Water Quality Impacts of Three Biofilter Designs in Recirculating Aquaculture Systems

Abstract

ABSlRACTNine recirculating aquaculture systems utilizing three biofilter types were placed on line and stocked with yellow perch, Percaflavescens, fingerlings. Biofilter type differed among systems, and included upflow pulsed bed bead filter, packed tower trickling filter, and rotating biological contactor. Following filter acclimation, a comparative analysis of biofilter performance was conducted, involving measurement of temperature, pH, dissolved oxygen, total ammonia-nitrogen, nitrite nitrogen, nitrate-nitrogen, alkalinity, total hardness, carbonaceous biochemical oxygen demand, dissolved organic carbon, and total suspended solids. Filter bed emergence promoted effective carbon dioxide stripping, pH maintenance, and consistent nitrification performance in trickling filters and rotating biological contactors. Higher total ammonia nitrogen mass removal rates were observed in trickling and rotating biological contactor filters than in bead filters. Low total ammonia nitrogen mass removal rates and nitrification efficiencies for all filters resulted from relatively high carbonaceous biological oxygen demand loadings. Analysis of areas under mass removal curves showed that RBC filters were surface area limited. Foam formation in trickling filters effectively removed total suspended solids from the culture water. Filter type did not have a significant effect on median

Effect of four different pretreatments in nitrogen and phosphorus flow and mass balance in effluents of a recirculating aquaculture system.

“…Recirculating aquaculture systems (RAS) are an alternative to traditional flow through aquaculture production systems (pond or raceway) due to economical, hydrological and environmental constraints. These systems have been characterized by low water consumption, strict control of water quality and effective solid removal efficiency (Timmons et al, 2001;Hall et al, 2002;Mirzoyan et al, 2010). Two of the most important aspects involved in the operation of a RAS are water quality control and total suspended solid management, first within the system and later as effluent disposal.…”