JPS5817896A - Dehydrating method for sludge - Google Patents

Abstract

PURPOSE:To obtain dehydrated cake which is self-burnable quickly in the stage of dehydrating the sludge drawn from a treating tank by pressure by forming the cake mixture wherein dry powder is interposed in the sludge. CONSTITUTION:The activated sludge 1 drawn from a treating tank is dehydrated with a belt press to from primarily dehydrated cake 2. Said cake is ground with a grinder to ground cake 3 of approximately <=10mm. grain sizes. Dried incineration ashes 4 are added to said cakes and both are mixed quickly and roughly (to the extent that the ashes 4 exist irregularly among the grains of the cake 3 in the dry state). Then solidified layers are formed on the surfaces of the cake 3, and the cake mixture 5 wherein voids interpose among the grains of the cake 3 is produced. If the cake is placed between filter cloths and is kept pressurized with a compression press, water is discharged smoothly in a short time then the discharging decreases sharply whereby the secondarily dehydrated cake 6 of about 40-50% water contg. many combustible components is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dewatering activated sludge extracted from a treatment tank.

Conventionally, in order to extract and dehydrate activated sludge, etc., which is coagulated and precipitated by adding a flocculant from a treatment tank, a belt press, centrifugal dehydrator, vacuum filter dehydrator, etc. is used, and the water content is approximately 75%.
Dehydrated to a cake-like water-containing sludge. To further convert this into self-combustible water content 411~SO@O water sludge,
Heat drying using fuel or natural drying under the sun is performed.

However, heating drying using fuel requires a large amount of fuel, and for natural drying, the sludge must be divided into pieces, spread over a wide area, and exposed to the sun for a long time.

In view of the above drawbacks, it is an object of the present invention to provide a method for dewatering activated sludge in a short period of time in a self-combustible manner that eliminates the need for fuel required for drying.

The purpose of this invention is to apply dry powder* (powder that absorbs moisture and forms a solidified layer on the surface of the sludge cake, such as incinerated ash, silica, etc.) to a sludge cake that has been primarily dehydrated to a water content of about 78%. (dry soil, lime, etc.) and mix roughly.
All voids are formed inside the sludge cake through an assimilation layer. By forming these voids and compressing the sludge cake with a pressure press, the moisture contained in the sludge cake is discharged and dehydrated through the gaps in the assimilation layer to obtain a self-combustible secondary dehydrated cake with a high combustible content. It is.

An embodiment of this invention will be explained with reference to FIG.

Activated sludge 1 extracted from a treatment tank is dehydrated using a belt press to a water content of about 75% to obtain a primary dehydrated cake 2.

This dehydrated cake 2 is pulverized by a pulverizer into a pulverized cake S with a particle size of 1 ounce or less, and this pulverized cake 2 is converted into a dry cake with a weight of 9. When 4 tons of dried incinerated ash is added quickly and roughly (directly on the ash that is unevenly interposed between the crushed cake ink), a solidified layer is formed on the surface of the crushed cake ink. A mixed cake mass is formed in which voids are present between the pulverized cakes 10 via this solidified layer. This mixed cake S is sandwiched between filter cloths and put into a compression press, p, 2a.
If the pressure continues to rise to K1/-, the water content will be drained smoothly within 30 seconds or so, then the drainage will suddenly change and decrease, and even if the pressure is increased thereafter, the amount of drainage will be small, and the water content will be 40 to 5o9.
6. Secondary dehydrated cake containing a lot of water and combustible content 6. As explained above, in this invention, by squeezing the sludge cake after interposing the voids of dry powder between the sludge cakes, the water pushed out from the sludge cake passes through the spaces of the dry powder. Since the sludge cake is discharged with water, the moisture in the sludge cake can be quickly dehydrated to the extent that the sludge can self-combust. Therefore, fuel for drying and incineration is not required, and it can be processed quickly after dehydration.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a sludge dewatering process showing an embodiment of the present invention. 1: Activated sludge, 4! Dry powder, 5: mixed cake, 6: secondary dehydrated cake

Claims (1)

[Claims] In a method of dewatering sludge extracted from a treatment tank so that it can be incinerated, a dry powder is interposed between the extracted sludge to form a mixed cake, and this mixed sludge is pressurized (using a press) to form a dehydrated cake that can be self-combustible. A sludge dewatering method characterized by: