JPS59206099A - Process for dehydrating and drying organic sludge - Google Patents

Abstract

PURPOSE:To reduce remarkably the heat necessitated in a drying stage by supplying ejected air from an aeration blower to a drying stage of dehydrated cake obtd. by the treatment of org. sludge and supplying the air passed through the drying stage to an aeration stage. CONSTITUTION:After adding dehydration aid 10 such as cationic polymer, fibrous material, etc. to org. sludge 1 such as sewage, etc., the sludge is dehydrated with a screw press 2 and separated into dehydrated cake 7 and separated water 11. The discharge port 3 of the dehydrated cake of the screw press 2 is connected to an opening part of the wall of an enclosed type drier 4 via a duct 5 or directly. Accordingly, the dehydrated cake 7 is transferred automatically to the dryer 4. Ejected air 6 from an air blower 12 is supplied to the inside of the dryer 4. Further, a duct 8 is provided for transferring the air at the other end of the dryer 4. Another end of the duct 8 is inserted into an aeration tank 13 for a treating stage of activated sludge, etc. in the sewage treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy-saving dehydration drying method for organic sludge.

Conventionally, organic sludge such as sewage sludge is often dehydrated using a mechanical dehydrator and then dried, but the drying process requires a large amount of fuel such as heavy oil, which requires a huge amount of energy. The current situation is that we are consuming .

The object of the present invention is to fundamentally solve these drawbacks and to provide a process that allows the drying step to be carried out at substantially no cost and to achieve significant energy savings.

The present invention connects the discharge end of the dewatering process of a screw press and the drying process directly or via a pipe, and after dewatering the sludge in the dewatering process of the screw press, it is guided to the drying/exposure process, and the drying process Dehydration and drying of organic sludge, characterized in that the discharge air of an aeration blower is allowed to flow into the dehydration cake, and the dehydration cake is dried by the retained heat of the discharge air, and the air flowing out from the drying process is supplied and used for one aeration process. It's a method.

Embodiments of the present invention will be described below with reference to the drawings.

Organic sludge 1 such as sewage sludge is added with dehydration aids 1o such as cationic polymers and sludge to improve its dehydration properties, and then dehydrated in a screw press 2 to form a dehydrated cake 7 and dehydrated separated water 11. separated into The dehydrated cake discharge port 3 of the screw press 2 is directly connected to the opening in the wall of the closed dryer 4 via a pipe 5, and the dehydrated cake 7 automatically flows into the dryer 4. .

The air 6 discharged from the air blower 12 is supplied into the dryer 4 . Further, at the other end of the dryer 4, a conduit 8 for air outflow is provided. The other end of the pipe 8 is inserted into an aeration tank 13 used in an activated sludge treatment process in sewage treatment.

Conventionally, aeration blowers have been used only for dissolving oxygen in water and stirring the air in the aeration tank, but the inventor of the present invention discovered that the discharge air of the aeration blower is smaller than the intake air, as is clear from the adiabatic compression theory of gases. By noting that the temperature of the dehydrated cake increases significantly, reaching 70 to 80°C, they were able to come up with a new idea that had never been seen before: drying the dehydrated cake using the air discharged from the aeration blower.

Therefore, the holding pressure of the air discharged from the aeration blower in the dryer 4 (usually 0.7 kfi/cn, although it is related to the water depth of the aeration tank)
! However, the present inventor discovered that the space between the screws is filled with sludge near the dewatered cake discharge section of a screw press, and that approximately 10kgf/cI! Focusing on the above-mentioned pressure, we found a rational method for supplying dehydrated cake.

That is, the present invention uses a centrifugal dewatering machine as a sludge dehydrating model.
(Like a rotary press, filter press, vacuum dehydrator,
One of the features is that we did not use a type that makes it difficult to take out dehydrated cake under pressure, but rather used a screw press instead, and combined the screw press's dehydrated cake outlet with a dryer. This method has the important advantage that the sludge dewatering cake can be fed to the dryer under pressure in a rational manner, without the risk of leakage of the pressurized air inside the dryer to the outside.

Thus, the dehydrated cake 7' supplied into the dryer 4 comes into direct contact with the discharged air 6 and is dried by the heat retained therein.
The dry matter is discharged from the dry matter discharge port 14.

On the other hand, the air which has been heated to the dehydrated cake 7' and whose temperature has dropped is supplied to the aeration tank 13 through the pipe 8 and diffused therein, and is used for oxygen supply and stirring in the aeration tank.

Note that if the amount of dust generated during drying is small, air may be supplied directly into the aeration tank 13, but it is also preferable to attach a dust remover such as a cyclone to the pipe line 8. Furthermore, in order to prevent the air diffuser in the aeration tank from becoming clogged with dust, it is preferable to make the aeration diameter as large as possible.

According to the present invention as described above, the following great benefits can be obtained.

■ Dehydrated cake using a screw press can be dried in an extremely energy-saving manner without the need for fuel.

■ Dry matter can be used as fuel. In other words, an energy-saving process of turning sludge into fuel can be realized.

■ By taking advantage of the characteristics of the cake discharge mechanism of the screw press, the ability to supply dehydrated cake to the dryer is streamlined and there is no air leakage.

■ Construction costs can be reduced because there is no need for a conyer to transport the dehydrated cake from the dehydrator to the dryer.

■ Since the malodorous components in the air discharged from the drying process are biologically deodorized by the activated sludge present in large quantities in the aeration tank, no special deodorizing equipment is required.

[Brief explanation of the drawing]

The drawing is a flow sheet illustrating an embodiment of the invention. l... Organic sludge, 2... Bunch, screw press, 3... Dehydrated cake outlet, 4... Bunch, dryer, 5. Old pipe, 6... ...Discharged air, 7.7
'... dehydrated cake, 8... pipe line, 10
...Dehydration aid, 11... Song/dehydration separated water, 12
...Air blower, aeration tank for 13., 14.
...Dry matter outlet.

Claims (1)

[Claims] 1. The discharge end of the dewatering process of the screw press and the drying process are connected directly or through a pipe, and the sludge is dehydrated in the dewatering process of the screw press and then introduced to the drying process, and an aeration blower is added to the drying process. A method for dehydrating and drying organic sludge, characterized in that discharged air is allowed to flow in, the dehydrated cake is dried by the retained heat of the discharged air, and the air flowing out from the drying process is supplied to a sludge process.