JPH07246398A - Method for caking sewage dehydrated sludge - Google Patents

Abstract

PURPOSE:To cake a sewage dehydrated sludge while preventing the elution of various harmful materials and without incresing the treating amt. and the reclamation amt. CONSTITUTION:Incinerated ash zeolite obtained from sewage sludge incinerated ash, cement and water are added to a sewage dehydrated sludge, kneaded and then cured to form a cake. The indinerated ash zeolite is hydrothermally synthsized by mixing the incinerated ash with an aq. soln. of an alkali metal hydroxide such as NaOH and heating the mixture. Sewage sludge incinerated ash or the molten slag of sewage sludge incinerated ash can be added as well as the incinerated ash zeolite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying sewage dewatering sludge, which can form a stable solidified product which does not emit harmful substances out of the system such as sewage dewatering sludge generated from a sewage treatment plant. Is.

[0002]

2. Description of the Related Art As a method of treating a large amount of sewage sludge generated from a sewage treatment plant, incineration ash obtained by incineration and reducing the volume of sewage dewatered sludge is mixed with cement into sewage sludge and landfilled as a property similar to inorganic soil. The method is known. As a method for treating industrial waste containing heavy metal compounds such as cyanide and hexavalent chromium, a method is known in which cement, natural zeolite, and water are kneaded with waste sludge and solidified.

However, the former method has some effect in preventing the elution of heavy metal compounds, ammonia nitrogen, phosphorus, etc., but is not so effective in preventing the elution of organic substances, etc., which are COD-causing substances. For this reason, landfill disposal may eutrophicate nearby waters and cause red tides.
Although the latter method has the effect of preventing the leakage of heavy metal compounds and odors, since a large amount of natural zeolite is brought in from outside the system, the treatment amount increases, the treatment equipment becomes larger, and the landfill amount also increases. There are drawbacks.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and solves the problems of heavy metal compounds, ammonia nitrogen,
The object of the present invention is to provide a method for solidifying sewage dewatered sludge that can prevent the elution of phosphorus, organic substances, COD-causing substances, and the like, and that does not increase the treatment amount or landfill amount.

[0005]

In order to solve the above-mentioned problems, the invention of claim 1 is one in which incineration ash zeolite made from sewage sludge incinerator ash and cement are added to sewage dehydrated sludge. It is characterized in that it is solidified by curing after kneading. Claim 2
The invention of, with respect to sewage dewatered sludge and sewage sludge incineration ash, after adding and kneading incineration ash zeolite and cement using sewage sludge incineration ash as a raw material, characterized by curing to a solidified product To do. Furthermore, the invention of claim 3 is the curing after sewage dewatered sludge, sewage sludge incineration ash, and sewage sludge incineration ash molten slag are kneaded by adding incineration ash zeolite and cement made from sewage sludge incineration ash as a raw material. It is characterized in that it is made into a solidified product. In any case, water can be added and kneaded as needed, and after kneading by adding incinerated ash zeolite, cement, and water, the incinerated ash zeolite is re-kneaded and cured. You can also take In addition, as shown in the examples, the amount of incinerated ash zeolite added depends on the weight of the solidified matter.
It is preferably 20 to 50%.

[0006]

The present invention is characterized in that incineration ash zeolite made from sewage dewatered sludge incineration ash and cement are added to sewage dewatered sludge and the like. This incinerated ash zeolite is produced by mixing incinerated ash with an aqueous solution of an alkali metal hydroxide such as NaOH, heating and hydrothermally synthesizing the ash.
It has a base substitution capacity (CEC value) equal to or higher than that of natural zeolite. When this incinerated ash zeolite is added to sewage dewatered sludge along with cement, it absorbs heavy metal compounds, ammonia nitrogen, phosphorus, organic substances, COD-causing substances, etc. in sewage dewatered sludge, and the system is formed from the solidified product solidified by cement. It is possible to prevent these harmful substances from being eluted to the outside. Moreover, unlike natural zeolite, in the present invention, since incineration ash zeolite made from sewage sludge incineration ash is used, the total treatment amount and landfill amount do not increase. The flow of the present invention is shown in FIG.

[0007]

[Example 1] First, to 100 parts by weight of dehydrated sewage dewatered sludge generated from a sewage treatment plant, 15 parts by weight of cement for sludge solidification and 30 parts by weight of incinerated ash of dewatered sludge were added. Then, it was kneaded with water and cured. Separately from this, 80 g / l of sewage dewatered sludge incineration ash 36 parts by weight
181 parts by weight of NaOH was added and heated at 90 ° C. for 7 hours to synthesize zeolite to obtain incinerated ash zeolite. 5 g of this incinerated ash zeolite was added to 20 g of the above-mentioned aquatic organism, re-kneaded, and cured to obtain a solidified product. This was designated as Sample 1.
The amount of incinerated ash zeolite added in Sample 1 was 20% of the weight of the solidified product.

Next, 15 g of incinerated ash zeolite was added to 20 g of the above-mentioned aquatic organism, re-kneaded and aged to obtain a solidified product. This was designated as Sample 2. The amount of incinerated ash zeolite added in Sample 2 was 43% of the weight of the solidified product. Further, for comparison, the above kneaded product containing no incinerated ash zeolite was designated as Sample 3. The amount of incinerated ash zeolite added is 0%.

100 mL of distilled water for 20 g of each of these samples
Was added and the mixture was stirred for 6 hours, and the eluate was centrifuged to obtain supernatant water. The NH ₄ ⁺ concentration in this supernatant water was measured and found to be 14.1 mg / l for sample 1 and 9.0 for sample 2.
Although it was mg / l, sample 3 containing no incinerated ash zeolite
Was 15.8 mg / l. As a result, NH
It can be seen that the dissolution rate of ₄ ⁺ is 11% and that of sample 2 is 43%.

[Example 2] Samples 4 and 5 were obtained by adding incinerated ash, cement, incinerated ash zeolite, etc. to the sewage dewatered sludge as shown in Table 1 and mixing and stirring. As a result of performing an elution test on Sample 4 and Sample 5 together with Sample 3 which is a comparative example, the results shown in Table 2 were obtained. It can be seen that all have excellent elution prevention. The elution prevention effect was calculated based on the elution amount of Sample 3.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

As described above, according to the method for solidifying sewage dewatered sludge of the present invention, the addition of incinerated ash zeolite can remove heavy metal compounds, ammonia nitrogen, phosphorus, COD-causing substances, etc. in the solidified product. Since they can be adsorbed and their elution can be prevented, it is possible to prevent leakage of harmful substances to the outside of the system after the solidified material is filled up. Moreover, since this incinerated ash zeolite is synthesized by using sewage dewatered sludge incinerated ash as a raw material, there is an advantage that the total treatment amount and landfill amount are not increased. Therefore, the present invention is of great value as a method for solidifying sewage dewatered sludge that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a flow chart of the present invention.

Claims (6)

[Claims] 1. A sewage dewatered sludge, which is obtained by adding incineration ash zeolite and sewage sludge incinerated ash as a raw material to sewage dewatered sludge, kneading the mixture, and then curing it to form a solidified product. Solidification treatment method. 2. A sewage dewatered sludge and a sewage sludge incineration ash are mixed with incineration ash zeolite and cement made from sewage sludge incineration ash as a raw material, kneaded, and then cured to form a solidified product. A method for solidifying sewage dehydrated sludge. 3. The sewage dewatered sludge, the sewage sludge incineration ash, and the sewage sludge incineration ash molten slag are mixed with incineration ash zeolite and cement made from sewage sludge incineration ash as raw materials, and then cured. A method for solidifying sewage dewatered sludge, which is characterized in that it is a solidified product. 4. The method for solidifying sewage dewatered sludge according to claim 1, wherein water is added and kneaded. 5. The method for solidifying sewage dewatered sludge according to claim 1, wherein the amount of the incinerated ash zeolite added is 20 to 50% of the weight of the solidified product. 6. A method for solidifying sewage dehydrated sludge, which comprises re-kneading and curing the solidified product obtained by the method according to claim 1 and incinerated ash zeolite.