Reverse Osmosis



What is Osmosis?


It is a process in which pure water flows from a dilute solution through a semi-permeable membrane to higher concentrated solution. Semi-permeable means it allows small molecules and ions to pass through it but does not allow larger molecules or dissolved substances.

What is Reverse Osmosis?

As the name suggests, this process is reverse as compared to Osmosis. To carry out the Reverse Osmosis more pressure has to be applied on the side with concentrated solution which forces the water molecules across the semi-permeable membrane to the fresh water side.



Industrial Reverse Osmosis (IRO)

Osmosis, when used for industrial purposes is called IRO. IRO is becoming increasingly popular due its effectiveness and cost-efficiency.

IRO has to be customised perfectly for the type of industry wherein it is to be applied. Each different type of industry requires most suitable components and system of IRO. Installation of IRO requires experienced professionals with complete knowledge of the system and preferably with good track records and references.

The installation of IRO system is a complex process right from survey of the soil, source of water, requirement of the industry, selection of components and so on. Though the subject is too vast , below are certain basic points to be followed in almost all types of industries.

1. Water Source

The source of ‘feed-water’ ( water to be processed for RO ) has the maximum impact on the overall design of the entire unit of IRO, as it decides number of filtration stages for pre-treatment of feed-water. In order to protect the membranes which are always too expensive, from any possible damage, the water has to be pre-treated. Ground water has generally stable composition and temperature hence it requires simpler pre-treatment process whereas surface water or waste water requires more complex and expensive pre-treatment.

2. Silt Density Index



It is a measurement to decide the level of very fine particles in water. This impurity is often known as “Silt” and it has to be removed read more else it causes fouling of membranes, reduction in efficiency of RO system and increase down time. Even before designing pre-treatment of RO system a SDI ( Silt Density Index) Test has to be conducted. Specific treatment is required to eliminate silt and only expert professionals should be entrusted with this work.

3. Temperature and Flow Rate of water

The rate of water passing through a membrane Flux Rate varies according to the temperature of water. Warm water passes through the membrane quicker than cold water. The design of IRO system and pre-treatment equipment depend mainly on water temperature and flow rate parameters. The size of IRO is determined based on temperature of the coldest potential feed-water.

4. Pre-Treatment



It is a vital process not only to protect the membranes but also for achieving the desired results. E.g. Dechlorination is compulsory in case the feed-water contains Chlorine. Second most common issue is ‘scaling’ from Calcium and Magnesium compounds. These issues must be dealt with for effective RO process.

5. Micro-Biological Contaminants

They cause fouling and decrease of filter capacity of the membranes and deterioration in overall click here productivity of the IRO unit. These impurities hinder the flow of water and they have to be eliminated with specific and most suitable biocides as certain biocides are harmful to the membranes.

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