EVALUATING THE DILUTION OF MUNICIPAL WASTEWATER ON BIOMASS INCREASE, LIPID PRODUCTION AND NUTRIENT REMOVAL BY THE BLUE-GREEN ALGAE Spirulina platensis (Geitler)

Wastewater generated daily in urban localities could provide nourishment to algae for potential production of biofuel and biochemicals. This study presents an integrated approach to the use of Spirulina platensis cultures for the treatment of domestic wastewater and lipid extraction. In this experimental approach, wastewater subjected only to the primary settling process was used as nutrient media at different concentrations of 100%, 75%, 50%, and 25% wastewater diluted with distilled water, and Spirulina platensis was cultured in these mediums for 20 days. The inoculated medium was incubated at 30 degrees C in the presence of light (42 mu mol photon m(-2).s(-1)) by using light/dark cycle of 12 hours. S. platensis consumed nitrite, nitrate, phosphate and ammonium from wastewater, and it increased its biomass and its lipid amount. Although the highest biomass increase was observed at the wastewater medium without dilution (100% wastewater) (the control group was not included), the highest lipid production was found in 25% wastewater. On the other hand, the percent reduction in the level of nitrite, nitrate, phosphate and ammonium in 75% wastewater medium was 91%, 99%, 99% and 99%, respectively. Despite the low lipid content, since Spirulina platensis can live in harsh conditions and increase its biomass rapidly, they can be easily cultivated in wastewater. Therefore, their use in wastewater for biodiesel production was found appropriate. The resulting algae biomass after oil extraction can be also used in different industrial sectors.