JPS58180212A - Dehydrating method - Google Patents

Abstract

PURPOSE:To reduce a time lag and to perform a detecting operation easily, by detecting the thickness of flocculated flock in a gravity-filtration process. CONSTITUTION:A sludge to be treated is well mixed and agitated in a mixing tank 4 with a proper quantity of high-molecular flocculant corresponding to the concentration of the sludge at the time of operation, and the mixture is sent, after a flucculation treatment, to a gravity-filtration process 5 with the aid of a belt press, a wedge-pressing process 6, and a press-squeezing process 7 in sequence, and is finally discharged out of the system as a treated sludge. When the thickness of the flucculated floc is changed by the fluctuation of the concentration of a sludge to be treated, the changing quantity is detected by a thickness detector 1 of a flocculated floc and is sent to a controller 2, and the flow rate of a high molecular flocculant is adjusted by a flow rate controller 3 to feed a proper quantity of the flocculant to the mixing tank 4. Thus, when a sludge to be treated of a constant flow rate is treated, the dehydration treatment is performed in low cost and in excellent dehydrationrate without using any expensive sludgeconcentration meter.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a dehydration method using a filtration pressurized dehydration method.

In sludge dehydration methods that use filtration and pressure methods such as belt press dehydrators, a certain amount of polymer flocculant is added to the sludge to be treated, the sludge is made into flocs, the separated water is filtered by gravity, and after natural dehydration, it is gradually added Press and dehydrate. The amount of polymer flocculant for the sludge to be treated is determined in advance depending on the concentration of the sludge to be treated, but the sludge to be treated does not always have the concentration set at the initial stage.
．． ′ is difficult to maintain. Depending on the level of maintenance and management, fishing costs fluctuate by about 75 cm.In this case, there is a fee to take the safe side and add an appropriate amount of polymer flocculant to 2 or more, which is extremely expensive in terms of la/2/g cost. It was a disadvantage.

In order to solve the above problems, the present invention proposes a method that can always add an appropriate amount of flocculant in response to changes in the concentration of the sludge to be treated. In a dehydration method in which the obtained coagulated Fronoku'kP cloth is sandwiched and dehydrated through a gravity filtration step and a pressure filtration step.
The supply t of the coagulated flocs to the P cloth is kept constant, and the variation in the concentration of the coagulated flocs is determined by detecting the thickness of the coagulated flocs in the above-mentioned gravity γ process.

Provided is a dehydration method characterized in that an appropriate amount of flocculant corresponding to the flocculation concentration is added in advance.

In the method of the present invention, we focus on the fact that the thickness of the flocs that progresses in the gravity filtration step and the sludge concentration are proportional,
Adjust the addition of flocculant by detecting the floc thickness,
An appropriate amount of flocculant is always added in response to changes in concentration in order to reduce porosity and waste costs.

According to the method of the present invention, by detecting the thickness of coagulated flocs during the gravity filtration process, there is less time lag, and detection during the gravity filtration process is easy.

All you have to do is use a conventionally used level detector, etc.
It has the advantage that detection work is easy.

Next, an embodiment in which the method of the present invention is applied to sludge dewatering treatment using a belt press will be described with reference to the drawings.

In FIG. 1, the sludge to be treated is thoroughly mixed and stirred in a mixing tank 4 with an appropriate amount of polymer flocculant corresponding to the sludge concentration during operation, and after the flocculation treatment, a gravity filtration step 5 using a belt press is performed. The sludge is sequentially sent to a pressurization process 6 and a pressurization filtration process 7, and becomes treated sludge and is discharged from the system. When the concentration of the sludge to be treated changes and the coagulated floc thickness changes, the coagulated floc thickness detector 1 sends the amount of change to the controller 2Vc, and the flow rate regulator 3 adjusts the flow rate of the polymer flocculant to mix the appropriate amount. Supply to tank 4.

This eliminates the need to use a sludge concentration meter, which is 70% more expensive, when treating sludge in a certain equipment.

It is possible to perform dehydration treatment at low cost and with high dehydration efficiency.

Table 1 shows experimental data when sewage sludge was used as the material to be treated, and the amount of sludge supplied to the belt press, the speed of each cloth, and the tension of the P cloth were constant.

As can be seen from Table 1, No. 1 fi, the thickness of the flocculated flocs in a culm with 1 gravity overflow is greater than the thickness of the dewatered cake, so fluctuations in sludge concentration can be easily seen and accurate detected values can be obtained.

Fig. 2 shows a horizontal sludge type dehydrator, and Fig. 1 shows that the fed flocculated sludge is fed onto a P cloth 12 and dehydrated by gravity, while being gradually pressurized and dehydrated in a pressurizing device 13, and then passed through a cake peeling scraper. 14 and discharged out of the system.

The pressurizing device 13 has a mechanism that can adjust the clearance between it and the door cloth 2 using a belt-like thick rubber plate 15. In addition, 16 is a cloth support roller, and 17 is a thick rubber support roller.

18 is a door liquid receiver, 19 is a P cloth washing machine, l is a gravity filtration process, and ■ is a pressure filtration process.

This type of dehydrator is used as a pre-dehydrator or as a standalone unit for dewatering sludge that is weak due to the coagulation flow.

The method of the present invention is suitable for application to this apparatus and others in addition to belt presses.

[Brief explanation of the drawing]

, ig1 are process diagrams showing one embodiment of the method of the present invention. FIG. 2 is an explanatory diagram showing horizontal/tsukuna type dewatering. ■... Gravity p-pass process, ■... Pressure p-pass process, 11
...Mud supply, 12...P cloth, 13..."Pressure device, 14
...Cake peeling scraper, 15...Thick rubber band, 16.17...Support roller, 18...F cloth holder, 19...Door cloth cleaning. Procedural amendment (voluntary) September 17, 1980 Case display Showa 5'74I: Patent shaft cylinder 653
Relationship with the case of the person amending the name of the invention No. 90 Dehydration method Patent applicant address 5, Marunouchi Ny-chome, 1u-ku, f-dai, Tokyo
Qiao No. 1 Name (6Xl) Mitsubishi Heavy Industries Co., Ltd. Agent Contents of 4m (1) The gap 1 with the 1F fabric 2 on page 5 lines 10-11 of the specification is changed to ``the gap with the P fabric 12''. ” he corrected. (2)

Claims (1)

[Claims] In a dehydration method in which the flocs obtained by adding a flocculant to the material to be treated and flocculating are sandwiched between F cloths and dehydrated through a gravity filtration process and a pressure filtration process, the amount of flocs supplied to the P cloth is is determined by detecting the thickness of the flocs at the gravity filtration step, and an appropriate amount of flocculant corresponding to the flocculation concentration is added in advance. Dehydration method.