The Israeli Journal of Aquaculture - Bamidgeh 55(4), 2003
The 7th Annual Dan Popper Symposium


Daniel Conijeski¹*, Noam Mozes¹ and Israel Haddas²

1 Israel Oceanographic and Limnological Research Ltd., National Center for Mariculture, P.O.Box 1212, Eilat 88112, Israel

2 Kora (1980) Architect Engineers Consultants Ltd., P.O.Box 38, Zofit 44925, Israel


Expansion of the aquaculture industry in Israel has been constrained by increasing water shortages and environmental restrictions. Today, prospects for enhancing local fish production rely on the implementation of recirculating aquaculture systems (RAS). Although recirculating fish farms are on the rise in Europe, the USA and Israel, RAS projects remain challenged by economic performance. Recently in Israel a "low-head" RAS was developed. The system proved more compatible to local conditions and has already made vast improvements towards economical goals. The recent introduction of an innovative system, Mega-Flow ®, will further extend the economic feasibility of intensive fish production in land-based RAS. Mega-Flow® is a patent-pending technology developed by Kora Ltd. in cooperation with the National Center for Mariculture (NCM). The low-head system, combined with the Mega-Flow® technique, enables an intensive RAS to be driven by only one air-blower. The Mega-Flow® system is based on state-of-the-art advanced design airlifts. The system includes two water circuits: (1) the main loop, where pond water is pumped through airlift pumps several times per hour creating a massive water flow (hence the name "Mega-Flow"). This loop fills three functions: aeration, CO2 stripping and the scouring of settled wastes and uneaten feed from the system. (2) The second loop is performed by smaller airlifts that circulate the water once or twice an hour through an up-flow non-pressurized filter for suspended solid removal and a moving bed biofilter for nitrification. In both filters, a "macaroni" type plastic substrate was used. The remarkable advantages of the low-head Mega-Flow® system are the simplicity and reliability of its water treatment components, the major reduction in the mechanical and electrical infrastructures and the lower risk of system failure. These advantages result in a considerable reduction of fish production costs by eliminating the use of expensive pure oxygen, increasing energy efficiency and lowering initial capital, operational and maintenance costs. The presentation will show performance results of intensive sea bream culture in two Mega-Flow® pilot systems, one at the NCM, Eilat, and the other at Gan Shmuel near Hadera.