Floating faeces: Effects on solid removal and particle size distribution in RAS

The cork treatment led to a substantially higher solid load being delivered to the drum filter via the wastewater outflow than in the control system. The average removal efficiency of cork-treated wastes was more than twice that achieved in the control system (59% vs. 25%). Total suspended solid (TSS) in the backwash stream of the drum filter was about five times greater in the cork diet treatment. There was no significant difference in the particle size distribution or TSS load of water passing the 100 μm gauze of the drum filter in the two systems. Cork supplementation did not affect growth or mortality of rainbow trout. The present study shows that the application of floating faeces is an exciting prospect in recirculating aquaculture systems, offering significant improvements in solid removal efficiency.