Potential of decentralized wastewater treatment to prevent the spread of antibiotic resistance, organic micropollutants, pathogens and viruses

25 April 2022

PRESAGE aims at understanding the integrated behaviour of selected contaminants of emerging concern (CECs) during decentralized wastewater treatment (WWT) in different innovative treatment schemes, based on anaerobic and aerobic compact systems. Source separated domestic sewage, as well as hospital and pharmaceutical industry wastewater will be treated at different demo sites. Effluents suitable for reuse will be produced; their quality will be confirmed through acute and chronic ecotoxicity tests.

An integrated analysis of the behaviour of organic micropollutants (OMPs), pathogens (viruses and bacteria) and antibiotic resistant microorganisms and genes (ARMs/ARGs) will be carried out along different full-scale demo sites (Figure 1).

The project relies strongly on an effective collaboration between researchers from different disciplines who are responsible for different tasks: i) developing innovative technologies, including for disinfection (Figure 2); ii) monitoring OMPs, ARMs and pathogens during the treatments; iii) performing ecotoxicity tests to evaluate the final effluent qualities (Figure 2). This requires a joint selection of the targeted CECs, an agreement on protocols for the analysis of OMPs, extraction procedures for DNA, bacteria isolation protocols and procedures for virus concentrates. Additionally, a detailed planning on samples generated at the demo sites, which will be shipped for the ecotoxicity tests, is necessary.


Figure 1. PRESAGE project concept note and structure (Image source: Francisco Omil).

So, during the first months of the project, different thematic groups were setup to work on such transversal topics. As a result, a short list of common OMPs to be studied at all the demo sites was agreed upon; this list includes: sulfomethoxazol (SMX, sulphonamide), trimethoprim (an antibiotic commonly prescribed in combination with SMX) and ciprofloxazine (fluoroquinolone). The list includes antibiotics that are widely prescribed all around the world and are commonly detected in wastewater effluents. They have also been reported as relevant for the generation of AMRs/ARGs.

Wastewater samples from the different demo sites have been collected and were subjected to high‐throughput analyses to identify a large number (several hundreds) of genes. These results will help to select the target AMR that will be followed throughout the project.

At a technological level, the Anaerobic Membrane Bioreactor for the treatment of black water is already in operation, while the Aerobic Membrane Bioreactor for the treatment of grey water is still being setup (Figure 2A). The pilot plants that combine membrane bioreactors with suspended carriers for biofilm development (Figs. 2C, 2D) are currently being constructed. They will treat hospital effluents starting in July 2022. The anaerobic biofilm reactors (Figs. 2E, 2F) are already in operation at lab-scale, producing first results on their efficiency for the removal of antibiotics. Similarly, the Particle Bed Biocidal Reactor (Figure 2G) is being optimized at lab-scale to minimize risks associated with the release of pathogens and AMR.

Ecotoxicity tests during this first stage will be conducted with a synthetic mixture of selected OMPs to determine acute toxicity by normalized tests (Figure 2H).   



Figure 2. Technologies and methodologies to be optimized and validated in the PRESAGE project (Image source: Francisco Omil).