AWWA MTC53815

Cryptosporidium and other chlorine resistant microorganisms are a problem forwater utilities worldwide. New legislation in the United Kingdom requires thatall water supplies at potential risk of contamination must have either anabsolute barrier, in the form of membrane treatment, or that continuous samplesover a 24 hour period must be taken and analyzed for Cryptosporidium.YorkshireWater Services, one of the large private water companies in the UK, awarded a $20million contract to Earth Tech Engineering for the design and construction of a24 million gallons per day (mgd) ultrafiltration plant to supply the city of Hullin the North of England. The plant at Keldgate treats water from 4 boreholes thatare prone to intermittent microbial contamination, particularly after heavyrainfall. Although no outbreaks of Cryptosporidiosis have occurred, the sourcesare potentially at risk. To ensure that the barrier to Cryptosporidium ismaintained, membrane integrity testing is essential. The system chosen atKeldgate is an on-line system, using a dose of powdered activated carbon tochallenge the membrane while monitoring the particle count on the permeate. Thelog removal achieved is then calculated. The advantages of this system, incomparison with other methods available, are discussed. Construction started inOctober 1999, commissioning in August 2000, and the works entered supply inNovember 2000. The commissioning program and experiences encountered arediscussed. The results of the membrane integrity testing and takeover tests areincluded along with the initial operating experience. Includes 3 references, tables, figures.