Hello Dears,
I would like to ask you, what is the pressure that we need to apply at the inflow to a reverse osmosys treatment in order to remove chlorides (from 1200 ppm to 500 ppm, so around 60% reduction). Water to treat, is the effluent from an UF tertiary treatment of a biological treatment plant, and contain also around 300 mg/lt of COD (mostly polyphelons).
Thank you
Best regards
In general, reverse osmosis requires a pressure ranging between 20-40psi. In case of specific ion or molecule removal, the pressure counts to be in the range of 80-600 psi pressure unlike conventional mechanism. As we know that RO is one kind of pressure driven diffusion phenomenon where semi-permeable membrane is used. Moreover, with time lots of microcontaminants along with several molecules & ions retain within the micropores. So in order to overcome the ionic effects as well as the polar/nonpolar nature of the membrane molecules, comparatively high amount of driving force is required than in the conventional process. Accordingly, it is quite efficient in desalination as well, where several mineral components & salt ions are also removed having higher osmotic pressure.
Reverse osmosis filtration uses high pressure (100–800 psi) to force water through a semi-permeable membrane that filters out dissolved ions, molecules, and solids (nano-filtration). This process can both remove micro-biologic contamination and desalinate water.
Reverse Osmosis is the one process that can reduce the most amounts of dissolved solids (TDS) and salts including augmenting chloride removal from water. The process of Reverse Osmosis Systems consists of pressurizing water through a semipermeable membrane for high quality water. As high pressure is applied on the feed water, the finely pored filter captures all major contaminants and only allowing water molecules to pass through. The permeate water from this water treatment system contains about 90-95% less TDS and salt particles; making it one of the cleanest and highest quality forms of water. Water produced by a reverse osmosis system contains the lowest amounts of PPM for as low as 10 PPM. For seawater, Reverse Osmosis would be the most effective solution to combat the concentration of chloride from the salty water.
Distillers are another form of water treatment that use air and heat to get rid of contaminants and bacteria in the water. The heat is used in a boiling process to kill microorganisms of all types. This form of water treatment is more expensive than a Reverse Osmosis system due to the process requiring electricity to generate heat.
Hello Michele Marzi ;
I agree with Subhrajit Mukherjee Ph.D. recommendation. You will need to work in the high-pressure range end to achieve a separation at a reasonable rate. In a lab-scale apparatus you can use up to 60 bar (~880 psi) or even higher, but if you are thinking of a pilot or full scale plant, you need to consider a maximum of 40 bar (~600 psi) according to most of the membrane module´s manufacturers.
Regards.
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