Three-Dimensional Dual-Network Gel-Immobilized Mycelial Pellets: A Robust Bio-Carrier with Enhanced Shear Resistance and Biomass Retention for Sustainable Removal of SMX

Qingyu Zhang, Haijuan Guo, Jingyan Zhang and Fang Ma ()
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Qingyu Zhang: School of Environment, Harbin Institute of Technology, Harbin 150090, China
Haijuan Guo: College of Environment, Liaoning University, Shenyang 110036, China
Jingyan Zhang: School of Environment, Harbin Institute of Technology, Harbin 150090, China
Fang Ma: State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China

Sustainability, 2025, vol. 17, issue 19, 1-18

Abstract: Fungal mycelial pellets (MPs) exhibit high biomass-loading capacity; however, their application in wastewater treatment is constrained by structural fragility and the risk of environmental dispersion. To overcome these limitations, a dual-crosslinked polyvinyl alcohol–alginate gel (10% PVA, 2% sodium alginate) embedding strategy was developed and stabilized using 2% CaCl 2 and saturated boric acid. This encapsulation enhanced the tensile strength of MPs by 499% (310.4 vs. 62.1 kPa) and improved their settling velocity by 2.3-fold (1.12 vs. 0.49 cm/s), which was critical for stability under turbulent bioreactor conditions. Following encapsulation, the specific oxygen uptake rates (SOURs) of three fungal strains (F557, Y3, and F507) decreased by 30.3%, 54.8%, and 48.3%, respectively, while maintaining metabolic functionality. SEM revealed tight adhesion between the gel layer and both surface and internal hyphae, with the preservation of porous channels conducive to microbial colonization. In sequential-batch reactors treating sulfamethoxazole (SMX)-contaminated wastewater, gel-encapsulated MPs combined with acclimated sludge consistently achieved 72–75% SMX removal efficiency over six cycles, outperforming uncoated MPs (efficiency decreased from 81.2% to 58.7%) and pure gel–sludge composites (34–39%). The gel coating inhibited hyphal dispersion by over 90% and resisted mechanical disintegration under 24 h agitation. This approach offers a scalable and environmentally sustainable means of enhancing MPs’ operational stability in continuous-flow systems while mitigating fungal dissemination risks.

Keywords: mycelial pellets; bio-carrier stabilization; PVA–alginate crosslinking; immobilized microbial technology; sulfamethoxazole degradation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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