Airline Arsenic Treatment Residuals Handlings

Project Owner

Liberty Water


Litchfield Park, AZ

Project Overview

Liberty Utilities Airline Arsenic Treatment Facility (ATF) utilizes a coagulation/filtration process for arsenic removal to treat approximately . The original design intended the filter backwash water to be stored in two backwash tanks and the sludge settled in a lamella plate settler while the clear water was sent back to the front of the plant.  From the beginning, Liberty experienced sludge removal problems at the plate settler resulting in sludge build-up in the backwash tanks and in the settler vault.  After various attempts to modify the settler, Liberty eventually decided to bypass it altogether and drain the backwash water directly to the sewer system. This was wasting approximately 280,000 gallons of water per day and impacting the treatment process at Palm Valley Water Reclamation Facility (PVWRF). 

In order to recover as much backwash water as possible, Valentine designed a Sludge Fluidization and Transfer System (SFAT) in the backwash tanks. The SFAT system includes a new sludge pump skid for sludge fluidization inside the backwash tanks and transfer out of the backwash tanks, sludge piping and motorized valves, as well as in-tank floating decanters and exterior decant valves for the decant process.  After sufficient settling time, the decanter removes the supernatant from the backwash tank, sending it to the decant pump station for return to the front of the treatment process. After a set number of backwash cycles, the settled sludge in the backwash tank is fluidized via the sludge pumps and then transferred to a sludge storage vault to be hauled away. This process is under construction and is expected to recover over 98% of water per day.

Unique Project Features

Existing System Optimization

Reuse of Existing Tankage

>98% Water Recovery

Eliminated Load to Downstream WWTP