What have we learned from worldwide experiences on the management and treatment of hospital effluent? — An overview and a discussion on perspectives

This study overviews lessons learned from experimental investigations on dedicated treatment systems of hospital effluent carried out worldwide in the last twenty years. It includes 48 peer reviewed papers from 1995 to 2015 assessing the efficacy of different treatment levels (preliminary, primary, secondary and polishing) of hospital wastewater in removing a wide spectrum of pharmaceutical compounds as well as conventional contaminants. Moreover, it highlights the rationale and the reasons for each study: reducing the discharge of micropollutants in surface water, improving existing wastewater treatment technologies and reducing the risk of spread of pathogens causing endemic diseases and finally, it offers a critical analysis of the conclusions and suggestions of each study. The most investigated technologies are membrane bioreactors equipped with ultrafiltration membranes in the secondary step, ozonation followed by activated carbon filtration (in powder and in granules) in the polishing step. Interesting research projects deal with photo-Fenton processes acting as primary treatments to enhance biodegradation before biological treatment, and as a polishing step, thus further reducing micro-contaminant occurrence. Investment and operational costs are also presented and discussed for the different treatment technologies tested worldwide, in particular membrane bioreactors and various advanced oxidation processes. This study also discusses the need for further research to evaluate toxicity resulting from advanced oxidation processes as well as the need to develop an accurate feasibility study that encompasses technical, ecotoxicological and economic aspects to identify the best available treatment in the different situations from a global view point.