Development of a membrane‐aerated biofilm reactor to completely mineralise perchloroethylene in wastewaters

Abstract

The feasibility of perchloroethylene (PCE) biodegradation using hybrid aerobic/anaerobic microcosms was investigated. Four main factors were evaluated in batch studies; the type of the electron donor, the nature of the inoculum, the effect of different concentrations of electron donor, and the effect of addition of different concentrations of oxygen. Results from these studies showed that; glucose was the best electron donor for PCE degradation, serum bottles seeded with acclimated biomass performed better than those seeded with the unacclimated biomass, glucose in excess did not improve PCE degradation, and the addition of pure oxygen significantly enhanced degradation. It was observed that serum bottles with acclimated sludge receiving oxygen achieved complete mineralisation of PCE to ethylene with mineralisation rates of 0.27 mg L −1 mg cells −1 h −1 . Following these results a membrane-aerated biofilm reactor (MABR) was constructed, and the batch degradation of 5.5 mg L −1 of PCE was followed for 44 days and PCE was completely removed from the system. The appearance of intermediate compounds proved that PCE was degraded, but not completely stripped out from the system. Degradation was not complete as some bio-products were still found in the effluent, but there was no accumulation of a particular intermediate compound. The PCE removal rate observed in this MABR was 0.24 mg L −1 h −1 . During the study on the effect of adding different concentrations of oxygen, a mass balance based on chloride in the bottles revealed that, 92-95% of the PCE could be accounted for, while only 60-65% of the PCE fed in the reactor could be accounted for as chloride. The MABR developed here may prove to have considerable potential in treating wastewater containing a variety of refractory organics such as PCE.

Comparison of Planktonic and Biofilm Cultures of Pseudomonas fluorescens DSM 8341 Cells Grown on Fluoroacetate

“…The biodegradation of many chlorinated compounds has been widely reported (5,26,28). However, in spite of the increased use of organofluorine compounds in the past 60 years, there is limited information on their degradation (17).…”

Degradation of diesel oil by immobilized Candida tropicalis and biofilm formed on gravels

“…Most microorganisms that have the ability to degrade xenobiotic compounds have comparatively slow growth rates, and biofilm reactors allow the enrichment of these microorganisms independent of hydraulic retention times (Wobus et al 1995). It has been shown in numerous studies that biofilms are less susceptible than suspended bacteria to changes in environmental conditions such as temperature and pH and the presence of metabolic products and toxic substances (Wobus et al 1995;Ohandja and Stuckey 2006). The high cell concentrations that could be achieved in biofilm systems in combination with high volumetric flow rates could potentially result in high biodegradation rate without the risk of cell washout.…”

Mass transfer in a membrane aerated biofilm

“…Dans le cas d'un réacteur à biofilm aéré sur membrane, de l'oxygène est présent à la base du biofilm sans substrat à consommer. Cette zone est alors propice au développement de la respiration endogène (Casey et al, 2000a) Ce type de biofilm peut aussi être intéressant pour stratifier le biofilm selon une zone anaérobie et une zone aérobie pour la dégradation du perchloro-éthylène par exemple (Ohandja et Stuckey, 2006). 2.…”