Fast granulation of flocculent activated sludge by mycelium pellet and wastewater biological treatment performance

Abstract

To investigate the universality of mycelium pellet (MP) assisted flocculent activated sludge (FAS) granulation, four different filamentous microbes (Aspergillus niger, Aspergillus fumigatus, Phanerochaete Chrysosporium and Streptomyces albicans) were used for bio-flocculation assisted activated sludge granulation, and the physicochemical properties and biological activity of aerobic granular sludge (AGS) with MP as skeleton were monitored. The results showed that inoculation of MP for an assisted flocculation strategy was better than filamentous spores. Spherical and rod-shaped microbes of FAS alternately adhered to different areas of the MP to form granular sludge with dense structure. Under the optimized conditions, the FAS biomass aggregated on four MPs reached 1.24–1.89 g/g, and the respiratory activity of corresponding MP-based AGS (MP-AGS) were 36.52–56.95 mgO2/gVSS of specific oxygen consumption rate. Compared to FAS, MP-AGS present better sedimentation performance (45–55 m/h of settling rate) and higher biological enzyme activity related to organic matter degradation and nitrogen conversion (49.82–60.37 mgTF/(gVSS∙h) of dehydrogenase, 0.26–0.42 mgNO2−-N/(min∙mg protein) of nitrate reductase). TN and TP removal efficiencies of MP-AGS were 9.96 %–19.59 % higher than those of FAS under high influent loads. This study confirmed the feasibility of mycelium pellet assisted flocculent activated sludge granulation using different microbes.