Blending high concentration of anaerobic digestion effluent and rainwater for cost-effective Chlorella vulgaris cultivation in the photobioreactor

Abstract

The possibility of utilizing blended wastewaters from raw anaerobic digestion effluent (RADE) and rainwater (RW) was investigated for cost-efficient Chlorella vulgaris (C. vulgaris) cultivation in photobioreactor (PBR). Two-sequencing batch PBRs were started-up with RADE and mixed wastewater (40% ADE + 60% RW). The result indicated that C. vulgaris growth and contaminants removals were inhibited due to the high concentration of nutrient and organic pollutants in PBR (RADE). Comparatively, PBR (ADE + RW) obtained satisfying treatment efficiencies with the maximum removals of NH4+-N (94.61 ± 1.83%), PO43−-P (95.71 ± 1.73%) and COD (86.72 ± 1.72%). RW supplemented trace elements (Fe, Mn, Zn, Cu), which accelerated C. vulgaris photosynthesis with high lipid productivity accumulation (65.72 ± 1.98 mg/L⋅day) in PBR (ADE + RW). This study firstly demonstrated the potential of using mixed wastewater (ADE + RW) for cost-efficient C. vulgaris cultivation with simultaneous actual ADE wastewater treatment in PBR.