JPS60137500A - Treatment of organic sludge - Google Patents

Abstract

PURPOSE:To utilize the heat held by the discharged air, and to dispense with the fuel for drying the sludge by drying the organic sludge generated from aeration with the heat held by the air discharged from an aeration blower, and burning the dried sludge along with rubbish. CONSTITUTION:Since the air 9 discharged from an aeration blower 8 has a temp. of 80-90 deg.C, the air is blown into a hermetically sealable dryer 10, and passed through a layer packed with dehydrated cake 11 of organic sludge such as excess sludge 6 or the sludge from the tertiary treatment which is supplied into the dryer 10. Consequently, the dehydrated cake 11 is effectively dried, and taken out as the dried sludge 12 contg. about 30-40% water content. And the dry waste gas 13 discharged from the dryer 10 is sparged into an aerobic biological treatment stage 2 from a sparger 14 to supply oxygen.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a treatment method that can treat and dispose of sludge generated in the treatment of organic sewage and organic sludge such as sewage, human waste, and various industrial wastewater in an extremely rational and energy-saving manner. It is related to.

Hereinafter, human waste will be taken as an example and explained as a representative example of organic wastewater.

Conventionally, in human waste treatment facilities, excess activated sludge and tertiary treated sludge are concentrated using gravity silafuna, etc., and then a dewatering aid such as a cationic polymer is added.

It is dehydrated using a mechanical dehydrator such as a belt press, filter press, other compression dehydrators, or centrifugal dehydrator to form a dehydrated cake with a moisture content of around 80%, which is then incinerated.

However, because the moisture content of dehydrated cake is high, it cannot be incinerated without using a large amount of fuel, and incineration is extremely expensive (
Currently, human waste costs 1,000 to 1,200 yen per kiloliter.

For this reason, a method has recently been proposed in which the dehydrated cake is transported to a nearby garbage incinerator and incinerated together with garbage.

However, in reality, the moisture content of the dehydrated cake is high, so co-firing with waste is extremely difficult, and there is also the serious problem that the dehydrated cake becomes fluid during transportation, making it difficult to handle. Additionally, garbage incinerators are designed to incinerate garbage that has a high calorific value. Therefore, 1 calorific value is 100
Another major reason is that it is unsuitable for incinerating a dehydrated cake with a high moisture content of less than Kcal/i.

Therefore, a method has been considered in which the dehydrated cake is dried at a human waste treatment plant and then co-incinerated with garbage.
In reality, it has been found that drying is completely impractical due to the huge amount of fuel consumed, and furthermore, the exhaust gas emitted from the sludge dryer has a strong odor, so it is necessary to burn it. Deodorization is also one of the causes of significantly high fuel consumption.

Incidentally, in aerobic biological treatment of human waste, an aeration blower is used to supply oxygen-containing gas such as air to the aeration process. Conventionally, an aeration blower was simply recognized as a device whose purpose was to compress inhaled desired air and supply air (discharged air) with increased pressure to an aeration tank. There was no idea of adding additional functions. However, the inventors of the present invention have focused on the fact that the air discharged from the aeration blower has a retained heat of 80 to 90° C. due to adiabatic compression, and have arrived at the present invention, which utilizes this retained heat effectively for drying sludge.

The present invention solves the problems of the conventional drying method described above by providing multiple functions to the aeration blower used in aerobic biological treatment of organic wastewater and aerobic digestion of organic sludge. The object of the present invention is to provide a treatment method that can advantageously co-incinerate sludge with garbage.

The present invention dries the organic sludge generated from the treatment using the retained heat of the air discharged from an aeration blower used in the aeration step in the treatment of organic sewage, organic sludge, etc., and co-incinerates the dried sludge with garbage. It is characterized by this.

Furthermore, one embodiment of the present invention will be described with reference to the drawings, taking human waste treatment as an example. The removed human waste 1 flows into an aerobic biological treatment process 2 such as a biological nitrification and denitrification process, and oxygen is removed. After being supplied and subjected to aerobic biological treatment,
After the sludge is separated in the solid-liquid separation step 6, it is taken out as treated water 4 and subjected to tertiary treatment, while a part of the separated sludge is sent back and used as return sludge 5, and the surplus is returned to the system as surplus sludge 6. It is taken out and dehydrated (not shown).
be done.

The oxygen necessary for the aerobic biological treatment step 2 is supplied by the discharge air 9 of the aeration blower 8 installed in the blower installation room 7, and the discharge air 9 of the aeration blower 8 has an oxygen concentration of 80 to 90% as described above. Since the sludge has a temperature of 'C, it flows into the airtight dryer 10, and a dehydrated cake 11 of organic sludge (including sludge) such as surplus sludge 6 and tertiary treatment sludge supplied into the dryer 10 Aerate the packed bed. As a result, the dehydrated cake 11 is dried very effectively and is taken out as dried sludge 12 having a water content of about 30 to 40%. Strength? The dry exhaust gas 1 discharged from the dryer 10
6 is diffused from an aeration device 14 into the aerobic biological treatment process 2 to supply oxygen.

By the dry exhaust gas 16 diffused from the aeration device 14,
Aerobic biological treatment is performed in the aerobic biological treatment step 2, but at the same time, malodorous components in the dry exhaust gas 13 are biologically deodorized by the action of microorganisms such as activated sludge.
There is no need to provide a special deodorizing process. In addition, the dry exhaust gas 16 intermediate product also includes dust generated during drying.

This is also removed at the same time in the aerobic biological treatment step 2.

In drying in the dryer 10, for example, if αKW is the power consumption of the aeration blower 8, theoretically α(KW) x 24 (h) x 860Kca =
2064o a Kcal/.

This amount of heat can be used to dry the sludge. In other words, the aeration blower 8 is installed for the purpose of supplying oxygen to the aerobic biological treatment process 2, and since the waste heat of the aeration blower 8 is used to dry the sludge, no-cost drying is possible. It was.

Note that the moisture content of the dehydrated cake 11 is preferably 85% or less. If the moisture content of the dehydrated cake 11 is higher than 85 cm, it may be difficult to sufficiently dry the cake due to the amount of heat held by the air 9 discharged from the air blower 8. K should be 85% or less
It is preferable to carefully consider the selection of the dehydrator type and the operating conditions of the dehydrator. As an example of selecting a dewatering machine, it is advantageous to select a high-pressure dewatering machine such as a filter press or screw press that can apply high pressure to sludge.

The dried sludge 12 taken out from the dryer 10 is a dried product with a calorific value of 1800 to 2 oooKcavky, which is equivalent to that of general garbage, so it is transferred from the hopper 15 to the garbage incinerator 16. Bring in garbage 17
This makes co-firing extremely easy.

Although the above embodiments have been explained using human waste as an example, it goes without saying that the present invention can be similarly applied to sewage and sludge generated in various industrial wastewater treatments.

As described above, according to the present invention, extremely significant beneficial effects such as the first order can be obtained.

■ Eliminates the need for fuel consumption for drying sludge, resulting in significant energy savings.

■ Since the flow of discharged air from the aeration blower is used, there is no need for a fan to supply hot air to the dryer, which was required in the past.

■ Since dried sludge has the same calorific value as garbage, co-combustion with garbage is extremely easy.

■ Dry exhaust gas is automatically supplied to the aeration process and used as aeration air, and biological deodorization and dust removal are performed within the aeration process, making special deodorization and dust removal processes and equipment unnecessary.

[Brief explanation of drawings]

The drawing is a system explanatory diagram showing an embodiment of the present invention. 1... Human waste, 2... Aerobic biological treatment process, 3...
Solid-liquid separation step, 4... Treated water, 5... Returned sludge, 6
... Surplus sludge, 8. Aeration blower, 9. Discharge air, 10. Dryer, 11. Dehydrated cake, 12.
...Dry sludge, 13...Dry exhaust gas, 14...Diffuser. 16... Garbage incinerator, 17... Garbage.

Claims (1)

[Claims] 1. The organic sludge generated from the treatment is dried by the retained heat of the air discharged from the aeration blower used in the aeration step in the treatment of organic sewage, organic sludge, etc., and the dried sludge is A method for treating organic sludge that is characterized by co-combustion with garbage. 2. The method for treating organic sludge according to claim 1, wherein the moisture content of the organic sludge to be dried is kept at 85- or less.