Nutrient assimilation and growth of some seaweeds in mixtures of sea water and secondary sewage treatment effluents

Abstract

Preliminary experiments with several economically important seaweeds studied their utilization of the major inorganic nutrients contained in secondary sewage effluent. Optimal growth occurred in a sewage—sea-water mixture upon addition of trace elements. Growth was similar whether nitrogen was mainly in the form of ammonia or nitrate. The assimilation of nitrogen and phosphorus was in a ratio, by atoms, which was considerably higher than that commonly found for phytoplankton. Phosphorus remained after nitrogen had been depleted from the medium. Methods for the restriction of both phytoplankton blooms and the growth of epiphytic algal species in large continuous flow cultures are discussed.