Enhanced biodegradation of organophosphorus insecticides in industrial wastewater via immobilized Cupriavidus nantongensis X1T

Chlorpyrifos is an important organophosphorus insecticide. It is highly toxic to mammals and can pollute the environment. Cupriavidus nantongensis X1^T can efficiently degrade chlorpyrifos. Immobilization technology can also improve the viability, stability and catalytic ability of bacteria. In this study, strain X1^T was, therefore, captured on various composite immobilized carriers, sodium alginate (SA), diatomite (KLG), chitosan (CTS) and polyvinyl alcohol (PVA). The four types of immobilized beads (SA, SA + KLG, SA + CTS and SA + PVA) could form a slice and honeycomb structure to capture strain X1^T. The results showed that SA + CTS (SC) was an optimal material combination for the immobilization of strain X1^T to degrade chlorpyrifos. Compared with SA-X1^T, after adding CTS, the specific surface area and adsorption capacity for chlorpyrifos were increased 3.4 and 1.7 fold, respectively. SC-X1^T could degrade 96.6% of chlorpyrifos at 20 mg/L within 24 h and the degradation rate constant was 4.8 fold greater than immobilized strain LLBD2, a well-studied chlorpyrifos-degrading strain. The immobilized beads SC-X1^T also showed a more stable and greater degradation ability than X1^T free cells for chlorpyrifos in industrial wastewater. The synergy of adsorption and degradation of immobilized strain X1^T is suitable for in-situ remediation of chlorpyrifos contaminated environment.