The aim of this work was to prepare and characterize thin films obtained from weak polyelectrolytes with silver nanoparticles and crosslinked with glutaraldehyde for the development of a new material to be used as a bactericidal agent in the treatment of industrial wastewaters. To evaluate the efficiency of these materials, the thin films were used for the treatment of an industrial wastewater sample. It was observed that, after 360 min of treatment, the thin films which presented the better inhibitory activity against Escherichia coli in the preliminary microbiological tests decreased by up to 93% the total coliforms present originally in the industrial wastewater sample. Considering the ease of application, low environmental impact, and satisfactory inhibiting action, the thin films developed in this work have a great potential to be used as a means of enhancing the removal of coliform bacteria from industrial wastewaters.