The performance, mechanisms, and effects of various coexisting ions on phosphorus (P) adsorptive capture in biogas slurry using MgO-doped biochar (MBC) were investigated. The results revealed that in comparison to the pristine biochar, the introduction of MgO significantly improved the P adsorptive capture feasibility of MBC. In addition, the process of P capture by MBC was not affected by the initial pH of the solution. The process of P capture could reach equilibrium within 120 min and be simulated using both the pseudo-first-order and the pseudo-second-order kinetic models. In addition, the highest P capture capacity calculated from the Langmuir isotherm model was approximately 129.35 mg/g. The coexisting of cations including NH4+, Ca2+, Cu2+, Cd2+, Pb2+, Zn2+, and Cr3+ in higher concentrations of promoted P adsorptive capture through precipitation and ionic atmosphere effects. The presence of coexisting ions including SO42-, HCO3-, and fulvic acid (FA) had a certain inhibitory effect on the P adsorptive capture through competitive adsorption with phosphate. The existence of monovalent ions such as K+, Na+, Cl-, and NO3- had no significant effect on P adsorptive capture. The adsorptive capture of P by MBC was affected by various processes including electrostatic attraction and surface complexation, and the presence of different coexisting substances had different impacts on the P adsorption. Adding to these, the P in the biogas slurry was completely adsorbed by the MBC during the experiment, indicating that MBC is a promising composite in the engineering application for the capture of P from wastewater.
Keywords: Adsorption; Biogas slurry; Coexisting ions; Engineered biochar; MgO; Phosphate.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.