What is osmosis?
Osmosis is the movement of molecules through a partially porous permeable membrane, which goes from a region of lower concentration to another one of greater concentration, in this action, the membrane tends to match the concentrations on both sides. This flow of solvent particles towards the area of least potential is known as osmotic pressure measurable in terms of atmospheric pressure.
What is the Reverse osmosis?
If we use pressure higher than the osmotic pressure, an effect contrary to osmosis can be achieved, by pressing fluids through the membrane and only the lower weight molecules pass from the other side. In the treatment of water, the solids dissolved when generating this pressure are retained in the membrane and only the water passes, this is called reverse osmosis it is used for both household and industrial basis the plant or system which is used for industrial basis is known as industrial Ro plant. To achieve this effect of the passage of water it is necessary to pressurize the water to a value higher than the osmotic pressure.
How much water rejects reverse osmosis?
Reverse osmosis membranes have the characteristics of making a continuous cleaning while working because otherwise, they would suffer an accumulation of pollutants and saturation in a short time, so that part of the incoming water flow drags contaminants salts and minerals. This is known as rejection water, which is commonly 40% product water and 60% rejection water, in equipment with relatively good quality water, it can be 50% / 50% or in waters with total dissolved solids ( TDS) low up to 60% / 40%.
What lifetime has reverse osmosis?
A reverse osmosis membrane in a properly designed equipment, the duration can be between 3 to 5 years. It is important to perform periodic maintenance with membrane cleaning chemicals, following the manufacturer's advice. In waters with high concentrations of dissolved solids, hardness or presence of silica it is advisable to dose an antifouling by means of a pump, the pre-treatment that incorporates the equipment is also important: removal of suspended particles through sediment cartridges or bed equipment deep and activated carbon equipment and softeners, if required. In membranes of domestic use, the lifetime is shorter 2 to 3 years because it is not possible to perform the aforementioned maintenance.
Cleaning of Reverse Osmosis membranes:
The fouling of membranes is a normal phenomenon in reverse osmosis (RO) systems. It is reversible when a chemical cleaning is done correctly and on time, and it is not in the opposite case.
The signs that indicate chemical cleaning is necessary are:
· When the permeate flow decreases by 10 to 15%.
· When the pressure differential increases from 10 to 15% the pressure differential, calculated from the pressure in the feed flow minus the pressure in the rejection flow.
· When the rejection of salts decreases between 1 and 2% (this is calculated with the feed and permeate flows, and with the concentration of total salts dissolved in both).
The frequency with which it is required to clean the membranes of
OI depends on:
the concentration of salts in the feedwater, the correct pretreatment of the same and the percentage of rejection with which the equipment is operated. An acceptable cleaning frequency is between 3 and 12 months.
The fouling may be due to:
· Carbonates, sulfates and / or silicates.
· Metal oxides of iron, manganese, aluminum, etc.
· Organic material.
· Biological matter (growth of bacteria, mold, fungi, etc.).
In the case of the first two groups, fouling is due to the precipitation of these salts, which is higher as their concentrations are closer to the limit of solubility in rejection.
For further information click here: Ro plant price in Pakistan
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