Effect of treated sewage on growth of marine algae

Abstract

Eight algal species belonging to Chlorophyta, Rhodophyta and Phaeophyta were used to assess the effect of different concentrations of secondary treated sewage on their growth. Chlorophyta and Rhodophyta members. <i>Ulva fasciata</i> and <i>Gracilaria verrucosa</i> respectively, showed good growth as compared to the control in 5% sewage-seawater medium. Phaeophyta members did not show satisfactory growth. However, in 5 and 10% sewage-seawater media growth was observed in <i>Padina tetrastromatica, stoechospermum marginatum</i> and <i>Spatoglossum asperum</i>, while <i>Sargassum</i> sp. was found to be least tolerant to sewage pollution. Correlation coefficients between algal growth (weight) and nutrients showed that <i>U. fasciata</i> and <i>G. verrucosa</i> can be cultivated in diluted sewage effluent as tertiary sewage treatment species to remove nutrients in high concentrations and toxic substances from the sewage polluted areas.