Biodegradation of imidacloprid by composting process

Abstract

This work presents the biodegradation of imidacloprid during composting process in a closed reactor. Composting mass was prepared from fresh vegetable waste, tobacco waste, dry leaves, imidacloprid 1.25 mg/kg (dry solids) and bacterial suspension of Pseudomonas aeruginosa FN. The composting process was carried out under forced aeration (0.516 dm3/min/kg) in a column reactor (10 dm3) under adiabatic conditions over 21 days. In a closed reactor system, the intense biodegradation of imidacloprid was during first 7 days when 68% of imidacloprid was degraded. The conversion and rate of biodegradation of imidacloprid in a closed reactor was much higher and faster than in an open pile. Imidacloprid degradation during composting process was described and simulated as first-order process. Degradation constant and half-life of imidacloprid were estimated in a closed reactor (k d = 0.135 ± 0.016 mg/kg/day, t 1/2 = 5.13 days) and in an open pile (k d = 0.025 ± 0.002 mg/kg/day, t 1/2 = 27.88 days).