Assessing the potential of Chlorella sp. phycoremediation liquid digestates from brewery wastes mixture integrated with bioproduct production

Abstract

Digestates from different anaerobic digesters are promising substrates for microalgal culture, leading to effective wastewater treatment and the production of microalgal biomass. However, further detailed research is needed before they can be used on a large scale. The aims of this study were to investigate the culture of Chlorella sp. in Digestate_M from anaerobic fermentation of brewer's grains and brewery wastewater (BWW) and to explore the potential use of the biomass produced under different experimental conditions, including diverse cultivation modes and dilution ratios. Cultivation in Digestate_M initiated from 10% (v/v) loading, with 20% BWW, obtained maximum biomass production, reaching 1.36 g L^-1 that was 0.27g L^-1 higher than 1.09 g L^-1 of BG11. In terms of Digestate_M remediation, the maximum removal of ammonia nitrogen (NH₄ ⁺-N), chemical oxygen demand, total nitrogen, and total phosphorus reached 98.20%, 89.98%, 86.98%, and 71.86%, respectively. The maximum lipid, carbohydrate, and protein contents were 41.60%, 32.44%, and 27.72%, respectively. The growth of Chlorella sp. may be inhibited when the Y(II)-F_v/F_m ratio is less than 0.4.

Keywords: Chlorella sp.; biomass composition; brewery wastewater; brewer’s grains; digestate; photosynthetic fluorescence parameters.