Absorption Media Life Testing
Client: Well-known stormwater treatment equipment manufacturer
Background: Our client, a stormwater treatment equipment manufacturer, uses an absorptive media within their stormwater cartridge filtration system. This product removes both sediment-bound and dissolved phosphorus. Phosphorus is a major cause of fresh water algae blooms which can negatively impact water quality. Effects include low dissolved oxygen, fish kills and even public health hazards. Typical applications include commercial, residential and industrial developments, infill projects, ports, roadways and highways.
Problem: Our client needed to accurately determine the lifetime capacity of the absorptive media within their cartridge in order to predict the maintenance requirement of the media and cartridge. This information is crucial to optimum product performance in the field. The state of the art capacity determination is a long term soak test that determines equilibrium, or theoretical, capacity. This does not account for breakthrough, when the filter no longer adsorbs the contaminant during flow even though it has not reached its theoretical capacity. The concept of breakthrough is well known with adsorptive filters in drinking water treatment but has not usually been applied in stormwater treatment. Since the lifetime of a typical filter is supposed to be several years some kind of accelerated test was needed.
Solution: Good Harbour Labs designed a lab procedure it calls ‘Bed Volume Testing’. This involved exposing the media to a certain volume of flow, based on the volume of media, at a rate dictated by the intended application of the media. The test includes rest periods with no flow because adsorptive media have been observed to regenerate some capacity when rested.
Steps Taken: The absorptive media is added to a column at a bed height determined by the typical application of the media. A storm was simulated every 2 hours interval with 45 minutes of flow and a 1 hour and 15 minute rest period. One storm corresponded to 7 bed volumes. These numbers were based on the typical hydrology for the region where the media was expected to be used. Effluent samples were collected at the last 2 minutes of every storm and analyzed. The test was stopped when 10% removal was reached. Bed volume testing can be customized according to the client’s specifications.
Result: GHL was able to provide the client with media and cartridge replacement and lifetime information.
Benefit: The client is able to provide accurate replacement times to their customers to ensure the proper use of their product to achieve optimum results.