Pre-aeration has been applied over several decades at municipal wastewater treatment plants to improve primary treatment performance. Pre-aeration is also usually coupled with grit removal tanks to provide for efficient grit removal. Several studies in the 1950s by Seidel and Baumann1 and Roe2 documented the benefits of pre-aeration coupled with primary sedimentation over plain settling. Studies by Finger and Parrick3 developed refinements in pre-aeration tank optimization that caused improvements in grit removal efficiency.