JPS60197299A - Dehydration assistant and method - Google Patents

Abstract

PURPOSE:To obtain a combustible press dehydration assistant added to sludge and dehydrating said sludge with good efficiency, by mixing an org. fibrous substance and a cationic high-molecular flocculant and molding the resulting mixture under pressure to obtain density of 0.3g/cm<3> or more. CONSTITUTION:An org. fibrous substance and a cationic high-molecular flocculant are mixed and the resulting mixture is press molded so as to obtain density of 0.3g/cm<3> or more to prepare the dehydration aid of sludge. This dehydration aid is added to sludge in an amount of 0.5-200% by wt. of the solid of said sludge to perform press dehydration. As the aforementioned org. substance, a natural fiber, an artificial fiber, a synthetic fiber or a mixture consisting of two or more kinds of said fibers are used. As the cationic high-molecular flocculant, there are cation modified polyacrylamide, chitosan, polyvinyl imidazoline or polydiarylamine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aid for pressurized dewatering of sludge and a dewatering method. More specifically, it relates to a combustible pressurized dehydration aid that efficiently dewaters sludge and a pressurized dehydration method. Ferric chloride as a dewatering aid for pressurized dehydration of sludge.

Inorganic flocculants such as slaked lime or polymer flocculants are used, but there is no method using inorganic flocculants.

There are problems such as a large amount of fuel is required to incinerate the dehydrated cake, and there is a large amount of ash when incinerated, and polymer flocculants do not lower the moisture content of the dehydrated cake sufficiently and have poor releasability from P cloth. However, none of the methods are necessarily satisfactory. There is also a method of simply mixing or using a polymer flocculant with fibers, etc., but in this case as well, the moisture content of the dehydrated cake and the peelability from the P cloth are insufficient, and the fiber quality is bulky. Large-scale equipment is required for storage and transportation.

It takes time to use. There were problems such as not being able to obtain stable effects.

The present inventors have conducted intensive studies aimed at solving the above-mentioned problems, and as a result, have arrived at the present invention. That is, 1. the present invention provides a mixture of an organic fibrous material and a cationic polymer flocculant with a density of OJg.
A pressurized dewatering aid for sludge (first invention) characterized by being formed by pressure molding to a size of 0.5 to 200% by weight based on the solid matter of the sludge. This is a pressurized dewatering method for sludge (second invention), which is characterized by adding and pressurizing dewatering.

In the present invention, organic fibrous materials (hereinafter simply referred to as fibers) include natural fibers (cellulose-based materials (e.g., cotton, sawdust, straw, etc.) and others, grass charcoal, wool, etc.), artificial fibers (cellulose-based materials, e.g. , rayon, acetate, etc.) 1 Synthetic fibers (polyamide, polyester, acrylic, etc.) and two or more of these 0
One example is the 1-use system. Among these, the preferred one is
They are cellulosic natural fibers (sawdust, cotton, straw) and grass charcoal.

In addition, the fibers can be in the form of powder; fibers, such as cut single fibers (usually less than 100 denier in thickness), bundles of fibers, treated with a suitable binding agent and cut, fibers, etc. Examples include those obtained by bundling a plurality of fibers and cutting them into a thread, cutting a single woven fabric or non-woven fabric from the same, or loosening the same.

The length of the fiber is not particularly limited, but is usually 0.01 to 5.
0 mm + preferably o, i ~ 80 mm. Also,
The moisture content of the fibers is preferably 30% or less, more preferably 15% or less.

Regarding the pulp, the present applicant
A patent application (υ (title of invention: dehydration aid and dehydration method) was filed on the date of this publication, and it is excluded from the fibers in the present invention.

The cationic polymer flocculant used in the present invention may be a commonly used commercially available product, such as cationically modified polyacrylamide (Mannich modified product, Hoffman modified product, etc.), chitosan, polyvinylimidacillin, polydiallylamine, polyethyleneimine. , polyvinylpyridine,
Cationized starch, epichlorohydrin-amine condensate, salt (co)polymer of tertiary nitrogen-containing (meth)acrylate or (meth)acrylamide and acid, quaternary nitrogen-containing (meth)acrylate or (meth)acrylamide (co) Examples include polymers and mixtures of two or more thereof.

Salt (co)polymers of 8th class nitrogen-containing (meth)acrylates or (meth)acrylamide and acids and quaternary nitrogen-containing (meth)acrylates or (meth)acrylamide (co)polymers include JP-A-54-102888. Examples include those described in the No.

Specifically, the general formula (wherein A is an oxygen atom or NH, B is an alkylene group having 1 to 4 carbon atoms, a hydroxyalkylene group having 2 to 4 carbon atoms, or a phenylene group i, R1 is H or methyl JJs
, R2, RA, lt4 represents H, an alkyl group or an aralkyl group, and Xe represents a counter anion. ) Water-soluble (co)polymers having units shown in the following are mentioned.

Specifically, dialkylaminoalkyl (meth)acrylates (dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 3-dimethylamino-2-hydroxypropyl (meth)acrylate, etc.), dialkylaminoalkyl (meth)acrylate, etc. ) Acrylamides (dimethylaminoethyl (meth)acrylamide.

Inorganic acid salts (hydrochloride, sulfate, etc.) such as 8-dimethylamino-2-hydroxypropylacrylamide,
Organic acid salts (such as acetate) or quaternizing agents (methyl chloride,
(co)polymers of quaternary ammonium salts (dimethyl sulfate, benzyl chloride, etc.); and inorganic acid salts of dialkylaminoalkyl (meth)acrylates or dialkylaminoalkyl (meth)acrylamides;
Quaternary ammonium salts and other vinyl monomers ((meth)acrylamide N by organic acid salts or quaternizing agents).

N-dimethylacrylamide, acrylonitrile.

Examples include copolymers with styrene, vinyl acetate, etc., and mixtures of two or more of these.

Among these, preferred are Mannich-modified polyacrylamide and polyvinylimidacillin.

Chitosan, polydiallylamine, tertiary nitrogen containing (meth)
These are a salt (co)polymer of acrylate or (meth)acrylamide and an acid, and a quaternary nitrogen-containing (meth)acrylate or (meth)acrylamide (co)polymer.

Furthermore, among the above cationic polymer flocculants.

Its intrinsic viscosity [η) dl/g (hereinafter expressed as [η]) and colloidal equivalent value Cmeq/g (hereinafter expressed as C) are expressed by the formula % formula % (21 [wherein, Coo, [η]] 0, and [η] is preferably in the range shown in (measured in an IN NaNO3 aqueous solution at 30°C). When [η] is outside the above range, a sufficient dewatering effect cannot be obtained when it is added to and mixed with sludge for dewatering.

In the present invention, the cationic polymer flocculant is preferably in powder form, but the flocculant is in the form of an aqueous solution or emulsion (concentration is usually 2% by weight or more, preferably 2% by weight or more
0 weight Φ or more) can also be used. Among powders, powders with a water content of 80% or less are preferable, and those with a water content of 15% or less are preferable.

The mixing ratio of the cationic polymer flocculant and the fibers is not particularly limited and can be arbitrarily selected depending on the target sludge, but the weight ratio is usually 1:0.05~1000°, preferably 1:0.1~ 500. More preferably 1:1-1
It is 00. If the fiber content is less than 01, the removability of the cake from the furnace cloth after being added to sludge and dehydrated will be poor.

If it exceeds 1000, it becomes uneconomical. In addition, the amount of fiber added per solid matter of sludge is usually 0.5 to 200%.
, preferably 1 to 100%, and the cationic polymer flocculant (solid content) is usually 0.05 to 3%, preferably 0.
It is 1-2.0%.

In the present invention, a mixture of fibers and a cationic polymer flocculant (hereinafter also referred to as flocculant) may optionally contain known filter aids (pulverized coal, bentonite diatomaceous earth, kaolin, celite, activated clay 1 lime, etc.). ), dispersants (surfactants, inorganic salts, etc.), 6 deodorants, antifoaming agents, etc. can also be contained in amounts that are not dominant to the fibers. As the surfactant, known anionic, cationic, amphoteric, and nonionic surfactants can be used, but cationic and nonionic surfactants are preferred, and 1-8 class salts of long-chain alkyl amines, or More preferred are cationic surfactants such as quaternary ammonium salts. The inorganic salt may be any one, and is not particularly limited, and includes, for example, common salt, sulfur sulfate, ammonium sulfate, ferric chloride, polyaluminum chloride (PAC), aluminum sulfate, and the like.

In the present invention, the total amount of fibers and flocculant in the mixture is usually 50% by weight or more, preferably 60% by weight or more.

The mixture of fibers (2) and flocculant (5) contains (2)
and mixtures of (2) and CB). The method for obtaining the mixture of (2) and CB) is not particularly limited, but for example, pulverized (2) and (8) are mixed using a mechanical mixing device (Nauta mixer, ribbon mixer,
A method of mixing with a conical blender, mortar mixer, etc.), JP-A-56-89889 or JP-A-58-
Examples include the method of mixing described in No. 8175 [using (2) in place of the water-absorbing resin]. In addition, as a method to obtain a composite of (2) and [F]), (2) is crushed.
Laminated in sheet form, S) or (printed and crushed (
Sprinkle the mixture of 2) and pulverize it on top of it (2)
Examples include a method of laminating them into sheets. These mixtures and composites can be used in a dry state (e.g.

It is preferable in terms of performance to produce the product in a state in which the water content of (4) and (4) does not increase.

The obtained mixture is pressure molded to a density of 0.3 g/Cm3 or more. This pressure-molded product can be transported more economically.

Considering storage, the density is 0.5g/cm
If the density is less than 0.8 g/cm3, when it is added to sludge and dehydrated, the water content of the dehydrated cake will not be sufficiently reduced.

Also, the cake is difficult to peel off from the oven cloth. Further, from the viewpoint of performance, the moisture content of the press-molded product is preferably 80% or less, and more preferably 15Φ or less.

Pressure molding methods include pressurizing the mixture into pellets in a mold at room temperature, sheet-forming at room temperature,
An example is a method in which the material is pressure-molded into a rod or block shape and then cut or crushed into an appropriate size. In the above, pressurization may be carried out under heating (for example, 20 to 80%), humidification (for example, 60 to 100%), or in a dry state, but it is preferable to carry out in a dry state in view of the performance of the molded product obtained. .

The pressure during pressure molding is such that the density of the obtained pressure molded product is 0.8
It is sufficient if the pressure is at least g/cm3.

It can be selected appropriately depending on the type, form, properties, etc. of the fiber, but it is usually 1 to 2000 kg/cm2 *preferably 10 to 1500 kg/cm2.For pressure forming, a roll press machine, a flat plate press machine, screw press machine.

This can be carried out using an extruder press machine or the like.

The shape of the obtained press-molded product may be arbitrary and includes various shapes such as one spherical shape, one cylindrical shape, a cube shape, a rectangular shape, a charcoal shape, one conical shape, a rod shape, and a plate shape.

The size of the press-molded product is such that the shortest axis of the press-molded product is usually 10 cm or less, preferably 8 cm or less. If the shortest diameter is longer than 10 cm, when added to sludge,
It takes time to disperse the dehydration aid, making it difficult to obtain a sufficient dehydration effect in a short period of time. The longest diameter is not particularly limited, but is preferably 1 m or less and tmm or more (especially 2 mm or more).

The press-formed product thus obtained is added to sludge,
Used as a dewatering aid when dewatering sludge.

When adding a dewatering aid to sludge, the target sludge may be any sludge, such as raw sludge such as sewage, human waste, or industrial wastewater, activated sludge, digested sludge, coagulated sedimentation sludge, or mixed sludge made from a combination thereof. Sludge obtained through microbial treatment (activated sludge) is good.

(digested sludge, etc.), the organic content in the sludge is 40 weight Φ or more per solid content, and the organic fiber content in the sludge is 20 weight %
The following sludges that are difficult to filter are particularly effective.

The amount of the dewatering aid of the present invention added to the sludge is usually 0.5 to 200% by weight, preferably 1 to 100% by weight, based on the solids of the sludge.
% by weight, particularly preferably from 2 to 50% by weight. If the amount added is less than 0.5%, the dehydration effect will be insufficient;
If it exceeds 00 type, it becomes uneconomical.

When adding the dewatering aid to the sludge, it is also possible to add a dispersant such as an inorganic salt or a surfactant before or at the same time to further accelerate the dispersion of the dewatering aid. Furthermore, the sewage sludge can be deodorized by adding a commercially available deodorizing agent.
The dewatering aid of the present invention is directly added to sludge, and the floc diameter is adjusted to 0.1 to 20 mm + preferably O-5 to 15 mm.

When a dewatering aid is added to sludge, the floc diameter is 0.1 m.
If it is smaller than m, clogging of Pm occurs during pressurized dehydration, and dehydration often becomes impossible during the process. Furthermore, if the floc diameter is larger than 20 mm, the moisture content of the cake after dehydration will not be sufficiently reduced, and the releasability from the P cloth will also be poor.

One method for adjusting the floc diameter is to directly add and mix the dewatering aid to the sludge, and then perform normal stirring or gentle stirring (for example, 30 to 800 rpm, 10 to 600 seconds) to form flocs. The stirring method may be any method (method using a two-blade stirrer, a stirrer equipped with a chi-shape stirring rod, a Satake-type stirrer, etc.).

There are no particular limitations.

Dehydration then takes place. In this case, the water is dehydrated using a pressure dehydrator. The pressurized dehydrator used may be one that has a mechanism for dehydrating under pressure.

Examples include filter presses, belt presses, capillary roll presses, screw presses, etc. Among these, filter presses, belt presses, and screw presses are particularly good, as they reduce the moisture content of the cake after dehydration well and have good peelability of the cake.

Alternatively, the sludge to which the dewatering aid has been added may be lightly pre-dehydrated using gravity dehydration or an appropriate dehydrator, and then subjected to the pressure dehydrator.

The dehydrated cake is incinerated or the like by a known method. It is also extremely easy to convert it into fuel and compost (fertilizer).

The method of using the auxiliary agent of the present invention is to mix and suspend fibers in an aqueous solution of a flocculant and add it to the sludge, or to add a mixture of fibers and a flocculant to water to the sludge, and further to flocculate. Compared to methods in which the agent and fibers are added to the sludge separately, the dewatering performance is unexpectedly improved significantly (the water content of the dehydrated cake is lowered and the peelability from the furnace cloth is improved). Moreover, the product obtained by pressure-molding the flocculant and the fibers has a high density, so it has the advantage that it can be stored and transported efficiently and economically.

Furthermore, compared to conventional pressurized dehydration methods using inorganic flocculants or polymer flocculants, it is possible to obtain dehydration effects (moisture content of cake, releasability from furnace cloth) that are superior to those methods. For these reasons, the present invention has extremely high practical value.

The present invention will be further explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 and Comparative Example 1 Sawdust and methachloroyloxyethyltrimethylammonium chloride polymer (hereinafter referred to as METAC polymer. [η) = 5.8 d l/g, C = 4
．． 8 meq/g) of powder at the blending ratio shown in Table 1, and press at 1000 kg/cm2 with a hydraulic plate press at room temperature.
The mixture was pressurized to produce pellets of a predetermined size (specific gravity: 0.9) to obtain the auxiliary agent of the present invention.

200 g of mixed raw sludge from the sewage treatment plant of City A was collected in an 800 mg beaker (solid content: 2.6% by weight, organic content: 71%).
The pellets prepared above were directly added to the mixture (8% by weight/solid content, 3.9% by weight/solids fiber content) and stirred for 30 seconds at 25 Orpm using a small experimental stirrer equipped with a 6-shape stirring rod. °C flocs were formed. [Flock diameter (mm)
) Measurement] The flock in the beaker prepared above was poured onto a metsche covered with a furnace cloth, and the amount of P liquid (me) was measured after 10 seconds.

The filtered and dehydrated cake on the metsche was sandwiched between two pieces of furnace cloth and was pressed to 1 kg/c using a small belt press experimental machine.
Pressure dehydration was performed for 60 seconds at m2. The peelability of the cake from the oven cloth and the water content (wt%) of the dehydrated cake were measured. The results are shown in Table 1.

As Comparative Example 1, in the same manner as in Example 1, nothing was added to the sludge, pellets of only sawdust were added, only a polymer flocculant was added, and sawdust and METAC polymer were added without pelletizing. A test was conducted on the product added to sludge as it was, and the results are also listed in Table 1.

Table 1 Table 1 (Continued) *l Good peelability of cake after dehydration...The cake was peeled off almost completely and the oven cloth was not clogged.

Fair: Peeling is insufficient and some cake remains on the oven cloth. Some of the furnace cloths are clogged.

Not possible: After peeling off, a considerable amount of cake remains on the P layer. Almost the entire area of the furnace cloth is clogged.

Procedural amendment (formality) 1. Display of incidents 1980, Kenkyori No. 53956 2. Name of the invention Dehydration aids and dehydration methods 3. Those who have 1 correction June 6, 1982 5. Number of inventions increases by h1° due to amendment First, submit the typewritten statement as shown in the attached sheet.

There are no changes to the content.

Claims (1)

[Claims] 1. Pressure dewatering of sludge, characterized in that it is made of a mixture of an organic fibrous material and a cationic polymer flocculant that is pressure-molded to a density of 0.8 g/Cm3 or more. Use aids. 2. Add 05 to 200% by weight of a mixture of organic fibrous material and cationic polymer flocculant to a density of OJg/cm3 or more to the solid sludge, and pressurize and dewater. A pressurized dewatering method for sludge that is characterized by: