The method comprises: mixing an adsorbent reagent (31) with water to produce a water-adsorbent reagent mixture and adsorbing the pollutants in the water; subjecting the water-adsorbent reagent mixture to a liquid-solid separation process and producing treated water (90) and sludge (100); contacting the water or treated water with living aquatic organism (220), where the value of property of the living aquatic organism is correlated to the concentration of the pollutants in the water or treated water; and evaluating the value of the property of the living aquatic organism. The method comprises: mixing an adsorbent reagent (31) with water to produce a water-adsorbent reagent mixture and adsorbing the pollutants in the water; subjecting the water-adsorbent reagent mixture to a liquid-solid separation process and producing treated water (90) and sludge (100); contacting the water or treated water with living aquatic organism (220), where the value of property of the living aquatic organism is correlated to the concentration of the pollutants in the water or treated water; evaluating the value of the property of the living aquatic organism; adjusting the quantity of adsorbent reagent mixed with the water as a function of the value of the property of the living aquatic organism; chemically oxidizing the water during the adsorbing process or upstream of the adsorbing process; injecting the adsorbent reagent into the water to be treated when the value obtained is greater than or equal to a predetermined threshold; and controlling the quality of the treated water produced by determining an information representative of the quality of the treated water as a function of the value resulting from evaluating the value of the property of the living aquatic organism. The quantity of adsorbent reagent mixed with the water is proportional to the value obtained by evaluating the value of the property of the living aquatic organism. The step of adjusting the quantity of adsorbent reagent mixed with the water during the adsorption process is performed as a function of the value obtained by evaluating the value of the property of the living aquatic organism. The property of the living aquatic organism is a fluorescent visual signal emitted by the living aquatic organism. The intensity of the visual signal is quantified and correlated with the concentration of pollutants in the water. The step of evaluating the value of the property of the living aquatic organism is implemented in situ. The living aquatic organism: is a genetically modified aquatic organism; is present in the embryonic state; and belongs to the group comprising fish and amphibians. An independent claim is included for a system for treating water having pollutants.
