FI61019B - BIOLOGISKT FILTER FOER BEHANDLING AV BIOLOGISKT NEDBRYTBARA AVFALLSPRODUKTER INNEHAOLLANDE VAETSKA OCH ANVAENDANDE AV DETSAMMA TILL RENING AV AVFALLSVATTEN - Google Patents

Description

(g) FINNISH I — FI N LAND Patent Publication — Patent 6ft19 © Kv.lk ^ Int.CI? C 02 P 3/06 ^ © Patent application — Patentansöknlng 2930/72 0 © HakemlspSIvä —Ansökningsdag 23.10.72 @ Start date - Glltlghetsdag 23.10.72 © Published to the public - Blivit offentlig 27.05-73 @ Date of entry and publication

Ansökan utlagd och utl.skriften publlcerad 29-01.82

National Board of Patents and Registration © Patent granted-Patent meddelat 10.05.82

Patents and registries

Privilege claimed — Begärd priority 2o.ll.71 USA (US) 202 ^ 89 (73) Smith & Loveless, Inc., Lenexa, Kansas, USA (US) (72) Carl E. Burkhead, Lawrence, Kansas, USA (US) ) (7 ^) Oy Kolster Ab (5 * 0 Biological filter for the treatment of liquid containing biodegradable waste, and its use for the treatment of waste water -Biological filter for the treatment of biodegradable waste products, the product of which is used for the treatment of waste This invention relates to the present invention equipment for the treatment of biodegradable waste using aerobic microbial growth on a solid medium for the biological oxidation of waste.

The present invention relates to a biological filter for treating a liquid containing biodegradable waste, the filter comprising a closed housing with an inlet and outlet line and a column of solid medium consisting of a plurality of different elements stacked freely and randomly on top of each other in the housing. a predetermined large surface area / volume ratio and together having a predetermined high porosity so that the resistance to the fluid flowing through is small.

The filter according to the invention is characterized in that - the housing has a mixing zone consisting of a column of solid medium and bounded at the upper and lower ends of the column, 2 61019 - the inlet line is adapted to conduct sufficient liquid to keep the medium completely covered, - the outlet line is located the bottom is formed as a perforated floor forming the upper part of the flow-through and sedimentation basin, - a flow channel leads from the bottom to the top of the mixing zone, - recirculation means are adapted to pump liquid for repeated circulation from the top of the mixing zone through the bottom oxidizing and applying means for oxidizing the liquid outside the top of the mixing zone, mainly at and above it, and for spreading the oxidized liquid evenly over the entire top of the mixing zone so that the liquid is evenly distributed; mixed, which promotes aerobic microbial growth with the solid medium, and - the medium is adapted to flow uniformly through the mixing zone without attempting to detach aerobic microbial growth from the medium and form fluffy aerobic microbes.

Several methods and equipment are known in the art for the treatment of biodegradable waste materials, which provide clarified and safely returned wastewater to nature. In recent years, more and more attention has been paid to the development of waste treatment methods from an ecological point of view.

In principle, biological sewage treatment is a method in which the metabolism of microorganisms produces gaseous and molecular end products and increases bacterial cells. The speed and efficiency of the method is enhanced by increasing the number of bacterial cells, i.e., culture, that is available for metabolism. The propagation and retention of organisms in the system has previously been accomplished by physical or biological methods, such as precipitation, sedimentation, or reserving a large area for bacterial growth.

Two well-known methods for treating biodegradable waste are activated sludge and spray filter methods. In the activated sludge method, organisms are contacted with sewage by mixing the sewage with a slurry, i.e. a solid containing organism flakes, to form a mixed liquid which is then vigorously effervescent while being supplied with a large amount of air. In the jet filter method, the biological organisms are not in an aqueous medium but on the surface of suitable media as an atmosphere-susceptible culture, and the reaction is accomplished by flowing the waste in a relatively thin stream over it in direct contact with the biological slurry.

For example, U.S. Pat. No. 3,293,174 discloses a method of wastewater treatment based on the principle of a jet filter.

It comprises a member on which there is a layer of filter media which slowly passes the wastewater through, and a member for spraying the liquid onto the layer of filter media and for aerating it. Separate inactive polymeric foam bodies in random order on the filter media. In the illustrated embodiment, only a simple passage of liquid through the column is shown without any recirculation. In order to obtain a sufficiently good wastewater treatment result, it is then necessary to pass the wastewater through several such treatment units.

Combined or hybrid systems using both activated sludge and spray filter are also known in the art. In one example, upright flat asbestos cement sheets are used as contact surfaces for aerobic microbial growth. Air is blown under the plates from the openings in the bottom grille to obtain the required oxygen.

The apparatus of the present invention is more economical than prior apparatus, and produces better quality effluent water.

In the apparatus according to the invention, a single unit functions as an aeration tank, a clarification tank and an aerobic decomposer. This avoids settling ponds, sludge circulation pumps and operating problems associated with a conventional activated sludge system. In addition, the system operates at a higher microbial density and has a higher power than conventional jet filters.

The invention is described below with reference to the accompanying drawings; Fig. 1 schematically shows a vertical section of a reactor system according to the invention, and Fig. 4 61019 shows the structure of Fig. 1 seen from above.

Figure 1 shows a reaction system 10 comprising an outer jacket, i.e. a reactor device 12, formed of a metal plate or the like and having a corrosion-resistant inner surface. In this embodiment, the sheath 12 is cylindrical, however, many other shapes may be used in the apparatus of the invention. The inlet line 14 opens into the housing 12 and is located here in the vicinity of the upper end of the housing.

A liquid containing biodegradable waste products, such as sewage and / or industrial waste, is introduced into the reactor system 10 via an inlet line 14. The waste products can be raw or alternatively, they can first be treated, e.g. by screening, grinding, sand removal and / or sedimentation.

The housing 12 also comprises a effluent discharge pipe 16 treated and clarified in the reactor 10. At the end of the discharge pipe 16 there is a conventional guide dam and an effluent housing 18. The water flowing out through the pipe 20 is therefore clean so that it can be discharged into water or soil.

The housing 12 comprises a mixing zone, the upper end 22 of which is located just below the inlet channel 14 and which lower part 24 is located near the bottom of the housing 12. In this embodiment, the bottom 24 of the mixing zone is bounded by a perforated metal intermediate bottom of the housing 12. The metal base can be formed of a conventional metal grating or the like.

With the exception of the central bypass channel 26, the space between the top 22 and the bottom 24 of the entire mixing zone is filled with a solid medium 28. The solid medium 28 should be one in which the surface area to volume ratio is high, the fluid flow resistance low, i. very porous and suitable for aerobic microbial growth in terms of surface properties. For example, a plastic tower filler formed from polypropylene called “Flexirings” and manufactured by Koch Engineering Company, Inc., Wichita, Kansas, has been found to be suitable.In the laboratory test model, 2 16 mm nominal “Flexiring” with an area of 330m / In the prototype according to the invention, the volume of the mixing zone 3 of which was 1.36 m, the surface area of 92 m / m provided by 89 mm "flexing rings" was effectively utilized. Other types of fillers, such as "Rasching" and "Pall- tires "and saddle type 61019 5 (e.g.," Berl ") padding may be used without departing from the spirit of this invention. The solid medium may also be formed of non-plastic materials as long as they are non-microbially toxic and otherwise aerobic to microbial growth. suitable.

The openings in the perforated bottom 24 of the mixing zone must not be so large as to allow individual pieces of medium 28 to pass through, but they must be as large as possible in view of this limitation.

As previously mentioned, the bypass passage 26 fills the center of the mixing zone and extends from its top 22 to its bottom 24. The bypass passage 26, which may be cylindrical, forms part of a closed circulation flow path containing a solid medium 28 in the mixing zone. , although the bypass channel can be located in other places inside the housing 12 and even outside it.

According to the present invention, the solid medium 28 in the mixing zone is immersed in the liquid entering the system through the inlet channel 14. Oxidation of organic wastes in the liquid is accomplished by continuous circulation of the liquid through the medium and continuous aeration of the liquid in a manner that excites the highly active aerobic microbial growth on the solid medium 28 throughout the mixing zone. It is important for the invention that the bacterial growth adhere to the solid medium and that the fluffy or suspended aerobic bacterial growth is reduced. In other words, excessive effervescence and vortex formation within the mixing zone is avoided, which causes the bacterial system to detach from the solid medium 28. It is also important to make efficient use of the entire volume of solid medium 28, and therefore the circulation system must be designed to promote homogeneous mixing and prevent empty the creation of places, i.e. stationary pockets, within the mixing zone 28.

When using the apparatus according to the invention, the particles suspended in the wastewater adhere to the sludge on the solid medium 28. The solids remain in the medium until they are released as inactive waste pieces, thus allowing the microbes a long period of time to oxidize and stabilize the organic matter. The sludge age of this system and method, i. the time that solids remain in the medium before they are released is much longer than in a normal activated sludge system. With the system according to the invention it is possible to get close to the theoretical oxidation factor. It has also been found that the capacity of the system in the presence of sudden load peaks is very good.

It has been found that the aeration, application and circulation operations can be carried out in a very efficient and satisfactory manner by means of a mechanical surface aeration device 30 mounted at the top of the central bypass duct 26 which raises the liquid up to the bypass duct 26 and aerates the raised liquid by rotating impeller blades. into small particles of liquid, while throwing the liquid radially outward, into a substantially uniform application pattern over the top 22 of the mixing zone.

The mechanical surface aeration provided by the unit 30 causes less shear forces and agitation in the mixing zone than other methods, such as diffusion aeration. However, it will be appreciated that other aeration methods and other types of aeration units may be used in the invention instead of unit 30.

For example, an air tube may be placed in the center of the bypass passage 26, the mouth of which opens downward from some intermediate point in the length of the bypass passage 26. In this arrangement, a guide cone is placed at the upper end of the bypass duct 26 in place of the aeration device 30 so as to direct the liquid to move upwards by means of the air discharged from the central tube.

In this embodiment, the blades of the rotating impeller of the mechanical aeration device are driven by a motor unit 32 supported by a bridge 35 attached to opposite side walls of the housing 12. The motor unit 32 and the impeller unit 39 are connected to each other by a conventional drive shaft 34.

Typically, the rotor portion 30 of the aeration device is fixed to the level of the surface of the liquid so that its wings partially sink into the liquid. In order to claim possible contact with the medium 28, a coarse retaining screen can be placed in the upper part 22 of the mixing zone. In addition, it is recommended that the specific gravity of the medium 28 be at least slightly greater than the specific gravity of the water to avoid contact between the impeller blades and the medium.

61019 According to a preferred embodiment of the present invention, a sludge receiving zone is further provided inside the housing 12. The receiving zone is located below a perforated intermediate base delimiting the lower portion 24 of the mixing zone. The conical receiving basin 33 closes the lower end of the housing 12. The side walls of the conical basin 38 form an angle of approximately 60 ° with the vertical axis of the cone, thus ensuring that the slurry flows towards the tip of the cone. The slurry drain pipe 40 opens to the conical tip of the basin 38. The valve 42 mounted on the pipe 40 is occasionally opened to drain the collected sludge. Typically, the slurry is a substantially inert, solid residue that has settled from the mixing zone. The drained sludge is not recycled in the process but, on the contrary, is removed by any suitable means.

The lower end of the bypass passage 26 rests on the perforated bottom 24 of the mixing zone. The tip of the receiving basin 38 is sufficiently below the bottom 24 so that the circulating liquid does not flush the bottom of the receiving basin and does not return the sludge to the system.

For this purpose, the system is used so that the solids remain on the solid medium 28 for as long as possible. The microorganisms growing in the solid medium 28 remove solids from the stream coming from the inlet line 14 together with the dissolved impurities. The disintegrated solids occasionally detach from the solid medium 28 to settle in the receiving basin 38. Both non-biodegradable and microbiologically degraded solids have better settling properties than the inflow solids due to their greater density and size. the properties are a direct consequence of the long microbial retention time provided by the solid medium 28.

The system according to the invention was tested on a laboratory scale using a standard temperature-fermentation vessel model 40-100 as a reactor unit "VIRTIS". The reactor was operated at room temperature ranging from 21-27 ° C. The reactor volume was 10.5 L without solid medium 28, circulation tube 26, perforated bottom 24, and other submersible components. The effective liquid retention volume of the reactor with its immersed parts was 9.0 1. The inlet flow corresponding to a certain aeration time 8 61019 was based on the effective retention volume of the reactor, i. 9.0 liters.

The solid medium 28 used in the laboratory model was the polypropylene "Flexirings" bodies previously described. A total of 1,500 laboratory-sized "Flexirings" units with a nominal size of 16 mm were used. The average unit weight of the dry medium was found to be 0.5060 grams. The volume required of 1,500 units was approximately 900 ml. The described medium is inactive, normal in shape and 127 ° C without adverse effects, with an area per unit volume of 330 m / m.

The medium for this is conventional per se and has been used in the past in jet filter systems.

The studies pumped clarified sewage from a small municipal treatment plant into a model reactor with a pump manufactured by Fluid Metering, Inc., model RRP. In order for the pumping speed to keep the consistency was placed between the supply container and the pump inlet side of the tube a conventional constant-pressure apparatus. The sewage water was pumped into the biological reactor without interruption at a constant rate to obtain the desired aeration time. Complete aeration and agitation was achieved with a magnetically driven flat-bladed turbine housed in a central circulation tube 26.

Initially, the reactor was operated with an aeration time of 12 hours for a period of 127 days. In addition, the studies were continued for 26 days using a 6-hour aeration time. With a retention time of 12 hours, the total chemical oxygen demand (COD) of the inflowing effluent was averaged 202 mg / l, and the total COD of the inflowing solute was found to be 111 mg / l. The mean total COD of the effluent solute was found to be 31 mg / l. The total COD and soluble COD of the effluent were essentially the same because the amount of suspended solids in the effluent was negligible.

During the 6-hour retention period, the mean total COD of the influx was 508 mg / L, and the mean soluble COD of the inflow was 240 mg / L. The mean total COD of the effluent was 30 mg / l.

More limited studies were performed on biological oxygen demand (BOD). During the analyzes, the mean total BOD of the 9,61019 inflows was 98 mg / l and the mean BOD of the solution was 53 mg / l. During the 6 hour retention period, the mean BOD of the inflowing substance was 174 mg / l, while the mean BOD of the solution was about 88 mg / l.

During the twelve hour retention period, the amount of inflowing suspended solids ranged from 10 to 137 mg / L, with a mean of 65 mg / L. The amount of suspended solids flowing out ranged from 0 to 5 mg / l and the average was 3 mg / l. About 80% of the total suspended solids were volatile. With a retention time of 6 hours, the average inflow of suspended solids was 121 mg / l and the average outflow of suspended solids was 14 mg / l.

It was also found that with a retention time of 12 hours, almost complete nitrification occurred when mixing was appropriate and when sufficient dissolved oxygen was present. The pH of the effluent and inflow was measured at regular intervals and ranged from 7.1 to 7.8. The dissolved oxygen of the mixed liquid in the circulation tube was measured from time to time. The amount of dissolved oxygen was 1.5-2.4 mg / l.

Microscopic examination of the biological solid on a solid medium showed that the microbes were always similar to the microbes found in the activated sludge system. Using a 12-hour retention time, the solid-containing biological solids contained higher organisms than during the 6-hour studies.

Throughout the study, the system produced very good quality effluent when the result is estimated from the purification percentage based on the COD and BOD content of the effluent and the suspended solids. During the 12-hour retention period, the system was able to remove 85% of the total amount of KHT, 95% of BHT, and 95% of the total suspended solids. During the six-hour retention period, the system removed 85% of the KHT, 86% of the BOD and 88% of the suspended solids.

Claims (5)

61019 10 A biological filter for treating a liquid containing biodegradable waste, the filter comprising a closed housing with an inlet discharge line and a column of solid medium consisting of a plurality of different elements stacked freely and randomly on top of each other in the housing, each having a predetermined large area / volume ratio and having a predetermined high porosity with low resistance to the fluid flowing through, characterized in that - the housing (12) has a mixing zone consisting of a column (28) of solid medium and bounded by the top of the column. and the lower end, - the inlet line (14) is adapted to conduct sufficient liquid to keep the medium (28) completely covered, - the outlet line (16) is arranged in connection with the mixing zone between this upper part (22) and the base (24), the base being a perforated floor (24), which forms the upper part of the flow-through and sedimentation basin (38), - it the recirculation means are adapted to pump liquid for repeated circulation from the top (22) of the mixing zone along the path leading to its bottom (24) and back through the channel (26), the recirculation means comprising an oxidizing and spreading member (30); ) to oxidize the liquid outside, mainly at and above the top of the mixing zone (22) and to spread the oxidized liquid evenly over the entire top of the mixing zone so that the liquid is uniformly mixed, promoting aerobic microbial growth with the solid medium (28), and - the medium is adapted to the flow occurs evenly through the mixing zone without attempting to detach aerobic microbial growth from the medium and form fluffy aerobic microbes. Biological filter according to claim 1, characterized in that the floor (24) delimits the mixing zone in the bottom housing (12) and that the sedimentation basin (38) is tapered from below so that a zone substantially receiving the bottom precipitate is formed outside the liquid flow path and a sludge outlet pipe (40) for the occasional removal of the bottom sludge accumulated in the basin. Biological filter according to Claim 1 or 2, characterized in that the oxidation and application element is a mechanical surface mixer (30) arranged at the top of the mixing zone and in connection with the flow channel (26). 61019 Biological filter according to one of Claims 1 to 3, characterized in that a flood threshold (18) is connected to the clarified liquid discharge line (16) of the tank, which communicates with the mixing zone between the top and bottom of this zone, substantially at the top of the mixing zone (22). Use of a filter according to any one of claims 1 to 4 for the treatment of waste water. 12 61019