Biodegradation of carbofuran in sequencing batch reactor augmented with immobilised Burkholderia cepacia PCL3 on corncob

Abstract

The performance of sequencing batch reactors (SBRs) augmented with immobilised Burkholderia cepacia PCL3 on corncob for biodegradation of carbofuran in basal salt medium (BSM) was studied. A 2.0-L SBR with a working volume of 1.5 L was operated for a total cycle of 48 h, consisting of 1.0 h fill phase, 46 h react phase and 1.0 h decant phase. The initial pH of the feed medium was 7.0. Air was fed into the reactor at a controlled flow rate of 600 mL·min −1. The effect of hydraulic retention time (HRT) (14 to 6 days) on carbofuran-degradation efficiency was investigated at a carbofuran concentration in the feed medium of 20 mg·L −1. The shortest HRT resulting in complete degradation of carbofuran was 8 days. At 75% of the optimum HRT (6 days), the effects of biostimulation using organic amendments, i.e. molasses, cassava pulp, rice bran and spent yeast, and the effect of carbofuran concentration in the feed medium (20–80 mg·L −1) were investigated. The optimum conditions for SBRs were an initial carbofuran concentration of 40 mg·L −1 and 0.1 g·L −1 of rice bran as a biostimulated amendment. Complete degradation of carbofuran with a first-order kinetic constant (k 1) of 0.044 h−1 was achieved under these optimum conditions.