Effect of microwave on biomass growth and oxygen production of microalgae Chlorella pyrenoidosa cultured in real wastewater

The oxygen production efficiency of microalgae is a critical factor for the performance of algal-bacterial symbiotic systems during real wastewater treatment. This study proposed a new method to enhance the growth and oxygen production rate of microalgae via microwave irradiation. The oxygen production performance of Chlorella pyrenoidosa grown in real wastewater was evaluated in the presence of microwaves, and the photosynthetic oxygen production rate was calculated based on the produced chlorophyll-a and dissolved oxygen. The results showed that microwave treatment promoted both algal growth and oxygen production. Chlorella pyrenoidosa was irradiated by microwave during the logarithmic phase. When the radiation power was 400 W and the treatment time was 25 s, the oxygen production of Chlorella pyrenoidosa and chlorophyll-a increased by 10.7% and 12.4%, while the photosynthetic oxygen production rate increased by 5.8%. Therefore, microwave can save the aeration energy required for degrading organic matter in real wastewater by algal-bacterial systems.