JPS60202799A - Treatment of organic sludge - Google Patents

Abstract

PURPOSE:To dry efficiently high water-content dehydrated cake by utilizing the heat retained by the discharged from an aeration blower for supplying air into an aeration vessel wherein organic sewage and sludge are treated, for the finish drying of the cake, and heating the discharged air which is utilized for the predrying of the cake. CONSTITUTION:The dehydrated cake 1 of organic sludge having about 70-80% water content is supplied into a predryer 2, for example, an agitation-granulation dryer, dried by the hot air 3 while being agitated and graulated, and converted into a granular predried material 4 having about 40-65% water content. The predried material 4 is subsequently supplied into a hermetic finish dryer 5 wherein a packed bed 6 is formed. The air 9 discharged from an aeration blower 8 fro supply aeration air into an aeration vessel 7 in the treating system of organic sewage, organic sludge, etc. is passed through said packed bed 6, and the predried material 4 forming the packed bed 6 is dried to obtain a material 10 having <40% water content (normally 20-30%).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an extremely rational method for dewatering cakes of organic sludge generated in the treatment of organic sewage such as sewage, human waste, and various industrial wastewater, and in the treatment of organic sludge. The present invention relates to a method for efficiently and energy-saving processing.

[Prior art]

Organic sludge is generally disposed of by dehydration, drying, and incineration, but the dehydrated cake obtained by dehydration has a moisture content of about 70 to 80%, and is then dried and incinerated. In this case, (1) Drying and incineration of the dehydrated cake requires a large amount of fuel.

■ Dust collection and deodorization treatment of dry exhaust gas or incineration exhaust gas is required.

Since incineration in particular depends on the quality of drying, it is extremely important to determine how effectively and rationally drying can be carried out.

[Purpose of the invention]

The present invention provides a method for treating organic sludge that divides the drying of a dehydrated cake of organic sludge into two stages, pre-drying and final drying, performs each drying process rationally, and solves the above-mentioned conventional problems. The purpose is to

[Structure of the invention]

In the present invention, when a dehydrated cake of organic sludge is pre-dried and then further dried, the retained heat of the discharged air of the aeration blower that supplies air to the taste tank in the treatment of organic sewage, organic sludge, etc. The exhaust air from the final drying is heated with an arbitrary heat source and then used for the preliminary drying, and the exhaust air from the preliminary drying is further supplied to the aeration tank. be.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. A dehydrated cake 1 of organic sludge with a moisture content of about 70 to 80q6 is supplied to a pre-dryer or an agitation granulation dryer, and is agitated and granulated. While drying with hot air 3 described later,
It is converted into a granular pre-dried material 4 having a moisture content of about 40 to 65 inches. This pre-dried material 4 is first supplied to a closed finish dryer 5 to form a packed bed 6, and inside the packed bed 6 is an aeration tank for treating organic sewage, organic sludge, etc. 7
The discharge air 9 of the aeration blower 8 that supplies air for aeration is aerated, and the pre-dried material 4 forming the packed bed 6 is dried to a moisture content of less than 40% (usually about 20 to 60%). Get 10.

In this way, the temperature of the discharge air 9 of the warm air blower 8 vented to the packed bed B in the finishing dryer 5 rises above the temperature of the suction air 11 due to the adiabatic compression of the air, and reaches at least 60 to 70°C. . As a result, a small amount of moisture contained in the pre-dried material is easily removed by the heat capacity of the discharged air 9.

Thus, the exhaust air 12 from the finish dryer 5 is heated by an arbitrary heat source 16, preferably becomes hot air 6 of 300° C. or higher, and is used as a heat source for drying the dehydrated cake 1 in the pre-dryer 2. Since the exhaust air 14 discharged from the pre-dryer 2 is mainly composed of air, it is sent to the aeration tank 7 and used as aeration air for biological treatment of sewage and other organic wastewater 15. .

Further, the exhaust air 14 from the pre-dryer 5 contains dust and odor components, but the dust is collected in the water in the aeration tank 7 and deodorized biologically, so a special dust collection and deodorization device is used. is not necessary.

Note that the heating source 16 of the exhaust air 12 from the finishing dryer
When the incineration equipment 16 is attached, it is convenient to use the combustion exhaust gas from incinerating the dry matter 10 or the incineration heat from incinerating the residue containing paper collected from sewage, human waste, etc. This eliminates the need for valuable fuel such as heavy oil as the heating source 16.

Further, as the pre-dryer 2, the hot air 3 is supplied from the lower part to the supplied dehydrated cake 1 while giving a swirling flow using a stirring blade.

It is most preferred to use a granulation dryer that can carry out drying and granulation operations simultaneously. That is, the pre-dried material 4 discharged from the granulation dryer is a granulated material with a narrow particle size distribution that has been suitably pre-dried to a moisture content of about 50 to 60%, so it was supplied to the finishing dryer 5. Sometimes, a packed bed 6 with very good air permeability can be formed, and even if the packed bed thickness is increased, the particles at the bottom of the layer will not be consolidated, which is an important effect. A relatively small amount of heat contained in the discharged air 9 can be recovered within the packed bed 6 very efficiently.

〔Effect of the invention〕

As described above, according to the present invention, the following extremely important effects can be obtained.

- Since the drying process is divided into two stages, even a dehydrated cake with a high moisture content can be dried rationally and in an energy-saving manner, making subsequent incineration processing advantageous. therefore,
It can also be effectively applied to surplus activated sludge that is difficult to dewater and is generated from biological treatment processes such as sewage and human waste.

■ We used a process configuration in which the dehydrated cake is finished dried using the adiabatic compression heat of relatively low-temperature warm air blower discharge air against a specific material called pre-dried material, which has been pre-dried with high-temperature air. Even with the retained heat of the hot air blower discharge air, which has a small thermal capacity, it is possible to easily obtain a dried product with a moisture content of less than 40 inches.

In other words, if you try to dry a dehydrated cake using only the heat of adiabatic compression from the aeration blower, the amount of heat retained in the air discharged from the aeration blower will be significantly less than the amount of heat required to evaporate the water that should be removed by drying from the dehydrated cake, resulting in a low moisture content. However, the present invention does not have this problem.

■ Special equipment for collecting dust and deodorizing dry exhaust air is no longer required.

■ The air supplied to the aeration tank is the exhaust air flowing out from pre-drying using high-temperature hot air, so its temperature is around 60°C even in winter, so it is possible to lower the water temperature in the aeration tank and use it for biological treatment. There are no problems with adverse effects.

[Brief explanation of the drawing]

The drawing is a system explanatory diagram showing an embodiment of the present invention. j 1... Dehydrated cake, 2... Pre-dryer, 6...
・Hot air, 4... Pre-dried material, 5... Finishing dryer,
6... Filled bed, 7... Aeration tank, 8... Aeration blower, 9... Discharge air, 10... Dry material, 11... Suction air, 12.14... Exhaust air , 16...Heating source, 15...Organic sewage, 16...Incineration equipment. Patent applicant: Patent attorney representing Ebara Infilco Co., Ltd.
Masayuki Takagi

Claims (1)

[Claims] 1. When pre-drying a dehydrated cake of organic sludge and then final drying it, the discharge air of an aeration blower that supplies air to an aeration tank in the treatment of organic sewage, organic sludge, etc. The retained heat is used for the final drying, the exhaust air from the final drying is heated with an arbitrary heat source and then used for the preliminary drying, and the exhaust air from the preliminary drying is further supplied to the aeration tank. A method for treating organic sludge. 2. The method for treating organic sludge according to claim 1, wherein the preliminary drying is granulated and dried, and a packed bed of the granulated dried product is formed during the final drying.