My Contribution to the Circular Economy

A contribution to the circular economy; fish excrete nutrients which algae take up and are then fed to Daphnia magna which is then fed back to fish.

A graphical abstract of the project, fish excrete valuable nutrients which microalgae take up.  Daphnia eat the microalgae then are fed to fish.
The basic concept in my paper is that aquaculture effluent (fish farming wastewater) is high in excreted phosphorus and nitrogen which cause eutrophication in lakes and must be managed.  Algae uptake nitrogen and phosphorus into their biomass and Daphnia magna eat algae which can then be fed back to shrimp and fish larvae. 

Project Summary

Recirculated aquaculture systems (RAS) are often seen as the future of aquaculture because of well-documented issues surrounding wild capture or open-net farming.  One engineering problem for RAS are nutrient discharges, which cause water eutrophication (water body senescence or aging and death).  Microalgae are one of the causes of eutrophication, however, microalgae directly incorporate nutrients such as nitrogen and phosphorus as well as carbon dioxide directly into their biomass.  Removing microalgae from water is extremely resource intensive but Daphnia magna eat (harvest) microalgae and are a high value fish feed.  These D. magna can then be fed to shrimp or fish larvae presenting a nice bio-circular economic production system.   This was essentially a lab scale proof of concept for this system.  The scientific details are published in the Science of The Total Environment. In future posts, I plan on going into detail some of the motivations behind this project such as eutrophication and the circular economy as well as on the ramifications of this work. 


Seriously, people are wonderful and I sincerely thank these mentors.
Standing on the shoulders of giants is grandiose for this work but I’m glad to have had tremendous help to slightly push the boundaries of knowledge outwards a little.

I owe many thanks to several people and organizations for this to include Borja Valverde Pérez who has long worked with microalgae for resource recovery from wastewater and served as the principle advisor; Xinyu Zhu who showed me many lab techniques; Marja Koski who allowed me to work on a related project and helped me tremendously with Daphnia magna and aquaculture; Irini Angelidaki who was extraordinarily generous with her resources; as well as Arnaud Dechesne, Anna Łukaszewicz, Karl Gorzelnik, Keya Mukherjee, Caitlin Nyhus, and the good people of Pease New Hampshire.

Musholm A/S was extremely generous in providing the wastewater used in this study.

The research was supported through the InWAP project grant by the Danish Innovation Foundation, Denmark and Department of Biotechnology, Government of India (Grant no. BT/IN/Denmark/61/KM/2018-19).


Disclaimers get tiring.
In the future I really should make an omnibus disclaimer then link to it from every page.

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