Leveraging Water Reuse to Solve Multiple Challenges

To improve long-term water supply resiliency and water quality in the Chesapeake Bay, Anne Arundel County’s Our wAAter Program is evaluating multiple management strategies to reduce nutrients and provide enhanced water supply options to the region. 

One piece of this strategy is to evaluate the feasibility of performing Indirect Potable Reuse by adding Advanced Water Treatment processes to its Patuxent Water Reclamation Facility. The AWT would further treat wastewater effluent to national drinking water and potable reuse water quality standards for Managed Aquifer Recharge. MAR is a type of IPR for groundwater replenishment, where highly treated water is injected into nearby aquifers to provide long-term storage and recovery of potentially strained aquifer systems.

Finding the Best AWT Process for Inland IPR

Conventionally, membrane technology has been used on the West Coast for direct and indirect potable reuse. However, installing membrane technology can result in high capital and maintenance costs. Additionally, the membrane concentrate that contains high concentration of solids and salts needs further treatment and disposal. This treatment of the concentrate can be highly cost-intensive for inland locations where direct discharge to ocean is not feasible. 

Carbon-based treatment processes such as ozone, Biologically Active Carbon Filtration and Granular Activated Carbon have the potential to meet the same finished water treatment goals at reduced capital and maintenance costs while providing robust treatment for contaminant removal.  

Validating a Carbon-Based Treatment Process for MAR

To validate the feasibility of using the carbon-based treatment system, an AWT pilot has been installed at the Patuxent Water Reclamation Facility. This AWT pilot began operation in October of 2022. The pilot train is testing five non-membrane processes by treating tertiary effluent with coagulation/flocculation sedimentation; ozone (and ozone-advanced oxidation processes); BAF; GAC; and UV disinfection.

A Sustainable Solution in Sight

The validation process will involve demonstrating compliance with national drinking water standards and potable reuse guidance, including adequate pathogen removal and removal of emerging constituents such as pharmaceuticals, personal care products and PFAS. Additionally, the pilot team is tracking finished water quality and geochemical compatibility for future aquifer injection.

Thousands of samples will be collected during the AWT pilot to demonstrate robust treatment and identify any areas for improvement. Results from this pilot testing will help validate the carbon-based treatment train for MAR as the County considers moving forward with demonstration-scale implementation.