UNAB Researcher Develops Innovative Method to Remove Arsenic from Drinking Water

A new method based on biochar derived from marine algae could become a sustainable alternative for addressing arsenic contamination in freshwater sources used for drinking water. This is a less widely known issue that affects several areas of the country.

The innovation was submitted as a patent application to the National Institute of Industrial Property of Chile (INAPI) by Dr. Loretto Contreras, Director of the Laboratory of Ecology and Molecular Biology of Algae (LEBMA) at Universidad Andrés Bello (UNAB), researcher at the Quintay Marine Research Center (CIMARQ UNAB), and researcher at the Millennium Institute SECOS. The proposed technology focuses on principles of the circular economy and public health.

The invention, registered in December 2025, describes a method for adsorbing arsenic from freshwater using biochar obtained from Macrocystis pyrifera, a brown algae species abundant along the Chilean coast, activated with ferric chloride (FeCl₃).

The patent protects both the activated biochar and the process used to produce it, as well as its application in arsenic adsorption systems designed to generate safe drinking water. This development is particularly relevant given the persistence of arsenic contamination in several regions of Chile, mainly associated with natural geological conditions.

Volcanic Zones at Risk

According to a World Bank report published in 2019, between 2011 and 2018 arsenic levels equal to or exceeding the threshold of 0.01 mg/L were recorded in 83 of the 392 localities evaluated nationwide. This value corresponds to the maximum level recommended by the World Health Organization (WHO) for drinking water. “A large portion of northern Chile’s volcanic zone, in particular, had access to drinking water contaminated with arsenic until 2017,” explains Dr. Contreras.

One of the territories studied is the Altiplano–Puna region, where research has shown that arsenic distribution is strongly influenced by the tectonic environment and intense volcanic activity.

In these areas, volcanoes act as emission points that allow arsenic released from the Earth’s crust to reach the surface. From there, it can be transported downhill through groundwater and surface water systems such as rivers, ravines, and streams.

In the Antofagasta Region, while urban populations have access to treated drinking water, the situation is different in rural areas. Recent studies from 2022 indicate that approximately 42% of the rural population lacks a formal water supply. In some localities, arsenic concentrations have been detected that exceed the limits established by both the WHO and current Chilean regulations (NCh 409/1).

A Threat to Human Health

The presence of arsenic in water poses a serious risk to human health. According to Dr. Contreras, “arsenic can cause both immediate and long-term effects, depending on the dose, its chemical form, and the duration of exposure.”

In the short term, consumption of contaminated water may cause gastrointestinal symptoms such as vomiting, abdominal pain, and diarrhea. However, the greatest risk is associated with chronic exposure. “When exposure is prolonged, arsenic can lead to skin lesions, various types of cancer, neurological and cardiovascular disorders, as well as alterations in glucose metabolism, including diabetes,” the researcher explains.

In fact, the International Agency for Research on Cancer (IARC) classifies arsenic compounds as Group 1 carcinogens, meaning they are carcinogenic to humans. “While the effects depend on dose and chemical form, what is concerning is that relatively low concentrations of this metalloid are sufficient to cause serious health effects,” she adds.

How to Remove Arsenic from Water

In response to this challenge, the proposed technology seeks to transform harvesting waste or cultivated biomass from Macrocystis pyrifera into a material capable of efficiently adsorbing arsenic from water.

“This is not only a technological solution, but also a way to convert biomass into a concrete tool to protect public health, integrating nature, technology, and the circular economy,” explains the researcher and principal inventor of the technology.

The process for converting algae into biochar involves subjecting the organic material to high temperatures in the absence of oxygen, transforming it into a carbonized material. This material has a surface particularly suited to capturing arsenic present in water. The biochar is then activated with iron, a key step that enhances its capacity to retain larger amounts of the contaminant.

This technological development is now moving toward practical application. The next phase involves constructing an adsorption filter and evaluating its performance under real-world conditions, with the goal of future implementation in territories affected by naturally occurring arsenic contamination in water sources.