KR20010000876A - Internally-recycled aerobic biofilm reactor and the operation method of the reactor - Google Patents

Abstract

PURPOSE: An inner circulation type aerobic biofilm reactor is provided to solve the difficulty of the application of media to the aerobic tanks of conventional wastewater treatment process. The application of the inner circulation type aerobic biofilm reactor is also expected to solve the short HRT, shutting down under extremely high loading rate, and clogging problems of packed-bed reactors. CONSTITUTION: An inner circulation type aerobic biofilm reactor includes a biological packed-bed reactor (2) located in an aerobic tank (10), media (3) packed into the biological packed-bed reactor, a net (4) used to prevent media from draining away, a diffuser (5,6) used to supply air. The biological packed-bed reactor is located below the surface of the aerobic tank. The diffuser (6) beneath the biological packed-bed reactor is operated to supply much air than other diffusers (5). As a result of this operation, two currents of water, upflow (2) and downflow (9), is made in the aerobic tank. These currents help to recycle treated water from the biological packed-bed reactor. Expected results is achieved by this mechanism.

Description

INTERNALLY-RECYCLED AEROBIC BIOFILM REACTOR AND THE OPERATION METHOD OF THE REACTOR}

The present invention relates to a reaction tank used for the treatment of wastewater using a general biological treatment process, and more particularly, to install a built-in carrier-filled fixed bed biofilm reactor that occupies some space in an aerobic tank, and a large portion of the total required aeration air volume (60). %) Is injected from the diffuser at the bottom of the fixed bed biofilm reactor to induce excessive upflow into the fixed bed biofilm reactor by air lift and to operate the waste water continuously to internally circulate from the fixed bed biofilm reactor into the aeration tank. A new type biofilm reactor operated with mixed reactor characteristics and a method of operating the same.

At present, a biological treatment method using activated sludge is widely used as a treatment method of wastewater. Such biological treatment process using activated sludge is generally composed of a biological reaction tank for reacting the activated sludge of waste water and a precipitation tank for sedimentation of the activated sludge in the form of slurry discharged from the biological reaction tank to the supernatant and sludge. The settling tank is composed of a structure that discharges the supernatant water formed in the upper part, discards some of the sludge formed in the lower part, and re-inserts the waste water into the bioreactor. On the other hand, the characteristics of the activated sludge shows a large difference depending on the type of wastewater to be treated, the process operating temperature or the humidity according to the season. That is, even under the same organic material loading conditions, the microbial composition of activated sludge occurs depending on the operating conditions of the bioreactor, and the settling characteristics of the sludge (Sludge Volume) and SVI (Sludge Volume) according to the microorganism composition of the activated sludge Index) shows a big difference and affects the solid-liquid separation efficiency of the sedimentation tank. Therefore, a method that can identify the solid-liquid separation efficiency of the sedimentation tank and utilize it as an operation control factor is required. In addition, the solid-liquid separation ability of the sedimentation tank is different depending on the microorganism composition of the activated sludge under the same surface load conditions of the sedimentation tank. This conventional activated sludge biological treatment method cannot continuously monitor the characteristics of activated sludge and thus cannot predict the problem of microbial composition of activated sludge. There is a problem that the process is inefficient because the operation is made in the post-control method.

In recent years, many types of biofilm reactors have been introduced. In the case of biofilm method in which the microbial contact agent that attaches and multiplies the microorganisms is installed in the wastewater treatment facility, the microorganism is attached to the carrier at high concentration to prevent the sludge from swelling. In addition, the removal efficiency is good even at high / low concentration loads, and sludge generation is low, sludge conveying is unnecessary, economical in terms of facility cost and power cost, small reactor size, and flexible response to processing volume. There is an advantage. Among the biofilm reactors having such various advantages, packed-bed type reactors using small microbial carriers having high efficiency have been commercialized. In particular, Degremont, France, has developed a Biofor process filled with a carrier called Bioolite, which is developed in-house, and is recognized for its world-class technology. OTV is recognized for its polystyrene balls. Biofilter reactors equipped with various types of fillers, such as balls, polystyrene support layers, and polystyrene filtration layers, have been developed and marketed. These reactors are highly treated reactors that take into account the removal of nitrogen and phosphorus as well as organic and SS (suspended solid), and generally have excellent performances such as 70 to 95% nitrification rate, 40 to 90% TN removal rate and 40 to 90% TP removal rate. Do. However, this plug flow type reactor has a high removal efficiency, but is weak to impact load on influent sewage, and has a low hydraulic retention time per unit volume due to the filled carrier, and intermittent due to sludge deposition during long-term operation. It is difficult to use in small sewage treatment facilities because it is difficult to operate, such as having to clean the plant.

The present invention has been made to solve the above-mentioned problems, and built a carrier-filled fixed bed biofilm reactor by delimiting a portion of the existing activated sludge type aerobic tank, and waste water is continuously transported from the fixed bed biofilm reactor into the aerobic tank continuously. By operating it as a whole, the entire treatment system is operated with the characteristics of a fully mixed reactor, which enables the treatment of high load wastewater, facilitates the flow of downflow in the aeration tank, shows high removal efficiency, prevents sludge accumulation in the carrier, and does not require back washing. The purpose is to present a new type of biofilm reactor and its operation method.

1 is a perspective view schematically showing a small sewage treatment system and a sewage flow chart in which a fixed bed biofilm reactor is built in a complete mixing reactor according to the present invention;

2a is a plan view schematically showing a complete mixing reactor in which a plurality of fixed bed biofilm reactors are installed in a large sewage treatment system according to the present invention;

Figure 2b is a side view schematically showing a complete mixing reactor in which a plurality of fixed bed biofilm reactors are installed in a large sewage treatment system according to the present invention.

Explanation of symbols on the main parts of the drawings

1 ... aerobic 5, 6 ... diffuser

2 ... fixed bed biofilm reactors 7 ... influent

3 ... carrier 8 ... effluent

4 ... network 9 ... internal circulation

10 ... complete mixing reactor

As a technical configuration for achieving this object, the present invention,

In a reaction tank used for treating wastewater using a biological treatment process, a fixed bed biofilm reactor, which occupies some space in an aerobic tank, is installed and an excessive amount of air is injected from an acid pipe under the fixed bed biofilm reactor, thereby upflowing by air lift. By forming the waste water is automatically circulated from the fixed bed biofilm reactor into the aerobic tank, by operating in the dynamic characteristics of the fully mixed reactor as a whole to provide a high internal efficiency of the fixed bed biofilm reactor built-in internal circulation type complete mixing reactor By

In addition, the present invention provides a method of operating a reaction tank used for treating wastewater using a biological treatment process, by injecting excess air from an acid pipe under a fixed bed biofilm reactor built in an aerobic tank to form an upflow by air lift. Since the waste water is automatically circulated from the fixed bed biofilm reactor into the aeration tank, the operation method of the internal mixed cycle of the fixed bed biofilm reactor with the internal characteristics of the fixed bed biofilm reactor is characterized in that it is operated by the dynamic characteristics of the fully mixed reactor as a whole and exhibits high removal efficiency. By

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view of the entire reaction system of the present invention, (1) an aerobic tank, (2) a fixed bed biofilm reactor installed in a part of the space in the aerobic tank (1), (3) the fixed bed biofilm reactor (2) The carrier filled in the inside is shown. At this time, in order to separate and support the carrier filled in the fixed bed biofilm reactor 2 from the outside, a plastic or stainless steel net 4 is appropriately installed at the upper and lower portions. (5) and (6) show the diffuser which supplies air from the bottom of the said aeration tank 1, and below the fixed bed biofilm reactor 2, respectively. (7) is the influent and (8) is the final effluent and (9) represents the fluid flow circulating upstream in the fixed bed biofilm reactor and downstream in the aeration tank 1. (10) shows a complete mixing reactor, which is the overall reaction system of the present invention. The exhalation tank 1 does not need to fill the carrier when the fixed bed biofilm reactor 2 has good efficiency. However, the aeration tank 1 has a relatively large size and a submerged floating type so that sludge does not accumulate during the flow of the fluid even when it is filled. It is advisable to use a small amount (less than 50%, preferably less than 30%) of the volume of the complete mixer as possible to flow. For example, the size of the carrier in the aerobic tank is 20 mm or more, preferably 50 mm or more and the specific gravity of the carrier is 0.90-1.0, preferably 0.95-1.0 is good and the material of the carrier that satisfies these conditions Silver, polyethylene, polypropylene, and the like. The carrier 3 filled in the fixed bed biofilm reactor is required to be filled at least 30%, preferably at least 50% of the volume of the fixed bed biofilm reactor 2, and the size of the carrier 3 is to increase the removal efficiency. A submerged or fixed bed carrier of 50 mm or less, preferably 20 mm or less is filled. In this case, the fixed layer carrier 3 to be used is more preferably using a high-performance carrier containing activated carbon or clay-based inorganic material rather than a polymer material. The submerged carrier is designed to prevent sludge deposition in the fixed bed biofilm reactor 2 when the influent load is high so that the carrier is operated in the form of a fluidized bed flowed by excess aeration air. The amount of air supplied through the diffuser is less than 40% and not less than 60% to the diffusers 5 and 6, respectively, so that the diffuser 6 is supplied to the diffuser 6 under the fixed bed biofilm reactor 2 in excess. Thus, the flow rate of the fluid 9 circulated internally must be maintained at least two times, preferably at least five times the flow rate of the influent 7.

2A and 2B are a plan view and a side view of a complete mixed reaction tank in which a plurality of fixed bed biofilm reactors 2 are installed in a large sewage treatment system having a large size of the complete mixed reaction tank. The size of the fixed bed biofilm reactor 2 is approximately 1000 L ×. It is 1000W in size and is operated by installing several units in the complete mixing reactor. At this time, the position of the fixed bed biofilm reactor (2) may be located at an equidistant distance throughout the entire mixing reactor, or may be installed to one side, there is no problem in the internal circulation.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

A fixed bed biofilm reactor 2 having a size of 1700H × 700L × 800W was installed in a rectangular aerobic tank 1 having a size of 2000H × 1400L × 1000W, and a diffuser was placed under the exhalation tank 1 and below the fixed bed biofilm reactor 2, respectively. And (6) were installed to inject 20 l / min and 50 l / min of air into each of the diffusers. The rectangular exhalation tank 1 was filled with a submerged floating carrier, and a stainless steel mesh 4 was installed at a height of 300 mm and a height of 1700 mm from the bottom of the exhalation tank 1 in the fixed bed biofilm reactor 2. A 7 mm diameter, 10 mm long, polypropylene tubular carrier was filled to a height of 1400 mm. The water level of the aerobic tank 1 was kept at 1900 mm, and the influent sewage 7 was removed. The influent (7) was used sewage from the general apartment, and added to the soy sauce and detergent was added after adjusting the BOD and COD concentration of the influent (7). When the BOD, COD, and SS concentrations of the influent water 7 were maintained at 300, 250, and 350 ppm, respectively, and the inflow flow rate was introduced at 7 m 3 / day, the BOD, COD, and SS concentrations of the final effluent 8 after 4 months were The removal rates reached 92, 82, and 91%, respectively, at 25, 45, and 32 ppm, respectively. Even after 12 months of operation, no disturbance in the flow path due to sludge deposition in the fixed bed biofilm reactor 2 was observed.

Example 2

Landfill leachate was applied to the system to evaluate the treatment capacity. At this time, the aerobic tank 1 had a size of 1200H × 1000L × 600W, and the fixed bed biofilm reactor 2 was a carrier coated with activated carbon, zeolite, etc., 50% of the volume of the fixed bed biofilm reactor 2, The exhalation tank 1 was operated by filling a tubular submerged carrier with 30% of the volume of the exhalation tank 1. After microbial acclimatization, the COD of the influent (7) was 2,000 ppm and the COD of the effluent (8) was 200 ppm on average under normal operating conditions.

Example 3

In addition to the complete mixing reactor 10 as in Example 1, the same height as that of the complete mixing reactor 10 of Example 1, but with a volume of 1/2 volume (the size of the aerobic tank is 2000H × 1000L × 700W, the size of the fixed bed biofilm reactor is 1700H). (500 × 600 × 600 W) was further connected in series to perform a removal experiment. In the fixed bed biofilm reactor in the second complete mixing reactor, activated carbon, coke, steel slag, and bentonite were mixed in a polypropylene tube having a diameter of 7 mm × length of 10 mm and the carrier coated with an adhesive was coated with the fixed bed biofilm reactor volume. About 70% of the amount was filled, and the carrier in the same state as in Example 1 was filled in the aerobic tank. 5 l / min was injected into the diffuser at the bottom of the second aerobic tank, and 20 l / min was injected into the diffuser below the fixed bed biofilm reactor. When the concentration of COD, BOD, SS, and ammonium ions in the influent was maintained at 250, 350, 300, and 32 ppm, respectively, and the wastewater treated at 7 ㎥ / day, the concentrations of contaminants in the effluent were 25, 9, and 15, respectively. The removal rate reached 90, 97, 95 and 94%, respectively. In particular, 27.2 ppm of the ammonium ions were converted into nitrate and nitrite ions.

Example 4

In Example 3, when the BOD concentration of the influent (7) was increased to 400 ppm and the influent (7) flow rate was increased to 10 m 3 / day, the BOD concentration of the effluent (8) was 8-12 ppm, and the concentration of SS was filtered. It was then maintained at 5 ppm.

Example 5

As a similar system as in Example 3, the commercial wastewater treatment system operated by the standard activated sludge method for treating 40m3 / day household sewage has a BOD and SS concentration of 270 and 320 ppm of influent, respectively, and a concentration of effluent, respectively. All were operated at 60-80 ppm on the basis of. The sizes of the first and second aerobic tanks are 3700H × 3000L × 2500W and 3700H × 1500L × 2500W, respectively, and the size of the packed fixed bed biofilm reactors is all 3500H × 1000L × 1000W, and the four and second in the first aerobic tank are Two fixed-bed biofilm reactors were installed at equal intervals in an aerobic tank, and air was injected by installing an acid pipe under each fixed-bed biofilm reactor. Here, unlike Example 3, the carriers were not filled in the first and second aeration tanks, and each of the fixed bed biofilm reactors in each aerobic tank was filled with the same carrier as in Example 3 of each fixed bed biofilm reactor volume. About 60% filled. When the amount of return sludge from the settling tank to the anaerobic tank at the front end was maintained at 100% of the influent, the quality of the effluent was improved to 9 ppm and 8 ppm, respectively, after 3 months.

As described above, according to the present invention, the internal circulation type complete mixing reactor with a fixed bed biofilm reactor according to the present invention and a method for operating the same include an excessive amount of sludge accumulation in the carrier, which is a weak point of the fixed bed biofilm reactor, while using high efficiency removal characteristics in the fixed bed biofilm reactor. It is prevented by air aeration, so no backwashing is required.

In addition, the present invention is a relatively small amount compared to the reactor that does not use the fixed bed biofilm reactor by filling a small amount of the aerobic tank volume in the fixed bed biofilm reactor long in the fixed bed instead of filling the expensive microbial carrier with a thin layer in the aerobic tank. The use of air for aeration also has the advantage of facilitating the mixing of the oxygen solubility and the fluid.

In addition, the present invention increases the short hydraulic residence time which is a disadvantage of the fixed bed biofilm reactor and reduces sludge deposition in the fixed bed biofilm reactor even when the concentration load of the influent is very large.

In addition, the present invention is because the entire system is operated as a fully-mixed reactor due to the internal circulation of excess (preferably 5 times or more) compared to the influent, so the high load wastewater (eg For example, leachate, livestock wastewater, and high concentration wastewater can be treated.

In addition, the present invention is simple and easy to operate because only the excess of the supernatant of the completely mixed reaction tank is automatically returned to the inside of the fixed-bed biofilm reactor without the need for MLSS (Mixed Liquor Suspended Solid) adjustment.

Finally, the present invention can be easily installed in the fixed sludge biofilm reactor in the pre-installed activated sludge process, so that the conversion to the present reaction system can be easily performed.

Claims (7)

In the reaction tank used for the treatment of wastewater using a biological treatment process, a fixed bed biofilm reactor (2), which occupies some space in the aerobic tank (1), is installed and installed from the diffuser (6) below the fixed bed biofilm reactor (2). The excess air is injected to form an upflow (9) by air lift, so that the waste water is automatically circulated from the fixed bed biofilm reactor (2) into the aeration tank (1), thereby operating in the dynamic characteristics of the fully mixed reactor as a whole. Fixed cycle biofilm reactor built-in internal circulation complete mixing reactor (10), characterized by high removal efficiency. The method according to claim 1, wherein when the carrier is not filled or filled with a carrier, the tank is filled with less than 60% of the volume of the tank, and the carrier size is 20 mm or more, and the specific gravity is 0.90-1.0. An internal circulation complete mixing reactor (10) with a fixed bed biofilm reactor, characterized in that the flow of the downflow (9) in the aerobic tank (1) is smooth using a submerged fluid bed carrier. The method of claim 1, wherein the upper and lower portions of the fixed bed biofilm reactor 2 are blocked with a network 4 to fill the space between the two networks 4 with the carrier 3, and the volume of the filled layer is fixed to the fixed bed biofilm reactor (2). 2) 40% or more of the volume, the size of the carrier (3) 50 mm or less, characterized in that using a fixed bed biofilm reactor built-in internal circulation complete mixing reactor (10). The internal circulation type complete mixing reactor (10) according to claim 1, wherein a plurality of the fixed bed biofilm reactors (2) are installed in the aerobic tank (1). In the operation method of the reaction tank used for the treatment of wastewater using a biological treatment process, an excessive amount of air is injected from the diffuser (6) below the fixed bed biofilm reactor (2) built in the aerobic tank (1) so A fixed bed biofilm, characterized by forming a flow (9) to allow waste water to be automatically circulated from the fixed bed biofilm reactor (2) into the aerobic tank (1), thus operating at the same time as the overall dynamics of a fully mixed reactor to exhibit high removal efficiency. Operation method of the reactor internal internal circulation complete mixing reactor (10). 6. The internal circulation of a fixed bed biofilm reactor according to claim 5, wherein the excess air aeration in the fixed bed biofilm reactor 2 indicates high removal efficiency and prevents sludge accumulation in the carrier 3, thereby eliminating the need for backwashing. Operation method of the type complete mixing reactor (10). The internal circulating internally complete fixed bed biofilm reactor according to claim 5, wherein the internally circulated wastewater (9) is circulated in excess of the influent so that the entire system is operated as a fully mixed reactor, thereby allowing the treatment of high load wastewater. Operation method of the mixed reaction tank (10).