MMF in Purified water generation

Dear forum members,

Kindly guide on Mullti media filter role in the quality of purified water…


Multimedia filtration refers to a pressure filter vessel which utilizes three or more different media as opposed to a “sand filter” that typically uses one grade of sand alone as the filtration media. In a single media filter, during the “settling” cycle, the finest or smallest media particles remain on top of the media bed while the larger, and heavier particles, stratify proportional to their mass lower in the filter. This results in very limited use of the media depth since virtually all filterable particles are trapped at the very top of the filter bed or within 1-2 inches of the top where the filter media particles have the least space between them. The filter run times are thus very short before the filter “blinds” or develops so much head pressure that it must be backwashed to avoid seriously impeding or stopping the flow.

Multi-media filters typically have three layers, consisting of anthracite, sand and garnet. These are often the media of choice because of the differences in mass between the materials. Garnet is by far the heaviest per unit volume, sand is intermediate while anthracite is the lightest. The idea behind using these three media of differing densities is that anthracite media, with the largest particle size, will stratify on top following backwash while the intermediate size media (sand) will settle in the middle and garnet, the heaviest but having the smallest particle diameter, will settle to the bottom.

This filter media arrangement allows the largest dirt particles to be removed near the top of the media bed with the smaller and smaller dirt particles being retained deeper and deeper in the media. This allows much longer filter run times between backwash and much more efficient dirt or turbidity removal. Sand filters typically remove particles down to 25-50 microns while a well-operated multi-media filter may remove particles from 10-25 microns.

Flocculants / coagulants may be used upstream of the filter to induce the tiny dirt particles to join together to form particles large enough to be removed by the filter. This process is called “agglomeration” and, with proper chemical dosage, adequate mixing and adequate contact time, it will enable the filter to remove particles below 10 microns in average diameter.

Dear members,

Kindly inform me what is the recommended temperature of the purified water in the system of pipes for oral solid and liquid dosage forms plant.
What types of valves are recommended? We use spherical type.

Best regards,
PhD V. Dilova

You can run your Purified water plant tank and distribution loop at ambient temperature. No need to run it at higher temperatures. You need to pass the recirculated water and the inlet into water tank should be thru via a UV lamp.
UV sanitation serves the purpose for Water in Oral solid dosages.

The microbial limit is important.The guideline is 100CFU/100ml
You need to have a limit below this limit.
You see WHO guideline – Please look the QA updates as I posted new Water Guideline.

Dear Sir,

According to my knowledge and USP <1231>, water for pharmaceutical purpose, the microbial limits are
Drinking water: 500 cfu / ml
Purified water: 100 cfu / ml
Water for injection: 10 cfu / 100 ml

Pls explain, with documented evidence, if i’m wrong