Title : From waste to resource: Advancing sustainable phosphorus and nitrogen recovery for net-zero wastewater treatment
Abstract:
Achieving net-zero wastewater treatment requires shifting from traditional removal methods to integrated systems that recover nutrients instead of discarding them. Nutrient-rich Anaerobic digestion (AD) sidestreams, although typically less than 1% of plant flow, can account for up to 40% of Phosphorus (P) and Nitrogen (N) loads, making them strategic hotspots for resource recovery. However, their high alkalinity (3400–4400 mg/L as CaCO?) and complex carbonate equilibria limit the efficiency of phosphorus precipitation and nitrogen stripping technologies. This presentation introduces an integrated model–experiment framework that advances sustainable P and N recovery for circular, low-carbon wastewater treatment. Using iterative equilibrium modeling, we accurately predicted alkalinity neutralization and precipitation windows in real sidestreams, achieving over 90% accuracy between modeled and experimental alkalinity reduction (NSE = 0.92; KGE = 0.87). Guided by the model, optimized Ca²? dosing (36–72 mM) reduced alkalinity to below 1500 mg/L and enabled 80–90% P recovery as struvite and hydroxyapatite in a hydrodynamically optimized crystallizer. Complementing phosphorus recovery, advances in bipolar membrane electrodialysis–membrane contactor (BMED-MC) technology demonstrate efficient N capture, approaching 60% at energy demands lower than 10.3 kWh·kg?¹-N (Haber Bosch). Together, these innovations create a pathway for wastewater treatment facilities to transform AD sidestreams into renewable nutrient reservoirs—supporting nutrient circularity, reducing chemical use, lowering carbon intensity, and advancing the broader transition to net-zero, resource-positive wastewater treatment. Ongoing work is focusing on fouling dynamics in the BMED as studies enter the pilot phase.
