A comparative study on growth characters and nutrients removal from wastewater by two microalgae under optimized light regimes

Microalgae have displayed great potential in wastewater treatment with simultaneous biomass production and nutrient removal. However, the characteristics of growth, nutrient removal varied greatly among microalgal species and also affected by light regimes. In this study, two microalgae Spirulina platensis (S.p.) and Scenedesmus obliquus (S.o.), belonging to cyanobacteria and green algae, were cultivated under the optimized light regimes respectively to investigate the biomass yield, biochemical components, nutrients removal and recovery from domestic wastewater. The results showed that based on the response surface methodology (RSM), the microalga S.o. preferred higher light intensity and daily illumination time than the S.p. and the models could predict the two microalgal biomass yields well respectively. Under the optimized light regimes, the microalga S.o. showed better growth in domestic wastewater with higher chlorophyll and lipid content than the S.p., while the microalga S.p. was rich in proteins and carbohydrates. The two microalgae both showed efficient nutrients removal from the domestic wastewater, but the microalga S.o. had higher nutrients recovery efficiencies than the S.p. despite for relatively lower TN removal. This study could provide sufficient information for applying the two microalgae in domestic wastewater treatment with simultaneous biomass production and nutrients recovery.