Zero-discharge advanced treatment for a SAfe and sustainable urban WAstewater Reuse – SAWARE

Nowadays, water scarcity is a big challenge facing humanity in many places around the world. To solve this problem, municipal wastewater (WW) is thus considered to be an alternative water source for various applications after proper treatment. Nonetheless, urban WWs are increasingly contaminated with organic micropollutants (OMPs) such as biocides and environmental persistent pharmaceutical substances (EPPS). Although their concentration in urban WWs is often very low (= 10 µg/L), their effects can be disastrous because of their potential persistence in the environment, their possible endocrine disrupting effect and their accumulation in biological bodies. These toxic compounds have become a major issue for the Water Utilities (REACH 2006, WFD 2000 and 2012) and in the coming years, legislations in European Union will be tightened with regard to OMPS in municipal WW and to the discharge of these substances. These evolutions are driving the WW treatment to come up with advanced technologies. Current research on possible treatments for waters polluted by bio-recalcitrant compounds is moving towards a coupling of processes, either traditional or more innovative, with a common objective of low energy consumption and high removal efficiency, to promote safe water reuse with a low environmental impact of effluent discharge.
Membrane processes are under development but as membranes are only a separation step, they must be coupled with techniques for the efficient destruction of pollutants and then provide modern hybrid processes that can be used as well at the source of pollution as at a post-treatment step. With this aim in mind, Ozonation (O3) and Peroxone (O3 + H2O2) process are also investigated, as they generate highly active species, hydroxyl radicals. These radicals are able to attack most organic compounds non-selectively with high reaction rate. SAWARE is a project of applied research which objective is to develop an innovative and advanced “integrated membrane and oxidation system” of municipal WW coupling membrane bioreactor (MBR), nanofiltration (NF) and ozonation (O3) for a safe and affordable WW reuse. The main innovation of the SAWARE project lies in the MBR/ O3/ NF/ expected synergistic effect for advanced treatment of secondary effluent containing a cocktail of priority substances targeted by the legislation. MBR has been chosen as secondary treatment as it permits protection of NF and O3 from suspended matter.
The main scientific objectives of the SAWARE project are to monitor the fate of eight priority and representatives substances in this new treatment, to propose the best design of such combined process and to verify the processes efficiency using a smart combination of analytical and toxicity assessments. The innovative approach will be i) to perform toxicity assessments to validate the treatment efficiency and potentiality; ii) to characterize separately biological, nanofiltration and ozonation removal mechanisms with real matrix; iii) to use innovative functionalized ceramic nanofilters resistant to ozone iv) to optimize the coupling MBR/ O3/ NF at pilot scale in order to prove the feasibility of such zero-discharge OMPS process; v) and to evaluate the efficiency and sustainability of the proposed solutions by a global analysis using Life Cycle Analysis and Cost-Benefit Analysis.
This Life Cycle Assessment will put into perspective the benefic effect of SAWARE with the additional functionality that it brings (on site micropollutants treatment, rational use of chemicals…) compared to standard processes (granular and powder activated carbon or combination of tertiary treatments) from an environmental point of view.