KR0168827B1 - Method for purifying organic waste water - Google Patents

Abstract

The present invention is a purifying method for purifying water environment by first treating biological wastewater, human wastewater, domestic wastewater, and other industrial wastewater, which account for more than 60% of water pollution, and then performing physicochemical treatment secondarily. In particular, the present invention relates to a method for purifying organic wastewater using a microbubble flotation apparatus or an ultrafiltration membrane apparatus.

Pretreatment step including debris removal device (1), sand removal device (2), storage tank (3) and microbubble flotation device (4), and biological treatment step including a bioreactor (5) and microbubble flotation device (6) And a post-treatment step including an ozone contacting tank 8 having a ozone generating device 7 and a microbubble flotation device 9, and a sludge storage tank 10, a coagulation tank 11, and a dehydrator 12. It consists of a flocculation, dehydration process for dewatering the sludge obtained from the microbubble flotation device 6 installed in the biological treatment step and the microbubble flotation device 9 installed in the post-treatment step.

By applying such microbubble flotation device or ultrafiltration membrane device, BOD load reduction, prevention of blockage of pipes, prevention of abrasion of pumps, increase of oxygen dissolution efficiency in bioreactors, prevention of effective capacity erosion of various crude volumes, high concentration of MLSS concentration The need for maintenance, elimination of the use of chemical coagulants in the iron salt system, and the adoption of a continuous treatment method greatly reduce facility and maintenance costs, and at the same time maximize the purification efficiency.

Description

How to Clean Organic Wastewater

1 is a process chart for explaining the conventional method.

2 is a process diagram of the method according to the invention.

3 is a schematic configuration diagram of the microbubble floating apparatus extracted from FIG.

Figure 4 is a cross-sectional configuration of the ultrafiltration membrane device according to another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: debris removal device 2: debris device

3: storage tank 4,6,9: microbubble flotation device

5: bioreactor 7: ozone generator

8: ozone contact tank 10: sludge storage tank

11: coagulation tank 12: dehydrator

20: floating tank 21: pressurized pump

22: fine bubble generator 23: floating sludge removal device

30: ultrafiltration membrane device 31: membrane

32: inlet 33,34: outlet

The present invention is a purifying method for purifying water environment by first treating biological wastewater, human wastewater, domestic wastewater, and other industrial wastewater, which account for more than 60% of water pollution, and then performing physicochemical treatment secondarily. In particular, by using a microbubble flotation device or ultrafiltration membrane device to improve the purification efficiency in the biological treatment process, it is possible to adopt the continuous treatment method can solve all the problems that are followed in the batch treatment method, the entire facility The present invention relates to a method for the purification of organic wastewater, in which capacity is reduced and maintenance costs are greatly reduced.

Conventional methods for treating organic wastewater have largely been made of standard activated slotting methods or variations thereof.

For example, in the case of livestock wastewater or manure treatment by the activated sludge method, various contaminants in the collected wastewater are removed, and the liquid is homogenized in a storage tank, the pH is adjusted as needed, and diluted by adding 10-20 times of dilution water. It is activated by the operation of aerobic bacteria group by the blower, and it is transferred to the settling tank and left to settle naturally. The separated symbolic water is sterilized and discharged, and the precipitate is concentrated and dehydrated to be landfilled or incinerated.

However, this method is difficult to carry out where there is no water source because it adds a large amount of dilution water to organic sewage, and the total sewage capacity according to the dilution water is increased, and the facilities such as aeration tanks and sedimentation tanks are enlarged, and pumping and aeration There are several problems, such as increased power costs for maintenance, maintenance costs and operating costs, as well as the need for highly skilled skills in maintenance and the discharge of incompletely treated water.

In consideration of all the problems of the activated sludge method, the patented technology of the cause (Patent No. 33531) is a high-quality organic fertilizer suitable for agricultural use by completely separating liquid without adding a large amount of dilution water for organic sewage treatment. A purification method has been proposed that allows for the production of water and the recycling of industrially separated separations that meet the water quality standards.

This is briefly described based on FIG. 1 as follows.

According to FIG. 1, the organic wastewater includes pretreatment, supercorrosion treatment, flocculation treatment and post treatment.

In the pretreatment stage of organic sewage, sand is removed from the sedimentation tank, and the contaminants contained in the organic sewage are removed using a drum screen and a screw press, and then temporarily stored in the storage tank to homogenize the liquid.

In the super-corrosion treatment step, the organic sewage transferred from the storage tank is put into a liquid corrosion tank equipped with an aeration device, and the air is supplied to the blower to supply an appropriate amount of air. Allow the suspension to form.

In the coagulation treatment step, the suspension is transferred from the mixing tank to the coagulation reaction tank and coagulated with the organic polymer coagulant.

At this time, if necessary, the pH is adjusted to 9-10 with a pH adjuster (NaOH) or the like, and then a predetermined amount of an inorganic coagulant such as ferric chloride (Fecl ₃ ) is added to perform solid-liquid separation near PH 4.0-4.5. That is, the dehydrated cake and the desorption solution are obtained by dehydrating the agglomerated solids by a dehydrator.

In the post-treatment step, the pH control agent (NaOH) is added to the desorption liquid, and the microfiltration device is passed through to remove the solid sludge, which is transferred to the treatment tank for 3-4 hours retention and the neutral symbol water obtained at this time is activated carbon adsorption. Refining by using the device and transfer to the sterilization tank to be discharged after sterilization treatment.

At this time, a part of the supernatant water is transferred to the water tank for reuse as the washing water of the dehydrator and the small amount of concentrated sludge is returned to the mixing tank.

However, the method of purifying in such a step has the following problems.

In other words, the size of the contaminants that can be removed by the mechanical screen in the pretreatment step is about 2 mm or more, and it is impossible to remove even smaller colloidal suspended particles. Thus, the removal rate of BOD by the removal of the contaminants in the pretreatment is impossible. Is only about 5-10%, and the function of pretreatment is only the effect of preventing the blockage of pipes in the subsequent process and preventing the wear of pumps by removing sand and contaminants, and reducing the subsequent BOD load. Is almost unexpected.

In addition, since the inflow properties change depending on the season in the biological treatment process, that is, the superbiodegradation process, the overload condition is inevitable when the pretreatment process does not reduce the load to some extent. There is a pedan that affects the effluent.

In addition, in the second chemically coagulated treatment step, the use of inorganic coagulants such as ferric chloride, which is highly corrosive, causes corrosion problems of various wetted parts, and the amount of sludge is increased by 60-70%. Since it is strongly acidic, it is essential to use alkaline soda, which is an alkaline agent, in order to neutralize the treated water.

In addition, fine precipitates, such as ferric hydroxide produced in the neutralization process is bad colloidal sedimentation, and because it is not completely removed from the settling tank, sand filtering device, upflow filtration device, etc. other than the settling tank must be additionally installed.

The use of chemical agents such as inorganic coagulants and neutralizers is essential when the liquid corrosion method is used, and their proper dosage is controlled by PH. Due to the characteristics of the pH control system, the response speed is slow and the current time control is impossible. It is very troublesome to maintain, such as deterioration of the sensing part easily, requiring frequent correction and replacement.

When the maintenance of the proper pH control system is not performed, the pH control is not good, and therefore, the amount of inorganic coagulant is not added, so that the removal of soluble BOD by ferric chloride is not sufficient, resulting in difficulty in satisfying the quality of the discharged water.

In addition, from January 1, 1999, COD is added to the effluent standard items applied to the livestock wastewater treatment plant and manure treatment plant, so that high treatment facilities such as activated carbon adsorption units need to be provided.

In addition, the conventional organic wastewater purification method is because the entire process is made by batch operation (Batch) operation is not possible due to the natural discharge due to gravity, which is accompanied by the hassle and complexity of transferring to the pump each time the end of the process, As a result, a number of pumps are required, and a storage tank for temporarily storing the transferred liquid is required after every unit process, and thus a large number of tanks are required. Since each unit process is performed sequentially, the operation manager is always on site. There is a disadvantage to be present.

The present invention has been made in view of the above-mentioned problems of the conventional organic wastewater purification method, and in the pretreatment step, it is possible to remove colloidal particles and suspended soils, thereby reducing the BOD load in the subsequent biological treatment process. In the biotreatment stage, the high concentration of MLSS is maintained to increase the purification efficiency.In the solid-liquid separation process, the concentrated wastewater is concentrated by returning a portion of the concentrated sludge to keep the MLSS concentration of the bioreactor high. By dehydrating only the sludge, it significantly reduces the dewatering equipment and dehydration time of the sludge, and maintains the SS concentration of the treated water extremely low, and it treats the remaining BOD as well as COD by treating it with ozone with strong oxidation instead of the chemical coagulant of the existing iron salt system. , Discoloration, sterilization and complicated maintenance It eliminates the need for chemical treatment and consequent PH control, and does not require backwashing of the filtration device, which reduces the amount of waste water as much as backwashing water, and adopts the continuous treatment method, thereby reducing the number of tanks and transfer pumps, thus reducing the initial investment and Its purpose is to provide a method for the purification of organic wastewater which significantly reduces maintenance power costs and also eliminates the need for daily dehydration by storing concentrated sludge and dewatering as needed.

In order to achieve the above object of the present invention, the present invention provides an ultrafine bubble floatation apparatus having a bubble diameter of 5 to 50 microns at the rear end of the storage tank in the pretreatment stage and the rear end of the bioreactor in the biotreatment stage. In the post-treatment step, the ozone generating device is installed in addition to the microbubble flotation device, thereby purifying the organic wastewater.

In addition, the ultrafiltration membrane device (Ultra Filtration Membrane) is installed in place of the microbubble flotation device in the post-stage treatment step.

In addition, it is characterized in that the pipe and the pump to configure the continuous processing method by the inlet and conveyed the treated water of the micro-bubble flotation apparatus continuously in the subsequent process.

Due to these characteristics, wastewater to be treated by temporarily staying in the storage tank after homogeneous matter and sand are removed and homogeneous liquid is processed by the action of adhesion and flotation of the microbubbles to the floating particles by the microbubble flotation device installed in the pretreatment step. Colloidal, particulate, and suspended sediments are removed to reduce the BOD load in subsequent biotreatment processes. In the biotreatment process, another microbubble flotation device connected to it improves dehydration efficiency and high concentration MLSS concentration in the bioreactor. In the post-treatment, the ozone generator used in combination with another microbubble flotation device enables not only residual BOD, but also COD, discoloration, and sterilization. do.

As a result, the facility is greatly simplified and the maintenance cost is greatly reduced. In particular, the number of tanks and pumps is reduced because it is processed by the continuous treatment method, thereby significantly reducing the initial facility investment cost and the maintenance power cost.

In addition, in the case of applying the ultrafiltration membrane apparatus instead of the microbubble flotation apparatus in the post-stage treatment process applied to the above embodiment, the same effects as in the application of the microbubble flotation apparatus are obtained.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. 2 is a process diagram showing a preferred configuration of the present invention, Figure 3 is a conventional configuration of the microbubble floating apparatus to be applied to the present invention, Figure 4 is an ultrafiltration membrane device for applying to another embodiment of the present invention It is a typical cross-sectional block diagram.

First, an embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3. According to FIG. 3, the method for purifying organic wastewater according to the present invention includes a pretreatment step including a debris removal device 1, a desalination device 2, a storage tank 3, and a microbubble flotation device 4, and a bioreactor. (5) and a biological treatment step comprising a microbubble flotation device (6), a post-treatment step including an ozone contacting tank (8) equipped with an ozone generating device (7) and a microbubble flotation device (9), and a sludge Dewatering the sludge obtained from the microbubble flotation device (6) installed in the biological treatment stage, including the reservoir (10), flocculation tank (11), dehydrator (12) and the microbubble flotation device (9) installed in the post-treatment step. It consists of agglomeration and dehydration process. The application technology pursued by the present invention is in the microbubble flotation apparatus (4) (6) (9) installed in each step.

This microbubble flotation device is to achieve a conventional configuration as shown in Figure 3, it will be briefly described. That is, the microbubble flotation apparatus includes a floating tank 20, a pressure pump 21, a microbubble generating device 22 and the flotation sludge removal device (23).

In this configuration, the floating tank 20 is filled with sewage to be treated, and pressurized pump 21 is supplied with pressurized water to be sent to the microbubble generator 22, and in the microbubble generator 22, about 5-50 microns. A micro bubble is generated and flows into the bottom of the floating tank 20, and the introduced micro bubbles are floated in contact with the sewage liquid in the floating tank to float and float floating soils and colloidal floats contained in the sewage.

The injured sludges are collected by the injured sludge removal apparatus 23 installed at the top, and the sludge removed is a device that is transferred to the next process.

In other words, the microbubble flotation apparatus has a main function of removing colloidal particles and floating soils by using adhesion force and flotation force of the fine air to the floating particles.

The operation and effects for each process of the present invention in which such a microbubble flotation device is installed at each step will be described. As shown in FIG. 2, the organic wastewater introduced into the input tank is first removed from the sewage in the sewage by a debris removal device 1 consisting of a drum screen and a squeegee press and the like. It is precipitated and removed.

The sewage from which the contaminants and sand are removed is temporarily stored in the storage tank 3, and after being homogenized in the liquid phase, is transferred to the microbubble flotation apparatus 4. The sewage filled in the floating tank 20 of the microbubble flotation apparatus 4 is suspended in the liquid due to the flotation of the microbubbles generated from the pressure pump 21 and the microbubble generator 22 and the colloidal floatation. Injuries.

In other words, it removes about 15-20% of BOD by removing floating soils and colloidal suspended solids, as well as over 2mm of contaminants not removed in the pretreatment stage by the adhesion and flotation force of microbubbles. It is to reduce the load of suspended solids (SS) of the oxygen to improve the efficiency of oxygen dissolution, and to bring the effect of preventing effective capacity erosion.

In other words, the BOD load is reduced in the subsequent biotreatment process, resulting in the reduction of the capacity of the bioreactor, the treatment time, and the blower capacity.

As a result, the pretreatment step is completed, and the floating float generated at this time is transferred to the pressure dehydrator 13 together with the condensate collected from the debris removal device 1 to have a dehydration process.

Next, enter the bioprocessing stage. That is, the sewage removed by the fine bubble flotation device 4 of the pretreatment step to the fine suspended soils and colloidal floats flows into the following bioreactor 5, and the inflow does not depend on the pumping force and is connected to the connection pipe. It is introduced into the continuous treatment method that naturally falls.

Sewage flowing into the bioreactor 5 is supercorrosive. That is, organic sewage is oxidatively decomposed by active growth of aerobic bacteria group to form a suspension to purify organic sewage.

In this biotreatment process, keeping BOD-MLSS low and lengthening SRT (Sludge Retention Time solid retention time) increases the purification efficiency. Conventional concentration facilities to increase MLSS include belt type, gravity tank and centrifugal force. There was a Screw Decanter (DAF) Dissolved Air Flotation (DAF), but the gravity tank was limited to 1% concentration of concentrated sludge. In case of sludge poor sedimentation, the concentration is poor, and in the case of the screw decanter or the belt type, the facility cost and the maintenance cost were much higher than the efficiency, and in the case of the DAF, the bubble diameter is large, so that the concentration efficiency is low. The concentration of the concentrated sludge is 6% or more by connecting the microbubble flotation device (6) to the rear end of the bioreactor (5). In addition, high dissolved oxygen (DO) is maintained by the micro-bubble flotation apparatus to bring about the effect of re-aeration to bring additional BOD removal effect, improve the dehydration efficiency, maintain the high concentration of MLSS concentration in the bioreactor It is possible.

At this time, the concentration of the concentrated sludge is more than 6%.

On the other hand, by concentrating the biological wastewater is concentrated, a portion of the concentrated sludge is returned to maintain a high MLSS concentration of the bioreactor, and the remaining concentrated excess sludge is transferred to the sludge storage tank 10 to be dehydrated.

That is, the flocculation tank 11 is agglomerated with a polymer flocculant and dehydrated in the dehydrator 12 to obtain a dehydration cake and a stripping liquid. The dewatering cake is produced as a mature compost by the composting device to be used for agriculture, and the desorption liquid is returned to the storage tank (3) of the pretreatment stage to be combined with the new sewage to be treated.

As a result, the sludge dewatering facility is drastically reduced, and the SS concentration (suspended sludge) of the microbubble flotation apparatus is extremely low, and in some cases, it is possible to discharge the sludge as it is.

In the conventional liquid corrosion method, a significant amount of SS (300-500 ppm) was included in the desorption solution and the dehydrator washing water after dehydration, and in order to be suitable for the discharged water, SS had to be additionally removed by a sand filtration device and an upstream and downstream filtration device. .

In addition, 10-20% of Back Washing Water was required for each of these filters, resulting in an increase of 20-40% of wastewater to be treated.

However, in the present invention, since backwashing is not necessary, the amount of wastewater to be treated is reduced by that much, and the SS of the treated water can obtain water quality of 5 mg / l or less, which greatly simplifies the facility and significantly reduces maintenance costs.

Next, a post-processing step is performed.

The purified filthy water from the microbubble flotation device 6 in the biological treatment step is introduced into the ozone contacting tank 8 equipped with the ozone generator 7 to be ozone treated.

In other words, unlike conventional methods that used chemical coagulants based on iron salts, they are treated with ozone with a strong myth, so that BOD, COD, discoloration, and sterilization are compact, especially from 99.1.1. It can be discharged below the applicable COD regulation value, and the facilities such as various types of chemical supply pumps and chemical storage facilities are omitted, and complicated PH control is unnecessary.

Finally, the wastewater subjected to such ozone treatment finally passes through another microbubble flotation device 9, thereby completing the method for purifying organic wastewater according to the present invention.

At this time, the sludge generated in the microbubble flotation device 9 is returned to the sludge storage tank 10 installed in the coagulation treatment step and dewatered together with the sludge generated in the microbubble flotation device 6 in the previous chemical treatment step.

The present invention, which is purified at such a stage, is treated with a continuous treatment method unlike a batch treatment method in a conventional liquid corrosion method, and therefore, a treatment water storage tank and a pump for transporting each unit process are essential. Subsequently, a large number of tanks and a large number of pumps have an effect of solving the conventional problem that a lot of power costs are required among initial facility costs and maintenance costs. 4 shows an ultrafiltration membrane apparatus to be applied to another embodiment of the present invention. The ultra filtration membrane device (Ultra Filtration Membrane) is a device equipped with a tubular or flat membrane 31 having a filter function therein as a known technique.

That is, when the sewage is pumped through the inlet 32, the purified water passes through the outlet 33 formed on the side while passing through the plurality of internal unit membranes 31, and the concentrated water gradually concentrated at the rear end. It is conveyed to the next process through the outlet 34 formed.

The ultrafiltration membrane device 30 is provided in place of the microbubble flotation device 6, 9 having the configuration of the above-described embodiment. Accordingly, the ultrafiltration membrane device 30 is to replace the function of the microbubble floating device (6) (9) to obtain the effect that depends on the application of the microbubble floating device.

However, the ultrafiltration membrane device 30 must pass the sewage using a pressurized pump, and should be periodically cleaned or replaced. In this case, a backwash water and a backwash water generating device are required, and an increase in the amount of wastewater due to backwash water and There may be problems such as an increase in the cost of replacement.

As described above, the method for purifying organic wastewater according to the present invention applies each microbubble flotation device or ultrafiltration membrane device to reduce BOD load, prevent blockage of pipes, prevent wear of pumps, and dissolve oxygen in bioreactors. Increased efficiency, prevention of effective capacity encroachment of various crude volumes, maintenance of high concentrations of MLSS, the elimination of the use of chemical coagulants in the iron salt system, and the adoption of a continuous treatment method, greatly reducing facility and maintenance costs and maximizing purification efficiency. It is effective.

Claims (5)

The microbubble flotation device (4), including the debris removal device (1), the sanding device (2), the storage tank (3), and the microbubble flotation device (4), removes the floating projections and colloidal flotation materials. Pretreatment step; A biotreatment step including a bioreactor 5 and a microbubble flotation device 6 to maintain a high concentration of MLSS in the bioreactor by the microbubble floater 6; Strong oxidizing power in place of the chemical coagulant of the iron salt system by the ozone generating device 7 and the ozone contacting tank 8, including the ozone contacting tank 8 having the ozone generating device 7 and the microbubble flotation device 9 The treatment method of organic wastewater, characterized in that the treatment with ozone having the purified as a post-treatment step that will be COD, decolorization, sterilization as well as the remaining BOD. The physiochemistry of claim 1, wherein the biological treatment step includes a sludge storage tank (10), a flocculation tank (11), and a dehydrator (12) to dehydrate the sludge obtained from a later stage microbubble flotation device (6) (9). A method of purifying organic wastewater, characterized in that it further comprises a treatment step. The method for purifying organic wastewater according to claim 1, wherein the microbubble flotation apparatus (4) (6) (9) installed in each step generates ultra-fine bubbles having a bubble diameter of 5-50 microns. The process of claim 1, wherein the process of each step is such that the treated water of the pre-treatment microbubble flotation apparatus 4 can be introduced into the bioreactor 6 or returned to the storage tank 3 so as to enable continuous or batch treatment. A method for purifying organic wastewater, comprising constituting a pipe and a pump. The method of purifying organic wastewater according to claim 1, wherein the ultrafiltration membrane device (30) is purified instead of the microbubble flotation device (6) (9) applied in a later step.