Abstract:
Microalgae biomass production for food and fuel applications necessitates the use of
resources such as water and nutrients, raising sustainability concerns. This study aimed
to integrate food industry wastewaters as a source of nutrients and water for microalgae
cultivation while simultaneously performing bioremediation. Nonetheless, wastewaterbased
microalgae cultivation requires the identification of suitable wastewater streams,
nutrient loads, and appropriate media sterilization methods to prevent culture failure due
to contamination. In the current study, the microalga Desmodesmus sp. was cultivated in
wastewater-based media for synthesis of the nutritionally-valuable alpha-linolenic acid.
This study is the first in literature wherein a comparative assessment was performed
between autoclaving and filtration as methods for wastewater sterilization.
A screening experiment for Desmodesmus sp. growth was performed using brewery
wastewater (BrW), coconut processing industry wastewater (CW) and biscuit wastewater
(BiW) obtained from the food industry, under 25%, 50%, 75%, and 100% (undiluted)
concentrations. Undiluted BiW was the most suitable media, as it resulted in the highest
final biomass yields. Thereafter, undiluted BiW sterilized by autoclaving and filtration was
used to culture Desmodesmus sp. in photobioreactors with Modified Bold’s Basal Media
used as the control. BiW showed higher biomass yields and specific growth rate
compared to the control. A higher lipid productivity of 16.78 mg L d was exhibited in
autoclaved medium as compared to 9.92 mg L d in the filtered medium. Thus, BiW
sterilized via autoclaving was identified as a promising growth medium for alpha linolenic
acid production from a circular economic perspective.
