Remove antibiotics in wastewater

In recent years, several compounds have been identified in wastewater that, due to their chemical characteristics, cannot be partially or completely degraded through conventional biological processes such as wastewater treatment plants.

These compounds are called “emerging contaminants”, and this group includes, among others, antibiotics, substances that alter the body’s hormonal system, some personal care products and pesticides. These are natural or synthetic substances of massive use in humans and animals.

In the case of antibiotics, there are numerous works that have studied their effect on the environment and on the appearance of bacterial strains that are more resistant to medical treatments, which makes the contamination of wastewater by this type of drug a health issue. public. For example, in 2019, after analyzing samples taken from 711 sites in 72 countries on five continents, a group of researchers from the University of York (United Kingdom) detected traces of these substances in 462 places.

“Given this scenario, public policies should be aimed at containing, correcting, mitigating and controlling the contamination of water sources,” warns Edison Alexander Agudelo, from the National University of Colombia (UNAL) in Medellín. “In fact, the Inter-American Development Bank warned in 2018 about the need for Latin America to protect all water sources, both surface and groundwater, since many of these are the drinking water supply for the population.”

The point is that, once the problem was discovered, scientists also realized that removing these and other drugs from the water in wastewater treatment plants is not an easy task.

Pharmacological contamination of drinking water is an emerging problem. (Photo: Amazings/NCYT)

Professor Santiago Cardona, from the Faculty of Mines of the UNAL, Medellin, indicates that “antibiotics are very complex and large molecules; furthermore, conventional plants are designed to remove molecules of lesser chemical complexity”.

In order to optimize the efficiency of wastewater treatment plants, Engineer Agudelo developed a kinetic model to mathematically simulate how meropenem would degrade with a proposed catalytic ozonation system.

The model was validated in a pilot-scale system with synthetic hospital wastewater –with characteristics similar to those of wastewater– from a high-complexity hospital in Medellín. Total elimination of the antibiotic and a 90% reduction in the initial chemical oxygen demand (COD) in the system, an indicator used to measure the degree of contamination in the water, were obtained.

Likewise, the acute toxicity of the water decreased by 100% until it became innocuous for the test microorganisms, which were E. coli and Staphylococcus aureus, bacteria that cause gastrointestinal infections and meningitis.

Similarly, they are microorganisms that in some strains have shown resistance to the antibiotics with which they were treated, an aspect that is also part of the problematic presence of antibiotics in wastewater, because their residues have typically been found near the wastewater treatment plants, an ideal setting for both elements to coexist and adapt.

For this reason, systems such as the one designed by engineer Agudelo to facilitate the elimination of these polluting agents from wastewater can become a fundamental tool for health authorities in the challenge that microbial resistance represents. (Source: UNAL)