CZ29426U1 - Device for concentration of solutes by pressure membrane processes - Google Patents

Description

BACKGROUND OF THE INVENTION

Pressure membrane processes are used in a variety of industrial applications, water treatment and wastewater treatment. The methods used can be divided according to the pore size of the membranes used for microfiltration, ultrafiltration, nanofiltration and reverse osmosis, the latter process using so-called non-porous membranes, where diffusion is applied.

In microfiltration and ultrafiltration, particle separation takes place by the so-called sieve effect, where particles larger than the membrane pore are retained and smaller particles pass through the membrane. They are used, for example, in the food industry for stabilization of beverages, whey treatment, in pharmacy for cold sterilization, for production of drinking water and its sanitation and in membrane bioreactors for biomass separation.

Nanofiltration combines the sieve effect with solvent diffusion across the membrane and as a result organic substances and usually polyvalent ions are retained. This feature is mainly used for water softening, pesticide removal in drinking water production, landfill leachate cleaning, waste water purification from organic synthesis and eg for desalination of dyes after diazotation.

Osmosis is a type of passive transport in which the solvent passes through a semipermeable membrane from a space with a less concentrated solution of osmotically active substances to a space with a more concentrated solution of osmotically active substances. The semipermeable membrane is permeable to solvent and impermeable or limited permeability to solutes. The rate of passage of the solvent through the osmotic membrane determines the difference in osmotic pressures on both sides of the semipermeable membrane.

Reverse osmosis is a process where, on the side with a higher concentration of osmotically active substances, a pressure higher than the osmotic pressure of the system is applied, and the reverse effect occurs - solvent transfer across the semipermeable membrane and concentration of solutes.

Reverse osmosis is mainly used in water purification and desalination, in demineralized water preparation and in the ultra-pure water industry in combination with ion exchange technologies, or electrodeionization, preparation of process and rinse waters and solutions, and concentration of products such as maple or birch syrup, fruit juices, or dairy products.

The systems used for the membrane methods are usually made of materials complying with the appropriate hygiene standards, depending on the intended use of the permeate or retentate, but are not suitable for analytical purposes. Especially spiral wound modules with large membrane area in crossflow filtration mode are used.

At the outlet of the membrane process there is then a permeate, i.e. a solvent that has passed through the membrane, and a retentate, which is a solute concentrate.

The essence of the technical solution

The present technical solution provides a device using the principle of pressure membrane filtration, especially suitable for concentrating solutes (solutes or colloids) in an aqueous solution, eg a sample for subsequent environmental analysis, without changing the character of the sample or contaminating or changing the sample material equipment.

The apparatus according to the present invention comprises an aqueous solution inlet with a pump providing the necessary pressure in the system, a tube for conducting aqueous solution from the pump to an inert material cell in which the plate membrane is interchangeably attached, and the cell is provided with permeate outlet and retentate outlet wherein a first manometer is located before the cell entry and a second manometer is provided at the cell retentate outlet followed by a retentate outlet from the device.

-1 CZ 29426 Ul

The retentate outlet may, in one embodiment, be recycled to the aqueous solution inlet for a multiple membrane process.

In one embodiment, a flowmeter is provided downstream of the second manometer, optionally in a branch or bypass after the second manometer.

The system pressure is preferably regulated by a needle valve.

The inert cell material may be, for example, teflon (polytetrafluoroethylene) or stainless steel.

The tubes for conducting the aqueous solution and the retentate are also made of an inert material, for example Teflon.

The plate membrane may be selected from a paper filter and membranes for microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. The plate membrane, especially for reverse osmosis, can be, for example, a polyamide membrane, preferably treated with an aqueous solution of ethanol or isopropanol.

For example, the flow meter may be a float, ultrasonic or paddle flow meter.

The pump is preferably a gear pump. When using a gear pump, there is no need to install a shock absorber, it is well adjustable and has a linear characteristic.

Before the aqueous solution enters the cell, a bypass with a flow-controlled valve may be branched back to the aqueous solution inlet.

In a preferred embodiment, all the components of the device intended to contact the incoming aqueous solution and the retentate are made of Teflon or stainless steel, with the exception of the plate membrane and optionally with the exception of the flow meter.

The device according to the present invention is adapted to make it possible to use plate membranes for membrane pressure processes which are easily replaceable and which can be easily adapted to the requirements of a particular process. Furthermore, the proposed device resists well the pressures required for these membrane processes, including those required for reverse osmosis, and allows precise control of the pressure and flow rate of the aqueous solution in the system. It can be assembled in a very compact form suitable for use on a laboratory scale. The inert materials prevent contamination of the incoming solution and retentate, allowing the use of sample concentration devices for very sensitive methods as well as the concentration of highly diluted samples.

Clarification of the drawing

Giant. 1 and 2 schematically show the devices for the pressure membrane processes described in the exemplary embodiment.

Example of technical solution implementation

The pressurized membrane process apparatus schematically shown in Fig. 1 comprises an aqueous sample tank 1 from which the aqueous sample enters the system. The system includes a Verder VGS120 gear pump (VERDER sro, Czech Republic) controlled by an OptiDrive 0.75 kW frequency converter, as well as teflon tubes for conducting a water sample from pump 2 to a teflon 4 CF042 Crossflow Cell Assembly (Sterlitech Corporation, WA, USA). with a removable plate membrane. The cell 4 is provided with a permeate outlet leading to the permeate tank 9 and a retentate outlet, wherein a first manometer 3 is provided prior to the cell entry 4, and a second manometer 5 is provided at the cell retentate outlet, and is guided from the second manometer 5 a Teflon tube for guiding the retentate to the float flow meter 7 via a manual needle valve 6 to control the pressure in the system. The second pressure gauge 5 is followed by a retentate outlet from the device, led back to the tank L Before the water sample enters the cell 4, a bypass with a manual ball valve 8 is led back to the tank 1.

Fig. 2 schematically illustrates a device which differs from the device of Fig. 1 in that the retentate outlet is directed to a retentate tank 10 separated from the aqueous sample tank I.

-2GB 29426 UI

The functionality of this assembly was tested using a Dow Filmtec BW30LE polyamide plate membrane (The Dow Chemical Company, USA) suitable for reverse osmosis, and distilled water. The monitored parameter was the permeate flow through the membrane, the variables being the pressure and flow rate of the incoming water. The membrane pressures tested were in the range of 4 to 10 bar (0.4 to 1 MPa), the inlet water flow rates were tested at 25 and 50 lh ^-1 .

With an active membrane area of 42 cm ² , the actual permeate flow at 10 bar (1 MPa) and the inlet water flow rate was 25 lh ^{-1 of} 0.18 lh ^-1 , or 43.9 l h -1 ^l m ^-2 . However, the unit permeate flow rate can be accelerated by suitably treating the membrane, for example by treating with a 50% (v / v) ethanol solution. The flow efficiency across the treated membrane increased by an average of 5.4 liters / m ² independent of the pressure tested.

Collective characterization of equipment efficiency with 50% EtOH membrane:

1) At an inlet water flow rate of 25 l h ^-1 and a pressure of 4 bar (0.4 MPa), the flow was through the membrane

19.8 l h''m ^'2, and it increased to 48.7 H ^ m' ² at 10 bar (1 MPa) and the same flow rate 25 l h ^'first

2) At an inlet water flow of 50 lh ^-1 and at a pressure of 4 bar (0.4 MPa), the flow was through the membrane

13.8 lm- ² , and this increased to 40.8 lh-m- ² at 10 bar (1 MPa) and the same flow rate of 50 l-h- ¹ .

Claims (10)

PROTECTION REQUIREMENTS Apparatus for concentrating solutes by pressure membrane processes, characterized in that it comprises an aqueous solution inlet with a pump (2), a tube for conducting the aqueous solution from the pump to the cell (4) of inert material in which the plate membrane is interchangeable; the cell (4) is provided with a permeate outlet and a retentate outlet, wherein a first manometer (3) is provided before the cell entrance (4), and a second manometer (5) is provided at the retentate outlet from the cell (4), followed by retentate output from the device. Device according to claim 1, characterized in that the inert material of the cell (4) is teflon or stainless steel. Device according to any one of the preceding claims, characterized in that the tubes for conducting the aqueous solution and the retentate are made of Teflon. Device according to any one of the preceding claims, characterized in that the plate membrane is selected from a paper filter and membranes for microfiltration, ultrafiltration, nanofiltration and reverse osmosis. Device according to claim 4, characterized in that the plate membrane is a polyamide membrane, preferably treated with an aqueous solution of ethanol or isopropanol. Device according to any one of the preceding claims, characterized in that the pump (2) is a gear pump. Apparatus according to any one of the preceding claims, characterized in that it further comprises a needle valve (6) for regulating the pressure in the system. Device according to any one of the preceding claims, characterized in that before the aqueous solution enters the cell, a bypass with a flow-controlled valve (8) is branched back to the aqueous solution inlet. Device according to any one of the preceding claims, characterized in that a flowmeter (7) is arranged downstream of the second manometer (5), optionally in a branch or bypass after the second manometer (5). -3GB 29426 U1 Device according to any one of the preceding claims, characterized in that the retentate outlet is led back to the aqueous solution inlet.