A study on the decolorization of methylene blue by Spirodela polyrrhiza: experimentation and modeling

Abstract

Phytoremediation is a cutting-edge technology applied for the purpose of biological treatment of contaminated soil, water and air. We studied the Spirodela polyrrhiza-assisted removal of methylene blue (MB), and then assessed the effect of dye concentration, pH, plant weight and exposure duration on pollutant elimination in a 7 day time span. Response surface methodology (RSM) was used to design the experiments on a daily sampling basis. The statistical analysis of data shows a promising capability of Spirodela polyrrhiza for bioremediation. The percentage removal of methylene blue in some samples was approximately 90–95%. Results show that the duckweed-aided phytoremediation is highly effective when experiments are run in low concentration of methylene blue, pH of 6–7, and high plant weight. We then came up with an artificial neural network (ANN) model to simulate the dye removal process and analyzed the sensitivity of the system towards various factors. It turned out that the exposure time is the most important factor in the phytoremediation of methylene blue by Spirodela polyrrhiza.