JPH0671589B2 - Desizing wastewater treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention completely separates and recovers polyvinyl alcohol contained in wastewater treated with textile fabric from the viewpoint of physical, chemical and biological decomposition, and recovers COD load of wastewater. The present invention relates to a desizing wastewater treatment method for reducing pollution and preventing environmental pollution of natural marine rivers.

[0002]

2. Description of the Related Art In the textile industry, for example, when weaving, warp fibers are brought into close contact with each other to prevent fluffing on the surface and prevent yarn breakage due to friction to facilitate weaving. Polyvinyl alcohol (hereinafter referred to as PVA), carboxymethyl cellulose (hereinafter referred to as CMC), starch, oil agents (paraffin animal and vegetable oils, surfactants, etc.) are used as sizing agents. It is used.

With the recent increase in the speed of loom, P. V. The utilization rate of A is high and it is difficult to decompose P.A. V. The COD load due to A is large, the marine river is polluted, the dissolved oxygen is deficient, and the balance of the natural biological system is disturbed. Therefore, there are severe restrictions on the drainage of the wastewater.

[0004]

Therefore, in the industry, as a measure for wastewater regulation, conventionally, a boron chelate coagulation separation and recovery or a sludge treatment by a flotation or precipitation method using a flocculant of a high molecular weight organic compound and an inorganic compound has been adopted. However, problems remain with respect to the stability of the recovered material, the recovery efficiency, the treatment of sludge that occurs, and the like.

Therefore, the present inventor paid attention to this problem,
P. V. Along with improving the removal rate to nearly 100% regardless of the molecular weight of A, the P.A. V. As a method of oxidatively polymerizing A, coagulating it, and separating and recovering it, for example, Japanese Patent Application No. 2-127720 and Japanese Patent Application No. 2-1
We have filed applications for No. 77874 and Japanese Patent Application No. 3-46898.

That is, these prior inventions are mainly described in P.
V. As a means for recovering A. V. To the wastewater containing A, (1) peroxosulfate was added and heated to P. V.
The one that coagulates and collects A. (2) Add peroxosulfate and sulfuric acid and heat to P. V. The one that coagulates and collects A. (3) Add peroxosulfate and sulfuric acid and heat to P. V. After insolubilizing A, it is chelated with boron and separated and recovered. However, these prior art P.I. V. In the method of separating and recovering A, pure P.
V. Although the coagulation separation of A is relatively easy, the method of applying the warp sizing agent in a general woven factory is not uniform because each factory has a know-how.

For example, P. V. In addition to A.C. M. C, starch, an oil agent, a surfactant, and the like are used in combination, these combined substances include P. V. It interferes with the oxidative polymerization reaction of A and reduces the separation effect, and there is a problem that the prior art has no effect depending on the compounding condition of the sizing agent.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and is based on P. V. The purpose is to make A into a floc shape with high easiness and certainty of filtration separation in the insolubilized state.

That is, P. V. A, C. M. C. in starch dewatering wastewater containing C, starch, oil, and surfactant. V. A
By oxidative polymerization with peroxosulfate (peroxophosphate can be substituted). V. Although the hydrophilic group of A is sealed and separated and recovered, coexisting C.I. M. C, starch, oil agent, and surfactant are P.I. V. Since it interferes with the oxidative polymerization of A, the interfering substances must be prevented.

As the preventive agents, iron salts, aluminum salts and calcium salts are inorganic substances. In the organic matter, the polyelectrolyte effectively acts as an excellent coagulant, and P. V. A can be insolubilized and separated and recovered.

The desizing treatment of the fiber woven fabric is performed after the calcination treatment and before the scouring treatment in a hot water bath. By this hot water washing, the sizing of the fabric is V. A, C. M. C, oil, etc. are leached at 90% and starch at about 40%. This wash water is difficult to decompose C
The coagulant required for separation and recovery, which is the source of OD, is COD
Since it is not the molar ratio of the load but the liquid amount ratio, it is desirable to use as little water as possible.

The amount of water used for washing with hot water is 3 to 6 ton / Hr, although it varies depending on the type of processing speed fabric. The COD load of this wastewater is usually 16000PPM on average, and the P.O. V. The COD load occupied by A is about 10,000 PPM. The source of this hot water washing process is P.
V. COD at the time of total drainage by separating and removing A
Is reduced to around 50PPM, which is below the environmental standard.

The temperature during the hot water washing is 85 to 90 ° C.,
This wastewater is collected in a wastewater tank and aggregating agents such as iron sulfate, vantosulfate, calcium chloride and organic polymer electrolyte are added in an amount of 2-3 g /
1 (as inhibitors of PVA coagulation inhibitors) and P.V. V.
A 2-3 g / l of peroxosulfate was added as a coagulant, and the acid was added at 10 to 90 ° C. under conditions of pH 1.5 to 2
After reacting for 15 minutes, P. V. A undergoes polymerization due to the oxidative action of peroxosulfate, and P. V. The hydrophilicity of A is reduced and about 80% is separated. (If the amount of peroxosulfate added is excessive, oxidative polymerization will proceed too much, the hydrophilic groups will not be lost at all, and flocs will not form, making it difficult to separate solid-liquid from sand. Become).

Next, when the pH is adjusted to 4 to 5 with a strong alkaline agent such as caustic soda or caustic potash, the separated substances are bound to each other due to the salting-out effect to increase the flocs and reduce the viscosity (the amount of alkali added becomes excessive and the pH becomes too low. If it is 9 or more, it has an adverse effect and the particles become finer and become muddy, which makes separation by filtration difficult.

Next, 0.1 to 0.5 g / l of boric acid or borax is added.
Is added to P. V. The remaining hydroxyl group (OH) of A is chelated by boron, and P.A. V. A
The recovered substance, which becomes flocs and can be recovered 100%, is stable in pH and does not gelatinize even after long-term storage.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings.

Reference numeral 1 denotes a hot water washing treatment step of the cloth, which is contained in the liquid discharged from the hot water washing treatment step. V. The A concentration is measured by the concentration sensor (not shown). V. The amount of water is adjusted so that the A concentration is about 1.0 to 1.2%. The concentration of this discharged liquid is 85 to 90 ° C.
Is.

The above P. V. The effluent whose A concentration is adjusted to a desired value is supplied into the waste liquid receiving tank 2, and the effluent temperature is
Since the temperature is lowered to about 60 ° C. before being supplied to the waste liquid receiving tank 2, a heater 3 is installed in the waste liquid receiving tank 2 to discharge the waste liquid in the waste liquid receiving tank 2 again at 80 to 90 ° C. Heat to near.

The effluent reheated in the waste liquid receiving tank 2 is sent to the reaction tank 4, and in this reaction tank 4, an appropriate amount of coagulation supplied from the flocculant container 5, the oxidizer container 6 and the acid container 7 is fed. An agent, an oxidizing agent, and an acid are mixed in the drainage.

The mixed waste liquid in the reaction tank 4 is
During the course of sequentially passing through 9, the additives are sufficiently mixed with each other, and the additives are supplied into the neutralization chelate tank 10. An alkaline agent supplied from an alkali container 11 and borax supplied from a borax container 12 are added to and mixed with the drainage liquid in the neutralization chelate tank 10, and as a result, neutralization and chelation are performed to form a solid-liquid solution. Easy to separate flock P. V. A coagulate.

Next, the flocked P. V. The coagulation product of A. V. A coagulate and a filtrate are separated, and each P. V. A coagulate container 1
4 and the filtrate tank 15 are collected. As a result, P. V.
The effective recovery of A is extremely easy and reliable.

Experimental Example Desizing wastewater (PVA 1.2)
%, C.I. M. (Contains 0.83% of C, starch, oil, etc.)
250 g sulfuric acid band per 100 liters, p with sulfuric acid
After adjusting to H1.8, 200 g of ammonium persulfate was added and reacted at 94 ° C. for 10 to 15 minutes to remove P. V. A has a reduced hydrophilicity and is separated by about 80%. At this point, by adjusting the pH to 4.5 with a caustic soda, the P. V. A coagulate aggregates to reduce viscosity and increase flocs. Next, when 30 g of borax (10 hydrate) was added to this, the remaining hydrophilic groups were chelated and the flocs grew further, and P. V. A coagulate was obtained.

Next, as a result of investigating the degree of reduction of COD, it was as follows.

The COD 16000PPM of the desizing raw wastewater became 4640PPM by this treatment. 464 left
Since the load substance of 0 PPM can be easily treated by the conventional floating sedimentation activated sludge, the COD at the time of comprehensive drainage was 30 PPM.

P. V. A Comprehensive wastewater without separation treatment C
The OD is as high as 250 PPM, and the effectiveness in the desizing wastewater treatment method according to the present invention is clear.

[0026]

As described above, according to the present invention, the P. V. A, C.
M. The coagulant peroxosulfate is allowed to act on the desizing wastewater containing C, starch and oil under acidic conditions. V. After partially insolubilizing A, the pH is adjusted with an alkali, the floc is continued, the remaining hydrophilic groups are chelated with boron, and the flocs of the insolubilized product are re-grown. According to this, the P. V. The recovery of A is extremely easy and reliable, and a highly efficient P.A. V. The effect that A recovery is realized is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus for carrying out the desizing wastewater treatment method of the present invention.

[Explanation of symbols]

1 ... Hot water washing process 2 ... Waste liquid receiving tank 3 ... Heating means 4 ... Reaction tank 5 ... Flocculant container 6 ... Oxidizer container 7 ... Acid container 8 ... Reaction tank 9 ... Reaction tank 10 ... Neutralizing chelate tank 11 ... Alkali container 12 ... Borax container 13 ... Filter 14 ... P. V. A coagulate 15 ... filtrate

Claims (1)

[Claims] 1. A coagulant and an oxidizing agent are added to a desizing wastewater containing polyvinyl alcohol, carboxymethyl cellulose, starch, an oil agent and the like to obtain a pH of 1.
After adjusting to 5-2 and heating, the primary coagulation of polyvinyl alcohol in the wastewater is performed, and then the pH is adjusted to 4 to 5 with alkali to carry out the secondary coagulation, and the remaining hydrophilic groups are chelated with boron to coagulate. A desizing wastewater treatment method, characterized in that a floc suitable for filtering is used.