US 12,059,637 B2 · Apparatus and method to prevent downward flow of liquid during a gas only washing cycle

Abstract

Devices and methods associated with these devices for significantly reducing or eliminating liquid (e.g., water) in a water or wastewater treatment unit above the underdrain from moving downwardly into the underdrain during an air only wash cycle of the treatment unit. The treatment unit can take many forms including but not limited to an upflow filter and a downflow filter. The treatment unit may include a filter bed having one or more layers of filter media supported by gravel above the underdrain. The treatment unit may also include an underdrain having a porous plate, slotted plate or slotted upper structure that obviates the need for gravel. Positive pressure is provided to the underdrain to overcome the downward force of the driving head in the treatment unit to significantly reduce or prevent liquid present in the treatment unit above the underdrain from moving downwardly into the underdrain.

Claims18

Dependent claims

A method of washing a liquid treatment unit having a compartment housing a bed of granular media above an underdrain, comprising the steps of:

during a gas only phase of a washing cycle, directing a gas into and upwardly through the underdrain into the bed of granular media, wherein in the gas only phase of the washing cycle a volume of liquid is present in the underdrain and a volume of liquid is also present above the underdrain in the compartment housing the underdrain and the bed of granular media;
and,
during the gas only phase of the washing cycle, directing a liquid into the underdrain to create a predetermined pressure in the underdrain to substantially counterbalance a downward force exerted by the volume of liquid in the compartment above the underdrain to prevent liquid from the volume of liquid in the compartment above the underdrain from flowing downwardly into the underdrain during the gas only phase of the washing cycle.

A method of preventing water present in a water or wastewater treatment unit having a bed of granular media and an underdrain from flowing downwardly into the underdrain during an air only phase of a washing cycle, comprising the steps of:

during the air only phase of a washing cycle performed on the water or wastewater treatment unit having a bed of granular media and an underdrain, directing air into and upwardly through the underdrain and subsequently into the bed of granular media disposed above the underdrain, wherein during the air only phase of the washing cycle a volume of water is present in the underdrain;
and,
during the air only phase of the washing cycle, directing water into the underdrain to replace water displaced from the underdrain during the air only phase of the washing cycle to maintain the volume of water in the underdrain substantially constant to prevent water above the underdrain from flowing downwardly into the underdrain during the air only phase of the washing cycle.

Dependencies are inferred from the claim text.

Apparatus and method to prevent downward flow of liquid during a gas only washing cycle

Life of this patent

Apparatus and method to prevent downward flow of liquid during a gas only washing cycle

Life of this patent

Abstract

Claims18