MEMBRANE BIOREACTOR PILOT TESTING AT REDUCED SRT FOR KING COUNTY, WA

This report summarizes the findings of the membrane bioreactor (MBR) pilot tests. The hollow fiber MBR unit, “Zeeweed” manufactured by Zenon Environmental, Inc., was configured to receive West Point WWTP primary influent and West Point WWTP primary effluent. These studies were divided into several phases in order to test several different combinations of parameters as follows:Phase 1a/1c - Nitrification/Denitrification at 10 day Aerobic Sludge Age, 6 gpm.Phase 1b – Nitrification/Denitrification at 10 day Aerobic Sludge Age, 8 gpm.Phase 2a/2b – Nitrification/Denitrification at 6 day Aerobic Sludge Age, 6 gpm.Phase 3a – Biological P Removal at 6 day Aerobic day Sludge Age, 6 gpm flow.Phase 3b – Biological P Removal at 6 day Aerobic day Sludge Age, 9 gpm flow.The focus of these pilot tests was to evaluate the MBR process as a secondary treatment system to produce Class A reuse water. The specific goals for the pilot study were:Achieve effluent ammonia concentrationsAchieve effluent nitrate concentrationsAchieve effluent nitrate concentrationsAchieve effluent turbidityAchieve effluent TPMeet Class A reclaimed water standards.Performance for individual process parameters and ability to meet other study goals is summarized below.