KR20020044193A - Anaerobic Reactor for Wastewater Treatment - Google Patents

Abstract

PURPOSE: An anaerobic reactor for treating wastewater is provided. The anaerobic reactor is based on an anaerobic filter having sludge bed. The anaerobic reactor is characterized in that gas generated from sludge bed is collected at the upper part of the sludge bed and by-passed out of the anaerobic reactor for preventing generation of turbulent flow at the upper part of the anaerobic reactor. Also suspended solid and microorganism floated from the sludge bed are collected and recycled to the lower part of the sludge bed for minimizing overflow of microorganism. CONSTITUTION: The anaerobic reactor comprises the following area: sludge bed area(A) for decomposing organics; gas collecting and by-passing area(B) that contain several gas collecting devices(30); microorganism collecting and recycling area(C), for collecting suspended solid and microorganism, packed with media being 120 m¬2/m¬3 of specific surface area; and supernatant water discharging area(D).

Description

Anaerobic Reactor for Wastewater Treatment

The present invention relates to an anaerobic wastewater treatment reactor, and specifically, in the reaction tank for treating the organic matter introduced by placing a sludge bed zone in which microorganisms are maintained at a high concentration under the reactor, the gas generated in the sludge bed zone is sludge bed zone. By collecting from the upper part of the reactor and bypassing the discharge (by-pass) to prevent the formation of turbulence in the upper part of the reactor, by collecting and returning the floating SS and microorganism in the microbial collection / transport area of the microorganisms that flow out of the reactor It relates to an anaerobic wastewater treatment reactor with a minimal amount.

Anaerobic wastewater treatment removes organic matter in wastewater by converting it into carbon dioxide and methane under anaerobic conditions, and has the advantage of keeping active microorganisms at a high concentration of 5,000 to 100,000 mg / l in the reactor and using the generated methane gas as fuel. There are advantages to it.

However, anaerobic wastewater treatment is a problem in which turbulence is formed in the reaction tank by rising gas, and SS or microorganisms with bubbles of generated gas are floated so that a large amount of microorganisms are leaked and measured as untreated organic matter. There is this.

Thus, attempts have been made to minimize the outflow of microorganisms while maintaining high concentrations of microorganisms in the reactors, which are roughly classified into anaerobic filter (AF) reactors and UASB (upflow anaerobic sludge blanket) reactors.

The AF reactor is a media (media) that allows microorganisms to adhere and grow in the reactor to keep the microorganisms at a high concentration and does not flow out. The media uses a large specific surface area to maximize the amount of microorganisms that grow and adhere.

The AF reactor has an upflow type and a downflow type depending on the flow of waste water, and there is a hybrid type having a filter installed only at the upper part.

Korean Patent Application No. 97-75848 (Ssangyong Yanghoe Co., Ltd.) is a ceramic filter material, Korean Patent Application No. 90-13436 (Hyundai Engineering Co., Ltd.) has a cross-flow filter material and US Patent No. 4,561,974 (Bernard et al.) U.S. Patent No. 4,294,694 (Coulthard) discloses plastic strip bundle media, respectively.

As an invention related to an AF reactor, U.S. Patent No. 4,561,974 (Bernard et al.) Discloses a reactor using three types of media, with a media having a specific surface area of 200 m 2 / m 3 or less at the bottom and a 200 m 2 specific surface at the top. It is characterized by installing a filter medium of more than / ㎥.

In Korean Patent Application No. 90-13436 (Hyundai Engineering Co., Ltd.), a sludge blanket layer is formed by installing nothing at the bottom, and the media having a specific surface area of 120 m 2 / m 3 or more and a bend angle of 55 to 65 ° at the upper part only. The installed wastewater treatment reactor is disclosed. The influent is treated as it passes through the sludge blanket layer and the microbial layer of the filter media in turn. It is characterized by the use of cross-flow media with a specific surface area of 120㎡ / ㎥ or more.

U.S. Patent No. 4,530,762 (Love) discloses an anaerobic reactor with a filter installed at the top and a large hood installed at the bottom of the filter area. The inflow water introduced into the lower part of the reactor is decomposed in the sludge layer formed in the lower part of the reactor, and gas is generated. The generated gas is collected in the hood together with the liquid, and then separated and removed from the gas separator installed outside the reactor, and the liquid is introduced into the reactor. Is returned. However, this requires a separate gas separator and the process is complicated, the gas rises to the top of the reaction tank has the disadvantage of causing turbulence.

U.S. Patent No. 4,676,906 (Crawford et al.) Discloses a wastewater treatment reactor in which a microorganism is emptied of suspended growth in the lower part and a thermoplastic ring is installed in the upper part so that the microorganism adheres and grows. It is claimed that the filter bed does not become clogged as it passes through and rises to the top of the reactor, creating vertical mixing and turbulence.

All of the upflow AF reactors are designed with a growth-growth concept and use a medium with a large specific surface area, and if it is operated for a long time, the filter layer is clogged and a drift phenomenon occurs. Therefore, the medium has to be exchanged every 2-5 years. have. In addition, there is a disadvantage that it is difficult to apply to the waste water with a high concentration of suspended solids, and there is a disadvantage that the floating SS is included in the effluent due to the turbulence formed by the air bubbles and flows out.

In addition, U.S. Patent No. 4,826,600 (Ely) and U.S. Patent No. 4,311,593 (Benjes et al.) Disclose downflow AF using media having a large specific surface area. Downflow AF uses carbon dioxide stripping. Since it is removed, there is an advantage that can reduce the requirement of sodium hydroxide (NaOH) for pH adjustment, but has a disadvantage of low processing efficiency.

UASB forms a sludge granules layer at the bottom of the reactor to remove the organic matter while the incoming wastewater passes through the granular sludge layer. A gas-solid separator (GSS) is installed at the top of the reactor. It is characterized by separating and settling the microorganism rising with the gas.

U.S. Patent No. 5,338,445 (Zumbragel et al.) Discloses a UASB reactor in which multiple stages of gas collection devices are installed in the reactor. US Patent No. 4,622,147 (Vellinga) discloses a UASB reactor using three layers of gas collection hoods. However, even if a gas collecting hood is installed, SS and microorganisms raised to the upper part of the reaction tank are not likely to be returned to the lower part of the reaction tank but are likely to be mixed with the effluent and flow out.

U.S. Patent No. 4,632,758 (Whittle) and U.S. Patent No. 5,006,249 (Green, etc.) disclose a method of separating and removing gas using a degassing device installed outside the UASB reactor. Since the reactor uses a separate solid-liquid separator, the apparatus is complicated, and the problem of SS and microorganisms rising to the upper part of the reactor mixed with the effluent remains and remains.

U.S. Patent No. 4,315,823 (Witt et al.) Discloses a method for removing gas outside the reactor, precipitating solids and returning it to the reactor, which is particularly suitable for wastewaters with COD 2,000 mg / l or more (5,000-6,000 mg / l). It is claimed.

However, the UASB reactor may have no granulation of sludge depending on the characteristics of the influent wastewater, and it is difficult to apply to wastewater containing a lot of solids. In addition, since the gas and SS are separated from the effluent using only a gas-solid separator (GSS) without a separate solid-liquid separation facility on the reaction tank, solid-liquid separation and microbial retention are not efficient.

As described above, all the anaerobic reactors to date are reactors for high concentration wastewater treatment in consideration of deposition growth or granular sludge formation, and the removal rate of organic matter from the plant is only about 85%.

It is an object of the present invention to provide an anaerobic reactor capable of discharging effluent comparable to aerobic treatment only by anaerobic treatment of various industrial wastewater and sewage of medium to low concentrations, as well as high concentrations.

1 is a schematic diagram of an anaerobic wastewater treatment reactor of the present invention.

2A is a front view of a gas collection / bypass device.

2B is a side view of the gas collection / bypass device.

3 is a layout view of a wastewater conveying pipe.

4 is a layout view of the influent distribution pipe.

5 is a detailed view of the wastewater inlet pipe and the distribution pipe connection.

FIG. 6 is the COD of the effluent when the dairy wastewater having a COD of 1,000 mg / l was treated at a maximum loading rate of 8 kgCOD / m 3 / day.

7 is the COD of the effluent water when the ethanol wastewater of 8,000 mg / L COD was treated at the maximum load rate of 16 kg COD / m 3 / day.

Explanation of symbols on the main parts of the drawings

10: reaction vessel 20: microorganism collecting / conveying device

21: Microbial trapping / conveying device disposed on the side of gas trapping / bypassing device

30: gas collection / bypass device 40: wastewater inlet pipe

41: outlet pipe 42: gas bypass pipe

43: wastewater return pipe 44: sludge return pipe

45: gas outlet pipe 46: influent distribution pipe

47: opening and shutting plug 48: distribution pipe hole

50: wastewater injection pump 51: return pump

A: Sludge Bed Area B: Gas Capture / Bypass Area

C: Microbial capture / convey zone D: Effluent capture zone

In the anaerobic reactor of the present invention, a sludge bed region A in which a sludge layer is formed from the bottom of the reactor, and a gas collection / bypass region provided with a gas collecting device for trapping and bypassing the gas rising from the sludge bed region ( B), a microbial capture / conveying zone (C) provided with a medium or gradient plate settling basin for collecting and conveying the rising SS and microorganisms, and an effluent discharge zone (D) in which the effluent flows out in a laminar flow state.

A characteristic difference of the present invention compared to the prior art is that the gas generated in the sludge bed region on the upper part of the sludge bed region is bypassed and discharged out of the reactor to prevent turbulence from forming in the upper portion of the reactor. A collection / bypass zone (B) and a gas collection / bypass zone (B) are placed at the top of the SS and the microbial capture / transport zone (C) to return the microorganisms to the amount of microorganisms flowing out of the reactor. Minimize.

Comparing the present invention with the upflow type AF, the gas collection / bypass zone (B) exists and the purpose of conveying the floating SS and the microorganisms to the lower part of the reactor rather than installing the media for attaching and growing the microorganisms. The difference is that the installation, compared with the UASB reactor, allows the normal treatment without the formation of granular sludge in the sludge bed area, the use of a more efficient gas-liquid-high separator than UASB, and the return of the rising SS and microorganisms. The microbial capture / convey zone (C) is different.

Hereinafter, the configuration of the present invention will be described in more detail with reference to the drawings while following the flow of waste water.

Influent water is introduced into the wastewater inlet pipe 40 by the wastewater infusion pump 50 and introduced into the lower part of the reaction tank 10 through the inlet water distribution pipe 46 so that the sludge bed area having the suspended sludge layer or the granular sludge layer A exists. ), 70-90% of organic matter is converted to methane and carbon dioxide.

Whether the sludge layer formed in the sludge bed area A is suspended sludge or granular sludge is determined by the characteristics of the inflow wastewater. However, unlike the UASB reactor, the anaerobic reactor of the present invention is capable of normal treatment of wastewater without generating granular sludge.

On the other hand, methane and carbon dioxide generated in the sludge bed area (A) rises in the form of bubbles and is collected by the gas collecting device 30 in the gas collection / bypass area (B) and discharged. The total area of the gas collecting device installed in the gas collecting / bypass area B is 50 to 200% of the reactor floor area.

2 is a detailed view of the gas collection / bypass device 30.

The gas collecting / bypassing device 30 may be installed in one or several stages, and may be made of coated iron plate, stainless steel, or synthetic resin. (theta) takes the value of 20-90 degrees.

On the side of the gas collecting device 30, an inclined plate sedimentation basin or a cross flow media 21 is installed to primarily suppress the rise of SS and microorganisms. SS attached to microorganisms and microorganisms rise When the bump hits the swash plate or cross flow media, bubbles are released and bubbles rise, and SS is precipitated again, so that the SS and microorganisms leaked out are significantly reduced than other reactors.

As the media installed on the side of the gas collection / bypass apparatus 30, it is preferable to use a cross flow media having an inclination angle of 20 m to 80 ° with a specific surface area of 102 m 2 / m 3 or less.

In spite of the presence of media or slant plate settling basin installed on the side of the gas collecting / bypassing device 30, the microorganisms and SS that have risen together with the wastewater through the gas collecting / bypassing area (B) are collected in the upper microbial collecting / conveying area. In (C), it is collected in a cross-flow filter medium having a specific surface area of 120 m 2 / m 3 or less installed for solid-liquid separation, or a slant plate settling basin, and is conveyed back to the sludge bed area A through the sludge conveying pipe 44.

On the other hand, the gas generated in the sludge bed area A is collected in the gas collection / bypass area B and sent to the combustion apparatus or the storage tank.

In the microorganism collecting / conveying area (C), the floating microorganisms and SS are collected and returned to the lower part of the reactor by the sludge conveying pipe 44, and organic matter is further removed from the microbial layer formed on the surface of the filter medium. In the microbial collection / conveying zone (C), a sloped sedimentation basin having excellent SS separation performance or media having a specific surface area of 120 m 2 / m 3 or less are installed.

When conveyance is necessary, it conveys to the sludge bed area | region A of the lower part of a reaction tank through the wastewater conveyance pipe 43 installed in the lower part or upper part of microorganism collection / conveyance area C.

3 is a layout view of a conveying pipe.

The conveyance pipe 43 is installed in the lower end Y or the upper end X of the microorganism collection / conveying area C. In order to prevent the formation of turbulent flow in the outflow water collecting zone (D), it is preferable to install at the bottom (Y). When installed in the top (X) is because turbulence is formed in the runoff collection area (D) because the microorganisms can be leaked.

In the effluent collection area D, the effluent flows out in a laminar flow state. Since air bubbles are removed in the gas capture / bypass area (B) and most of the SS and microorganisms are removed in the microbial capture / transport area (C), the flow can be maintained in a laminar flow, thus effluent is good. Water quality can be maintained.

4 is a layout view of the influent distribution pipe 46.

The hole 48 of the distribution pipe is preferably lowered. In addition, as shown, both end portions of the distribution pipe 46 may protrude out of the reaction tank and the opening and closing plugs 47 may be installed at both ends of the distribution pipe 46 to clean in the M or N direction.

5 is a detailed view of the connection portion of the wastewater inlet pipe 40 and the distribution pipe 46.

The reaction tank of the present invention targets BOD 300 to 150,000 mg / l wastewater, and the organic matter loading rate is preferably 4 to 30 kgCOD / m 3 / day.

The construction of the present invention will become more apparent from the following examples.

<Example 1>

A. Reactor and Sample Wastewater

In the 10-L reactor shown in FIG. 1, a dairy wastewater having a COD of 1,000 mg / L (700 mg BOD / L) was used as the sample waste water. In the microbial collection / recovery area (C), a media with a specific surface area of 108 m 2 / m 3 was installed, and a cross flow media with a specific surface area of 102 m 2 / m 3 was installed on the side of the gas collection / bypass device.

B. Experiment

After 140 days of operation, the organic loading rate (OLR) was doubled by doubling the flow rate at the 45th, 66th and 84th days of operation, and after 84 days. It was kept at 8 kg COD / m 3 / day.

The COD of the effluent is shown in FIG. 6. When the loading rate of organic matter was doubled (ie 45 days, 66 days, 84 days after the start of operation), the COD of the effluent was temporarily increased (upset), but returned to normal within 3 to 4 days. Except that the COD of the effluent was increased in the short term whenever the organic loading rate is increased, the reactor of the present invention shows that the average COD of the effluent is 73 mgCOD / L regardless of the loading rate at the organic loading rate of 1 to 8 kg COD / ㎥ / day. The average removal rate was 92.7%. [BOD averaged 43mg / l (20-68mg / l) with an average removal rate of 94%]

According to the reactor of the present invention, unlike the conventional high rate anaerobic reactor was mainly applicable only to high concentration wastewater, it can be seen that high organic matter removal rate can be obtained even for wastewater of medium and low concentrations.

<Example 2>

A. Reactor and Sample Wastewater

Using the reactor used in Example 1, wastewater having a COD of 8,000 mg / L (5,500 mg BOD / L) was used as a sample wastewater.

B. Experiment

The operation was performed for 140 days, and the organic matter loading rate was doubled by doubling the flow rate at the time of 40 days, 60 days, and 80 days after the start of operation. After 80 days, the load was continuously maintained at 16 kg COD / ㎥ / day.

The COD of the effluent is shown in FIG. 7. When the loading rate of organic matter was doubled (ie 40 days, 60 days, 80 days after the start of operation), the COD of the effluent was temporarily increased (upset), but returned to normal within 3 to 4 days. Except that the COD of the effluent was increased in the short term whenever the organic loading rate was increased (upset), the reactor of the present invention had an average COD of the effluent regardless of the loading rate at a loading rate of 2 to 16 kg COD / m3 / day. / l average removal rate was 91.4%. [BOD averaged 203mg / l (120 ~ 292mg / l) and the average removal rate was 96.3%]

As can be seen in Example 1, it can be seen that according to the reactor of the present invention, unlike the conventional high rate anaerobic reactor, which was mainly applicable to only high concentration wastewater, it is possible to obtain a high organic matter removal rate for medium / low concentration wastewater.

The anaerobic wastewater treatment tank of the present invention can be widely applied to a low concentration wastewater having a BOD of 300 mg / l to a high concentration wastewater of 150,000 mg / l, unlike the existing high rate anaerobic reactor, which was mainly used only for high concentration wastewater treatment.

In addition, by discharging methane and carbon dioxide to the outside by using a gas collection / bypass device, the amount of dissolved carbon dioxide is also reduced, so that the amount of sodium hydroxide (NaOH) required to adjust the pH of the reactor can be reduced.

Claims (7)

Sludge bed area (A) in which sludge layer is formed sequentially from the bottom of the reactor to decompose organic matter, and gas collection / bypass area in which multiple stages of gas collecting devices for trapping and bypassing rising gas in the sludge bed area are installed. B), a microbial capture / conveying zone (C) equipped with a cross flow media having a specific surface area of 120 m 2 / m 3 or less for collecting and transporting rising SS and microorganisms, and an effluent discharge area for effluent flowing in a laminar flow state (D) Anaerobic wastewater treatment reactor consisting of The anaerobic wastewater treatment tank according to claim 1, wherein the trapping / transferring of SS and microorganisms rising in the microbial collection / transport zone (C) is an inclined plate sedimentation basin. The anaerobic wastewater treatment reactor according to claim 1 or 2, wherein the microbial collection / conveying zone (C) is at least one stage. The anaerobic wastewater treatment reactor according to claim 1 or 2, wherein a sludge conveying pipe is installed in a wastewater inflow pipe at a lower part of the microbial collection / conveying area (C). The anaerobic wastewater treatment tank according to claim 1 or 2, wherein the wastewater conveying pipe is installed in the lower portion of the sludge bed region (A) at the upper or lower portion of the microbial collecting / conveying region (C). The anaerobic wastewater treatment reactor according to claim 1 or 2, wherein the total surface area of the gas collection device installed in the gas collection / bypass zone (B) is 50 to 200% of the reactor floor area. The anaerobic wastewater according to claim 1 or 2, wherein an inclined plate settling basin or a cross-flow media having a specific surface area of 120 m 2 / m 3 or less is provided on a side of the gas collecting device installed in the gas collecting / bypass area B. Treatment reactor.