Raw Oyster Shells as Carrier for Nitrifying Biofilm in Aerated Biofilter

Oyster shells wastes resulting from the mariculture presents an imperative disposal problem in the coastal region. In this study, the nitrification efficiency on an aerated biofilter with raw oyster shells (ROS) as the sole buffer agent and the biomass carrier was evaluated. The capability of alkalinity supplied by ROS was found to be about 1050 mg/L, enabling a loading ammonia concentration up to 147 mg/L being removed. A substantial NH₄⁺-N removal of 65% could be achieved even at the loading concentration as high as 240 mg·L^-1. About 100% nitrification was maintained as the influent NH₄⁺-N concentration kept below 120 mg/L. The nitrification kinetics of biofilm with ROS fit well to Monod kinetics equation. The saturation constant K_m was 625 mg/L for the nitrifier with ROS, about one order of magnitude higher than that for compared plastic ball (PLB) carrier system.