Performance of a continuous stirred tank bioreactor employing an immobilized actinobacteria mixed culture for the removal of organophosphorus pesticides

Abstract

In this study, we evaluated polyurethane foam (PF), volcanic rock (VR), and a modified plastic cap (MPC) as supports for the immobilization of organophosphorus (OP) pesticide-degrading actinobacterial strains. The colonization and activity of four streptomycetes were favoured by PF, which was selected as the carrier to use in a continuous stirred tank bioreactor (CSTR) that can be operated at increasing inflows of a pesticide mixture that contains the insecticides chlorpyrifos (CP) and diazinon (DZ). Our results demonstrate that the CSTR can be operated at flow rates of 10 and 40 mL h −1 with greater than 85% removal of the pesticides in the short term. A significant decrease in the efficiency of CP removal was observed at the highest inflows into the reactor. The CP and DZ loading rates in the bioreactor ranged from 0.44 to 1.68 mg L −1 h −1 and from 0.50 to 2.17 mg L −1 h −1 , respectively. Although the treated wastewater exhibited moderate toxicity for Raphanus sativus, a bioreactor inoculated with a mixed culture formed by Streptomyces spp. strains AC5, AC9, GA11 and ISP13 may provide an effective biotechnological strategy for the reduction of OP pesticide residues produced during agronomic and manufacturing practices and therefore prevent environmental pesticidal pollution.

Treatment of Pesticide-Contaminated Water Using a Selected Fungal Consortium: Study in a Batch and Packed-Bed Bioreactor

“…During the operation of the bioreactor, only occasional destabilizations were observed, which were coincident with the flow rate increases; however, a quick recovery in performance was always observed. This tendency matches the reported results for other pesticides such as malathion and CHL treated in PBR [19,33,38]. In general, ATZ removal in the bioreactor showed a similar trend to that observed in batch mode, with a value that fluctuated by 60% in terms of removal, thus being the least removed of the three pesticides.…”

“…In this study, we used encapsulation in calcium alginate as the model support because this technique is simple, inexpensive, and has been proven to be effective for use in pesticide degradation processes [37]. The immobilization of fungal strains into alginate beads (30% wv −1 ) was effective because of the slightly accelerated degradation of IPR and CHL, perhaps due to the high density of cells immobilized in the support [38]. Therefore, this inoculum concentration was used to implement the operation of the packed bioreactor with the immobilized fungal consortium.…”

“…The performance of a bioreactor for the treatment of wastewater containing pesticides greatly depends on the flow rate, the composition of the inflowing medium, the microbial cell concentration, and the bioreactor's catabolic capabilities, among other factors [16,38]. In this study, the performance of PBR operated in continuous mode was evaluated based on its removal efficiency.…”

Advances in Chemotactic and Non-chemotactic Bioremediation of Water: A Comprehensive Review

“…This immobilized culture was used as inoculum for continuous stirred tank bioreactor with 800 ml working volume. Authors reported 100% removal of pesticides within 72 hours with 50 mg L -1 initial concentration [47]. Fungi are well reported for degradation of pesticides [45].…”