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[Display omitted] • The presence of MPs shortened the granulation time. • MPs acted as the inducible nucleus to accelerate sludge granulation. • MPs addition enhanced non-Newtonian flow characteristics of sludge. • MPs addition improved the removal efficiency of pollutant. • The formed AGS by applying MPs had a four-layer structure. This study provides a sustainable manner for direct cultivation of aerobic granular sludge (AGS) by addition of mycelial pellets (MPs) into continuous-flow aerobic MBR. The results showed that the granulation time in MPs-MBR was shortened by at least 65 days, accounting for enhanced mean size of granules (0.68–0.76 mm), increased mixed liquor suspended solids (MLSS) concentration (12.8 g/L) and improved settling ability (78.1 mL/g), in comparison with that of 0.23–0.28 mm, 9.8 g/L and 102.1 mL/g in control MBR. MPs-MBR demonstrated significant advantages in terms of COD reduction (97.0–99.1%), NH 4 +-N reduction (100%) and TN reduction (32.27–42.33%). MPs, extracellular polymeric substances (EPS) and filamentous bacteria acted as inducible nucleus, crosslinking matter and supporting skeleton, respectively, in favor of promoting the formation and stabilization of AGS with a four-layered structure. The relevant mechanism was underlined by rheological analysis, indicating that MPs addition enhanced non-Newtonian flow characteristics and network structure of sludge. [ABSTRACT FROM AUTHOR]

In this study, mycelial pellets (MPs) were employed as efficient and sustainable bio-carriers to alleviate membrane fouling in membrane bioreactor (MBR). The comparative study was performed in lab-scale MBR in the absence and presence of MPs addition under continuous operation for 80 days. The results demonstrated efficient removal of chemical oxygen demand (COD) and ammonia nitrogen (NH 4 +-N) for both systems, while MPs addition led to lower rate at which transmembrane-pressure was increased, lower filtration resistance, thinner bio-cakes and fewer contents of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in bio-cakes of membrane surface. Adding MPs into MBR could enhance biomass retention and EPS content in suspended liquid, thus accelerating the granulation of activated sludge, which should be responsible for mitigation of membrane fouling. According to the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the total surface free energy between membrane and foulants was always attractive, but total interfacial interaction especially acid-based (AB) interaction in the presence of MPs was weaker than that in the absence, confirming lower adhesion force induced by MPs. Furthermore, high throughput sequencing analysis of bio-cakes illustrated that a smaller relative abundance of EPS producer including the classes Gammaproteobacteria , Alphaproteobacteria and Actinobacteria , and a higher abundance of SMP decomposer including the class Chloroflexia were observed. The relevant mechanisms were underlined schematically to explain the function of MPs in mitigating membrane fouling process, which could be attributed to formation of biofilm with MPs serving as bio-carriers followed by promoted sludge granulation. This study provides a proof-in-concept demonstration of using MPs as bio-carriers to mitigate membrane fouling, making wastewater treatment by MBR more efficient, more reliable and more sustainable. [Display omitted] •MPs were employed as efficient bio-carriers to alleviate membrane fouling. •The presence of MPs promoted sludge granulation. •MPs addition reduced the deposition of flocs sludge on membrane surface. •MPs addition led to lower filtration resistance and fewer foulants. [ABSTRACT FROM AUTHOR]