Integration of food industry wastewater for cultivation of desmodesmus sp. to synthesize alpha-linolenic acid

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.