JPH069680B2 - How to deodorize sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to deodorization of sewage sludge, human waste sludge, sludge of a paper mill, etc., which produces a foul odor due to hydrogen sulfide, methyl mercaptan, ammonia, and amines. It is about the method.

[Conventional technology]

Conventionally, the method of using ferric chloride and slaked coal has been used to dehydrate these sludges, but recently, a dehydration method using a belt press has been implemented as an energy-saving type.
In this method, since organic polymers are used for dehydration in a neutral region, the organic matter is quickly decomposed and a large amount of foul odor is generated, which is a problem from the working environment.

As one of the countermeasures, the present inventors have found that by using a polyiron sulfate solution containing trivalent iron as a main component in combination with an organic polymer, it is possible to reduce the water content of the dehydrated cake and to have a deodorizing effect. Found and proposed at the 22nd Sewer Research Presentation (June 1985).

The Tokyo Sewerage Bureau has also announced that hydrogen peroxide is effective for deodorizing sewage sludge.

[Problems to be solved by the invention]

However, these methods have problems that it is necessary to use a large amount of polyiron sulfate and hydrogen peroxide, and the apparatus is corroded by excess hydrogen peroxide. The present inventors have conducted various studies to solve these problems. (1) Trivalent iron is partially reduced to divalent iron in contact with anaerobic sludge, (2) The reduced divalent iron is highly reactive and reacts immediately with sulfides, (3) the deodorizing effect is poor in the absence of trivalent iron, (4) hydrogen peroxide, hypochlorous acid The deodorizing effect is remarkably improved when used in combination with an oxidizing agent such as soda. PH of (lower than pH5),
Causes corrosion to dehydrators. Also, if deodorizing is performed only with an oxidizing agent such as hydrogen peroxide or sodium hypochlorite, a foul-smelling substance 1
It was found that 5 to 10 times the number of moles is required per mole and significant corrosion occurs.

[Means for Solving Problems and Their Actions]

The present invention is based on the above-mentioned findings, and a sludge containing a malodorous substance composed of one or more components of hydrogen sulfide, methyl mercaptan, ammonia and amines is added to an extremely small amount of polyiron sulfate and peroxide. This is a method of deodorizing sludge by adding hydrogen. In the present invention, polyferric sulfate means that trivalent iron in polyiron sulfate partially contacts with a malodorous substance to form divalent iron, which reacts with the malodorous substance to form iron sulfide and divalent iron. Almost nothing is left. For this reason, it is not necessary to adjust the pH to 9 or higher to form iron flocs as in the case where a large amount of divalent iron is used, and the amount of alkali and the amount used is drastically reduced. The amount of polyferric sulfate added is less than the number of moles of the malodorous substance, and about 2/1000 to 5/1000 is necessary and sufficient, and therefore the pH hardly decreases. Especially hydrogen peroxide and 2
The Fenton group is generated in the reaction with valent iron, which decomposes a malodorous substance that is difficult to decompose, thereby further improving the deodorizing effect. The addition amount of hydrogen peroxide used in the present invention is much smaller than that of a malodorous substance, and is 3/1000 to 1/1 in terms of mole number.
00, which is extremely small compared with the conventional deodorizing method in which only hydrogen peroxide is added. Since iron acts as a catalyst in the reaction as described above, the dehydrator and peripheral equipment are hardly oxidized and corroded.

The order of adding the chemicals is preferably such that hydrogen peroxide is added after polyiron sulfate is added, but a method of simultaneously adding may be used.

〔Example〕

A raw sludge containing 3000 ppm hydrogen sulfide and 80 ppm methyl mercaptan in the coagulation sedimentation sludge of a paper mill,
Poly iron sulfate solution _{^{(Fe 3+ 160g /, SO 4}} 2- 375
g / solution) and then hydrogen peroxide (H ₂ O ₂
Table 1 shows the results of deodorization treatment by adding 30% solution) and the results of deodorization treatment by the conventional method.

[Effects of the Invention] The present invention is a deodorizing method in which polyiron sulfate and hydrogen peroxide are added to sludge in combination, but the addition amount thereof is remarkably higher than that in the method using polyiron sulfate and hydrogen peroxide alone. The malodorous component can be removed by reducing the amount.

Further, since the addition amount is small, the pH drop of sludge and the corrosion of the equipment due to excess hydrogen peroxide are significantly reduced, and the practical effect thereof is great.

Claims (1)

[Claims] 1. A sludge containing a malodorous substance composed of one or more components of hydrogen sulfide, methyl mercaptan, ammonia and amines, is contained in an amount of 2/1000 mol to 5/1000 mol / mol of the malodorous substance. 1000 moles of polyiron sulfate and 3
/ 1000 mol to 10/1000 mol of hydrogen peroxide under superoxide is added, and a sludge and a deodorizing method.