Organic sludge dewatering auxiliary

Abstract

To provide an organic sludge dewatering auxiliary that can help achieve good dewaterability.SOLUTION: The organic sludge dewatering auxiliary of the present invention contains a cellulose material with a copper value greater than 1.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an organic sludge dewatering aid.

Background Art

[0002] When treating sludge discharged from factories, agricultural facilities, households, etc., a dewatering aid for enhancing the dewatering efficiency has been used together with a flocculant (dewatering agent). Patent Document 1 describes that by using pulp having a streaming potential value of -85 mV or more and -58 mV or less, a weight average fiber length of 0.5 mm or more and 5.0 mm or less, 3σ when the standard deviation of the weight average fiber length is σ of 1 mm or more and 5 mm, and a copper number of 0.05 or more and 0.75 or less, the dewatering efficiency can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in order to reduce the water content of the sludge, it is desirable to set the pressure during dewatering as high as possible. However, when the pressure is increased during dewatering using the dewatering aid described in Patent Document 1, it is expected that the pulp will be crushed and it will be difficult to exhibit the dewatering function. An object of the present invention is to provide an organic sludge dewatering aid capable of exhibiting good dewatering performance.

Means for Solving the Problems

[0005] The present invention provides the following [1] to [4]. [1] An organic sludge dewatering aid containing a cellulose material having a copper number exceeding 1. [2] The organic sludge dewatering aid according to [1], wherein the cellulose material is pulp. The organic sludge dewatering aid according to [2], wherein the pulp is unbleached pulp. The organic sludge dewatering aid according to [2] or [3], wherein the pulp is softwood or hardwood pulp.

Advantages of the Invention

[0006] According to the present invention, an organic sludge dewatering aid having good dewatering performance is provided and can be used for treating various sludges.

Modes for Carrying Out the Invention

[0007] [1. Organic Sludge Dewatering Aid] The organic sludge dewatering aid contains a cellulose material as an active ingredient. The cellulose material is a material mainly composed of cellulose.

[0008] [1.1 Cellulose Raw Material] The cellulose contained in the cellulose material is derived from a cellulose raw material which is the raw material of the cellulose material. The cellulose raw material is usually wood, which may be any of hardwood, softwood, or a combination of two or more of these. Examples of softwood include, for example, Cryptomeria (e.g., sugi), Abies (e.g., fir), Larix (e.g., larch, western larch, tamarack), Pinus (e.g., black pine, dwarf pine, radiata pine, eastern white pine), Chamaecyparis (e.g., hinoki cypress, chamaecyparis, Lawson cypress), Pseudotsuga (e.g., Douglas-fir), Tsuga (e.g., hemlock), Thuja (e.g., arborvitae), Taxus (e.g., yew), and plants of the genus Picea (e.g., spruce). Among them, plants of the genus Cryptomeria, Pinus, Larix, and Chamaecyparis are preferred. Examples of hardwood include, for example, Fagus (e.g., beech), Cercidiphyllum (e.g., katsura tree), Acer (e.g., maple, field maple), Populus (e.g., poplar), Eucalyptus (e.g., eucalyptus), Acacia (e.g., acacia), Quercus (e.g., oak, Japanese evergreen oak, oak, sawtooth oak), Liquidambar (e.g., sweetgum), Celtis (e.g., hackberry), Zelkova (e.g., zelkova), Paulownia (e.g., paulownia), Salix (e.g., willow), Diospyros (e.g., persimmon), Styrax (e.g., Japanese snowbell), and plants of the genus Aucuba. Among them, plants of the genus Eucalyptus are preferred. On the other hand, the cellulose raw material may be non-wood, for example, bamboo, hemp, jute, kenaf, agricultural waste, paper (e.g., waste paper, printing paper). The cellulose raw material is preferably wood (hardwood, softwood), and more preferably softwood.

[0009] [1.2 Lignin] The cellulose material usually contains lignin as a component other than cellulose. The amount of lignin can be expressed by the copper number.

[0010] -Copper value- The cellulose material preferably has a copper value exceeding 1, preferably 5 or more, 7 or more, or 8 or more, more preferably 10 or more. As a result, since lignin remains and has rigidity, good dehydration performance can be exhibited even when used at a high dehydration pressure. The upper limit is usually 120 or less, preferably 100 or less, more preferably 80 or less. The copper value can be measured in accordance with JIS P 8211:2011.

[0011] The lignin content of the cellulose material can be adjusted, for example, by the type of cellulose raw material, the conditions of the delignification treatment, and the like.

[0012] [1.3 Optional components] The cellulose material may contain components other than cellulose and lignin. For example, components other than cellulose derived from the cellulose raw material, by-products in the manufacturing process, and any additives (such as preservatives, additives used in pulp and paper manufacturing, etc.) can be mentioned. Examples of components derived from the cellulose raw material include monosaccharides (e.g., trioses such as aldotriose and ketotriose; tetroses such as erythrose, threose, and erythrulose; pentoses such as xylose, ribose, arabinose, lyxose, ribulose, and xylulose; hexoses such as mannose, allose, altrose, glucose, gulose, idose, galactose, talose, psicose, fructose, sorbose, tagatose, fucose, fructose, and rhamnose; heptoses such as sedoheptulose), oligosaccharides (e.g., disaccharides such as sucrose, lactose, maltose, trehalose, turanose, and cellobiose; trisaccharides such as raffinose, melezitose, and maltotriose; tetrasaccharides such as acarbose and stachyose; oligosaccharides such as xylooligosaccharide, cellooligosaccharide, fructooligosaccharide, galactooligosaccharide, and mannanooligosaccharide), polysaccharides (e.g., glycogen, starch (amylose, amylopectin), cellulose, hemicellulose, dextrin, glucan), reducing sugars, and sugar-modified products. Examples of by-products include sodium sulfate, sodium sulfite, sodium chloride, magnesium sulfate, magnesium sulfite, magnesium chloride, calcium sulfate, calcium sulfite, calcium chloride, ammonium sulfate, ammonium sulfite, ammonium chloride, sodium hydroxide, and inorganic fillers and pigments such as calcium carbonate and kaolin for coated and uncoated paper.

[0013] Since the amounts of the above optional components vary depending on the type of cellulose raw material, manufacturing conditions, etc., it is difficult to define them uniquely, but it is preferably a small amount, for example, 10% by weight or less, 8% by weight or less, 5% by weight or less, 1% by weight or less, 0.1% by weight or less, or 0.01% by weight or less, preferably below the detection limit, and more preferably 0% by weight.

[0014] [1.4 Moisture Content] The cellulose material may contain moisture. The moisture content is usually 40% by weight or more, preferably 45% by weight or more, more preferably 50% by weight or more. The upper limit is usually 90% by weight or less, preferably 85% by weight or less, more preferably 80% by weight or less, 75% by weight or less, 70% by weight or less.

[0015] [1.5 Examples of Cellulose Materials] Examples of the cellulose material include, for example, pulp.

[0016] - Pulp - Pulp is manufactured by pulping the above cellulose raw materials, and the manufacturing conditions or methods may include the process of pulping the above wood chips and are not particularly limited. Examples of pulping methods include chemical methods (chemical pulp) such as kraft method, sulfite method, soda method, polysulfide method, etc. that perform digestion, mechanical methods (mechanical pulp) using equipment such as refiners and grinders; methods of pulping by mechanical force after pretreatment with chemicals (semichemical pulp), etc. Although pulping methods generally used in the paper industry are mentioned, it is not limited to these. Further, treatments such as beating may be performed. The obtained pulp may be any of unbleached pulp, beaten pulp, and unbeaten pulp. Examples of chemical pulp include sulfite pulp and kraft pulp. Pulp is classified into softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), dissolving kraft pulp (DKP), hardwood unbleached sulfite pulp (LUSP), hardwood bleached sulfite pulp (LBSP), hardwood oxygen delignified kraft pulp (LOKP), softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp sheet (NBKP), softwood unbleached sulfite pulp (NUSP), softwood oxygen delignified kraft pulp (NOKP), and recycled pulp according to the treatment in the process. Also, mechanical pulp is classified into types such as groundwood pulp (GP), pressurized groundwood pulp (PGW), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), and alkaline hydrogen peroxide thermomechanical pulp (APTMP) according to the manufacturing method. Among these, chemical pulps such as kraft pulp and sulfite pulp are preferred, chemical pulp derived from softwood is more preferred, and unbleached pulp derived from softwood is more preferred. Unbleached pulp has less damage due to bleaching, is excellent in strength, and has relatively high resistance to high pressure compared to bleached pulp.

[0017] [1.6 Physical properties of cellulose materials] The cellulose material preferably exhibits the following physical properties. -Whiteness- The whiteness of the cellulose material is preferably 70% or less, more preferably 60% or less, still more preferably 55% or less. The lower limit is not particularly limited, but for example, it is 10% or more, 20% or more. In this specification, the whiteness can be measured in accordance with ISO 2470-1:2016.

[0018] [1.7 Method for producing cellulose material] The cellulose material can be produced from the above-mentioned cellulose raw materials. For example, when the cellulose material is pulp and its processed products, it can be produced by subjecting the cellulose raw materials to treatments such as cooking.

[0019] - Chip - When the cellulose raw material is wood, it is usually first processed into wood chips. Examples of the method for producing wood chips include, for example, after harvesting plants, removing the bark from the wood parts (trunk and branches) and cutting or crushing them.

[0020] - Cooking treatment - The chips are subsequently subjected to a cooking treatment. Examples of the cooking method include, for example, the soda cooking method, the kraft cooking method, the organosolv cooking method, the polysulfide cooking method, and modified methods thereof. The soda cooking method and the kraft cooking method are preferred. After cooking, usually, neutralization, washing, dewatering, and drying treatments are carried out.

[0021] - Delignification treatment - The pulp after cooking may undergo a delignification treatment. Examples of the delignification treatment include, for example, an oxygen delignification treatment. The oxygen delignification treatment is a process of ionizing lignin in an alkaline atmosphere to generate a large amount of phenolic hydroxyl groups and reacting them with oxygen molecules. Thereby, lignin can be depolymerized and dissolved in alkali.

[0022] - Grinding treatment - The pulp after digestion may be subjected to a pulverization treatment as necessary. The pulverization treatment can be performed using a pulverizer. Examples of the pulverizer include a cutting mill, an impact mill, a pneumatic mill, a hammer mill, a roll mill, a roller mill, a media mill, a media agitation mill, and a freeze pulverizer, and they may be used alone or in combination of two or more kinds.

[0023] [4. Organic Sludge Dewatering Aid and Method of Using the Same] The cellulose material can absorb the liquid components of the sludge by contacting the sludge, and can be used for improving the efficiency of the dewatering treatment using a flocculant (dewatering agent), so it is useful as an organic sludge dewatering aid.

[0024] Examples of the target sludge include organic sludge. Organic sludge is sludge containing organic substances, and examples thereof include activated sludge from domestic wastewater, sludge containing livestock excrement, activated sludge from food factories, and activated sludge of organic chemical substances. The discharge destination is not particularly limited, and examples include sewage treatment plants, factories (food factories, chemical factories), and agricultural and livestock facilities.

[0025] The addition amount of the cellulose material to the sludge is usually 0.05% by weight or more, preferably 0.1% by weight or more, more preferably 0.2% by weight or more, and still more preferably 0.3% by weight or more, based on 100% by weight of the sludge. The upper limit is not particularly limited, but is usually 3% by weight or less, preferably 2% by weight or less, and more preferably 1% by weight or less.

[0026] In sludge treatment, usually, a flocculant (dewatering agent) is added to the sludge together with an organic sludge dewatering aid. Examples of the flocculant include organic flocculants such as polymer flocculants of anionic, cationic, nonionic types, etc.; inorganic flocculants such as aluminum-based flocculants and iron-based flocculants. Examples of the nonionic polymer flocculant include polyacrylamide, polyethylene oxide, and urea-formalin resin. Examples of the cationic synthetic polymer flocculant include acrylic cationic polymers such as polyaminomethylacrylamide, polyvinylimidazoline, chitosan, ionene copolymers, and epoxyamine copolymers. Examples of the amphoteric synthetic polymer flocculant include lecithin-based amphoteric surfactants and casein degradation product-based amphoteric surfactants. Examples of the aluminum-based flocculant include aluminum sulfate (aluminum band) and polyaluminum chloride (PAC). Examples of the iron-based flocculant include ferric chloride, polyferric sulfate, and polysilicate iron. Among these, organic flocculants are preferred. The addition amount of the flocculant can be appropriately selected according to its type.

[0027] The organic sludge dewatering aid may further contain any additive. The additive may be any component commonly used in the dewatering aid, and examples include additives such as a base, a carrier, a solvent, a dispersant, an emulsifier, a buffer, a stabilizer, an excipient, a binder, a disintegrant, a lubricant, a thickener, a humectant, a coloring agent, a fragrance, and a chelating agent. Also, when the additives added during pulp and paper manufacturing are contained in the cellulose material, these additives may also be used.

Examples

[0028] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

[0029] Examples 1 to 2 To 400 mL of surplus sludge from a pig farm wastewater treatment facility (TS (solid) concentration: 1.08%, pH: 6.79, appearance: blackish brown, odor: nitrification odor), each pulp sample shown in Table 1 (0.3% of the sludge volume) and a flocculant (0.2% aqueous solution of an acrylic cationic polymer, 5% of the sludge volume) were added to form flocs. This was put into a testing machine (manufactured by Reserver, pressure area 81 cm 2 , pressure and holding time variable type), and dehydration treatment was carried out at a pressure of 360 kPa for 3 minutes (assuming a screw press dehydrator). The water content of the cake was measured using a moisture meter (manufactured by Kett, infrared moisture meter FD-720), and the solid recovery rate was calculated (Table 1). Note that for the cake water content, the lower the value, the higher the dehydration performance is judged, and for the solid recovery rate, the higher the value, the higher the dehydration performance is judged.

[0030]

Table 1

[0031] Examples 1 to 2 both showed good dehydration performance. Among them, Examples 1 and 3 (softwood pulp) showed a lower cake water content and a higher solid recovery rate.

[0032] Examples 3 to 4 Except for using each sample (ground product) shown in Table 2, floc preparation and dehydration treatment were carried out in the same manner as in Example 1, and the cake water content and solid recovery rate were measured (Table 2).

[0033]

Table 2

[0034] Examples 3 and 4 both showed good dehydration performance. Example 3 showed a decrease and an increase in both the cake water content and the solid recovery rate compared to Example 1 corresponding to the unground sample.

[0035] The results of the above examples show that the organic sludge dehydration aid of the present invention can fully exhibit its dehydration function even when the dehydration pressure is high and has good dehydration performance.

Claims

1. An organic sludge dewatering aid containing a cellulose material with a copper value exceeding 1.

2. The organic sludge dewatering aid according to Claim 1, wherein the cellulose material is pulp.

3. The organic sludge dewatering aid according to Claim 2, wherein the pulp is unbleached pulp.

4. The organic sludge dewatering aid according to Claim 2 or 3, wherein the pulp is softwood or hardwood pulp.

Images