JPS60209299A - Treatment of waste water coexisting metallic ion and organic material - Google Patents

Abstract

PURPOSE:To make waste water harmless by adding an acid to the waste water wherein metallic ions and organic materials are coexistant, removing the formed precipitate, and electrolyzing at <=3pH. CONSTITUTION:Waste plating water 1 is transported into a treating vessel 2, and the pH is regulated by adding an acid 3. The supernatant water 4 of said waste water is then transported into an electrolytic cell 5. The electrolyte is regulated at <=3.0pH, and electrolyze to deposit copper ions in the waste water. The deposit is removed, and simultaneously the organic materials contained in the waste water 1 are oxidized and decomposed to obtain the material which is easily decomposable with microorganisms and harmless to the microorganisms. Then the treated wate 6 which is electrolyzed in treating vessel 5 is transported into the biological regulating vessel 7, and diluted, at need, with return discharge water 15 to a desired concn. of organic materials to obtain inflowing water 8 to be biologically treated. The inflowing water 8 is transported into a biological treating vessel 9 wherein remaining organic materials are decomposed by microorganisms.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating wastewater in which metal ions and organic substances coexist.

[Prior art and its problems]

Conventionally, methods such as combustion treatment, evaporation concentration treatment, and biological treatment have been used to treat wastewater in which metal ions and organic substances coexist. There are safety issues, and the evaporative concentration process reduces thermal efficiency, generates odors due to thermal decomposition,
a■ to the condensed water.

There is a problem of outflow of COD components, and in any case, there are many drawbacks in terms of economy such as equipment cost and running cost, safety, and efficiency.

From the viewpoint of treatment cost and safety, microbial treatment, such as the activated sludge method, is the most promising method, but if metal ions, organic substances, etc. that inhibit microorganisms are present in the wastewater, Applying microbial treatments is often difficult.

[Purpose of the invention]

The present invention solves the above-mentioned problems and provides a method for treating wastewater containing metal ions and organic substances and rendering it harmless.

[Structure of the invention]

The present invention consists of a first step of adding an acid to wastewater containing metal ions and organic substances and removing the generated precipitate, and a second step of electrolyzing the treated water obtained in the first step. This is a method for treating wastewater in which metal ions and organic substances coexist, including a third step of microbially treating the resulting treated water.

[Detailed explanation of configuration]

The present invention relates to the treatment of plating wastewater containing metal ions, for example, copper plating wastewater containing a large amount of organic substances that have an ultraviolet effect on microorganisms, such as complexing agents, surfactants, brighteners, etc. First, acid is added to the waste water to remove the generated precipitate by, for example, adjusting the pH to 3.0 or less, and then electrolysis is performed after the pH of the removed liquid is brought to 3.0 or less. Metal ion copper is deposited on the cathode and removed, and organic matter is decomposed. Furthermore, the concentration of residual organic matter in the treated water is diluted and adjusted to a desired concentration, and treated with microorganisms.

In addition, the electrolytic treatment is adjusted so that the concentration of copper ions or organic substances remaining in the electrolyzed water is such that it does not inhibit the growth of microorganisms.

In general, the BOD,
OCxQ, /C It is said that biological treatment can be applied to the treated water if electrolysis treatment is performed so that the biodegradation rate is 40- or higher (
Zensuke Inoue: Water and wastewater, 14. N(1,2,lo(1
972)).

The present invention will be described in detail below based on FIG. 1st
1 in the figure is plating wastewater. This plating wastewater 1 is transported to a treatment tank 2, and sulfuric acid 3, for example, is added as an acid to adjust the pH to, for example, 3.0 or less. Next, the supernatant water of the plating wastewater 4
The plating wastewater 1 is transported to an electrolytic tank 5, where the pH of the electrolytic solution is adjusted to 3.0 or lower and subjected to electrolysis treatment.
Copper ions contained in the wastewater are deposited on the cathode and removed from the wastewater. At the same time, organic matter having an ultraviolet effect on microorganisms contained in the plating wastewater 1 is removed by electrolysis treatment.
It is easily decomposed by microorganisms and is oxidized and decomposed into something that has little inhibitory effect on microorganisms.

Next, in the electrolysis treatment tank 5, the electrolyzed treated water 6 is transported to the microbial treatment adjustment tank 7, and diluted and adjusted to a desired organic matter concentration using return discharge water 15 as necessary. Microbial treatment inflow water 8. This microbial-treated inflow water 8 is transported to a microbial treatment tank 9, and residual organic matter is decomposed by microorganisms. There are two main types of wastewater treatment methods using microorganisms: aerobic treatment and anaerobic treatment, but in the present invention, there is a risk of heavy metal ions flowing in, so the method is relatively less affected by heavy metal ions. Aerobic treatment is preferred. Furthermore, it is highly desirable to use a contact aeration method that is less susceptible to fluctuations in inflow water quality. In addition, in the microbial treatment tank 9, acid, alkali, etc.
By adding the H regulator IO, the pH in the tank is adjusted to 6 to 8, which is suitable for the growth of organisms. Further, a nutrient salt 11 containing phosphate, ammonium nitrate, etc. is added as necessary. The decomposed microbially treated inflow water 8 is transported to the sedimentation tank 13 as microbially treated effluent 12 . In the sedimentation tank 13, organisms contained in the microbially treated effluent 12 are precipitated, and they are extracted as surplus sludge 16. Further, the supernatant water is discharged as discharge water 14. In addition, when diluting the electrolyzed water 6 flowing into the microbial treatment adjustment tank 7, a part of the discharge water 14 is transported to the microbial treatment adjustment tank 7 as return discharge water 15, and used as dilution water. It is also possible to use

Examples of the present invention are shown below.

(Example) Sulfuric acid was added to the copper plating wastewater shown in Table 1 to adjust the pH to 3.
0 or less, and the generated precipitate was removed. Next, the treated water was electrolytically treated under the electrolytic conditions shown in Table 2.

[Table 1] Water quality of wastewater [Table 2] Electrolysis conditions Residual copper ion concentration in treated water after electrolysis treatment is lppm
Hereinafter, the COD concentration was below 2,501)p voice.

Next, residual organic matter in the electrolyzed water was treated by a contact aeration method. The conditions of the contact aeration method are shown in [Table 3], and the biodegradation rate of electrolyzed water and the results of microbial treatment are shown in [Table 4].
Table]. The microorganisms used in this example were acclimatized using activated sludge treated with domestic wastewater as seed sludge.

[Table 3] Contact aeration conditions [Table 4] Biodegradation rate and biological treatment results In order to clarify the effects of the present invention, the biodegradation rate and biological treatment when electrolytically treated without using the present invention were The results of the treatment are also shown in [Table 4].

As is clear from Table 4, according to the present invention, wastewater containing metal ions and organic substances can be efficiently treated.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to recover metals, which are valuable substances, from plating wastewater in which metal ions and organic substances coexist, and finally, it has the effect of realizing detoxification treatment by microbial treatment. It is.

[Brief explanation of the drawing]

FIG. 1 is a processing flow diagram according to the present invention. In the figure, 1 is plating wastewater, 2 is a treatment tank, 3 is sulfuric acid, 4 is supernatant water, 5 is an electrolysis tank, 6 is electrolyzed water, 7 is a microbial treatment adjustment tank, 8 is microbial treatment inflow water, and 9 is biological treatment tank,
10 is a pH adjuster, 11 is a nutrient salt, 12 is a microbial treatment effluent, 13 is a settling tank, 14 is effluent, 15 is return effluent, and 16 is excess sludge. Patent applicant: NEC Corporation

Claims (1)

[Claims] (1) A method for treating wastewater in which metal ions and organic substances coexist, which includes a first step of adding an acid to the wastewater and removing the generated precipitate, and a method of treating wastewater in which metal ions and organic substances coexist.
A method for treating wastewater in which metal ions and organic substances coexist, characterized by carrying out a second step of performing electrolysis at ua of 0 or less, and a third step of treating the treated water obtained in the second step with microorganisms.