Unraveling the microbial and functional mechanisms driving rapid algal-bacterial granular sludge formation in mariculture wastewater.
AI summary
75% confidenceThis MEC study investigates Algal-bacterial granular sludge, Granulation, Mariculture wastewater. The research focuses on system optimization and characterization.
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Abstract
Algal-bacterial granular sludge (ABGS) has unique advantages and broad application prospects in the treatment of mariculture wastewater. However, the rapid granulation process and performance evolution of ABGS under high salt stress have not been clearly defined. Compared with AGS, the influence of algal intervention on the structural integrity and metabolic activity of particles under the same salinity gradient is also unknown. Therefore, in this study, a parallel ABGS and AGS system was established. The results showed that intertwined algal filaments provided a structural skeleton for particle formation and led to complete granulation of ABGS within 20 days. Compared with conventional AGS, ABGS formed under high-salinity conditions exhibited a larger average particle size (1.07 mm), higher biomass (7.59 g/L) and higher extracellular polymeric substance (EPS) secretion (258.56 mg/g VSS). Additionally, chemical oxygen demand (COD) and total inorganic nitrogen (TIN) removal efficiencies exceeded 99% and 66%, respectively. Metagenomic analysis revealed that Thauera, Fragilaria and Nitzschia were dominant taxa associated with granule formation and stabilization. ABGS also showed an elevated abundance of functional genes associated with nitrogen metabolism (nxrA, nasA, and nasD) and polysaccharide metabolism (glmM, glmU, and pmm-pgm), which were in accordance with the enhanced nitrogen removal and granulation capability. Increased abundance of tricarboxylic acid cycle genes further indicated the superior granulation performance of ABGS. Overall, this study clarifies the morphological evolution and microbial functional mechanisms underlying rapid ABGS formation in mariculture wastewater, offering valuable insights for engineering optimisation and application of this technology in saline wastewater treatment.