Fungal pretreatment as a promising approach for simultaneous recovery of phosphorus and carbon resource from garden waste: Performance and mechanism

Abstract

Garden waste (GW), which is rich in organic matter and nutrients such as nitrogen (N) and phosphorus (P), has not been fully utilized for resource recovery. This study investigates a novel approach to recover both P and carbon source from GW by fungal pretreatment. Four types of GW—Zoysia matrella (L.) Merr (ZMM), Lolium perenne L (LPL), Platanus × acerifolia (Aiton) Willd (PAW), and Cinnamomum camphora (L.) Presl (CCP)—were subjected to alkaline, thermal, and fungal pretreatments. Results showed that fungal pretreatment was more effective than alkaline and thermal methods, especially for turfgrass GW. After 7 days of fungal pretreatment, the orthophosphate (PO₄-P) concentration in the LPL supernatant was 2.15 times that of the control. Enzyme activity and metagenomic data revealed higher abundances of lignin degrading enzymes in turfgrass GW, with laccase being the dominant enzyme. Fungi convert organic phosphorus into PO₄-P by secreting 3-phytase. Ammonium was also produced during fungal pretreatment, resulting in a weakly alkaline supernatant that promoted the precipitation of P as struvite. Consequently, a 43.51 % recovery of P from LPL as struvite with 91.3 % purity was achieved. The residual leachate served as a carbon source, achieving 78.67 % nitrate removal and 76.48 % total nitrogen removal. This study proposes a sustainable strategy for simultaneous P and carbon recovery from GW.