Risk Assessment and Risk Management in Managed Aquifer Recharge and Recycled Water Reuse: The Case of Sabadell

• Autores: María Neus Ayuso Gabella
• Directores de la Tesis: Joan Mata-Álvarez (dir. tes.), Miquel Salgot de Marçay (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2015
• Idioma: inglés
• Tribunal Calificador de la Tesis: Xavier Sánchez Vila (presid.), Montserrat Folch Sánchez (secret.), Alvaro Enrique Fernández Escalante (voc.)
• Materias:
  • Ciencias de la tierra y del espacio
    • Hidrología
      • Aguas subterráneas
      • Calidad de las aguas
  • Ciencias tecnológicas
    • Ingeniería y tecnología del medio ambiente
      • Regeneración del agua
• Enlaces
  • Tesis en acceso abierto en:  TDX  Dipòsit Digital de la UB 
• Resumen

  • The increasing practice of water recycling, including or not managed aquifer recharge (MAR), requires to thoroughly assess the risks posed by it in real systems, not only in laboratory and column studies. The present work has been developed in a case study in Sabadell, Spain. For this site, the treated effluent of the Ripoll River WWTP is discharged into the Ripoll River, thus enhancing the natural infiltration to the alluvial aquifer. Pumping of the groundwater induces a riverbed filtration process (RBF), which is one of types of MAR. The recovered water undergoes further post-treatments, including UV, chlorination and sand filtration. After the post-treatments, the water is used for park irrigation and street cleaning. This site was part of the RECLAIM WATER project, supported by the European Commission and devoted to studying MAR and the use of reclaimed water for it in different locations in Europe, as well as in other countries outside Europe. For Sabadell case study, named “RISMAR” in the present work, a risk assessment and a risk management have been developed. In addition, a quantitative microbial risk assessment (QMRA) has been developed too. QMRA is not as usually applied to recycled water schemes as it is to drinking water ones, and even less to MAR. In order to develop the risk assessment, it was necessary to gather data on the site. Most of the data used to develop the present work were generated in the framework of the RECLAIM WATER project, and it included not only basic wastewater and surface water regular parameters and microbiological indicators, but also trace compounds, pathogens and antibiotic resistance genes. Other data were available from public institutions and previous works. The main results of the risk assessment indicate that for the uses considered for the final treated water the risk is low and in some cases medium, with the exception of using the final treated water as drinking water. Currently, this use it is not in place at the site, and it is not expected to be in the near future. The QMRA results additionally indicate that cross-connection, swimming and the immunocompromised population would be in the limit of the acceptable level of risk. Thus, the immunocompromised population should be considered in risk assessments, as the risk for them might be much higher than for the rest of the population. The residual risks that needed to be managed and considered were posed by inorganic compounds, organic compounds, salinity and mobilization of inorganic compounds from the sediments. Another important result of the work is that the RBF and subsurface treatment proved to be very useful in reducing the risks posed by pathogens, nutrients, organic compounds and particulates. In contraposition, other risks appeared, like the mobilization of inorganic compounds from the aquifer. Then, these positive results support the request by many authors of treating MAR as an additional treatment. Finally, a risk management plan has been developed, integrating the results of the risk assessment. For this risk management plan, not only the critical control points are identified, as it is typical for risk managements, but the twelve elements of the framework issued by the Australian Government (NRMMC-EPHC–NHMRC, 2009) have been assessed and developed, thus supporting a robust risk management plan. Emphasis is put in corrective and preventive actions for the system, as well as in defining the critical limits, monitoring program and sampling points. Besides, validation is given the importance it has in order to ensure a proper functioning of the system.