The removal of diuron from agricultural wastewaters by Trametes versicolor immobilized on pinewood in simple channel reactors

Abstract

The presence of pesticides in agricultural wastewater entails harmful risks to both the environment and public health. In this study, two channel-type bioreactors with Trametes versicolor immobilized on pinewood chips were evaluated in terms of the removal efficiency of diuron from agricultural wastewater under non-sterile conditions. First, both single and successive sorption processes of diuron on pinewood chips were evaluated. The Freundlich model showed the best correlation in the sorption isotherm study (R2 = 0.993; Δq = 5.245), but according to repeated sorption experiments, the Langmuir model (R2 = 0.993; Δq = 5.757) was considered more representative. Equilibrium was reached after approximately 48 h, and the Elovich kinetic model gave the best fit with the experimental data. A packed-bed channel bioreactor (PBCB) was found to be a remarkable alternative able to remove up to 94% diuron from agricultural wastewater during 35 d. However, periodic manual mixing was required to guarantee an aerobic process, and a rotating drum bioreactor (RDB) was subsequently proposed as an enhanced version. The RDB removed up to 61% diuron during 16 d using almost 7 times lower wood dose (152 g wood·L-1) than in the PBCB (1000 g wood·L-1).