Pilot-Seeding Studies to Optimize Washwater Reclamation Plant Performance for Cryptosporidium and Surrogate Removal

摘要

The primary objective of this study was to enhance the removal of Cryptosporidiumrnoocysts in Metropolitan’s washwater reclamation plants (WWRPs) through optimizationrnof coagulation/sedimentation processes. Coagulants selected during previous bench-scalernstudies were evaluated in pilot-scale seeding studies at various flow rates and dosages.rnTurbidity, Cryptosporidium oocyst, aerobic spore former (ASF), and particle-countrnanalyses were used to evaluate coagulant performance. Seeding studies were conductedrnwith inactivated Cryptosporidium oocysts in spent filter backwash water to determinernwhether turbidity, ASF, and particle removals can be used as indicators of Cryptosporidiumrnoocyst removal in coagulation/sedimentation studies. A cationic PAM polymerrneffected the best removal of all of the evaluated constituents. Preliminary results indicaternthat ASF and total particle (>2 microns) removal significantly correlated with Cryptosporidiumrnremoval and may potentially be useful surrogates. Cryptosporidium removalrnthrough sedimentation ranged from 0 to 0.98 logs in preliminary tests conducted underrnno polymer, non-optimized, and optimized coagulant conditions.