## 1 Introduction  
Recycling and reusing any kind and volume of wastewater (WW) seems to be one of the immediately feasible ways to cope with water scarcity. However, in order to provide safe water for human consumption the disinfection and removal of pollutants are mandatory to avoid undesirable ecological and human health effects. Additionally, wastewater of different quality and origin, surface water, and groundwater can be equally contaminated by microorganisms and chemical compounds, thus always requiring adequate treatment before being considered safe for human consumption [1; 2; 3].  
Despite their low concentration (\(\mu\)g\(\cdot\)L\({}^{-1}\) to ng\(\cdot\)L\({}^{-1}\)), micropollutants, and in particular the emerging pollutants, are objects of great concern because of their toxic, genotoxic, and endocrine disrupting effects. Pharmaceuticals, endocrine disruptors, personal care products, pesticides, industrial dyes, and polycyclic aromatic hydrocarbons contaminate both urban and industrial wastewater since they are released into the environment mostly unchanged in their structure and activity, are resistant to biodegradation, and accumulate in water bodies, crops, and soil [4; 5]. Wastewater treatment plants (WWTPs) are not designed to remove these pollutants; thus, new effective treatments are urgently needed and some of them had already been implemented.  
Chemical disinfection procedures based on chlorine compounds can give rise to disinfection by-products, some of which are carcinogenic in humans and toxic to the environment [6; 7]. Moreover, some pathogenic organisms are not inactivated by these treatments [8; 9] and this limits the reuse of the treated effluents [10].  
For decades, advanced oxidation processes (AOPs) [11], based on fast radical reactions, have been tested as an alternative to, or have been used in combination with, classical WW treatment methods exploiting their disinfectant and oxidative degradation abilities [12; 13; 14; 15; 16; 17; 18]. Among them, ozone has demonstrated an ability to act as an effective parasiticide, germicide, and virucidal agent [19; 20; 21], ensuring the sanitization of several fresh and dry foods, [22; 23; 24; 25; 26; 27] working places, and surfaces. As far as water is concerned, ozone treatment improves its quality, removing the color, smell, and taste at typical disinfection doses [28]; oxidizing inorganic compounds (arsenic, iron, manganese) to form insoluble substances; breaking down quickly without leaving residues or toxic compounds; and enhancing the biodegradability of organic pollutants in wastewater [29]. These features further indicate that ozone is the most appropriate approach in several particular cases [30; 31; 32; 33; 34; 35].  
In various countries, wastewater utilities have installed or are in the process of installing ozone generators to treat secondary effluents [36; 37]. Potable water utilities are doing the same to remove a variety of contaminants in potable water, surface water, and groundwater [1; 19].  
However, wastewater not reaching the treatment plants or drinking water not coming from a suitable potable water utility are a common reality, even in developed countries, requiring effective and flexible solutions.  
The present study aimed to investigate the performance of a self-assembled new prototype of a ozone treatment system which coupled the generator with a recirculation system to create a continuous flow of water and a repeated injection of ozone. The rate of pollutant degradation was determined by HPLC-UV-MS, the variation in toxicity by biotoxicological tests and the sanitization capacity by heterotrophic plate count.  
These results should demonstrate the capability of the system in reducing biotoxicity and in sanitizing biologically contaminated water, indicating that the prototype is a versatile tool for water reclamation, especially in locations without or far from wastewater and potable water utilities.