JPS5898200A - Dehydration of sludge - Google Patents

Abstract

PURPOSE:To remarkably enhance the dehydrating power of a dehydrator, in dehydrating excess sludge formed in the purification of filthy water, by adding an inorganic salt to the sludge, reserving the sludge for a specified period, and then dehydrating the sludge. CONSTITUTION:Slurry 1 of biocells or SS contg. biocells, e.g. active sludge or sludge formed in the treatment of night soil, is let flow into a mixing cell 2. At this time, an inexpensive innoxious inorganic salt such as NaCl or its solution 3 is concurrently added to the slurry, and the slurry is agitated by an agitator 4 and reserved as such for a specified period. During the reserving period, water in cells is permeated through biomembranes and exude outside the cells by osmotic pressure. The slurry rendered into said state is fed to a dehydrator 6 by a pump 5 and dehydrated. An effluent 7 is desalinated by a reverse osmosis device 8. Desalinated water 9 is drained as purified water, while water 10 having high concentration of the salt is returned to the mixing cell 2 and reused. The water-retaining ratio of dehydrated cake discharged from the dehydrator 6 is remarkably lowered so that the costs of incineration, disposal, etc. in the next step can be lowered.

Description

[Detailed description of the invention] The present invention relates to improvements in sludge dewatering methods.

Excess sludge from the sewage treatment plant and human waste treatment plant is currently 73
- After dewatering using centrifuges, peridots, filter presses, etc., the waste is incinerated and then dumped in the ocean, but as mechanical improvements have been made to dehydrators, their performance has reached a plateau.

Conventional dehydrators were generally intended to separate the 88 minutes in the slurry from the liquid that clouded the SS (liquid outside the SS).

Therefore, the present invention dramatically increases the dehydration performance of the dehydrator by Vc1i% by simultaneously removing the moisture inside the membrane (biological moisture) in the case of SS or living organisms, and further incinerates it. This method was proposed for the purpose of lowering the cost of sludge, and as a pretreatment, inorganic salts are mixed with the sludge and allowed to stagnate for a certain period of time to remove the living cells contained in the sludge. A sludge dewatering method is characterized by temporarily dehydrating the water inside R411Its by leaching it out to the outside by osmotic pressure, and when dewatering sludge, as a pretreatment, inorganic salts are mixed with the sludge and left for a certain period of time. Living body fl contained in whistle dQ
After the water in the cells is leached out of the cell by osmotic pressure, it is dehydrated, and the dehydrated water is separated into concentrated salt water and fresh water using a desalting device, of which the concentrated salt water is used for pretreatment. We provide a dehydration method that is characterized by:

In the method of the present invention, as a pretreatment for the dehydration process, sludge is mixed with salt-free salt, and water contained in the sludge is leached out of the cells by the coagulant pressure action of the living cells. In the dehydration process, not only extracellular water but also intracellular water can be removed at the same time.

Furthermore, the dehydrated water generated in the dehydration process is separated into concentrated salt water and fresh water using a desalination device, and in order to reuse the concentrated salt water for pretreatment, the violet equivalent to a small amount of unsalted seaweed that accompanies the dehydrated goo is removed. Continuous dehydration processing can be carried out smoothly simply by replenishing the water.

Since no inorganic salts or jJF are released outside the system, there are no problems such as environmental pollution.

Next, one embodiment of the method of the present invention will be explained based on the drawings.

In Figure 1, living organisms such as activated sludge, human waste sludge, etc.
A slurry 1 containing O8s containing cells or biological cells is made to flow into the ellipse 2. At this point, a harmless non-toxic salt such as NaC11 is added to the mixing tank 2 at the same time, stirred by the stirring device 4, and stirred for a certain period of time. 'ru. During this time, the water inside the cut 11# passes through the biological membrane due to osmotic pressure and leaks out of the cut 11@. The slurry in such a state is transferred to the dehydrator 6 by the bokubu 5 and is dehydrated.

Note that the desorbed water 7 is generated by reverse osmosis (reverse osmosis).
ia) The water 9 from which salt is removed by desalination in the device 8 is discharged to the outside of the yarn as treated water or reused.

In addition, the water with a salinity of 11G (100 g) is returned to the mixing tank 2 and used to mix up the water content.

There are two types: front model, Svaira IL winding model, hollow fiber model, etc.
It is sufficient to use one of these types.

When such a system is operated, the operation can be continued smoothly by adding from the salt supply line 6 a spoon equivalent to the slight salt accompanying the dehydrated goo 11.

Note that the inorganic salts used in the present invention are common; tlfi
Compound salts are suitable, inexpensive, easy to handle, and easy to unravel for 1 m.
It is even more desirable if it is harmless.

Next, the results of a trial conducted to confirm the action and effect of the method of the present invention will be described.

A slurry (excess sludge generated at a sewage treatment plant) containing biological fill I is poured into a stirring tank 21 as shown in Fig. 2,
A certain amount of NtrCl was added to this, and after stirring for a certain period of time using the stirring P1 machine 22, this slurry was dehydrated using a helido press type dehydrator. When the above temporarily treated product was directly dehydrated using a belt press-type jusuiiso without adding NaCe, the water content of the dehydrated product was 79% by weight, and the dehydration effect obtained by the method of the present invention was significantly superior in VC. It has been found.

According to the above 5 VC, non-inventor, activated sludge,
When dehydrating sludge treated with human waste, other sludge containing sludge, or SS slurry containing live 9IJ cells, a marked dehydration effect can be obtained compared to the conventional dehydration method, and the dehydration rate can be reduced by %I. It has the great advantage of being 'l'J and does not cause pollution problems.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the method of the present invention. FIG. 2 is an explanatory diagram showing the test device. i-ss slurry, 2. Mixing tank, 6. Added salt, 4. Stirring device, 6. Dehydrator, 7. Desorbed water. 8 reverse osmosis equipment, 9 fresh water, 10 salt water. 11 Dehydration goo ten.・ :1. , 2 (Rikiha I Sekiroku 2)

Claims (2)

[Claims] (1) When dehydrating sludge, as a pretreatment, inorganic salts are mixed with the sludge and left to linger for a certain period of time to leach out the water inside living cells contained in the sludge to the outside of the cells by osmotic pressure. , a sludge dewatering method characterized by dewatering. (2) When dehydrating sludge, as a pretreatment, inorganic salts are mixed with the sludge and the sludge is allowed to float for a certain period of time. After being leached out of the cells by osmotic pressure, it is treated with fresh water, and the desorbed water is separated into thick salt water and fresh water using a desalination device, of which 17 brine is reused for pretreatment. Features of sludge dewatering method.