Optimizing rapid biofloc establishment: Effects of inoculum biofloc concentration and feed addition on maturation time, water quality, and nutritional composition

Abstract

Despite growing interest in biofloc technology, methods for rapid biofloc system establishment remain unclear. While mature biofloc inoculation can accelerate system maturation, the critical parameters of inoculation biofloc total suspended solids (TSS) and feed addition amount remain underexplored. This study addressed this gap through two trials. Trial Ⅰ tested initial biofloc TSS levels (100, 200, and 300 mg/L). While the 300 mg/L treatment accelerated biofloc maturation, statistical analysis revealed no significant differences (p > 0.05) in TSS production, total ammonia nitrogen (TAN) removal efficiency, or nutritional profiles (crude protein/fatty acid content) between the 200 and 300 mg/L treatments. Consequently, 200 mg/L TSS was identified as the optimal inoculum concentration. Trial II evaluated feed addition amount (0.5–5.0 g/L) using the 200 mg/L biofloc inoculum. Results showed that higher feed addition amount significantly prolonged maturation time (p < 0.05). While the 0.5 and 2.0 g/L groups had comparable nutritional quality, the 2.0 g/L group exhibited superior TAN removal rate and significantly lower peak nitrite concentration (p < 0.05). These results demonstrate that 2.0 g/L feed supplementation balances nutritional value with enhanced water treatment capacity. Our results indicate that an inoculated biofloc TSS of 200 mg/L combined with a feed addition of 2.0 g/L is an appropriate biofloc expansion strategy. This study optimizes the accelerated cultivation process of biofloc, offering valuable insights to facilitate its large-scale implementation.