Removal of water-based printing inks in a biofilm sequential batch reactor: start-up and kinetic study

Abstract

Abstract Water-based inks face new challenges owing to the generation of polluting effluents throughout their manufacturing process as well as during the cleaning of equipment and printing areas. Appropriate treatments are essential to avoid associated environmental problems resulting from toxicity, impeding the passage of light and diffusion of oxygen in water bodies. This study aims to evaluate the ability of the microbial consortium MJ1, isolated from Mexican soil, to remove four commercial water-based inks, namely magenta (MI), yellow (YI), black (BI), and cyan (CI), in batches and in a 6 L sequential batch reactor. FIA-ESI-FTICR-MS analysis identified pigments Violet 19 and Red 122 in the MI ink, Pigment Yellow 74 in the YI ink, and Phthalocyanine and Pigment Blue 15 in the CI ink. The discoloration of the inks depended on the nutrient concentration in the medium. The performance and kinetic parameters of a sequential batch reactor packed with sterilized volcanic rocks, inoculated with the MJ1 consortium, and supplemented separately with MI, YI, BI, or CI inks at concentrations of 3000, 3000, 3000, and 1500 mg L-1, respectively, were evaluated. The hydraulic retention time showed that most discoloration occurred in the first 3.5 d of treatment. Furthermore, elimination rates of 796.8, 791.1, 601.7, and 223.8 mg L-1d-1 were determined for the MI, YI, BI, and CI inks, respectively. A preliminary structure of the generated metabolites was proposed by comparing the results of biodegradation pathway prediction by the EAWAG-BBD database for Violet 19, Red 122, Yellow 74, Phthalocyanine, and Blue 15 pigments to the FIA-ESI-FTICR-MS analysis from biodegradation experiments. In conclusion, the use of a packed sequencing batch reactor has been shown to be an effective method for the discoloration of various commercial water-based print inks. These findings provide important insights into the bioremediation of inks and the associated environmental problems, highlighting the potential for further research and development in this area.