JPH0929264A - Method for removing cod in drainage water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and inexpensively remove hardly decomposable COD in drainage by a method wherein, after phenols are oxidized by passing them through an enzyme-immobilized column, they are incorporated into drainage to precipate the COD in the drainage. SOLUTION: When COD in drainage is removed in a waste water treatment plant, phenols oxidized by passing them through an enzyme-immobilized column are incorporated into the waste water. In this case, when phenol is passed through e.g. tyrosinase-immobilized column, ortho-quinone prepd. by oxidizing phenol is generated. When this quinone is incorporated into the waste water, a polymer is formed from the oxidized ortho-quinone, and phenols and COD are involved into the polymer to produce precipitate and COD is removed. In addition, if necessary, when a flocculating agent is incorporated, flocculation and precipitation reaction is accelerated and COD and other toxic components can be eliminated more effectively but, when using high-molecular phenols, formation of the polymer can be rapidly performed to make the flocculating agent unnecessary.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for removing COD in wastewater.

[0002]

2. Description of the Related Art Wastewater treatment at present sewage treatment plants is
Although mainly used for biological treatment such as activated sludge method, chemical factory effluent may contain COD such as persistent phenol which cannot be removed by biological treatment. May be discharged into the environment as it is. Therefore, attempts have been made to remove COD that is difficult to decompose by advanced treatments such as chemical oxidation and adsorption of activated carbon, but there is a problem in terms of cost.

Therefore, as a method of removing COD that is difficult to decompose at low cost, utilization of the oxidative action of an enzyme has been studied. One of the typical methods is to add phenol oxidase into the waste water together with a flocculant. According to this method, the phenol component in the waste water is oxidized and polymerized / polymerized by the enzyme, and by adding the coagulant, it is precipitated together with other substances and removed.
However, this method has a problem that the phenol oxidase must be removed from the treated water together with the precipitate.

In order to solve such a problem, a phenol oxidase is immobilized on a column, waste water containing a phenol component is passed through the immobilized column to be oxidized, and then a coagulant is added. The method of doing is also proposed. However, this method has a problem in terms of stability of the immobilized enzyme because the immobilized enzyme directly contacts the wastewater containing impurities. Further, in this method, the reaction proceeds in the column to form flocs, which may cause clogging.
Regarding these conventional technologies, refer to “Industrial Water”, No. 420.
No., September 1993, pages 24-36.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and easily and inexpensively removes persistent COD such as phenol contained in wastewater from chemical plants. It was made in order to provide a method for removing COD in wastewater that can be obtained.

[0006]

The present invention, which has been made to solve the above-mentioned problems, provides a method in which phenols are passed through an enzyme-immobilized column to be oxidized and then added to the waste water, and C in the waste water is added.
It is characterized by precipitating OD. In addition,
A flocculant may be added together with the oxidized phenol, or high molecular weight phenols may be used.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the enzyme-immobilized column used in the present invention, enzymes such as tyrosinase, peroxidase, and laccase, which are enzymes capable of oxidizing phenols, are immobilized. The phenols referred to in the present specification mean not only phenol, which is a phenol in a narrow sense, but also various aromatic hydroxy compounds such as catechin, pyrogallol, and cresol. As the carrier packed in the column, for example, porous ceramics can be used. Entrapment fixation by gel or semipermeable membrane is not preferable because the enzyme is easily released.

For example, when phenol is passed through a column on which tyrosinase is immobilized, the reaction as shown in FIG. 1 proceeds to produce orthoquinone in which phenol is oxidized. When this is added to the wastewater as shown in FIG. 2, when the oxidized orthoquinones form a polymer, not only phenols in the wastewater but also other COD components are involved to form a precipitate, and COD is removed. At this time,
When a coagulant is also added as shown in FIG. 3, the coagulation-precipitation reaction is promoted, and COD and other harmful components are more effectively removed.

Further, as shown in FIG. 4, when a high molecular weight phenol is used, a polymer is rapidly formed in the waste water, so that no coagulant may be added.

In any case, according to the present invention, since the enzyme is immobilized and used, the enzyme does not flow out into the waste water, and it is not necessary to remove the enzyme in the subsequent step. Further, according to the present invention, since the waste water is not brought into direct contact with the enzyme-immobilized column, clogging does not occur unlike the conventional case. Moreover, persistent C that could not be removed by biological treatment
OD can be removed easily and at low cost.

[0011]

Examples of the present invention will be described below. Porous ceramic carrier manufactured by Nippon Insulators Co., Ltd. (trade name: SM-10)
To 1 g, 3 mL of a 10 mg / mL tyrosinase solution was added and shaken at room temperature for 24 hours to immobilize the enzyme. The tyrosinase used was manufactured by Wako Pure Chemical Industries, Ltd. The ceramic carrier was thoroughly washed and packed in a column. Next, 90 mL of a phenol solution with a concentration of 50 mg / L and COD _Mn : 106 mg / L
Was passed through the column at a flow rate of 1 mL / min for 2 hours, and phenol was oxidized with tyrosinase to obtain a phenol oxide solution.

This phenol oxide solution was added to COD _Cr :
96.8mg / L, COD _Mn : 65.1mg / L, BOD: 90.7mg / L, T
OC: 82.2 mg / L of garbage was added to the leachate at a rate of 30% V / V, and after shaking at room temperature for 18.5 hours, a sulfuric acid band was added as a coagulant so that the final concentration of Al was 51 mg / L. did. Then, the produced aggregated precipitate was separated by a centrifuge, and the COD of the supernatant water was measured. Table 1 shows the results. In addition,
As a result of evaluating the stability of the immobilized enzyme by repeating the same experiment, it was confirmed that almost the same COD removal rate was obtained in the 10th test.

[0013]

[Table 1]

[0014]

As described above, according to the present invention, it is possible to easily and inexpensively remove the hardly decomposable COD in the waste water, which cannot be removed by the conventional biological treatment. Moreover, according to the present invention, since the wastewater is not directly contacted with the enzyme-immobilized column, there is an advantage that clogging does not occur unlike the conventional case.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the oxidation reaction of phenol by tyrosinase.

FIG. 2 is a process explanatory diagram of the invention of claim 1;

FIG. 3 is a process explanatory diagram of the invention of claim 2;

FIG. 4 is a process explanatory view of the invention of claim 3;

Front page continued (72) Inventor Kenji Tatsumi 304, 5-518 Matsushiro, Tsukuba, Ibaraki

Claims (3)

[Claims] 1. A method for removing COD from wastewater, which comprises passing a phenol through an enzyme-immobilized column to oxidize it and then adding it to the wastewater to precipitate COD in the wastewater. 2. CO in wastewater, characterized in that phenols are passed through an enzyme-immobilized column to be oxidized and added to the wastewater together with a coagulant to precipitate COD in the wastewater.
D removal method. 3. High molecular weight phenols are passed through an enzyme-immobilized column to be oxidized and then added to the wastewater, and C in the wastewater is added.
A method for removing COD in wastewater, which comprises precipitating OD.