JPS602917B2 - Biological treatment method for wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a wastewater biology method that biologically purifies wastewater such as sewage, urine and urine, product wastewater, and waste physical leachate containing pollutants such as organic compounds and nitrogen compounds. This relates to a processing method.

More specifically, BOD is caused by microorganisms contained in sludge.
A method for oxidative decomposition of components (BOD components → carbon dioxide, water), nitrification (ammonia nitrogen → nitrate nitrogen, nitrite nitrogen) and denitrification (nitrate nitrogen, nitrite terrestrial nitrogen → nitrogen gas), and its It is a device that maintains two reaction tanks in an aerobic state (
The present invention relates to a biological treatment method for wastewater, which is characterized by switching between a state in which oxygen is present) and an anaerobic state (a state in which oxygen is absent). Conventionally, in the purification of sewage and other sewage, especially with regard to biological treatment of nitrogen components, sewage and other wastewater has been treated with activated sludge and other secondary treatments to reduce BOD.
After or without removing the components, the anaerobic tank and the nitrous solution are arranged in one or more series, in a positive or negative manner, and some of the liquid in the anaerobic or aerobic treatment is Recycling methods have been proposed in which the waste is returned to the process.

According to these methods, for example, as shown in Fig. 1, a plurality of independent slags are installed separately from the activated sludge treatment tank a (warming tank), namely settling tanks b and c, nitrification tank d, and denitrification tank. e,
A reaeration tank h is required, and sludge return must be carried out separately and independently. In addition, in nitrification, it is necessary to add an agent to control alkalinity (f is an alkali supply tank) or an organic carbon source that is a hydrogen acceptor such as methanol in a denitrification tank (g is a methanol addition tank).
However, there were disadvantages such as high construction and operating costs, and complicated and time-consuming operation and maintenance, which hindered its practical application. In this situation, Samurai Seki 49
As shown in Publication No. 51767, two or more reaction tanks are transported, switching of raw water, utilization of reaction treated water from the reaction tank connected to the final sedimentation tank, and control of each reaction tank. A method has been proposed for biologically purifying nitrogen components by circulating and repeating unit operations of systems such as Kirifusuma in aerobic and anaerobic conditions.

However, even with this proposal, after the anaerobic treatment, the aerobic condition is aerated in a closed condition or sedimentation treatment is carried out, and then,
Since the water quality of the reaction treated water is tracked over time, it can be seen that when the aerobic atmosphere is excessive or when only anaerobic atmosphere treatment is performed, the raw water is There is a drawback that the nitrate component does not receive sufficient aerobic and anaerobic conditions, and the nitric acid component takes a short path and flows out without being reduced to nitrogen, resulting in a decrease in the nitrogen component removal rate. Even more inconveniently, it is unavoidable to reduce temporal fluctuations in the quality of the reaction-treated water, resulting in the production of non-uniform treated water. In particular, when fluctuations in nitrogen components and 80D components and disturbances in load fluctuations in water amount are large, there is a problem in that the treatment effect is significantly inhibited. In addition, the method disclosed in Hakama Seki Publication No. 49-51767 involves providing a weir in each tank and raising or lowering the weir to allow the treated water to flow between the tanks, or to distribute the treated water between the tanks. This poses a problem in that the operation and operation are complicated because the system halts the distribution of products. The present inventors have conducted intensive research to solve the drawbacks of the method of decomposing and purifying nitrogen components, 80D components, COD components, etc. in wastewater using the plurality of switchable reaction tanks, and as a result, they have developed the present invention. It was completed.

The present invention connects two reaction tanks for biologically purifying sewage, alternately switches the raw water (sewage) inlet to make one reaction tank anaerobic or aerobic, and the other In a biological treatment method for wastewater in which the reaction vessels are brought into an aerobic state or an anaerobic state and a settling tank is connected to the two reaction vessels, [1' Raw water is supplied to one reaction tank and the reaction is carried out. A step of bringing the tank into an anaerobic state and the other reaction tank into an aerobic state and introducing the reaction treated water from the other reaction tank into the sedimentation tank, ``2'' Supplying raw water to one reaction tank and turning this reaction tank. A step of introducing the reaction treated water from the other reaction tank into the sedimentation tank with the other reaction tank also in the aerobic state, '3' between one reaction tank and the other reaction tank, A method that can uniformly purify wastewater with simple operations without providing a weir that can be raised and lowered by at least including a step of constantly circulating reaction treated water between a tank and a settling tank. We aim to provide the following.

That is, the present invention, as shown in FIG. In a sewage purification device that is connected to a supply tank 5 and to a settling tank 3 via another switching valve 6, sewage is supplied to the reaction tank 1 during a certain period of time, and during the same period, the reaction treated water is The treated water is discharged from the outlet of the reaction tank 2 which is not receiving waste water supply by connecting it to the sedimentation tank 3, and in each reaction tank, when providing an aerobic atmosphere or (and) an anaerobic atmosphere, (1) Switching is made so that the sewage water is introduced into one of the tanks, and the reaction treated water is discharged from the other tank to the sedimentation tank; ■ The aerobic atmosphere and anaerobic atmosphere are switched in both reaction tanks. , '3} The reaction tank connected to the settling tank must always be in an aerobic atmosphere, [4' The sewage supply in both reaction tanks, the state of connection to the settling tank, and the state of aerobic and anaerobic atmospheres. , the time order is the same, and the form is repeated in a certain period of time, and the phase for one circulation unit is 1 in the conditions of both reaction vessels.
/2 deviation.

In FIG. 2, 7 indicates a transportation pipe, and 8 indicates a return sludge pipe. Hereinafter, the configuration of the present invention will be explained in detail based on embodiments shown in the drawings.

FIG. 3 shows a sewage treatment apparatus implementing the method of the present invention. 1 is a first reaction tank, 2 is a second reaction tank, and each of these reaction tanks 1 and 2 has a rope tensioning means 10, 1 1 inside.
and air blowing means 12, 13 if < is oxygen blowing means (
Hereinafter, air blowing means 12 and 13) are provided as independent or integrated mechanisms.

The reaction vessels 1 and 2 and the raw water inlets 14 and 15 are switchably connected to a raw water supply pipe 16 via a three-way switching valve 4. Further, the reaction treated water outlets 17 and 18 of the reaction tanks 1 and 2 are connected to the sedimentation tank 3 via switching valves 6a and 6b so as to be freely switchable.
Further, both the reaction vessels 1 and 2 are connected to each other through a passage pipe 7. The equipment attached to both reaction tanks is 2 river blowers, 21 is a raw water supply pump, 22 is an initial settling tank, 23 is a mixing tank, 24 is a treated water receiving tank, 25 is a return sludge pump, and 26 is a surplus tank. It is a sludge pump. When the inside of the reaction tank is brought into an aerobic state, the blower 20 is driven to perform aeration. To make the inside of the reaction tank anaerobic, stop the aeration and mix and suspend the sludge in the water in the tank using rope means such as propellers, turbine blades, paddle blades, star blades, and portal blades. urge Another method of anaerobic and aerobic treatment is to use a Kessner brush, a water wheel type aerator, etc. to operate the aerator at high speed to obtain an aerobic state, and to operate at a low speed to obtain an anaerobic state. can do. Further, by changing the infiltration water level of this aerator, the anaerobic or aerobic atmosphere may be changed as appropriate. In an aerobic atmosphere, air, oxygen, or an oxygen-containing gas is used for aeration. In the apparatus constructed as described above, an embodiment of the operating state of the reaction tank will be described with reference to FIG.

The shaded area indicates the anaerobic condition, and the blank area indicates the aerobic condition. First, as shown in FIG. 4 1, a cut valve is operated in tank 1 to supply raw water to bring tank 1 into an anaerobic state. In the tank 1, denitrification is carried out using the BOD component in the wastewater as an organic carbon source. That is, the reaction of 2MM Misaki (Bo position) (board @ N2 10 Misaki 20 120H - 20H - 10 H - 10 (BOD component)) --- 1 N2 0 is 20 12 N 〇 evening is performed.

On the other hand, the rice cake 2 is connected to a sedimentation tank in an aerobic state, and reaction treated water is introduced therein. In the tank 2, oxidation of BOD components and nitrification of ammonia nitrogen are carried out. Next, as shown in FIG. 4, the rice cake 1 is in an aerobic state and the rice cake 2 is in an aerobic state, that is, both tanks are in an aerobic pillow state, and the rice cake 2 is connected to a sedimentation tank, and the reaction treated water is introduced. In the tanks 1 and 2, oxidation of BOD components and nitrification of ammonia nitrogen are carried out as described below. BOD component (CxHy gong) 102
-1 C02 10th 20N Review 2 -1 N
As shown in Figure 4, 3, the tank 1 was placed in an anaerobic condition, the tank 2 was placed in an aerobic condition, and tank 2 was connected to the sedimentation tank, i.e., the same condition as in Figure 4 1 was established. By returning it, the denitrification reaction in the rice cake 1 is completed.

In tank 2, oxidation of BOD components and nitrification of ammonia nitrogen are performed. Thereafter, as shown in FIG. 4, the sewage supply is switched to the tank 2, and the tower 2 is placed in an anaerobic state, and the tank 1 is set in an aerobic state and connected to the sedimentation tank. In other words, the state shown in FIG. 41 is exactly reversed, and denitrification of nitrate nitrogen is carried out in the cage 2, and oxidation of BOD components and nitrification of ammonia nitrogen are carried out in the cage 1. Next, as shown in FIG. 4, tank 1 is connected to the sedimentation tank with tank 2 in an aerobic state and tank 1 in an aerobic state, that is, both towers in an aerobic state. Oxidation of BOD components and nitrification of ammonia nitrogen take place in the cassettes 1 and 2. Next, as shown in FIG.
Condition: Cement 1 is connected to a sedimentation tank in an aerobic condition. That is, by returning to the same state as in FIG. 4, the denitrification reaction in the rice cake 2 is completed. In the pot 1, oxidation of the 80D component and nitrification of ammonia nitrogen take place. Thereafter, the raw water (sewage) inlet is switched to supply sewage to the tank 1, and the series of operations shown in FIGS. 1 to 6 are repeated. The embodiment described above consists of a 6-time phase cycle, but there are also 4-time phase cycles as shown in FIG. 5, 6-time phase cycles as shown in FIG. 6, and 6-time phase cycles as shown in FIG. It is also possible to use an 8-temporal cycle or the like. Note that FIGS. 5 to 7 show examples of preferred embodiments, and the present invention is not limited thereto. In the treatment method of the present invention, the reaction tanks 1 and 2 are always fragrant, so that the wastewater can be uniformly subjected to reaction treatment in both reaction tanks.

Therefore, it is possible to cope with fluctuations in nitrogen components and BOD components, and fluctuations in water volume load. In addition, as mentioned above, the BOD component in raw sewage is used as an organic carbon source for denitrifying bacteria necessary for the denitrification process, but if necessary, methanol, acetic acid, formic acid, etc.
The denitrification reaction may be made more active by appropriately adding and combining general organic carbon sources such as acetone and saccharides. In the treatment method of the present invention, it is preferable that the aerobic and anaerobic conditions are repeated substantially once or more, or several times on average, in a fixed cycle unit, in view of the entire flow of water.

Therefore, the average residence time in both reaction vessels is preferably 0.5 to 2 times, preferably 1 to 5 times, the unit period of paddy exchange circulation.
If it is in a range other than this, the reaction of NH;, NQ- will not be sufficient, and complete denitrification performance will not be obtained. Further, for example, the time allocation for each unit step in one circulation system may be appropriately selected in order to optimally set the anaerobic and aerobic processing conditions. For example, the first time phase t time, the second time phase 1'2t time, the third time phase 1/2t time, the fourth time phase t time, the fifth time phase 1/2t time, the sixth time phase 1/2t time Examples include: At this time, the overall average residence time T of water treated in both reactions is T = 4t, and this time T is 2
~20 hours (depending on temperature, concentration, etc.) is appropriate. In addition, the BOD component/N ratio of raw water is 2 or more, preferably 5.
The above is good. Below this value, there is a shortage of organic carbon sources necessary for denitrification of nitrate nitrogen, so it is desirable to add organic carbon sources such as methanol to the anaerobic tank. In the present invention, denitrifying bacteria, nitrifying bacteria, and 800-component oxidizing bacteria operate based on anaerobic and aerobic conditions, adapting to the given environment such as the amount of oxygen present in water, temperature, and food. Therefore, it is desirable that the unit action time phase of anaerobic and aerobic activities be at least about 2 minutes. According to the present invention, this treatment is possible without the need for adding methanol, which is an organic carbon source for denitrifying bacteria, which is required in conventional denitrification methods.
In addition, it is only necessary to have two reaction tanks and one sedimentation tank as equipment, so compared to the conventional system such as activated sludge treatment process, nitrification process, and denitrification process, it is especially necessary to use a denitrification tank and a nitrification tank. Since there is no need to provide a reaction tank, the number of device configurations is small and the structure is simple.

In addition, according to the present invention, the removal of BOD components, COD components, and nitrogen can be achieved simultaneously, and an organic carbon source such as methanol is not essential, so that resource and energy savings can be achieved. Since BOD and COD components are effectively used during denitrification, the amount of surplus sludge generated can be reduced by 20%.
To a lesser extent, sludge treatment becomes extremely easy. Furthermore, in response to changes in water quality and load, the switching time of the reaction tank can be changed freely, allowing for flexible response to the inflow load amount, and both reaction tanks are connected to each other so that water is constantly flowing. As a result, wastewater is treated uniformly with both reaction vessels. That is, in the present invention, since the distance between the two tanks is always suitable, it is possible to suppress as much as possible the short path of concentrated ammonia nitrogen contained in the inflowing wastewater to the treated water, and to make load fluctuations uniform. Can be done.

In addition to these effects, the rate at which inflowing sewage is treated by both tanks is the same as that of Hakama Kaisho 49-51767.
This is larger than the non-commercial method described in the publication, and therefore contributes to homogenization of processing.

'b' Equipped with an adjustment function to homogenize incoming sewage over time and load fluctuations.

'c' Since the amount of MLSS and the amount of pollution in both tanks are equal, the load factor is also stable.

According to the present invention, at least 95% of BOD and 90% or more of ammonia, organic, nitrate, and nitrate nitrogen are removed, and bulking factor (S
VI) can always be kept below 150, and the removal effect at low temperatures is also remarkable.

Examples of the present invention will be described below.

Example Two containers of 30 units each equipped with a Honnakahashi machine and a diffuser type aerator were connected to a conical sedimentation tank of 20 units as shown in Figure 2, and domestic wastewater was inflowed at a rate of 5 units/h. The treatment was then carried out according to the process shown in FIG. 4, with an average residence time of 1 hour for both tanks combined.

The conditions and results were as follows. Raw water properties B
OD component 30Q wind, total nitrogen 4■ fence, SS120 legs, PH
7. &Water temperature 220 setting conditions Sludge MBS load 0.1k9B
OD/SSk9day, MLSS400Q Nada switching state Residence time in each reaction chamber 6 hours, 1st time phase interval, 2nd time phase 0.5 hour, 3rd time phase 0. Between insect cages, 4th phase 1 hour, 5th phase 0. Song time, 6th phase 0. Average water quality of immediately treated water BOD components: 7 (removal rate: %) Total nitrogen: 1 (removal rate: 97%) SVI: 90 Comparative Example For comparison, the same raw water as above was prepared using the conventional equipment shown in Figure 1. Processed.

The conditions and results were as follows. Setting Conditions Treated water containing 25 traces of BOD components, 70 traces of SS, and 30 traces of total nitrogen was obtained in advance by the usual activated sludge method, and using this, the process shown in Figure 1 was carried out.

Nitrification tank M mountain SS300Q wind, N load 0.1kg/reda
y, pH 83 (alkali addition) denitrification Myama SS3000
Legs, metal/-le addition C/N=3, N load lk9/〆da
yWater quality of treated water BOD component IQ Blood (removal rate 60%) Total nitrogen 8 legs (removal rate 73%) SVI 140 As is clear from the above results, the method of the present invention has better nitrogen removal and BOD content than the conventional method. It shows good treatment effects in terms of component removal.

Brief description of the drawings: Fig. 1 is an explanatory diagram showing an example of a wastewater treatment bag hawk according to the conventional method, Fig. 2 is an explanatory diagram showing an outline of an apparatus for carrying out the method of the present invention, and Fig. 3 is an explanatory diagram showing an example of a wastewater treatment bag hawk according to the conventional method. FIG. 4 is an explanatory diagram showing one embodiment of the operating state of the reaction tank in the present invention, and FIGS. FIG. 6 is an explanatory diagram showing another embodiment of the operating state.

Note that the shaded area indicates the anaerobic condition, the blank area indicates the aerobic condition, and the arrow indicates the direction of water flow. 1, 2... Reaction tank, 3... Sedimentation tank, 4... Switching valve, 5...
...Sewage supply tank, 6.6a, 6b...Switching valve, 7...Communication pipe, 8...Return sludge pipe,
10, 11... Fly Azusa Means, 12, 13...
Air blowing means, 14, 15... Raw water inlet, 16...
...Raw water supply g-plex pipe, 17.18...Reaction treated water outlet, 20...Fake air blower, 21...Raw water supply building pump, 22... First sedimentation tank, 23...
... Mixing tank, 24 ... Treated water receiving tank, 25 ...
...Return sludge pump, 26... Surplus sludge pump.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 Two reaction tanks for biologically purifying wastewater are connected to each other, and the raw water inlet is switched alternately to put one reaction tank in an anaerobic state or an aerobic state, and the other reactor in an aerobic state. Alternatively, in a biological treatment method for wastewater in which a sedimentation tank is connected to two reaction tanks in an anaerobic state, (1
) Supplying raw water to one reaction tank to make this reaction tank an anaerobic state, and making the other reaction tank an aerobic state and introducing the reaction treated water from this other reaction tank to the sedimentation tank, (2) one of the reaction tanks. Supplying raw water to the reaction tank to make this reaction tank an aerobic state, and also making the other reaction tank an aerobic state, introducing the reaction treated water from the other reaction tank into the sedimentation tank, (3) one reaction tank and 1. A biological treatment method for sewage comprising at least the step of constantly circulating reaction treated water between the other reaction tank and between the other reaction tank and the sedimentation tank.