JPH0375240B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an energy-saving method for treating water-containing materials such as sludge and sludge generated during the treatment of human waste, sewage, and other organic wastewater. It is.

[Prior art]

Conventionally, water-containing materials such as human waste, sewage, and other organic wastewater are dehydrated using mechanical dehydrators such as belt presses and centrifugal dehydrators, but the moisture content is still high. , must be dried before processing and disposal.

In particular, surplus activated sludge and pseudo-sedimented sludge are mixed and then mechanically dewatered with the addition of a dewatering aid such as a cationic polymer.
The biggest problem is that the drying process requires a large amount of valuable fuel, which increases the burden of maintenance and management costs for treatment facilities.

However, in order to smoothly dispose of the water-containing substances that are inevitably generated in organic wastewater treatment, the above problems were considered to be unavoidable, but rational energy-saving drying methods have not been developed. Development is desperately needed.

[Purpose of the invention]

The present invention is based on the novel technical concept of converting paper, hair, and other residues contained in organic sewage, which have never been used in the past, into fuel and using this for drying sludge. It is an object of the present invention to provide a treatment method that can treat these water-containing substances in a completely fuel-free and extremely energy-saving manner, and can fully satisfy the demands in the field.

[Structure of the invention]

The present invention mechanically dehydrates residue generated in organic sewage treatment, and dries the obtained dehydrated residue using the retained heat of the air discharged from an aeration blower used in the organic sewage treatment. Incinerate the residue,
The present invention is characterized in that the heat generated by combustion during the incineration is utilized for drying the sludge generated during the organic sewage treatment.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. After passing through a crusher (not shown), human waste 1 brought in by a vacuum truck or the like is passed through a fine mesh screen 2 into a toilet in the human waste. The human waste 7 such as paper, hair, and cotton is removed, and the removed human waste 3 is supplied to a biological treatment process such as a biological nitrification and deoxidation process consisting of an aeration tank 4 and a settling tank 5, etc., and then treated. It flows out as biologically treated water 6. On the other hand, the moisture content removed and recovered by screen 2
The residue 7, which is about 95%, is dehydrated to a water content of 50 to 55% by a screw press dehydrator or other dehydrator 8 to become a dehydrated residue 9.

Next, the dehydrated residue 9 is stored in a closed type ventilation dryer 10.
is supplied to form a filling layer 11, and this filling layer 1
1, the discharge air 13 of the aeration blower 12 that supplies aeration air to the aeration tank 4 is vented, and the discharged air 14 is supplied to the aeration tank 4.

The temperature of the air 13 discharged from the aeration blower 12 rises to 60 to 80°C due to the adiabatic compression effect of the air. 9 is effectively dried;
It dries to a residue 15 with a moisture content of 10% or less, which is turned into solid fuel. That is, since the dehydrated residue 9 is mainly composed of fibers, the packed layer 1 is placed in the ventilation dryer 10.
1, mutual adhesion like sludge,
Since there is almost no consolidation phenomenon, it is possible to ensure good air permeability, and since the moisture content is lower than that of a dehydrated sludge cake, the amount of heat required to dehydrate and dry the residue 9 is lower than that of a high moisture sludge dehydrated cake. Much less heat is needed than the amount of heat required to dry the
The air 13 discharged from the aeration blower 12, which has a considerably small amount of heat, can effectively dry the fuel and turn it into solid fuel.

In addition, the activated sludge precipitated in the sedimentation tank 5 of the biological treatment process is used as return sludge 16 in the biological treatment process, and the surplus activated sludge 17 is dehydrated with various mechanical dehydrators 18 such as a centrifugal dehydrator and a belt press.
A dehydrated cake 19 with a water content of about 80% is formed and is supplied to a sludge dryer 20. The dehydrated cake 19 is dried in the sludge dryer 20 without using valuable fuel such as heavy oil, and the above-mentioned dried residue 15 is used as solid fuel to be self-combusted by introducing combustion air 22 into the incinerator 21. The generated gas 23 is supplied to the sludge dryer 20 and used as a heat source for drying. At this time, the temperature of the combustion generated gas 23 in the incinerator 21 is about 600 to 800°C, and the amount of heat it possesses is sufficient to dry the dehydrated cake 19 with a moisture content of 80% to a moisture content of 40% or less. confirmed.

The dried sludge 24 dried in the sludge dryer 20 in this way is stored in the storage tank 25, but if a part 24' of this dried sludge 24 is supplied to the incinerator 21, dried, and co-incinerated with the residue 15. , combustion generated gas 23
Since the retained heat amount can be greatly increased, the dehydrated sludge cake 19 can be dried to a moisture content of about 10 to 20%.

Note that the dried exhaust gas 26 from the sludge dryer 20 and the incineration residue 27 from the incinerator 21 are discharged to the outside of the system.

〔Effect of the invention〕

As described above, according to the present invention, the following remarkable beneficial effects can be obtained.

The process of drying the sludge dewatering cake, which conventionally required a large amount of fuel consumption, has been significantly streamlined and becomes unnecessary.

The dehydrated residue obtained by mechanically dehydrating the residue removed and collected from wastewater is dried with the discharge air of an aeration blower, so there is no sludge-like buildup, large clumps, compaction, or stickiness in the dryer. Good ventilation conditions can be ensured, and the moisture content of the dehydrated residue is in the 50% range, which is much lower than the moisture content of dehydrated sludge (about 80%), so it has a large amount of heat. Due to the heat content of the air discharged from the aeration blower, drying can be carried out to a sufficiently low moisture content, and the residue can also be used as fuel.

By using the residue that originally existed in the sewage as a heat source for drying the sludge generated during sewage treatment, there is no need to input resources such as heavy oil from outside, and it can be used within the sewage treatment process system. can be self-sufficient.

[Brief explanation of drawings]

The drawing is a system explanatory diagram showing an embodiment of the present invention. 1... Human waste, 2... Screen, 3... Sludge removed human waste, 4
... Aeration tank, 5... Sedimentation tank, 6... Biological treatment water, 7... Sludge, 8... Dehydrator, 9... Dehydrated residue, 10... Ventilation dryer, 11... Packed bed, 12... Aeration blower, 13... Discharge Air, 14...Exhaust air, 15...Dried residue, 17
... Surplus activated sludge, 18... Mechanical dehydrator, 19... Dehydrated cake, 20... Sludge dryer, 21... Incinerator, 23
...Combustion product gas, 24,24'...Dried sludge.

Claims (1)

[Scope of Claims] 1 Mechanically dewatering the residue generated in organic sewage treatment, drying the obtained dehydrated residue using the retained heat of the discharged air of the aeration blower used in the organic sewage treatment, A method for treating water-containing materials, characterized in that the dried residue is incinerated, and the heat produced by combustion during the incineration is used for drying the sludge generated in the organic sewage treatment. 2. The method for treating water-containing material according to claim 1, wherein a part of the dried sludge is co-incinerated when the dried residue is incinerated.