JP2992692B2 - Sewage purification method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of a method and an apparatus for purifying sewage, and more particularly, eutrophication contained in domestic sewage or sewage which accounts for a large part of water quality environmental pollution. Component and BOD as causative substances
TECHNICAL FIELD The present invention relates to techniques such as a method for purifying domestic sewage and sewage, which is capable of efficiently and economically removing organic substances as substances using physicochemical and biological methods.

[0002]

2. Description of the Related Art Conventionally, generally used methods for removing nitrogen from sewage include an ammonia stripping method, a chlorine injection method, an ion exchange method, and a biological denitrification method.

[0003] Ammonia Stri
The pping) method is a method in which an alkaline agent such as lime is added to domestic sewage or sewage, air is sucked through a contact tower while maintaining a pH of 10 or more, and ammonia is scattered as a gas, and nitrogen is easily removed. Although it is possible, the ammonia gas volatilization efficiency decreases at low temperatures, and the volatilized ammonia gas causes a problem of secondary pollution when scattered to the atmosphere, and the calcium carbonate generated causes scale to adhere to the contact tower nozzle and the like. There are problems such as doing.

The chlorine injection method is a method of injecting chlorine gas as an oxidizing agent into domestic sewage or sewage to oxidize NH ₄ ⁺ to N ₂ to remove nitrogen in sewage. By adjusting to the range, it becomes N ₂ , and if it is injected so that the ratio of Cl ₂ to NH ₄ ⁺ becomes appropriate, there is an advantage that the treatment of excess chlorine gas is not required, but when the pH cannot be controlled properly. Toxic trichloroamine (Trichl
oroamine) or THM (Trihal
However, biological denitrification methods are generally used to remove nitrogen from sewage because of problems such as generation of omethane).

In this biological denitrification method, nitrogen compounds are oxidized by nitrogen oxidizing bacteria and then reduced to N ₂ gas by denitrifying bacteria to remove nitrogen in sewage. It is applicable to nitrogen compounds and has the advantage of being removed as harmless nitrogen gas.However, the nitrogen removal rate is slow, and the activity of microorganisms at the time of temperature decrease is reduced, so the nitrogen removal efficiency is deteriorated and the liquid temperature is reduced. If the temperature is lower than 15 ° C., there is a problem that it is difficult to remove nitrogen.

The ion exchange method uses the selective ion exchange capacity of zeolite to adsorb and remove ammonia nitrogen contained in domestic sewage or sewage, and this adsorbed zeolite is neutral. This is a method of regenerating using a salt or an aqueous alkali solution or the like, and further treating ammoniacal nitrogen concentrated in the regenerating solution by an ammonia stripping method, an electrolytic method, or the like.

[0007] When adsorbing ammonia nitrogen in sewage, nitrogen can be removed even at low temperatures, the removal rate is fast, and the load is fluctuated. It is necessary to further treat the recycled waste liquid, and depending on the method, there is a problem of causing secondary contamination.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problems of the prior art, and is intended to reduce the nitrogen and BOD substances contained in sewage and the like even when the liquid temperature in winter falls. Physicochemical and biological sewage that can be removed, the exchanger that adsorbs nitrogen or organic substances is automatically regenerated without using a separate regenerating solution, and operation management is simple and management costs are low. And a method for purifying sewage and the like and an apparatus therefor.

[0009]

According to a first aspect of the present invention, there is provided a method of purifying sewage according to the present invention, wherein B is contained in sewage by passing through a contact tank.
The first step is to remove the organic matter as the OD substance into the activated sludge and to remove the ammonia nitrogen into the zeolite, and to sediment and separate the activated sludge and the zeolite into which the organic matter and the ammonia nitrogen in the sewage passed through the contact tank are respectively adsorbed. The second step in which the supernatant liquid from which the pollutant components have been removed is discharged, and the activated sludge and zeolite separated and settled are transferred to the oxygen-free part of the regeneration stabilization tank partitioned into an oxygen-free part and an aerobic part. Mixed with the internal circulating fluid containing oxidized nitrogen circulated from the aerobic part, and the oxidized nitrogen in the circulated fluid is reduced to nitrogen gas by the action of denitrifying bacteria using organic substances adsorbed on the activated sludge. Released into the atmosphere, the mixture flows into the aerobic part, and the ammoniacal nitrogen adsorbed on the zeolite is oxidized to oxidized nitrogen by nitrogen oxidizing bacteria, and then circulated to the anoxic part, of A third step of removing elemental and BOD substances and regenerating the adsorption capacity of activated sludge and zeolite, a fourth step of supplying the activated sludge and zeolite regenerated in the previous step to the first contact tank, A fifth step of extracting the mixed liquid from the aerobic part of the regeneration stabilization tank and removing excess sludge.

According to a second aspect of the present invention, in the method for purifying sewage according to the first aspect, the third step and the fourth step comprise the step of: At the same time as being repeatedly circulated to the oxygen-free part, a part of the mixed solution that has passed through the oxygen-free part and the aerobic part is constituted by a step of being returned to the contact tank. .

According to a third aspect of the present invention, in the method for purifying sewage according to the first or second aspect, the fifth step intermittently draws a fixed amount of the mixed solution from the aerobic part, The method includes a step of removing contaminants by coagulating and dehydrating the mixed liquid, and supplying the dehydrator-removed liquid with reduced contaminants to a sedimentation tank again.

[0012] The sewage purification treatment apparatus according to the fourth aspect of the present invention is characterized in that activated sludge and zeolite are brought into contact with the sewage introduced into the present facility, so that the BOD contained in the sewage is improved.
The organic matter which is a substance is in the activated sludge, the ammonia nitrogen is in the contact tank adsorbing on the zeolite, and the sewage, zeolite and activated sludge mixed liquid that has passed through the contact tank is precipitated, and the supernatant liquid from which the pollutants are removed is removed. The sedimentation separation tank for discharging and separating the activated sludge and zeolite to which the organic matter and the ammonia nitrogen are respectively adsorbed, the activated sludge and the zeolite which are divided into an oxygen-free part and an aerobic part, and separated in the sedimentation separation tank After being transferred to the oxygen-free part, the organic matter and nitrogen adsorbed by the activated sludge and the zeolite are removed by circulating the oxygen-free part and the aerobic part, and the adsorption capacity of the activated sludge and the zeolite is regenerated. It is characterized by comprising a regeneration stabilization tank to be supplied to the contact tank again, and an excess sludge removing means for extracting a certain amount of the circulating liquid from the aerobic section and coagulating and dewatering.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a sewage purification apparatus according to the present invention comprises: a sedimentation tank (1) for sedimentation and sedimentation of sediment from sewage flowing in from the direction indicated by A; A contact tank (2) for bringing the sewage passed through the sedimentation tank and the activated sludge returned from the regeneration stabilization tank (4) into the zeolite charged in the E direction at the initial stage of operation into mutual contact with each other; The supernatant liquid discharged is discharged in the direction B, and a sedimentation separation tank (3) for sedimentation and separation of the zeolite and the activated sludge, an oxygen-free part (4a) provided with a stirring means (41) and an aeration means (42) has an aerobic part (4
b), the zeolite and the activated sludge settled in the sedimentation separation tank (3) are transferred to the oxygen-free part (4a) through the first pipe (11), and then the aerobic part (4c) is passed through the pipe (4c). 4
b) a regeneration stabilization tank (4) which flows into the b) and is circulated again through the second conduit (12) to the oxygen-free part (4a);
By operating the valve (16), a certain amount of the circulating fluid that has passed through the aerobic part (4b) is supplied continuously or intermittently through the third conduit (13), and the circulating fluid is aggregated and dehydrated in the D direction. And excess sludge removing means (6) for discharging the dewatered cake.

From the above, the oxygen-free part (4a) and the aerobic part (4
A part of the circulating liquid passing through b) is returned to the contact tank (2) by the operation of the pump (P1), and the excess sludge desorbed liquid in the excess sludge removing means (6) is supplied to the pump (P2). In operation, it is transferred to the sedimentation tank (1) through the fourth pipe (14).

The sewage purification method of the present invention using the above-configured apparatus will be described below.
The sewage from which sediments are settled and separated in the sedimentation tank (1) flows into the contact tank (2), and the zeolite supplied from the E direction in the initial stage of operation and the activity returned from the regeneration stabilization tank (4). The sludge passes through the contact tank (2) while being in agitated contact with each other. In this process, the ammonia ion (NH ₄ ⁺ −) contained in the sewage is discharged due to the cation exchange capacity of the zeolite.
N) is adsorbed on the porous fine-particle zeolite,
On the other hand, the organic sludge and a part of nitrogen and phosphorus components are adsorbed to the activated sludge by the adsorption ability of the activated sludge.

The mixed solution that has passed through the contact tank is settled and separated in a settling tank (3) from zeolite adsorbing ammonia nitrogen and activated sludge adsorbing organic matter, and the supernatant liquid is discharged in the B direction.

The sedimented and separated mixture of zeolite and activated sludge is transferred to an oxygen-free part (4a), and the mixture passed through the oxygen-free part (4a) flows into an aerobic part (4b), The ammoniacal nitrogen adsorbed on the zeolite in the aerobic part (4b) is oxidized to nitrite nitrogen and nitrate nitrogen by aerobic microorganisms such as Nitrosomonas and Nitrobacter. You.

The process is represented by a chemical formula as follows.

Embedded image

In the above formula, Z means zeolite, Z · N
H ₄ ⁺ represents a zeolite on which ammoniacal nitrogen is adsorbed.

The mixed solution containing the oxidized nitrogen in the aerobic part (4b) is circulated to the oxygen-free part (4a) through the second pipe (12) by the operation of the pump (P3), and the sedimentation tank (13) )
Is remixed with the mixed liquid of zeolite and activated sludge transferred to the oxygen-free part (4a). The nitrogen component is reduced to nitrogen gas by the sex denitrifying bacteria and released into the atmosphere according to the direction C, thereby removing the nitrogen component contained in the sewage.
In this denitrification operation, the organic matter adsorbed on the activated sludge is consumed, so that the organic matter is removed.

[0021] In the organic matter adsorbed on the activated sludge, the remainder not consumed in the oxygen-free part (4a) and the ammonia nitrogen adsorbed on the zeolite are transferred to the aerobic part (4b), The remaining organic matter is oxidized or assimilated in (4b), and the ammonia nitrogen is oxidized to oxidized nitrogen.

That is, by circulating through the oxygen-free part (4a) and the aerobic part (4b), the ammonia nitrogen adsorbed on the zeolite is oxidized to oxidized nitrogen, separated from the zeolite, and adsorbed on the activated sludge. Some of the organic substances, which are BOD substances, are consumed at the time of denitrification, and the rest is removed by oxidation or assimilation, so that zeolite and activated sludge regenerate their adsorption capacity.

The mixed solution containing the regenerated zeolite and the activated sludge having the adsorptive capacity is returned to the contact tank (2) through the fifth pipe (15), and brought into contact with the sewage in the contact tank.
The above process is repeated by adsorbing pollutants such as ammonia nitrogen, organic matter and phosphorus contained in the sewage.

Further, the excess activated sludge which increases in the apparatus system with the progress of the sewage treatment is transferred to the aerobic section (4b).
After continuously or intermittently transferring a certain amount of the internal circulating liquid to the surplus sludge removing means (6), this is coagulated, dewatered and disposed as a dewatered cake. It is returned to the sedimentation tank (1) through the fourth pipe (14).

As described above, the present invention utilizes a contact tank (2) for rapidly and physicochemically adsorbing and separating pollutants in sewage or sewage by utilizing the adsorption capacity of activated sludge and zeolite. The regeneration stabilization tank (4) for removing pollutants and regenerating the adsorption capacity of activated sludge and zeolite is organically connected,
It is suitably implemented as a processing method having both advantages of physicochemical and biological processing.

That is, in the conventional biological treatment method,
When removing nitrogen contained in sewage, the liquid temperature should be 15 ° C.
The treatment efficiency is extremely reduced below, and it was impossible to actually remove nitrogen from water and sewage, but according to the present invention, the pollutant component is adsorbed by a physicochemical method less affected by the liquid temperature. Since concentration and sedimentation are performed in the sedimentation separation tank (3), the pollutant and activated sludge are maintained at a high concentration in the regeneration stabilization tank (4), and the calorific value per unit volume of the regeneration stabilization tank (4) is reduced. Due to the high temperature, it is easy to maintain the liquid temperature that does not hinder microbial treatment even in winter.

Further, in the conventional biological treatment method, the fluctuation of the load of the pollutant component absolutely affects the sedimentation of the sludge in the final sedimentation tank. Of the activated sludge is transferred to the sedimentation tank (3) together with the zeolite having a high specific gravity, so that the sedimentation property is extremely improved, the influence of the load fluctuation of the pollutant component of the inflow sewage is small, and in the contact tank (2), Since the pollutants are removed by physical adsorption, the treatment efficiency is good even when the concentration of the pollutants is low.

The present invention also provides a method for physicochemically adsorbing and concentrating pollutants in a short period of time in a contact tank (2) and subjecting the contaminants to biological regeneration in a regeneration stabilization tank (4) maintained at a high concentration of microorganisms. Therefore, the sum of the tank volumes of the contact tank (2) and the regeneration stabilization tank (4) can be greatly reduced as compared with the conventional aeration tank volume. In addition, zeolite automatically regenerates its adsorption capacity through biological nitrogen removal processes such as nitrogen oxidation and denitrification, eliminating the need for additional equipment and chemicals for zeolite regeneration. It is more economical and easier to maintain than the regeneration method.

Particularly, in the case of regenerating zeolite with a chemical, complicated equipment and operation management are required for the treatment of regenerated waste liquid and ammonia gas, and exchange of degraded zeolite by repeating adsorption and regeneration for a certain period using a zeolite packed tower is required. However, in the present invention, zeolite corresponding to the amount of zeolite discharged together with the excess sludge may be charged and replenished in the contact tank.

As an organic carbon source required in the denitrification step, an organic substance adsorbed on activated sludge can be used, so that a chemical such as methanol can be eliminated or reduced, and a solid retention time (SRT: Solid Retention) can be used. By adjusting the time, it is possible to adjust the amount of zeolite input, and operation management costs can be reduced.

[0031]

According to the present invention, the pollutants contained in domestic sewage or sewage discharged from homes or factories are adsorbed on zeolite and activated sludge, and the ammonia nitrogen adsorbed on the zeolite is subjected to aerobic conditions. The zeolite is regenerated by being oxidized to oxidized nitrogen at the same time, while the oxidized nitrogen is finally reduced to nitrogen gas and released under anoxic condition. As an organic carbon source required in the process of denitrifying oxidized nitrogen, an organic substance as a BOD substance adsorbed on activated sludge can be applied, and therefore, simultaneous removal of an organic substance as a pollutant and nitrogen is achieved.

In addition, nitrogen can be removed even when the liquid temperature decreases in winter, and there is an effect that it is easy to cope with fluctuations in the pollution load.

Further, according to the present invention, even when the concentration of pollutants is low, the purification efficiency is high, the volume of the tank can be reduced, the purification equipment can be simplified, the operation management is simple, and the management is simple. It also contributes to lower costs.

[Brief description of the drawings]

FIG. 1 is a schematic view of a sewage purification treatment apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sedimentation tank 2 Contact tank 3 Sedimentation separation tank 4 Regeneration stabilization tank 4a Oxygen-free part 4b Aerobic part 6 Excess sludge removal means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 3/34 101 C02F 1/28 C02F 3/12

Claims (4)

(57) [Claims] 1. A first step in which organic substances as BOD substances contained in sewage are adsorbed and removed in activated sludge and ammoniacal nitrogen is adsorbed and removed in zeolite by passing through a contact tank, and an organic substance in sewage passed through the contact tank. The activated sludge and zeolite that have respectively adsorbed ammonia and ammonia nitrogen are settled and separated, and the supernatant liquid from which the pollutant component has been removed is discharged. The activated sludge and zeolite that have settled and separated are anoxic and aerobic. The oxygen is transferred to the oxygen-free part of the regeneration stabilization tank and mixed with the internal circulating liquid containing oxidized nitrogen circulated from the aerobic part, and the oxidized nitrogen in the circulated liquid is adsorbed by the activated sludge. Reduced by the action of denitrifying bacteria using organic substances to nitrogen gas and released into the atmosphere, the mixture flows into the aerobic part,
The ammoniacal nitrogen adsorbed on the zeolite is oxidized to oxidized nitrogen by nitrogen oxidizing bacteria and then circulated to the anoxic part to remove nitrogen and BOD substances in the sewage and regenerate the adsorption capacity of activated sludge and zeolite. A third step of supplying the activated sludge and zeolite regenerated in the previous step to the contact tank of the first step; and withdrawing the mixed liquid from the aerobic part of the regeneration stabilization tank to remove excess sludge. A sewage purification method comprising: a fifth step of removing. 2. The sewage purification method according to claim 1, wherein the third step and the fourth step are such that the mixed solution passing through the oxygen-free part and the aerobic part is repeated to the oxygen-free part. And a part of the mixed liquid that has passed through the oxygen-free part and the aerobic part while being circulated is returned to the contact tank. 3. The method for purifying sewage according to claim 1, wherein the fifth step includes intermittently withdrawing a certain amount of the mixed solution from the aerobic part, and coagulating and dehydrating the mixed solution. A method of purifying sewage, comprising the step of removing pollutants by performing treatment and supplying the dehydrator desorbed liquid having reduced pollutants to a sedimentation tank again. 4. The activated sludge and the zeolite are brought into contact with each other, so that the organic matter as a BOD substance contained in the sewage passes through the activated sludge and the ammonia nitrogen passes through the contact tank adsorbed on the zeolite. The sediment mixture containing sewerage, zeolite and activated sludge is settled, the supernatant liquid from which pollutants are removed is discharged, and a sedimentation separation tank for sedimenting and separating activated sludge and zeolite, to which organic matter and ammonia nitrogen are respectively adsorbed, After the activated sludge and zeolite separated in the sedimentation separation tank are transferred to the oxygen-free part, the activated sludge and zeolite are adsorbed by circulating the oxygen-free part and the aerobic part. The activated sludge and the zeolite are regenerated by removing the organic matter and nitrogen contained therein, and the regeneration stabilization tank supplies these to the contact tank again. Purifying apparatus of the sewage, characterized in that it is composed of a excess sludge removal means for aggregating dewatering withdrawal amount.