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

• Published in: The Science of the total environment 2022-01, Vol.803, p.150070-150070, Article 150070
• Main Authors: Chong, Chi Cheng, Cheng, Yoke Wang, Ishak, Syukriyah, Lam, Man Kee, Lim, Jun Wei, Tan, Inn Shi, Show, Pau Loke, Lee, Keat Teong
• Format: Article
• Language: English
• Subjects: Anaerobic digestate; Inhibition; Microalgae cultivation; Nutrient; Organic waste
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.150070

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 product 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 evaluating 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. [Display omitted] •Microalgae is a sustainable source for future biofuel production.•Digestate from anaerobic digestions is an alternative nutrient to grow microalgae.•The effect of digestate properties towards the growth of microalgae are discussed.•Potential ways to enhance the microalgae growth using digestate are recommended.