In the heart of Murcia, Spain, a team of researchers led by Pilar Truchado from the Research Group on Microbiology and Quality of Fruit and Vegetables at CEBAS-CSIC is tackling a pressing issue in sustainable agriculture: the safe reuse of wastewater for irrigation. Their latest study, published in the journal ‘Frontiers in Microbiology’ (translated from Spanish as ‘Frontiers in Microbiology’), delves into the risks and mitigation strategies of antimicrobial resistance (AMR) in reclaimed water, with significant implications for the energy sector and beyond.
As global water scarcity intensifies, the agricultural industry is increasingly turning to wastewater reuse for irrigation. However, this practice carries potential public health risks due to the dissemination of antimicrobial resistance. Truchado and her team set out to evaluate the effectiveness of four tertiary wastewater treatment technologies in reducing extended-spectrum β-lactamase-producing Escherichia coli (ESBL-E. coli) and antimicrobial resistance genes (ARGs) in reclaimed water.
The technologies under scrutiny were peracetic acid (PAA), PAA combined with low-intensity ultraviolet-C (PAA/UV Low), high-intensity UV-C (UV High), and ultrafiltration (UF). The results, while promising, also highlight the need for further optimization. “While all treatments significantly reduced ESBL-E. coli and ARGs, complete elimination was not achieved in any wastewater treatment plant,” Truchado explains. Among the treatments, UF demonstrated the highest removal efficiency, followed by UV High. PAA and PAA/UV Low were less effective, indicating that the choice of treatment technology can significantly impact the safety of reclaimed water.
The study also found that while absolute ARG levels were reduced, their relative abundance remained stable or showed minimal decline. This suggests a persistent environmental reservoir of resistance genes, a finding that underscores the complexity of mitigating AMR risks in water reuse systems. The most frequently detected ARGs were associated with tetracyclines, quinolones, and sulfonamides, highlighting potential public health concerns.
For the energy sector, these findings are particularly relevant. The agricultural industry is a significant consumer of water and energy, and the safe reuse of wastewater can help reduce the sector’s environmental footprint. However, the persistence of ARGs in effluents suggests that current wastewater treatment processes may need further optimization to ensure the safety of reclaimed water.
The presence of multidrug-resistant (MDR) ESBL-E. coli isolates across all wastewater treatment plants is a cause for concern. These isolates exhibited resistance to β-lactams, quinolones, tetracyclines, and sulfonamides, but notably low levels of resistance to last-resort antibiotics were observed. This finding is a double-edged sword, offering a glimmer of hope while also serving as a stark reminder of the ongoing battle against AMR.
As the world grapples with the challenges of water scarcity and antimicrobial resistance, this research offers valuable insights into the safe reuse of wastewater for irrigation. The findings underscore the critical role of tertiary treatments in mitigating AMR risks and highlight the need for further optimization of wastewater treatment processes. As Truchado puts it, “The persistence of ARGs in effluents suggests that current processes require further optimization to ensure the safety of reclaimed water.”
Looking ahead, this research could shape future developments in wastewater treatment technologies, informing the design of more effective and sustainable systems. For the energy sector, the findings underscore the importance of investing in advanced wastewater treatment technologies to support sustainable agriculture and mitigate public health risks. As the world continues to grapple with the challenges of water scarcity and antimicrobial resistance, this research offers a beacon of hope, guiding the way towards a more sustainable and resilient future.