JP2002113470A - Method and apparatus for high speed filtration/ separation of solid-suspended water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel high speed solid-liquid separation technology which solves conventional problems and can prevent the outflow of SS into treated water even at a high solid-liquid separation speed. SOLUTION: In a method for the high speed filtration/separation of solid- suspended water, after magnetic particles and a flocculant are added into raw water to form a magnetic flock, the mixed raw water is passed through a layer filled with granular filter medium at least 80% in initial porosity in an ascending current, and the flock containing the magnetic particles is filtered/ separated in the layer. A high speed filtration/separation apparatus has a flocculation tank in which the magnetic particles and the flocculant are added, a filter tank in which the layer filled with the granular filter medium at least 80% in initial porosity is formed, and a magnetic particle recovery part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for high-speed filtration and separation of various types of suspension water, for example, sewage, raw water for purified water treatment, industrial wastewater, etc., and more particularly to a method and an apparatus for high-speed filtration and turbidity of suspension water.

[0002]

2. Description of the Related Art Conventionally, for example, a "new high-speed treatment process for sewage overflow water" [Wat. Sci. Tech. No.
3-4, pp. 103 to 109 (1996)], discloses a high-speed precipitation method in which magnetic particles such as magnetite and a coagulant are added to raw water and then coagulated and precipitated at a high speed.

[0003]

However, in the conventional treatment method, since solid-liquid separation is performed by the sedimentation means, finer SS flows into the treated water as the sedimentation separation speed is increased. And the sedimentation velocity was not so high. It is an object of the present invention to solve the conventional problems as described above and to provide a novel high-speed solid-liquid separation technology in which SS hardly flows into treated water even at an extremely high solid-liquid separation speed. .

[0004]

The present invention has solved the above-mentioned problems by the following means. (1) After adding magnetic particles and a flocculant to raw water to form a magnetic particle-containing floc, water is passed in an upward flow through a granular filter medium packed bed having an initial porosity of 80% or more to form a magnetic particle-containing floc. A high-speed filtration and separation method of suspended water, wherein the filtration is performed in a filter packed bed. (2) A flocculation tank for adding a flocculant and magnetic particles to raw water for flocculation, forming a granular filter medium packed layer having an initial porosity of 80% or more inside the flocculation tank, and performing a flocculation treatment from the flocculation tank through an inlet pipe provided below. Flowing water as an upward flow into the granular filter medium packed bed, draining the treated water from the upper part, a filtration tank having a discharge pipe for discharging sludge at the time of washing, introducing sludge from the discharge pipe at the time of washing the filtration tank, magnetic particles A high-speed filtration / separation device for suspension water, comprising: a magnetic particle collection section for separating magnetic particles into sludge and collecting magnetic particles; and a circulation pipe for supplying the recovered magnetic particles from the magnetic particle collection section to raw water.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a system diagram showing a high-speed filtration and separation method of suspension water of the present invention and an embodiment of an apparatus for performing the method. Raw water 1 containing suspended solids such as sewage, etc., as inorganic coagulant 3, PAC, sulfate band, ferric chloride, etc., and fine magnetic particles 4 made into permanent magnets, such as magnetite, ferrite, magnetite, etc. Ferromagnetic particles are added, and a polymer flocculant 5 (preferably anionic or nonionic polyacrylamide) is further added, and the mixture is stirred for several minutes in a flocculation tank 6. The turbidity in the raw water 1 and the magnetic particles 4 are taken into the flocs of iron oxide or the like, and a floc in an integrated state (this is called a magnetic floc) is formed.

The raw water 1 containing the magnetic floc in this state is
When water flows upward through the granular filter medium-filled layer 9 having a high porosity formed in the sections partitioned by the meshes 10 and 10 in the filtration tank 8, the magnetic floc is effectively applied to the voids of the granular filter medium-filled layer 9. The trapped magnetic flocs are magnetically agglomerated with each other, so even in the case of a very large upward water flow, the small flocs are separated from the filter medium void by the shear force of the upward water flow. , It was recognized that there was no leakage into the treated water. As a result, clear treated water 12 flows out of the outflow pipe 11 above the granular filter medium packed bed 9. In addition, the filtration tank 8 includes a cylindrical one such as a column. If the particle size of the magnetic particles 4 is too large, they will not be taken into the flocs, and if it is too small, unagglomerated particles will remain. Also,
The degree of magnetization of the magnetic particles 4 is preferably as large as possible.
It is good to be 0 gauss or more. A preferable range of the addition amount of the magnetic particles 4 is about 10 to 100 mg / liter because the degree of magnetic aggregation is reduced when the amount is too small, and the granular filter medium filling layer 9 is easily clogged when the amount is too large.

As a material of the granular filter medium, a granular filter medium made of a lightweight plastic having a specific gravity of about 1 is preferable, and a particularly preferable one has a specific gravity of 0.8 to 8 which does not require a support floor below the packed bed 9.
A buoyant particulate filter medium of about 0.95 can be used. Also,
Since the SS of the raw water 1 is increased by the addition of the magnetic particles 4, the granular filter medium packed layer 9 has a porosity of 80% or more of a granular filter medium (for example, a hollow cylindrical granular material).
This is preferable for the present invention because the amount of trapped SS can be increased and the filtration resistance can be reduced. If the particle size of the filter medium is too small, the filtration resistance of the granular filter medium packed layer 9 tends to increase, and if it is too large, the SS easily leaks into the treated water, so the particle size of the granular filter medium is 4 mm to 30 mm.
The degree is a preferable range.

In the present invention, the direction of flow of the raw water 1 in the granular filter medium packed bed 9 is important, and it is important to make the raw water 1 flow upward. That is, the magnetic flocs trapped in the voids of the granular filter medium packed layer 9 are magnetically aggregated and have very large sedimentation properties. There is no possibility that the magnetic floc that has been lost loses the upward flow velocity and carries over the treated water 12. On the other hand, when the flow direction of the raw water 1 is set to the downward flow, the sedimentability of the raw water 1 and the downward flow velocity of the raw water 1 are added to the magnetic floc, so that the magnetic floc easily leaks to the treated water, which is not preferable. .

When the apparatus of the present invention is operated in the above-described manner, the filtration resistance of the granular filter medium packed bed 9 reaches a limit or the SS of the treated water 5 increases after a lapse of a predetermined time. At this point, the inflow of the raw water 1 is stopped and the granular filter medium packed bed 9 is washed. The length of the predetermined time depends on the properties of the incoming coagulation water and the properties of the granular filter medium. The cleaning of the granular filter medium packed bed 9 of the present invention is simple,
When the valve 15 of the sludge discharge pipe 14 below the granular filter medium packed layer 9 is opened and the sludge is discharged in a large downward flow, the magnetic floc trapped in the voids of the granular filter medium packed layer 9 is deposited on the bottom of the filtration tank 8 and the like. Together with the accumulated sludge, the sludge flows out of the device in the filtration tank 8 and flows into the magnetic particle recovery unit 16. The sludge containing the magnetic floc that has flowed into the magnetic particle collection unit 16 is separated into collected magnetic particles 17 and sludge 18 here. The collected magnetic particles 17 are supplied to the supply pipe 2 of the raw water 1 by the circulation pipe 19, and the sludge 18 Transfer to sludge treatment process.

Since the washing of the granular filter medium packed bed 9 is completed only by performing this operation, the raw water to which the inorganic coagulant 3 and the magnetic particles 4 are added to the raw water 1 is supplied to the granular filter medium packed bed 9 again. Then, the clear treated water 12 flows out of the outflow pipe 11 promptly. Since the magnetic particles 4 are contained in the sludge discharged by the washing of the granular filter medium packed bed 9, the sludge is collected by a classifier using a cyclone (not shown) or a magnetic separator using a magnet, and circulated as the collected magnetic particles 17. The raw water 1 is recycled from the pipe 19 to the supply pipe 2 of the raw water 1.

[0011]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited by these examples.

Example 1 Using an apparatus having the structure shown in FIG. 1, coagulation filtration was performed using sewage (SS concentration: 95 mg / liter) flowing into a sewage terminal treatment facility as raw water. Table 1 shows the specifications of the upflow filter.

[0013]

[Table 1]

[0014] PAC (polyaluminum chloride) was added to sewage at 100 mg / liter, and magnetite magnetic particles (2000 gauss) having an average particle size of 2 µm were added at various addition rates. 1.5 mg / liter of anionic polyacrylamide, molecular weight: 15 million, trade name: Evacloth A153) was added,
The liquid was supplied to the filtration device in an upward flow. Table 2 shows the relationship between the magnetite addition rate and the critical upward flow rate (the condition where the filtration continuation time when the filtered water SS becomes 10 mg / liter or less and the filtration continuation time becomes 3 hours or more) under these conditions.

[0015]

[Table 2]

From the results shown in Table 2, it was confirmed that the upflow filtration device to which the magnetic particles of the present invention were added can set a solid-liquid separation speed about 10 times as high as that in the case where no magnetic particles were added. .

[0017]

According to the present invention, an extremely high solid-liquid separation speed can be set by flowing raw water to which a flocculant and magnetic particles have been added through a granular filter medium packed bed having a large porosity in an upward flow. Since the solid-liquid separator can be remarkably miniaturized, it is extremely useful when applied to this type of water treatment.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of a high-speed filtration / separation method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw water 2 Raw water supply pipe 3 Inorganic coagulant 4 Magnetic particle 5 Polymer coagulant 6 Coagulation tank 7 Coagulation treatment water 8 Filtration tank 9 Granular filter material packing layer 10 Net 11 Outflow pipe 12 Treated water 13 Sludge 14 Sludge discharge pipe 15 Valve 16 Magnetic particle recovery unit 17 Recovered magnetic particles 18 Sludge 19 Circulation pipe

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B01D 29/66 B01D 29/08 520B 29/94 530C 540A 29/38 510B 520A 29/42 520 F term (reference) 4D015 BA08 BA12 BA15 BA22 BA29 BB09 BB13 CA01 CA14 DA04 DA05 DA13 DA37 DB02 EA06 EA37 FA03 4D062 BA08 BA12 BA15 BA22 BA29 BB09 BB13 CA01 CA14 DA04 DA05 DA13 DA37 DB02 EA06 EA37 FA03

Claims (2)

[Claims] 1. A magnetic particle-containing floc is formed by adding magnetic particles and a flocculant to raw water, and then water is passed in an upward flow through a granular filter medium-filled layer having an initial porosity of 80% or more, thereby forming a magnetic particle-containing floc. Is filtered and separated in the granular filter medium packed bed. 2. A coagulation tank for coagulating by adding a coagulant and magnetic particles to raw water, forming a granular filter medium packed layer having an initial porosity of 80% or more inside the coagulation tank, and coagulating from the coagulation tank through an inlet pipe provided below. Flow treated water through the granular filter media packed bed as upward flow,
A filtration tank having a discharge pipe for draining treated water from the upper part and discharging sludge during washing, and introducing sludge from the discharge pipe during washing of the filtration tank, separating magnetic particles and sludge, and collecting magnetic particles. A high-speed filtration / separation device for suspension water, comprising: a recovery section;