Screening And Acclimation Oil-rich Microalgae For Removing Nitrogen Oxide Treatment In Industrial Waste Gas

Microalgae can use CO2 in coal-fired flue gas as a carbon source during the growth process,thereby removing CO2 from coal-fired flue gas and reducing greenhouse gas emissions.Nitrogen oxides are another contaminant in coal-fired flue gases that are toxic and can inhibit algal growth.Therefore,the purpose of this study is to determine the tolerance of different algae to nitrogen oxides and the adaptability of algae to high concentrations of nitrogen oxides,and use the microalgae to remove nitrogen oxides in industrial waste gas.In order to ensure the efficiency of microalgae screening and acclimation process,a new microbubble-induced algae screening system was developed.The results show that the mixing,cycling and mass transfer of the system are greatly enhanced compared with the conventional conical flask and the traditional reactor.The KLa values of the microbubble induced system are 4 times higher than the traditional reactor.The results of this research have also revealed that higher algae growth rate can be achieved by applying this system,which was approximately 20%higher than the specific growth rate in conventional systems.The screening experiment determined that at flux of 1.22 m/s.Twelve algae strains were screened in this research namely Chlorel la protothecoides,Chlorel la pyre noi do sa,Chlorella vulgaris,Scenedesmus obliquus,Chlamydomas reinhardtii,Chlorella sp.,Nannochloropsis oculata,Nannochloropsis oculata,Dunaliella sp.,Chlorella sp.,Dianchi Lake sewage inlet algae.The research discovered that nitrogen oxides concentrations of 12870mg/m3 could cause severe inhibition to almost all strains.However,Chlorella protothecoides,Chlorel la pyrenoidosa,Chlorella vulgaris,Scenedesmus obliquus,Chlorella sp.,Dunaliella sp.showed better tolerance to nitrogen oxides.And Chlorella protothecoides,Chlorel la pyrenoidosa,Chlorella vulgaris,Scenedesmus obliquus,were further investigated for their tolerance to nitrogen oxides and their acclimation capacities.The ability of microalgae to adapt to nitrogen oxides was studied by measuring the growth rate of algal biomass at different nitrogen oxides concentrations(9900 mg/m3,12870 mg/m3).The results showed that the concentration of nitrogen oxides(NOx)had inhibitory effect on four microalgaes,but it showed strong adaptability through two acclimations,especially Chlorella protothecoides.Scenedesmus obliquus showed the significantly increased ability to adapt.The effects of nitrogen oxides on the microbial production of microalgae were also studied by NMR and GC-MS,and discussed in this research.