Comparative phycoremediation of sewage water by various species of algae

In this study sewage water treatment efficiency of chlorella vulgaris,rhizoclonium hieroglyphicum and mixed algae culture (microspora sp.,navicula sp.,lyngbya sp.,cladophora sp.,spirogyra sp. and rhizoclonium sp.) was compared. sampled wastewater was analyzed for various parameters (i.e.,cod,bod,ts,tss,tds,tc,fc,tkn,tp,no3-n,po4,so4 and cl-) and concentrations of all these parameters in the untreated water were above the permissible limits of national environmental quality standards of pakistan (2000). various algal species were used to treat sewage water by varying pond size,treatment duration,seasonal variation and growth rate of algae to arrive at the optimum outcome. maximum percent reductions of various parameters,attained with c. vulgaris,were: chemical oxygen demand (98.3%),biochemical oxygen demand (98.7%),total kjeldahl nitrogen (93.1%),total phosphorus (98.0%),nitrate (98.3%),phosphate (98.6%),chloride (94.2%),total coliforms (99.0%),faecal coliforms (99.0%) and total dissolved solids (98.2%) while maximum reduction in total suspended solids (92.0%) was obtained with a mixed algae culture and maximum increase in biomass by r. hieroglyphicum (0.75 g l-1 day-1). reduction in the concentration of pollutants in sewage water was to such a low level that it can be thrown in waterbodies without any further treatment. © pakistan academy of sciences.