STORMWATER QUALITY IMPROVEMENT BY AN ALUMINUM-BASED WATER TREATMENT RESIDUAL-INCORPORATED HIGH FLOW MEDIA PLUNGE POOL
Water treatment residual (WTR) is byproduct from the drinking water treatment process; WTR is made of aluminum-based or iron-based chemicals. It has been demonstrated as an advanced material to enhance phosphorus removal from stormwater runoff. In this field study, an aluminum-based WTR-incorporated high flow media (HFM) plunge pool in a residential area was monitored for 14 months to evaluate the removal of total suspended solids (TSS), phosphorus, and nitrogen in stormwater. Results indicate satisfactory removal of TSS, achieved via sedimentation and filtration. Moreover, total phosphorus (TP) concentrations were significantly reduced after treatment. All paired-sample events (13 events) exhibited positive (i.e., effluent EMC < influent EMC) TP removal. However, total nitrogen (TN) was not removed successfully due to 〖〖NO〗_3〗^--N export through mineralization and nitrification processes. Dissolved aluminum leaching is less than 0.05 mg/L. An unexpected effluent seepage with high iron concentrations caused a “baseflow” in the downstream pipe, which was a significant challenge in this project.