A Novel Algae Synergy for Carbon Capture and Water Purification

Two years ago, my science partner and I discovered lead in the water at our school and in the soil around our community in the Yukon. We had been drinking that water every day. That moment changed everything for me. It sparked a campaign for environmental safety that gave our community a voice, and it sparked a question I couldn't let go of: what if clean water and clean air were accessible everywhere?

Algae can capture CO₂ and remove pollutants from water naturally. But their efficiency has always been too low for real-world, large-scale use. Nobody had found a way to push algae far beyond their biological limits. That gap is what my project aims to fix.

I spent months reviewing research and exploring solutions before landing on a completely novel combination: alginate, a biopolymer derived from seaweed, paired with graphene quantum dots (GQDs), nanomaterials known to enhance light absorption in plants. No previous study had ever tested this synergy in algae. I designed 32 custom bottles, cultured Chlorella vulgaris across multiple treatment groups, and measured how each additive combination affected algal growth, photosynthetic performance, CO₂ uptake, and pollutant removal.

This project matters because climate change and water contamination are among the most urgent challenges humanity faces. If enhanced algae can be deployed at scale, they could help repair damaged environments around the world, not just in the Yukon, but in every community that breathes polluted air and drinks contaminated water.

I began with extensive background research, reading studies on alginate oligosaccharides, graphene quantum dots, microalgae cultivation, and bioreactor design. This research led me to the hypothesis that pairing alginate with GQDs could synergistically supercharge algae. An idea I then brought to a university professor in the field of chemistry, who reviewed my proposed system and validated both its scientific rationale and experimental design before I began.

I grew a large starter culture of Chlorella vulgaris in a single transparent tub inside a hydroponic tent, using grow lights, fans, air pumps, and aeration tubing to maintain stable conditions. Once the culture reached healthy dark green density, I ran a small preliminary experiment to decide which of two chitosan powders (B59 and chitosan lactate) performed better with my algae, testing both at two concentrations across four labeled jars and observing nitrate reduction and algae health over five days before selecting B59 for the main experiment.

I then distributed my algae culture into 32 labeled 400 mL bottles. Each bottle received a unique combination of additives (chitosan, alginate, graphene quantum dots, and algae) across both clean and polluted algae conditions. The polluted algae was a KNO₃ solution I prepared to simulate nitrate contamination. I ensured all environmental conditions were held constant throughout the testing.

Every day I collected photos of all 32 bottles under consistent lighting and recorded nitrate test strip readings by taking a picture of the strip. At the end of the experiment I collected 100 mL algae samples from the top-performing bottles and measured settled biomass height over multiple days. I then wrote custom code to apply gray-scale normalization across all bottle, test strip. and biomass cylinder images. After converting visual data into consistent numerical scores I could then graph and compare across every treatment group, which was most effective.

Across all 32 bioreactor cultures, the results were clear and consistent: not all additive combinations improved algal performance. Several treatments, including chitosan alone and some GQD-only groups produced only modest changes compared to control bottles. One combination stood out across every metric measured: alginate paired with graphene quantum dots (GQDs).

Pollutant removal: In the polluted water bottles, Bottle #7 (alginate + GQDs + algae + pollutant) demonstrated the most effective nitrate reduction across all eight polluted algae bottles. Gray-scale image analysis of nitrate test strips confirmed the trend quantitatively. This bottle outperformed every other treatment combination, including the chitosan variants and the GQD-only bottles.

Algae growth and biomass: In the non-polluted bottles, Bottle #23 (alginate + GQDs + algae) achieved the highest grey scale score (72 on the darkness scale) in the biomass cylinders, the darkest, densest algal culture, indicating maximum photosynthetic activity and cell density. This was reproduced consistently across daily color observation charts. Biomass settled in cylinder #23 reached 0.6 cm, the highest of all non-polluted groups. The alginate + GQD combination effectively doubled biomass production compared to the control just algae bottle.

Reproducibility across conditions: Critically, the winning combination (alginate + GQDs) was the top performer in both the clean and polluted water setups. Bottle #7 (polluted) and Bottle #23 (clean) contained the same additive formulation. The consistency of results across these two entirely different environmental conditions confirms that the synergy is not coincidental, it is reproducible and robust.

Image analysis validation: A custom gray-scale normalization pipeline was applied to photos of all bottles, biomass cylinders, and nitrate test strips. Bar charts of grey-scale values across all cylinders and strips show a clear visual separation between the alginate + GQD group and all others. This method converted subjective color observations into quantitative, comparable numerical data, adding scientific rigor to an otherwise visual measurement.

Mechanistic interpretation: The results align with the proposed mechanism: alginate acts as an external carbon source and metabolic stimulant, encouraging faster cell division and enhanced nitrate uptake. GQDs increase light absorption and improve electron transport efficiency within the chloroplasts, giving the algae more energy to grow and remediate. Together, they create a biological environment where neither limitation (energy nor metabolic drive) is the bottleneck. The synergy is additive and exceeds what either component produces independently.

These findings answer the central research question with strong evidence: yes, alginate and graphene quantum dots can synergistically push Chlorella vulgaris far beyond its natural performance limits, with a real impact on carbon capture and water purification at a much bigger scale.

This experiment demonstrates that a simple, low-cost additive combination (alginate and graphene quantum dots) can reliably and significantly enhance the biological performance of Chlorella vulgaris beyond its natural limits. The key conclusion is not just that one bottle performed better, it is that the same formulation dominated in both clean and polluted water environments, confirming a reproducible and mechanism-driven synergy rather than a statistical fluke.

The implications are significant. Algae are already recognized as one of the most promising natural tools for carbon sequestration and water remediation. They are sustainable, fast-growing, and biodegradable. The barrier to deploying them at meaningful scale has always been efficiency. This project demonstrates a path around that barrier using materials that are commercially available, relatively inexpensive, and biodegradable.

If this formulation holds up in larger systems such as industrial bioreactors, municipal wastewater treatment, agricultural runoff basins, or decentralized units in remote communities, it could meaningfully contribute to two of the world's most pressing environmental challenges simultaneously: excess CO₂ in the atmosphere and pollutant contamination in water bodies. This project began as a response to a local water crisis in the Yukon and has grown into a framework with global potential.

The finding is novel. No previous study has tested this combination of alginate and GQDs in algal bioreactors. This project opens a new direction for algae enhancement research with real-world deployment in mind from the very beginning.

Next steps include quantifying the precise mechanisms behind the alginate–GQD synergy by measuring light absorption spectra and carbon fixation rates directly. I will optimize additive concentrations and test the formulation in larger bioreactor volumes under variable industrial conditions. I plan to collaborate with environmental engineers to assess feasibility in municipal wastewater and agricultural runoff settings. A lifecycle and cost analysis will evaluate commercial viability. Finally, I intend to reach out to additional specialists in nanomaterial science and algal biotechnology to validate and expand these findings.

I would like to sincerely acknowledge and thank my parents for providing mental support, along with the physical aspect of my project. I would also like to thank ChitoLitic’s CEO, Michel Lockhart for providing me with the necessary amount of chitosan to power my project, and for providing his expertise in the field. I would also like to thank my Biology teacher, and science teacher for supplying some of the necessary material and expertise in the field. And finally thankyou to Vladmire- Proffesor, for looking over my project and providing your insight in the beggining.

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Zhang, Y., Li, J., & Wang, X. (2022). Effects of nitrogen-doped graphene quantum dots applications on yield and quality in grape varieties. Journal of Plant Growth Regulation, 41(3), 1125–1138. Springer Nature. https://doi.org/10.1007/s00344-021-10487-9 (doi.org in Bing)

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Zhang, C., Wang, X., & Li, Y. (2021). Nanomaterial-mediated enhancement of photosynthetic efficiency in microalgae: Mechanisms and applications. Biotechnology Advances, 49, 107756. (General nanomaterial–algae interaction paper; supports your electron‑transport explanation.)

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Huang, Y., Li, X., & Chen, F. (2022). Nanotechnology-assisted enhancement of microalgal carbon fixation: Progress and perspectives. Bioresource Technology, 351, 127042. (Matches your carbon‑capture improvement results.)