Introduction:
Before discussing how a Picosystem works, lets discuss what a Picosystem works on.
Hydro groups contaminates into six general categories: dissolved solids, organics, particulates, microorganisms, microorganism by-products, and dissolved gases. A typical 11218 Picosystem consists of a prefilter housing with a 0.2 micron filter cartridge, activated carbon canister, and two mixed-bed deionizers. It is designed to purify water by means of a series of treatments, each with a fairly specific purpose. Which contaminant does each treatment step address?
Prefilter
The prefilter is a critical part of a Picosystem. Generally, the better the prefilter, the better the Picosystem output quality.
A prefilter can also be a source of contamination. Some membrane prefilters have a wetting agent (surfactant) which coats the surface. This wetting agent must be rinsed off, by flushing the filter. Surfactant not rinsed from the prefilter will pass through the Picosystem and can interfere with some applications.
Note: The Polyethersulfone filters that we now get from Parker are naturally hydrophilic. Hydrophilic filters do not require a wetting agent, so there is none to rinse off from the Parker Polyethersulfone filters.
Activated Carbon
Granular activated carbon is employed to remove chlorine, chloramines and dissolved organics. In doing so, it provides a chlorine-free environment with a lot of nutrient for microorganism growth. Hydro recommends the replacement of carbon tanks every six months to prevent accumulated microorganism and microorganism by-products from overwhelming the rest of the system.
Carbon fines, generated during shipping can also be a problem. If the carbon tank is not flushed to remove these fines, when the tank is installed carbon particulates can pass through the system and contaminate the final product.
Mixed-Bed Resins
New resin contains organics from the manufacturing process. If not removed by several regeneration and exhaustion cycles, which expand and contract the beads (like squeezing a sponge), they can contaminate the product water.
Now, how does a Picosystem work?
Deionization is a process involving the removal of dissolved mineral salts. The dissolved salts are preferentially exchanged for other ions that are already on the resin bead. The ions that are already on the resin beads (from our regeneration) are: Hydrogen (H+) on cation beads and hydroxyl (OH-) on the anion beads. So, mixed-bed resin, with Type I anion resin, is capable of removing all ionized species and producing 18+ Megohm H2O.
Conclusion
Tap water contains all sorts of particles, organics, microorganisms, dissolved salts, gasses, etc. The prefilter removes particulates, activated carbon treats chlorine/chloramines and dissolved organics, deionizers remove dissolved solids (salts) and carbon dioxide. Each treatment step is fairly specific in what it removes and one cannot compensate for another’s failure
