Water Treatment and Purification
There are a lot of pollutants in water that needs to be dealt with. All sources of water can be treated for suspended solids, colloidal particles, odour, etc through steps designed for specific purposes.

Reverse Osmosis

Application

Reverse Osmosis is a process used to reduce the Total Dissolved Solids (TDS) in the water to be treated. These plants are generally used where the feed TDS ranges from upwards of 300 ppm to sea water where the TDS is in the range of 35000 to 45000 ppm. Some Zero Liquid Discharge plants have been designed for even higher feed TDS.

Operation

During Reverse Osmosis (RO) process pressure is continuously applied to the feed stream by a high pressure pump . Feed stream gets divided into a ‘permeate’ stream low in dissolved salts and ‘brine’ or ‘reject’ stream which is high in dissolved salts content. Dissolved salts rejected by the membrane are continuously flushed from the system via brine control and a percentage of feedwater is converted into permeate. The key terms used in Reverse Osmosis are Recovery, Salt Passage and Concentration Factor. Recovery is the ratio of the permeate flow to the feed water flow, Salt passage is the ratio of dissolved solids in the permeate to those in feed water and Concentration factor is the ratio by which the brine stream is concentrated. The most popular configuration of the RO module is the spiral wound configuration and the membranes are of polyamide.