Abstract: A media retention plate for an underdrain system having one or more filter blocks. The plate can include a first slot configured to allow the passage of air and a second slot configured to allow the passage of water during an air backwash. The media retention plate is configured to facilitate the water to flow back into the one or more filter blocks through the second slot while maintaining air flow through the first slot to create an optimal collapse pulse. The first and second slots are evenly sized and evenly spaced apart to facilitate the creation of a relatively smaller-sized collapse pulse during a sequential air-water backwash. A plurality of inserts can be arranged along a perimeter of a basal portion of the bottom surface of the media retention plate. The inserts improve the structural integrity of and prevent uplift of the media retention plate.

Abstract: An electrocoagulation reactor (ECR) apparatus and methods of using the ECR apparatus in the treatment of a fluid stream. The ECR apparatus includes a noncorrosive cylindrical cell housing a plurality of horizontally stacked electrode plates. The electrode plates are held in a pair of grooved, crescent shaped non-conductive inserts. The ECR apparatus further includes two end flanges each having integral flow diverters to facilitate a continuous single serpentine flow of the fluid in the cell. The ECR apparatus further includes a single flow inlet and single flow outlet.