Evaluation of the effects of aeration cycle and culture medium concentration on biomass qualitative and quantitative indices in microalga Spirulina as candidate for wastewater treatment

Microalgal culture can be a combination of three environmental factors, treatment of wastewaters, production of renewable energy resources for replacement of fossil fuels and reduction of the greenhouse gas emissions. Microalga Spirulina is not just a good candidate forwastewater treatment (due to the ability toremove ofnitrogen andphosphorus), but also it plays a roleinreduction of greenhouse gas emissions because of the consumption of atmospheric CO2. Severalfactorscontributetothegrowth of thisspecies. In this study, the influence oftwo factors, aerationcycle(15 minutes to 12hours) andZarroukmediumconcentration(20-100%), on quantitative(specific growth rateanddry weight) and qualitative indices(chlorophyll andPhycobiliproteinscontent) of this species has been evaluated by usingRSM-CCDmethod. The results indicatedthat increase in frequency ofaerationand the concentration ofthe medium can enhance the specificgrowth rateand also the dry weight. The highestchlorophyll content was obtained in median values of bothfactors. According to phycobiliproteins, the effect of the medium concentration on these pigments is the same as the effects on chlorophyll, but the influence of aerationcycle is completely vice versa. It seems that aeration cycle has an important role on quantitative and qualitative indices of biomass, although it is not well studied yet. This factor can partially offset the negative effects of the culture medium dilution and reduce the costs of total processes.