Development of advanced adsorption and ion exchange technologies for nutrient recovery and contaminant removal from municipal and combined sewer overflow wastewaters

This study explores advanced adsorption and ion exchange technologies for the removal and recovery of nitrogen and phosphorus from municipal wastewater (MWW) and combined sewer overflow (CSO) wastewater. The growing demand for sustainable wastewater treatment highlights the need for innovative processes that minimize environmental impact while enabling resource recovery. Excessive nitrogen and phosphorus contribute to eutrophication, especially when wastewater is discharged without adequate treatment. CSO discharges, in particular, pose severe environmental risks due to high contaminant loads and untreated releases during heavy rainfall events. For MWW treatment, G13 geopolymer demonstrated superior ammonium adsorption, with a maximum capacity of 37 mgN g⁻¹ and the ability to treat 200 bed volumes (BVs) before reaching regulatory limits. Its high regeneration efficiency supports sustainable nitrogen recovery. Calcined pyroaurite emerged as the most effective phosphorus sorbent, achieving 12 mgP g⁻¹ capacity and treating 730 BVs before exceeding 1 mgP L⁻¹, complying with EU standards. Phosphate precipitation from the desorbed product confirmed its potential for fertilizer applications. CSO wastewater required different sorbents due to variable contaminant loads. MS13X zeolite effectively removed ammonium, with 18 mgN g⁻¹ of maximum adsorption capacity and sustained efficiency over 230 BVs before exceeding the 15 mgN L⁻¹ threshold. Calcined Sorbacid 911 showed the highest phosphate removal efficiency, achieving 37 mgP g⁻¹ adsorption and treating 400 BVs before reaching 2 mgP L⁻¹. A two-stage system integrating microfiltration and adsorption enhanced contaminant removal, targeting additional pollutants such as heavy metals, PFAS, and pesticides. Further investigations focus on long-term material stability, competitive ion exchange, and optimized regeneration strategies to enhance cost-effectiveness and operational efficiency. The study demonstrates the high potential of adsorption-based technologies for large-scale wastewater treatment, paving the way for improved sustainability and resource recovery. Future research will refine process parameters and explore advanced regeneration techniques to maximize material lifespan and system performance.