JP3178975B2 - Water treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment method including an ozone treatment step for purifying water to be treated by oxidative decomposition of ozone, and a coagulation treatment step performed at any time prior to the ozone treatment step.

[0002]

2. Description of the Related Art Ozone treatment is an effective water treatment method for reducing COD and chromaticity in water to be treated. For example,
Activated sludge treated water obtained by treating human waste or leachate leachate with activated sludge contains a high concentration of biodegradable organic matter at a high concentration, and this biodegradable organic matter causes COD and coloring. Therefore, by treating the activated sludge treated water with ozone, the biodegradable organic matter is partially decomposed to improve its biodegradability, and the ozone oxidized water is treated biologically to improve the biodegradability. The improved organic substances are almost completely decomposed into inorganic substances.

[0003] However, if the treatment is carried out by using only ozone, the treatment performance becomes poor.
Since there is a limit in power and processing time, _Two O_Two , Ultrasonic, U
V and catalysts are used together to promote the ozone reaction.
This is a conventional technique.

[0004]

However, in the above-mentioned conventional ozone reaction accelerating method, when H ₂ O ₂ or ultrasonic waves are used together, there is a problem that there is no effect depending on the nature of the water to be treated.

[0005] When UV is used in combination, there is a problem that the lamp life is short, scales adhere to the lamp surface, the UV light intensity is reduced, and the power consumption is large.

When a catalyst is used in combination, the efficiency of accelerating the ozone reaction is lower than that of the UV method, and the cost is relatively high. The present invention has been made to solve the above problems, and has as its object to promote the ozone reaction economically and effectively.

[0007]

In order to solve the above-mentioned problems, a water treatment method of the present invention comprises an ozone treatment step of purifying water to be treated by an oxidative decomposition action of ozone, and an ozone treatment step prior to the ozone treatment step. In the water treatment method including the coagulation treatment step performed at the time point, the coagulation treatment is performed by adding a coagulant containing manganese, and the water to be treated in which manganese ions remain is introduced into the ozone reaction tank, and in the presence of manganese ions. The ozone treatment is performed.

Further, the water treatment method of the present invention comprises an ozone treatment step of purifying the water to be treated by oxidative decomposition of ozone, and a coagulation treatment step performed at any time prior to the ozone treatment step. , A manganese compound is added together with a coagulant to perform coagulation treatment, and water to be treated in which manganese ions remain is introduced into an ozone reaction tank, and ozone treatment is performed in the presence of manganese ions.

Further, the water treatment method of the present invention is such that ozone oxidized water containing manganese dioxide generated by ozone treatment is introduced into a biological filter, and manganese dioxide is captured and removed by a carrier filled in the biological filter. It was made.

[0010]

A coagulant such as polyiron contains a large amount of manganese (II) as an impurity (in the case of polyiron, 6 g per liter of a stock solution). Manganese ions (hereinafter referred to as Mn ²⁺ ) remain in the water to be treated. When such water to be treated is introduced into an ozone reaction tank and treated with ozone, M
The n ²⁺ is oxidized by ozone to generate MnO ₂ particles, and the Mn ²⁺ or MnO ₂ particles serve as a catalyst to promote the ozone reaction, and the MnO ₂ particles adsorb organic substances. As a result, the oxidative decomposition of organic substances is efficiently performed, and COD is effectively reduced.

Further, a manganese compound is added together with a coagulant.
In addition, Mn is positively ²⁺To exist
As a result, the water to be treated
MnO by reason_Two Particles are formed and Mn²⁺Or MnO_Two 
Particles play the role of catalyst and promote ozone reaction
MnO_Two The particles adsorb organic matter.

Further, since the manganese dioxide MnO ₂ generated by the ozone treatment is captured by the carrier filled in the biological filter, the manganese is prevented from flowing out of the system.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a flow of a water treatment method according to one embodiment of the present invention. In FIG. 1, 1 is raw water which is an organic wastewater such as human waste and leachate leachate, 2 is a residue removal device such as a centrifuge or a dehydrator, 3 is a biological treatment tank comprising an anaerobic tank and an aerobic tank, Reference numeral 4 denotes an ozone reactor, and reference numeral 5 denotes a biological filter bed composed of an aerobic filter bed and an anaerobic filter bed.

The raw water 1 is introduced into the slag removing device 2 to remove suspended matters, and a coagulant C, which is polyiron, is added to the effluent 6 flowing out of the slag removing device 2. Aggregate phosphorus and the like.

The effluent 6 containing aggregates is introduced into the biological treatment tank 3 and mixed with the activated sludge in the tank 3 to biologically decompose biodegradable organic substances and nitrogen contained in the effluent 6. The wastewater is removed and the treated biological water 7 is sent to the ozone reaction tank 4, and the aggregates contained in the effluent water 6 and drawn in are extracted together with the excess sludge.

Then, in the ozone reaction tank 4, the biologically treated water 7 flowing from the biologically treated tank 3 is subjected to ozone treatment, and the organic matter contained in the biologically treated water 7 is oxidatively decomposed to thereby remove the organic matter with improved biodegradability. Use nitrate nitrogen. At this time, the coagulant C added to the outflow water 6 remains in the inflowing biological treatment water 7, and Mn ²⁺ contained as an impurity in the coagulant C is present. When ozone treatment is performed in the presence of such Mn ²⁺ , Mn ²⁺ is oxidized and MnO
_Two particles are formed, and the Mn ²⁺ or MnO ₂ particles act as a catalyst to promote ozonolysis of certain organics. In addition, MnO ₂ particles adsorb organic substances. As a result, oxidative decomposition and removal of organic substances are efficiently performed, and COD
Is effectively reduced.

The ozone-treated water 8 thus treated with ozone is introduced into the biological filter bed 5, and the microorganisms carried on the filter bed 5 allow the organic substances contained in the ozone-treated water 8 with improved biodegradability to be removed. Nitrate nitrogen is biologically decomposed and removed.
At this time, MnO contained in the ozonized water 8 and flowed in
_{Since the two} particles are captured by the carrier filled in the filter bed 5, the treated water 9 containing no MnO ₂ particles flows out of the biological filter bed 5, and the MnO ₂ particles and the organic substances adsorbed on the MnO ₂ particles Is prevented from flowing out of the system. The MnO ₂ particles captured by the carrier are discharged from the filter bed 5 during the carrier washing.

In this manner, COD can be effectively reduced by effectively utilizing Mn ²⁺ contained as an impurity in the coagulant C and adsorbed on MnO ₂ particles and MnO ₂ particles generated by ozone oxidation. Organic matter can be captured by the biological filter 5 disposed downstream of the ozone reactor 4 and prevented from flowing out of the system.

Depending on the properties of the raw water 1, a coagulant C may be added to the raw water 1 to coagulate phosphorus and the like in the raw water 1 and then guided to the residue removing device 2.
The presence of n ²⁺ can promote ozonolysis.

When a manganese-free flocculant such as PAC is used, a manganese compound may be added together with the flocculant C, or the manganese compound may be added at any point before the ozone treatment to form an ozone reaction tank. M in 4
n ²⁺ can be present. Examples of the manganese compound include MnCl ₂ , MnSO ₄ , and Mn (NO ₃ ) ₂ .
What dissolves easily in water to produce Mn ²⁺ may be used.

As a specific example, an aggregating agent is added to biologically treated water obtained by biologically treating human waste to carry out an aggregating treatment, and the agglomerated water is subjected to a membrane separation treatment to obtain a membrane permeate (COD value of about 100).
mg / l), the effective utilization of ozone (reduced COD / O) was 0.2 in the absence of Mn ^2+.
₃ injection rate) was improved to 0.35 in the presence of Mn ²⁺ .

[0022]

As described above, according to the present invention, the water to be treated is subjected to coagulation treatment with a coagulant containing manganese, and the water to be treated is subjected to ozone treatment in the presence of Mn ^2+. Mn ²⁺ or M generated by ozone oxidation
The ozone reaction can be promoted using the nO ₂ particles as a catalyst, and organic substances can be adsorbed by the MnO ₂ particles. As a result, oxidative decomposition of organic substances can be performed efficiently, and CO
D can be effectively reduced. At this time, a coagulant such as polyiron containing manganese as an impurity may be used as the coagulant containing manganese.
Can be reduced.

Further, since such adding a manganese compound together with a flocculant, can also be present Mn ²⁺ in the water to be treated when using the manganese-free coagulant such as PAC, Mn ²⁺ or ozone M generated by oxidation
The ozone reaction can be promoted using the nO ₂ particles as a catalyst, and organic substances can be adsorbed and removed by the MnO ₂ particles.

Further, MnO ₂ generated by the ozone treatment
Since the particles are trapped by the carrier filled in the biological filter bed, it is possible to prevent the MnO ₂ particles and the organic substances adsorbed on the MnO ₂ particles from flowing out of the system.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a flow of a water treatment method according to one embodiment of the present invention.

[Explanation of symbols]

 C flocculant 4 ozone reactor 5 biological filter bed

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C02F 9/00 502 C02F 9/00 502P 502R 504 504A (56) References JP-A-6-154791 (JP, A) JP-A-3-249990 (JP, A) JP-A-3-135418 (JP, A) JP-A-61-245889 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/52-1 / 56 C02F 1/78

Claims (3)

(57) [Claims] 1. A water treatment method comprising: an ozone treatment step of purifying water to be treated by oxidative decomposition of ozone; and a coagulation treatment step performed at any time prior to the ozone treatment step. A water treatment method comprising adding and subjecting coagulation treatment, introducing treated water in which manganese ions remain into an ozone reaction tank, and performing ozone treatment in the presence of manganese ions. 2. A water treatment method comprising: an ozone treatment step of purifying water to be treated by oxidative decomposition of ozone; and a coagulation treatment step performed at any time prior to the ozone treatment step, wherein a manganese compound is added together with a coagulant. A water treatment method comprising adding and subjecting coagulation treatment, introducing treated water in which manganese ions remain into an ozone reaction tank, and performing ozone treatment in the presence of manganese ions. 3. The method according to claim 1, wherein ozonated water containing manganese dioxide generated by the ozone treatment is introduced into a biological filter, and manganese dioxide is captured and removed by a carrier filled in the biological filter. The water treatment method according to claim 2.