Felipe Gallardo
La Frontera University, Chile
Title: Bioaugmentation of a bio-purifi cation system to improve a mixture of pesticides degradation
Biography
Biography: Felipe Gallardo
Abstract
Repeated application of pesticides in a bio purifi cation system (BPS) developed an active microbial population with the ability to degrade these compounds at high concentrations. We evaluated the degradation of a mixture
of the pesticides atrazine (ATZ), chlorpyrifos (CHL) and iprodione (IPR) in a BPS inoculated with a previously used bio mixture (PUB). Th e BPS was contaminated each 30 days with a commercial mixture of the mentioned pesticides at 50 mg kg-1 each, during the last three years. For degradation assays new bio mixtures (5000 g) were placed in glass deposits (40×25×15 cm) and inoculated with diff erent percentages (v v-1) of PUB (0, 5, 10 and 15% PUB). Deposits were spiked with a mixture of the above-mentioned pesticides at 100 mg kg−1 each, with reapplication each 30 days during 90 days. Th e pesticides dose applied was approximately ten-fold above the recommended field dose, to simulate a pesticide spill on the biomixture. Th e residual pesticides and enzymatic activities of phenoloxidase, dehydrogenase and urease in each BPS were periodically measured before each contamination and,
kinetic parameters were calculated from the degradation data. Main results showed that the degradation of the three pesticides increased as PUB inoculum raises and, no diff erences were observed aft er each replication of the mixture
of pesticides. Th e highest and fastest degradation was observed for IPR pesticide (>95%). In the same way, enzymatic activities were highest as PUB inoculum increased. Th e half-life (t1/2) of ATZ and CHL were signifi cantly decreased as PUB inoculum increased.