KR20010028800A - Process for Biological Treatment of Waste Water with Zeolite Powder - Google Patents

Abstract

PURPOSE: Provided is a method for treating sewage and wastewater using powdered zeolite, which can remove high concentration nitrogen without additional installation of a zeolite ion-exchange or regeneration device and enhance settling property of sludge. CONSTITUTION: The sewage and wastewater treatment method is characterized in that, i) the reaction tank consists of an aerobic tank, an anoxic tank or an anaerobic tank, and a settling tank, in order; and ii) sewage and wastewater are flowed into the anoxic tank or the anaerobic tank, sent to the settling tank with powdered zeolite, and returned to the aerobic tank.

Description

Process for Biological Treatment of Waste Water with Zeolite Powder

The present invention relates to a method for treating sewage and wastewater using powdered zeolites in biological treatment tanks. More specifically, the present invention is a sewage that removes nitrogen and phosphorus as well as organic matter present in sewage and wastewater by continuously circulating using powdered zeolite in a biological treatment tank consisting of an aerobic, anaerobic, and sedimentation tanks. And a method for treating wastewater.

Most conventional sewage / wastewater treatment plants are using / operated sludge process, but this process is mainly for the removal of organic matter, and it is the process of nitrogen and phosphorus, which are known to cause eutrophication of appeal, which is a serious social problem recently. It is not suitable as a removal process. Therefore, efforts are being made in developed countries to replace these activated sludge methods. For example, A / O method, anaerobic tank, anaerobic tank and one aerobic tank, which have one anaerobic tank and one aerobic tank, Arranged methods such as the A ² / O method, the postrip method, the Bardenpho method, the VIP method, and the continuous batch method (SBR) are known. However, these processes have limited removal efficiency in wastewater treatment containing high concentrations of nitrogen or phosphorus, not only needing a large site for carrying out the process, but also difficulty in stable operation of the reactor.

In general, a method for biologically removing ammonia nitrogen present in sewage / wastewater is carried out by nitrifying bacteria such as nitrosomonas or nitrobacter under aerobic conditions. It is carried out by a nitriding-denitrification process in which the converted nitrate nitrogen is reduced to nitrogen gas by the action of denitrification bacteria under anaerobic or anoxic conditions. In order to facilitate this process, first, the ammonia nitrogen should be converted into the nitrate nitrogen form by nitrifying bacteria in the aerobic tank, and the denitrification process should be performed smoothly in the anaerobic tank or anoxic tank. However, in the case of high nitrogen containing wastewater having ammonia nitrogen concentration in the range of 500-2500 mg / l, such as leather wastewater, livestock wastewater, chemical wastewater, and raw leachate, the activity of nitrifying bacteria is inhibited by the high concentration ammonia, In addition, due to the insufficient amount of organic matter compared to the ammonia concentration, nitrification itself is not well made, there has been a difficulty in removing nitrogen.

On the other hand, as a method of removing biological phosphorus, a process using an excess intake of phosphorus to allow microorganisms to ingest in aerobic conditions more than that released by anaerobic conditions by a treatment process operated under an anaerobic-aerobic condition has been developed and put into practical use. In the case of the ammonia nitrogen-containing wastewater of high concentration, the removal of phosphorus is also difficult because excessive nitrate nitrogen prevents the release of phosphorus accumulated in the microorganism.

In an effort to solve this problem, researches for biological wastewater treatment of sewage / wastewater using the excellent selectivity of natural zeolite for ammonia are being actively conducted (see Korean Patent Publication No. 97-2624, 97-2628, 97-9650, 97-11327, 97-11330, Korean Patent Publication Nos. 99-15977 and 99-18076.

The method described in the above prior art document is generally provided with a zeolite filter reactor or a zeolite regeneration tank, etc., separately from the outside, raw water or treated water containing ammonia nitrogen, return water containing microorganisms of nitrification tank, zeolite Regeneration water or the like is introduced to reduce ammonia concentration by using a method such as ion exchange and removal of ammonia in advance, or by sending microorganisms of raw water and nitrification tank to a zeolite reaction tank to cause ion exchange and nitrification at the same time. However, in the case of such a method, as described above, an additional zeolite reactor is essentially required, which is uneconomical, and clogging may occur in the zeolite reactor.

In addition, when ion exchange of ammonia by zeolite is saturated, a chemical method of adding a substance such as sodium chloride for regeneration of the zeolite, or a biological regeneration method of treating the zeolite by returning microorganisms in the biological treatment tank is used. However, these chemical methods are simple, but they are expensive to recycle, and moreover, they pose a problem of environmental pollution due to the use of chemicals for regeneration, and biological regeneration methods, although economical, require the installation of additional facilities needed for regeneration. In addition, there is a problem in that wastewater containing nitric acid or nitrite nitrogen is generated.

Therefore, in order to solve the above problems, a simple change in the operation of the conventional activated sludge process and the addition of a certain amount of powdered zeolite without the additional installation of the auxiliary device related to the zeolite, as well as low concentration, especially high concentration nitrogen, such as leather, livestock, leachate, etc. New biological sewage / wastewater treatment methods have been proposed to increase the efficiency of wastewater treatment. That is, after a certain amount of powdered zeolite is introduced into a series of biological treatment tanks consisting of anaerobic or anaerobic tanks, aerobic tanks and sedimentation tanks, the powdered zeolites and sludges pass through the respective reaction tanks according to the flow of sewage and wastewater. An economical biological sewage / wastewater treatment method has been proposed in which organic matter is removed, denitrified and dephosphorized, and then the powdered zeolite is returned together with the sludge to be biologically regenerated in each reactor (see Korean Patent Application No. 98-8257).

However, in this case, although nitrification and precipitation were improved, they were not satisfactory in terms of nitrogen removal efficiency.

It is therefore an object of the present invention to provide a biological sewage / wastewater treatment method using a zeolite which does not require the installation of additional accessory equipment related to the zeolite as described above and which also has a high nitrogen removal efficiency.

The object of the present invention is the reaction tank consists of aeration tank, anaerobic tank or anaerobic tank and settling tank, it can be achieved by the sewage / wastewater treatment method of supplying zeolite powder and sewage / waste water to the anaerobic tank or anoxic tank.

In the sewage / wastewater treatment method of the present invention, the reaction tank is composed of an aeration tank, an anaerobic tank or an anaerobic tank, and a settling tank, and zeolite powder and sewage / wastewater raw water are supplied to the anaerobic tank or anoxic tank.

According to the method of the present invention, the powdered zeolite is administered in a certain amount according to the ammonia nitrogen concentration of the sewage / wastewater flowing into the anaerobic tank or the anaerobic bath, and the ammonia nitrogen of the sewage / wastewater is ion exchanged to these powder zeolites. The powdered zeolite ion-exchanged with ammonia nitrogen is transferred to the aerobic tank via the settling tank and converted into nitrous or nitrate nitrogen by the nitrifiers in the aerobic tank, and the converted nitrous or nitrate nitrogen is transferred to the anaerobic tank or anoxic tank. And denitrified by denitrification bacteria and discharged into nitrogen gas. In addition, the zeolite is regenerated by conversion to nitrous or nitrate nitrogen in the aerobic tank.

Therefore, according to the sewage / wastewater treatment method of the present invention, it is possible to economically increase the removal efficiency of nitrogen and phosphorus, especially nitrogen, as well as organic matter in the sewage / wastewater through ion exchange and biological regeneration mechanisms of zeolites. Precipitation can be improved and the effect of zeolite can be utilized to the maximum.

In general, conventional biological treatment reactors are configured in the order of anaerobic tanks or anaerobic tanks, aerobic tanks, and settling tanks according to their functions and functions, or by using the same single reactor to form the above-described anaerobic, anaerobic, aerobic, etc. states. Was driven.

However, in contrast, the reaction tank according to the present invention is configured in the order of aerobic tank, anaerobic tank or anoxic tank, and precipitation tank. Up to now, in the biological treatment method of sewage / wastewater, when the reaction tank is operated in the order of aerobic and anaerobic tanks or anaerobic tanks, it is difficult to achieve a smooth solid-liquid separation due to sedimentation by nitrogen gas generated by the denitrification process in the anoxic tank. In addition, the ammonia nitrogen removal efficiency was inevitably dependent on the return ratio.

However, in the method of the present invention, when a certain amount of powdered zeolite is added to the reaction tank, in the anaerobic or anoxic tank, which is a biological reaction tank, and the aerobic tank, the powdered zeolite and microorganisms form a stable floc, thereby improving precipitation. In this case, the ammonia nitrogen introduced into the anoxic tank is ion exchanged to the zeolite, solid-liquid separated from the settling tank, and returned to the aerobic tank. The ammonia nitrogen ion-exchanged to the returned zeolite is converted to nitrate nitrogen by the nitrification mechanism, whereby the zeolite regeneration is performed. On the other hand, nitrogen converted to nitrous or nitrate nitrogen from zeolite is introduced into an anoxic tank, reduced to nitrogen gas by denitrification bacteria, and completely removed to the atmospheric phase. At this time, organic matter contained in sewage / wastewater is denitrified by denitrification bacteria. It is used as a carbon source in the process and removed. In addition, heavy metals are adsorbed to the zeolite or by the microorganisms, phosphorus is removed by the microorganisms.

Thus, by using the method according to the present invention as described above, it is possible to economically and effectively remove nitrogen, phosphorus, heavy metals and organic substances, etc. present in the sewage / waste water.

In the above method of the present invention, the return ratio from the settling tank to the aerobic tank greatly affects the efficiency of the method. In general, when the return ratio is less than 0.5, sludge and zeolite may be kept in the settling tank for a long time to inhibit sludge decay and smooth regeneration of the zeolite, and when 5 or more, too much oxygen may be supplied to the anoxic tank to inhibit denitrification. Therefore, the conveyance ratio is preferably in the range of 0.5 to 5.

According to the invention, the sewage / wastewater to be treated is first introduced into an anaerobic or anaerobic tank. The ammonia nitrogen of the sewage / wastewater introduced into the anaerobic or anaerobic tank is ion exchanged to the zeolite, solid-liquid separated from the sedimentation tank, and the sludge separated is returned to the aerobic tank and the supernatant is discharged to the treated water. The ammonia nitrogen ion-exchanged in the returned zeolite is converted into nitrite or nitrate nitrogen by chemical and biological mechanisms by nitrifying microorganisms in an aerobic tank and is released in the liquid phase from the zeolite, thereby achieving continuous regeneration of the zeolite. On the other hand, the nitrous or nitrate nitrogen released into the liquid phase is moved to an anoxic tank or anaerobic tank and reduced to nitrogen gas by the denitrification microorganism to be removed and released to the atmosphere. It is used as a carbon source in the denitrification process of the anaerobic tank and is removed. The zeolite regenerated in the aerobic tank may be ion exchanged again with the ammonia nitrogen of the sewage / wastewater flowing into the anaerobic or anaerobic tank.

Therefore, in the method of the present invention, by performing the chemical-biological continuous mechanism as described above, there is no need to install additional facilities for regenerating the zeolite, and since the zeolite regeneration is possible in the aerobic tank as a single process, the zeolite administered to the reactor is artificially There is no need to play. That is, in the case of a process using a zeolite, a separate chemical method or a biological regeneration method should be used to regenerate the zeolite used, but in the method according to the present invention, a microorganism such as a biological mechanism occurring in a reaction tank, that is, nitrification and denitrification, etc. Since the zeolite is continuously regenerated by the mechanism, there is no need for additional facilities, and since the zeolite provides a stable place necessary for the growth of microorganisms on its surface, a stable floc is formed around the zeolite, thereby improving precipitation. Stable and economical treatment of sewage / wastewater.

Powdered zeolites that can be used in the process of the invention can be used in any form with cation exchange capacity, preferably represented by MO.Al _x O _y .mSiO ₂ .nH ₂ O (M is alkaline earth metal) It is a natural zeolite based on hydrous aluminum.

The powdered zeolite to be used preferably has a particle size of 10 to 100 μm. In general, when the particle size is less than 10 μm, the zeolite particles are not likely to remain in the reactor in the wastewater treatment process and are more likely to flow out. If the particle size is larger than 100 μm, free flow in the reactor may be difficult and may cause clogging or damage of the pump.

In the sewage / wastewater treatment method according to the present invention, the configuration of the biological reaction tank was described in order of aerobic tank, anoxic tank, or anaerobic tank and settling tank for convenience, but this is to more clearly explain the present invention, and each biological reactor was treated. Depending on the characteristics of the sewage / wastewater to be desired and the conditions of the individual treatment plant, it may be variously configured. In other words, the biological reaction tank according to the present invention generally consists of an aerobic tank, an anaerobic tank or an anaerobic tank and a precipitation tank, but when it is necessary to remove high concentrations of nitrogen and phosphorus, the aerobic tank, anaerobic tank or anoxic tank may be repeated. In addition, each reactor may be composed of a membrane in one single reactor, or may be separately divided into each reactor. That is, the change of the operation sequence or method of a continuous batch reactor or a single reactor is also included in this invention.

On the other hand, the amount of sludge to be disposed in the form of waste sludge is disposed so that the sludge residence time of the entire reaction tank is kept constant, and in consideration of the amount necessary for the efficiency of the entire reactor or the amount of powder zeolite included in the waste sludge, In addition, powdery zeolite can be supplied to the reactor.

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

<Example>

According to the method of the present invention, a total of 8 liters of reaction tanks consisting of 2 liters of anoxic tank and 6 liters of aeration tank was used, and the reaction ratio was operated at 3Q. Sewage / wastewater samples include leather wastewater (total nitrogen: 300-500 mg / l) and domestic chemical wastewater from N chemical plants that enter the J leather treatment plant containing high concentrations of ammonia nitrogen. Total nitrogen: 800-1,000 mg / l), for about 2 months. Methanol was used as an external carbon source due to the lack of organic materials for denitrification.

As a result, high total nitrogen removal efficiency of more than 90 was obtained, and the sedimentation of sludge was improved visually. In addition, organic matter, total phosphorus and suspended solids were also stably removed, and it was confirmed that zeolites were biologically stable and continuously recycled without additional administration of zeolites. The experimental results are summarized in Table 1 below.

division Ammonia Nitrogen (NH ₄ ⁺ -N) Total Nitrogen (T-N) Chemical oxygen demand (CODcr) Total Person (T-P) Suspended solids (SS) Settleability (SVI) Leather wastewater Influent (mg / L) 340 360 620 * 10 140 10 Effluent (mg / L) 28 35 180 3 40 Removal rate () 92 90 71 70 71 Chemical wastewater Influent (mg / L) 360 1,000 270 * 10 One 26 Effluent (mg / L) 40 70 70 6 30 Removal rate () 89 93 74 40 - *: The value excludes external carbon sources.

In order to increase the efficiency of organic matter removal, additional aerobic or physicochemical treatment tanks can be operated in parallel with this process. In this case, high nitrogen removal efficiency and organic matter removal efficiency can be obtained.

According to the present invention, there is no need to install additional accessory equipment related to the zeolite, and a biological sewage / wastewater treatment method using a zeolite having a high nitrogen removal efficiency is provided.

Claims (6)

The reactor consists of an aerobic tank, an anaerobic tank or anaerobic tank, and a settling tank, and powdered zeolite is added to the anaerobic tank or anaerobic tank, and the sewage / wastewater is transferred to the settling tank along with the powdered zeolite introduced by adding to the anoxic tank or anaerobic tank. , Biological wastewater treatment method characterized in that returned to the aerobic tank. A method of treating biological wastewater, characterized by introducing powdered zeolite and sewage / wastewater in an anaerobic or anaerobic state in a continuous batch biological reactor in which aerobic, anaerobic or anaerobic conditions and precipitation conditions are repeated. 3. The powdery zeolite according to claim 1 or 2, wherein the powdered zeolite is a natural zeolite having a hydrous aluminum as a main component represented by MO.Al _x O _y .mSiO ₂ .nH ₂ O (M is an alkaline earth metal). How to. The method of claim 1 wherein the diameter of the powdered zeolite is 10 μm-100 μm. 3. The method according to claim 1 or 2, wherein the powdered zeolite is administered in a range of 0.5 to 5 times the appropriate amount according to the ion exchange capacity of the zeolite to the ammonia nitrogen of the charged / waste water. The method of claim 1 or 2, further comprising supplementing zeolite loss due to sludge disposal.