BIOFILTER START-UP METHODS IN CLOSED RECIRCULATING SEAWATER SYSTEMS.

摘要

Spontaneous formation of the active layer in biological filters for removal of ammonium and nitrites from cold seawater usually takes a few months. The reduction of warm-up period (time required for a biofilter to reach full operation) is one of the principal problem in aquaculture. Fish excrete ammonia and lesser amounts of urea into the water as wastes. Two forms of ammonia occur in aquaculture systems, ionized and un-ionized. The un-ionized form of ammonia (NH_3) is extremely toxic while the ionized form (NH_4~+) is not. Both forms are grouped together as "total ammonia". Through biological process, which has two phases, toxic ammonia can be degraded to harmless nitrates. Inoculation of the new filters with well-established filter material underthe low water temperature usually happens on 75-80th day. The goal of the research was to analyze the hydrochemistry dynamics in recirculating artificial seawater systems (CRWS) in order to stimulate the biofilter start-up procedure.