Treatment of Fluoroacetate by a Pseudomonas fluorescens Biofilm Grown in Membrane Aerated Biofilm Reactor

Abstract

Fluorinated organic compounds have widespread applications, and their accumulation in the environment is a concern. Biofilm reactors are an effective technology for the treatment of contaminated wastewater, yet almost no research has been conducted on the effectiveness of biofilms for the biodegradation of fluorinated aliphatic compounds. In this paper we describe experiments undertaken to investigate the degradation of fluoroacetate using a membrane aerated biofilm reactor (MABR) by Pseudomonas fluorescens DSM8341. The concentration of fluoroacetate in the medium influenced biofilm structure, with less dense biofilm observed at lower fluoroacetate loading rates. As biofilm thickness increased, oxygen utilization decreased, probably as a consequence of increased resistance to oxygen transfer. Furthermore, most of the biofilm was anaerobic, since oxygen penetration depth was less than 1000 µm. Biofilm performance, in terms of fluoroacetate removal efficiency, was improved by decreasing the fluoroacetate loading rate, however increasing the intramembrane oxygen pressure had little effect on biofilm performance. A mathematical model showed that while fluoroacetate does not penetrate the entire biofilm, the defluorination intermediate metabolite glycolate does, and consequently the biofilm was not carbon limited at the biofilm-membrane interface where oxygen concentrations were highest. The model also showed the accumulation of the free fluoride ion within the biofilm. Overflow metabolism of glycolate was identified to be most likely a result of a combination of oxygen limitation and free fluoride ion inhibition. The study demonstrated the potential of MABR for treating wastewater streams contaminated with organofluorine compounds.

Biocatalytic membrane reactors for the removal of recalcitrant and emerging pollutants from wastewater

“…Fluorinated organics and pharmaceuticals are emerging pollutants and their degradation has been investigated in oxygen-based MBfRs. A Pseudomonas fl uorescens culture removed fl uoroacetate with removal effi ciencies ranging from 61.0% to 91.5% in 72-h tests (Heffernan et al ., 2009 ). The pharmaceuticals sulfamethazine and sulfathiazole were removed with effi ciencies of 77 ± 2% and 87 ± 2%, respectively, at a hydraulic retention time of 3 h in a MBfR fed with pure oxygen (Kim et al ., 2010 ).…”

Factors affecting performance and functional stratification of membrane-aerated biofilms with a counter-diffusion configuration

“…[4][5][6] Due to the bubbleless aeration and high oxygen transfer efficiency, membrane aeration shows additional advantages such as lower operational cost and reduced stripping of odors and volatile pollutants from the wastewater being treated. 7,8 Recent research attempts have been made toward MABR to advance treatment performance, prevention of secondary pollution and low energy consumption. 4,9,10 The MABR biotechnology has been broadly used in the treatment of domestic sewage, 11,12 ammonia-containing wastewater, 11,13 simultaneously remove C and N pollutions, 14,15 volatile pollutant, 9,16 toxic xenobiotics in industrial wastewater.…”

“…4,9,10 The MABR biotechnology has been broadly used in the treatment of domestic sewage, 11,12 ammonia-containing wastewater, 11,13 simultaneously remove C and N pollutions, 14,15 volatile pollutant, 9,16 toxic xenobiotics in industrial wastewater. 4,7,[17][18][19] For example, a hybrid membrane-aerated bioreactor was used to treat acetonitrile (ACN) wastewater, and ACN removal rate, the total organic carbon TOC removal rate and total nitrogen (TN) removal rate reached 98.7, 82.4 and 44.1%, respectively. 9 Although the MABR is an attractive way for high-rate treatment of wastewater, some key problems still exist in engineering applications: (i) because of the limit to the biolm thickness, the biomass amount of membrane-aerated biolm may be constrained.…”

Performance analysis of a pilot-scale membrane aerated biofilm reactor for the treatment of landfill leachate

“…In addition, since the region of active aerobic biofilm growth is close to the membrane where the oxygen is abundant, the bacteria are protected to some degree from the effect of toxic chemicals which might inhibit their growth [12]. The concentration of toxic chemicals such as heavy metals can be reduced by adsorption as they diffuse through the outer layers of the biofilm.…”