JPS58150414A - Removal of malodor - Google Patents

Abstract

PURPOSE:To prevent the lowering of catalytic activity due to the accumulation of a gas phase reaction product, in an ozone catalytic deodorizing method, by providing an activated carbon filter layer in front of a catalytic reactor to collect the gas phase reaction product of a malodorous gas and ozone by said filter layer. CONSTITUTION:A stock gas G containing malodorous components is introduced into either one of activated carbon layers 2 while ozonated air from an ozone generator 3 is mixed therein. Two activated carbon layers 2 are alternately used and, when regeneration is carried out, the passage of the stock gas is blocked by valve manipulation and a gas phase reaction product such as a sulfur compound adhered to the surface of the filter layer 2 is desorbed by the washing effect of water from a washing water tank 3 and a sprayer 4 to reuse said filter layer 2. Ozone from an ozone generator 1 is again mixed in the stock gas passed through the filter layer 2 and, after said stock gas is sufficiently mixed with ozone in a gas mixing tank 7, the mixed gas is discharged to the atmosphere by an exhaust fan 9 while sent to a catalytic reactor 8 to be deodorized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for removing malodor using ozone.

One of the methods for removing bad odors is the ozone catalytic deodorization method (since 1972).
119571)).

This method utilizes the strong oxidizing effect of ozone.
It oxidizes malodorous gas components to odorless components. The feature of the above method is that a catalytic reactor is provided at the ninth stage to promote the oxidation reaction between ozone and malodorous gas components.

As described in the above-mentioned publication, the catalytic reactor is filled with a catalyst in which active metals (eg, oxides of manganese, cobalt, etc.) are supported on the surface using, for example, activated carbon as a carrier.

The main conditions that a catalyst must meet are: (1) high catalytic action, and (2) long catalyst life. especially,
The factors that control the catalyst life are: ■ Mist and dust contained in the gas to be treated (e.g. 'p1), Z
n, Sjn,, As, Na, K,
(2) accumulation of reaction products, thermal changes due to θ overripening, etc.

To explain specifically regarding (b) above, the ozone catalyst deodorization method is mainly aimed at treating malodorous gases generated from sewage treatment facilities, human waste treatment facilities, and similar facilities, so it is targeted. The malodorous gas component is hydrogen sulfide (H2
Sulfur-based compounds such as S ) and methyl mercaptan (0H38H) are the main ones.

For example, the reaction between ozone and hydrogen sulfide proceeds as shown in the equation below, and the final products are sulfur (8) and bad sulfuric acid gas (
SOs) - becomes sulfuric acid (H2BO3).

H2S + 03 -> H2O 8
+ O, (Has + 03 -
*H2O+ 802
(2) 2S + 03 → 280
1 + 'O(3)Bog + 03
-+ 803 + 02
(4) 803 + H2O−+
H2SO4 (6) This final product has the disadvantage that it accumulates on the catalyst surface, impairing the catalyst function and shortening the catalyst life. On the other hand, ozone and malodorous gases react in the gas phase. It was found that the amount was about 50 times the total amount, and the rest reacted on the catalyst.

The inventors believe that if the products reacted in the gas phase can be removed before entering the catalytic reactor, the amount of these products accumulated on the catalyst surface will be reduced and the life of the catalyst will be extended. Thinking friend.

That is, in the ozone catalytic deodorizing method of the present invention, in order to remove gas components generated in the gas phase reaction, a removal filter is provided in front of the catalytic reactor and the gas is guided to the medium reactor.
Before entering the catalytic reactor, ozone is injected again to remove malodorous components in the catalytic reactor.

FIG. 1 shows a systematic diagram of the malodor removal method of the present invention.

This configuration mainly consists of the following elements.

(A) Part of the pre-treatment filter equipped with a water washing regenerator (B)
) Ozone catalyst deodorizing device section Raw gas containing malodorous components enters the deodorizing device from the G line. First, the raw gas enters the activated carbon filter layer 2 while being mixed with ozonized air containing ozone generated from the ozone generator 1 . There are two activated carbon filter layers 2 and they are used alternately. Each activated carbon filter layer 2 is equipped with a water washing regeneration device. That is, the activated carbon filter layer that needs to be regenerated is blocked from flowing raw gas by the pulping operation. Next, due to the cleaning effect of the water sent from the water cleaning tank 3 through the sprayer 4, the sulfur compounds and the like attached to the surface of the filter layer are dissolved and removed by the cleaning water, and the activated carbon filter layer is regenerated and ready for use again. Revive. This cleaning can be performed automatically with a timer. The waste water after washing becomes an acidic liquid with a pH of 1 to 2, containing sulfur compounds such as H and 804, so it is sent to the neutralization tank 5 and then reduced to pH by an alkaline neutralizer 6.
adjusted and released.

The raw gas that has passed through a 2'-ft activated carbon filter is mixed again with ozone sent from the ozone generator 1, sufficiently mixed in the gas mixing tank 7, and then sent to the catalytic reactor 8. The odorless f''1.7'c gas in the catalytic reactor passes through the exhaust fan 9 and is discharged to the atmosphere.

The functions of each device of the present invention are as follows. Odor components and ozone react in the gas phase.

(2) In the activated carbon filter layer 2, reaction products of malodorous components and ozone are collected, and at the same time, dust removal is performed. Hydrocarbons (0, to C7 or higher) in the raw gas are also adsorbed and removed.

(3) The activated carbon filter can be regenerated and used by appropriately desorbing the reaction products (mainly sulfur compounds) collected in the activated carbon filter layer 2 using the water washing regeneration device 3.4.

(4) If two single-layer activated carbon filters are installed in parallel, they can be regenerated even when the equipment is in operation.

(5) Since the pH of the wastewater generated during regeneration is as low as 1 to 2, the pH is adjusted and discharged.

(6) The catalytic reactor 8 is made of, for example, a carbonaceous material (e.g.
Granular, crushed or powdered activated carbon, graphite,
One or more metal oxides such as vanadium, chromium, manganese, iron, cobalt, nickel, steel, silver, zinc, etc. are supported on a catalyst carrier made of carbon fiber, etc.
If necessary, platinum, palladium, rhodium, ruthenium An supported as a co-catalyst together with these metal oxides are filled as a catalyst.
Publication No. 71) 0 When the gas that has passed through the gas mixing tank 7 passes through the catalytic reactor, the reaction between the unreacted malodorous gas and ozone is completed, and at the same time, the self-decomposition of excess ozone is completed.

This method produces the following effects.

(1) The product of the gas phase reaction between the malodorous components in the raw gas and ozone is collected in a single layer of the activated carbon filter, which prevents accumulation in the rear catalyst layer and prevents a decrease in catalyst activity due to accumulation. .

(2) The single-layer activated carbon filter is equipped with a water washing and regenerating device, so it can be regenerated and reused as needed. (3) The pH of the waste water generated during regeneration is adjusted, so it can be discharged.

(4) In the catalytic reactor, on the surface of the packed catalyst,
Since the reaction between the malodorous components and ozone is completed, the raw gas becomes odorless.

(5) Excess waste ozone is simultaneously self-decomposed and treated.

Example 1 Figure 2 shows an example of the reaction between ozone and malodorous components in the gas phase. The reaction rate between ozone and malodorous components is approximately 50 to 6 when ozone/malodorous components (molar ratio) = 3 and reaction time = 5 seconds or more.
It was 0chi. In the figure, O is hydrogen sulfide 17 ppm, △ is methyl mercaptan 20 ppm, and Mu is ammonia 21 ppm.
m, methyl sulfide 7 ppm, ■ trimethylamine 6
The case of 7 ppm is shown.

The following components of the reaction product were confirmed by gas chromatography.

Table 1: Reaction products of ozone and malodorous components When granular activated carbon (charcoal from coconut) collected from the first layer of a used activated carbon filter was analyzed, it was found that sulfur compounds had accumulated by more than 1 weight on an S (sulfur) basis. . A water washing test was conducted using this used activated carbon as a sample. Used activated carbon 1
00- was added with 50 ffid'vf of water, stirred, allowed to stand, then decanted, and 500- of water was added again to continue washing, and the number of water washes and the effect of removing sulfur compounds were investigated. The results are shown in FIG.

From this, it has been found that if the used activated carbon is washed with water at least five times, 80 to 90% or more of the sulfur compounds accumulated in the used activated carbon are removed, and the function of the activated carbon is improved.

Example 2 In a sewage treatment facility, bad odors generated from the settling basin, primary settling basin, aeration tank, and sludge treatment room are sucked out using an exhaust fan, and
Deodorization was performed according to the system diagram shown in the figure. The activated carbon filter for removing gas phase reaction products uses granular coconut shell activated carbon (4 to 6
[Mesh] 1150w+i was filled, and gas was flowed at a flow rate of 0.5m/8eC. The activated carbon filter was washed with water and regenerated repeatedly every 3000 hours after the start of operation.

Activated carbon supporting manganese oxide was used as a catalyst. Ozone was injected at 1.5 ppm in front of the activated carbon filter and 1.5 ppm in the front of the gas mixing tank.

For example, the effect of removing malodorous components for hydrogen sulfide after 500 hours after the start of operation was as follows, and the effect of the filter was recognized.

For example, the effect of removing odor components for hydrogen sulfide after 12,000 hours after the start of operation (the activated carbon filter is regenerated once each time) is 0, which indicates that the filter was washed with water.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the method of the present invention,
Figure 2 is a graph showing the reactivity of ozone and odor components in the gas phase in the present invention, and Figure 6 is a graph showing the cleaning effect of spent activated carbon in the present invention. Sub-agent Ryo Hagiwara −

Claims (1)

[Claims] In the odor removal method using ozone, ozone is injected into the malodorous gas, and a single layer of activated carbon filter is installed in the downstream part of the gas to adsorb the gas phase reaction product of the malodorous gas and ozone.After that, ozone is injected again to catalyze the reaction. A method for removing bad odors characterized by carrying out a gas phase reaction in a reactor.