JPS60220200A - Treatment of organic sludge - Google Patents

Abstract

PURPOSE:To enable energy conserving treatment, by preparatorily drying the dehydrated cake of org. sludge by utilizing heat at the time of incineration and mixing dehydrated excretion in the dried cake while passing air emitted from an aeration blower through the resulting mixture to dry the same. CONSTITUTION:Excessive sludge 1 generated from a biological treatment process of excretion receives the addition of a cationic polymer and dehydrated to be converted to a dehydrated cake with water content of 80%. This dehydrated cake is guided to a preparatory dryer 4 to be converted to a preparatorily dried substance with water content on the order of 50%. The excretion residue 6 removed and recovered from sewage is dehydrated mechanically to obtain a dehydrated excretion residue 8 which is, in turn, mixed with the preparatorily dried substance 5 while the resulting mixture is received in an aeration dryer 9 and air 11 emitted from an aeration blower 10 used in the biological treatment process of excretion is blown into said mixture to convert the same to a dried product 13 with water content of 10-20%. This product 13 is incinerated or thermally decomposed by an incinerator 14 and the generated heat is supplied to the heat source of the preparatory dryer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an energy-saving method for treating organic sludge generated during the treatment of human waste, sewage, and other organic wastewater.

[Prior art]

Conventionally, organic sludge generated in the treatment of human waste, sewage, and other organic sewage has been dewatered mechanically with the addition of various dehydration aids such as cationic polymers, but the moisture content of the dehydrated cake is still high, making it particularly difficult. In the case of dewaterable sludge, the moisture content of the dehydrated cake is often as high as 80%. In the past, such dehydrated cakes were difficult to dispose of as they were, so they were often dried and incinerated. however.

Drying and incineration require a large amount of valuable fuel.
This is a big problem from the standpoint of energy conservation.

[Problems to be Solved by the Invention] The present invention aims at drying and incinerating the dehydrated cake of organic sludge that is inevitably generated in the treatment of organic sewage. We are developing an extremely energy-saving treatment method that makes the most effective use of paper, hair, and other residues contained in wastewater, eliminates the need for valuable fuels such as heavy oil, and is self-sufficient in energy within the treatment system. This is what we provide.

[Failure to solve the problem]

In the present invention, after pre-drying a dehydrated cake of organic sludge generated in organic sewage treatment, the sludge collected in the organic sewage treatment is mixed, and the mixture is aerated to be used in the organic sewage treatment. It is characterized by drying by blowing air discharged from a blower, incinerating or thermally decomposing at least a part of the obtained dried product, and using the generated heat for pre-drying the dehydrated cake. Embodiment] An embodiment of the present invention will be described with reference to the drawings, taking as an example the application of the present invention to human waste treatment.Excess sludge 1 generated from a human waste biological treatment process (not shown) is.

After the cationic polymer and the like are added, it is dehydrated using, for example, a belt press dehydrator 2 to form a dehydrated cake 6 with a water content of about 80 to 85 cm.This dehydrated cake 6 is led to a pre-dryer 4 and has a water content of about 50 cm. The pre-dried product 5 is obtained by pre-drying until the pre-dried product 5 is obtained. On the other hand, sludge 1 is collected by the screen (not shown) in the pretreatment process of the human waste treatment facility, and sludge 6 is 1
For example, it is dehydrated by a screw press dehydrator 7, resulting in a dehydrated residue 8 having a water content of 60 to 65%.

Next, the pre-dried material 5 of the excess sludge 1 and the dehydrated residue 80 are mixed and stored in the ventilation dryer 9.

The discharge air 11 of the aeration blower 10 that supplies aeration air to the biological treatment process of human waste is blown into the mixture 12, and the mixture 12 is dried through ventilation. Since the discharged air 11 of the aeration blower 10 exhibits a temperature of about 70° C. due to the heat of adiabatic compression, the mixture 12 of the pre-dried material 5 and the dehydrated residue 8 in the aeration dryer 9 is effectively (dried and has a moisture content of 10 The dry product 16 is about ~20%.

Mixture 1 of pre-dried material 5 and dehydrated residue 8 in ventilation dryer 9
2 is air-dried by the discharged air 11 of the aeration blower 10, it is effective to form a vertically elongated packed bed as shown in the figure. That is, since the pre-dried material 5 is mixed with the dehydrated residue 8 whose main component is fiber to form a packed layer,
There is no adhesion or stagnation of the items to be dried, and good ventilation is ensured.

Also, even if the packed bed thickness is high, there is little consolidation.

This has the important effect of preventing the materials to be dried from sticking to each other in the lower part of the packed bed.

As a result, the contact time between the discharge air 11 of the aeration blower 10 and the object to be dried can be increased, and efficient drying can be performed.

Note that, like the discharge air 11 of the aeration blower 10.

In order to perform effective drying using low temperature difference energy having a temperature of only 100°C or less, it is necessary to adjust the physical properties of the material to be dried input to the ventilation dryer 9 as described above, and to adjust the layer thickness. It is important to form a thick packed layer.

In this way, the moisture content is 10 to 2 in the ventilation dryer 9.
A part or the entire amount of the dried product 16 that has been dried to 0% and becomes natural is supplied to the incinerator (or pyrolysis furnace) 14 and incinerated or pyrolyzed, and the generated heat 15 (oil obtained by pyrolysis) is , gas, and heat generated when char is combusted) is supplied as a drying heat source to the pre-dryer 4. In this way, the heat source necessary for each drying process can be self-sufficient, and there is no need to supply fuel such as heavy oil from outside the system.

In the figure, 16 is the combustion air to the incinerator (or pyrolysis furnace) 14, 17 is the residue, 18 is the dry exhaust gas flowing out from the pre-dryer 4, and 19 is the aeration air flowing out from the ventilation dryer 9. Air is supplied to an aeration tank (not shown) in a biological treatment process for human waste.

Further, as the preliminary dryer 4, the most suitable type of dryer for carrying out the present invention is a five-row granulation dryer that simultaneously performs granulation and drying. That is, if the pre-dried product 5 of the dehydrated cake 6 of the present invention is granular, it is possible to form a packed bed with extremely good air permeability in the ventilation dryer 9, so that ventilation drying by the discharge air 11 of the aeration blower 10 is extremely effective. It was done on.

This is also because the step of crushing the dehydrated cake 6 becomes unnecessary.

〔Effect of the invention〕

As described above, the present invention has the following important effects.

■ Since the organic sludge drying process is divided into two stages, dehydrated cakes with a high water content of 80% or more can be dried, incinerated or thermally decomposed in a rational and energy-saving manner.

(Li) The residue obtained by mechanically dehydrating the residue removed and collected from the waste water is mixed with the pre-dried dehydrated cake.

Since ventilation drying is performed using the air discharged from the aeration blower, even if a long packed layer is formed during one ventilation drying, there is no settling or compaction of the material to be dried, and good ventilation conditions can be ensured. The amount of heat retained in the air discharged from the aeration blower, which cannot be said to be large, can be efficiently recovered.

[Brief explanation of the drawing]

The drawing is a system explanatory diagram showing an embodiment of the present invention. 1... Surplus sludge, 2... Belt press dehydrator, 6.
... Dehydrated cake, 4... Pre-dryer, 5... Pre-dried product, 6... Residue, 7... Screw press dehydrator. 8... Dehydrated residue, 9... Ventilation dryer, 10... Aeration blower, 11... Discharged air, 12... Mixture, 1
6...Dried product, 14...Incinerator, 15...Generation heat, 16...Combustion air, 17...Residual liquid, 18...
・Dry exhaust gas. 19... Air for aeration. Patent applicant: Patent attorney representing Ebara Infilco Co., Ltd.
Masayuki Takagi

Claims (1)

[Claims] 1. After pre-drying the dehydrated cake of organic sludge generated in the organic sewage treatment,
・Mix the collected residue, dry the mixture by aerating the discharge air of the aeration blower used for the organic sewage treatment, and incinerate or thermally decompose at least a part of the obtained dried product. A method for treating organic sludge, characterized in that the generated heat is used for preliminary drying of the dehydrated cake. 2. The method for treating organic sludge according to claim 1, wherein the preliminary drying is granulation drying in which granulation and drying are performed simultaneously. 3. The organic sludge treatment method according to claim 1 or 2, wherein a packed bed of the mixture is formed when the mixture is aerated and dried.