Anaerobic digestate as a low-cost nutrient source for sustainable microalgae cultivation: A way forward through waste valorization approach

Abstract: 

To suffice the escalating global energy demand, microalgae are deemed as high potential surrogate feedstocks for liquid fuels. The major encumbrance for the commercialization of microalgae cultivation is due to the high costs of nutrients such as carbon, phosphorous, and nitrogen. Meanwhile, the organic-rich anaerobic digestate which is difficult to be purified by conventional techniques is appropriate to be used as a low-cost nutrient source for the economic viability and sustainability of microalgae production. This option is also beneficial in terms of reutilize the organic fraction of solid waste instead of discarded as zero-value waste. Anaerobic digestate is the side prod- uct of biogas production during anaerobic digestion process, where optimum nutrients are needed to satisfy the physiological needs to grow microalgae. Besides, the turbidity, competing biological contaminants, ammonia and metal toxicity of the digestate are also potentially contributing to the inhibition of microalgae growth. Thus, this review is aimed to explicate the feasibility of utilizing the anaerobic digestate to cultivate microalgae by evaluat- ing their potential challenges and solutions. The proposed potential solutions (digestate dilution and pre- treatment, microalgae strain selection, extra organics addition, nitrification and desulfurization) corresponding to the state-of-the-art challenges are applicable as future directions of the research.

Author(s): 
Chi Cheng Chong
Yoke Wang Cheng
Syukriyah Ishak
Man Kee Lam
Jun Wei Lim
Inn Shi Tan
Keat Teong Lee
Keywords: 
Anaerobic digestate
Organic waste
Nutrients
Microalgae cultivation
Inhibition
Article Source: 
Science of the Total Environment 803 (2022) 150070
Category: 
Aquaculture methods
Basic Biology
Microalgae