Nitrogen and phosphorus balance in continuous culture of rotifer Brachionus plicatilis sp. complex using recirculating and flow through systems

Abstract

We conducted continuous culture of the rotifer Brachionus plicatilis sp. complex using recirculating and flow through systems for 24 days. Input, output and accumulation of nitrogen (N) and phosphorus (P) in these systems were examined. Most of N and P input were supplied from the diet in both systems (over 96%). On the basis of the total input, output of N and P from the recirculating system and the accumulation of N and P in the system were 57.2, 55.1, 37.5 and 53.2%, respectively. In the flow through system, much of N (87.8%) and P (91.2%) were outputted, and accumulation of N (5.2%) and P (7.6%) were minimal. We compared each item in the recirculating system. Output of N and P were higher from the culture tank using the mat filter material. Values of N and P accumulated in the filter materials in the biofilter tanks were higher than the wastewater from the foam fractionator. Accumulation in the culture water was not only nitrate-nitrogen but also total ammonia-nitrogen. From these results we propose improvements of the recirculating system with respect to extension of the mat or foam fractionator, and introduction of floating filter material into the culture tank.