JPH072588A - Treatment of sludge - Google Patents

Abstract

PURPOSE:To enable efficient and economical treatment of dehydrated sludge cake and enable the reutilization of thermal energy and treated product and the saving of resources and energy by dividing dehydrated sludge cake into a part for incineration treatment and a part for composting treatment and properly combining both treatments. CONSTITUTION:Dehydrated sludge cake discharged from a sewage disposal plant 1 is divided into a part to be supplied to an incineration facility and a part to be supplied to a composting facility installed in the same plant site or in an adjacent site. Dehydrated cake of polymer- treated sludge having a water content of 80-90% is mainly incinerated and dehydrated cake of lime-treated sludge having a water-content of 60-70% is adjusted to a water content of about 50% and supplied to the composting facility or incinerated as necessary. The cake for incineration treatment is thrown into an incineration furnace 2 and incinerated at >=700 deg.C. The cake for composting treatment is adjusted to a water content of 50-60% by adding incineration ash 4 generated in the incineration furnace 2, etc., to a water-content controlling agent. The incineration heat generated by incineration is supplied to the composting facility 3 and used as a fermentation heat source. The fermented material is reused as an organic fertilizer and the exhaust gas generated by the fermentation process is supplied to the incineration furnace 2 and incinerated together with the sludge to completely eliminate the odor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge treatment method, and more particularly to a sludge treatment method which enables not only efficient treatment of sludge but also effective reuse of substances produced as a result of the treatment. .

[0002]

2. Description of the Related Art Sludge is inevitably generated in the process of treating sewerage water containing household wastewater and manure, but this sludge becomes a huge amount, and the treatment is problematic especially in sewage treatment facilities in large cities. Has become.

As a method for treating this sludge, there are mainly carried out two methods: an incineration treatment in which a sludge dewatering cake obtained by dehydrating sludge is incinerated in an incinerator, and a compost treatment in which a sludge is fermented in a compost facility to be converted into an organic fertilizer. There is.

[0004]

Although the incineration process of incinerating sludge dewatering cake at high temperature is mainly carried out in a treatment facility in a big city, a large amount of this sludge containing a large amount of water is incinerated. It has a drawback that it requires heat energy and processing cost including fuel cost. In addition, there is a possibility that NOx may be emitted by incineration, which is a problem in terms of preventing air pollution. Furthermore, how to treat a large amount of ash produced by incineration has been a problem.

On the other hand, the composting process decomposes sludge dewatered cake into organic fertilizer by the action of bacteria, and is an ideal treatment method considering the global environment, but it takes a long time and a large area. It was necessary in the treatment facility, and it was impossible in reality to install it in the city.
Further, in this composting process, ammonia gas or hydrogen sulfide gas may be generated in a small amount during fermentation, which causes a bad odor. Also, in the past, this 2
There is no supplemental relationship between the schemes, and there is no relationship between them,
The treatment was carried out separately.

As a result of intensive studies on the sludge treatment method, the present inventor succeeded in developing a new treatment method capable of efficiently treating sludge with a small amount of energy by combining both methods. This is what we propose here.

[0007]

According to the present invention, sludge dewatering cake discharged from a sewerage treatment facility or the like is sorted into incineration treatment and composting treatment, and the sludge dewatering cake for incineration treatment is performed at a high temperature of 700 ° C or higher in an incinerator. The sludge dewatering cake for composting is incinerated, and after adjusting the water content, it is fermented and composted in a composting facility.
The incineration heat generated in the incineration process is sent to the compost facility as a heat source for fermentation, and the incinerated ash is also supplied to the sludge dewatering cake in the compost facility to be reused as a moisture adjuster, if necessary. The odor generated during fermentation in a composting facility is sent to an incinerator where it is burned for deodorization and the substance after fermentation is reused as an organic fertilizer to solve the above problems.

[0008]

[Function] The incineration ash produced during the incineration process is added to the sludge dewatering cake for moisture treatment as a water content adjusting agent, and the water content is Used to adjust. or,
Similarly, the incineration heat generated during the incineration process is sent to the compost facility and used as a heat source for fermentation. On the other hand, exhaust gas containing ammonia odor and hydrogen sulfide odor generated in the fermentation process of sludge dewatering cake in the compost facility is sent to the incineration facility where it is completely burned and deodorized. Then, the substance of which fermentation has been completed in the compost facility is reused as an organic fertilizer.

As described above, this sludge treatment method is carried out by using incineration treatment and composting treatment in combination, and the product in the treatment process is effectively used as a heat energy source or a regulator to improve treatment efficiency. In addition, the ratio of incineration treatment and composting treatment can be appropriately changed according to the demand trend of organic fertilizer and the required amount of sludge treatment, and the most efficient treatment can be flexibly implemented.

[0010]

The present invention will be described in more detail with reference to the drawings. The sludge dewatering cake sent from the sewerage treatment facilities of each municipality is sorted for incineration and composting and sent to each treatment facility. Both treatment facilities are preferably installed on the same site or adjacent to each other. The sludge for incineration treatment and composting is exactly the same as the sludge itself, and it is not divided according to the properties and composition of the sludge, but the demand trend and treatment amount of the organic fertilizer finally produced by the method of the present invention. It is decided in consideration of the number of items.

That is, when a large amount of sludge has to be treated in a short period of time such as in winter when the organic fertilizer is not needed, the sludge dewatering cake is sent to the incinerator to give more sludge dewatering cake by giving priority to the treatment efficiency. When demand is high, send more sludge dewatering cake to composting.

The sludge dewatering cake includes a polymer-treated sludge dewatering cake in which a polymer flocculant is added to sludge and a lime-treated sludge dewatering cake in which lime is added to sludge. It has a high water content of 90%, and fermentation cannot be started by itself. Fermentation becomes possible only by adjusting the water content and mixing with lime-treated sludge dehydrated cake. Therefore, it is mainly sent to the incineration process. On the other hand, the lime-treated sludge dewatering cake is obtained by adding lime to sludge and has a water content of 60 to 70%, and if the water content is adjusted to about 50% and the temperature is adjusted to an appropriate temperature, it itself. Since fermentation is started, it is mainly used for composting, but since it can be incinerated, it is also used for incineration if necessary. The sludge dewatering cake for incineration treatment is put into the incinerator 2 of the incineration facility and incinerated at a high temperature of 700 ° C or higher. The reason for incineration at a high temperature of 700 ° C. or higher is that NOx is produced and an offensive odor is generated at the time of incineration below this, and the production of NOx and the offensive odor are prevented at 700 ° C. or above.

On the other hand, the sludge dewatering cake distributed to the composting treatment is added with incineration ash 4 and the like generated along with the sludge incineration in the incinerator 2 as a water content adjusting agent, and the optimum moisture content for starting fermentation is 50 to 60%. It will be adjusted to the front and back. The incineration heat generated during the incineration is sent to the compost facility 3 and used as a heat source for fermentation. That is, the compost facility 3 is supplied with the heat source and the moisture conditioner from the incinerator 2.

Thus, in the compost facility 3, the incinerator 2 is
Fermentation of sludge dewatering cake is carried out with assistance from the company, and the substance after fermentation is reused as organic fertilizer. Exhaust gas containing a foul odor generated in the fermentation process is sent to the incinerator 2 where it is completely burned at high temperature together with sludge to be deodorized. The malodor produced during the fermentation process is due to ammonia gas or hydrogen sulfide gas, and it is possible to completely deodorize by burning these at high temperature.

[0015]

EFFECT OF THE INVENTION The sludge treatment method according to the present invention has the constitution as described above, and is carried out by combining the incineration treatment and the composting treatment. Implementing the most efficient and economical treatment by appropriately and flexibly changing the proportion of sludge to be distributed between incineration and composting, taking into consideration sludge volume, demand trends for organic fertilizers produced in the treatment process, etc. be able to.

Further, the heat energy and products produced in the treatment process can be reused, and it has an excellent effect from the viewpoint of resource saving and energy saving.

[0017]

[Brief description of drawings]

FIG. 1 is a flowchart of an embodiment of a sludge treatment method according to the present invention.

[Explanation of symbols]

 1 Sewer treatment facility 2 Incinerator 3 Composting facility 4 Incinerator ash

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C02F 11/06 ZAB A 7446-4D

Claims (3)

[Claims] 1. Sludge dewatering cake discharged from a sewerage treatment facility is sorted into incineration and composting, and the sludge dewatering cake for incineration is incinerated at a high temperature of 700 ° C. or higher in an incinerator, while for composting. Sludge dewatering cake is fermented in a composting facility after water content adjustment to be composted, and the incineration heat generated in the incineration process is sent to the composting facility as a heat source for fermentation, and incineration ash is also required. It is supplied to the sludge dewatering cake in the compost facility and reused as a moisture conditioner, and the odor generated during fermentation in the compost facility is sent to the incinerator where it is burned to deodorize and the substance after fermentation is completed as organic fertilizer. A sludge treatment method characterized by being reused. 2. The sludge treatment method according to claim 1, wherein the incineration facility and the compost facility are installed on the same site. 3. The method for treating sludge according to claim 1, wherein the incineration facility and the compost facility are installed adjacent to each other.