Phosphate Removal from Water: A Comparison of Adsorbents

Phosphate contamination in water systems continues to pose serious environmental challenges, primarily due to its role in eutrophication and degradation of aquatic ecosystems. Among the various treatment strategies, adsorption has emerged as an effective and versatile method for phosphate removal, even at low concentrations. This review critically examines the performance, mechanisms, and practical applicability of three promising adsorbents: lanthanum-modified bio-ceramisite (La@BC), layered zinc hydroxide (LZH), and bottom ash (BA)—an industrial by-product. Each adsorbent is evaluated based on its synthesis method, adsorption efficiency, interaction with competing anions, and regeneration potential. La@BC, synthesized via co-precipitation, exhibits high selectivity for phosphate and strong performance under acidic conditions. LZH, with its high surface area and structural integrity, supports efficient phosphate uptake and recovery from both synthetic and real wastewater. BA, a low-cost material rich in metal oxides, shows considerable adsorption capacity, as confirmed through Langmuir isotherm modeling (Qₒ = 6.522 mg/g; Rₗ = 0.417). Comparative analysis highlights the trade-offs between cost, environmental impact, and operational efficiency. This review also contrasts these adsorbents with conventional biological and emerging nanomaterial-based treatments, noting that while biological methods offer high removal rates, they require long treatment times and produce excessive sludge. Nanomaterials like nano-alumina offer rapid removal but are expensive and may pose ecological risks. The review concludes by identifying current research gaps and proposing directions for developing scalable, sustainable, and low-cost phosphate removal technologies.