Putting Bacteria on the Hot Seat

The plant’s current water treatment process included pre-filtration, carbon purification, ultraviolet (UV) sterilization and 0.5-micron (µm) final filtration. The system was fed with city water, and the flow was directed to several points of use in the facility. Sanitization was a time-consuming chemical process, and the normal backwashing and sanitization routines did not produce the desired results.

The manufacturer wanted a protocol that would ensure less than 10 cfu/ml bacteria counts on a day-to-day basis, resulting in a clean carbon bed.

Plant personnel researched several treatment processes, and chose heat optimized technology for its process improvements and the reduced operating cost of sanitizing the carbon media in backwash mode. By using the HOT process, the production plant would save 4,500 gallons of water per day (based on a daily backwash regimen). It purchased a complete turnkey recirculating water system, which included a 5-µm pre-filter, a HOT carbon tower, a UV system and a 0.45-µm final filter. The water treatment package was designed to automatically be hot water sanitized along with the distribution loop within a one-and-a-half-hour window.

The new system was installed in a research and development facility to feed a new sanitary-designed recirculation loop. The system had a constant available flow of 150 gallons per minute, while maintaining a loop velocity of five feet per second.

After the system was started up, organism counts were closely monitored, and maintained within specified limits for the desired time period before sanitization was required again. Micro counts were well below specification maximums. In addition, water use decreased by 75 percent, and the plant was able to eliminate the use of sanitization chemicals.

Ensuring Quality

When a dairy that manufactures milk, ice cream and juices wanted to introduce a high quality bottled non-carbonated beverage with a long shelf life, it first had to make sure its water treatment system could remove chlorine, chloramines, taste and odors, with low microbial counts. It also wanted to ensure that its carbon stayed clean and sanitary.

The dairy installed a HOT carbon tower with a flow rate of 1 gallon per minute per cubic feet of carbon. The system was customized so that the polishing cartridge filter is sanitized on a daily basis in just 20 minutes.

Twice a week after the day’s production, plant operators automatically initiate the backwash and sanitization mode. The system is reducing organism counts to less than 1 cfu/ml. It consistently removes chlorine and produces water that is clear and free of sensory concerns.

When a soft drink plant experienced difficulty in maintaining very low THM levels in its water, the plant found that using HOT technology allowed them to consistently remain below 15 ppb, and also extended the period between steam stripping. It saw a significant increase in quality, cost savings and water savings, and reduced wastewater to the drain.

Harry DeLonge is a consultant for USFilter’s Food & Beverage Market Team. He can be reached at [email protected].