Evaluation of Two Operational Regimes: Fed-Batch and Continuous for the Removal of Pharmaceuticals in a Fungal Stirred Tank Reactor

Abstract

Two operational conditions were evaluated to maximize the removal of three anti-inflammatory drugs (diclofenac, ibuprofen and naproxen) and an antiepileptic (carbamazepine) in a stirred tank reactor (STR) operating with free pellets of Phanerochaete chrysosporium. First, the bioreactor was operated in a fed-batch mode (stage I) for 26 days and thereafter changed to continuous mode until day 70 (stage II). Time-course degradation experiments were carried out at days 0, 4, 7, 14 and 20 in order to compare the effect of the culture age on the degradation of the target compounds. The results showed that during stage I the fungus was able to completely remove the three anti-inflammatory drugs meanwhile only partial removal was attained for carbamazepine, between 30 % and 63 %. The maximum removal percentages were obtained on day 20, indicating that the culture age has an influence on the degradation efficiency. When the reactor operation was changed to a continuous feeding, the removal of the three anti-inflammatory drugs decreased until percentages in a range between 17 % up to 95 %; whereas, a recalcitrant compound such as carbamazepine achieved high removal percentage during this stage in comparison with the previous stage (93 % vs. 63 %).