Phycoremediation of anaerobic digested dairy manure wastewater using Chlorella vulgaris

Abstract

Microalgae have been used in a process of pollutants removal from wastewater, a process known as phycoremediation. In this study we used Chlorella vulgaris to remediate anaerobically digested dairy manure wastewater (ADDMW) which contained a high concentration of nitrogen and phosphor. The light intensity of 50, 100 μmol/m2s and sunlight were applied to the microalgal culture. Percentage of reduction in ammonium and orthophosphate content in the media were measured. Protein content in microalgal biomass was measured using hot-TCA method. At the light intensity of 100 μmol/m2s, microalgal productivity in biomass reached its high level i.e. 0.149 ± 0.03 gL−1d−1 with its protein content 10.74 ± 0.63%. However, the highest specific growth rate (0.343 ± 0.034 d−1) with the shortest doubling time (2.028 ± 0,141 d) were reached under sunlight conditions. The reduction rate of ammonium and orthophosphate content in the medium were 36-48 mgL−1h−1 and 5-6.62 mgL−1h−1 respectively in a culture which was inoculated with C. vulgaris. C. vulgaris can be used as phycoremediator for ammonium and orthophosphate, and ADDMW medium can supply C. vulgaris with appropriate nutrients. Moreover, light intensities of 50 and 100 μmol/m2s can be used in the indoor culture of microalgae.