Study On The Improvement Of Oxygen Supply Efficiency Of Algae Cultivated In Municipal Wastewater By Microwave

Currently, energy crisis and environmental pollution are widely concerned, and using urban sewage to cultivate microalgae to produce biodiesel could be helpful to solve this problem. The core technology is the symbiosis system of bacteria and algae in which the dissolved oxygen content played a crucial role.In this paper, microwave radiation was utilized to enhance the oxygen production of Chlorella pyrenoidosa so as to achieve the best operating conditions of algal bacterial symbiotic system. Artificial sewage and urban sewage of university town were chosen as the medium. A microwave device was used to provide radiation. The aim is to get the optimal conditions of microwave radiation, and get the optimization of microwave and magnetic interaction conditio n under which we could achieve the optimum oxygen production by combining with the early results of our research group. Finally, the mechanism research of microwave promoting oxygen production was carried out.Microwave radiation could increase algal biomass and oxygen production. From the consideration of oxygen production effect and economy, microwave worked best when treated microalgae in the logarithmic phase, oxygen production of Chlorella cultivated with artificial sewage increase by 24.86% when treat ed under power 350 W for 40 s, with a 4.88% increase of biomass.In urban sewage, oxygen production increased by 10.71% and biomass increased by 12.37% when treated under power 400 W for 25 s. Orthogonal experiments showed that oxygen production could be increased by more than 36.20% when treated under magnetic field strength 1000 GS for 1 h, and then under microwave power 400 W for 30 s.By testifying the effects of microwave radiation on urban sewage, it was found that microwave radiation had no effect on the ability of oxygen enrichment of water body itself. However, the transmittance of radiated water was increased compared with the control under each wavelength, thereby the illumination environment was improved, COD and ammonia nitrogen concentration w as decreased and the growth of bacteria in sewage was promoted, which was further benefit for the balance algae- bacterial symbiotic system. Moreover, the photosynthesis oxygen production was improved as photosynthetic pigments of Chlorella were increased under microwave irradiation.