Experiment on microalgae cultivation in BG11 nutrient solution adding biogas slurry

The way of using biogas slurry to cultivate energy microalgae is favorable to wastewater disposal and can lower the cost of the algae production effectively. 7 strains of microalgae S496, 1067, 1069, C31, Y7, Y3 and W were added to be mixed with nutrient solution (volume ratio of biogas slurry and BG11 was 1:9), and then changes of the growth rate, pH value and nutrients of nutrient solution were studied in this paper. The results showed that all other 6 trains could adapt to culture solutions immediately and came into logarithm growth phase expect Y7. Under the conditions of unregulated medium pH value, pH value of these culture solutions all decreased from 9.20-9.32 to 8.73-9.09 in the first 2-4 days and then started to rise. When pH value declined, growth rate of microalgae increased constantly. When algae were cultivated after 12 days, the final concentrations of algae in culture medium were between 0.310-0.607 g/L. During culture process, the concentrations of NH4-N, Mg, SO42-, Mn, F- and Fe all dropped significantly; NH4-N、Mn、Fe were fully absorbed; Mg2+ dropped 11.47%-87.73%; SO42-dropped 37.30%-62.70%; F- dropped 18.18%-54.55%. This research provides scientific basis for cultivating microalgae in mixing biogas slurry.