Batch type concentrator

Abstract

To provide a batch type concentrator capable of preventing clogging of a back pressure control valve for applying back pressure provided in a concentrated water line.SOLUTION: After a predetermined amount of raw water is stored in a raw water tank 2, valves 4 and 6 are opened and a pump 5 is operated. Water in the raw water tank 2 is passed sequentially through first to fourth RO devices 11 to 14 via pipes 3 and 7, and concentrated water from the fourth RO device 14 is returned to the raw water tank 2 via a pipe 15, an orifice 16, a back pressure control valve 17, and a pipe 18. Permeated water is taken out via a permeated water pipe 20 and a permeated water tank 21. Since the orifice 16 is provided, a sufficient back pressure can be applied to each of the RO devices 11 to 14 including the RO device 14 without excessively reducing a valve lift of the back pressure control valve 17. Therefore, clogging of the back pressure control valve 17 can be prevented.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a batch-type concentration device using a reverse osmosis membrane device (RO device). [Background technology]

[0002] Patent Document 1 describes a filtration treatment device as a batch-type concentration device that concentrates the water to be treated in a batch-type manner, in which multiple reverse osmosis membrane modules are connected in series, contaminated water in a contaminated water tank is passed through the reverse osmosis membrane modules in sequence, concentrated water from the final reverse osmosis membrane module is returned to the contaminated water tank, and permeated water from the reverse osmosis membrane module of each stage is extracted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-126767 A Summary of the Invention [Problem to be solved by the invention]

[0004] When water is passed through membrane modules arranged in series at a high linear flow rate, the module differential pressure increases, and the effective pressure of the downstream module decreases. That is, the water pressure of the water to be treated is higher in the upstream reverse osmosis module and lower in the downstream reverse osmosis membrane module. As a result, the membrane surface of the downstream reverse osmosis membrane module is more likely to become clogged with dirt, and the removal rate decreases due to the drop in effective pressure. In particular, when wastewater is concentrated batchwise, the osmotic pressure of the wastewater increases with concentration, so that the effective pressure on the membrane at the time of reaching the concentration level is smaller than that at the beginning of operation, and the removal rate further decreases due to the drop in effective pressure. Therefore, the quality of the permeate water deteriorates with concentration.

[0005] Furthermore, when circulating wastewater containing high concentrations of SS (suspended solids), it is desirable to have a structure that prevents SS from remaining in the piping and valves (for example, back pressure control valves).

[0006] An object of the present invention is to provide a batch type concentration apparatus capable of preventing clogging of a back pressure control valve for applying back pressure provided in a concentrated water line. [Means for solving the problem]

[0007] The present invention relates to the following.

[0008] [1] A batch type concentration apparatus having a raw water tank, a reverse osmosis membrane device through which water in the raw water tank is passed, a concentrated water line that returns concentrated water from the reverse osmosis membrane device to the raw water tank, and a back pressure control valve provided on the concentrated water line, a control valve for controlling the concentration of the concentrated water from the batchwise concentration of the water;

[0009] [2] The batch concentrator according to [1], wherein the orifices are provided in 2 to 5 stages.

[0010] [3] The batch concentration apparatus according to [1] or [2], in which the reverse osmosis membrane apparatus is installed in series in 2 to 5 stages. Effect of the Invention

[0011] Since the batch type concentration apparatus of the present invention is provided with an orifice on the upstream side of the valve provided in the concentrated water line, sufficient back pressure can be applied to the RO apparatus without excessively reducing the valve lift of the back pressure control valve. Since it is not necessary to excessively reduce the valve lift of the back pressure control valve in this way, clogging of the back pressure control valve is prevented. Although there is a method of suppressing excessively small valve lift by using multiple valves compared to providing a single stage valve, using an orifice can be regarded as a valve with a 100% opening, so providing an orifice is preferable to providing multiple valves. [Brief description of the drawings]

[0012] [Figure 1]FIG. 2 is a flow diagram showing the configuration of a batch-type concentrating apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment will be described with reference to the drawings.

[0014] Raw water (water to be treated) is introduced into a raw water tank 2 through a pipe 1, and a predetermined amount of raw water is stored in the raw water tank 2.

[0015] The water in the raw water tank 2 is pumped out by a pump 5 through a pipe 3 at the bottom, via a valve 4, and is supplied to a first reverse osmosis membrane device (hereinafter sometimes referred to as an RO device) 11 via a valve 6 and a pipe 7.

[0016] The concentrated water of the first RO device is supplied to the second RO device 12 via a pipe 11a, the concentrated water of the second RO device 12 is supplied to the third RO device 13 via a pipe 12a, and the concentrated water of the third RO device 13 is supplied to the fourth RO device 14 via a pipe 13a. The concentrated water of the fourth RO device 14 is sent to the raw water tank 2 via a pipe 15, an orifice 16, a back pressure control valve 17, and a pipe 18.

[0017] Various types of back pressure control valves, such as piston type and diaphragm type, can be used as the back pressure control valve 17. Although not shown in Fig. 1, it is also possible to install pressure gauges between the concentrated water in the last stage of the RO equipment (the fourth RO equipment 14 in Fig. 1) and the orifice 16, and between the orifice 16 and the back pressure control valve 17, to manage the pressure or identify the location of blockage (either the orifice or the back pressure control valve).

[0018] In this embodiment, the orifices 16 are installed in two stages, but they may be installed in one stage or three stages or more (up to about five stages). If there are five stages or more, it becomes complicated to manage the pressure between the orifices, as read from a pressure gauge installed at the end of the reverse osmosis membrane and between the orifice and the control valve, so one to three stages are preferable. As the orifice, a commercially available orifice can be used, but it is not particularly limited as long as it has the function of narrowing the flow path. If the concentrated water contains suspended solids with a particle size exceeding 10 mm, an inflow prevention member such as a punched metal may be provided.

[0019] The permeated water that has permeated the RO membrane of each of the RO devices 11 to 14 is introduced into a permeated water tank 21 via each of the permeated water pipes 11b, 12b, 13b, and 14b and a junction permeated water pipe 20. The permeated water in the permeated water tank 21 is taken out via a valve 22 and a pipe 23.

[0020] A pipe 8 branches off from the pipe 3, and a valve 9 is provided on the pipe 8. The valve 9 is opened only when water (e.g., concentrated liquid) is discharged from the raw water tank 2, and is otherwise closed.

[0021] Materials for reverse osmosis membranes include cellulose acetate, aromatic polyamide, polyacrylonitrile, and composite membranes, and any of these can be used, but when the raw water contains oil or surfactants, cellulose acetate is preferable. Reverse osmosis membrane modules include tubular, disk, flat membrane, hollow fiber, and spiral types, and any of these may be used. Note that tubular and disk types are examples of reverse osmosis membranes that can be set to a high membrane linear flow rate.

[0022] In this batch type concentration apparatus, after a predetermined amount of raw water is stored in the raw water tank 2, valves 4 and 6 are opened and pump 5 is operated. The water in the raw water tank 2 is passed through the first to fourth RO devices 11-14 in sequence via pipes 3 and 7, and concentrated water from the fourth RO device 14 is returned to the raw water tank 2 via pipe 15, orifice 16, back pressure control valve 17, and pipe 18. The permeated water is taken out to the permeated water pipes 11b-14b, 20 and the permeated water tank 21.

[0023] In this embodiment, since the orifice 16 is provided, it is possible to apply sufficient back pressure to each of the RO devices 11 to 14 including the RO device 14 without excessively reducing the valve lift of the back pressure control valve 17. Therefore, clogging of the back pressure control valve 17 can be prevented.

[0024] In the present invention, there is no particular limitation on the raw water to be treated. The present invention can treat wastewater that was difficult to treat with conventional batch-type concentrators, such as CMP slurry wastewater and oil-containing wastewater.

[0025] In the present invention, RO concentrated water can be sufficiently treated even when the water has a surfactant concentration of 1500 mg / L or more, an SS concentration of 14000 mg / L or more, and a CODmn concentration of 10000 mg / L or more. [Explanation of symbols]

[0026] 2 Raw Water Tank 11~14 Reverse osmosis membrane equipment 16 Orifice 17 Backpressure Control Valve 21 Permeation tank

Claims

1. A batch type concentration apparatus having a raw water tank into which raw water is introduced, a reverse osmosis membrane device through which water in the raw water tank is passed, a concentrated water line for returning concentrated water from the reverse osmosis membrane device to the raw water tank, and a back pressure control valve provided on the concentrated water line, The raw water is a CMP slurry wastewater or an oil-containing wastewater, A batch type concentration apparatus having an orifice installed on the concentrated water line upstream of the back pressure control valve, a pressure gauge disposed in the concentrated water line for returning concentrated water from the reverse osmosis membrane device to the raw water tank, between the reverse osmosis membrane device and the orifice, and between the orifice and the back pressure control valve.

2. 2. The batch type concentrator according to claim 1, wherein the orifices are provided in 2 to 5 stages.

3. 3. The batch type concentrator according to claim 1 or 2, wherein the reverse osmosis membrane devices are arranged in series in 2 to 5 stages.

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