Microalgae: a sustainable solution for corporate carbon footprints and wastewater treatment
By Vy Phan, GRC 2024 Global Essay Competition Top 30
Introduction
The relentless momentum of industrial growth has led to a severe imbalance between profit incentives and environmental protection within corporations, as the top 100 corporations are held accountable for up to 71% of the carbon emissions produced (Thomas 2022). Coupled with this is the immense amount of wastewater pollution produced by top corporations, which not only harms local communities but also entails vast energy consumption for water treatment. Wastewater treatment plants (WWTP) lie among the most prominent energy consumers, as it is accountable for 26% of greenhouse gas emissions in the water supply chain (Abdallah 2022).
This necessitates a replacement of traditional energy sources which possess both of the defining metrics: i) having a low-carbon emission nature, and ii) must be cost-effective. Current alternatives (i.e. solar panels, wind turbines, hydroelectricity, etc. ) still are unable to fulfill at least one of the two metrics. In light of these pressing challenges, microalgae emerges as a promising alternative, offering unique dual benefits of carbon capture and wastewater purification. Inherently thriving on carbon dioxide for growth while simultaneously producing biofuels and absorbing pollutants such as nitrogen and phosphorus from wastewater, microalgae has the potential to create an in-house cycle of energy that supports both wastewater treatment and carbon reduction, which has the capacity to revolutionize corporate environmental responsibility.
Mechanisms
Notably, microalgae is an especially potential alternative to traditional electricity sources due to its ubiquitous and low-maintenance nature, possessing higher biomass productivity, and ability to thrive in diverse climatic conditions compared to other terrestrial plants. Because of this photosynthetic efficiency, microalgae can be used to generate an electric current through the development of bio-photovoltaic systems, which harness the electron current in photosynthetic processes. As microalgae produces electrons as a byproduct of photosynthesis, the anode in the electrode system captures the current, producing bioelectricity, and converting chemical energy to electrical energy.
The system capitalizes on the natural flow of electrons between the anode and cathode, directing electrons from algal cells toward the electrode. There is still ongoing research to discover the microalgae strain that can optimize energy yields. The current most promising strains are Chlorella vulgaris and Nannochloropsis, which are noted for their high lipid content and efficient conversion of carbon dioxide into biomass.
Aside from bioelectricity generation, microalgae have a dual capacity for wastewater treatment, a function that would prove to be utilitarian in high waste-producing corporations. Microalgae has the special capacity to fulfill two main functions in wastewater treatment, which are the removal of nutrients and heavy metal compounds. Microalgal culture offers a cost-effective approach to removing nutrients, such as nitrogen (N) and phosphorus (P) from wastewater, given microalgae’s ability to use inorganic N and P for growth. By consuming these compounds, which contribute to eutrophication, for growth, microalgae effectively reduce their concentrations, which aids in nutrient removal and treatment of wastewater. Furthermore, microalgae can remove heavy metals and other toxic contaminants through a process called bioaccumulation. Because algal cells contain functional groups, namely carboxyl, and hydroxyl, that bind to heavy metal ions, they can reduce heavy metal concentration in wastewater (Stefano 2024). Under optimal conditions, highly effective strains, such as Chlorella vulgaris can remove up to 90% of heavy metal ions such as lead and cadmium.
Case studies
Practically, the potential of microalgae has been employed in multiple projects around the world. The most well-known example is the B.I.Q - a Bio Intelligent Quotient 15-story apartment building entirely reliant on algae-generated power. First put in use in 2013 in Hamburg, Germany, the B.I.Q has been regarded as an epitome of green innovations as a response to the problems of high energy consumption and air pollution (Nicky 2013). The building is wrapped in glass panels of microalgae, called a “photobioreactor” that feeds on carbon dioxide and sunlight to produce renewable energy (Denrie 2020). Additionally, the building utilizes excess sunlight not used by microalgae to generate thermal energy for water heating.
Another prominent example is the High-Rate Algal Ponds (HRAP) systems researched and implemented in New Zealand over the past 15 years. High-rate algal ponds are acknowledged as being more efficient than conventional wastewater-purifying ponds, using microalgae and bacteria to remove nutrients and organic compounds in wastewater (Sutherland 2024). The development of these algal ponds has given a viable solution to cost-effectively enhance wastewater treatment, especially in small communities, where wastewater management would otherwise be far-reaching because of its cost. HRAP systems, on the other hand, can be characterized by low maintenance cost, as they can be built with easily available materials, compared to conventional wastewater treatment methods, which require technologies such as activated sludge. Moreover, the process also results in algal biomass that can be converted into other useful bioproducts, namely biogas, and biofertilizers that can be used to generate bioelectricity.
Conclusion
The dual capacity of microalgae for bioelectricity generation and wastewater treatment is transformative for corporate environmental responsibility, creating a closed-loop system that utilizes microalgae’s energy yields. Microalgae can achieve removal rates for nitrogen and phosphorus of 90% and 80%, respectively, reducing nutrients and eutrophication risks while simultaneously creating biomass. This biomass can then be harnessed for bioelectricity using bio-photovoltaic systems as aforementioned. In order for the impacts of microalgae seen in examples such as the B.I.Q in Germany, or HRAP in New Zealand, there needs to be more extensive research, as well as government subsidy in this field. Nevertheless, given the high energy consumption and waste production from big corporations, the microalgae-based solution is a scalable resolution to the current all-time high corporate carbon footprints.
Bibliography
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