Algal Turf Scrubber
Hi all,
As SmithRC suggests algal turf scrubbers are mainly used in marine systems, the reason they don't tend to be used so much in freshwater aquariums/aquaculture is purely that vascular plants combine a high potential growth rate with ease of harvesting, but an algal scrubber will definitely work.
The aquaculture/waste water treatment equivalent is using Reeds (Phragmites), Water Hyacinth (Eichornia) etc.
I never tested the nitrates when I was using the planted trickle filters (basically over tank plastic guttering filled with hydroleca granules, plants planted in rockwool and the water flowing over weir back into the tank), but the combination of access to atmospheric O2 and CO2, wet and dry filtration, microbial mat and vascular plant growth gives both highly oxygenated water and absolutely huge biological filtration potential. They were also very low maintenance.
cheers Darrel
I've put the abstract of a relevant paper below, please PM me if you want the full paper.
Journal of Environmental Management (1997) 50, 283–299
The Treatment of Aquaculture Wastewaters—A Botanical Approach
T Redding, S Todd and A Midlen
University of Hull International Fisheries Institute, Hull, HU6 7RX, U.K
Abstract
The wastewater from freshwater fish farming is responsible for nutrient enrichment in receiving waters. This frequently causes localised problems for the management of the freshwater environment. Conventional wastewater treatment systems are costly to install and operate. This paper investigates the potential of an alternative system. Untreated wastewater from a recirculation system used to culture fish was passed through three treatment systems containing different species of aquatic macrophyte:Rorippa nasturtium-aquaticum(the emergent system);Azolla filiculoides(Lam) (the free floating system); and,Elodea nuttallii(Planch.) (the submersed system). Concentrations of ammonia-N, nitrate-N and phosphorus in all three systems was significantly reduced compared to untreated wastewater during both weekly and twenty four hour sampling regimes. The role played by microbial and bacterial populations in comparison to direct uptake by plants is discussed, as are the implications for system design. The importance of plant cropping, especially in the emergent system, is highlighted as is the potential for use of such a system in environmental management.
