KR19990074576A - Biological treatment of wastewater by continuous circulation / regeneration in biological treatment tank of powdered zeolite - Google Patents

Abstract

After a certain amount of powdered zeolite was introduced into a series of biological treatment tanks consisting of anaerobic or anaerobic tanks, aerobic tanks, and settling tanks, the powdered zeolites and sludges passed through respective reactors according to the flow of sewage and wastewater. COD reduction, heavy metal adsorption, denitrification, dephosphorization, and then the powdered zeolite is returned to the sludge and economical biological sewage and wastewater treatment method which is naturally regenerated in each reactor. A very economical and effective method of treating sewage and wastewater is provided that can effectively treat sewage and wastewater without the installation and introduction of additional biological treatment devices.

Description

Biological treatment of wastewater by continuous circulation / regeneration in biological treatment tank of powdered zeolite

The present invention relates to sewage and wastewater treatment methods for removing organic matter, heavy metals, odors, nitrogen and phosphorus present in sewage and wastewater using powdered zeolites in biological treatment tanks. More specifically, the present invention is to administer a certain amount of powdered zeolite to the biological treatment tank consisting of anaerobic or anoxic tank, aerobic tank and sedimentation tank to continuously circulate, so that organic matter, heavy metals, odor, nitrogen and phosphorus contained in sewage and waste water It relates to a sewage and wastewater treatment method for removing the.

Conventionally, most of the sewage and wastewater treatment plants are applied with activated sludge process, but this process is mainly the process of removing organic matter, and it is known as a substance causing odor removal, heavy metal removal, and eutrophication of appeal, which is a serious social problem recently. It is not suitable for the nitrogen and phosphorus removal process. Therefore, efforts are being made in developed countries to replace the activated sludge process, for example, one anaerobic tank and one aerobic tank, two anaerobic tanks, and one anaerobic tank. The A ² / O method, the postrip method, the Bardenpho method, the continuous batch method (SBR) and the like are known. However, these processes do not have high removal efficiency in treating wastewater containing high concentrations of nitrogen or phosphorus, they require not only a large site for performing the process, but also have difficulty in stably operating the reactor. have.

In general, in order to remove nitrogen biologically, ammonia nitrogen present in sewage and wastewater is removed by nitrifying bacteria (for example, nitrosomonas or nitrobacter) under aerobic conditions. The nitrate nitrogen thus converted is reduced to nitrogen molecules by the action of denitrification bacteria under anaerobic or anaerobic conditions. In order for this process to proceed smoothly, first, the conversion from ammonia to nitrate nitrogen form by nitrifying bacteria in the aeration tank should be well performed, and then denitrification should be performed smoothly in the anaerobic or anoxic tank. However, despite the fact that nitrogen and phosphorus affecting eutrophication of the lake should be almost completely treated in the treatment plant, leather wastewater, which is a wastewater containing a high concentration of nitrogen having ammonia nitrogen concentrations in the range of 500-2500 mg / l, In the case of livestock wastewater and leachate, the existing activated sludge process does not perform nitrification itself due to the inhibitory action of nitrifying bacteria due to the high concentration of ammonia and the amount of organic matter that is insufficient compared to the ammonia concentration. As it is difficult to remove efficiently, it is increasing the environmental pollution of the ecosystem.

On the other hand, the biological phosphorus removal method using a conventional anaerobic-aerobic treatment process to operate, the process for allowing the intake of phosphorus in anaerobic conditions more than the microorganisms released in aerobic conditions has been developed and practical, the high concentration In the case of wastewater containing ammonia nitrogen, the removal of phosphorus is also difficult because excessive nitrate nitrogen interferes with the release of phosphorus accumulated in the microorganism.

On the other hand, research results for biological treatment of sewage and wastewater by applying the excellent selectivity of ammonia of natural zeolites (e.g. Korean Patent Publication Nos. 97-2624, 97-2628, 97-9650, 97-11327, 97-11330, Korean Patent Application No. 97-44909, 97-44910). However, in these methods, a zeolite filter reactor or a zeolite regeneration tank or the like is separately provided to the outside, and raw water or treated water containing ammonia nitrogen, return water containing microorganisms in the nitrification tank, zeolite regeneration water, and the like are introduced therein. It is used to reduce the ammonia concentration by using a series of methods such as adsorbing and removing in advance from the zeolite reaction tank or sending microorganisms of raw water and nitrification tank to the zeolite reaction tank to cause adsorption and nitrification. In addition, when the adsorption of ammonia by the zeolite is saturated, a method of using a substance such as sodium chloride for regeneration of the zeolite or returning the microorganisms in the biological treatment tank to promote the regeneration is also described.

However, when the above-described method is used, there is a disadvantage in that an additional zeolite reaction tank is required, a cost burden due to artificial regeneration of the ammonia-adsorbed zeolite, and a clogging phenomenon in the zeolite reaction tank occurs.

The sewage and wastewater treatment method according to the present invention is to add a powdered zeolite in each treatment tank to adsorb and remove heavy metals, and to reduce organic matter by the microorganisms attached to the powdered zeolite and acting. In addition, this process promotes denitrification in an anaerobic or anoxic tank and nitrification in an aerobic tank to remove nitrogen and phosphorus by microorganisms, which can economically increase the removal efficiency of organic matter, heavy metals, odors, nitrogen and phosphorus in sewage and wastewater. A method is provided.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and in the existing activated sludge process, which occupies most of the wastewater treatment process, a simple change in operation and a certain amount of powdered zeolite without additional installation of an auxiliary device are required. By inputting, it is to provide a new wastewater and wastewater biological treatment process which can improve the treatment efficiency not only of wastewater containing low nitrogen but also wastewater containing high concentration of nitrogen such as leather, livestock, and leachate.

1 is a flow chart illustrating a biological treatment method for treating sewage and wastewater by continuously circulating / regenerating powdered zeolite in a biological treatment tank according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1, 2: primary sedimentation tank or physicochemical treatment tank

3: biological reactor

3-1: First anaerobic tank or anaerobic tank

3-2: First Unit

3-3: Second anaerobic tank or anaerobic tank

3-4: Second Unit

4, 5: secondary sedimentation tank

1A, 2A: inflow line of sewage and wastewater

3-2B: Partial Wastewater and Sludge Return Line in Primary Refuse Tank

3-2C, 3-4C: Treated Water Line

4B, 5B: sludge conveying line

4D, 5D: Sludge Spill Line

3-1E, 3-3E: Organics Supply Line

An object of the present invention is to solve the disadvantages of the conventional method, while a certain amount of powdered zeolite is introduced into a series of biological treatment tanks consisting of an anaerobic or anoxic tank, an aerobic tank, and a settling tank, and then, according to the flow of sewage and wastewater, The zeolite and the sludge pass through each reactor to perform biological COD reduction, heavy metal adsorption, denitrification, dephosphorization, and then the powdered zeolite is returned with the sludge to be naturally regenerated in each reactor. By sewage and wastewater treatment methods.

In the present invention, the reaction tank used in the sewage and wastewater treatment process is composed of a primary sedimentation tank, an anaerobic tank or an anaerobic tank, an aerobic tank, and a secondary sedimentation tank, and in the case of a process for treating sewage and wastewater containing nitrogen and phosphorus in high concentration, Or it may further include a continuous anaerobic tank or anaerobic tank, an aerobic tank if necessary after the anaerobic tank, aerobic tank. At this time, each reactor may be composed of a membrane in one reactor, or may be configured separately to each reactor. The flow of sewage and wastewater in the reaction tank may be introduced into an anaerobic tank or an anaerobic tank → an aerobic tank, or, if necessary, the treated water flowing out of the aerobic tank may be continuously introduced into a continuous anaerobic tank or an anaerobic tank → an aerobic tank.

Powdered zeolites that can be used in the present invention _{MO · Al x O y · mSiO} 2 · nH 2 O ( wherein, M is alkaline earth metal) can be selected from natural zeolite as a main component represented by the function of aluminum. The powdered zeolite usually has a diameter in the range of 25-1000 μm, but in order to maximize the treatment efficiency, it is preferable to use the powdered zeolite in the range 25-200 μm.

The wastewater treatment method of the present invention will be described in more detail below with reference to the drawings.

First, raw water of sewage and wastewater is introduced into the primary settling tank 1, and the coarse particles are precipitated by allowing a predetermined time to stay or coagulating the coarse particles through a physicochemical treatment method. Then, the anaerobic tank or anoxic tank (3-1), each of which is a biological reaction tank in which a predetermined amount of powdered zeolite is introduced into the upper raw water discharged from the sedimentation tank 1 through inflow lines 1A and 2A of sewage and wastewater raw water. And the reactor 3 composed of an aerobic tank 3-2. In an anaerobic or anoxic tank (3-1), ammonia nitrogen, heavy metals, and the like are adsorbed to the powdered zeolite, and powdered by nitrifying bacteria or freely floating nitrifying bacteria attached to the powdered zeolite in the aerobic tank (3-2). Ammonia adsorbed on zeolite and ammonia contained in wastewater in an aerobic tank are converted into nitrate nitrogen or nitrite nitrogen (nitriding process). Part of the wastewater in the powdered zeolite and the aerobic tank containing the converted nitrate nitrogen or nitrite nitrogen is returned to the anaerobic tank or anoxic tank (3-1) via the transfer line (3-2B) and adhered to the powdered zeolite. Denitrification bacteria or freely floating denitrification bacteria are attached to the powdered zeolite or nitrogen nitrite or nitrite nitrogen present in the return water is reduced to nitrogen molecules (denitrification process) to release nitrogen into the atmosphere. . The powdered zeolite from which the nitrogen molecules were removed in the anaerobic tank or anoxic tank (3-1) is present in the new sewage and wastewater source water introduced into the anaerobic tank or anoxic tank (3-1) through the sewage and wastewater inflow lines (1A, 2A). Adsorption of ammonia nitrogen again causes the nitrogen removal process to be repeated continuously. In the process, the remaining treated water except the returned water from the aerobic tank (3-2) is sent to the secondary settling tank (4) through the treated water line (3-4C), where the solid-liquid separation is used to treat biological wastewater. Will be made.

On the other hand, in the case of wastewater containing high concentrations of nitrogen such as leather wastewater, livestock wastewater, and leachate, the treated water coming out of the aerobic tank (3-2) has a high concentration of nitrate nitrogen or nitrite nitrogen. When directly exported to), the concentration of ammonia nitrogen is low, but the concentration of total nitrogen is high. Therefore, in order to remove nitrogen present in the sewage and wastewater, wastewater from the aerobic tank (3-2) is sent back to the secondary anaerobic tank or anoxic tank (3-3) via the treated water line (3-2C), and the primary The nitrogen removal process in the anaerobic or anaerobic and aerobic tanks can be repeated. That is, secondary denitrification occurs by denitrification bacteria attached to the powdered zeolite introduced with the wastewater from the reaction tank (3-2) and denitrifying bacteria floating freely in the secondary anaerobic tank or anoxic tank (3-3). This wastewater is sent back to the secondary aerobic tank (3-4), and the residual ammonia adsorbed to the powdered zeolite or the wastewater in the aerobic tank is adsorbed by the nitrifying bacteria which are attached to the powdered zeolite and grow freely under aerobic conditions. The residual ammonia contained is converted to nitrate nitrogen or nitrite nitrogen (nitrification process), attached to the powdered zeolite by denitrification bacteria or freely floating denitrification bacteria attached to the powdered zeolite, and present in the return water. Nitrate and nitrite nitrogen are reduced (denitrification process) to release nitrogen molecules into the atmosphere. By removing by, after the can so that when the inlet to the treatment water treated water line secondary settling tank (4, 5) via the (3-4C), facilitate the sludge and treated water of the solid-liquid separation is achieved.

Some of the sludge precipitated by solid-liquid separation in the secondary settling tank is sent back to the first anaerobic tank or anoxic tank (3-1) or, if necessary, to the second anaerobic tank or anoxic tank (3-3) through the sludge return line (4B, 5B). , And serves to supply the powdered zeolite back to the reactor.

In addition, some of the sludge precipitated in the secondary settling tank (4, 5) can be discharged to a certain amount through the sludge outflow lines (4D, 5D) to be used as a fertilizer containing zeolite. At this time, the amount of zeolite contained in the discharged waste sludge or an amount of powder zeolite additionally required in the reactor is supplied to the reactor 3 from the outside. In addition, in the case of wastewater containing high concentrations of nitrogen such as leather wastewater and leachate, the content of organic matter is absolutely insufficient compared to nitrogen, so the first anaerobic tank or anoxic tank (3-1), the second anaerobic tank or anoxic tank (3-3) Denitrification and dephosphorization activity of denitrifying bacteria and dephosphorus bacteria in anaerobic or anaerobic tanks (3-1, 3-3) by supplying organic substances through organic supply lines (3-1E, 3-3E) as much as the amount of organic matter that is insufficient compared to nitrogen content. To maximize the denitrification and dephosphorization efficiency can be improved. This process can also increase the removal efficiency if the removal efficiency is insufficient even in the above-described method by installing the third anaerobic tank, anoxic tank, and the third aerobic tank continuously after the second aerobic tank if necessary.

In addition, the removal of phosphorus is performed by removing the heavy metal adsorbed to the zeolite in the aerobic tanks (3-2, 3-4) and the microorganisms ingesting excess phosphorus from the settling tanks (4, 5) through the outflow line (4D). Can be removed at the same time.

In the process according to the invention, when the treated water from the first or second aerobic tank is returned to the first anaerobic tank or anaerobic tank or the second anaerobic tank or anaerobic tank, the return amount is within the range of 0.5-5 times the raw water inflow. Can be done in In addition, when a part of the sludge precipitated in the settling tank is returned to the anaerobic tank or anoxic tank, the conveyed amount is made within the range of 0.25-2 times the amount of raw water inflow and discharged in the form of waste sludge from the settling tank (4, 5). The amount of sludge is set so that the sludge residence time of the entire reaction tank is in the range of 5-50 days, and the amount of powder zeolite contained in the discharged sludge or the amount of powder zeolite necessary for the efficiency of the entire reactor is externally reacted with the reactor or the precipitation tank. Supply to

The present invention is described in more detail as follows.

The most characteristic aspect of the present invention is the anaerobic tank or anaerobic tank (3-1) → aerobic tank (3-2) → sedimentation tank (4), or 1 It is sent to the reaction tank which consists of secondary anaerobic tank or anoxic tank (3-1) → primary aerobic tank (3-2) → secondary anaerobic tank or anoxic tank (3-3) → secondary aerobic tank (3-4) → sedimentation tank (5), A predetermined amount of powdered zeolite is added to each of the reaction tanks so that ammonia nitrogen, heavy metals, and the like are adsorbed by the powdered zeolite in the anaerobic or oxygen-free tanks (3-1, 3-3), and then the aerobic tanks (3-2, 3-). 4) ammonia which is adsorbed to the powdered zeolite by the nitrifying bacteria growing on the powdered zeolite or freely floating nitrifying bacteria or the ammonia contained in the wastewater in the aerobic tanks (3-2, 3-4) I convert it to nitrous acid nitrogen . Part of the wastewater and sludge in the powdered zeolites and the aerobic tanks (3-2, 3-4) containing the converted nitrate nitrogen or nitrite nitrogen through the return line to the anaerobic tank or anoxic tank (3-1) (3-2B , 4B, 5B), and the nitrate nitrogen or nitrite nitrogen attached to the powder zeolite by the denitrifying bacteria or freely floating denitrification bacteria attached to the powdered zeolite or floating freely and reduced in the return water to nitrogen molecules. Can be released to the atmosphere. On the other hand, the powdered zeolite from which nitrogen molecules have been removed from the anaerobic tank or anoxic tank (3-1) is denitrogenated by re-adsorption of ammonia nitrogen present in the raw water (1A, 2A) introduced into the anaerobic tank or anoxic tank (3-1). The process may be repeated continuously, and this process may also be carried out in the aerobic tanks (3-2, 3-4) by the sludge outflow line ( By removing through 4D, 5D), heavy metal removal and dephosphorization can be performed simultaneously.

Furthermore, in the case where the content of organic matter is absolutely insufficient compared to nitrogen as in the case of wastewater containing high concentrations of nitrogen such as leather wastewater and leachate, the organic matter lacking the nitrogen content in the anaerobic tank or the anoxic tank (3-1, 3-3) is insufficient. Denitrification bacteria in anaerobic or anoxic tanks (3-1, 3-3) by separately supplying organic matter through the organic inflow lines (3-1E, 3-3E) by the amount or as necessary to reduce the chemical oxygen demand (COD). And to maximize the denitrification, dephosphorization activity of the dephosphorus bacteria, it is possible to improve the COD reduction, denitrification, dephosphorization efficiency by the microorganism. In addition, the process according to the invention conveys a portion of the treated water from the primary aeration tank (3-2) and the settling tanks (4, 5) and the settled sludge to the anaerobic or anoxic tank (3-1, 3-3). 3-2B, 4B and 5B), and discharge some of the sludge settled through the sludge outflow lines 4D and 5D in the settling tanks 4 and 5, and as much as the amount of powdered zeolite contained in the discharged sludge. Or supplying powdered zeolite from the outside to the reactor 3 in an amount necessary for increasing processing efficiency.

Hereinafter, preferred embodiments of the present invention are described. However, the following examples are only preferred examples of the present invention to aid the understanding of the present invention, and the present invention is not limited to the following examples.

<Example>

Leather wastewater (total nitrogen content of raw water; 500-600 mg / l) and leachate from K landfill (total nitrogen content of raw water: 1800-2200) containing high concentrations of ammonia nitrogen mg / l) of the raw water was subjected to the nitrogen removal test.

On the other hand, in this experiment, since the raw water contains a high concentration of nitrogen, the constitution of the reaction tank (3) is the anaerobic tank or anaerobic tank (3-1), the second anaerobic tank or anoxic tank (3-3) after the aerobic tank (3-2), Secondary aerobic tanks (3-4) were used, and each reactor was configured to be individually separated. The flow of sewage and wastewater in the reactor (3) is anaerobic or anoxic (3-1), aerobic (3-2), secondary anaerobic or anoxic (3-3), secondary aerobic (3-4), secondary It proceeded in order of aerobic tank (3-4).

As shown in FIG. 1, pilot plants having a scale of 9 tons and 1 ton were respectively manufactured, and the wastewater was introduced at an inflow rate of 3 tons and 0.3 tons per day, respectively, and then operated and tested by the method described above. 80-200 micrometers were used. As a result, a total nitrogen removal effect of 80-95% was obtained.

According to the present invention, by using the existing activated sludge process as it is, by changing only a slight operation mode, and by introducing only economical powder zeolite and, if necessary, cheap organic matter into the process, such as leather wastewater, livestock wastewater and leachate A method is provided for efficiently removing nitrogen and phosphorus from wastewater containing high concentrations of nitrogen.

Claims (7)

Anaerobic or anaerobic tanks, aerobic and sedimentation tanks, or, if necessary, anaerobic or anaerobic tanks, and subsequent secondary anaerobic tanks of raw water of sewage and waste water, or raw and sewage raw water that have undergone primary physicochemical treatment. Alternatively, a predetermined amount of powdered zeolite is introduced into a reaction tank including an oxygen-free tank and a secondary aerobic tank, and ammonia nitrogen and heavy metals are adsorbed by the powder-type zeolite in an anaerobic tank or an oxygen-free tank, and ammonia is absorbed by nitrifying bacteria in the aerobic tank. Some of the wastewater in the powdered zeolites and aerobic tanks containing the converted nitrate or nitrite nitrogen are returned to the anaerobic or anoxic tank and denitrified by nitrate or nitrite Nitrogen is removed by reducing it with nitrogen molecules, and nitrogen molecules are removed. The powdered zeolite is re-adsorbed ammonia nitrogen present in the return water flowing through the raw water or the aerobic tank introduced into the anaerobic tank or the anoxic tank, and the nitrogen removal process is repeated continuously. A biological wastewater treatment method comprising removing heavy metals and phosphorus by removing phosphorus-ingested microorganisms from the settling tank. The method of claim 1, wherein said powdered zeolite is _{MO · Al x O y · mSiO} 2 · nH 2 O ( wherein, M is alkaline earth metal) natural zeolites mainly of hydrous aluminum represented by the following. The method of claim 2 wherein the size of the powdered zeolite is in the range of 25 to 1000 μm in diameter, preferably 25 to 200 μm. The microorganisms according to any one of claims 1 to 3, wherein the powdered zeolite continuously performs denitrification and nitrification while moving in each reaction tank in parallel with the flow of waste water, thereby eliminating the need for a separate regeneration water. The method is characterized in that the continuous playback by the action of. The method according to claim 1, wherein when the treated water from the aerobic tank is returned to an anaerobic tank or an anaerobic tank, the conveyed amount is within a range of 0.5-5 times the amount of raw water inflow. The method of claim 1, further comprising conveying some of the sludge precipitated in the settling tank to an anaerobic tank or anoxic tank, wherein the returned amount is in the range of 0.25-2 times the raw water inflow. The method of claim 1, wherein the organic matter is supplied to the anaerobic tank or anoxic tank in an amount less than the nitrogen content or in an amount necessary to reduce the chemical oxygen demand (COD) when the organic content is insufficient in comparison with the nitrogen content. .