JPS5843300A - Assistant for dehydration of sludge - Google Patents

Abstract

PURPOSE:To improve the dehydrability of org. sludge produced by various kinds of waste water treatment markedly by preparing an assistant for dehydration of sludge by contg. >=1 kind of quaternary ammonium salts. CONSTITUTION:An assistant for dehydration s prepd. by contg. >=1 kind of the quaternary ammonium salts expressed by the formulaI(in the formula R1 denotes methyl groups and R2 alkyl groups or alkylene groups of 6-18C, R1 and R2 denote the same or different alkyl groups or alkylene groups of 6-8C and X denotes halogen, respectively). The compd. of said formulaIhas the characteristic that when the compd. is dissolved in a solid-liquid two phase system the hydrophilic groups direct toward the liquid phase and the hydrophohic groups expel water and direct toward the solid phase thereby orienting and adsorbing the same. Therefore the compd. of the formulaIprovides a marked dehydration effect toward sludge.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dewatering aid for organic sludge generated from the treatment of sewage, human waste, and various industrial wastewater.

Generally, organic sludge generated by biological wastewater treatment is
The bacteria, mold, protozoa, etc. that live there contain gelatin-like mucilage substances with high water-retention properties, or hydrophilic colloids made from gelatin-like substances, so dehydration can be carried out in that state. Dewatering aids such as soil, sawdust, fibers, and fly ash, or inorganic flocculants such as slaked lime and ferric chloride, are added to the sludge to adsorb or absorb the hydrophilic colloids and ids contained therein. A method has been used to increase the size of the membrane and reduce the filtration resistance. However, in these methods, the dehydration effect generally does not appear unless a large amount of dehydration aid or flocculant is added, and the use of these causes corrosion of the equipment, and furthermore, a large amount of ash is generated when the dehydrated cake is burned. '2fjt:::::Eniko Muf
,L&,9. .

At present, cationic polymer flocculants are widely used as dehydrating agents because they can produce flocs with large particle sizes in small amounts and can also reduce offshore resistance. However, the main action of polymer flocculants is crosslinking adsorption. For this reason, it is convenient to thicken the flocs and reduce offshore resistance, but water molecules bound to gelatin-like viscous substances are removed by adding 0.3 to 0.6% per SS weight to the mud. Even after centrifugal dehydration, 0.2-04% of SS weight remains.
Even if it is added and compressed and dehydrated, the water content of the resulting water cake is usually as high as 80 to 90%: yarn 1. , g)':□:':Mi The purpose of the present invention is to provide a dewatering aid that can eliminate the above-mentioned drawbacks of polymer flocculants and significantly improve the dewatering properties of organic sludge generated in various wastewater treatments. It's about doing.

[In the formula, R1 represents a methyl group, and R2 has 6 to 6 carbon atoms.
Represents 18 alkyl or alkylene groups,
or R1 and R2 have the same or different carbon atoms of 6 to
Examples of the 18 alkyl group or aralkynodi group include hexyl group, octyl group, □decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, coconut alkyl group, hardened tallow a4, kyl, and the like. □ Alkylene groups include hexenyl group, octenyl group,
Examples include decenyl group, octadecenyl group, octadecagenyl group, and the like.

... Chlorine, bromine, fluorine, and iodine are applicable as rogens, and chlorine or bromine is preferable.

The dehydration aid of the present invention may be present in the form of a single powder, an aqueous solution or a salt, and may contain a quaternary ammonium salt of the general formula (I) alone or as a mutual mixture of two or more. It can also be used as a mixture with known dehydration aids.

□The compound of general formula (I) is currently used as an antistatic agent in the textile industry, resin industry, etc.
It is effective as a dehydration aid for sludge, and has the property of being expelled, directed to the solid phase, and oriented and adsorbed. Due to this property, the compound of general formula (I) exhibits a remarkable dewatering effect on sludge, and in fact shows a significantly higher dewatering effect than that of conventional polymer flocculants.

Since the quaternary ammonium salt of the present invention has a long-chain hydrocarbon group as a hydrophobic group, its solubility in water is usually low. Therefore, when adding a quaternary ammonium salt to sludge, its craft point (
It is advantageous to heat the sludge to a temperature at or above the temperature at which the solubility of the quaternary ammonium salt used increases rapidly. The temperature of the sludge is generally 30-60°C, preferably 30-40°C. Processing times range from 1 to 60 minutes after reaching the craft point.

The sludge concentration used is high concentration and low concentration is 8000.
It is preferable to carry out the reaction at ~13,000 .mu./l.

Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Example I Excess sludge generated at the F City sewage treatment plant was treated using the natural sedimentation method.
Concentrate to 900 ■/l, and add octadecyltrimethylammonium chloride [C□8H37N (C
70 mg of powder 41' of H3) 3 Cl was added and reacted for 1 minute at 35-36°C. After the reaction, the sludge was left to stand until it reached room temperature, and 100 ml of it was passed through Nutsuchi xp [Okifu: Nai C17501B].

Suction pressure: -400 degrees Hg, elapsed time = 5 minutes], and 4.851 i' of dehydrated cake was obtained.

When the moisture content was measured according to the sewage test method, it was 68.1%. As a control, a sample without additives and a polymer flocculant [
0.5% by weight added to Brestall 444] When the moisture content of the added sample was measured, it was found that mud (SS: 139
0C+mJ/l) 11 Hexadecyltrimethylammonium bromite [C engineering. H33N(CH3)3Br
] was added, and the following operations were carried out in accordance with Example 1, yielding a dehydrated product with a content of 67.8%.

Example 3 Precipitated thickened sludge (S) collected from the F heavy sewage treatment plant mentioned above
S: 13900■7c>1t dioctadecyldimethylammonium chloride [(C.
'H3)2 NCt ] is the main component of Alucard 2H.
T-75 [Lion Co., Ltd. product, Zoost shape] 120
When 0 vq was added and the subsequent operation was carried out as in Example 1, a dehydrated cake with a water content of 69.3% was obtained.

Example 4 Surplus sludge (SS) generated from a certain food factory located in G City
Dodecyltrimethylammonium chloride CC12H25N(CH3)3c7 in 000cm/l) As described above, according to the present invention, a dehydrated cake with a moisture content of 65 to 70% can be obtained, and conventional dehydration aids such as slaked lime and chloride can be obtained. Compared to ferric iron and polymer flocculants, dehydration properties are greatly improved.

).

1

Claims (2)

[Claims] (1) General formula (I): [In the formula, R represents a methyl group, and R2 is a carbon number of 6 atoms.
~18 alkyl or alkylene groups, or R and R are the same or different and have 6 carbon atoms
~18 alkyl or alkylene groups;
A sludge dewatering aid characterized by containing one or more quaternary ammonium salts represented by the following formula: (2) The sludge dewatering aid according to claim 1, which is added to sludge heated to 3.0 to 40°C.