Once on the ground, water contacts and dissolves additional substances. For example, surface waters like lakes, rivers, and streams become murky from soils. Ground waters such as wells and aquifers dissolve and contain hard minerals. Other substances found in water include bacteria, fertilizers, and insecticides.

All water supplies have varying characteristics, and the source of the water will affect those characteristics. Ground waters generally contain higher levels of hard minerals, while surface waters from rivers and reservoirs tend to contain lower mineral concentrations.

Regardless of the source of the water, the potential for water-related problems exists. Those problems could include scale formation, objectionable tastes and odors, sediment, and slime growth. Knowing your water and taking preventive steps helps ensure trouble-free ice production for your customers.

Every ice machine is subject to water-related problems. A filtration system will optimize the equipment’s performance and help ensure the production of a healthy and safe product. Proper water treatment involving appropriately selected filtration helps eliminate water-related problems.

SCALE CONTROL

Scale is a common problem in ice machines. Even though the water is not heated, hard minerals tend to concentrate in unfrozen water and precipitate out on the freezing surfaces. This can restrict tubes, orifices, and valves.

Ice in a scaled machine tends to stick to the scale, jamming the machine and stopping production. Scaling conditions in a commercial ice machine result in higher energy costs, lower ice production, and costly breakdowns.

The best way to solve this problem is to treat the water with specialized, slowly soluble, food-grade polyphosphates (such as 6R Micromet). Specialized polyphosphates keep scale-forming minerals in solution so that they can be removed via the dump or bleed cycle, thus preventing scale formation.

TASTE, ODOR CONTROL

The taste and odor of water has a major impact on the quality — and ultimately on the quantity — of ice produced. The taste and odor of ice can be affected by a variety of factors, the most common of which is chlorine.

Municipalities routinely chlorinate water supplies to protect drinking water from waterborne algae and bacteria. Chlorine is effective at killing harmful bacteria, but it is frequently the cause of undesired tastes and odors.

Other sources of taste and odor include earthy, woody, or fishy smells, gasoline or hydrocarbons, synthetic organic chemicals (including pesticides and herbicides), and volatile organic compounds like hydrogen sulfide (“rotten egg” odor).

The most common and effective treatment to prevent taste and odor problems in ice production is the use of activated carbons. These can include powdered, granular, and carbon block technologies.

Activated carbon media have extensive surface areas and remove tastes and odors from water through the process of absorption, in which the objectionable matter adheres to the surfaces of the activated carbon. All activated carbons have a surface with a texture much like a sponge. The carbon works by absorbing the undesired chemicals in the water.

Studies indicate that all of the forms of activated carbons reduce most or all of the chlorine, but vary in their ability to reduce various organic compounds.

Sediment: Sediment removal is simply the filtration of tiny suspended particles that are not dissolved in the water. These particles create poor taste, clog pumps, and enhance lime scale buildup.

These can be effectively re-moved with filtration. Frequently referred to as “prefiltration,” sediment filters remove particles as small as 0.5 micron from the water supply.

Slime growth: Frequently ice machines are troubled by slime and bacteria growth within the machine and the ice. Sources of the bacteria include the water, the air, and the user. It is imperative that the ice — an edible product — be protected against bacteria contamination.

Proper treatment depends on the source of the bacteria. Treatment options range from chemical sanitizers to sub-micron filtration to ultraviolet lights to ozone generators. At a minimum, periodic and scheduled sanitation should be done.

Corrective action: Filtration systems include in-line disposable filters (like the Micro-Plus Series from Nu-Calgon) and cartridge-in-housing filters (like the NP Series).

A cartridge may contain only polyphosphates for scale control, carbon for taste and odor control, filtration for sediment removal, a combination of treatment, or all of the above.

CLEANING UP

Regardless of the type of filtration used, the equipment should be cleaned prior to treatment or filtration.

Use a commercial ice machine cleaner or nickel-safe ice machine cleaner to remove existing scale deposits. Then sanitize the machine with an EPA-registered sanitizer. A clean, sanitized machine gets optimum results from filtration systems.

Leach is product manager at Nu-Calgon, St. Louis, MO. For more information, call 800-554-5499 or visit www.nucalgon.com (website).

Publication date: 03/05/2001