Green synthesized MgO combined with dielectric barrier discharge plasma enhanced phosphorus (P) recovery from livestock wastewater: a dual approach for management of wastewater and P resources

Phosphorus (P) recovery from wastewater using integrated techniques i.e., adsorption combined with advanced oxidation technologies is a novel approach for cleaning wastewater and preventing eutrophication. This approach, however, has not been extensively studied, particularly in the context of real wastewater applications. In this study, a green biomass-based sol-gel method was developed using potato starch (PS) and MgCl ₂·6H ₂O to synthesize MgO (PS-MgO). The unique synthesis method resulted in PS-MgO composed predominantly of spherical particles with an average size of about 103 nm and exhibited superior P adsorption performance compared to commercial MgO materials (GH-MgO and AD-MgO). The Langmuir maximum P adsorption capacity (mg/g) of the PS-MgO was 429.4, while that of the commercial GH-MgO and AD-MgO was 341.3 and 421.7, respectively, at the solution pH 7.0. The kinetic model fitting demonstrated that the adsorption rate of PS-MgO was faster than the two commercial MgOs. Importantly, PS-MgO can maintain a high P adsorption capacity across a wide pH range (425 mg/g at pH 5.0 and 369 mg/g at pH 11.0), whereas the P adsorption capacities of GH-MgO (153 at pH 5.0 and 297 at pH 11.0) and AD-MgO (422 at pH 5.0 and 200 at pH 11.0) were more pH-dependent. In addition, PS-MgO exhibits high selectivity for P capture in solutions containing coexisting ions, and the P-loaded PS-MgO can efficiently release P through acid or base treatment, highlighting its potential for reuse as a fertilizer. To enhance P recovery from real livestock wastewater, the dielectric barrier discharge (DBD) plasma technology was combined with MgO adsorption. The P recovery capacity of MgOs from livestock wastewater increased 1.4–1.7 times after DBD plasma treatment, attributed to the degradation of aromatic proteins and microbial metabolites. These findings provide new insights into the design of efficient and environmentally friendly materials for P recovery, while also demonstrating the potential of integrating advanced oxidation technologies with adsorption processes.