JPS60814A - Formation of precoat layer for filtration apparatus and filtration method - Google Patents

Abstract

PURPOSE:To form a thick precoat layer of good quality by using a trace amt. of a high molecular flocculant together with pulverized coal(coke) to form a precoat layer for a filtration apparatus. CONSTITUTION:Water is charged into a water tank outside of a rotary drum, and pulverized coal(coke) is added to make a slurry, to which a small amt. of a high molecular flocculant is added. A thick precoat layer of good quality is formed on filter cloth lining the surface of the rotary drum by starting the suction and revolution of the rotary drum. The wire gauze with small meshes or a screen made by setting wedge wire are used other than the filter cloth in accordance with filtration apparatuses of different kinds. In either case, the precoat layer of good quality can be formed by this method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention describes a method for forming 1fli (preco), which is used as a p-bed when separating suspended substances in a liquid using a reduced-pressure (commonly known as vacuum) rotary filter. and the filtration method using it.
Separately, for clarification etc., diatomaceous earth, zeolite, lime powder, activated return powder, coke powder, etc. were often used as TP super-aids. That is, before complete filtration, the above-mentioned known filter aid is added to the stock solution containing suspended solids (hereinafter abbreviated as SS) to form a uniform slurry, and both the SS and the aid are separated. It was often used as an aid method.

Apart from that method, before filtration, the rotating drum is immersed in a slurry liquid in which diatomaceous earth, etc. is suspended in advance, or the slurry liquid is poured onto the outer surface of the drum to reduce the pressure inside the drum. A so-called pre-coat method is also known, in which a layer of diatomaceous earth or the like is left on the offshore surface made of a liquid-permeable porous material by suctioning water to form a pre-coat layer, and then the undiluted solution containing the original SS is filtered. ing.

This relates to the latter pre-coating method.

This pre-coat method (1) In the case of filtration of difficult-to-filter SS, sticky organic sludge is directly applied to the surface of the porous material from door to door.
In addition to preventing clogging of porous objects (e.g. furnace cloth, wire mesh, surfaces lined with wedge wires, etc.) that occur due to adhesion and which are difficult to recover from, When the surface of the pre-coat layer becomes clogged and the filtration speed decreases, the feature is that it can maintain a high filtration speed while scraping off the surface layer to a very small extent.
This pre-coating method is mainly used for rotary vacuum overloading, and diatomaceous earth is used industrially for floor desks as a pre-coating material.

However, there are still many issues that require major improvements, and the current situation is such that recent social demands for environmental conservation have increasingly forced us to resolve these issues.

That is, in order to remove a small amount of suspended matter (SS component),
61. due to the discharge of a large amount of diatoms containing it.
Ta. The stock solution that is applied to such a rotary vacuum filtration machine (general KSS components are often around 100 to 50 (In/L), but when this first solution is applied to a pre-cord furnace i1M machine, it contains waste materials. The diatom stage is the first few dozen SS ingredients...
The number of mosquitoes can be as high as 100 times (scenery).

If the contaminated SS components in the soil are inorganic compounds, there is relatively little problem in simply dumping them in a landfill, but organic compounds, especially food processing wastewater and extracts of crude drugs, Liquid, water and sewage customs clearance 4I [i] In the case of waste water treatment from facilities, the waste bulb algae will emit a foul odor over time and cannot be disposed of in a landfill, and TFC thick externally combustible diatomaceous earth should be used. Therefore, it was difficult to incinerate the waste.

In order to solve this problem, the inventors of the present invention have conducted many experiments in order to replace the non-flammable filter aid with a flammable filter aid. In place of diatomaceous earth, we tried using wood flour, fiber waste, etc., but these had many drawbacks in terms of price and availability.

SS uses fine coal (coke) powder as a filter aid.
Waste aids containing the following ingredients can be disposed of by self-combustion, which is expected to prevent the generation of bad odors and reduce disposal costs by reducing the amount of ashing.
80-120 yen/K) than fine coal (coke) powder (
It also has an economical advantage of being inexpensive (20 to 50 yen/K).

Prior to the present invention, the SS component (SS component
or coloring component) pulverized coal] A method is used in which these are simultaneously dehydrated and filtered as a mixed slurry. In this method, the SS component and fine powder (activated) carbon are suspended at the same time without forming preneat W4 on the surface of the porous body prior to filtration of the SS component. Since it comes into contact with the surface of the porous body, clogging of the surface of the door cloth is unavoidable, which has the drawback of gradually decreasing the filtration rate.

Therefore, after forming fine coal (or coke) scum (precoat layer) on the surface of the porous body in advance, the SS component is removed from door to door, and the surface is constantly scraped to create a new precoat surface, which is then filtered. is used in almost all (rotary) reduced pressure (vacuum) dehydrators.

However, surprisingly, although a thick precoat layer can be easily formed with diatomaceous earth slurry using the method described above, even if we try using fine coal (coke) powder with the same particle size, fine coal (coke) ) The powder layer fell apart and was thicker than it could have been, so a good quality precoat layer was not formed. It was also observed that the pulverized coal that floated on the surface was too loose and lacked affinity with water.

Due to their unique shape and properties, polymorphous soil particles interlock with each other to form a stable layer, whereas in pulverized coal (coke), the particles themselves are smooth and the particles tend to stick to each other or collide with each other. There was no formation of a thick layer at all, indicating that it was difficult to form a thick layer.

In order to form a stable and thick pre-coat layer using fine coal (coke) powder, the inventor of the present invention repeatedly conducted intensive tests and found that the same operation was performed with the addition of a small amount of organic polymer flocculant. This is a newly discovered fact that allows a high-quality precoat layer to be formed on the drum surface.

That is, water is put into the aqueous phase outside the rotating drum, pulverized coal (coke) is added, it is made into a suspended slurry, a small amount of polymer flocculant is added to this, and when the rotating drum starts to suck and rotate, it produces extremely high quality A thick layer of fretstone is formed on the furnace cloth stretched over the surface of the rotating drum. Depending on the model 1,
In addition to furnace cloth, fine wire mesh or wedge wires are also used as the liquid-permeable porous material stretched over the drum surface; It is possible to tighten it.

In this case, when coal (coke) powder is sucked onto the surface of the revolving door, it becomes somewhat sticky due to the action of the polymer flocculant, and the polymer flocculation effect also works together to cause the particles to stick to each other. It is thought that a high-quality pre-coat layer was formed through light adhesion, but the present invention is based on the combination of coal (coke) powder and a polymer flocculant, regardless of the elimination of the mechanism of action and the formation of a high-quality precoat layer. This is based on the fact that a thick, high-quality precoat layer is formed.

Using the pre-coat layer formed by the Kineri J method, it is possible to apply 44 liters of water to food products, filtration of r water in which minute pieces of meat are suspended, wastewater filtration in livestock human waste processing plants, and filtration of wastewater in manufacturing plants. When the suspension in the extraction waste liquid was subjected to f1 separation, very good results were obtained, and it was confirmed that the precoat layer was sufficiently stable for practical use.

Any commercially available coal (coke) grains can be used here, but if the grain size is too large, scrape off the wire and fried layer with a scraper (also called a cutter) to create a new surface. It creates unevenness when it comes out.

In addition, filtration accuracy also deteriorates.

On the other hand, if it is too small, there will be a drawback that the liquid flow resistance will increase and the filtration rate will decrease, and the handling of the powdered coal itself will be dangerous, so it is preferably about 30 to 200 microns. The type of charcoal may be any ordinary coal powder, anthracite powder, coal coke, or oil coke powder.

Since coal powder and coke powder can be used approximately equivalently, they can be mixed and used in any ratio.

The polymer flocculant used here and the commercially available flocculants for water treatment can all be used, although there are some differences in the appropriate addition of Itk, but especially anionic and nonionic flocculants are used in small amounts. Highly effective.

There are some differences depending on the frosting strain, charcoal type, and particle size, but the effect appears at a few to several tens of ppm.

In the second order of adding fine coal (coke) powder and polymer flocculant to water, whichever comes first, pre-coke) 1tj
can be formed, but with the formation of a better quality precoat layer,
In order to reduce the amount of flocculant used, the most desirable method is to add coal (coke) powder first and then add polymer flocculant later.The next best method is to add coal (coke) powder and polymer flocculant later. There is a method of adding both at the same time.

As mentioned above, when using the above pre-coated layer tube, good p-filtration performance can be obtained, but the filtration residue (cake) obtained by scraping with a cutter etc. and discharging it contains some moisture. However, once ignited, it can be easily self-combusted, incinerated, turned into ash, and dumped, with or without some auxiliary combustion such as heavy oil, and is unlikely to become a source of foul odors. do not have.

Economically, it costs about 2 times less than the conventionally most widely used material for forming the precoat, and it is extremely advantageous considering the total energy recovery obtained by burning the cake. It is.

Recently, a method of mixing coal powder as a filter aid into the slurry and filtering it when dehydrating and filtering biologically treated sludge using a filter press or a Peltogelles filter has been proposed, and after many improvements, it is finally approaching practical use. However, there are no known examples of coal powder being used to pre-clean the rotary drum type vacuum filtration machine that is the target of the misfire.

In the research conducted by the present inventor, it seems that it was difficult to form a good thick pre-coat layer using only coal powder, and it was found that it was difficult to form a good thick pre-coat layer using only coal powder. It was also confirmed that there have been no reported cases of using powdered glycerol.

The present inventor was able to solve this problem by using a small amount of a sieve molecular flocculant, which is easily available in Ichiko, together with pulverized coal (coke).

When the dehydrated cake obtained after filtration is combusted by the method 1, the SSS component contains mineral sulfur negative content, for example, some contain axoamino acids, and the sulfur contained in the pierced coal. In order to suppress the generation of sulfur dioxide gas due to the combustion of carbon dioxide, a two-component system consisting of [microcoke powder] and [polymer flocculant] is added to a small amount of [lime powder], such as calcium carbonate and hydroxide. Even if calcium powder is added as a third component in a small amount, for example, not exceeding 10% (by weight) of coal, there will be no problem in precoat formation and E performance.

The lime component reacts with the sulfur dioxide gas generated during the combustion of the axle compound, making it ineffective in trapping it. However, if too large a quantity is used, it will not only impair the combustibility of the waste cake but also increase the amount of ash to be discharged9. coal(
It is sufficient to add 10% or less to the coke powder.

The present invention will be explained below with reference to Examples.

Example I 470p of organic matter was found in the wastewater from a fish processing factory in S City.
Most of them were SS components having a size of 0.5 to 4 microns.

The above waste liquid was filtered through a continuous vacuum rotary dehydration filter (Ishigaki Kiko I).
A filtration test was conducted using CF type.

Fill the liquid tank outside the drum with water, and add 5% commercially available coal coke (brand unknown, particle size 5o~200 microns) into the tank.
(weight), make a pulverized coal slurry, and add a polymer flocculant (Toagosei Aronfloc 101) to it at a concentration of 2.5 ppm based on the amount of water.
The rotating p bodies were rotated almost simultaneously. Although some of the coal powder had floated to the surface before adding the polymer, a good-quality slurry liquid was obtained after the addition.

Once the water and fine coal (coke) powder (containing flocculant) were suctioned, the coal (coke) powder and flocculant were added to the raw solution tank again, and suction, filtration, and layering were continued.

The coal (coke) powder precoat layer gradually increases in thickness,
It reached a thickness of about 50 horses.

At the time when this precoat layer was formed, the above-mentioned fish meat processing wastewater was started to be supplied to the stock solution tank. The surface of the pre-coated layer line is covered with fish meat, and the cutter cuts off only the surface layer, about 1 cod per rotation, rotating slowly, and the pre-coated layer becomes 1C.
A good filtration rate could be maintained up to a thickness of III.

The average SS component in the filtrate filtered by the above method is 121
! It had decreased to 'I/II.

The coal powder containing sludge obtained by this method could be easily molded into a lump of about 3 diameters, and then burned and ashed in a furnace. Due to the high temperature combustion, the flue gas had almost no odor, and the amount of ash was very small.

Reference Example 1 During the precoat forming operation according to the procedure of the above example, especially when the addition of a polymer flocculant is omitted, some of the ore back powder floats to the surface, making it difficult to obtain a uniform slurry. A layer of coal only a few millimeters thick was formed, and the layer was so fragile that it could easily be completely peeled off from the bottom with a cutter.

Reference Example 2 When the above-mentioned waste liquid from a fish processing factory is subjected to p-filtration using a rotating drum covered only with p-cloth without pre-coating, the furnace cloth becomes almost clogged in about 30 minutes. Almost no filtrate was discharged.

Example 2 Using the same overfill tank used in Example 1, water was filled in the stock solution tank, and fine coal (coke) powder was added in an amount equivalent to about 596 (weight f!:), and 596 (weight f!:) was added to the coal powder ) was also mixed together with the calcium carbonate powder.

Claims (4)

[Claims] (1) The slurry obtained by adding all of the [fine coal powder and/or fine coke powder] and [polymer flocculant] is suctioned and filtered using a liquid-permeable porous body, and the slurry is poured onto the porous body. A method of forming a precoat layer for vacuum filtration on (2) In the method for forming a precoat layer shown in (1) above, [lime powder] is added as a third component to [microcoal powder or/and microcoke powder] and [polymer flocculant]. The slurry obtained by adding 205'1lf (weight) to the powder in a range not exceeding 205'1lf (weight) is suctioned and filtered using a liquid-permeable porous body, and precoated NI for vacuum filtration is applied onto the porous body. How to form (3) A method for forming a precoat layer characterized in that the fine coal (coke) powder used in the method shown in (2) above has a particle size of 30 to 300 microns. (4) A filtration method characterized by forming Grecode Fmt in advance by the method shown in Ill, (2), and (3) above, and then filtering and separating the entire stock solution containing suspended components.