Ammonia-nitrogen uptake by sterile Ulva sp. was studied for the control of culture
pond water of intensive shrimp farming. The uptake rates were measured by batch and
semi-continuous operations, and analyzed with the Michaelis-Menten model of uncompetitive
inhibition. For the bateh uptake operations, the Michaelis-Menten parameters
were estimated, and the maximum rate and Michaelis constants were estimated as
3.4 X 10-2 kg kg-' h-' and 5.5 x lO-' kg m- respectively. The inhibitory factor increased
with the uptake time and with the decrease of the seaweed density. In the eases of
semi-eontiniious operations, the seaweed could continuously treat with the model farming
culture solution. Although the ratio of the seaweed density relative to the rate of
ammonia-nitrogen generation should be appropriately adjusted to keep lower inhibitory
factor in the seaweed, the ammonia-nitrogen concentration eould be maintained at a relatively
low level during operation. Then the ammonia-nitrogen uptake by the alga water
was roughly simulated and operation with moderate density of the algae in the pond
could maintain the ammonia-nitrogen concentration at a sufficiently low level in the
shrimp farming pond. The suggested treatment process might be attractive to control
pond water quality for intensive shrimp farming.