abstract
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 FTIR-ATR 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 degrees C for 60 min. The Langmuir isotherms describe the experimental data with a maximum adsorption capacity of 4.57 mg P/g at 25 degrees C. The adsorption process reached equilibrium within 120 min for different dosages (5, 10, and 20 g/L at 25 degrees 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 degrees 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.
keywords
HEAVY-METALS; PHOSPHATE; EGGSHELL; RECOVERY
subject category
Environmental Sciences & Ecology
authors
Santos, AF; Lopes, D; Alvarenga, P; Gando-Ferreira, LM; Quina, MJ
our authors
Daniela Vanessa Rosendo Lopes
Junior ResearcherProjects
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
Andreia F. Santos acknowledges the Fundacao para a Ciencia e Tecnologia (FCT) for the Ph.D. Grant (2020.08213. BD) . Andreia F. Santos, Licinio M. Gando-Ferreira, and Margarida J. Quina acknowledge the support of CIEPQPF (UIDB/00102/2020) , financed by FCT through national funds. P. Alvarenga acknowledges the support of LEAF-Linking Landscape, Environment, Agriculture And Food Research Centre (Ref. UIDB/04129/2020 and UIDP/04129/2020) , and Associated Laboratory TERRA. Daniela V. Lopes acknowledges the support of CENTRO- 01-0247-FEDER-181254 project in the frame of CENTRO 2020, and CICECO - Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC) .