Device Evaluated
"Moltek Series", manufactured by Moltek Environmental, Inc., 76 Sutton Road, Webster, MA 01570, phone: 508.949.6035

System Data
Moltek Series I water stabilizer systems were installed on a cooling tower and chiller system used for process cooling at Continental PET Technologies, Inc., (CPET) Bedford, NH. The Moltek system consisted of a non-chemical device (NCD), a mechanical type unit, installed on the cooling water systems at the CPET plant. The CPET Bedford plant is a plastic moulding operation that uses a cooling tower system to provide recirculated water for machine, compressor, and chiller cooling; and a chiller unit to provide chilled water for mould cooling.

Claims Made
Moltek NCD literature claims that it "minimizes bacterial growth", "rust and corrosion are restrained and kept at very low levels", "existing scale deposits will be removed-no new scale will form", "negligible algae growth", "no biofouling or biological slime buildup", and "microorganism counts are kept at minimum levels" via mechanical agitation of the treated water. The CPET plant was cited in the literature as a successful installation.

History
Two Moltek NCD systems were installed in mid-1994 on the cooling tower and chilled water systems. Makeup was untreated City of Bedford water with the cooling tower system operated at 10 cycles. PCT personnel visited the site in August 1995, and obtained water samples. During the visit, plant personnel noted that they were very concerned about the evident severe corrosion and deposition taking place in both the cooling tower and chilled water systems.

Analytical Data
Laboratory results were obtained as follows on the samples:

Parameter	Makeup	Chiller	Cooling Tower
pH su	6.01	6.24	7.05
total alkalinity mg/l	7	71	65
conductivity mmhos	170	1540	1550
calcium mg/l	6.2	25.0	23.6
iron mg/l	0.04	1.3	0.08
suspended solids mg/l	<1	578	18
total hardness mg/l	19.2	95.0	91.1
saturation index 100 F	-3.52	-1.77	-0.102

A sample of deposited material was obtained from the chilled water system and analyzed. The laboratory reported that the foulant was 84.3% iron hydroxide, "rust".

Discussion
Moltek literature claims that their NCD minimizes scale and corrosion by control of the saturation index using mechanical agitation of the water. The treatment chamber "will enforce a pH saturation in the water at which non-scaling conditions and minimum corrosion conditions are ... maintained". It "affects the solubility of the calcium carbonate in the water by regulating pH and carbon dioxide value." A further claim is made that it precipitates "calcium carbonate and chemicals" from solution so that they can be removed periodically, or filtered from the water.

The means of corrosion control is explained by "corrosion is minimized ... by high mineral concentrations ... and retarded by a thin film of calcium carbonate ... which serves as a cathodic inhibitor."

Bacterial growth is controlled by a "high shear zone (within the NCD)--that physically ruptures" bacteria, "release of kinetic energy in the contact chamber -- producing free radicals" which kill bacteria, and the high mineral concentration resultant from elimination of blowdown that "retards bacteria growth"

The analytical data clearly shows that the makeup water, as well as the chilled and cycled cooling waters, are all very corrosive, having negative saturation index values. We thus would expect both water systems to experience severe corrosion of ferrous metals, with fouling from deposition of corrosion products. This is exactly what has been experienced at the CPET plant, severe corrosion has occurred in the year since installation of the Moltek NCD and fouling with corrosion products, iron hydroxide (rust), has partially blocked much of the piping and the heat exchangers.

Conclusion
Installation of the Moltek Series I NCD at the CPET plant has shown that this particular unit cannot control ferrous metal corrosion in either a closed loop chiller, or a standard open cooling tower, with a corrosive makeup water. This conclusion is based on the observed serious corrosion and deposition problems at the plant.

The claimed ability to control scale formation is also open to question based upon our knowledge of water chemistry. Physical agitation of water, no matter how "strong", has a minimal effect upon various water properties and none upon the factors controlling scale formation. The additional comment in the literature that the unit controls scale by precipitation is interesting in that operation with scale forming waters at high cycles, as recommended, will often put the cooling water into the pH range were calcium will bulk precipitate via carbonate cycle reactions.  These particular reactions have absolutely nothing to do with operation of the device and have been known for over 100 years.