Nutrient recovery from food industry solid waste for cultivation of the microalga Desmodesmus sp. for production of alpha-linolenic acid

Abstract

The generation of food waste by the food processing industry poses significant environmental and economic challenges globally. This study investigated the potential of utilizing industrial food waste as a source of nutrients for cultivation of the microalga Desmodesmus sp. to produce value-added biomass rich in alpha-linolenic acid. The objectives of the study were to identify the type of food waste and dilution factor of food waste hydrolysate to maximize biomass and alpha-linolenic acid yields, and assess the efficacy of nutrient recovery. The current study is the first in reported literature to utilize industrial food waste for synthesis of microalgae-based alpha-linolenic acid. First, a screening experiment was performed for growth of Desmodesmus sp. in hydrolysates of brewery waste (BrW), biscuit waste (BiW), and Thriposha waste (TW) with four dilution factors; 25%, 50%, 75% and 100% (undiluted hydrolysate). Higher biomass yields were achieved in all waste types compared to the control medium (modified Bold’s Basal media; 3N-BBM), with the maximum yield obtained using 100% TW. Thereafter, Desmodesmus sp. was cultured in photobioreactors using 100% TW, with a 3N-BBM control. The biomass growth rate and specific growth rate achieved in 100% TW hydrolysate were 0.503 g L d and 0.214 d respectively, which were significantly higher than the control. Biomass analysis showed that a significantly higher lipid content was present in the 100% TW-cultivated biomass, suggesting a higher alpha-linolenic acid extraction potential. Nevertheless, further research on techno-economic feasibility assessment and toxicology analysis is required prior to large-scale adoption of this process.