Nitrification Performance of a Submerged Biofilter in a Laboratory Scale Size of the Recirculating Shrimp System

Abstract

A submerged biofilter (SBF) with 0.1 m(3) of filter medium was maintained without backwash at four different water temperatures (14 degrees C, 18 degrees C, 22 degrees C and 26 degrees C) in four different recirculating systems stocked with green tiger shrimp (Penacus semisulcatus). The ammonia removal profile and nitrification performance of the SBF was evaluated at feed loading rates of 2.65 g day(-1) at 14 degrees C, 5.52 g day(-1) at 18 degrees C, 7.91 g day(-1) at 22 degrees C and 10.94 g day(-1) at 26 degrees C In all of the experimental systems, the ammonia removal rate per unit volume of filter medium (the volumetric total ammonia nitrogen conversion rate, VTR) increased at the start of the experiment, reached and maintained a maximum value for a period of time, then decreased sharply. Statistical analysis revealed significant relationships among water temperature, total ammonia nitrogen (TAN) and the VTR. Temperature was not more important than TAN when comparing their effects on the VTR of the SBF.