JPS6048189A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To save the amt. of powdered activated carbon to be added by adding powdered activated carbon and an inorganic flocculant to the waste water after the first-stage flocculating treatment, separating solid from liquid, and returning the generated sludge contg. activated carbon to the first-stage flocculating treatment. CONSTITUTION:An inorganic flocculant is added into the No. 1 reaction vessel 4, and the pH is controlled by a pH regulating agent to form flocs. The sludge contg. powdered activated carbon returned from the second stage 2 through the third stage 3 is added. The diameter of the floc in the waste water is enlarged by further adding high molecular flocculant, and the solid deposit separated from the liquid in the No. 1 settling vessel 6 is discharged as sludge. The supernatant water is introduced into the second stage 2, and powdered activated carbon, an inorganic flocculant, and the pH regulating agent are added into the No. 3 reaction vessel 7 wherein the remaining pollutional material such as COD is flocculated and adsorbed by the activated carbon. Then the high molecular flocculant is added, and the solid is separated from the liquid in the No. 2 settling vessel 8. The deposit is returned to the first stage 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater. More specifically, the present invention relates to (i) a method for treating wastewater using unactivated carbon and an inorganic flocculant.

Conventionally, when treating wastewater using powdered activated carbon, a two-stage coagulation treatment method was used in which unactivated carbon was added to the wastewater in two parts, thereby reducing the amount added. It was

In order to further reduce the amount of powdered activated carbon added, the present inventor conducted various studies and found that in the two-stage flocculation treatment method described in 1. We have discovered that the amount of powdered activated carbon added can be significantly reduced by adding unactivated carbon or powdered activated carbon-containing sludge and reacting after adding f-collecting agent and reacting, and have arrived at the present invention.

That is, the present invention adds sludge containing unactivated carbon to wastewater (after adding a flocculant, it will be returned from the second step described below), and converts the resulting sludge into a solid-liquid fraction! The first step is to add 15) unactivated carbon and an inorganic flocculant to the water treated in the first step, and the second step is to roll the solid-liquid precipitate, which is generated in the second step. The 1st book containing
This is a modification of the wastewater treatment method that consists of the third step of returning the wastewater to the plant.

In general, the flocculent components in wastewater that can be removed with flocculants have relatively convex molecules, and those that can be removed with 71Ii+'l charcoal have lower molecular weights. According to Masaru No. 7, it is possible to remove both high-molecular and low-molecular substances by using a collecting agent. Therefore, in the present invention, an inorganic coagulant 11S agent is added and the inorganic coagulant 11S can be removed in advance by activated carbon. By removing the substances, the amount of unactivated carbon added can be reduced without reducing the amount of unactivated carbon added.Also, by adding an inorganic flocculant, the flocs can be increased, the settling rate or flotation rate can be increased, and the treated water s Water quality such as s'b?4 degrees can be improved.

In addition, since Co11 in wastewater cannot be removed without an inorganic coagulant, the coagulants used in the present invention are limited to unactivated carbon and inorganic coagulants. This is because when an inorganic flocculant that produces .

Hereinafter, the present invention will be specifically described with reference to the drawings.

The drawing shows a processing flowchart of an embodiment of the present invention,
The first step is No. 1 reaction tank, No. 2 reaction tank, No.
The second step consists of a No. 3 reaction tank and a No. 2 precipitation tank. The third and second stages consist of a device for returning sludge, such as a sludge pump (not shown).

In the No. 1 reaction tank, an inorganic flocculant is first added to the wastewater introduced in the first step, and pl+ is adjusted using a ρ11 regulator to form and remove flocs. Next, sludge containing unactivated carbon (which was returned from the 2nd stage to the 3rd stage) is added and reacted in the No. 2 reaction tank, and COD in the wastewater is adsorbed and removed by powdered activated carbon. .

Furthermore, it is preferable to add a polymer flocculant at this time because it can increase the diameter of flocs in the wastewater and improve the sedimentation rate. As such a polymer flocculant, for example, a partial hydrolyzate of polyacrylamide is added at a rate of several inches/1. Then No, 1 sink? Solid-liquid separation is carried out in 941'l, the sediment is discharged as sludge, and clear water is sent to the second process.

Powdered activated carbon, an inorganic flocculant, and a PL+ regulator are added to the wastewater introduced into the second step in an N, O, 3 reaction tank to remove residual COD and other pollutants that were not removed in the first step. Adsorbed by floc formation or activated carbon.

Add a preferably polymeric agent 11≦ to No. 2.
Separate solid and liquid in a reaction tank. The precipitate is 15) returned to the first step as sludge containing unactivated carbon by a device (not shown) in the third step, and the clear water is collected as treated water.

The above F■ (as a coagulant, aluminum salt, iron salt,
Magnesium salts or calcium salts are used,
Examples include aluminum sulfate (aluminum), ferrous chloride, ferrous chloride, ferrous sulfate, ferric sulfate, aluminum chloride, polyaluminum chloride, mag 7 sulfate, soum, magnesium chloride, etc. Depending on the water quality, properties, etc. of the wastewater, it can be selected as desired.

The addition of the inorganic flocculant in the first step is the
In order to remove OO, t5) must be done before the addition of unactivated carbon. This is because the best results can be obtained by stirring for a certain period of time after adding the inorganic flocculant and adding powdered activated carbon when flocs are formed.

In addition, the addition of inorganic flocculant in the first step and the addition of PL + adjuster need to be determined appropriately based on the 4R5ft of GO11, since COO is removed by hydroxide and activated carbon. be. Therefore, in the process n;1,
It is necessary to conduct a simple experiment on the wastewater to be treated and determine the above points.

1st] For the addition of powdered activated carbon in the second step, the entire amount is taken out from the sedimentation tank in the second step and sent back. - You can use the powdered activated carbon contained in the sludge, or you can Additional amounts may be added.

For the solid-liquid separation in the first step and the second step, a well-known type of settling tank can be used.

In addition, the sludge discharged from the settling tank in the first step is
After dehydration, the waste is incinerated or otherwise disposed of.

In the second step, in order to increase the OD removal rate,
The inorganic flocculant is preferably added prior to the addition of unactivated carbon. Also, the addition li1 and ρI after addition
Regarding the I-wing adjustment and the polymer flocculant, it is the same as in the first step.

In the second culm, the amount of unactivated carbon (15) compared to C[]D is overwhelmingly large, so Cu11 that was not removed in the first step can be removed and good treated water (! I
I can do things.

Example A test was conducted on activated sludge treated water of zero-phase softened wastewater containing pl+ 8.0 and C0Dxn 347 ppm according to the treatment flowchart 1 shown in the drawing. No. 1 reaction tank added amount of sulfuric acid band 11000pp, pH 7,
lrA I'l' time 10 minutes, +io, 3 reaction vessels 45) Unactivated carbon (Tararecol IIPK) 310 p
Sulfuric acid hunt 2 (10 ppm, pH 7
, 1 week (12 hours and 30 minutes, CODM++9
．． lppm of treated water was obtained. The stirring time in the No. 2 reaction tank was 30 minutes, the addition of a polymer flocculant (anion) was 12 ppm, and the settling time in the settling tank was 30 minutes.

Comparative Example 1 A test was conducted on the same wastewater as in the example except that sulfuric acid hand was not added in the N091 reaction tank, and the treated water GOIIMn was 56 ppm, and powdered activated carbon was added in large quantities. Even if (200M. l Oppm
The following processing could not be performed.

Comparative Example 2 The same wastewater as in the example was subjected to one-stage treatment up to the No. 1 sedimentation tank (no sludge return, and the No. 2 reaction tank was subjected to powdered activated carbon addition). In order to treat the treated water (q), sulfate band I (l tl Op p m
, W) It was necessary to add 850 ppm of unactivated carbon. In addition, if sulfuric acid hand is not added, 1'5) Even if unactivated carbon is added to a high concentration of F;
This is because it is not possible to process ODMll to 10 ppm or less.

Furthermore, when the order of addition of unactivated carbon was reversed, it was necessary to add 1300 ppm of powdered activated carbon in order to obtain treated water of the same level as in the example.

[Brief explanation of the drawing]

The accompanying drawing is a processing flowchart showing one embodiment of the present invention.

Claims (1)

[Claims] After adding an inorganic flocculant to the wastewater, the sludge containing powdered activated carbon returned from the second step (described later) is added, and the resulting sediment is solid-liquid separated. A second step in which the precipitate produced by adding powdered activated carbon and an inorganic coagulant 41% agent to water is separated into solid and liquid, and a third step in which the IQ mud containing powdered activated carbon generated in the second step is returned to the first upper stage. How to treat wastewater