JP2003053182A - Dewatering aid and dewatering method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dewatering aide which allows biological decomposition utilizable as raw material of compost and a dewatering method using the same. SOLUTION: This dewatering aide comprises natural fiber 100 pts.wt. having a thickness of several μm to 1 mm and a length of 1 mm to several cm and water soluble natural polymer chemical 2-10 pts.wt. Further, in this dewatering method of liquid waste, the natural fiber is the remains of plant, the water soluble polymer chemical is biodegradable one such as carboxymethylcellulose salt, alginic acid salt and polyvinyl alcohol and, further, the dewatering assitant is added to liquid waste and is mixed and, thereafter, dewatering treatment is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to dehydration of liquid waste, and more particularly to liquid waste such as sludge and organic waste such as kitchen waste generated by wastewater treatment of sewage, night soil, industrial wastewater and the like. The present invention relates to a dehydrating auxiliary agent for dehydrating a product and a dehydrating method using the same.

[0002]

2. Description of the Related Art Dewatering is indispensable for treating and disposing of organic wastes such as surplus sludge, coagulated sedimentation sludge, and garbage generated by wastewater treatment such as sewage, night soil and industrial wastewater. As a method of dehydrating liquid waste, etc., it is common to add an organic polymer coagulant or an organic polymer coagulant and an inorganic coagulant to the liquid waste, coagulate the liquid waste, and then dehydrate it with a dehydrator. Is. On the other hand, most of the dehydrated dehydrated cake is incinerated, but considering the reuse of the dehydrated cake in the future, composting is the preferred disposal method. In composting, it is important that the drugs used in the dehydration process can be decomposed by microorganisms.

The conventional techniques are shown below. (1) A method of adsorbing and removing high molecular weight molecules and particles such as proteins by using cellulose fibers obtained by refining a plant-derived cellulose material such as wood pulp to a thickness of 1 μm or less has been proposed. (2) Auxiliary agent for pressure dehydration of sludge pressure-molded with organic fiber materials such as natural fiber and artificial fiber, and cationic polymer flocculant, and dehydration method using the auxiliary agent Has been done.

(3) An inorganic fiber such as asbestos having a length of 2 to 30 mm, a natural organic fiber, an artificial fiber, a synthetic fiber, a carbon fiber, a metal fiber and an inorganic coagulant or a polymer coagulant are added to and mixed with sludge. , A method of dehydrating sludge has been proposed. Fibers whose surface has been treated with a cationic surfactant or dispersant or untreated can also be used. (4) A method of dehydrating sludge in which a water-soluble organic polymer compound such as sodium alginate or polyvinyl alcohol and a fibrous substance are mixed with sludge and treated with an insolubilizer has been proposed. Fibrous substances include fibrous minerals such as asbestos, synthetic fibers, natural fibers, chemical fibers such as carbon fibers, semi-synthetic fibers, recycled fibers, pulp and the like. The insolubilizer is a compound that produces an inorganic polyvalent cation. The water-soluble organic polymer compound and the fibrous substance are characteristically mixed in advance.

The above-mentioned conventionally proposed method has the following problems. (1) Micronized cellulose fibers are used for the purpose of adsorbing and removing polymer substances, but if this is used as a dehydration aid, the sludge particle adsorbability is good and the cellulose fibers are biodegradable. However, since the affinity between the cellulose fiber and the moisture in the sludge particles is good, the dehydration property is lowered and the cellulose fiber itself is expensive. (2) Since the pressure dehydration aid for sludge pressure-formed with the organic fiber substance and the cationic polymer flocculant is a dehydration aid for pressure dehydration, it is suitable for use in the dehydration process. narrow. Although natural fiber itself has biodegradability, the biodegradability of the polymer flocculant is unknown, and the safety of compost remains questionable.

(3) Natural organic fibers are also used in the method of dehydrating fibers such as inorganic fibers and synthetic fibers, and inorganic coagulants and polymer coagulants as a dehydration aid, which is biodegradable. is there. However, the surfactant for hydrophilizing the hydrophobic natural organic fiber contributes to the improvement of the cohesiveness of the sludge and is not for the added natural organic fiber to be compatible with the sludge. It is important to mix the fully hydrophilized fiber and sludge. (4) A method for dehydrating sludge in which a water-soluble organic polymer compound and a fibrous substance are mixed and treated with an insolubilizing agent is that an insolubilizing agent which is an inorganic compound is added to sludge as a raw material for composting. Not only can you disassemble with
It is not a good idea because the metal present in the inorganic compound fixes phosphorus, which is a fertilizer component.

[0007]

DISCLOSURE OF THE INVENTION In view of the above-mentioned prior art, the present invention provides a liquid waste in which the dehydrated cake is biodegradable for all chemicals used for dehydration so that it can be used as a raw material for compost. An object of the present invention is to provide a dehydration aid capable of effectively dehydrating a product and a dehydration method using the same.

[0008]

In order to solve the above problems, the present invention has a thickness of several μm to 1 mm and a length of 1 mm.
It is used as a dehydration aid consisting of 100 parts by weight of natural fiber of several cm to 2 to 10 parts by weight of a water-soluble natural polymer drug. In the dehydration aid, the natural fiber is a plant remains, and the water-soluble natural polymer agent is preferably a biodegradable one such as a salt of carboxymethyl cellulose, alginate or polyvinyl alcohol. Further, the present invention provides a method for dehydrating liquid waste, which comprises adding and mixing the above-mentioned dehydrating aid to liquid waste, and then performing dehydration treatment.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The natural fiber used in the present invention is wood pulp of papermaking raw material, cotton recovered by recycling, kenaf fiber, sugarcane squeeze, reeds of aquatic plants, plant fibers such as hemp, plant remains such as humus and peat moss. . Plant remains such as humus soil and peat moss are preferable because they are inexpensive, have a stable supply, and do not affect the quality of product compost even if they remain in the composting process. In addition, the natural fiber of the plant remains is preferable because its shape is irregular and its surface is rich in irregularities, and it is easy to hold the solid matter in the liquid waste and the natural polymer drug which is a hydrophilic agent described later. is there. The shape of natural fiber is
The thickness is several μm to 1 mm, and the length is 1 mm to several cm.
The smaller the thickness, the better the dehydration performance, but it is difficult to newly process the natural fiber. Since the length affects handling, it is preferable that the length is several mm to 1 cm in consideration of workability when the slurry is formed.

The water-soluble natural polymer drug of the present invention is one which can make the surface of natural fiber hydrophilic and can decompose the natural polymer drug by aerobic microorganisms during compost production or by soil bacteria after composting. Point to. It may be a food additive such as a thickener, a binder or an emulsion stabilizer. As a method of impregnating a natural polymer with a natural polymer drug, the natural fiber is immersed in the natural polymer drug or an aqueous solution thereof, and then drained or dehydrated with a wire net such as a screen.
Further, it may be naturally dried after the immersion. The water content of natural fibers has a great influence on workability such as mixing of liquid waste and natural fibers and prevention of dust generation at the time of addition. The water content of the natural fibers is 5 to 20% per dry natural fiber. The water content of the natural fiber may be simply water content, or the water-soluble natural polymer agent of the present invention having hydrophilicity may be added at an addition rate described below, and the rest may be water content. In the case of water, if it is less than 5% based on dry natural fiber, deterioration of workability due to dust and mixing with liquid waste pose problems. Also, when it exceeds 20%,
The water content is high and transportation costs are high, and water leaching becomes a problem.

The content of the natural polymer drug in the natural fiber is 2 to 100 parts by weight of the dry natural fiber.
10 parts by weight. If the content of the natural polymer agent in the natural fiber exceeds 10 parts by weight, the fibers of the natural fiber impregnated with the natural polymer agent may stick to each other, resulting in poor workability. If it is less than 2 parts by weight, the effect of improving hydrophilicity is low. However, even if the amount is less than 2 parts by weight, in a liquid waste containing a large amount of protein derived from activated sludge, such as excess sludge, and having a polysaccharide called extracellular polymer,
Since the liquid waste itself imparts hydrophilicity to the natural fibers, there is no problem in the mixing or dehydrating effect of the liquid waste and the natural fibers of the present invention even if the content of the natural polymer drug is low. On the other hand, natural fibers not impregnated with natural polymer agents are slurried,
A natural polymer drug may be added to the slurry at a predetermined concentration. The natural fiber hydrophilized by the natural polymer drug may be added to the liquid waste as a powder or may be added in the form of a slurry. Slurrying can be facilitated by hydrophilizing natural fibers with a natural polymer agent.

In view of workability and simplification of drug injection equipment, the method of the present invention using natural fiber impregnated with a natural polymer drug is preferable. The natural polymer drug of the present invention is
Specifically, CMC (carboxymethyl cellulose) sodium salt, water-soluble cellulose derivatives such as methyl cellulose, sodium starch glycolate, sodium alginate, polysaccharides and starch sugars, agar, gelatin,
Funori, PVA (polyvinyl alcohol), saponin,
Examples include chitosan, chitin and sorbit. Any one or more of the above water-soluble natural polymer drugs can be mixed to impregnate natural fibers. An existing pulper or mechanical stirrer can be used as a crushing method for making natural fibers into a slurry. Further, in the method for dehydrating liquid waste of the present invention using the above dehydration aid, an organic polymer coagulant or an inorganic coagulant can be used as a coagulant as in the conventional case. A commercially available dehydrator can be used,
Any of belt press type, screw press type, centrifugal separation, and filter press type can be used.

[0013]

The present invention will be described in detail below, but the present invention is not limited thereto. Reference Example 1 A predetermined amount of natural fiber or synthetic fiber is added to sewage mixed sludge,
After coagulating with a dimethylaminoethyl acrylate-based cationic polymer coagulant, dehydration treatment was performed with a belt press dehydrator. The properties of the sewage mixed sludge are as shown in Table 1 below.

[Table 1]

Among natural fibers, peat moss has a thickness of about 5
Made in Canada with a length of 0 μm and a length of 5 mm to 15 mm, cotton is a recycled fiber of clothing and cut into a thickness of 50 to 100 μm and a length of 10 mm. Synthetic fibers are fibers regenerated from plastic bottles, and their shape is 1 in thickness.
The length is 0 to 15 μm and the length is 10 mm. These were added to tap water so as to be a 5% slurry and crushed for 5 minutes with a juicer mixer. The specifications and operating conditions of the belt press type dehydrator are shown in Table 2 below.

[Table 2]

Table 3 shows the results of Reference Example 1. Both the natural fiber and the synthetic fiber as the dewatering aid had a low water content, and the dewatering cake peeled from the filter cloth was good.

[Table 3]

Example 1 Using the sewage-mixed sludge of Reference Example 1, a dehydration aid produced by adding a natural polymer agent to the peat moss, cotton or PET recycled fiber of Reference Example 1 was mixed, and then Reference Example 1 A dehydration test was conducted in the same manner as in. The results are shown in Table 4.

[Table 4]

REFERENCE EXAMPLE 2 Cellulose fiber and sewage mixture in sewage mixed sludge of Reference Example 1
The pellets obtained by press-molding peat moss were added and dehydrated under the conditions of Reference Example 1. As the cellulose fiber, a commercially available viscose rayon fiber having a thickness of about 1 μm and a length of 10 mm was used. The pressure-molded pellets of peat moss were obtained by mixing peat moss with the cationic polymer flocculant of Reference Example 1 and using a hydraulic press machine at 10 MPa at a diameter of about 5 mm and a length of about 5 m.
It was processed into a cylindrical shape of m. Table 5 shows the results of Reference Example 2.
When cellulose fibers are used, the moisture content and peelability of the dehydrated cake are poor due to the hygroscopicity. Dehydration was not improved even when a polymer flocculant was used in combination. The pressure-molded pellets of Pete Moss could not be processed into the pressure-molded pellets without increasing the amount of the polymer flocculant. When the amount of the polymer flocculant was increased, the water content of the dehydrated cake was high and the peeling property was lowered.

[0018]

[Table 5]

Reference Example 3 A water-soluble organic polymer compound and a fibrous substance were added to and mixed with the sewage-mixed sludge of Reference Example 1, and an insolubilizer was added to dehydrate the sludge under the conditions of Reference Example 1. The water-soluble organic polymer compound is sodium alginate, and the fibrous substance is the peat moss of Reference Example 1,
Polyiron was used as the insolubilizer. Table 6 shows the results of Reference Example 3. By increasing the addition rate of peat moss, dehydration was possible without using an inorganic coagulant or a polymer coagulant.

[0020]

[Table 6]

Reference Example 4 To the sewage-mixed sludge of Reference Example 1, a water-soluble organic polymer compound of Reference Example 3, sodium alginate, and dry peat moss of a fibrous substance were mixed in advance in a powder state, and mixed.
Further, an insolubilizer was added and dehydration was performed under the conditions of Reference Example 1. Table 7 shows the results of Reference Example 4. Even if a mixture of dry peat moss and sodium alginate in a powder state was added to sludge, it did not become sufficiently compatible with sludge, so that the dehydration performance deteriorated.

[Table 7]

Reference Example 5 The sewage mixed sludge of Reference Example 1 was mixed with the dry peat moss of Reference Example 3 and sodium alginate in a powder state,
Water was added to the mixture to make it have a water content of about 30%, and the mixture was mixed. An insolubilizing agent was further added to dehydrate the mixture under the conditions of Reference Example 1. Table 8 shows the results of Reference Example 5.

[Table 8]

[0023]

INDUSTRIAL APPLICABILITY The present invention has the following effects by using a natural fiber hydrophilized with a water-soluble and biodegradable natural polymer agent as a dehydration aid. (1) The dehydration performance is improved without using an inorganic coagulant or a polymer coagulant. (2) The dehydrated cake can be used for compost in order to use a biodegradable and highly safe drug for dehydration. (3) The amount of waste can be reduced by promoting the composting of waste. (4) When the natural fiber of the dehydration aid remains in the compost, the air permeability of the soil is improved as a soil improving material.

Claims (3)

[Claims] 1. A thickness of several μm to 1 mm and a length of 1 mm to
A dehydration aid comprising 100 parts by weight of a few cm of natural fiber and 2 to 10 parts by weight of a water-soluble natural polymer drug. 2. The dehydration aid according to claim 1, wherein the natural fiber is a plant remains, and the water-soluble natural polymer agent is a salt of carboxymethyl cellulose, an alginate or polyvinyl alcohol. 3. A method for dehydrating liquid waste, which comprises adding and mixing the dehydration auxiliary agent according to claim 1 or 2 to liquid waste, and then performing dehydration treatment.