Soil could Filter Antibiotics from Treated Wastewater, Protecting Groundwater

Soil may be a natural filter that can act as a tertiary treatment for wastewater, preventing antibiotics from contaminating groundwater, according to researchers who conducted a study at Penn State's Living Filter.

Researchers analyzed the fate and transport of three antibiotics important to human health — sulfamethoxazole, ofloxacin and trimethoprim — in soil and groundwater at the Living Filter, a 50-year-old wastewater reuse system that spray-irrigates treated effluent from the University Park campus' sewage treatment plant on 600 acres of farm and forest. In general, researchers found that each antibiotic behaved differently when exposed to the soil profile, but they gained insight into how soil might enhance wastewater treatment.

Currently, most treated wastewater around the world is discharged by sewage treatment plants into rivers. However, most of those facilities are not capable of completely removing pharmaceuticals such as antibiotics. As a result, many rivers carry low levels of pharmaceuticals that are suspected of harming aquatic life. In waterways that provide drinking water, low levels of antibiotics may pose human health risks, contributing to the development of antibiotic resistance.

An alternative to discharging treated wastewater into waterways and possibly contributing to antibiotic resistance and other ecological problems is to spray it on land, as Penn State has been doing for more than five decades at the Living Filter, noted Jack Watson, professor of soil physics and soil biogeochemistry. His research group in the University's College of Agricultural Sciences led the study.

"With low-levels of antibiotics in the environment due to the release of wastewater treatment plant effluent into waterways, concern is rising about impacts on human health," he said. "Soil, due to its physical and chemical nature, in many cases could offer another level of treatment to remove antibiotics from treated wastewater. This study begins to evaluate the effectiveness of that concept."

There are few facilities like Penn State's Living Filter in the eastern U.S., but wastewater reuse to provide irrigation water and to recharge aquifers is a common practice in the arid American West and in the deserts of the Middle East, pointed out lead researcher Alison Franklin, a doctoral student in soil science and biogeochemistry.

Franklin collected soil samples at a site on the Living Filter that had not received irrigation for seven months, and then at the same site following one irrigation event and again after 10 weeks of irrigation. Franklin also took groundwater samples three times a year over five years to capture seasonal variability.

The researchers typically found sulfamethoxazole at the highest concentrations in wastewater treatment plant effluent with ofloxacin and trimethoprim at lower concentrations. In the soil, ofloxacin was present at the highest concentrations after seven months without irrigation, but sulfamethoxazole did not reach concentrations higher than ofloxacin until after effluent was continuously applied. Trimethoprim was only detected in soil following 10 weeks of effluent irrigation.  

Penn State's Living Filter is a 50-year-old wastewater reuse system that spray-irrigates treated effluent from the University Park campus's sewage treatment plant on 600 acres of farm and forest. Unique in the eastern United States, the facility provides opportunities for researchers to conduct a wide range of water-quality experiments.
Image: Penn State 

These results suggest that ofloxacin may remain in the soil for long periods of time, Franklin explained, while sulfamethoxazole and trimethoprim may not remain after effluent irrigations stop.

Groundwater concentrations were typically much lower than soil or wastewater effluent concentrations with only sulfamethoxazole being found consistently.

"Given that antibiotics interacted with the soil profile and groundwater concentrations were frequently more than a 1,000-fold lower than effluent, the soil profile appears to be an adequate tertiary treatment for wastewater treatment plant effluent," she said. "That would lead to improved water quality and protection of human health."

The findings of the research, which were published today, Sept.10, in the Journal of Environmental Quality. 

Read the full article at: Penn State University

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Taxonomy

• Irrigation
• Irrigation and Drainage
• Waste Water Treatments
• Wastewater Treatment
• Pharmaceuticals
• Pharmaceuticals
• Irrigation and Drainage

2 Comments

1. Yes the soil can serve as a filter for all pollution. But after a while it will saturate and infiltrate this pollution to the groundwater. The heavy rainfall will also facilitate the infiltration and dispersion in the subsoil of all the pollution contained in the wastewater. The vocation of a filter is to retain. When he clogs he regurgitates what he holds back. Nobody is there when the ground will send all the pollution collected to groundwater. In addition to sewage pollution, chemical pollutants and their interaction with oxygen must be added. With ideas like these we can do everything without predicting the impact it will have over time

2. Oui le sol peut servir de filtre à toutes les pollutions. Mais au bout d'un certain temps il va saturer et infiltrer cette pollution vers les nappes phréatiques. Les fortes précipitations pluviales vont également faciliter l'infiltration et la dispersion dans le sous sol de toutes les pollutions contenues dans les eaux usées.

   La vocation d'un filtre c'est de retenir. Quand il colmate il régurgite ce qu'il retient. Personne n'est là présent au moment ou le sol enverra toute la pollution amassé vers les nappes phréatiques.

   En plus de la pollution  des eaux usées il faut y ajouter les pollutions chimiques et leur interaction au contact de l'oxygène.

   Avec des idées comme celles ci on peut tout faire sans prévoir l'impact que cela aura dans le temps