Phosphorous sorption by Filtralite P--small scale box experiment.

Area of Science:

• Environmental Science
• Water Treatment Technologies
• Materials Science

Background:

• Phosphorus (P) removal is critical for preventing eutrophication in water bodies.
• Lightweight aggregates like Filtralite P are explored for P sorption in wastewater treatment.
• Understanding P sorption dynamics and capacity is essential for optimizing wetland systems.

Purpose of the Study:

• To evaluate the phosphorus (P) sorption performance of Filtralite P in a simulated horizontal subsurface flow wetland.
• To investigate the factors influencing P removal efficiency and saturation levels.
• To assess the regeneration capacity of Filtralite P after P breakthrough.

Main Methods:

• A box experiment simulating a horizontal subsurface flow wetland was used.
• Filtralite P was employed as the lightweight aggregate for P sorption.
• Varying inlet P concentrations and hydraulic loading rates were applied.
• P concentrations in the effluent and sorbed P in the material were analyzed.

Main Results:

• Outlet P concentration increased with applied P load after breakthrough.
• High loading rates led to faster saturation (90% in ~150 days), while low rates showed 70-90% saturation after 18 months.
• P removal depended on pH, Ca, and inlet P concentration, but not hydraulic loading rate.
• Sorbed P concentrated at the inlet and decreased towards the outlet and bottom layers.
• Filtralite P maintained high P removal capacity even after Ca leaching.
• Resting periods regenerated sorption capacity, reducing effluent P by 22-53%.

Conclusions:

• Filtralite P demonstrates significant P sorption capacity in simulated wetland systems.
• The material's performance is influenced by operational parameters and P load.
• Regeneration after resting periods enhances the long-term effectiveness of Filtralite P for P removal.