Wastewater reclamation and theupcycling of its nutrients into microalgae can be optimized, to obtain more valuable biomass, thanks to the innovative method developed by a group of Chinese and American researchers (Wang et al., 2021). (1)
Wastewater and microalgae
Microalgae growth in wastewater is possible due to the presence of the nutrients-nitrogen, phosphorus, organic carbon-in wastewater. However, the resulting algal biomass can become contaminated with bacteria that reduce the potential for use. In addition to having ‘often a low lipid and carbohydrate content, which reduces its value as feed for livestock or as a precursor for higher value chemical production.’
The researchers therefore experienced a reversal of the process. Instead of placing the microalgae in waste water, they extracted nutrients from food wastewater from Washington University ‘s food service with a bio-electrochemical system and then fed them to microalgae grown separately in a photobioreactor.
The result
The quality comparison of algal biomass obtained by this upcycling method is stark. ‘The results of this study demonstrated an effective approach to extract nutrients from wastewater for increased microalgae growth and improved biomass quality,’ the authors explain.
The harvest thus obtained, in comparison with that derived from soaking the algae in the same food wastewater, shows
- 8.3 times higher biomass density,
- 1.4 times higher lipid content (from 18.5 to 26.2 percent),
- a microalgae concentration of 90 percent of the biomass, compared with about 30 percent from cultivation in food wastewater.
Marta Strinati
Notes
(1) Zixuan Wang, Christopher J. Hartline, Fuzhong Zhang, Zhen He (2021). Enhanced microalgae cultivation using wastewater nutrients extracted by a microbial electrochemical system, Water Research, Volume 206, 2021, 117722, ISSN 0043-1354, https://doi.org/10.1016/j.watres.2021.117722.
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
