Separation Performance of a Low-pressure Hydrocyclone for Suspended Solids in a Recirculating Aquaculture System

Abstract

The separation performance of a low-pressure hydrocyclone (LPH) was evaluated for suspendedsolids removal in a recirculating aquaculture system (RAS). The dimensions of the LPH were 335 mm cylinder diameter, 575 mm cylinder height, 60 mm overflow diameter, 50 mm underflow diameter, and 68° cone angle. The inflow rate varied (400, 600, 800, and 1,000 mL s -1 ) with 25%, 25%, 20%, and 10% of bypass (R f ), respectively. The maximum total separation efficiency (Et) and reduced separation efficiency (E't) for suspended solids from the effluent of the second settlement tank (before biofiltration) were 58.9% and 45.2%, respectively, at an inflow rate of 600 mL s -1 and 25% of R f . The maximum Et and E't for suspended solids from the water supply channel (after biofiltration) were 24.4% and 16%, respectively, at an inflow rate of 1,000 mL s -1 and 10% of R f . The maximum grade efficiency (Ei) was 51.6% for a 300 µm particle size at an inflow rate of 600 mL s -1 with 23% of R f . The maximum reduced grade efficiency (E'i) was 37.6% for a 300 µm particle size at an inflow rate of 1,000 mL s -1 with 11% of R f . The results indicate that the separation performance of the LPH for suspended solids removal was size selective and that maximum removal occurred at particle sizes ranging from 300 to 500 µm.

A review on the research status and development trend of equipment in water treatment processes of recirculating aquaculture systems

“…When using a commercial LPH, various feed particles exhibiting different physical properties could be used to test the separation performance. Lee () found that the separation performance of LPH for suspended solids removal was selective, with the maximum particle size removed being 300–500 μm in diameter in a RAS. Then, Lee () tested the separation performance of an LPH with a lower inlet pressure (average 1.38–5.56 kPa) and using fine organic particles from 1 to 700 μm in diameter, and used the response surface method model to predict an optimum operating inflow rate of 30% and underflow ratio of 721 mL s −1 for the LPH at maximum total separation efficiency.…”

Review of waste phosphorus from aquaculture: Source, removal and recovery

“…The solid waste from RASs, which includes faeces, uneaten food and detached bacterial film, contains TP ranging from 0.2% to 12%. 138,139 A typical RAS removes 65-96% of P through the effective removal of solid waste. 136 TP in the backwash waters of drum-filters of RASs ranges from 12.5 to 85.6 mg P /L (Table 5), and the dissolved P accumulates at levels as high as 7-67 mg P/L.…”

Performance investigation of a novel design of vertical micro-screen drum filter for a recirculating aquaculture system (RAS)

“…Compared to other forms of aquaculture production, RAS reduces the potential environmental impacts such as eutrophication and water dependence (d 'Orbcastel et al 2009). Solid wastes in the RAS usually originate from feeds that are composed of organic matter with a low density and wide range of particle sizes (Lee 2010). The solid organic wastes from uneaten feed and fish feces can reach up to 23% of the total feed supplied and can have a large effect on total solids production (Lee et al 2009).…”