JPS59186696A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To make waste water contg. an excessive org. high polymer flocculating agent non-pollutive by adding a mineral acid to the waste water contg. the org. high polymer flocculating agent to adjust the pH to <=7 and bringing ozone into gas-liquid contact with the waste water for <=10min at a ratio of 1-5wt%. CONSTITUTION:The waste water A contg. an org. high polymer flocculating agent is conducted to a pH adjusting tank 7, where a mineral acid such as a sulfuric acid is added thereto to make the acidic waste water A1 having <=7pH which is then conducted into an aerating tank 1 provided with a diffuser 5 and while the waste water is aerated for a specified time, the water is stagnated therein. The oxygen D from an oxygen feeder 2 is passed through an ozone generator 3 and the resultant ozone E is released from the diffuser 5 by a fan 4 and is brought into contact with the waste water A1 during the stagnation. The water is released as treated water C after the stagnation for a specified time. The waste gas B from the tank 1 is decomposed by a waste gas treating device 6 and is released into the atmosphere. Pure oxygen or dehumidified air is available as the oxygen D to be supplied to the generator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater containing a polymer flocculant containing a polymer electrolyte as a main component, which is generated during wastewater treatment or sludge treatment.

Conventionally, suspended solids contained in wastewater such as sewage are concentrated by gravity concentration or pressure flotation concentration, and then an organic polymer flocculant is added to cause flocculation and dehydration treatment. The organic polymer flocculant has the effect of flocculating suspended matter and facilitating dehydration, but is usually added in an excessive amount because the purpose is to further promote flocculation. As a result, excess organic polymer flocculant is discharged into the water that is separated by dehydration.

Since organic polymer flocculants inherently have high viscosity, wastewater containing organic polymer flocculants foams, significantly impairing the aesthetic appearance of the surroundings of treatment equipment. In addition, organic polymer flocculants whose main components are polymer electrolytes are also toxic to fish and shellfish, so if wastewater containing organic polymer flocculants is returned to biological treatment equipment using activated sludge, activated sludge This has an adverse effect on swelling, etc. Furthermore, chemically synthesized organic polymers are toxic to living organisms, so if they are released in large quantities into water bodies such as rivers, they cause secondary pollution such as death of fish and shellfish and impaired growth of plants. '↑-In 2013, cationic polymer flocculants used to treat sewage sludge, etc. adhered to the gills of fish, impairing their biological functions and causing death. The purpose is to render harmless wastewater that contains an excess of organic polymer flocculants, the main component of which is

The key point of the invention is to bring waste water into contact with ozone, and the oxidizing power of ozone causes the polymer flocculant in the waste water to lose its charge and lose its viscosity.

An embodiment of this defense is shown in FIG. The wastewater A containing an organic polymer flocculant is led to the pH adjustment tank 7, and a mineral acid such as sulfuric acid is added thereto to make the wastewater A1 acidic with a pH of 7 or less.
The water is introduced into an aeration tank 1 equipped with an air conditioner and retained therein while being aerated for a certain period of time. When the ozone E is retained, it is distributed to the oxygen supply device 2 and the oxygen generator 3, and the ozone E is released from the diffuser 5 by the blower 4 and comes into contact with the waste water A1.

After residence for a certain period of time, it is discharged as treated water C. Aeration tank 1) Cedar gas B is decomposed by waste gas treatment device B and released into the atmosphere. As the oxygen supplied to the ozone generator 6, pure oxygen or dehumidified air can be used.

The volume of the aeration tank 1 is determined based on factors such as the amount of drainage and the contact efficiency with the ozone E, but a contact time of less than 10 minutes between the caveon E and the wastewater A is sufficient.

Ozone is a gas with strong oxidizing power and can be easily produced using an ozone generator.Ozone is also used for bleaching conventional industrial raw materials and deodorizing sewage treatment equipment.

It is widely used as advanced treatment for COD reduction, decolorization, sterilization, deodorization, etc.

In contrast to the oxidation mechanism of organic matter by ozone, since the oxygen atom at the center of ozone is relatively electron-deficient, it reacts with organic matter having multiple bonds, decomposing it or causing a change in form, resulting in decolorization, Deodorizing.

Effects such as sterilization can be obtained.

On the other hand, anionic or cationic polymer flocculants have a large number of electrolytic groups, and when dissolved in water, they dissociate into polymer ions and low molecular ions (counter ions). Dissociated polymer ions produce high viscosity, and when added to a liquid containing suspended particles such as sludge, it neutralizes the charge held by the suspended particles and creates a coagulation effect by creating bridges between particles. It is.

Table 1 shows the results of ozone treatment of the polymer flocculant.

Table 1 shows the case where the daughterness of the organic polymer flocculant was set to 0.25wt and the treatment was carried out for 5 minutes, and the ozone concentration was 2%wt.
% binding and viscosity were measured using a rotational viscometer.

According to Table 1, after 5 minutes of ozone aeration, the organic polymer flocculant loses its high viscosity and exhibits a viscosity equivalent to that of water. In addition, the cation group, which is an indicator of the viscosity and physical properties of an organic polymer flocculant, was 4.5 (meq/S') before treatment in the case of Imolok IViP-175I-, but after ozone treatment Later on, it drops to 0.4 (meq/f) and loses its activity significantly.(Analysis of cation retention shows that
By colloid titration method using potassium bombinyl sulfate. ) Table 1 Table 2 Table 2 also shows the results of ozone treatment of the dewatered filtrate, which was discharged from the dewatering machine when treating the sewage sludge. The solid content in sewage sludge is 3w
t%, the addition rate of polymer flocculant is o, + to the sludge solid content.
The measured value was obtained when the ozone concentration was 3 wt%, the ozone treatment time was 5 minutes, and the ozone concentration was 2 wt%. According to the results shown in Table 2, the viscosity of the filtrate decreases to the same level as water as a result of aeration of ozone for about 5 minutes, dehydration, and contact with the liquid. It's only one force that can't be generated.

As mentioned above, when ozone is supplied and brought into contact with the organic polymer flocculant aqueous solution itself, the viscosity decreases, and the viscosity of the dehydrated filtrate containing the organic polymer flocculant also decreases. The following effects were obtained when

Because the toxicity of wastewater disappears and the viscosity becomes equal to that of water,
No matter where in the wastewater treatment process it is discharged, it no longer causes a deterioration in the treatment quality, and even when discharged into a river, there is no foaming, which improves the appearance of the watershed.1. was prevented. Furthermore, since the water is non-toxic, there is no risk of death of fish or shellfish or growth problems of plants.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing one embodiment of the present invention. 1:M air tank, 3=Niodine greige machine-5=Diffuse closed)
Mouth/b/i-

Claims (1)

[Claims] In a method for treating wastewater containing an organic polymer flocculant,
Add mineral acid to the wastewater to lower the pH to 7 or lower, and reduce the ozone concentration to 1.
A method for treating wastewater, characterized by having gas-liquid contact with the wastewater at a ratio of ~5 wt% for 10 minutes or less.