Previously to its use as culturing medium for algae, we have studied the various characteristics of the sewage extracted from marine fish rearing ponds, through a purificating system called "foamer". Qualitatively, this sewage differs from the sea water which produced it on various points : It is richer than the water in Organic Carbon, Organic Nitrogen, Ammonia, particulate matters, phosphorus and varied metals. However the concentration factors are not constant and they change in time. This sewage is toxic for some group of animals and this toxicity varies with the concentration but also the age of the product. Finally, it is eutrophicant and this richness enables to the growth of algae for long periods but the boundary between toxicity and eutrophy Is... |