Abstract: A method for removal of solids in a water treatment system having multiple filters, each filter comprising an air backwash system and a water backwash system, comprising a series of steps to enable two filters to be in some stage of the backwash process at the same time thereby reducing the time the filter is out of service. The continuous cycling of the backwash method is characterized by a continuous cycle of backwashing that backwashes two filters simultaneously. The backwashing method requires three steps, an air-only backwash, an air/water bashwash and a water-only or rinse backwash. In this method, as one filter is at the water-only backwash stage, the backwash cycle of a second filter is started so that the second filter is air/water backwashed while the first filter is at the water-only backwashed stage.

Abstract: A method for removal of solids in a water treatment system having multiple filters, each filter comprising an air backwash system and a water backwash system, comprising a series of steps to enable two filters to be in some stage of the backwash process at the same time thereby reducing the time the filter is out of service. The continuous cycling of the backwash method is characterized by a continuous cycle of backwashing that backwashes two filters simultaneously. The backwashing method requires three steps, an air-only backwash, an air/water bashwash and a water-only or rinse backwash. In this method, as one filter is at the water-only backwash stage, the backwash cycle of a second filter is started so that the second filter is air/water backwashed while the first filter is at the water-only backwashed stage.

Abstract: An underdrain block for a filter media system for supporting the filter media and distributing air and water backwash. The underdrain block comprising a top wall, a bottom wall and two side walls forming an open ended interior. Interior walls, known as lateral separation walls, divide the interior of the block into primary and secondary laterals. When the blocks are laid end to end, the laterals form a common distribution conduit for the transport of air and water backwash. The lateral separation walls can be angular or curved. Curved walls and specifically angled walls increase the area of the laterals. The spacing of the blocks can be approximately 18 inches and the height approximately 8 inches. The underdrain blocks are interlocking to form conduits of up to 40 feet in length.

Abstract: A grout-gripping anchor for an underdrain block to be grouted to a filter floor is disclosed. Underdrain blocks have ribs extending outwardly from the exterior walls. The anchor is formed at the distant end of ribs positioned on the bottom exterior wall. The end of the rib widens to form one or more flanges or ledges so that grout covers the ledge when the underdrain block is grouted onto the filter floor. The anchor can be comprised of various shapes, including wedge-shape, rectangular shape or donut shaped.