Although the varied climatic conditions along California's Central Coast, home of Hahn Family Wines, are ideal for the growing of grapes, the water underground, which the vintner uses for closed-loop heat-cleaning of fermenting barrels and bottles, is mineral-rich and scale-producing. Gritty deposits collect and become troublesome with the application of heat.

After years of using salt-based water softening for critical boiler-treatment applications, Hahn Family Wines sought an environmentally friendlier form of water treatment, one free of chemicals, salt, and waste discharge. For its main water supply, it commissioned the installation of a template-assisted-crystallization (TAC) central treatment system.

Physical Water Treatment
TAC falls into a category often referred to as "physical water treatment" (PWT). The primary goals of PWT are to:

• Avoid the use of chemical additives.
• Minimize or avoid discharge water, regenerates, and waste water.
• Avoid pollution and disposal costs.
• Minimize capital costs and ongoing maintenance.

The technology behind TAC treatment systems was developed in Germany about 15 years ago and used throughout Europe before coming to the United States about eight years ago.

TAC media start out as polymeric beads (resin) in the 20-to-40-mesh size range. Catalytically active sites, or templates, are imprinted on the beads’ surface through a batch-coating process.

PWT works by changing the physical characteristics of a solution, with little or no change in the solution's chemical composition. PWT is used chiefly to reduce water hardness (calcium carbonate) in plumbing systems, appliances, and equipment (boilers, water heaters, dish washers, automotive- and process-washing equipment), valves, and other components that generate or use heated water.

Most PWT devices promote hardness crystallization in a bulk solution to prevent scale formation on downstream surfaces.

TAC is technology that influences a water solution at localized sites (on the media surface) so that hardness ions and their counter-ions (bicarbonate) combine to form inert nanometer-size "seed crystals." Called nucleation, this is the process by which dissolved molecules or ions dispersed throughout a solution gather to create clusters in the submicron size range.

The sum of the seeds provides an enormous area for preferential growth of remaining hardness ions still in solution. Making use of the phenomenon of low-energy heterogeneous transfer, by which solubility shift is achieved, the remaining dissolved ions attach to the seed crystals and continue harmlessly downstream, eventually to be consumed or drained.

Although there is no flow to drain in closed-loop boiler systems, TAC has been successful in controlling scale while reducing or eliminating chemical additives in systems that incorporate a bottom blowdown with scheduled daily discharges.

TAC is the mechanism behind biomineralization—the growth of bone structures in the human body—and commonly is used by pharmaceutical companies to create medicines.

TAC media were submitted to DVGW (German Technical and Scientific Association for Gas and Water), whose standard W 512 is considered the most rigorous and challenging accredited standard for certifying PWT systems for scale-reduction efficiency. The media achieved a scale-prevention efficiency of more than 99 percent for both recirculation-hot-water and single-pass-cold-water protocols.

Used in an upflow design, TAC media are not subject to low-flow channeling or high-flow pressure drops. Pressure drop at peak flow rate is less than 4 psi. Like other resins, the media are subject to water-chemistry limitations, such as chlorine, iron, manganese, tannins, and pH.

The effective life of TAC media is three years and is dependent on neither the volume nor the hardness of water.