KR20120021241A - Dewatering promoter for sludge and method and device for dewatering sludge - Google Patents

Abstract

PURPOSE: An auxiliary agent for dehydrating sludge and a method and an apparatus for dehydrating the sludge are provided to prevent the clogging phenomenon of filtering fabric by easily separating dehydrated cakes from the filtering fabric in case of compressive dehydration. CONSTITUTION: An auxiliary agent for dehydrating sludge is composed of a plurality of fiber. 5 to 20 concave parts are longitudinally expanded along the outer circumference of the fiber. Lines are longitudinally expanded at the concave parts. The lines function as moisture transferring paths through which moisture is transferred based on a capillary action in case of the contact of sludge. The moisture content of the auxiliary agent is 30-80 weight%. The length and the fiber diameter of the auxiliary agent are 1 to 50mm and 1 to 100um, respectively.

Description

Dehydration aid for sludge and method and device for dewatering sludge {DEWATERING PROMOTER FOR SLUDGE AND METHOD AND DEVICE FOR DEWATERING SLUDGE}

The present invention relates to a dehydration aid for use in dewatering sludge generated from sewage treatment facilities, manure treatment facilities, and other wastewater treatment facilities, and a method and apparatus for dewatering sludge using the dehydration aid.

Conventionally, the process which adds an organic polymer flocculant to the sludge (henceforth "slow") which generate | occur | produces from a sewage treatment facility, a manure processing facility, and other wastewater treatment facilities is performed for mechanical dehydration. However, since sludge has become dehydrated recently due to changes in lifestyle, etc., it is difficult to reduce the water content of sludge even when mechanical dehydration is performed. In particular, dehydration of oxidized ditch treated sludge is very poor compared to mixed raw sludge, surplus sludge of activated sludge, digested sludge and the like. This is considered to be because the aeration time in the oxidizing sphere method is very long, so that nitriding and denitrification proceeds, the fiber fraction in the sludge is considerably decomposed, and the fiber fraction in the sludge which becomes the nucleus of aggregation is reduced. Furthermore, in the case of using a pressurized dehydrator such as a belt press dehydrator or a filter press dehydrator, the peelability of the dehydration cake from the filter cloth is poor and the filter cloth is clogged, which causes poor filtration and prevents stable dehydration. There is also a problem that the cleaning of the filter cloth takes time.

In the manure treatment facility, since most of the contaminants are removed from the sludge by the screen provided at the front end of the biological treatment, the generated sludge contains less fiber powder, which reduces the moisture content of the sludge. It is difficult.

In addition, from the viewpoint of recycling waste, composting of sludge is being promoted. In the case of the composting process, the water content of the target sludge needs to be 40 to 60%. In addition, in composting, the drug used in the dehydration treatment or the like needs to be biodegradable (decomposable to microorganisms).

As a means of reducing the water content of sludge, the method of adding a polymer flocculent and dehydrating after mixing a sludge fibrous substance is proposed. For example, the method of dehydrating after adding synthetic fiber and a flocculant to organic sludge (Japanese Unexamined-Japanese-Patent No. 2002-219500) etc. is proposed. By this method, compared with the method of adding the conventional tissue cutting material, the dehydration cake with a low water content is obtained even with a small addition amount.

By the method of mixing a sludge synthetic fiber, the some cake moisture content can be reduced. However, according to a study by the present inventors, when the wettability of the synthetic fiber to the sludge is insufficient, when the synthetic fiber is introduced into a sludge storage tank or the like which is not equipped with a device capable of sufficiently stirring the entire inside of the tank. Opening in sludge was difficult, and it turned out that synthetic fiber cannot be mixed uniformly in sludge. In addition, even if the synthetic fibers could be mixed uniformly in the sludge, it was found that stable dehydration treatment cannot be performed because the synthetic fibers are separated from the sludge when pressed in the dehydrator, and cannot contribute to dehydration. In addition, some fibrous substances are difficult to decompose into microorganisms, and may not be suitable for composting.

As a result of the investigation by the present inventors, the known synthetic fibers have no clear reason, but depending on the properties of the sludge, the effect of reducing the cake moisture content may be hardly obtained. It turns out that it is not a fundamental solution alone.

Techniques for lowering the water content of the dehydrated cake using synthetic fibers have been studied as described above. However, most of the prior art attempts to lower the water content by adjusting the material, thickness and length of synthetic fibers. However, as a result of the investigation by the present inventors, it was found that the water content of the dehydrated cake cannot be sufficiently lowered even by mechanically dehydrating the hardly dehydrated sludge only by adjusting the material, thickness and length of the synthetic fiber.

Japanese Unexamined Patent Publication No. 2002-219500

An object of the present invention is to solve the drawbacks of the known technique and to provide a dehydration aid capable of obtaining a low moisture content dehydrated cake from a poorly dehydrated sludge, and a method and apparatus for dewatering sludge using the dehydration aid. .

In order to solve the above problems, the present inventors earnestly studied, and found that the cross-sectional shape of the fiber influences the dehydration of sludge. The present invention is a novel sludge dewatering method made on the basis of such knowledge.

The present inventors dehydrate water for sludge having a fibrous material having 5 to 20 uneven parts at the outer periphery of the cross section of short fibers, and having continuous streaks continuously in the fiber axis direction of the concave portion. When used as an adjuvant, it was found that the dehydration rate of sludge improves. 5-20 uneven | corrugated parts exist in the outer peripheral part in the cross section of each fiber which comprises the sludge dehydration adjuvant. In the recess, there are streaks, i.e. lines, continuous in the fiber axis direction, that is, in the longitudinal direction of the fiber.

Therefore, according to the present invention, a plurality of fibers are collected and have 5 to 20 recesses extending along the longitudinal direction of the fibers on the outer circumferential surface of each fiber, and the recesses have a capillary action when sludge comes into contact with the recesses. There is provided a dewatering aid for sludge, wherein a line acting as a water transport path for transporting water extends along the length direction of the fiber.

In the sludge dewatering aid, the fiber is preferably a regenerated cellulose fiber. It is preferable that the said fiber is not in a dry state but has a moisture content in the range of 30-80 mass%. Moreover, it is preferable that the length of a fiber is 1 mm-50 mm, and a fiber diameter is 1 micrometer-100 micrometers.

According to this invention, the sludge dewatering method using the sludge dehydration adjuvant is provided. In the method for dewatering sludge of the present invention, after the organic sludge is added and mixed with the sludge dehydration adjuvant, a polymer flocculant is added to agglomerate the organic sludge, followed by mechanical dehydration. A method of aggregating organic sludge by adding a dehydration aid-containing polymer flocculant liquid formed by mixing an auxiliary agent and a polymer flocculant, and then mechanically dehydrating the organic sludge, or simultaneously adding the dehydration aid for sludge and a polymer flocculant to the organic sludge Any of the aspect which aggregates and mechanically dehydrates is included.

Moreover, according to this invention, the sludge dewatering apparatus which mechanically dehydrates the organic sludge using the said sludge dewatering adjuvant is provided. The sludge dewatering apparatus of the present invention includes a sludge storage tank, a flocculation tank, a mechanical dehydrator, a dehydration aid supply for supplying the sludge dehydration aid to organic sludge, and a polymer flocculant dissolving device for dissolving the polymer flocculant supplied to the flocculation tank. do. The dehydration aid supply device is connected to at least one of the sludge storage tank, the flocculation tank, the mechanical dehydrator, or the polymer flocculant dissolving device via a pipe. The said polymer coagulant dissolving apparatus is connected to the coagulation tank through piping.

In the sludge dewatering apparatus of the present invention, a sludge concentration tank may be provided in front of the sludge storage tank. The sludge concentration tank may be connected to the dehydration aid feeder. Moreover, in the sludge dewatering apparatus of this invention, the slit saver provided with a group of elliptical plates which rotates between the said flocculation tank and the said mechanical dehydrator, or the filtration concentrate, such as a screen inclined downward from the exit of the flocculation tank, etc. You may install a part. In the sludge dewatering apparatus of the present invention, it is preferable to use a screw press dehydrator as the mechanical dehydrator.

According to the present invention, by using a sludge dewatering aid composed of fibers having a unique cross-sectional shape, the moisture content of the dehydrated cake is satisfactorily lowered with a small amount of addition compared to the conventional method for adding synthetic fibers even in poorly dehydrated sludge. You can. In addition, by using the sludge dewatering aid of the present invention, in the case of pressurized dehydration, the dewatering cake can be easily peeled from the filter cloth, and clogging of the filter cloth can be prevented.

1 is a flow configuration diagram showing an example of the sludge dewatering apparatus of the present invention;
2 is a flow configuration diagram showing another example of the sludge dewatering apparatus of the present invention;
3 is a flow diagram showing another example of the sludge dewatering device of the present invention;
4 is a cross-sectional perspective view of fibers constituting dehydration aids A, B, E, and G (Examples);
5 is a cross-sectional perspective view of the fibers constituting the dehydration aid C, D (Example);
6 is a sectional perspective view of a fiber constituting the dehydration aid F (Example);
7 is a sectional perspective view of the fibers constituting the dehydration aid H (Example),
8 is a sectional perspective view of a fiber constituting the dehydration aid I (comparative example),
9 is a cross-sectional perspective view of fibers constituting dehydration aids J and K (commercially available products);
10 is a cross-sectional view of the fibers constituting the dehydration aid showing the fiber diameter,
It is sectional drawing of the fiber which comprises the dehydration adjuvant which shows the depth to the vertex of the deepest part of the recessed part which forms a line.

The sludge dewatering aid of the present invention is formed by a plurality of fibers gathered and has 5 to 20 recesses extending along the longitudinal direction of the fibers on the outer circumferential surface of each fiber, and when the sludge contacts the recesses. Since the line acting as a water transfer path for transferring moisture by capillary action extends along the length direction of the fiber, excellent water absorption and hydrophobicity are obtained.

Background Art Conventionally, in the field of medical care such as underwear and sportswear, it is intended to eliminate unpleasant feelings such as stickiness due to wetness at the time of sweating and impart high absorbency to fibers. Since moisture is absorbed from the surface of the fiber, in order to increase the absorption rate, the surface area may be increased to adsorb a large amount of moisture. The more uneven the surface is, the larger the surface area becomes, and the concave portion of the surface can hold moisture until the water penetrates into the fiber. For this reason, in the medical field, such as underwear and sportswear, Y-type, X-type, or T-shaped fiber of cross-sectional shape is said to be preferable. However, when the present inventors examined and cut | disconnected Y-type, X-type, or T-shaped fiber and used it for dehydration of sludge, although some reduction of cake moisture content is recognized, it is difficult to produce the same thing as an oxidized sphere treated sludge. It was found that the water content of the dehydrated cake did not decrease to the extent that the dehydrated sludge could be satisfied. Although the reason is not clear, since the opening part of a concave part becomes wide in a cross-section, it is long, and the opening capillary is blocked by small sludge particle | grains, and it becomes impossible to serve as a capillary furnace, and it is high crimping at the time of machine dehydration. It is presumed that the cause is that the pressure portion is not tolerated and the crack part is destroyed.

The fiber used for the dehydration adjuvant of this invention has 5 or more and 20 or less, Preferably it is 10 or less recesses extended on the outer peripheral surface along the longitudinal direction of a fiber. If the concave portion of the outer circumferential surface is too large, the opening area is rather narrowed, so that the function as a dehydration aid is not available, making it difficult to manufacture industrially and cost-effectively. Moreover, the dehydration adjuvant of this invention can also provide a recessed part in the outer peripheral surface of the fiber of the said Y-type, X-type, or T-shaped cross-sectional shape. However, such fibers have long lengths in their cross-sections and need attention, because the lengths of the fibers are likely to break due to the pressing pressure applied during mechanical dehydration.

The fiber used for a dehydration adjuvant does not need to be a fiber which has the same number of recessed parts, You may mix the fiber which has five or more recessed parts. Moreover, you may mix the fiber which has less than five recessed parts in the range which does not impair dehydration.

Next, the line extending in a fiber longitudinal direction is demonstrated. The line of the concave portion extending along the longitudinal direction of the fiber acts as a water transfer path for transferring moisture by capillary action when sludge contacts the dehydrating aid of the present invention. Due to the capillary action, the dehydration aid of the present invention significantly improves the absorption performance as compared with the dehydration aid using a conventional fibrous substance. The reason is not yet clear, but the contact surface area of the sludge and the dehydration aid is increased, and the water is sucked out of the sludge by capillary action, and the internal structure of the dehydration aid is suitable for the passage of water molecules. I think it is because.

From the viewpoint of workability at the time of addition, mixing, and dehydration of sludge, the length of each fiber constituting the dehydration aid is 1 to 50 mm, preferably 3 to 20 mm, and the fiber diameter is 1 μm to 100 μm. Preferably, it is about 5 micrometers-about 50 micrometers. Here, as shown in FIG. 10, "fiber diameter" means the longest distance which connects the vertices of a convex part regardless of whether a cross-sectional shape is symmetrical or asymmetrical. Moreover, as shown in FIG. 11, it is preferable that the vertical distance (D1-D3 in the case of FIG. 11) to the tangent which connects the vertex of an adjacent convex part, and the vertex of the deepest part of a recessed part is 0.1-5 micrometers.

Moreover, it is preferable that specific gravity in a dry state is 1.4 or more in a dehydration adjuvant. When the specific gravity is less than 1.4, when treating a high concentration of sludge or when agitation of a sludge storage tank is slow, the contact of a dehydration adjuvant and sludge becomes worse, and time for mixing uniformly becomes long.

It is preferable that the moisture content is 30 to 80 weight%, and, as for the dehydration adjuvant of this invention, it is more preferable to exist in the range of 40 to 70 weight%. If the water content is 30% by weight or less, wettability with sludge is poor, and the dehydration aid is in a state in which the dehydration aid is unevenly dispersed. In addition, when mixing in the polymer coagulant dissolving tank mentioned later, a polymer coagulant may melt | dissolve completely and a solution may become high viscosity, and it is difficult to disperse | distribute a dehydration adjuvant uniformly in the whole dissolution tank. On the other hand, when the moisture content exceeds 80% by weight, the moisture of the glass not impregnated with the fiber increases, so that the quantitative supply is difficult when mechanically supplied by the feeder or the like. Moreover, since the ratio of the fiber fraction of the dehydrated sludge distributed in sludge becomes small, it is economically disadvantageous.

As a method of adjusting the moisture of a dehydration adjuvant, the following method can be used preferably. When using the fiber manufactured by the dry spinning method, water is sprayed on the fiber after manufacture by spraying, water content is adjusted after adjusting water content, or water is sprayed after cutting. In the case of using the fiber produced by the wet spinning method, the solvent may be substituted, pressed with a roller or the like after washing, or dried to remove moisture to cut to a predetermined length, or dried after cutting.

As a fiber which comprises the dehydration adjuvant of this invention, a regenerated cellulose fiber is especially preferable. Examples of the regenerated cellulose fibers include regenerated artificial fibers such as viscose rayon fibers made of cellulose and cupraray fibers, semisynthetic regenerated fibers such as cellulose diacetate fibers and cellulose triacetate fibers. Viscose rayon fiber is especially preferable at the point which forms a convex part and the recessed part in which a vertex extends in a line shape in a fiber, or is easy to adjust a water content. The regenerated cellulose fibers have biodegradability and decompose and disappear in the soil, which is suitable for reusing dehydrated cakes for fertilizers and the like. Even if it has biodegradability, cotton, flax, wool, and the like do not have a line extending in the fiber length direction, that is, a water transfer path, and therefore, an effect as a dehydration aid cannot be expected.

In the method of the present invention, the amount of the dehydration aid added to the sludge varies depending on the concentration of each sludge. Generally, it is preferable to set SS (floating substance concentration) in sludge to 100 and add 0.1-20 weight%, Preferably 1-10 weight%. When the addition amount of the dehydration aid is less than 0.1% by weight, the effects of the present invention are not obtained. On the other hand, when it exceeds 20 weight%, it becomes difficult to mix a dehydration adjuvant uniformly in sludge, and also it is economically disadvantageous.

Dewatering treatment of sludge which mixed the dehydration adjuvant of this invention can be performed using a normal pressurized dehydrator, a vacuum dehydrator, a belt press dehydrator, a centrifugal dehydrator, and a screw press dehydrator. In particular, in recent years, screw press dehydrators have been employed as dehydrators for sparse dewatering sludge treatment in medium scale sewage treatment plants. When the sludge is dewatered by a screw press dehydrator, it is preferable to add a dehydration aid having a length of 3 to 20 mm to the sludge, and 1 to 10% by weight in terms of dryness with SS in the sludge as 100. It is preferable to add in the range. On the other hand, even when the dehydration treatment is performed using a belt press dehydrator or a centrifugal dehydrator, a dehydration aid having a length of 3 to 20 mm can be preferably used, and the SS in the sludge is 100 to be added in the range of 1 to 10% by weight. It is preferable.

It is preferable to add the dehydration adjuvant of this invention to a sludge storage tank, and to mix with sludge. In the absence of a sludge storage tank, a dehydration aid may be added to the sludge in any pipe from the condenser to the sludge dehydrator, or a dehydration aid may be added to the sludge before the sludge concentration step.

When adding a dehydration adjuvant to the sludge of a sludge concentration tank and a sludge storage tank, it can carry out collectively so that it may become the range of the said addition amount. In addition, when it adds to sludge in piping, since a sludge inflow and drawing may be carried out always or intermittently, you may add a dehydration adjuvant suitably according to the inflow amount and draw amount of sludge. In addition, when adding in front of a dehydrator, what is necessary is just to add a dehydration adjuvant so that it may become the said addition amount with respect to the sludge flow volume supplied to a dehydrator. The addition of the dehydration aid may be either before or after the addition of the flocculant. However, from the point of uniformly mixing the dehydration aid in sludge, it is more preferable to add it before the addition of the flocculant. After adding a flocculant, when adding a dehydration adjuvant to sludge, either the sludge in a flocculation tank, the sludge in the granulation thickening tank provided downstream of the flocculation tank, and the sludge from the flocculation tank after coagulation filtration. You may add to sludge. Recently, a screw press dehydrator having a filtration concentration section has been developed. In the case of this type of dehydrator, after the filtration concentration, the dehydration aid may be added to the portion where the flocculated sludge is supplied to the dehydrator main body, and uniform mixing of the sludge and the dehydration aid is possible. A dehydration adjuvant may be added to sludge as a fibrous form (that is, solid substance), and may be added to sludge after adding water to make slurry. In any case, quantitative addition is possible using the supply apparatus which was in shape.

In addition, you may add a dehydration adjuvant simultaneously with a polymeric flocculant. Specifically, a predetermined amount of the dehydration aid may be added to and mixed with the polymer coagulant dissolving tank during or after dissolving the polymer coagulant. The dehydration aid uniformly dispersed together with the polymer flocculant in the polymer flocculant dissolution tank is introduced into the flocculation floc while the sludge forms the flocculation floc in the flocculation tank.

The flow block diagram of the apparatus used for the dewatering method of the sludge of this invention is shown in FIGS.

1 is an example of using the belt press dehydrator 4 as a mechanical dehydrator. The sludge concentrated in the sludge concentration tank 1 is sent to the sludge storage tank 2 at the bottom of the sludge concentration tank 1, and stored for a predetermined time. Thereafter, the sludge is sent from the sludge storage tank 2 to the coagulation tank 3. In the coagulation tank 3, a polymer coagulant is added from the polymer coagulant dissolving tank 6 to coagulate sludge to form a flocculation floc. Next, the flocculation floc is sent to the dehydrator 4 and dewatered to form a dehydrated cake. A pipe is connected from the dehydration aid supply 5 to one or more of the sludge concentration tank 1, the sludge storage tank 2, the flocculation tank 3, and the polymer flocculant dissolution tank 6 so that the dehydration aid can be added. What is necessary is just to select a some tank and piping separately or simultaneously in the place which adds a dehydration adjuvant to sludge according to a process situation. When the dehydration aid is added to the flocculation floc, the contact between the individual sludge and the dehydration aid decreases. Therefore, it is preferable to add the dehydration aid to the sludge before adding the polymer flocculant or simultaneously with adding the polymer flocculant. For this reason, it is especially preferable to add the dehydration adjuvant to the sludge concentration tank 1 or the polymer flocculant dissolution tank 6.

2 shows an example in which a screw press dehydrator 7 is used as a mechanical dehydrator and two tank type coagulation tanks 3-1 and 3-2 are used as a coagulation tank. Addition of a dehydration adjuvant should just be the same as embodiment shown in FIG. In the case of this embodiment, after adding a dehydration adjuvant to the 1st flocculation tank 3-1, a polymeric flocculant is added to the 2nd flocculation tank 3-2, and a sludge and a dehydration adjuvant are introduced together in a flocculation floc. It is particularly preferable to.

Fig. 3 shows a two-tank flocculation tank 3-1 as a flocculation tank using a screw press dehydrator 7 having a filtration concentration section 8 provided at the rear end of the flocculation tank 3 as a mechanical dehydrator. , 3-2). In the filtration concentration section 8, the water contained in the sludge agglomerated in the flocculation tank 3 is roughly dehydrated to concentrate the flocculation floc including the dehydration aid and sludge. The filtration concentrator 8 is a separate device disposed between the coagulation tank and the dehydrator, for example, a slit saver having a rotating group of elliptic plates, or a screen inclined downward from the outlet of the coagulation tank, or a coagulation tank. It may be a granulation concentration tank having a slit filter cylinder provided therein. In embodiment shown in FIG. 3, addition of a dehydration adjuvant should just be the same as embodiment shown in FIG.

As the polymer coagulant, a cationic polymer coagulant or an amphoteric polymer coagulant, an anionic polymer coagulant, or a nonionic polymer coagulant may be used. The cationic polymer coagulant has a cationic monomer unit as an essential component, and there are a copolymer of a cationic monomer and a copolymer of a cationic monomer and a nonionic monomer. Examples of the cationic monomers include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate or their neutralized salts and quaternary salts. In addition, cationic polymer coagulants containing amidine units in the molecule can also be used. As a nonionic monomer, acrylamide, methacrylamide, methacrylonitrile, vinyl acetate, etc. are mentioned.

An amphoteric polymer flocculant is a copolymer of a cationic monomeric unit, an anionic monomeric unit, and a nonionic monomeric unit. As the anionic monomer, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, and such alkali metals and alkaline earth metals Metal salts or ammonium salts, such as these, are mentioned.

Examples of the anionic polymer coagulant include polyacrylamide partial hydrolyzates, copolymers of anionic monomers, and copolymers of nonionic monomers such as anionic monomers and acrylamides. Examples of the anionic monomers include those mentioned above, and these anionic monomers may be used alone or in combination of two or more thereof. As said nonionic monomer, said thing is mentioned, Such a nonionic monomer may be used independently, and may be used in combination of 2 or more type. Preferable examples of the copolymer include acrylamide acrylate copolymers and acrylamide 2-acrylamide-2-methylpropanesulfonic acid copolymers.

A nonionic polymer coagulant is a polymer or copolymer of the said nonionic monomer, Preferably it is polyacrylamide.

As the shape of the polymer flocculant, both powder and emulsion shapes can be used.

Moreover, as a method of adding a polymer flocculant, a two-part method of adding an anionic polymer flocculant after adding a sludge cationic polymer flocculant can also be applied.

Moreover, the method of adding a polymeric flocculant after adding an inorganic coagulant or an organic polymer coagulant is also applicable. As the inorganic coagulant, sulfuric acid bands, polyaluminum chloride (PAC), polyferric sulfate (polyiron), ferric chloride or mixtures thereof commonly used in sludge treatment techniques can be used. Examples of the organic polymer coagulant include condensed polyamines, dicyandiamide formalin condensates, polyethyleneimines, polyvinyl tolazolines, polyvinylpyridine, diallylamine salts, sulfur dioxide copolymers, polydimethyldiallylammonium salts and polydimethyldiallylammonium salts. A sulfur dioxide copolymer, a polydimethyldiallylammonium salt, an acrylamide copolymer, a polydimethyldiallylammonium salt, a diallylamine hydrochloride derivative copolymer, an allylamine salt polymer, etc. can be used. Specific examples of the condensed polyamine include condensates of alkylenedichloride and alkylene polyamines, condensates of aniline and formalin, condensates of alkylenediamine and epicrohydrin, and condensates of ammonia and epicrohydrin. have. Examples of the alkylenediamine condensed with epichlorohydrin include dimethylamine, diethylamine, methylpropylamine, methylbutylamine, dibutylamine, and the like.

In the sludge dewatering method of the present invention, an antifoaming agent or a deodorant generally used in sludge treatment techniques may be impregnated in advance in a dehydration aid. Moreover, you may mix the pulverized material of another natural fiber, etc. with a dehydration adjuvant.

The sludge to be dehydrated in the sludge dewatering method of the present invention does not matter what kind of sludge occurs in the active sludge treatment step in general drainage treatment, manure treatment and sewage treatment. In particular, the effect of the present invention is best exhibited in the dewatering treatment of sludge that is poor in cohesiveness and hardly deteriorates the water content of dehydrated sludge, such as excess sludge generated from the oxidative sphere method, sludge digested sludge, and sludge generated from a manure treatment facility. Can be.

[Example]

Hereinafter, an Example demonstrates this invention in detail.

[Production of Dehydration Aids]

The dehydration adjuvant used in the Example was manufactured by the following method.

<Dehydration Aid A>

In a spinning bath containing sulfuric acid, soda sulfate, and zinc sulfate, a viscose solution (spinning stock solution) containing 8.1 wt% of cellulose was continuously passed through a spinneret having a circular cross section. Extruded and spun to cellulose fibers. Next, the cellulose fibers were introduced into a stretch-regeneration bath containing sulfuric acid, stretched and regenerated to obtain regenerated cellulose yarns. The regenerated cellulose thread was sandwiched with a roller to remove water and adjusted to a water content of 58%, and then cut into lengths of 10 mm.

<Dehydration Aid B>

Except that the regenerated cellulose yarn was cut | disconnected to length 1mm, it processed similarly to dehydration adjuvant A.

<Dehydration aid C>

Except for spinning through a spinneret having a Y-shaped cross section, it was treated in the same manner as the dehydration aid A to obtain a regenerated cellulose yarn. The regenerated cellulose yarn was dried for 2 hours at a temperature of 105 ° C. with a dryer, cut into lengths of 5 mm, and sprayed with water to adjust the water content to 48%.

<Dehydration Aid D>

Except that the regenerated cellulose yarn was cut | disconnected to length 15mm, it processed similarly to dehydration adjuvant C.

<Dehydration aid E>

Except that the regenerated cellulose thread was cut | disconnected to length 38mm, it processed similarly to dehydration adjuvant A.

<Dehydration aid F>

The regenerated cellulose yarn was obtained using the spinning stock solution which melt | dissolved the cellulose triacetate flake in the methylene chloride / methanol mixed solvent. The obtained regenerated cellulose yarn was cut | disconnected to length 5mm.

<Dehydration aid G>

Instead of pressing with a roller, the regenerated cellulose yarn was dried at a temperature of 105 ° C. for 2 hours in a dryer, and then treated in the same manner as in the dehydration aid A, except that it was cut to a length of 5 mm.

<Dehydration aid H>

The regenerated cellulose yarn obtained by continuous spinning through a spinneret having an elliptic cross section was dried for 2 hours at a temperature of 105 ° C. with a dryer, then cut into a length of 10 mm, and dehydrated except that the water content was adjusted to 54% by spraying water. Treatment was carried out in the same manner as A.

Dehydration Supplement I

Polyethylene glycol was added to the spinning stock solution of the dehydration aid F, and was treated in the same manner as the dehydration aid A, except that the regenerated cellulose yarn obtained by continuously extruding and spinning through a spinneret having a Y-shaped cross section was cut to a length of 5 mm. .

<Dehydration aid J>

Commercial cupra rayon filaments were cut to a length of 10 mm.

<Dehydration aid K>

Except for using the spinning stock solution prepared by adding polyethylene glycol and sodium carbonate to a viscose solution containing 8.1 wt% of cellulose, the regenerated cellulose yarn was obtained in the same manner as in the dehydration aid A. The regenerated cellulose yarn was dried at a temperature of 105 ° C. for 2 hours in a dryer, cut into 10 mm in length, and sprayed with water to adjust the water content to 43%.

The moisture content of the dehydration adjuvant measured the weight (a) g of the dehydration adjuvant as prepared, and weighed the weight (b) g of the dehydration adjuvant after dehydration by drying the dehydration adjuvant at 105 ° C for 4 hours, (ab) It calculated by the formula of / a × 100 (%).

The number of concave portions of the fibers and the presence or absence of extending lines were visually counted by microscopic observation.

Table 1 shows the properties of the dehydration aid used in this example.

The perspective view containing the fiber cross section of dehydration adjuvant A-K is shown to FIGS.

4 is a perspective view of the dehydration aids A, B, E, and G. FIG. There are a plurality of recesses in the fiber cross section, and there are lines extending in the fiber length direction at the recesses.

5 is a perspective view of the dehydration aids C and D. FIG. There are a plurality of recesses in the fiber cross section, and there are lines extending in the fiber length direction at the recesses.

6 is a perspective view of the dehydration aid F. FIG. There are a plurality of recesses in the fiber cross section, and there are lines extending in the fiber length direction at the recesses.

7 is a perspective view of the dehydration aid H. FIG. There are a plurality of recesses in the fiber cross section, and there are lines extending in the fiber length direction at the recesses.

8 is a perspective view of the dehydration aid I. FIG. There are a plurality of recesses in the fiber cross section, but there is no line extending along the fiber length direction.

9 is a perspective view of the dehydration aids J and K. FIG. There is no recess in the fiber cross section, and there is no line extending along the fiber length direction.

Example 1 (Comparison with or Without Dehydration Aid of the Present Invention)

The sludge slurry was adjusted by adding the dehydration aid A to the excess sludge slurry generated from the oxidative-sphere type sewage treatment plant which has the properties shown in Table 2 so that SS may be set to 100, and it may become 3 wt% at dry weight. Next, the dehydration test was done using the polymer coagulant (methyl chloride quaternized substance of dimethylamino ethyl acrylate / acrylamide copolymer, molecular weight 4 million, adjusted to 0.2% with tap water). 200 ml of sludge was put into a 300 ml beaker, and a predetermined amount of a polymer flocculent was added, and then the sludge was aggregated by performing the movement between beakers 10 times. After the size of the flocculated sludge was measured, the flocculated sludge was placed on a nylon mesh cloth of 60 mesh, dehydrated by gravity, and the amount of filtration after 30 seconds was measured. The sludge after gravity filtration was sandwiched between two filter cloths and pressed for 1 minute at a pressure of 2 kg / cm 2 using a piston type dehydrator. The peelability of the obtained dehydrated cake was evaluated and the water content was measured. Peelability evaluation is when the two filter cloths are opened after dehydration, the amount of cake peeled off from the filter cloth is visually measured. (Circle) and the case where it was not peeled off were attached to the whole filter cloth whole surface, and were judged as x more. The results are shown in Table 3.

[Comparative Examples 1 and 2]

The dehydration test was done without adding a dehydration aid. Compared with Example 1, the cake moisture content was 2-3 points higher. The results are written together in Table 3.

Examples 2 to 9 (Other Embodiments of the Invention)

The test was carried out similarly to Example 1 except having used the dehydration adjuvant shown in Table 4 instead of the dehydration adjuvant A, and changing the addition rate of a dehydration adjuvant. The results are shown in Table 4.

[Comparative Examples 3-6] (Comparison of Dehydration Aids)

Dehydration adjuvant H, I, and K were added, and the dehydration test was done like Example 1. Dispersion into sludge was poor, and the cake moisture content was increased by 2 points or more (comparison of Example 2 and Comparative Examples 5 and 6, or comparison of Examples 5 and 6 and Comparative Example 4). The results are written together in Table 4.

Example 10 (Comparison with or Without Dehydration Aid of the Present Invention)

To the digested sludge resulting from the sewage treatment plant of Table 5, 2 wt% of the dehydration aid C was added at a dry weight with SS as 100 to prepare a sludge slurry. Next, the dehydration test was done like Example 1 using the polymeric flocculant (methyl chloride quaternary polymer of dimethylaminoethyl acrylate, molecular weight 3 million, adjusted to 0.2% with tap water). The results are shown in Table 6.

[Comparative Examples 7, 8]

The dehydration test was done without adding dehydration aid C. Compared with Example 10, the cake moisture content was increased by at least 3 points. The results are written together in Table 6.

[Examples 11 to 15] (Other Embodiments of the Present Invention)

The test was carried out similarly to Example 10 except having used the dehydration adjuvant shown in Table 1 instead of the dehydration adjuvant C. The results are shown in Table 7.

[Comparative Examples 9-14] (Comparison of Dehydration Aids)

Dehydration aids I and J were added and the dehydration test was done like Example 10. Dispersion of sludge was poor, and the cake moisture content was increased by 2 points or more. The results are written together in Table 7.

[Examples 16-21] (Comparison with Addition to Polymer Coagulant Dissolving Solution and With or Without Dehydration Aid of the Present Invention, Practical Test in Screw Press Dehydrator)

<Beaker test>

While stirring 1 L of 0.2% aqueous solution of the polymer flocculant used in Example 1 at 200 rpm using a tester, 3 g of dehydration aids A, D, and E were each dried at a dry weight (1.5 times the dissolved polymer flocculant), and 1 Stirring was continued. The dispersion state and fluidity of the dehydration aid in the solution after 1 hour were observed. The results are shown in Table 8.

<Practical examination>

Next, a 0.2% aqueous solution (tap water) of the polymer flocculant used in Example 1 and a 1.5 times dehydration aid of the polymer flocculant were added to the polymer flocculant dissolving tank, followed by stirring and mixing to prepare a dehydration aid-containing polymer flocculant liquid.

Subsequently, the mixed sludge slurry of the excess sludge and the flocculation sedimentation sludge generated from the manure treatment facility shown in Table 9 was supplied to a screw press dehydrator (screen diameter 300 mm Φ) shown in FIG. 2 through a flocculation tank and dewatered. As a coagulation tank, the prepared dehydration adjuvant containing polymer coagulant liquid was added using the monopump, and the sludge slurry was aggregated. In the screw press dehydrator, dehydration was performed on condition of a screw rotation speed of 0.4 rpm, the leakage state from the punching metal of the flocculated sludge was observed, and the moisture content of the dehydration cake was measured. The results are shown in Table 10.

[Comparative Examples 14, 15]

The test was carried out in the same manner as in Example 16 except that the polymer flocculant alone was dehydrated and no dehydration aid was used. The results are shown in Table 10.

[Comparative Examples 16 ~ 17]

The polymer flocculant and the dehydration adjuvant were mixed similarly to Examples 16-21 except having used dehydration adjuvant I and J. The results are shown in Table 11. The dehydration aids I and J were not uniformly dispersed in the polymer coagulant aqueous solution, and therefore, the test was not carried out in the following practical device.

As shown in Table 11, when the dehydration aid is not uniformly dispersed or the fluidity of the solution is poor, the amount of discharge from the chemical injection pump cannot be kept constant with the dehydration aid-containing polymer coagulant pump. In addition, there is a possibility of causing the occlusion of the other medicine line, it can be seen that it is inappropriate for such use.

Exam No Dehydration Supplement Type Dispersion State and Liquidity Comparative Example 16 I Dispersed uniformly, but poor fluidity due to high viscosity of solution. Comparative Example 17 J Can see lumps that are not partially scattered.

1: sludge concentration tank 2: sludge storage tank
3, 3-1, 3-2: flocculation tank 4: belt press dehydrator
5: dehydration aid feeder 6: polymer condensing agent dissolving device
7: screw press dehydrator 8: filtration concentrate
9: dehydration aid supply path 10: polymer flocculant supply path

Claims (14)

A plurality of fibers are assembled
On the outer circumferential surface of each fiber has 5 to 20 concave portions extending along the longitudinal direction of the fiber,
A dehydration aid for sludge, characterized in that the concave portion extends along a longitudinal direction of the fiber, the line serving as a water transfer path for transferring moisture by capillary action when the sludge contacts. The method of claim 1,
A dehydration adjuvant for sludge, characterized in that the regenerated cellulose fibers are collected and have a water content of 30 to 80 mass%. The method of claim 1,
Dehydration aid for sludge which has a length of 1 mm-50 mm and a fiber diameter of 1 micrometer-100 micrometers. A plurality of regenerated cellulose fibers are assembled and
On the outer circumferential surface of each fiber has 5 to 20 concave portions formed along the longitudinal direction of the fiber,
In the concave portion, a line acting as a water transfer path for transferring moisture by capillary action when the sludge contacts is extended along the longitudinal direction of the fiber,
Dehydration aid for sludge having a water content of 30 to 80 mass%. The method of claim 4, wherein
Dehydration aid for sludge which has a length of 1 mm-50 mm and a fiber diameter of 1 micrometer-100 micrometers. It consists of a plurality of fibers, and has 5 to 20 recesses formed along the longitudinal direction of the fibers on the outer circumferential surface of each fiber, wherein the moisture transfers moisture by capillary action when sludge contacts. After the dehydration adjuvant for sludge is added and mixed with organic sludge, the line acting as a conveyance path extends along the longitudinal direction of the fiber, and then the polymer sludge is added to coagulate the organic sludge, followed by mechanical dewatering. Dewatering method of sludge characterized by It consists of a plurality of fibers, and has 5 to 20 recesses formed along the longitudinal direction of the fibers on the outer circumferential surface of each fiber, wherein the moisture transfers moisture by capillary action when sludge contacts. A dehydration aid-containing polymer coagulant liquid formed by mixing a dehydration aid for sludge and a polymer flocculant, wherein the line acting as a conveying path extends along the longitudinal direction of the fiber, is added to the organic sludge to aggregate the organic sludge. Dewatering method of sludge characterized by dehydrating a machine after making it let. It consists of a plurality of fibers, and has 5 to 20 recesses formed along the longitudinal direction of the fibers on the outer circumferential surface of each fiber, wherein the moisture transfers moisture by capillary action when sludge contacts. The dehydration aid for sludge and the polymer flocculant are added to an organic sludge at the same time by the line acting as a conveyance path extending along the longitudinal direction of a fiber, and the said organic sludge is aggregated, and mechanical dewatering is carried out, It is characterized by the above-mentioned. How to dehydrate sludge. 9. The method according to any one of claims 6 to 8,
Said mechanical dehydration is performed with a screw press dehydrator, The sludge dewatering method characterized by the above-mentioned. It consists of a plurality of fibers, and has 5 to 20 recesses formed along the longitudinal direction of the fibers on the outer circumferential surface of each fiber, wherein the moisture transfers moisture by capillary action when sludge contacts. In the apparatus for adding a sludge dehydration adjuvant to the organic sludge and mechanically dewatering the organic sludge, characterized in that a line acting as a conveying path extends along the length direction of the fiber.
A sludge storage tank, a flocculation tank, a mechanical dehydrator, a dehydration aid feeder for supplying a dehydration aid for organic sludge sludge, and a polymer flocculant dissolving device for dissolving the polymer flocculant supplied to the flocculation tank,
The polymer coagulant dissolving device is a sludge dewatering device connected to the coagulation tank via a pipe. The method of claim 10,
A sludge dewatering apparatus, wherein a sludge thickening tank is provided at a front end of the sludge storage tank, and the dehydration auxiliary feeder is connected to the sludge thickening tank via a pipe. The method of claim 10,
Sludge dewatering apparatus provided with a filtration concentration unit between the coagulation tank and the mechanical dehydrator. The method of claim 10,
The dewatering apparatus of sludge whose said machine dehydration apparatus is a screw press dehydrator. The method of claim 10,
The dehydration aid supply device is a dewatering device of sludge connected to at least one of the sludge storage tank, the flocculation tank, the mechanical dehydrator, or the polymer flocculant dissolving device.

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