JPS59169593A - Waste water disposal - Google Patents

Abstract

PURPOSE:To remove an activator existent in waste water with the high efficiency of removal at a low cost for disposal, by mixing an inorganic salt, e.g. an Al, Fe, Ca or Mg salt, with waste water containing an anionic surfactant under an acidic condition, and froth separating formed composite matter. CONSTITUTION:Waste water 1 containing an anionic surfactant is mixed with an inorganic salt 3, e.g. an Al, Fe, Ca or Mg salt, under an acidic condition in a reaction tank 2. Hence, the inorganic salt 3 is hydrolyzed and reacted with the anionic surfactant to form flocks. During the formation of said flocks, suspended matter, wax, mineral oils, etc. are coagulatively flocculated, too. Then, the waste water from the reaction tank 2 is introduced into a froth disposal tank 4, wherein the flocks are let adhere to bubbles formed by the injection of air 7 through a sparger plate or pipe 6 provided therein. Said bubbles are broken during falling down, the flocks are reserved together with the foamed water 8 in a sludge tank 9, sludge 10 is accumulated on the foamed water 8, and water is drained as treated water 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating waste water generated from car washing and the like.

In general, car wash wastewater treatment equipment is designed to treat suspended solids, wax, and mineral oil.When discharging car wash wastewater, conventional treatment equipment can adequately handle the problem, but in order to reuse car wash wastewater, conventional If water recovery is increased in a treatment device, untreated substances will gradually accumulate and cause concentration disturbances, making it impossible to wash cars satisfactorily.

In addition, conventional treatment equipment is capable of treating anionic surfactants (hereinafter abbreviated as anionic surfactants), which are highly polluting substances in car wash wastewater.
The treatment performance is very low, and if the anionic activator is not treated to a few PPM, it may foam during the rinsing process (washing with water) of a car wash, or the wax liquid may become cloudy, making it very difficult to apply the wax. This will cause problems.

Currently, the following types of car wash wastewater treatment equipment are used:

(1) Oil adsorption treatment equipment can treat suspended solids and oils, but cannot treat anionic activators at all (2) Coagulation sedimentation equipment has an anionic activator removal rate of 40 to 60% (3) Aluminum electrolysis Treatment equipment performance is the same as (Yes), but no flocculant is required.

(4) Activated carbon adsorption device Although the removal rate of the anionic activator is 90% or more, it has the disadvantage that the processing cost is extremely high.

The object of the invention is to obtain an improved method for treating wastewater.

In the wastewater treatment method of the present invention, wastewater containing an anionic surfactant is mixed with inorganic salts such as aluminum, iron, calcium, and magnesium salts in an acidic state, and the inorganic salt and anionic surfactant are combined. The method is characterized in that a composite is produced and this composite is separated into foam.

Hereinafter, all embodiments of the wastewater treatment method of the present invention will be explained with reference to the drawings.

In the present invention, wastewater l containing an anion activator is mixed in a reaction tank 2 with inorganic salts 3 such as aluminum salts and iron salts. The inorganic salt 3 generates hydrochloric acid or sulfuric acid through hydrolysis to make the pH in the reaction tank 2 weakly acidic, and at the same time reacts with the anion activator in the reaction tank 2 to form a floracura property. During this floc formation, suspended solids, wax and mineral oil are also flocculated and flocculated.

The waste water from the reaction tank 2 is further introduced into a foam treatment tank 4, where the floc-containing water is foamed, flocs are attached to the foam generated by foaming with the unreacted anion activator, and the resultant water is discharged as treated water 5.

In this foam treatment tank 4, an air diffuser plate or pipe 6 is arranged inside, and air 7 is blown into it. The foam adhering to a large amount of the flocs breaks down while hanging down, and the flocs accumulate in the sludge tank 9 together with the foam water 8.

The sludge 10+″t floats on the foamy water 8 due to its hydrophobic nature.

In the present invention, a weakly acidic anionic activator treatment is adopted, but ABS (sodium alkylbenzene sulfonate), which is a typical anionic activator, and aluminum sulfate are treated with a 5 PH between 4.0 and 9.0. Table 1 shows the removal rate of the anionic activator in the case of reaction.

The inorganic salts used in Table 1 treatment agents include aluminum, iron, calcium, and magnesium. The salt is excellent. Liquid earth sulfate (LAS) is an aqueous solution of aluminum sulfate.
When added to wastewater, it produces sulfuric acid through its own hydrolysis, so it becomes weakly acidic even without adding acid to the wastewater.

Anionic activator sodium and amine are replaced with inorganic salts of aluminum, iron, calcium, and magnesium, thereby producing an anionic activator-inorganic salt composite floc as shown in the following formula.

6C12H25-■-8O3Na + A4 (So,
)3→2 (C+2 H2s-CriSOs)3 A
t+3Na2804 Table 1 shows that although there are many types of anion activators, the removal rate is high when flocculated at pH 4.5 to 5.5. The solubility of anionic activator flocs is minimal at weakly acidic conditions and increases as the pH increases. Conversely, when the pH becomes 4 or less, the anionic activator floc is concentrated in the raw QL.

In the past, the purpose of foam separation was to remove dissolved substances such as detergents, but in the present invention, a large amount of 70 pieces generated in the reaction tank 2 is separated into foam in a short time.

Generally, it is difficult to obtain extremely clear treated water by separating flocs into foam, and the amount of particles such as flocs caused by foam is pJ.
No. 11 applies a very KM rough interface phenomenon, and one important point is that the floc is more hydrophobic (hard to wet).

The hydrophobicity of the anionic activator floc changes with PI (PI), and when the generated anionic activator floc 'kPH' is treated with foam, the removal rate of the anionic activator is high.In weak acidity, the floc removal rate is over 95%, and in the case of medium Under strong and weakly alkaline conditions, the floc removal rate is less than 50%.

In addition to the pH, the size of the floc particles is important for the foam content M of 70 tsuku.If the flocs are sufficiently agglomerated, the foam can be completely separated from the flocs in a residence time of about 10 minutes.
Fine flocs that appear cloudy require a very long time (more than 30 minutes) to separate the foam. Further, in order to promote the reaction between the anion activator and the inorganic salt, it is necessary to stir the inside of the reaction tank using a highly efficient propeller 11 or the like.

Separation of anionic activator flocs is weakly acidic and roots with large particle sizes are easily separated, and 17. With a size of ~1/2, clear treated water that cannot be obtained by precipitation treatment can be obtained. The optimal ratio of air flow rate to processing flow rate (empty/liquid) is 'IA ~ 15/1; if the air flow rate is too low, foam cannot be discharged from the foam separation tank, and conversely, if it is too high, foam The amount of water increases, the water recovery rate decreases, and the empty/liquid ratio is from 7/1 to 10/10.
1, the percentage lost as foam water is less than 3 inches.

The foam separated by the method of the present invention has a very large amount of flocs attached to it, so that the foaming of the foam is appropriately suppressed, and it is not foam-breaking. No agent is required, most of the foam breaks while hanging down through the foam separation tank, and no foam overflows from the sludge tank.

In addition to the separation of flocs and unreacted anionic activator, foam separation includes separation of acid.

This acid is generated by hydrolysis of inorganic salts, but it can be removed to some extent by foam separation, and the pH of the foam-treated water is 0.6 to 1. It becomes higher by about θ. Therefore, when reusing treated water, Alka'J'fz is added to the foamed treated water.
No need to add.

When re-washing, the alkaline components in the tap water (well water) are consumed in the reaction tank, but car wash detergents contain alkaline components as auxiliaries (phosphates, sodium silicate, etc.). In the present invention, the pH of the reused water does not become strongly acidic even without adding alkali. 7 If inorganic salts are added so that the PHvf of the reaction tank is around -5, the treated water will always have a P
The flocs discharged by the method of the present invention, which can be maintained at H5, 6 to 6, are very hydrophobic and are therefore deposited floating in foamy water. Since sludge has a low moisture content, it can be scraped out and dried naturally, so it has a very easy-to-process sludge point.

The method of the invention can also be applied to other fields.

For example, if the wastewater contains an anionic activator, it can be applied to other than car wash wastewater without any problem. Further, in the case of wastewater suitable for coagulation sedimentation and coagulation pressure flotation treatment, the present invention can be applied even if the wastewater does not contain an anionic activator by using an aluminum flocculant and an inexpensive anionic activator in combination. If the present invention is applied, the floc separation tank will not be smaller than A, and since the floc removal is also foam separation, there is no need to discharge the sludge accumulated in the separation tank. A particular advantage is that the clarity of the treated water is so high that clarifying filtration is often not necessary.

Table 2 shows the processing performance according to the present invention.

[Brief explanation of drawings]

The figure is a Z-row sheet showing the wastewater treatment method of the present invention. 1... Drainage, 2... Reaction tank, 3... Inorganic salt, 4...
... Foam treatment tank, 5... Treated water, 6... Diffuser plate or pipe, 7... Air, 8... Foam water, 9... Sludge tank, 10... Sludge, 11 ···propeller.

Claims (1)

[Claims] Wastewater containing anionic surfactants is treated in acidic conditions.
A method for treating wastewater, which comprises mixing with inorganic salts such as aluminum, iron, calcium, and magnesium salts to form a composite of the inorganic salt and anionic surfactant, and separating this composite into foam.