Studies on the reduction of environmentall road in the waste water from rotifer culture by the introduction of Chemostat System

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Waste waters from hatcheries are out of control in the eye of the law at present. "Zero-emission" should be imposed, however, from the view point of "Exist together Ecosystems" in the near future. In this program, we discussed advantages of "Chemostat-rotifer-production-system, the newest invention" after precision experiments on "nitrogen (N) conversion efficiency from food provision to rotifer", "material flow" and "rotifer quality" in comparison with Batch-culture-system, the typical ordinary production system.In Batch-culture-system, increasing unionized-ammonia affected and lowered the food conversion efficiency in both L and S type rotifers, which induced an outbreak of unassimilated food in water. As a result, the concentration of organic substances was high compared by the amount of harvested rotifers.In Chemostat system, production efficiency (rotifer N divided by assimilated food N) was examined. The maximum value in L-type rotifer was 40% that was higher than the 30% in S-type rotifer. Collectively, ammonia emission from Chemostat system was lower than that from Batch-culture-system, and it was less than quarter of Batch-culture-system.As an index of the activity of harvested rotifers, carbon and nitrogen contents were evaluated. Those from Batch-culture-system were far less than the ones from Chemostat system, which may because of the worsening environmental conditions in Batch-culture as time elapsed.