Hydrotech Discfilter: A Simple Retrofit

The City of Camas, Washington’s activated sludge wastewater treatment plant (WWTP) has a maximum monthly capacity of 6 MGD flow.

The Client's Needs

The City of Camas Wastewater Treatment Plant was faced with replacing their existing cloth media disk filters. The existing filters used a pile cloth type fabric that experienced excessive fouling over time. The filter cloth was difficult to clean and maintain. As a result, the WWTP could not maintain the hydraulic capacity through the filters. At the same time, it was necessary for any filter upgrade to fit within the space used by the existing filters. The site needed a solution that would allow them to easily maintain the capacity and performance of the filter media while also fitting within the existing footprint and hydraulic profile of the existing filters. Finally, the site wanted to use the existing infrastructure for the filter system.

The Solution

Gray & Osborne, Inc. designed the filter upgrade based on Veolia’s Hydrotech Discfilter system as part of the Phase 2B improvements project.

The compact footprint and low headloss of the Hydrotech Discfilter system allowed for installation within the footprint of the facility’s existing cloth media filtration system. The Hydrotech media also allowed for easy cleaning and simple maintenance.

Process Description

The existing filters were removed from service and demolished. Minor modifications were made to the filter basins to allow for installation of the new Hydrotech fiters. The Hydrotech system actually allowed the site to use less space than the previous filters at the site and allowed for better accessibility to the units for O&M purposes. The new filters included an innovative Automatic Cleaning System (ACS to accommodate easy cleaning of the filter media. The site is able to quickly connect the ACS to the filters and the control system automatically controls the supplemental chemical cleaning process in order to remove any foulants. The ACS allows the WWTP to maintain optimal capacity of the filter media.

Results

The system has been running effectively since commissioning in 2013. The staff is able to easily maintain and operate the system. The filters have proven to be effective in meeting the effluent performance requirements and the site is able to maintain the required flow through capacity.

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