Table 2 presents the values for the concentration of silver in the industrial wastewater on both the first use and the reuse of the thin films, after treating with thin film (8 4 4). Total quantification of the silver present in this thin film was conducted to verify the percentage of silver leached during each test. The amount of silver in the thin film before treatment process was 0.058 mg L1. The results in Table 2 show that a greater silver leaching occurred in the reutilization of the thin films than in the first use. This higher leaching occurred because, in the test in which the substrates were reused, the thin film was swollen due to contact with the effluent, probably facilitating this process. Thus, for the
same immersion time of the films in the effluent, the removal of coliform bacteria was greater when the films were reused. As can be observed, the untreated industrial wastewater does not have silver in its composition; in addition, the thin films produced in this work have bactericidal activity against coliform through both the contact with silver and the leaching of silver in the industrial wastewater. This process is evident after 5 min of treatment, during which silver leaching does not occur; in this case, approximately 29% of coliforms were removed in the first use, and 53.5% were removed in the reuse.