JPS5817898A - Treatment of sludge before incineration - Google Patents

Abstract

PURPOSE:To pretreat the sludge drawn from a treating tank self-burnably in a short time in the stage of adding dry powder to the cake made by primary dehydration of said sludge and dehydrating the cake by pressure by specifying the rate of primary dehydration rate and the amt. of the powder to be added. CONSTITUTION:The activated sludge 1 drawn from a treating tank is dehydrated with a belt press to about 75% water content to primarily dehydrated cake 2. The cake is ground with a grinder to ground cake 3 of about <=10mm. grain size, and dried incineration ashes 4 added to the cake at <=50% by weight expressed in terms of the weight of the dry cake. When both are mixed quickly and roughly, solidified layers are formed on the surfaces of the ground cake 3, and a cake mixture 5 wherein voids are interposed among the grains of the cake 3 is produced. When such cake is placed between filter cloths and is kept pressurized, water is discharged quickly and smoothly, then the discharging decreases sharply, whereby the secondarily dehydrated cake 6 of about 40-50% water content contg. many combustible components is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pretreatment method for incinerating sludge.
In particular, it relates to a method for dewatering activated sludge extracted from a treatment tank.

Conventionally, in order to extract and dewater activated sludge, etc. that have been coagulated and precipitated by adding a flocculant from a treatment tank, a belt press, centrifugal dehydrator, vacuum filter dehydrator, etc. is used to reduce the water content to approximately 7s.
Dehydrate to a cake-like water-containing sludge of about 96 mm. In order to further convert this into self-combustible water-containing sludge with a water content of 40~SO3,
Heat drying using fuel or natural drying under the sun is performed.

However, heating and drying with the fuel requires a large amount of fuel, and the natural drying method has drawbacks such as the need to divide the sludge into small pieces, spread it over a wide area, and expose it 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 pretreating activated sludge so that it can self-combust in a short period of time while eliminating the need for fuel required for drying.

The purpose of the present invention is to apply a dry powder that absorbs moisture and coagulates to a sludge cake that has been primarily dehydrated to a moisture content of about 75 kg (powder that forms a moisture-absorbing solidified layer on the surface of the sludge cake, such as incinerated ash, silica clay, etc.). , lime, etc.) and roughly mixed to form voids inside the sludge cake via a solidified layer. The sludge cake with the voids formed is pressurized using a squeeze press.
The water 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.

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

Activated sludge extracted from the treatment tank by 1tz belt press]
A primary dehydrated cake 2 is obtained by dehydrating the cake to a moisture content of about 7 s-.

This next dehydrated cake (2 tons) is crushed by a crusher into a crushed cake 1 with a particle size of approximately 10 cm or less, and this crushed cake 5 is
30 of the weight of this pulverized cake 5 when converted into a dry cake - 9 dried inside and outside incinerated ash 4 was added quickly and roughly (incinerated ash 4 was dried between pulverized cake 50 and 11
Degree of unevenness K) When mixed, a solidified layer is formed on the surface of the pulverized cake ink, and a mixed cake S in which voids are interposed between the pulverized cakes 1 is formed through this solidified layer.

When the mixture cake 5 of kernels was placed between the filter cloth O and put into the press, and the pressure was continued to increase until 2.~/-, the water content was smoothly drained within 9 seconds, and after 9 seconds, the mixture suddenly changed. p, an-s
A secondary dehydrated cake 6 containing ag water and a high combustible content is obtained. When this secondary dehydrated cake 6 is put into an incinerator, the secondary dehydrated cake 6 which is already being burned causes fire to spread and self-combust.

As explained above, this invention can be expanded by dehydrating sludge into a dehydrated cake with a water content of about 7m, drying it, adding 9 coagulable powders, and mixing it. Even if it increases to a certain degree, it can be made into a dehydrated cake with many voids, so it has excellent drainage when pressurized.
Moreover, it is possible to obtain a mixed cake that is easily self-combustible. Therefore, there is no need for fuel for drying or incineration), and dehydration can be done easily.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of sludge pretreatment showing an embodiment of the present invention.

Claims (1)

[Claims] In a method for pre-incineration treatment of sludge extracted from a treatment tank, the extracted sludge is dehydrated to form a dehydrated cake with a water content of about 71-, and the dehydrated cake has a dry cake equivalent weight of 5.
A method for pre-incineration treatment of sludge, characterized in that dry powders of 0.096 or less are mixed to form a mixed cake containing voids, and the sludge mixed cake is further dehydrated by 7 degrees of pressure.