Challenge

Over a decade after going online as the largest low-pressure membrane system in the world, the first in Wisconsin and first direct membrane filtration process on Lake Michigan, the Kenosha Water Utility’s (KWU) 22-million gallon per day (MGD) microfiltration membrane plant can boast of satisfaction as an early adopter of new technology and hundreds of visitors worldwide who've toured the facility.

KWU built the membrane plant to update a 40-mgd conventional treatment facility, consisting of the original 20-mgd “west plant” from 1895 upgraded to a conventional filtration plant in 1917 plus a 20-mgd “east plant” built in 1964. After evaluating several options, and following Milwaukee’s 1993 Cryptosporidium outbreak, the utility decided to upgrade its east plant and replace the west one with a new membrane filtration system.

Solution

KWU settled on a Memcor® pressurized membrane system for the new plant. While the final installed cost turned out to be $10 million less than projections for replacing the west plant with a comparable conventional process, the utility’s decision to become a membrane pioneer was motivated by a sincere desire to provide the highest quality of water possible for its customers. Its vision has been confirmed every day since the membrane plant’s start up in December 1998 by producing high-quality potable water that meets all USEPA and Wisconsin Department of Natural Resource drinking water requirements.

Results

Since the plant became operational, though, KWU's demand for water has evolved while operations and maintenance methods have improved along with membrane quality and replacement options. Lessons learned include the value of regular membrane integrity testing, scheduled chemical cleaning, preventative maintenance, staff training, financial planning and a positive rapport with regulatory agencies.

Several of Kenosha’s largest industrial customers have left the area, reducing water demand. Today, KWU operates the plant at a higher rate through the night, taking advantage of reduced electrical load charges while replenishing storage tanks within the distribution system, and then coasting during the day.