Engineering bottom ash pellets for phosphorus removal from water: Performance evaluation and economic assessment

• Engineered bottom ash pellets (BAP) were developed for phosphorus removal. • Thermal and additives modification improved BAP adsorption capacity. • TEA confirmed BAPs as a cost-effective solution for phosphorus removal. • Scaled-up BAP systems demonstrated a long lifespan and low treatment costs. This study investigates the development of engineered bottom ash pellet (BAP) and evaluates its phosphorus removal performance and economic viability intended for field-scale applications. BAP was produced by blending coal bottom ash (CBA) with clay and lime, followed by thermal treatment. Bench-scale experiments showed that modification of CBA to BAP improved the phosphorus removal efficiency from 34 % to 95 %, with a maximum adsorption capacity from 19. 56 mg/g to 56. 6 mg/g. Phosphorus removal followed a pseudo-second-order kinetic model (R² = 0. 99) and fit well with the Langmuir isotherm (R² = 0. 98), indicating chemisorption as the dominant mechanism. Economic analysis estimated the BAP production cost of 118 to 261/ton, with labor and operational time identified as key cost drivers. Scaled system evaluation demonstrated that BAP offers long service life and cost-effective phosphorus removal in both municipal and agricultural applications.