Pre-filtration with Vats "bonflow" – An effective way for Optimizing RO performance.

Reverse Osmosis (RO) is the world’s latest water treatment technology. No doubt, that RO is one of the greatest developments of 21st century to serve for mankind. RO has many Direct and Indirect advantages for Desalination, Water Purification, Effluent Recycling, etc. over traditional treatment methods.

It is typically called membrane fouling. This will result into the reduction in flux i.e. permeate or increase in pressure for same .

Most of the general-purpose applications like Water treatment industries, Drinking Water, etc. uses cheaper option available of cartridges like Polypropylene wound or PP Spun (thermally Bonded PP, etc.)

Many of the time RO pre-filtration is looked only as the recurring cost, so obviously cheapest elements are selected. Are these cheap elements really economical alternate?

Pre-requisite for continuous and consisitent RO Functioning :

Consistent Quality of feed which is pre treated for-

• Suspended Solids (Slit Density Index SDI < 5)
• Chemical Impurities which affects the membrane
• With Anti-scalent

Most of the time chemical impurities are taken care with pretreatment and antiscalent dosing. And for suspended solids any cheap element is used assuming that in case filter doesn’t work, definitely membrane will take care. Lets understand the reality about pre-filtration to RO.

RO Pre-Filtration

Most of the time spirally wound membrane manufactures suggest the input suspended solids to RO < 5 SDI. In cases of any feed with SDI > 5 following possible significant ill effect are unavoidable-

• Fouling / Chocking of membrane
• Frequent cleaning of membrane
• Reduction in flux affects the production scheduling
• Increase in electrical consumption and
• Ultimately earlier replacement (within 2 years)

All above ultimately leads to higher per liter cost of production, may be 2 to 4 times higher than expected/projected.

Criteria for Comparing Different Filter Elements

A criterion for comparing filter elements is, generally, the “life” or service period per replacement of the set. Another, the most important parameter for the filter comparison, is quality of filtered water.

The true comparison for the filter elements should be based on -

• Quality – NTU, SDI, etc.
• Throughput at what quality level
• Consistency within same elements and for consecutive replacement
• Disposal hassles
• Inventory
• Any other

Limitations of Existing PP Filter Elements

For general-purpose application and by mistake, some times for critical application PP spun or PP wound filter elements are used. Generally it is assumed that these are good at start. Initially as per the morphology of cartridge, it holds Particles. As it starts developing some pressure drop it changes its morphology. Change in porous structure (morphology) is the result of elastic nature of PP material. It expands its porous structure after getting pressure, resulting into release of already held particles. This leads to inconsistent filtrate quality within the service life of cartridge.

To avoid this offshoot many of the time, quality conscious people replace the elements well before it gets chocked. This may leads to the inconsistent quality ultimately resulting into higher cost to the service.

Vats "bonflow" a Superior and Economical RO Pre-filtration

To overcome all above-mentioned ill effects, Vats "bonflow" filter elements are the best alternative.

By using Vats "bonflow" you can get water with SDI < 5 and well within the limit as per manufacturers recommendation along with advantages such as

• Reduction in the flushing and cleaning frequency
• Increase the life of membrane (can go up to 5 years)
• Consistency in through-put
• Longer life of Pre filters due to graded density construction

Leads to overall smoothing of operation and ultimately result to COST SAVING.