Phosphorus removal from urban wastewater through adsorption using biogenic calcium carbonate

• Autor(a) principal: Santos, Andreia F.
• Data de Publicação: 2024
• Outros Autores: Lopes, Daniela V., Alvarenga, Paula, Gando-Ferreira, Licínio M., Quina, Margarida J.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/29767
• topic: Eggshell; Equilibrium isotherms; Kinetics; Phosphate; Wastewater treatment

Phosphorus (P) removal from urban wastewater is increasingly relevant in the wastewater treatment sector. The present work aims to contribute to the study of the adsorption process as a P removal technology. Biogenic calcium carbonate from industrial eggshell waste prepared by milling and calcination was used as an adsorbent. Batch adsorption experiments were conducted using real wastewater with 40 mg P/L (orthophosphate), original pH 7.33, under stirring conditions (100 rpm). The adsorbent was characterized using SEM-EDS, XRD, and FTIRATR before and after adsorption. From an initial screening of calcination times (15, 30, 60, and 120 min) and considering a balance between P removal and energy saving, the adsorbent selected was eggshell calcined at 700 ◦C for 60 min. The Langmuir isotherms describe the experimental data with a maximum adsorption capacity of 4.57 mg P/g at 25 ◦C. The adsorption process reached equilibrium within 120 min for different dosages (5, 10, and 20 g/L at 25 ◦C). Batch experiments showed that SO42 , at a concentration of 2689 mg/L reduced the P adsorption selectivity for dosages ≤10 g/L at 25 ◦C. Characterization of the loaded adsorbent shows that P adsorption from real wastewater is mostly electrostatic attraction, with the contribution of ligand exchange and microprecipitation. The adsorption capacity and behavior of the selected adsorbent seem promising for P removal from urban wastewater compared with other low-cost adsorbents.