By César Eduardo Nájar Almanzor and Danay Carrillo Nieves
Tortillas, tequila, and cheese are some of the most iconic products of Mexican cuisine. However, behind every bite and sip lies a hidden environmental challenge: the generation of large volumes of wastewater during production.
These waters, known as effluents, can have a significant environmental impact if not properly managed.
In Mexico, millions of liters of these wastewaters are produced every year. When discharged without adequate treatment, they contaminate rivers, lakes, and soils—harming the environment, biodiversity, the economy, and the quality of life in surrounding communities.
This challenge presents an opportunity for innovation and sustainability. Inspired by the principles of the circular economy, the Carrillo Biorefinery Lab has developed a project that uses microalgae to treat wastewater, transforming it into valuable resources for various industries.
Backed by FODECIJAL, Tec de Monterrey, and CONAHCYT, this project aims to mitigate environmental impact while opening the door to new products that benefit society.
Wastewater: The Problem
Tortilla production generates a primary waste called nejayote, a liquid left after cooking corn with water and lime to create a soft, nutritious dough.
Tequila production produces vinazas—a liquid byproduct from the distillation process that contains all the leftover fermented agave juice that doesn’t become tequila.
Cheese production results in whey, the residual water left after milk curdles.
Each year, massive volumes of these effluents are produced in Mexico, including approximately 14.4 billion liters of nejayote (enough to fill 5,760 Olympic-sized swimming pools), 6.4 to 7.8 billion liters of vinazas (2,560 to 3,120 pools), and about 2.875 billion liters of whey (1,150 pools). [2]
These wastes contain high levels of nutrients and organic matter. When they enter rivers and lakes, they act as food for native algae, triggering uncontrolled growth that spreads over water surfaces.
This process blocks sunlight, harms aquatic plants, and reduces oxygen levels in the water. Without oxygen, fish and other aquatic life die, disrupting natural ecosystems. Additionally, contaminated waters become dark, emit foul odors, and become unsuitable for human consumption, recreation, or agriculture.
Microalgae: The Solution
Microalgae are microscopic organisms that live in aquatic environments. Like plants, they perform photosynthesis—converting carbon dioxide (CO₂) into energy while releasing oxygen.
They are capable of cleaning wastewater by “feeding” on the excess nutrients that act as pollutants.
This not only removes contaminants from the water but also enables the growth of microalgae rich in proteins, pigments, minerals, fats, and other valuable compounds involved with the food, agricultural, and energy industries.
In collaboration with the Institute of Food Science Research (CIAL) in Madrid and Technische Universität München in Germany, Tec de Monterrey is optimizing the use of microalgae to treat effluents such as nejayote, vinazas, and whey.
This approach combines science and technology to transform problematic waste into useful resources, aligning with the principles of the circular economy.
Wastewater Treatment with Microalgae
The project is structured around three key stages, each designed to address the problem.
Microalgae Adaptation: Although microalgae are highly versatile, they have adjusted to the extreme conditions of wastewater. Researchers use a process called UV mutagenesis, exposing the microalgae to UV light to cause small DNA changes that help them survive harsh environments. The algae go through an acclimatization process, gradually getting used to growing in wastewater until they can thrive in it completely.
Water Cleaning: Once adapted, the microalgae are cultivated directly in the wastewater, consuming the excess nutrients responsible for pollution. This leaves the treated water with a lower environmental impact—ready to be reused for irrigation or other industrial processes.
Microalgae Utilization: After treatment, the microalgae are separated from the water and analyzed to determine their content of proteins, nutrients, minerals, metals, pigments, antioxidants, fats, and other useful compounds. These products can be used as biofertilizers, food ingredients, or biofuels
To make this solution viable on an industrial scale, the team has tested microalgae cultivation in bioreactors (specialized tanks) and larger ponds, allowing them to evaluate the feasibility of applying the process in real-world industries.
So far, results have shown that nejayote is the most favorable wastewater for microalgae growth, enabling the removal of 85% to 100% of contaminants.
Vinazas come second, with 58% to 93% of nutrients removed. Whey still allows for a reduction of 37% to 57% in contaminants.
Currently, additional research is focused on pre-treatment and post-treatment processes to improve results and expand the reach of this technology. [2]
This project shows that microalgae can be harnessed to reduce pollution and generate high-value products, advancing a more sustainable and circular economy.
References
- Nájar-Almanzor, César E., et al. (2023). Microalgae-Assisted Green Bioremediation of Food-Processing Wastewater: A Sustainable Approach toward a Circular Economy Concept. Journal of Environmental Management, 345.
- Nájar-Almanzor, César E., et al. (2024). Chlorella Vulgaris-Mediated Bioremediation of Food and Beverage Wastewater from Industries in Mexico: Results and Perspectives towards Sustainability and Circular Economy. Science of the Total Environment, 940.
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Authors
César Eduardo Nájar Almanzor. PhD student in Biotechnology at Tecnológico de Monterrey.
Danay Carrillo Nieves. Research professor at Tecnológico de Monterrey, affiliated with the Health for People cluster and leader of the Carrillo Biorefinery Lab.
