating aquaculture system of claim 1, wherein: the trickling filter device includes a plurality of basin, trickling filter mechanism and axial compressor negative pressure air fan, a plurality of the basin is located side by side the top of trickling filter mechanism, and circulating water after the microstrainer filters promotes to each through the water pump in the basin, and every a plurality of trickling filter holes have been seted up to the bottom of basin, trickling filter mechanism includes a frame and a plurality of layers of rattan cotton, the frame is equipped with a plurality of layers of support frame along the interval on the vertical direction, is equipped with the one deck on every layer of support frame the rattan cotton, every adjacent two-layer have the interval more than 30cm at least between the rattan cotton, the rattan cotton of top layer with also have interval more than 30cm between the bottom surface of the basin, axial compressor negative pressure air fan locates the terminal side of basin rivers direction, and with the frame is relative.

8. The high-efficiency energy-saving recirculating aquaculture system of claim 1, wherein: the sterilizing device comprises a sterilizing tank and a plurality of ultraviolet sterilizing lamps arranged in the sterilizing tank.