Three Species Of Microalgae Utilized For DE-NO_x And Carbon Fixation Of Flue Gas From Coal-fired Power Plant

Flue gas from coal-fired power plant contains plenty of inorganic pollutants such as CO2,NOx and SO2,which have caused serious air pollution in terms of smog problem,green house effect and acid rain.Compared to traditional physical-chemical treatment of flue gas,the microalgal method could achieve simultaneously elimination of CO2 and NO which could be transformed to valuable biomass through photosynthesis process.As several functional microalgae species have been reported for DeNOx and carbon fixation of flue gas,microalgal treatment of flue gas has been paid more and more attention.It is significant to exploit new functional microalgae specie superior in biomass accumulation and NOx assimulation,and to conduct comprehensive research on the properties of DeNOx and carbon fixation.To investigate the properties of carbon fixation,DeNOx of flue gas and pollutant elimination of domestic sewage,we mainly selected Micractinium sp.PFA,Chlorella sp.L2 and Kirchneriella sp.PFB,which are isolated from different natural enviorment.Co-solvent Fe(II)EDTA and domestic sewage were also adapted to promote the microalgal performance on DeNOx and carbon fixation.The PFA and PFB show dramatic ability of biomass accumulation and carbon fixation with an average biomass productivity of 0.090 g/(L·d)and 0.110 g/(L·d),and CO2 fixation rate of 0.273 g/(L·d)?0.249 g/(L·d).Cultivated in mixed water by BG11 and wastewater,microalgal biomass accumulation could be elevated 20~50% on account of adequate organic carbon and nitrogen source.PFA and PFB could achieve 0.155 g/(L·d)and 0.136 g/(L·d)biomass productivity with the final biomass accumulation of 1.638 g/L and 1.569 g/L.All the three microalgae show steady excellent DeNOx ability,while the strains L2 is the best.PFA,L2 and PFB could achieve 16.62%,17.66% and 14.30% NO elimination in simulated flue gas,while they are 27.88%,22.96% and 24.23% in realistic flue gas.13% increase are realized when the gas-liquid contact area is enlarged by means of minifying pumping bubble volume and 78.03% NO elimination is realized when the gas hold-up time was extended through series connection.20%~30% promotion can be achieved in the addition of co-solvent Fe(II)EDTA,with which PFA,L2 and PFB could achieve 59.77%,62.76% and 48.18% NO elimination.In aspect of sewage treatment,PFA,L2 and PFB strains perform fabulous elimination of nitrogen and phosphorus.98% NH4-N elimination is realized within 5 days,while the final NH4-N ? 0.1 mg/L;TN elimination of all the species can reach 80%,while PFA and L2 can reach 90%;TP elimination can reach 96% within only 3 days in each system,while the final TP ? 1 mg/L;the pH of each system maintains 6~7 in treatment of realistic flue gas.All the indexes mentioned above are consistent with national comprehensive wastewater discharge standard,A level of first class standard.By comprehensive comparison,we conclude that Micractinium sp.PFA can be selected as ideal microalgae specie utilized for DeNOx and CO2 fixation of flue gas in terms of its excellent carbon fixation in domestic sewage and dramatic NO elimination of flue gas,while Chlorella sp.L2 is more applicable for DeNOx in BG11 and Kirchneriella sp.PFB is better utilized for biomass accumulation in wastewater.