Disinfection of biologically treated industrial wastewater using montmorillonite/alginate/nanosilver hybrids

Abstract

Different techniques have been developed to eliminate microorganisms from industrial wastewater and improve its final quality for reuse. Among them, the use of silver nanoparticles (AgNPs) anchored onto montmorillonite (MMT) and dispersed in a sodium alginate (ALG) polymeric matrix appears to be a good alternative. In this sense, the aim of this work was to prepare MMT–ALG–AgNPs hybrids and then characterize them using UV–vis spectrophotometry, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, to develop a new bactericidal material for the disinfection of industrial wastewater intended for reuse. The results confirmed the presence of spherical AgNPs anchored onto MMT, which was dispersed in the ALG matrix. The evaluation of the bactericidal potential of the MMT–ALG–AgNPs hybrids was performed by the agar diffusion test using two microorganisms (E. coli and S. aureus). These tests showed the formation of a prominent zone of inhibition for both bacteria. The MMT–ALG–AgNPs hybrids were then used to disinfect industrial wastewater. The results indicated a reduction of up to 98.5% of the total coliforms. For comparison, the industrial wastewater was subjected to UV radiation, which is commonly used in the disinfection of water and wastewater. In this case, the removal of the total coliforms using the MMT–ALG–AgNPs hybrids was slightly higher when compared to the use of UV radiation. This result illustrates the potential of these materials for the disinfection of industrial wastewaters.