No doubt, that RO is one of the greatest developments of 20th century to serve for mankind. RO has many Direct and Indirect advantages for Desalination, Water Purification, Effluent Recycling, etc. over traditional treatment methods.
Pre-requisite for continuous and consistence RO functioning.
RO membranes are having very small pore size that even salt molecules cannot go through. The roll of RO membrane is rejection of dissolved solids like salts. If the membrane is loaded with an additional load for removing suspended solids, membrane gets over loaded and do not function satisfactory.
It is typically called 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 cases the filtration is looked only as the recurring cost, so obviously cheapest elements are selected. Are these cheap elements really economical alternate?
If micro filter is to be looked as, one of the element of the complete filtration process e.g. in RO as pre treatment, for Pharma application pre filtration to membrane, etc.
Then in all the cases inefficiencies of pre filtration is to be borne by final filter elements. In case of PP filters as a final filtration e.g. mineral water, cold drink, etc. application this inconsistency reflects as inconsistency in final product quality.
In this of complete filtration system as a whole and micro cartridge as a part of it, drawbacks of inconsistent quality reflects in complete operation.
In the case of RO this reflects as –
- 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).
A criterion for the 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,
- Any other.
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 the 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 hold particles. This leads of inconsistent filtrate quality within the service life of cartridge. Please see the graph mentioned in "bonflow" Vs PP Literature.
To avoid this offshoot many of the time, quality conscious peoples replace the elements well before it gets chocked. This may leads to the inconsistent quality ultimately resulting into higher cost to the service.
To overcome all these ill advantages vats is offering "bonflow" filter elements so as to get consistent quality and higher dirt holding capacity at the same quality throughout the service life of cartridge. Resulting into the Optimum selection for economizing the micro filter selection.
Advantages of using Vats make "bonflow" cartridge in RO feed water -
The contamination in water for RO feed water is chemically dissolved impurities and suspended solids. Generally due care is taken while delivering the RO for all chemical contamination. By using Vats "bonflow" you can get water with SDI less than 5 and well within the limit as per manufacturers recommendation.
This reduces the cleaning frequency
Increase the life of membrane,
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.