JP4354468B2 - Water splitting method and water splitting device - Google Patents

Description

  The present invention mainly relates to a sewage treatment, in particular, a water splitting method implemented in addition to a step inflow multistage nitrification denitrification process and a water splitting device used in the method.

  In sewage treatment, the need for advanced treatment is increasing. For this reason, the present applicant has also developed various advanced treatment processes including the “step inflow multi-stage nitrification denitrification process”.

  The "step inflow multi-stage nitrification denitrification process" is a high-performance advanced treatment process that has been introduced in many cases. However, it is assumed that the inflow water is usually divided into three equal parts and step-in from the first stage to the third stage. It is a processing process.

Japanese Patent No. 3718180

  In the practice of the invention, in actual operation, it is not so difficult to divide the flow rate into two equal parts by adjusting the weir height in the diversion tank, but it is not easy to divide the flow equally into three parts. Even if the weir height is adjusted so as to be divided, it is known that if the water level changes due to the fluctuation of the flow rate, there is a considerable difference in the divided flow rates.

  In the step inflow multi-stage nitrification denitrification process, the facility design is based on the premise that the inflow water is divided and supplied evenly, so the inflow water is not evenly distributed. It has been pointed out that when the MLSS concentration and the residence time are different from the set operation, an undesirable effect on nitrogen and phosphorus removal occurs.

  The equal division of the inflowing water amount can be performed by measuring with a sensor and controlling with an electric weir, but this has the problem of high installation costs and maintenance costs. For this reason, it has been desired to develop a water splitting method and apparatus capable of stable three divisions regardless of flow rate fluctuations.

  The present invention is a water distribution and a device therefor having a function of equalizing a flow rate difference at the time of division by a method of further dividing the inflow water once divided by a weir or the like and then joining the divided water again.

  FIG. 1 shows the principle. In FIG. 1, first, inflow water is divided into three parts by a weir or the like. (Part A) Thereafter, the inflow water divided into three parts is further divided into two equal parts by a weir or the like. Further, the influent water divided into two equal parts is joined again. The three flows after the merge are finally divided into three.

That is, the gist of the present invention is as follows.
Dividing the inflow water into three parts by the weirs, then dividing the three inflows into two parts, then joining the two parts of the inflowing water, respectively, and flowing the three flows after joining into the water channel respectively The influent water is divided into three divided tanks through three overflow dams in the water channel, and then the influent water is merged into each merging tank through two overflow dams in each three divided tank. It is a diversion device that flows into each water channel through overflow weirs.

  According to the present invention, it is possible to reduce the mutual difference in flow rate due to the fluctuation of the water level without using a measurement / control device or power in the three equal parts of the inflowing water amount.

  As an example, let us consider a case where the weir height is adjusted so that a total of 30 flow rates are divided into three parts of 10. However, it is assumed that there is a large difference in the actual amount of split water due to factors such as fluctuations in the water level, and a = 13, b = 11, and c = 6.

  When this is divided into two equal parts and merged again, the outflow amount from the apparatus becomes the numerical value shown in Table 1. As shown in Table 1, it can be seen that the difference between the flow rates ((1), (2), (3)) by the apparatus of the present invention is smaller than that at the time of inflow. In addition, in order to further reduce the error, Table 1 also shows the outflow amount when the above-described water amount (a = 13) was introduced into this water splitting device in two stages in series. When two stages are connected in series, it is understood that the mutual difference is further reduced, and the flow rate is close to equal division.

  With the above effects, it is possible to operate under the preconditions in the step inflow multi-stage nitrification / denitrification process design, and stable and good nitrogen / phosphorus removal is possible.

The use of the water separator according to the present invention is not limited to the field of sewage treatment, and can be widely used for the purpose of flow distribution. Furthermore, the present invention can be applied to four or more divisions.
Further, the mathematical basis of the principle of the present invention will be described below.

There are three numbers, all of which are x. In this case, a, b, and c each take a positive or negative value, and the total amount of change is zero. (a + b + c = 0)
The changed values are x + a, x + b, and x + c, respectively.
Dividing these three numbers into two equal parts;

  Combining (1), (2), and (3) by two terms

  Here, since a + b + c = 0 from the assumption,

  Substituting (7), (8), and (9) into (4), (5), and (6), respectively

  here,

  Therefore, the change amounts of (10), (11), and (12) are smaller than the change amounts a, b, and c of x + a, x + b, and x + c.

  Hereinafter, the present invention will be described based on disclosed embodiments. The water diversion device shown in FIGS. 2 to 4 has a rectangular shape, the water channel 1 is composed of an open channel and a pipe, and the first overflow weirs 2 open toward the first storage tank 3 with a required interval in the water channel 1. ing.

The first overflow weir 2 can be formed of a fixed weir, a movable weir, an orifice, or the like.
Each first storage tank 3 has a pair of second overflow weirs 2 that open toward the second storage tank 4. In the second storage tank 4, third overflow weirs 2 are opened at required water channels, for example, steps to a sewage treatment tank.

  The water diverter shown in FIG. 5 has a circular shape, and has a water channel 2 at the center, a first storage tank 3 is disposed in the periphery thereof, a second storage tank 4 is disposed on the outside thereof, and the water channel 2 and the first storage tank 3. The overflow weirs 2 are opened between the first storage tank 3, the second storage tank, and the second storage tank 3.

  FIG. 6 shows the method and arrangement of the step inflow multi-stage nitrification denitrification process in which the method and apparatus of the present invention are implemented. A plurality of stages of denitrification tank B and nitrification tank C are arranged in series, and the raw water is supplied to this stage. Equally distributed to each denitrification tank B through the water diverter A of the invention, provided with tank capacity so that the amount of solids at each stage is equal, and returned sludge from the final sedimentation basin E where the internal circulation D of the liquid mixture by air lift is made Will be returned.

  The water flow that has passed through the overflow weirs 2 of the second storage tank 4 of the water diverter A is drained into the denitrification tanks B through the flow channels 5. And, in the step inflow multi-stage nitrification denitrification method, if the inflow water amount is not divided equally, the sludge concentration in each stage will change, so this invention solves the problem that the solid amount of each stage is not equal to the design assumption it can.

The outline of the present invention is illustrated. It is the top view which showed the arrangement | positioning state of the apparatus of this invention. It is II sectional drawing of FIG. It is II-II sectional drawing of FIG. It is the top view which showed the outline | summary of the other Example of this invention. It is a schematic diagram of the state of a sewage treatment using the apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Water channel A ... Divider 2 ... Overflow weir B ... Denitrification tank 3 ... First storage tank C ... Nitrification tank 4 ... Second storage tank D ... Internal circulation 5 ... Water channel E ... Final sedimentation tank
F ... Return sludge

Claims (2)

  The inflowing water is divided into three parts by weirs, then the three parts of the inflowing water are divided into two parts, then the two divided inflowing waters are joined together, and the three flows after joining are each flowed into each water channel Water splitting method. The influent water is divided into three division tanks through the three overflow weirs in the waterway, and then the inflow water is merged into each merge tank through the two overflow weirs in each three division tank. A water diverter characterized by flowing into each water channel through flow weirs.

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