Abstract:
Industrial reverse osmosis (RO) reject streams are a significant source of pollution in
surface water bodies and requires effective treatment. Microalgae-based treatment of RO
reject streams is an interesting approach as it generates valuable biomass concurrent to
bioremediation. This approach also enhances the sustainability of microalgae biomass
production by eliminating the requirement of external nutrient supply and reducing the
freshwater footprint. However, there is a significant gap in research on utilization of RO
reject streams generated by food/pharmaceutical industries for synthesis of microalgaebased
high-value bioproducts. The current study was performed to ascertain the potential
of using RO reject streams from the local food (RO1) and pharmaceutical (RO2)
industries to cultivate Desmodesmus sp. for synthesis of alpha-linolenic acid.
Accordingly, a screening experiment was conducted by growth of Desmodesmus sp. in
RO1 and RO2 under dilutions of 25%, 50%, 75% and 100% (undiluted sample). Results
showed that the highest biomass yields were obtained in 100% RO1 and 100% RO2.
Thereafter, Desmodesmus sp. was cultured in 100% RO1 and 100% RO2 using
photobioreactors with Modified Bold’s Basal media (3N-BBM) used as the control.
Results showed that the use of RO reject streams resulted in a positive effect on the
growth and biochemical composition of Desmodesmus sp. The high lipid content in
biomass showcased that the use of RO reject streams could enhance the sustainability of
microalgae-based alpha-linolenic acid production. However, further research is needed to
study the toxicology effects and assess the techno-economic feasibility of using RO
reject as the growth media.
