Archive for January, 2009

Micron Madness

Wednesday, January 28th, 2009

Micron Madness

We’re always asked what micron rating filter should we use.

There are infinite levels of micron ratings.

If a filter removes 1 particle out of 100 of the 5 micron particles, I guess we could call it a 5 Micron filter. It’s not a very good 5 micron filter but after a while in a recirculation system not making up any more 5 micron particles it would help.

Now we can go to the other extreme and say if we have a filter that removes all 100 of the 5 micron particles we have a really good 5 micron filter. Chances are in this instance is that we also probably have a pretty good 1 micron filter. Most of the time we’ll get pretty close to 90 of the 100 one(1) micron particles if we’re getting 100% of the 5 micron.

Over the years we have a recurring complaint from the users of filters of why the ratings can’t be standardized. There have been repeated efforts to standardize resulting in Absolute rated and Beta rated filters. Unfortunately it’s not possible to have standardization because there are too many variables in the real life situations where we have to use filters.

The real super applications of cartridge filters are the pharmaceutical bacterial filters which must remove a fixed challenge of specially grown bacterial and reduce them by a log factor of 6. These are the real performers. They have to work. The tests are rigorous and do give a level of protection from bacteriological contamination. The micron removal ratings of these filters are 0.1 and 0.2 micron. We’re, however, not talking about particles here. We’re talking about living organisms.

The smallest particles the human eye can discriminate are commonly 40 micron. When you get down below 10, 5 and 1 micron filters – these are small particles – you can see a haze. Also at these levels in liquid filtration the particle capture mechanisms are often a result of van der Waals forces which are inter-molecular attractions.

Above 40 microns we can have screen capture which is a very sturdy way to hold particles. The van der Waals forces which work at the lower microns can be defeated by increased pressures – flows – and cause the particles to unload – to be released from the filter and go back downstream. Going back, if we have a 90% effective 1 micron filter at 5 GPM, if we ramp the flow up to 10 GPM, we’ll probably knock the efficiency down to 80% and after a fairly short period of time, the filter will no longer hold those particles. This is now not a good 1 micron filter.

When are asked which micron ratings we should use in a filter, this discussion is the tip of the iceberg. We have just scratched the surface. With past experience as a guide, we can get the right filters for an application. There are many variables which make up micron madness.

You may want to look at the page on our website where we descibe the different types of cartridge filters we have available at: Cartridge Filters

Posted in Technical Information, Water Conservation | 1 Comment »

Water Conservation by Recycling

Wednesday, January 7th, 2009

A Recycling Approach

First Step of Recycling – Lean-Out the Process
This is always the first rule. Lean-Out means to minimize everything in the process fluid. A Lean Process will reduce the load on subsequent clean up. Often, this in itself will significantly reduce disposal costs. The first step of recycling, – Lean-Out the Process.

Once we have a “Lean Process”, we go to three general phases – Analysis, Equipment & Implementation.

In the Analysis phase we determine what is present in the existing feedwater and in other make up solutions. Finally we determine what are the on site requirements and existing equipment required to support the process.

In the Equipment phase we secure all materials and have them installed as required.

In the Implementation phase, we will stay with the equipment On-Site in a thorough start-up. This phase is more important than in other process applications because the solutions are custom designed and have to be fine tuned for on-site process variables.

Factors to consider in Recycling

Reduce Transportation & Disposal Costs
Reduce Volumes – Can Increase Concentrations
Reduce Concentrations – Without Increasing Volumes
Reduce Costs of Disposal by Replacement or Substitution
Reduce Current and Potential Future Liabilities
Reduce Dependence on Disposal Contractors
Reduce Surcharges in Discharged Liquids

Membranes in Recycling

Reverse Osmosis(RO) and Ultrafiltration(UF) are Membrane Cross Flow Technologies and are considered as separator/concentrators. Liquid forced through the membrane is clean “Permeate” leaving the contaminants behind in the “Concentrate”. The contaminants are not removed by membrane processes. They are still at the site. They are still in the system in the “Concentrate”. Whenever using RO or UF, you must consider what to do with the Concentrate. In some instances we concentrate to minimize discharge volumes – the same amount of contaminant but in a reduced volume. In other instances, we use the Permeate of the membrane back in the process as clean make-up fluid. In this case we still have Concentrate and we still have to determine what to do with it.

Posted in Water Conservation | 2 Comments »