Decolorization of Reactive Yellow 174 dye in real textile wastewater by active consortium: experimental factorial design for bioremediation process optimization
Lamia Ayed, N. Ladhari, Sami Achour, Kamel Chaieb
Abstract
Dyes are priority pollutants, commonly found at significant concentrations in textile effluents. The presence of dye stuffs in wastewater can cause severe problems to aquatic life and human beings. Therefore, the removal of dyes from wastewater is important in order to minimize their hazardous effects on the environment. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting cold bifunctional reactive dye namely CI Reactive Yellow 174 (CI RY 174) batch degradation studies using bacterial strains. The most suitable species were Sphingomonas paucimobilis, Pseudomonas putida and Lactobacillus acidophilus. Process parameters were optimized using response surface methodology (RSM) and under the optimum conditions (e.g. inoculum size of 10% (OD600nm = 1), temperature of 35 °C, 150 ppm, and time of 5 days). The maximum COD and color removal efficiencies, when tested with 750 ppm dye using batch reactors were found to be 86% and 90%, respectively. Our results showed that bacteria had a high decolorization capacity. High regression coefficient values (predicted R2 = 83.65%) confirmed that the predicted values were in compliance with the experimental values implying the appropriateness of the employed regression model. The adequacy of the model was validated by different descriptive statistics viz, regression, residual error, F and p values. UV–visible and FTIR spectroscopy analysis confirmed the biodegradation of CI RY 174. Using phytotoxicity endpoints, toxicological studies of CIRY 174 before and after biodegradation were studied. Toxicity assay proved that biodegradation led to detoxification of CIRY 174 dye.