JPS61204100A - Dehydrating method for sludge - Google Patents

Abstract

PURPOSE:To perform satisfactory dehydration even of org. sludge which is not easily dehydrated and to obtain dehydrated cake having low water content by treating org. sludge by adding a cationic surface active agent, an anionically modified natural polymer, and an org. polymer flocculant. CONSTITUTION:At least one cationic surface active agent such as alkylamine salt, alkyl quat. ammonium salt, alkyl isoquinolinium salt, alkyl picolinium salt, alkyl pyridinium salt, alkyl imidazolinium salt, alkyl dimethyl benzyl ammonium salt, alkylamido methyl pyridinium salt, alkyl oxymethyl pyridinium salt, polyoxyethylene alkylamine, anionically modified natural polymer such as vegetable polymer mucilage, animal protein, fermented mucilage, starch, cellulose, an org. polymer flocculant, are added to org. sludge to treat the org. sludge. As a result, org. sludge which is not easily dehydrated conventionally can be dehydrated effectively.

Description

[Detailed description of the invention] "Purpose of invention" @Industrial application field.

The present invention relates to an efficient method for dewatering organic sludge generated in the treatment of water and sewage systems, industrial wastewater, human waste, etc., particularly organic sludge that contains microorganisms and is difficult to dehydrate.

1 Conventional technology.

Conventionally, to treat organic sludge as described above, a method was generally used in which only an organic polymer nesting agent was added to the sludge, and in particular, when a cationic polymer flocculant was used for organic sludge containing microorganisms. Furthermore, it is common practice to use an anionic polymer flocculant with the opposite charge. This method has a good sludge flocculation effect and can form large flocs, but on the other hand,
Because sludge with polymer flocculant attached becomes hydrophilic, it is not possible to significantly reduce the water content of sludge;
Vacuum Pi! i. When dewatering is performed by a dewatering method using a furnace cloth such as belt press filtration, the sludge has poor releasability from the IP cloth and reduces dewatering efficiency. In other words, organic polymer flocculants bind to sludge mainly through crosslinking adsorption, so even if a cationic polymer flocculant and an anionic polymer flocculant with the opposite charge are used together to create a filamentous coagulated substance, the sludge It is difficult to actively modify the surface of the metal. In such cases, inorganic dewatering aids such as diatomaceous earth or clay are added to the sludge to improve its dewatering properties.

Generally, dehydration treatment is carried out by adding an inorganic flocculant such as slaked lime or iron chloride, or by using a combination of these polymer flocculants. However, these inorganic dehydration aids and inorganic flocculants need to be added in large amounts, 10 to 100 weight units per sludge solid content, and almost all of this becomes part of the coolant after treatment. The weight and volume of the whole cake increases, and the combustibility of this cake is extremely poor, which increases the incineration cost. In addition, there are undesirable problems such as corrosion of sludge treatment equipment and incineration equipment, and accumulation of scale. There were many. On the other hand, cationic surfactants have been used alone, but cationic surfactants separate bound water adhering to the surface of sludge particles, making them easier to dehydrate, so they have good dewatering properties. However, sludge flocs do not grow large due to poor cohesiveness.
The sludge, which forms fine flocs and has extremely low thickening properties, is put into a dewatering device and dehydrated by means such as natural pressure, so the dewatering efficiency was not necessarily good. In addition, excess cationic surfactant that has not reacted with the sludge flows into the wastewater treatment system in a free state, which has a negative impact on the treatment mechanism, and especially in the case of biological treatment such as activated sludge treatment, living organisms may be drastically reduced. There were drawbacks such as the possibility of death.

An object of the present invention is to provide an efficient sludge dewatering method that eliminates the above-mentioned drawbacks.

"Structure of the invention" 1. A means to solve a problem.

As a result of intensive research, the inventors of the present invention have developed an efficient sludge crossbar that eliminates the above-mentioned drawbacks as described below.In a method for treating organic sludge with a flocculant and dewatering it, the present inventors have developed a method for treating organic sludge with a flocculant and dewatering it. Alkyl quaternary ammonium salt, alkylisoquinolium salt, alkylpicolinium salt, alkylpyridinium salt, alkylimidazolinium salt, alkyldimethylbenzylammonium salt, alkylamidomethylpyridinium salt, alkyloxymethylpyridinium salt, One or more cationic surfactants such as polyoxyethylene almulamine, anionic modified products of natural polymer substances such as vegetable polymer mucilage, animal protein, starch and cellulose, and organic polymer aggregates. The dewatering properties of cationic surfactants and the properties of anion-modified natural polymers that have opposite ions and participate in neutralization and production of coagulation substances , by skillfully combining the strong flocculating properties of organic polymer flocculants to form sludge flocs with low water content and large hydrophobicity, resulting in extremely good dewatering efficiency, organic sludge particles, and microorganisms in the sludge. Organic sludge particles are generally negatively charged;
In addition, there is a hydrophilic colloid-like viscous substance generated by microorganisms on the surface of the sludge particles, and water molecules are tightly bound to this viscous substance, making it extremely difficult to dehydrate. When one or more activators react, their hydrophobic groups are oriented toward the bound water, separating and expelling the bound water, and the hydrophobic groups, including those in the sludge particles, bond to each other, forming a dense skeleton between the sludge particles. The 11i structure combines and aggregates to form 70 pieces that are easy to dehydrate, but they are fine and lack condensation, so the dehydration efficiency is not necessarily good, and they are positively charged.

The anion-modified natural polymer reacts with this, neutralizing it and producing a coagulated substance, which adheres to the surface of the sludge and modifies the sludge. Furthermore, the polymer flocculant reacts with it and causes strong flocculation. As the progress progresses, the sludge flocs grow larger and become harder.
It becomes extremely easy to dehydrate. A polymer flocculant is first added to organic sludge to flocculate the sludge particles, and the sludge particles are concentrated in a casing or on a screen, and then a cationic surfactant and an anion modified natural polymer substance are added. The flocs produced in this case tend to have a slightly larger shape and a slightly softer hardness than the former under the same conditions. As a polymer l# aggregator, a cationic surfactant and an anion modified product of a natural polymer substance are first added to 7J
If the sludge is generally neutralized, then 7JO
There is no problem in using anionic or cationic polymer flocculants, a combination of both, or nonionic polymer flocculants, but chronic sludge as described above has a complex composition and unstable properties, so cationic surfactants and natural polymers are used. Eripolymer flocculants are preferably selected based on the properties of the sludge after adding the anion-modified substance. If a polymer flocculant is added first, a cationic polymer flocculant is often suitable since organic sludge is generally negatively charged, but it is preferable to select an appropriate one depending on the properties of the sludge immediately before addition. . However, this is not guaranteed. Furthermore, it is also possible to add a cationic surfactant and an organic polymer flocculant at the same time. In this case, the processing operation is complicated and the flocs produced tend to be somewhat unstable.

The cationic surfactants used in the present invention are as follows.

The argylamine salt is a primary amine halide represented by the general formula (1), a secondary amine halide represented by the general formula (2), and a tertiary amine halide represented by the general formula (warm), each singly or as a mixture.

General formula <11-・-(R-NH,)"!-General formula (2)
--('H', >NH2)" x-alkyl 4th
The class ammonium salt is a quaternary ammonium halide represented by the general formula (4) alone or as a mixture. The alkylisoquinolium salt is a single substance or a mixture of aJ%/xF alkylisoquinolium halides represented by the general formula (5).

The alkyl vicolinium salt is a single substance or a mixture of argylpicolinium halides represented by the general formula (6).

The algylbyridinium salt is a mixture of the single algylbyridinium halide represented by the general formula (7).

The alkylimidazolinium salt is a single substance or a mixture of alkylimidazolinium halides represented by the general formula (8).

Alkyldimethylbenzylammonium salt B general formula (9
) is a single substance or a mixture of alkyldimethylbenzylammonium oxides represented by:

The alkylamidomethylpyridinium salt is a single substance or a mixture of alkylamidomethylpyridinium halides represented by the general formula (1).

The alkyloxymethylpyridinium salt has the general formula (11)
It is a single substance or a mixture of dimethylpyridinium halides in an alkyl group represented by:

Polyoxyethylene alkylamine is a single substance or a mixture of WR compounds represented by the general formula (121).

In the above general formulas (1) to (12), R-R4 represents an alkyl group, and the alkyl group may be a straight chain or a branched chain, and the alkyl group may be a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group. , heptyl group.

Mixed alkyls derived from animal and vegetable oils, including those having 1 to 18 carbon atoms, such as octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, etc. The group may be, for example, a coconut argyl group.

Or represents a halogen atom such as fluorine, chlorine, bromine, iodine, etc.

The cationic surfactant can be used in the form of a liquid paste or a powder, and among these, the liquid form is mainly used because it is easier to use.

The solution is preferably an aqueous solution, but those that are insoluble in water can be dissolved with a water-soluble organic solvent such as alcohol.

Examples of anion-modified natural polymer substances used in the present invention are as follows.

Natural polymeric substances, semi-synthetic polymeric substances made of these, or derivatives thereof are anionically modified products, and the anionic groups include carboxy A, group (-000E
t), sul * y if, (-803H), sulfate ester group (-0805H), phosphate ester group (-0PO(
oH) 2) and their metal salts are suitable, and natural polymeric substances include Fi starch, seaweed, plant mucilage (gum arabic, gum tragancoa, troloaloy, soybean), animal protein (casein, gelatin, egg white, plasma protein), There are fermented mucilages (pullulan, dextra/), and starchy semi-synthetic polymer substances (soluble starch, carboxy starch, pritish gum, dialdehyde starch, textrin).

There are celluloses (viscose, methylcellulose, ethylcellulose, carboxycellulose, hydroxyethylcellulose).

The organic molecular coach used in the present invention is an anion agent, as an anion agent, acrylic acid hypertrophy metal salt, acrylic amide acrylic co -polymer, acrylua) 1- methacrylic acid N as a cationic polymer flocculant.
-111-Dialkylaminoalkyl ester-acrylamide copolymer, polymethacrylic acid dialkylaminoalkyl ester, polymethacrylic acid trialkylammonioethyl salt, polymethacrylic acid sialkyl monobenzyl ammonioethyl salt, and the number of carbon atoms in the alkyl group is 1
Examples of nonionic polymer flocculants include nonionic polyacrylamide, polyethylene oxide, and polyvinyl alcohol.

1 action.

When a cationic surfactant is added to one-loss sludge, the hydrophobic groups of the cationic surfactant reject and expel the bound water of the colloidal viscous substance on the surface of the sludge, and the hydrophilic groups move toward the solid phase of the sludge, and the hydrophilic groups move into the liquid phase. The sludge binds to the sludge particles, causing the sludge to coagulate, become easily dehydrated, and become positively charged. The anion-modified natural polymer reacts with this and neutralizes it, and a coagulated product is formed and adheres to the surface of the sludge.

However, the sludge particles are very fine. Furthermore, when an organic polymer flocculant is added, it reacts with the organic polymer flocculant, and the fine sludge particles easily aggregate to form a particle group. Due to the action, it becomes a large and hard flock.

Since this material is crushed and the bound water is separated, it is easily dehydrated under pressure. When an organic polymer flocculant is added first, the sludge particles are first subjected to strong #nesting action to form large flocs, then bound water is separated by the action of the cationic surfactant, and further anions of the natural polymer substance are added. The denatured product is neutralized and the generated coagulated material adheres to the surface of the sludge. In this case, the flocs become larger, but some bound water may remain in the aggregated particles.

"Effects of the Invention" As described above, the sludge dewatering method of the present invention uses a cationic surfactant to separate the bound water of colloidal substances from organic sludge, which is difficult to dewater due to colloidal substances attached to the surface. It is expelled, neutralized with an anion-modified natural polymer substance, and the coagulated material is attached to the surface to make it easy to dehydrate.

This is coagulated using an organic polymer flocculant to make it large and hard.
Since it is a method of forming a 0-piece and dewatering by applying pressure, etc., the dewatering efficiency is extremely high, and even organic sludge, which is difficult to dehydrate, can be dehydrated well and a cake with a low water content can be obtained, and F cloth is used. When dewatering the sludge, the sludge does not leak or block the weave of the furnace cloth, and the cationic surfactant is neutralized and reacts to form a coagulate, so wastewater can be treated in a free state. It does not flow into the system, therefore it does not disturb the processing mechanism and has excellent effects.

Example 1 Low-diluted two-stage aerated surplus sludge (fixed content concentration 2.4% PH6.5) generated at the human waste treatment plant in City B was first treated with coconut alkyldimethylaquine hydrochloride, which is a cationic surfactant.
The bound water is separated from the colloidal substances on the surface of the sludge particles, and then sodium alginate, dicarboxylic acid starch, and carboxymethyl cellulose, which are anion-modified natural polymer substances, are added separately to neutralize, react, and finally Polymethacrylic acid diaminoalkyl ester, which is a cationic polymer flocculant, was added to the sludge to cause flocculation, and the flocculated sludge was dehydrated using a belt press dehydrator to obtain the results shown in Table 1.

The comparisons are larger: the conventional method in which only a polymer flocculant is added, the method in which an anionic modified natural polymer substance and a cationic polymer flocculant are used in combination, and the running method in which only a cationic surfactant is added. Shows the processing results.

As is clear from Table 1, the sludge dewatering method of the present invention is superior to conventional methods in terms of dewatering performance, treatment capacity, and cake removal performance.

Example 2 Activated surplus sludge (solid content concentration 1) generated at a municipal slaughterhouse
．． 6%P! 46.0) K First, methacrylic acid N-1, which is a cationic polymer flocculant? 'Dialkylaminoalkyl ester/acrylamide copolymer is added in the proportions shown in Table 2 to form flocs, which are concentrated using a screen to form flocculated sludge. Chloride and polyoxyethylene tallow alkylamine are added separately in the proportions shown in Table 2 to separate the bound water from the colloidal substances on the surface of the sludge particles, and then each is added to the anionic semi-synthetic polymer carboxymethane. Cellulose was added to neutralize the mixture to form a coagulated material, which was dehydrated using a belt press dehydrator to obtain the results shown in Table 2.

For comparison, the results of a conventional method in which only the cationic polymer flocculant was added and a method in which this was combined with an anionic polymer flocculant, an acrylamide-acrylic acid copolymer, are shown.

As is clear from Table 2, the present fm@mei sludge dewatering method is superior to the conventional method in terms of dewatering performance, treatment capacity, and cake removal performance.

Claims (6)

[Claims] (1) In a method of treating organic sludge with a flocculant and dehydrating it, an alkylamine salt, an alkyl quaternary ammonium salt, an alkylisoquinolium salt, an alkylpicolinium salt, an alkylpyridinium salt, an alkylimidazolinium salt, One or more cationic surfactants such as alkyldimethylbenzine ammonium salts, alkylamidomethylpyridinium salts, alkyloxymethylpyridinium salts, and polyoxyethylenealkylamines, vegetable polymer mucilage, animal protein, fermented viscous 1. A method for dewatering sludge, which comprises adding an anion-modified product of a natural polymer substance such as sludge, starch, or cellulose and an organic polymer flocculant to organic sludge for treatment. (2) First, a cationic surfactant is added to organic sludge and reacted, then an anion modified natural polymer substance is added and mixed, and an organic polymer flocculant is further added to cause coagulation and concentration. A method for dewatering sludge as described in scope item (1). (3) The sludge dewatering method according to claim (2), wherein the organic polymer flocculant is a cationic polymer flocculant. (4) The method for dewatering sludge according to claim (2), wherein the organic polymer flocculant is an anionic polymer flocculant. (5) A patent claim characterized in that first an organic polymer flocculant is added to organic sludge for flocculation concentration, then a cationic surfactant is mixed, and an anion modified product of a natural polymer substance is further added. A method for dewatering sludge as described in scope item (1). (6) The method for dewatering sludge according to claim (5), wherein the organic polymer flocculant is a cationic polymer flocculant.