KR19980084220A - High concentration organic wastewater treatment method and apparatus - Google Patents

Abstract

The high concentration of organic wastewater is introduced into the biofilm filter, and the organic material is decomposed using the microorganisms in the flotation media present in the biofilm filter described above, the organic material is removed, recycled back to the biofilm filter, and overgrown in the biofilm filter. One sludge decomposes organic matter in a high concentration of organic wastewater using a process and a device for backwashing the water in a treatment tank using a backwash pump and then solid-liquid separation in a sludge separator.

Description

High concentration organic wastewater treatment method and apparatus

[Industrial use]

The present invention relates to a wastewater treatment method and apparatus, and more particularly, to an economical biological treatment method and apparatus that can effectively remove organic impurities present in high concentration organic wastewater.

[Prior art]

Wastewater is generated through human activities and various industrial activities, and then enters various water sources that humans use for various purposes through various channels. If the wastewater is discharged to the natural ecosystem without treatment, many adverse effects such as causing various diseases will be caused to humans. There are several physicochemical and biological methods of treatment and disposal of waste water. While the physicochemical method is expensive and has the disadvantage of reprocessing or disposal of the treated product, the biological treatment method decomposes or stabilizes a large amount of organic components in the form of carbon dioxide or generates methane gas (CH ₄ ). To remove organics in the wastewater, thereby relatively reducing the amount of product produced after the treatment. Biological treatment methods mainly use microorganisms to decompose, detoxify, and separate contaminants in wastewater, and microorganisms involved in the method include bacteria, fungi, algae, protozoa, and some lower animals.

Biological treatment is mainly used for secondary treatment of urban sewage, factory wastewater containing organic matter and sludge produced therefrom, and is the most widely used wastewater treatment method in the world due to relatively low cost and various processes. Biological treatment methods are divided into aerobic treatment method and anaerobic treatment method according to the use of oxygen, and aerobic treatment methods include activated sludge method, water spraying method, rotating disc method, and oxidation paper method, and anaerobic digestion method and septic tank. Law, etc. In these treatments, the microorganisms live floc evenly in the wastewater and either float or adhere to a suitable surface.

The biological process of wastewater is as follows. First, prior to biological treatment of wastewater, it is subjected to primary treatment, which is a process of sedimenting and physically separating sedimentable substances in the wastewater. The purpose of this treatment is to remove incoming solids, such as waste water, or suspended solids (SS), usually settling for 1-2 hours in the primary settling tank or primary clarifier. Let's do it. If anaerobic metabolism by anaerobic microorganisms occurs at the bottom of the sedimentation basin, gases such as nitrogen gas may be generated and the sediments may float and re-introduce into the wastewater. do. The sedimentation basin also serves as a floating tank, and grease, which floats to the surface due to its specific gravity lower than the waste water, is removed using a surface skimmer. Air may be injected into the wastewater or vacuumed for smoother injury. Primary treatment does not remove dissolved organics. In other words, organic pollutants (BOD) can be removed by 20 ~ 60% of the wastewater, depending on various factors such as solids content and primary treatment methods. BOD removal efficiency Wastewater after primary treatment enters secondary treatment, a biological treatment.

As described above, the secondary treatment is a method of biologically treating organic contaminants present in raw water or wastewater, and a method of removing organic matter decomposable by living organisms using microorganisms, plants, and the like is generally used. Among them, the activated sludge method using activated sludge is widely used. This method uses the principle that when the air is injected into the wastewater containing organic matter in the aeration tank, the organic matter is decomposed into carbon dioxide and water by the aerobic metabolism of microorganisms present in the wastewater, and the organic matter in the wastewater is increased. It is a method of decomposition and removal. At this time, microorganisms form flocs with a diameter of 0.1 to 1 mm in the wastewater, and bacteria forming mucus are involved in the floc formation, and various organic and inorganic substances in the wastewater are adsorbed onto the flocs. Once the wastewater is collected in the original wastewater storage tank, the inflow water from which the suspended solids are easily removed from the screen tank is stored in the flow storage tank and introduced into the aeration tank. In the aeration tank, aerobic microorganisms are aerated for a certain period of time in the flow state to remove organic matter in the waste water by oxidative decomposition, and then the mixed liquid in the aeration tank is moved to the final sedimentation tank to stop the aeration. (Sludge) is separated. After separation, the supernatant is finally disinfected and discharged or further treated. Some of the precipitated sludge is returned to the aeration tank as a return sludge for reuse of the activated sludge in the aeration tank, and the other part is dewatered and disposed of as a surplus sludge. At this time, the activated sludge, which plays a key role in the biological treatment device, is a reactor made of a concrete structure, which contains a mass of microorganisms called activated sludge, and these microorganisms multiply by using dissolved oxygen dissolved in the wastewater and organic contaminants. Is used as a nutrient to decompose and remove organic contaminants.

The activated sludge in the activated sludge process has a limited degree of microorganisms, and the activated sludge occupies a lot of space. The agglomerates of microorganisms grown in the activated sludge are settled and discharged from the sedimentation tank, which is a subsequent process. There is a problem that takes up space. In addition, when activated sludge is loaded with organic contaminants at high loads or when the load fluctuations of the influent wastewater are severe, the decomposition of organic matters and sludge deposition do not occur properly, resulting in poor treatment efficiency and exposure to the outside. have.

In addition, when toxic substances are present in the wastewater, most of the microorganisms in the sludge die and the treatment efficiency is drastically reduced. If there is a non-degradable substance in the waste water that cannot be decomposed by microorganisms, it can be discharged as it is. In addition, if the organic matter is contained in high concentrations in the wastewater, a large amount of dilution water should be generally used for biological treatment of high concentration organic wastewater because of the toxicity of the organic matter to the microorganisms and the limitation of oxygen supply necessary for microbial growth. do. For example, if you want to treat livestock wastewater or food wastewater with BOD 20,000mg / ℓ by activated sludge method, dilution of 50-100 times is necessary according to the characteristics of wastewater. As the dilution drainage increases, the size of the treatment plant increases proportionally, and the actual investment costs and the site area become too large, and thus the actual treatment is difficult when high concentration wastewater is generated.

As one method for coping with such a reality, there is a biofilm filtration method. The biofilm filtration method is filled with a filter medium having excellent characteristics for microorganisms to grow inside the biofilm filter and accumulates a large amount of microorganisms in the biofilm filter to treat waste and wastewater, so the treatment performance is much better than that of the activated sludge process. Therefore, the biofilm filtration method is capable of advanced treatment to a much smaller scale treatment facility, and this method has recently been spreading.

Biofilm filtration is the removal of dissolved or suspended organic matter in the wastewater by the biofilm attached to the surface of the solid filter media, and microorganisms and welfare animals live in the biofilm. In general, the biofilm method has a thickness of 1 to 2 mm or more and a microorganism shows rapid growth near the surface of the membrane and actively decomposes the organic matter in the water, but the lower part of the surface has a low organic content because the organic matter does not penetrate well. In addition, the dissolved oxygen is also insufficient to form an anaerobic layer. The formation of an anaerobic layer results in a decrease in treatment efficiency and in some cases the adhesion of microorganisms is weakened. Biofilm filtration has been developed to compensate for the above-mentioned disadvantages, unlike the general biofilm, the thickness of the biofilm is only 0.1 ~ 0.2㎜ can maintain the entire membrane layer aerobic. However, biofilm filtration requires backwashing of the biofilm filter. For backwashing, up to 20% of the treated water must be used as a backwash tank, and clogging of the filter when the backwash of the influent biofilm filter is not properly performed ) Occurs and there is a problem that causes a decrease in processing efficiency.

The present invention has been made to solve the above-mentioned problems of the prior art, the object of the present invention is to reduce the cost of a large amount of dilution water when the treatment of high concentration organic wastewater is reduced and the environment It is to provide a high concentration organic wastewater treatment apparatus and method that can solve the water shortage problem which is a serious problem caused by pollution problems.

1 is a cross-sectional view schematically showing a high concentration organic wastewater biological treatment apparatus according to the present invention.

Explanation of symbols on the main parts of the drawings

11 Supply Pump 13 Gas-liquid Mixer 15 Biofilm Filter

17 Floating media layer 19 Strainer 21 Treatment tank

23 Backwash pump25 Circulation pump27 Sludge separator

[Means for solving the problem]

The present invention has the following configuration to achieve the above object of the present invention.

In the present invention, the step of introducing the waste water into the biofilm filter (biofilter: 15), using the microorganisms in the flotation layer 17 of the organic material of the introduced waste water in the biofilm filter (15) It provides a biological treatment method of the waste water, including the step of decomposing and recycling the treated water from which the organic material has been removed back to the biofilm filter (15).

The sludge that has been excessively grown in the biofilm filter 15 after the process of recycling the treated water further includes a step of solid-liquid separation in the sludge separator after backwashing the water in the treated water tank 21 using the backwash pump 23. desirable.

It is preferable that the circulation ratio of the said treated water is 0.5 to 200 times, and it is preferable to recycle the treated water while diluting and supplying the waste water.

In addition, when the specific gravity of the flotation filter 17 is greater than 1, it is preferable to introduce the wastewater into the biofilm filter 15 from the top downward.

In addition, it is preferable to supply pure oxygen or air into the biofilm filter 15, and to increase the oxygen dissolution rate for maximizing the decomposition activity of the microorganism, the biofilm filter 15 is preferably operated under a pressure of 1 to 3 kg / cm 2 G. Do. At this time, air or pure oxygen can be mixed and dissolved with the waste water using a gas-liquid mixer (static mixer) 13 and then mixed with the biofilm filter. In particular, when pure oxygen is supplied instead of air to give a pressure of 1 to 3 kg / cm 2 G, sufficient oxygen is dissolved in water and mixed with waste water, and then injected into a biofilm filter to decompose organic pollutants. Is maximized. When operating under a pressure of 1 to 3 kg / cm 2 G, the oxygen dissolution rate in the method according to the present invention is compared with the oxygen dissolution rate in the activated sludge method.

TABLE 1

Pressure (㎏ / ㎠) The present invention Activated sludge method 0 48 10 One 96 20 2 144 30 3 192 40

In the present invention, the feed pump 11 for introducing the waste water into the biofilm filter 15 and the floating filter 17 are floated therein, and the microorganisms are attached and grow through the feed pump 11. A circulating pump for introducing the biofilm filter 15 which decomposes the organic matter in the introduced wastewater and wastewater, and the highly treated water flowing out of the biofilm filter 15 into the biofilm filter 15 while joining the wastewater with the wastewater. Provided is a biological treatment apparatus for sewage and wastewater comprising (25).

The present invention also preferably further comprises a device for supplying pure oxygen or air into the biofilm filter 15.

The biofilm filter 15 is preferably open or closed and preferably operated under a pressure of 1 to 3 kg / cm 2.

1 is a cross-sectional view schematically showing a high concentration organic wastewater biological treatment apparatus according to the present invention.

The biofilm filter 15, which is a biological treatment device of the present invention, is filled with a flocculation filter layer 17 which provides a surface on which microorganisms can grow and is attached. Purification is performed while passing through the media layer. The strainer 19 is installed at a predetermined interval so that the filter medium does not pass through the filter medium and passes through the purified water, and the water passing through the biofilm filter is sent to the next process or stored in the treatment tank 21 or disinfecting tank. Finally discharged via

On the other hand, the fine sludge contained in the microbial sludge and inflow water grown in the biofilm filter (15), but stuck to the biofilm filter (15) by the filtration function of the biofilm filter (15) using a backwash pump (23) By pouring a certain amount of water from the upper portion of the biofilm filter 15 to the lower portion of the biofilm filter 15 at a high speed, the layer of floating media 17 is rinsed and periodically washed and then discharged to the outside. Due to the particularity of the media used, only 5% of the treated water is used for backwashing, and the backwashing flow rate is set appropriately so that a blockage of the filter does not occur.

In addition, the present invention can be installed by connecting several biofilm filters in series or in parallel according to the target value of the BOD to be treated.

As described above, the technical core of the present invention is to apply the excellent performance of the biofilm filtration method to treat highly concentrated organic wastewater without using a separate dilution water while recycling highly treated water.

In the biological treatment device, when the specific gravity of the floating filter 17 in the biofilm filter 15 is greater than 1, the wastewater is introduced into the downflow and the treated water is recycled. The biofilm filter 15 can be open or closed and oxygen can be supplied using both pure oxygen and air.

The present invention not only forms an aerobic film as thin as 0.1 mm on the surface of the media, but also maintains the aerobic layer up to the media surface by using pure oxygen to completely solve the disadvantages of the conventional biofilm method.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

EXAMPLE

Example 1

Purification experiments were performed on a high concentration organic wastewater of 20,000 mg / L BOD using a treatment apparatus having a biofilm filter 15 having the structure shown in FIG. 1 and the results are shown in Table 2 below.

TABLE 2

Wastewater BOD (mg / l) Circulation cost (circulating water / raw wastewater) Treated water BOD (mg / l) 20,000 50 100 20,000 100 45 20,000 150 30 20,000 200 20

As can be seen in Table 1, when the concentration of the raw wastewater BOD is constant, the concentration of the treated water BOD gradually decreases within the range of 100 mg / l or less as the circulation ratio increases, and is very stable up to the concentration of 20 mg / l. Was processed.

Example 2

Purification experiments were performed on livestock wastewaters of BOD 5,000 mg / L, 10,000 mg / L and 15,000 mg / L using a treatment apparatus having a biofilm filter 15 having the structure shown in FIG. It is shown in Table 3.

TABLE 3

Wastewater BOD (mg / l) Circulation cost (circulating water / raw wastewater) Treated water BOD (mg / l) 15,000 50 45 10,000 50 35 5,000 50 20

As can be seen from Table 2, the treated water BOD concentration was stably treated at a concentration of 20 mg / L to 45 mg / L as a result of the treatment using the apparatus of the present invention.

The treatment of high concentration organic wastewater does not require a large amount of investment compared to the conventional method because the treatment facility is not as large as in the conventional case, and it has the advantage of having a small site area and requires no extra dilution water. At the same time, it is very helpful in solving the water shortage problem, which is a serious problem.

Claims (11)

Introducing wastewater into the biofilm filter; Decomposing the organic material of the introduced sewage / wastewater using microorganisms in the flotation layer present in the biofilm filter; And Recycling the treated water from which the organic material has been removed to the biofilm filter; Biological treatment method of wastewater containing. The wastewater according to claim 1, further comprising a step of solid-liquid separation of the sludge that has been excessively grown in the biofilm filter after the step of recycling the treated water using a backwash pump, followed by solid-liquid separation in the sludge separator. Method of biological treatment. The biological treatment method of wastewater according to claim 1, wherein the circulation ratio of the treated water is 0.5 to 200 times. The biological treatment method of wastewater according to claim 1, wherein the treated water is recycled while partially diluting and supplying the wastewater. The biological treatment method of wastewater according to claim 1, wherein when the specific gravity of the flotation medium is greater than 1, the wastewater is introduced into the biofilm filter from the top to the downstream. The biological treatment method according to claim 1, wherein pure oxygen or air is supplied into the biofilm filter. The biological treatment apparatus of claim 1, wherein the biofilm filter is operated under a pressure of 1 to 3 kg / cm 2. A feed pump for introducing the wastewater into the biofilm filter; A biofilm filter which floats and fills the floating media therein, and decomposes organic matter in the wastewater introduced through the feed pump while the microorganisms are attached and grown; A circulating pump for introducing the highly treated water flowing out of the biofilm filter into the biofilm filter while joining the wastewater and the wastewater; Biological wastewater treatment device containing. 9. The biological treatment device of claim 8, further comprising a device for supplying pure oxygen or air into the biofilm filter. The biological treatment device of claim 8, wherein the biofilm filter is open or closed. The biological treatment apparatus according to claim 8, wherein the biofilm filter is operated under a pressure of 1 to 3 kg / cm 2.