Significantly enhanced biodegradation of profenofos by Cupriavidus nantongensis X1 mediated by walnut shell biochar.

The feasibility of using walnut shell biochar to mediate biodegradation of Cupriavidus nantongensis X1 for profenofos was investigated. The results of scanning electron microscopy, classical DLVO theory and Fourier transform infrared spectroscopy indicated that strain X1 was stably immobilized on biochar by pore filling, van der Waals attraction, and hydrogen bonding. Profenofos degradation experiments showed that strain X1 immobilized on biochar significantly decomposed profenofos (shortened the half-life by 5.2 folds) by promoting the expression of the degradation gene opdB and the proliferation of strain X1. The immobilized X1 showed stronger degradation ability than the free X1 at higher initial concentration, lower temperature and pH. The immobilized X1 could maintain 83% of removal efficiency for profenofos after 6 reuse cycles in paddy water. Thus, X1 immobilized using walnut shell biochar as a carrier could be practically applied to biodegradation of organophosphorus pesticides present in agricultural water.