JPH06190399A - Method and equipment for treating dehydrated sludge - Google Patents

Abstract

PURPOSE:To inexpensively treat dehydrated sludge by incinerating dried sludge obtained by the fermentation treatment of dehydrated sludge in the presence of aerobic fermentation bacteria as it is or in a state mixed with dehydrated sludge. CONSTITUTION:A part of the dehydrated sludge S generated in a sewage treatment plant is stored in a dehydrated sludge hopper 10A and the remainder thereof is charged in a tank 2 from the supply port 5 of a fermentation device 1. The dehydrated sludge S is indirectly heated by circulating water in the presence of aerobic fermentation bacteria within the tank 2 and fermented while stirred by a stirrer 4 to become dye sludge Sa. The dry sludge Sa is charged in a dry sludge hopper 10B and calcium carbonate is charged in the hopper10B. The dehydrated sludge and/or dry sludge in both hoppers 10A, 10B are charged into an incinerator 15 to be incinerated. By this constitution, dehydrated sludge can be treated at a low temp. while an offensive smell level is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating dehydrated sludge and a treatment facility therefor.

[0002]

BACKGROUND OF THE INVENTION Conventionally, as a method for treating sewage sludge, the sludge generated at a sewage treatment plant is temporarily dehydrated, and at least a part of this dehydrated sludge is
There is a method in which an indirect heating dryer using steam or heat transfer oil, a rotary dryer that directly dries hot air, or the like is used to dry the sludge, or the dried sludge and the dehydrated sludge are incinerated in an incinerator.

By the way, in this method, the dehydrated sludge itself is heated to 90 to 100 ° C., locally up to about 200 ° C. in a dryer, so that the concentration of odor generated is high, and therefore the combustion method is used. A deodorizing device having a complicated device configuration such as a chemical cleaning method was required. Further, since the generated gas generated by the dryer has a high temperature, not only the thermal efficiency is poor, but the exhaust gas contains various combustible components, so that the risk of explosion and combustion of the generated gas is high, There were various problems such as the handling required skill. Further, the dryer is generally expensive, and in a small-to-medium-sized sewage treatment plant in which the amount of dehydrated sludge generated in one day is as small as several tons to tens of tons, intermittent operation is often performed, resulting in high usage efficiency. bad. Therefore, in particular, the advent of a simple and inexpensive dryer has been desired.

Therefore, as a result of various studies on the dryer, the present inventor fermented the dehydrated sludge in the presence of aerobic fermentation microorganisms, but it took 24 to 48 hours, but the water content of the dehydrated sludge was 10 to 10. It has been found that the dried sludge can be reduced to 30% by weight, the fermentation temperature is relatively low, and the odor concentration is low, so that it can be deodorized by a simple deodorizer such as an activated carbon adsorption tower. Therefore, an object of the present invention is to provide a method for treating dehydrated sludge using an inexpensive fermenter that ferments with dehydrated sludge in the presence of an aerobic fermenting microorganism as a dryer, and a treatment facility therefor.

[0005]

In order to achieve the above object, in the invention of claim 1, the dehydrated sludge is subjected to a fermentation treatment in the presence of an aerobic fermenting microorganism to produce a dried sludge, and the dried sludge is used alone. Alternatively, it is mixed with dehydrated sludge and incinerated in an incinerator. In the invention of claim 2, slaked lime or calcium carbonate is charged into the incinerator together with the sludge. Further, in the invention of claim 3, a fermenter for dehydrated sludge using aerobic fermenting microorganisms, a hopper for storing the dried sludge from the fermenter, and a fluidized bed incineration for incinerating the dried sludge cut out from the hopper. A furnace and an air preheater that recovers heat from the exhaust gas from this incinerator,
The deodorizer provided in the exhaust system of the fermenter and the ceramic filter type dust collector provided in the exhaust system of the incinerator.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of the dehydrated sludge treatment equipment of the present invention, which is roughly composed of a fermenter 1, a deodorizer 7, and a dehydrated sludge hopper 1.
0A, a dried sludge hopper 10B, a fluidized bed incinerator 15, an air preheater 18, and a dust collector 22. The fermentor 1 has a two-tank structure, and a fermenter 1 has an outer circumference provided with a hot water zone 3 for passing hot water heated by a water heater 9 to heat the tank 2 from the outside. In addition, an agitator 4 that is rotationally driven by a motor (not shown) is provided in the tank 2. In addition, 5 is a supply port of the dehydrated sludge S into the tank 2, 6
Is an outlet of the dried sludge Sa, 7 is a deodorizer for deodorizing the fermentation gas generated in the tank 2, and 8 is an exhaust fan for deodorization. Further, the fermentor 1 may have a single tank structure, in which case two units are arranged in parallel. Further, the device for heating the fermenter 1 may be a heater or the like.

The dewatered sludge hopper 10A stores dewatered sludge S, and the dewatered sludge S in the hopper 10A is supplied into the fluidized bed incinerator 15 described below by the cutting means 11a. On the other hand, the dried sludge hopper 10B stores dried sludge Sa dried in the fermenter 1 and calcium carbonate (CaCO ₃ ) input from the outside, and the dried sludge Sa and calcium carbonate in the hopper 10B are cut out. It is supplied to the fluidized bed type incinerator 15 while being stirred by the means 11b. The dried sludge Sa in the hopper 10B can be discharged to the outside without being supplied to the fluidized bed incinerator 15.

The fluidized bed incinerator 15 has a furnace bottom 16 inclined in one direction, has a bottom discharge port 16a at the lowest portion thereof, and has the following high temperature air in the vicinity of the furnace bottom 16. Is equipped with a jetting pipe 17 having a large number of injection holes for jetting the silica sand (fluid medium) filled in the furnace and making the filling height of the silica sand shallow, The burden is lightened. Further, an air preheater 18 is provided on the upper side wall of the incinerator 15, and the blower 2 for flow is provided.
The air from No. 1 is preheated by the air preheater 18, and its hot air is ejected from the ejection pipe 17, while the water heater 9
Is supplied to the hot water zone 3 to heat the circulating water. Further, a burner 19 is provided on the furnace wall on which the upper part of the fluidized bed formed by the air jetted from the jet pipe 17 is located.
Dewatered sludge S cut out from each of the hoppers 10A and 10B
And / or an in-furnace charging device 20 for the dried sludge Sa is provided.

The dust collector 22 is of a well-known ceramic filter type using a porous ceramic pipe, and removes the incineration ash discharged together with the exhaust gas from the top exhaust port 16b of the incinerator 15, and is removed. The exhaust gas after being trapped is sucked by the exhaust gas exhaust fan 23 and released to the atmosphere. On the other hand, the collected incineration ash or the like is discharged by the indirect cooling ash discharger 24. Reference numeral 25 denotes an outside air suction valve, and the exhaust gas from the exhaust port 16b is at a high temperature, and the dust collector 22 has to have a high-grade adiabatic fireproof structure, but the outside air is sucked and mixed to bring the exhaust gas temperature to 300 to 350 ° C. By lowering it, a relatively inexpensive and simple structure is possible.

Next, the operation of the dewatered sludge treatment facility of the above construction will be described. First, a part of the dehydrated sludge S generated in a sewage treatment plant or the like is stored in the dehydrated sludge hopper 10A, and the rest is put into the tank 2 through the supply port 5 of the fermenter 1 in the presence of aerobic fermentation microorganisms. In addition, it is indirectly heated by the circulating water described below, stirred by an agitator 4 at an appropriate temperature and fermented at about 60 ° C. for 24 to 48 hours, and the dehydrated sludge has a water content of 10 to 30% by weight. It becomes dry sludge. Since the fermentation gas having an odor generated during the fermentation is extremely low temperature as compared with the conventional one as described above, it is deodorized by the simple deodorizer 7 such as an activated carbon adsorption tower and released to the atmosphere. .

The dried sludge Sa which has been subjected to the fermentation treatment as described above is put into the dried sludge hopper 10B. Also,
Calcium carbonate is put into this hopper 10B. Then, the dehydrated sludge and / or the dried sludge in both the hoppers 10A and 10B are put into the incinerator 15 by the in-core throwing machine 20 and incinerated, but at the start of the operation of the furnace,
While heating the inside of the furnace to about 800 ° C. by the burner 19, the flowing air from the ejection pipe 17 is preheated to about 500 ° C. via the air preheater 18, and the silica sand is caused to flow by this flowing air. The above-mentioned dehydrated sludge and / or dried sludge to be charged is burned. In this case, the amount of dry sludge to be fed is adjusted so that the sludge itself burns, and when it becomes a self-burning state, the burner 19 is extinguished. The calcium carbonate may be supplied to the furnace charging device 20.

When burning the sludge, sulfur and chlorine in the sludge react with calcium carbonate added together with the sludge at a high temperature to form calcium sulfate or calcium chloride, which is absorbed and removed to remove SOx and HC.
Generation of 1 is suppressed. Note that slaked lime may be used instead of the calcium carbonate.

On the other hand, the exhaust gas at about 800 ° C. is the air preheater 1
After passing 8 to 350-450 ° C, top exhaust port 1
Discharged from 6b, mixed with cooling air on the way, 300-35
The temperature reaches 0 ° C., reaches the dust collector 22, and the incineration ash and the like contained in the exhaust gas is collected here and is stored in the ash storage bag or the like by the indirect cooling type ash discharger 24 and appropriately disposed, while the exhaust gas is exhaust fan. 23 is released to the atmosphere. Further, part of the high temperature air heated by the air preheater 18 reaches the water heater 9 and heats the circulating water in the hot water zone 3. However,
When the furnace is stopped, each tank 2 of the fermenter 1 is heated by a heater or the like (not shown). further,
As described above, 24 times is required to dry the dehydrated sludge in the fermenter 1.
Since it takes ~ 48 hours, the dehydrated sludge and the dried sludge are alternately charged into each tank 2. Since the dried sludge Sa is a kind of compost, it may be taken out from the dried sludge hopper 10B as compost.

[0014]

As is apparent from the above description, according to the method for treating dehydrated sludge of the present invention, the dehydrated sludge is dried at a low temperature because it is fermented in the presence of an aerobic fermenting microorganism. Therefore, the odor level is low, and there is no danger of explosive combustion, and an inexpensive treatment method can be obtained. In addition, if calcium carbonate or slaked lime is put into the incinerator together with the sludge, SOx will be generated in the incinerator.
And HCl can be absorbed and removed, and the conventional wet cleaning of exhaust gas with water or an alkaline solution is not required, and a special exhaust gas treatment device is not required. Further, in the processing equipment, since a fermenter is used as a dryer, the odor level is low, and a simple equipment such as an activated carbon adsorption tower can be applied as a deodorizer. Further, since the porous ceramic filter type dust collector is used as the dust collector, there is an effect that high-efficiency dust removal can be performed at high temperature.

[Brief description of drawings]

FIG. 1 is a diagram showing a dewatered sludge treatment facility of the present invention.

[Explanation of symbols]

1 ... Fermenter, 2 ... Tank, 4 ... Stirrer, 7 ... Deodorizer, 9 ... Water heater, 10A ... Dewatered sludge hopper, 10B ... Dry sludge hopper, 11a, 11b ... Cutting means, 15 ... Fluidized bed type incinerator , 17 ... Jet pipe, 18 ... Air preheater, 19 ... Burner,
22 ... Dust collector, S ... Dewatered sludge, Sa ... Dry sludge.

Claims (3)

[Claims] 1. A dehydrated sludge characterized in that the dehydrated sludge is subjected to fermentation treatment in the presence of an aerobic fermenting microorganism to produce a sludge in a dry state, and the dried sludge is burned alone or in combination with the dehydrated sludge in an incinerator. Processing method. 2. The method for treating dehydrated sludge according to claim 1, wherein slaked lime or calcium carbonate is charged into the incinerator together with the sludge. 3. A fermenter for dehydrated sludge using an aerobic fermenting microorganism, a hopper for storing the dried sludge from the fermenter, a fluidized bed incinerator for incinerating the dried sludge cut out from the hopper, and An air preheater for recovering heat from the exhaust gas from the incinerator, a deodorizer provided in the exhaust system of the fermenter, and a ceramic filter dust collector provided in the exhaust system of the incinerator, characterized in that Dewatered sludge treatment equipment.