JPS5990688A - Device and method for treating silica-containing water - Google Patents

Abstract

PURPOSE:To prevent settling of silica and to obtain refined water in a high yield by providing a microporous membrane or ultrafilter membrane in the fore stage of a reverse osmosis membrane, and filtering silica-contg. water with the microporous membrane or ultrafilter membrane prior to filtration of said water with the reverse osmosis membrane. CONSTITUTION:Silica-contg. water such as river water is supplied into a tank 1, and is admitted by a pump 2 into a plenum chamber 5a for admission of a filter vessel 5 where >=1mu microparticles in the water are removed by a microporous membrane (or ultrafilter membrane) 4 thereof and the filtered water contg. no microparticles is obtd. on the other side. The filtered water is supplied through a supply pipe 7 into a tank 8 below said pipe and while the water is accumulated therein to a suitable height, the water is supplied gradually under pressure into a plenum chamber 11a for admission of a filter vessel 11 contg. a reverse osmosis membrane where the water is concentrated and filtered with a reverse osmosis membrane 10 and the refined water is obtained on the chamber 11b side. The content of silica in the refined water is just about 5mg/l.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is mainly applied to raw water such as river water, city water, etc. that is relatively clean but contains silica, and is applied to silica-containing water to remove silica and make purified water. The present invention relates to processing apparatus and methods.

Conventionally, in order to remove silica components from raw water such as river water or city water, it is necessary to directly perform temporary treatment using a reverse permeation membrane, or to perform preliminary removal treatment such as coagulation sedimentation, sand E-filtration, or activated carbon treatment. There is a silica-containing water treatment method in which purified water from which silica components are removed is obtained by performing a temporary treatment with a reverse permeation membrane, but the concentration of dissolved silica in the water to be treated is high during the temporary treatment with a reverse permeation membrane. It is usually about 105/J-(F3) at room temperature.
10. ) is the maximum limit, and if concentrated beyond this point, it will begin to precipitate, clogging the reverse permeation membrane, reducing its transient performance, necessitating early replacement of the reverse permeation membrane, and causing re-permeation. For use, it is difficult to clean, and treatment with chemicals makes cleaning difficult. On the other hand, if the silica dissolved concentration does not reach the above-mentioned saturation value, the amount of purified water obtained will decrease, and on the contrary, the amount of waste water will increase, resulting in wasteful disposal, which is uneconomical. It has some drawbacks.

The present invention eliminates these drawbacks and prevents the precipitation of soluble silica from silica-containing water during p-filtration treatment using a reverse permeation membrane using a method using simple equipment, compared to the conventional method. This product provides a silica-containing water treatment device that can concentrate silica to a high concentration and obtain purified water with high yield.The silica-containing water is temporarily treated with a reverse permeation membrane to remove silica and obtain purified water. In a silica-containing water treatment device, a microporous membrane or an ultrafiltration membrane is provided before the reverse permeation membrane, and before the silica-containing water is temporarily treated with the reverse permeation membrane, the microporous membrane or the ultrafiltration membrane is It is characterized by being subjected to a temporary treatment using a membrane.

The present invention further provides an economical silica-containing water treatment method that uses the above-mentioned apparatus to concentrate silica-containing water to a high silica concentration that has not previously been possible, and yet smoothly recovers purified water with high efficiency. After passing the silica-containing water through a microporous membrane or an ultrapolar membrane, the filtered water is passed through a reverse filtration membrane until the dissolved silica concentration reaches a range of about 100 mg/I- to soo mg7t. It is characterized by performing a temporary concentration treatment.

Next, examples of the present invention will be described.

The raw material to be purified is silica-containing water, which is generally relatively clean raw water such as surface water or river water, which contains dissolved silica at a low concentration of about 10 my/1 (5ift). Raw water from places such as volcanic ash areas contains high concentrations of 507v/1 or more, and other fine particles such as insoluble silica particles, colloids of metals such as iron or their oxides, clay particles, microorganisms, etc. It generally contains particles.

Silica-containing water, for example, river water containing dissolved silica of about 6011, is directly passed through a microporous membrane or an ultra-E membrane (U).
IF membrane) to remove the contained fine particles.

As a microporous membrane, a sheet-like Ninikuriboa (N-0
40), Duracord (SW-2400W), pleated micro filter (FOO-22), Umicron (M?-40), hollow fiber SF filter (SF-301), etc. are used. Examples of UI+' membranes include sheet-shaped Diafilter (G-10T), Guiaflow (PM-10), Suhai 5 K-shaped khx-
150, G-50, tubular PS-015, HFM
-251, NTO-31120, hollow fiber-like S engineering P-3013, etc. are used. Next, the silica-containing p water that has undergone the fine particle removal treatment in this way is temporarily treated with a reverse permeation membrane.

In this case, surprisingly, the silica dissolved in p-water dissolves in a supersaturated state without forming a precipitate even if the concentration exceeds about 100 mg/J-, and the upper limit of the silica concentration is 350 to 5, although it varies depending on the equipment operating conditions, etc.
o Om; According to the device of the present invention,
Silica removal using a reverse permeation membrane for silica-containing p water is approximately 100 m9/J when silica-containing water is directly treated with a reverse permeation membrane.
- The above-mentioned disadvantages caused by silica precipitation are solved, and the silica can be removed with sufficient margin. By using the device of the present invention, the following new and advantageous treatment method has been realized, namely, the silica-containing sweat water is treated with the reverse permeation membrane until the silica concentration is about 110.
By performing a one-off process to concentrate to a supersaturation range of mg//l to 500 rro/j-, purified water can be obtained in a high yield, and the amount of concentrated water can be reduced to economically reduce silica content. Water can be treated.

Further, according to the device of the present invention, as is clear from the above, good transient performance of the reverse permeation membrane can be maintained over a long period of time, and the service life can be extended.

Next, one example of the device of the present invention will be explained with reference to the accompanying drawings.

(1) shows a tank for supplying silica-containing water a to be treated, and the tank (1) is connected to a conduit (2) with a pump (2) interposed therebetween.
3) Microporous membrane (4) or ultra-permeable membrane (4) inside
is connected to the viewing end of a filtration container (5) interposed in the middle. Thus, the inside of the filtration container (5) is partitioned by the membrane (4) into an inflow side cavity (5a) on one side and a transit side cavity (5b) on the other side.

If necessary, an outflow pipe (6) can be provided on one side of the inflow side cavity (5a). Vacant room on the temporary side (5b)
A supply pipe (forced) is provided on one side of the tank, which is opened to communicate with the upper opening of the receiving tank (8), and a supply pipe (9) led out from the bottom of the receiving tank (8) is inserted into the interior through the width of the pump. Reverse permeation membrane ← Connected to the inflow end of a p-overpressure-resistant r-permeation container αB with Q interposed in the middle.The inside of the container (11) is connected to the membrane (10).
Therefore, it is divided into a P water inflow chamber (11a) connected to the supply pipe (9) on one side and a purified water acquisition chamber (11b) on the other side. The α floor is a vacant room for sweat sellers (1
1a) A condensed water discharge conduit led out from the other side, α indicates a purified water discharge pipe led out from the empty chamber (41b). Each conduit is equipped with an on-off valve.

Next, the operation of the above device will be explained.

River water or city water to be continuously treated in the tank (1);
That is, silica-containing water is supplied and caused to flow into the soldering cavity (5a) of the ultra-permeable membrane (5) using the pump (2), and the microporous membrane (or ultra-permeable membrane) (4) Microscopic particles of 1 μm or larger are removed from the water, and sweat water that does not contain the microscopic particles is obtained on the other side. This is connected to the supply pipe (by force, the tank below it (8
). With the sweat water always stored at an appropriate height in the tank (8), the pump (L) gradually pumps it into the inflow chamber of the transit container with a built-in reverse permeability membrane ( 11
a), and performs concentration and filtration treatment using the reverse osmosis membrane QO1 to obtain purified water in the empty chamber (11b). The concentration of silica dissolved in the sweat water in the empty chamber (11a) is adjusted to
For example, the temporary treatment can be carried out by making the concentrated water 300 my7Q.

Thus, the vacancy (1l b
), purified water containing only 5 μ/L of silica was continuously obtained. After the continuous production of purified water was completed, the reverse permeation membrane α was examined, but no silica precipitation was observed.

Next, an experimental example of the present invention will be explained.

Example: Water glass was added to city water to achieve a dissolved silica concentration of 9'4t.
/1, silica-containing water was prepared with a pH of 6.5, passed through a microporous membrane Nuclebore N-040, and the resulting F solution was passed through a reverse osmosis membrane (RO membrane) diaphragm. Purified water was obtained by filtration with filter RM-97. The silica concentration and clogging index (F1 value) in each treatment step were measured. The results are shown in the table below.

Liquid volume Silica concentration F1 value silica-containing water (raw water) 200+++195m12
4.3 Microporous membrane water 200//94 t
t O, IRQ membrane water (purified water) 150//
5 tt O, IRO membrane concentrated water (drainage) 50// 275tt O, 1
When the RO membrane was examined after production, no silica precipitation was observed.

Example Without using the microporous membrane, the same silica-containing water as in Experimental Example 1 was directly subjected to a temporary treatment using the same RO membrane as above at a silica concentration of 132 m9/1. Silica precipitates were observed in the RO membrane after use. Next, the measurement results in each treatment step will be shown.

Liquid amount Silica concentration F1 value silica-containing water (raw water) 200mA! 95m
fJ, 4.3RO membrane p water (purified water) 150
77 4 tt, 0.1RO membrane concentrated water (
Drainage) 501/132/l 5.
6 Experimental stripping 2 UII' membrane diafilter G-10 instead of microporous membrane
The experiment was carried out in the same manner as in Experimental Example 1 except that T was used. As in Experimental Example 1, no silica precipitation was observed on the RO membrane. The measurement results in each treatment step were as follows.

Liquid amount Silica concentration FI value Silica-containing water (raw water) 101000TL195/
L 4.3UIP membrane water 500p
92tt O, IRQMP water (refined water)
3751F 5 tt O,IP,0I
il (concentrated water (drainage) 125//275t
t O, 2 Examples Well water (silica concentration 56 m9/1) was poured into a microporous membrane 5F-
After filtering with 301, the P solution was passed through RO membrane HoloSep HR5.
230, and continuous processing was performed.

The results are shown in the table below.

Liquid volume Silica concentration F1 value silica-containing water (well water) 8.7) -7 minutes 56ψ
3.5 Microporous membrane p water tt tt
O, IRO membrane p liquid tt 6.5p
4tt O, 0υt Water (concentrated liquid)
5.2//205//0.1 No silica precipitate was observed in the RO membrane after use.

Example: The same well water as in Experimental Example 6 was directly passed through the same Bo membrane for continuous treatment, but the transient performance of the RO membrane decreased by 20% after one week, and silica microcrystals were present in the concentrated solution. has become recognized.

The silica-containing water to be treated that is applied to the present invention can be treated by directly over-treating relatively clean river water, city water, well water, lake water, etc. using a microporous membrane or UF membrane, and then using an RO membrane. Generally speaking, it is advantageous, but if it contains a relatively large amount of impurities, it should be pre-treated with a combination of one or more of coagulation sedimentation, sand filtration, activated carbon, ion exchange resin, etc. to appropriately purify the silica-containing material. It can also be applied to water.

In this way, according to the present invention, since silica-containing water is treated with a backward permeation membrane that has been filtered with a microporous membrane or an ultrafiltration membrane, it is significantly more effective than directly treating it with a reverse permeation membrane. Even when concentrated to a high silica concentration, silica does not precipitate, and purified water can be produced smoothly and continuously in a high yield.

[Brief explanation of the drawing]

The drawing is a diagram showing an example of the device of the present invention. (1)...Raw water supply tank (4)...Microporous membrane or ultrap-permeable membrane α0)...Reverse permeability membrane

Claims (1)

[Claims] 1. In a silica-containing water treatment device for removing silica and obtaining purified water by temporarily treating silica-containing water with a reverse permeation membrane, a microporous membrane or an ultrafiltration filter is provided before the reverse permeation membrane. 1. A silica-containing water treatment device, characterized in that a membrane is provided, and the silica-containing water is subjected to one-time treatment through the microporous membrane or the ultrapolar membrane before the silica-containing water is subjected to one-time treatment through the reverse permeation membrane. 2 After passing the silica-containing water through a microporous membrane or an ultrafiltration membrane, the temporary water has a dissolved concentration of silica of about 100 mg/
A method for treating silica-containing water, which comprises carrying out a temporary treatment of concentrating with a reverse permeation membrane until the concentration reaches a range of I- to 500 my/J.