Introduction
Recirculating aquaculture systems (RAS) are closed-loop systems that reuse most of the water for fish production, with minimal exchange of new water. RAS have many advantages over traditional open systems, such as water conservation, land use efficiency, biosecurity, waste management, and environmental control. However, RAS also face many challenges, such as the accumulation of waste products, the maintenance of water quality, the prevention of disease outbreaks, and the high capital and operational costs.
This presentation address one of the key factors that affect the performance and sustainability of RA S - T he level of total suspended solids (TSS) in the water. TSS are the particles that are not dissolved in the water, and they can originate from various sources, such as fish feed, feces, biofilm, algae, and external inputs. TSS can have detrimental effects on fish welfare, the biochemical processes in biofilters , and growth rate of fish, the increased turbidity will also a ffect light regimes for maturation control.
Therefore, the removal of TSS is essential for the optimal operation of RAS.
The impact of particles for RAS
Particles represent the opportunity to remove the majority of the organic load in the water in RAS. Control of your particles will make the RAS stable and cost-effective.
The table fig. 1 show us the potential of effective particle removal in RAS as the leading factor for the water quality, having over 80% effect on the total P removal and up to 80% on the BOD5 removal. This is the key for balance reliable RAS.
Photo 1 and 2 i s from the same sturgeon farm on the same day, but photo 1is form a RAS loop with mechanical filtration for fast removal of the particle, photo 2 has sedimentation filtration for removal of the particles.
The approach for Particle Control
Drum filters, are the most common and cost-effective tool for particle removal in RAS , they can remove up to 90% of the particle-bound waste. The patented CM Aqua Beecell micro screen panel can lift and remove the particles gently without leaching back into the water.
Other technologies for fine particle control include intelligent control of drum filters(IC), protein skimmers, and submerged contact filters.
The factors that influence the particle control efficiency:
The size and shape of particles in RAS is the key for the cost-effective removal, allowing us to creat e the water for best fish welfare.
Discussion
The growth of RA S worldwide show a lot of innovation and seeking for best cost-effective solutions. Especially the salmonids farmed in RAS are in focus , as they have a high value and are well accepted by the consumers.
Does the design optimize for particle control sufficiently, considering the extreme impact is has?
Is common knowledge on particle control forgotten in the fast growth of the industry?
Reference:
Fig.1: Factors determining the size of suspended solids in a flow-through fish farm Alexander Brinker a,b,c, *, Roland Rosch a Fisheries Research Station of Baden-Wurttemberg, Untere Seestrasse 81, 88085 Langenargen, Germany b Limnological Institute, University of Constance, 78457 Konstanz, Germany c Institute for Lake Research of the Environmental Protection Agency Baden-Wurttemberg, Argenweg 50/1, 88085 Langenargen, Germany Received 14 May 2004; accepted 28 October 2004.