JPS58122085A - Dehydrating method - Google Patents

Abstract

PURPOSE:To reduce dehydration time and electric power consumption, by adding an additive having high hydrating power beforehand to a material to be dehydrated, dehydrating said material by an electrosmosis method, and, if necessary, by recovering said additive by using a reverse osmosis membrane. CONSTITUTION:An electrode 2 is provided to the second half of a dehyrator 1 such as a belt press, and electric power is applied thereto from an electric power source device 2. After sludge 6 is mixed with flocculating agents 7 and additives 8 having high hydrating power, the sludge is supplied to a dehydrator 1 and is thus dehydrated. Dehydrated cake 12 is discharged to the outside of the system and separated filtrate 9 is passed through a reverse osmosis membrane 4, whereby the above-described additives 10 are recovered and reused. If the filtrate 9 is pressurized by using the membrane 4, the additives are recovered as they are, and it is only necessary to make up the additives by as much as the additives contained in the cake 12 and discharged. The consumption of the additives is decreased considerably.

Description

[Detailed description of the invention] This paper relates to improvements in dehydration methods using conventional electroosmosis methods.

In treatment facilities for clean water sludge, industrial wastewater sludge, etc., lowering the moisture content of dehydrated cakes is necessary for the purpose of energy consumption and capacity reduction in final disposal by incineration and landfill.

A conventionally used dehydration treatment method using electroosmosis is a method in which a substance to be dehydrated is electrically charged, and while io/ in the liquid moves to the cathode, the io/ moves together with water molecules, thereby dehydrating the object.

However, not only the electroosmosis method, but also dehydration machines that use mechanical pressure such as filter presses have a limit to the water content, and the electroosmosis method in particular has the drawbacks of high power consumption and long dehydration time. Considerable pressure is required to improve this.

The present invention aims to improve the drawbacks of the electroosmosis method and to propose a dehydration method that is superior in terms of performance (water content, etc.) than conventional methods. By adding electrolyte additives, such as aluminum chloride, calcium chloride, and magnesium bromide, which have a strong water use capacity when ionized and have high mobility in an electric field, we aim to shorten the dehydration time and reduce power consumption. Moreover, most of this additive is contained in the separated liquid during dehydration, so in order to reduce the consumption of this additive, it is possible to recover it using a membrane that uses reverse osmosis and reuse it. It is characterized by

Next, an embodiment of the method of the present invention will be explained based on the drawings. FIG. 1 shows the apparatus of this embodiment. In the figure, a dehydrator 1 is a conventional dehydrator such as a belt press, an electrode 2 is provided in the latter half of the dehydrator, and electricity is applied by a power supply 3. The sludge 6 is mixed in a mixing tank 5 with a flocculant 7 and an additive 8 having a strong water utilization power, supplied to a dehydrator 1, dehydrated, and discharged as a dewatered cake 12. The F liquid 9 separated in the dehydrator 1 collects the additive 10 in the permeable membrane 4 and reuses it.

In addition, in the figure, 11 is treated water, and 13 is a stirrer provided in the mixing tank 5.

In this device, the electrodes 2 are the upper and lower portions of the F cloth or the F cloth itself, and apply an electric field to the sludge after secondary dewatering. The permeable membrane 4 is pressurized to a level higher than the osmotic pressure of the additive 8 added. The water in the sludge electrified by the electrode 2 is further filtered in a shorter time due to the water utilization power of the additives in the water, so the power consumption during this time is also reduced and the water content in the dewatered cake is also reduced.

The additives contained in the F liquid 9 are normally discharged as treated water, but by pressurizing the slurry using a permeable membrane, the additives are recovered as they are and are contained in the dehydrated cake. It is only necessary to make up the substances that are emitted during the process, and the amount of additives consumed is very small.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing one embodiment of the method of the present invention. 1... Dehydrator, 2... Electrode, 3... Power supply device, 4
... Permeation membrane, 5... Mixing tank, 6... Sludge, 7...
・Flocculant, 8...Additive.

Claims (2)

[Claims] (1) A dehydration method using electroosmosis, characterized in that an additive with strong water utilization is added to the material to be dehydrated in advance. (2) In a dehydration method using electroosmosis, an additive with strong water utilization is added to the material to be dehydrated in advance, and after the dehydration treatment, the additive contained in the separated water is removed using a membrane using reverse osmosis pressure. A dehydration method characterized by recovering and reusing waste water.