Near-Complete Phosphorus Recovery from Challenging Water Matrices Using Multiuse Ceramsite Made from Water Treatment Residual (WTR)

Water Res X. 2024 Oct 21:25:100267. doi: 10.1016/j.wroa.2024.100267. eCollection 2024 Dec 1.

Abstract

Water treatment residual (WTR) is a burden for many water treatment plants due to the large volumes and associated management costs. In this study, we transform aluminum-salt WTR (Al-WTR) into ceramsite (ASC) to recover phosphate from challenging waters. ASC showed remarkably higher specific surface area (SSA, 70.53 m2/g) and phosphate adsorption capacity (calculated 47.2 mg P/g) compared to previously reported ceramsite materials (< 40 m2/g SSA and < 20 mg P/g). ASC recovered over 94.9% of phosphate across a wide pH range (3 - 11) and generally sustained > 90% of its phosphate recovery at high concentrations of competing anions (i.e., Cl-, F-, SO4 2-, or HCO3 -) or humic acid (HA). We challenged the material with real municipal wastewater at 10°C and achieved simultaneous phosphate (>97.1%) and COD removal (71.2%). Once saturated with phosphate, ASC can be repurposed for landscaping or soil amendment. The economic analysis indicates that ASC can be a competitive alternative to natural clay-based ceramsite, biochar, or other useful materials. Therefore, ASC is an eco-friendly, cost-effective adsorbent for phosphate recovery from complex waters, shedding light upon a circular economy in the water sector.

Keywords: Eutrophication; Sips isotherm; adsorbent; circular economy; nutrient recovery; sludge valorization; waste valorization; water treatment.