Reverse Osmosis (RO) is a membrane based process technology to purify water by separating the dissolved solids from feed stream resulting in permeate and reject stream for a wide range of applications in domestic as well as industrial applications. It is seen that RO technology is used to remove dissolved solids, colour, organic contaminants, and nitrate from feed stream.
Osmosis is a natural process. When two liquids of different concentration are separated by a semi permeable membrane, the fluid has a tendency to move from low to high solute concentrations for chemical potential equilibrium.
Reverse osmosis is the process of forcing solvent from a region of high solute concentration through a semi permeable membrane to a region of low solute concentration by applying a pressure which is excess of osmotic pressure.
Advantage OF RO Water
Water treatment is essential for all dimensions of life. Polluted water is the basic reason behind countless diseases. Apart from basic need of humanity Industrial water treatment seeks to manage following main advantage areas:
DRINKING WATER :-
A good R.O. system with controlled TDS can remove contaminants such as arsenic, nitrates, sodium, copper and lead, some organic chemicals, and the municipal additive fluoride which are harmful for the human body.
BOILER FEED WATER :-
Quality of feed water can cause many benefits-
- Scaling Control (responsible for wet steam production from boiler)
- Corrosion Control (includes boiler and all distribution line accessories)
- Fuel savings
- Dry steam production
RO water is used to prevent scale formation.
RO water is used for:
- Direct injection to maintain hygiene
- Scaling/ Corrosion control (makes life of heat exchanging equipment longer)
PROCESS FLOW DIAGRAM
Pre-treatment may include all/combination of following equipment based on feed water analysis report:
- SAND FILTER
A latest concept in the water treatment technology, a Multi Grade filter consist of vertical or horizontal pressure sand filters that contain multiple layers of coarse and fine sand (pebbles and gravels)in a fixed proportion. It is a kind of deep filter bed with adequate pore dimensions for retaining both large and small suspended solids and undissolved impurities like dust particles.
With high throughputs, high dirt holding capacity and capacity to reduce turbidity and TSS (<5 ppm) from water, it protects ion-exchange resins and membranes from physical fouling due to suspended impurities present in water.
ACTIVATED CARBON FILTER
Activated carbon filtration (ACF) is effective in reducing certain organic chemicals and chlorine in water. It can also reduce the quantity of lead in water although most lead-reducing systems use another filter medium in addition to carbon. Water is passed through granular or block carbon material to reduce toxic compounds as well as harmless taste and odor producing chemicals.
MICRO CARTRIDGE FILTER
Cartridge filters are the machines which is used in filtration purpose by uses the filtration technology of removing solid matter and suspended impurities from a fluid stream by passing it through a variety micro porous filters, ultrafiltration units, green sand cartridge filters, activated carbon cartridge filters, diatomaceous earth and multimedia cartridge filters.
HIGH PRESSURE PUMP
Pump is characterized by its ability to deliver a high constant pressure and a considerable flow. When dealing with water purification, corrosion-resistance is a key word. In connection with membrane techniques, where pressurized raw water flows through a membrane, pumps with special characteristics are needed.
The heart of any RO system is Membrane. The membranes used for reverse osmosis have a dense layer in the polymer matrix – either the skin of an asymmetric membrane or an interfacial polymerized layer within a thin film composite membrane – where the separation occurs.