Synergistic treatment of textile wastewaters using spent diatomaceous earth loaded with laccases: A cost-effective and eco-friendly approach

Abstract

Biosorption and enzymatic biodegradation are well-known methods for the removal/elimination of several pollutants from the environment. These techniques are usually evaluated individually; however, biosorption coupled with enzymatic biodegradation may be a cheap and promising technology for treating industrial wastewater. In this study, laccases from Trametes versicolor were immobilized on spent diatomaceous earth from brewing filtration (SDE) as a biosorbent previously functionalized with 3-aminopropyltriethoxysilane (APTES). A three-level factorial design was used to optimize the immobilization process. The biosorbent coupled with enzymes (SDE-LA) and without enzymes (SDE-S), as well as free laccases (LA), were applied for the treatment of real textile effluent. Enzyme immobilization on SDE increased pH and thermal and storage stability. SDE-LA was more effective in the removal of chemical oxygen demand from the raw textile effluent (66.2 %) than SDE-S and LA (59.0 % and 14.0 %, respectively). Effluent color and toxicity were also significantly reduced by the treatment with SDE-LA. Overall, laccase immobilized on SDE offers a cost-effective and sustainable alternative for treating/polishing textile wastewaters. This combined process of enzymatic action and biosorption can decrease pollutant loading and toxicity of industrial effluents, allowing their safer disposal in water bodies.