Israeli researchers test anaerobic slurry module for solids digestion and denitrification in zero discharge marine fish culture

摘要

Recirculating aquaculture systems use biofilters where nitrifying bacteria convert toxic ammonia to nearly harmless nitrate. Waste nutrient-rich water and sludge are often dumped, or drained to a holding pond and spread over fields. However mariculture water and sludge are salty and can't be so dumped. Zero discharge technology can resolve this. It adds to the conventional recirculating system a second, anaerobic biofilter, where denitrifying bacteria convert nitrate into nitrogen gas. This dual-biofilter (nitrifying-denitrifying) system greatly reduces the dependence on water exchange. It also eliminates most of the organic solids and captures nearly all phosphate in the sludge. The low quantity of disposed saltwater and sludge makes the dual-looptechnology attractive for mariculture recirculating farms.