JP2945402B2 - Sludge deodorant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a deodorant for removing malodors generated from organic sludge such as sewage, human waste treatment plants, and organic industrial wastewater.

[Conventional technology]

Organic sludge generated from sewage, human waste treatment plants, organic industrial wastewater, and the like is treated by adding a polymer flocculant or the like and dehydrating with a screw decanter, a belt press, or the like. The dehydrated cake is disposed of by incineration and landfill. However, when the dissolved oxygen is exhausted, the organic sludge starts to rot and generates sulfide-based malodorous gas such as hydrogen sulfide and methyl mercaptan. In particular, hydrogen sulfide is a serious problem not only because of its odor, but also because of its toxicity to the human body and its corrosion to equipment. The following methods are currently used as a method for deodorizing odorous gas.

(1) Chemical cleaning method using acid, alkali and the like.

(2) Adsorption method using activated carbon and ion exchange resin.

(3) Combustion methods such as direct combustion method and catalytic combustion method.

(4) A chemical addition method using an oxidizing agent or the like.

Of these methods, methods (1) to (3) are suitable for treating high-concentration odors. However, it is necessary to collect the odors by a duct and send them to a processing device, and the area around the dehydrator is open. It is difficult to call it a very efficient method because of its large volume. On the other hand, the chemical addition method only needs to add a chemical to the sludge, and is a method suitable for deodorizing around the dehydrator.

However, the conventional chemical addition method is effective at the moment of addition, but the persistence of the deodorizing effect is poor, and sludge storage tanks, dehydrators,
In each process such as dewatering cake hopper, truck carry-out and landfill, deodorization could not be performed effectively. or,
Due to poor sustainability, the deodorizing effect is uneasy, and the cost is increasing. For this reason, various chemicals and treatment methods have been proposed as deodorizing (deodorizing) agents.
A substance consisting of ascorbic acid and a divalent iron compound (Japanese Patent Publication No. 61
No. 43091) A method using a zinc compound (JP-A-63-2)
05197), a deodorant containing zinc and trivalent iron as main components (JP-A-63-205198), and a compound containing ascorbic acid or erythorbic acid and water-soluble cupric acid (JP-A-63-195198). JP-A-147543) and a compound in which a hypochlorite and a metal compound are impregnated into a granular material (JP-A-63-178846) are known.

[Problems to be solved by the invention]

However, all of the proposed methods are effective immediately after the addition but have insufficient sustainability. Also, JP-A-63-17
Mixing hypochlorite and metal compounds described in No. 8846 as an aqueous solution will cause decomposition of hypochlorite and precipitation of metal hydroxide, so use such a combination as an aqueous solution. Is something that cannot be done.

An object of the present invention is to provide a sludge deodorant which can be easily added to sludge and has excellent durability.

[Means for solving the problem]

The gist of the present invention resides in a sludge deodorant comprising a water-soluble zinc compound, an organic water-soluble rot inhibitor and water.

Sludge to be treated in the present invention is organic sludge generated from biological treatment of high BOD wastewater, and examples thereof include sludge generated from sewage and human waste treatment plants, sludge generated from food industry, chemical industry, and the like. Can be mentioned.

In the present invention, examples of the water-soluble zinc compound, which is a component of the sludge deodorant, include salts such as zinc acetate and chlorides such as zinc chloride.

Examples of the organic water-soluble rust preventive include triazine-based compounds such as 1,3,5-tris (β-oxyethyl) hexahydrotriazine and industrial rust preventives represented by metal salts of organic acids, benzoic acid, and the like. It is used as an antiseptic for foods represented by salicylic acid, dehydroacetic acid, salts of parahydroxybenzoic acid, etc. or as a pharmaceutical antiseptic represented by benzalkonium chloride, benzyl alcohol, etc. Can be mentioned.

Water-soluble zinc compound (A) in the sludge deodorant of the present invention
The composition ratio A / B of the organic rot antioxidant (B) is not particularly limited, but usually may be in the range of about 99/1 to 1/99 (parts by weight), and may be 90/10 to 50/50 ( (Parts by weight) is more preferable.

Further, the composition ratio of the water-soluble zinc compound, the organic anti-rotting agent (hereinafter collectively referred to as “active ingredient”) and water is not particularly limited, but the amount of the active ingredient in the sludge deodorant is about 5 to 60. It is preferable that the amount is about% by weight.

It is not clear why the sludge deodorant of the present invention comprising such a blend is effective for deodorizing sludge, but mainly a water-soluble zinc compound reacts with already generated malodorous components such as hydrogen sulfide to remove this. However, it is considered that the organic putrefaction inhibitor prevents the generation of offensive odor gas.

 Next, a method of using the sludge deodorant will be described.

When the sludge deodorant of the present invention is used, the timing and place for adding the sludge deodorant are not particularly limited. However, in order to enhance the deodorizing effect, the sludge deodorant is preferably at a stage before the decay of the sludge proceeds. Therefore, the sludge is usually added almost simultaneously with the sludge being charged into the sludge storage tank. However, the sludge deodorant may be added alone or may be added in a state of being mixed with the polymer flocculant solution. If the decay is severe, the sludge may be added to a sludge thickening tank provided before the sludge storage tank, if necessary. The reaction time after the addition of the sludge deodorant does not need to be particularly considered.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples. still,
In the examples, the amount of the deodorant added is a weight ratio to the sludge.

Examples 1 to 9, Comparative Examples 1, 2 pH; 5.4, SS; 2.05%, loss on ignition (hereinafter referred to as "VTS"); 67.5%, M-alkalinity; 300 ml was collected in a poly bottle. Then the first
After adding the deodorant of the composition and amount shown in the table and shaking 10 times, measure the concentration of gaseous odor gas with a gas detector tube, and determine the amount of hydrogen sulfide that is the main component of odor below the detection limit. I asked.

Using this amount as the amount of deodorant added, the sludge in the plastic bottle was sealed and stored as it was, and the persistence of the deodorizing effect was measured until 5 days later. In each case, the sustained effect of deodorization on sludge was very good. However, Comparative Examples 1 and 2 required a large amount of hydrogen sulfide to be below the detection limit.

Comparative Example 3 The odor was measured in the same manner as in Example 1 except that no deodorant was added. As a result, hydrogen sulfide,
The amount of methyl mercaptan increased significantly, leading to a very foul odor.

Comparative Examples 4 to 12 As the deodorizing agents, the oxidizing agents or metal salts shown in Table 1 were added, and the odor was measured in the other conditions as in Example 1. As a result, immediately after the addition, hydrogen sulfide and methyl mercaptan were removed and the deodorizing effect was obtained. However, the odorous gas increased remarkably over time, and various odor components were detected as in the case where no chemical was added.

Examples 10 to 18, Comparative Examples 13 and 14 300 ml of the same sludge as in Example 1 was collected in a 500 ml beaker, and each deodorant was added until the amount of hydrogen sulfide became below the detection limit, and mixed for 1 minute with a spatula. did. Next, a polymer flocculant Diafloc KP-201G (manufactured by Diafloc Co., Ltd., dimethylaminomethacrylate quaternary salt homopolymer, molecular weight 3,000,000) was added to sludge at 150 ppm, and the mixture was stirred and mixed with a spatula for 1 minute to remove the floc. It was formed and dehydrated by a belt press type dehydrator.

The obtained cake was sealed and stored in a 250 ml plastic bottle, and the odor gas concentration was measured over time to evaluate the sustained effect of deodorization.

In Comparative Examples 13 and 14, a large amount of hydrogen sulfide was required to be below the detection limit, and the amount of hydrogen sulfide generated in the cake increased over time.

Comparative Example 15 When no other chemical was added and the other conditions were exactly the same as those in Example 10, the odor of the cake was weak immediately after dehydration, but the odorous gas was generated over time and became very odorous.

Comparative Examples 16 to 24 The oxidizing agents or metal salts shown in Table 2 were added as deodorants, and the other conditions were the same as in Example 12. As a result, immediately after the dehydration, the odor of the cake was weak, but the odor gas was generated over time and became very odorous, and the odor was almost the same as in the case where no chemical was added.

Example 19 A test of a deodorant was carried out in a sewage sludge treatment facility as shown in FIG. Sludge properties are SS1.86%, pH5.4, VTS7
It was 2.4%. A predetermined amount of the deodorant was put into the sludge storage tank and mixed with a stirrer for 30 minutes. A belt press type dehydrator manufactured by Tsukishima Kikai Co., Ltd. was used as a dehydrator, and Diafloc KP-201G was used as a polymer flocculant for sludge dehydration.

The results are shown in Table 3, and the deodorized state from the sludge storage tank to the dewatered cake hopper was good. Even if the sludge remaining in the sludge storage tank was dehydrated the next day, the deodorizing effect was maintained. Further, no odorous gas was generated from the cake even in the cake unloading operation two days later. Such a sludge deodorant of the present invention has a very good sustaining effect, and can prevent generation of odor around the dehydrator.

Comparative Examples 25 and 26 An oxidizing agent and a metal salt were used alone as a deodorizing agent, and the other conditions were carried out in the same manner as in Example 19.
It is shown in the table. Until 2 hours after the start of dehydration, no odor was generated in the sludge storage tank or dehydrator, but after that, a bad odor was generated and became odorous.

Also, the cake hopper could not be deodorized. When the sludge remaining in the sludge storage tank was dehydrated the next day, the deodorizing effect was lost, and high concentrations of hydrogen sulfide and methyl mercaptan were generated. Two days later, when the cake was discharged, the odorous gas from the cake was filled, and very high concentrations of hydrogen sulfide and methyl mercaptan were detected.

[Effect of the Invention] The sludge deodorizing agent of the present invention has a high persistence of the deodorizing effect, and it is possible to deodorize the entire sludge dewatering equipment only by adding the present agent to the sludge, thereby significantly improving the environment. it can.

[Brief description of the drawings]

FIG. 1 is a flow sheet of a sewage treatment plant, and a dotted line indicates a sludge dewatering facility.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 11/00-11/20 B01J 20/22 A61L 9/01

Claims (1)

(57) [Claims] 1. A sludge deodorant comprising a water-soluble zinc compound, an organic water-soluble rot inhibitor and water.