AWWA MTC64636

The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR),developed to fulfill requirements set forth in the Safe Drinking Water Act (SDWA)Amendments of 1996, proposes new standards for the removal of Cryptosporidium indrinking water plants in an effort to provide increased public protection from acuteillness. The rule proposes a minimum removal/inactivation requirement of 3 log, withadditional removal required dependant upon the source water concentration ofCryptosporidium oocysts. Although U.S. Environmental Protection Agency (USEPA) Water Supply Guidance documentsindicate that it was not the intent of USEPA to apply surface water regulations toseawater, new data on Cryptosporidium viability in seawater and a trend towards thelocation of seawater facilities in estuarial waters challenge the premise of USEPA'sguidance on seawater. Some primacy agencies have indicated that prudence mayrequire that the LT2ESWTR be applied to seawater desalination facilities treating openwater intakes, particularly if they are located in estuarial waters. As a result, existing andfuture coastal seawater desalination facilities in the U.S. must be prepared to complywith the requirements of the LT2ESWTR. Although reverse osmosis (RO) can be used to achieveCryptosporidium credit, the methods recommended are either technically difficult toachieve, and/or require the system to be taken off-line during the test. In either case,pursuance of Cryptosporidium removal credit for the desalination process is notrecommended. Upon examination of the unit processes typically used for seawaterdesalination pretreatment, it appears that more than adequate removal credit will beachieved for bin 1 and bin 2 waters. A more advanced treatment process, or aconventional process that produces particularly excellent water, may be grantedsufficient credit to comply with bin 4 requirements, in such an event source watermonitoring is not required for the facility. Includes 20 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

03/01/2007

Number of Pages:

15

File Size:

1 file , 540 KB