Methsnotrophic Biodegradation of Trichloroethylene in a Hollow Fiber Membrane Bioreactor

Biodegradation of Trichloroethlyene (TCE) in a Hollow Fiber Membrane Bioreactor Was Investigated using a Mutant of the Methanotrophic Bacteria, Methylosinus Trichosporium 0B3b. Contaminated Water Flowed through the Lumen (I.e., Fiber Interior), and the Bacteria Circulated through the Shell Side of the Membrane Module and an External Growth Reactor. in Mass Transfer Studies with a Radial Cross-Flow Membrane Module, 78.3-99.9% of the TCE Was Removed from the Lumen at Hydraulic Residence Times of 3-15 Min in the Lumen and the Shell. in Biodegradation Experiments, 80-95% of the TCE Was Removed from the Lumen at Hydraulic Residence Times of 5-9 Min in the Lumen. the TCE Transferred to the Shell Was Rapidly Biodegraded, with Rate Constants Ranging from 0.16 to 0.9 L (Mg of TSS)-1 Day-1. Radiochemical Data Showed that over 75% of the Transferred TCE Was Biodegraded in the Shell, with the Byproducts Being Approximately Equally Divided between Carbon Dioxide and Nonvolatiles. This Study Shows that a Hollow Fiber Membrane Bioreactor System Coupled with the Mutant Strain PP358 of M. Trichosporium 0B3b is a Very Promising Technology for Chlorinated Solvent Biodegradation. © 1995, American Chemical Society. All Rights Reserved

Development of a hollow fiber membrane bioreactor for cometabolic degradation of chlorinated solvents

textThe purpose of this research was to develop the hollow fiber membrane (HFM) bioreactor system for treatment of chlorinated solvents in waste mixtures. This new technology employs a hollow fiber membrane reactor to separate chlorinated solvents from water or air with subsequent cometabolic biodegradation using a mutant methanotrophic microorganism, Methylosinus trichosporium OB3b PP358. Research objectives included demonstrating successful performance of the HFM bioreactor system for the treatment of trichloroethylene (TCE) contaminated water and air, increasing process efficiency for cost competitiveness with conventional technologies, extending HFM bioreactor studies to chlorinated solvent mixtures, and developing a system design strategy. HFM bioreactor demonstration experiments evaluated various process configurations, flow rates, and influent TCE concentrations. In TCE viii contaminated water experiments, mass transfer coefficients as large as 2.7×10-2 cm/min were estimated and the system was able to sustain an average first-order degradation rate constant of 0.57 L mg TSS-1 d-1 for 500 hours. While configuring the system with chlorinated solvents flowing through the HFM lumen and microorganisms flowing through the HFM shell was preferred for aqueous experiments, air treatment experiments required switching the flows because water vapor mass transfer resulted in water clogged fiber lumen. Following the demonstration experiments, shorter HFM hydraulic residence times between 0.16 and 0.57 minutes were investigated. A tradeoff between providing sufficient oxygenation and methanol stripping in the chemostat was observed. A new process decision variable, specific transformation was defined and values as large as 38.5 µg TCE/mg TSS were sustainable for TCE treatment. In HFM bioreactor experiments with a mixture of TCE and chloroform (CF), large TCE first-order degradation rate constants between 0.75 L mg TSS-1 d-1 and 1.08 L mg TSS-1 d-1 indicated that the addition of CF did not affect TCE degradation. CF mass transfer coefficients were approximately 10% less than TCE coefficients and the average CF degradation rate constant was 0.32 that of TCE. Computer models of mass transfer and biodegradation in the system were constructed and validated with experimental data. A modeling analysis was then conducted on the important decision variables and parameters and the results were used to develop a system design strategy.The purpose of this research was to develop the hollow fiber membrane (HFM) bioreactor system for treatment of chlorinated solvents in waste mixtures. This new technology employs a hollow fiber membrane reactor to separate chlorinated solvents from water or air with subsequent cometabolic biodegradation using a mutant methanotrophic microorganism, Methylosinus trichosporium OB3b PP358. Research objectives included demonstrating successful performance of the HFM bioreactor system for the treatment of trichloroethylene (TCE) contaminated water and air, increasing process efficiency for cost competitiveness with conventional technologies, extending HFM bioreactor studies to chlorinated solvent mixtures, and developing a system design strategy. HFM bioreactor demonstration experiments evaluated various process configurations, flow rates, and influent TCE concentrations. In TCE viii contaminated water experiments, mass transfer coefficients as large as 2.7×10-2 cm/min were estimated and the system was able to sustain an average first-order degradation rate constant of 0.57 L mg TSS-1 d-1 for 500 hours. While configuring the system with chlorinated solvents flowing through the HFM lumen and microorganisms flowing through the HFM shell was preferred for aqueous experiments, air treatment experiments required switching the flows because water vapor mass transfer resulted in water clogged fiber lumen. Following the demonstration experiments, shorter HFM hydraulic residence times between 0.16 and 0.57 minutes were investigated. A tradeoff between providing sufficient oxygenation and methanol stripping in the chemostat was observed. A new process decision variable, specific transformation was defined and values as large as 38.5 µg TCE/mg TSS were sustainable for TCE treatment. In HFM bioreactor experiments with a mixture of TCE and chloroform (CF), large TCE first-order degradation rate constants between 0.75 L mg TSS-1 d-1 and 1.08 L mg TSS-1 d-1 indicated that the addition of CF did not affect TCE degradation. CF mass transfer coefficients were approximately 10% less than TCE coefficients and the average CF degradation rate constant was 0.32 that of TCE. Computer models of mass transfer and biodegradation in the system were constructed and validated with experimental data. A modeling analysis was then conducted on the important decision variables and parameters and the results were used to develop a system design strategy.Civil, Architectural, and Environmental Engineerin

Monochloramine-Sensitive Amperometric Microelectrode: Optimization Of Gold, Platinum, And Carbon Fiber Sensing Materials For Removal Of Dissolved Oxygen Interference

Monochloramine electrochemical determination in an aqueous system using newly fabricated gold and platinum microelectrodes was investigated to optimize sensor operation and to eliminate dissolved oxygen (DO) interference during monochloramine measurements. Carbon fiber microelectrodes were also compared for reference purposes. Gold and platinum microelectrodes exhibited no oxygen interference during monochloramine measurement and provided a linear relationship when operated at +150 and +300 mV vs. Ag/AgCl over a wide concentration range (0–4.2 mg Cl2/L), respectively. The carbon fiber microelectrode with 7-μm tip diameter was not sufficiently sensitive to monochloramine concentrations for detailed study. The baseline signal of both gold and platinum microelectrodes (i.e., signal without monochloramine) was near zero. With the same geometric tip diameter (20-μm tip diameter), gold microelectrodes resulted in better amperometric electrode response to monochloramine than platinum microelectrodes; gold microelectrodes had a higher sensitivity (52 ± 0.7 vs. 18 ± 0.07 pA/[mg Cl2/L]) and lower detection limit (0.12 ± 0.013 vs. 0.33 ± 0.10 mg Cl2/L), resulting in gold as the preferred microelectrode material. The developed gold microelectrode will allow accurate in situ monochloramine determination in biofilm while eliminating the confounding effects of oxygen interference

Three-Dimensional Free Chlorine And Monochloramine Biofilm Penetration: Correlating Penetration With Biofilm Activity And Viability

Disinfectant biofilm penetration and its effect on biofilm aerobic activity and viability are still unclear. In this study, free chlorine and monochloramine were applied until full biofilm penetration occurred, and their effects on biofilm aerobic activity and viability were investigated in three dimensions throughout the entire biofilm depth, extending previous work where viability analysis was limited to the upper biofilm (50 μm depth), free chlorine penetration did not reach completion, and only one-dimensional (depth) profiles were obtained. The free chlorine and monochloramine biofilm concentration profiles were correlated spatially and temporally with aerobic microbial activity and cell-membrane integrity based viability using a combination of (1) microelectrode measurements for disinfectant penetration and (2) LIVE/DEAD BacLight staining, cryo-cross-sectioning, and confocal micrographs analysis for viability measurements throughout the entire biofilm depth. Compared to monochloramine, free chlorine penetration (1) was slower, (2) led to a greater decrease in biofilm thickness from sloughing, and (3) corresponded directly with a viability decrease. In addition, biofilm heterogeneity led to minor differences in either disinfectant\u27s biofilm penetration, and prior biofilm exposure to monochloramine provided little impact to subsequent free chlorine biofilm penetration

Amperometric Carbon Fiber Nitrite Microsensor For In Situ Biofilm Monitoring

A highly selective needle type solid state amperometric nitrite microsensor based on direct nitrite oxidation on carbon fiber was developed using a simplified fabrication method. The microsensor\u27s tip diameter was approximately 7 μm (14 μm spatial resolution). At an applied potential of +1.2 V vs. Ag/AgCl, the microsensor exhibited a linear nitrite response from 0 to 25 mg N L-1, a 0.02 mg N L-1 (1.3 μM) limit of detection, and a fast response (\u3c5 s). There was minimal interference with less than 3% of electrode response changes from major chemicals of interest in drinking water and wastewater systems [oxygen, ammonium, monochloramine, nitrate, sodium bicarbonate (alkalinity), chloride, sulfate, and acetate]. Hydrogen ion (pH) affected nitrite measurement by shifting the baseline response, translating into an approximate change of 0.24 mg N L-1 nitrite per 1 pH unit change. Depending on the conditions (e.g., pH, alkalinity, nitrite concentration), pH may need to be taken into account during nitrite measurement. The developed carbon fiber nitrite microsensor successfully measured nitrite in a nitrifying biofilm and is applicable for in situ analysis in other micro-environments (e.g., microbial mats and sediments)

Determination of the Effects of Medium Composition on the Monochloramine Disinfection Kinetics of Nitrosomonas europaea by the Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods ▿

Various medium compositions (phosphate, 1 to 50 mM; ionic strength, 2.8 to 150 meq/liter) significantly affected Nitrosomonas europaea monochloramine disinfection kinetics, as determined by the Live/Dead BacLight (LD) and propidium monoazide quantitative PCR (PMA-qPCR) methods (lag coefficient, 37 to 490 [LD] and 91 to 490 [PMA-qPCR] mg·min/liter; Chick-Watson rate constant, 4.0 × 10−3 to 9.3 × 10−3 [LD] and 1.6 × 10−3 to 9.6 × 10−3 [PMA-qPCR] liter/mg·min). Two competing effects may account for the variation in disinfection kinetic parameters: (i) increasing kinetics (disinfection rate constant [k] increased, lag coefficient [b] decreased) with increasing phosphate concentration and (ii) decreasing kinetics (k decreased, b increased) with increasing ionic strength. The results support development of a standard medium for evaluating disinfection kinetics in drinking water

Monochloramine Disinfection Kinetics of Nitrosomonas europaea by Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods▿

Monochloramine disinfection kinetics were determined for the pure-culture ammonia-oxidizing bacterium Nitrosomonas europaea (ATCC 19718) by two culture-independent methods, namely, Live/Dead BacLight (LD) and propidium monoazide quantitative PCR (PMA-qPCR). Both methods were first verified with mixtures of heat-killed (nonviable) and non-heat-killed (viable) cells before a series of batch disinfection experiments with stationary-phase cultures (batch grown for 7 days) at pH 8.0, 25°C, and 5, 10, and 20 mg Cl2/liter monochloramine. Two data sets were generated based on the viability method used, either (i) LD or (ii) PMA-qPCR. These two data sets were used to estimate kinetic parameters for the delayed Chick-Watson disinfection model through a Bayesian analysis implemented in WinBUGS. This analysis provided parameter estimates of 490 mg Cl2-min/liter for the lag coefficient (b) and 1.6 × 10−3 to 4.0 × 10−3 liter/mg Cl2-min for the Chick-Watson disinfection rate constant (k). While estimates of b were similar for both data sets, the LD data set resulted in a greater k estimate than that obtained with the PMA-qPCR data set, implying that the PMA-qPCR viability measure was more conservative than LD. For N. europaea, the lag phase was not previously reported for culture-independent methods and may have implications for nitrification in drinking water distribution systems. This is the first published application of a PMA-qPCR method for disinfection kinetic model parameter estimation as well as its application to N. europaea or monochloramine. Ultimately, this PMA-qPCR method will allow evaluation of monochloramine disinfection kinetics for mixed-culture bacteria in drinking water distribution systems

Three-Dimensional Free Chlorine and Monochloramine Biofilm Penetration: Correlating Penetration with Biofilm Activity and Viability

Disinfectant biofilm penetration and its effect on biofilm aerobic activity and viability are still unclear. In this study, free chlorine and monochloramine were applied until full biofilm penetration occurred, and their effects on biofilm aerobic activity and viability were investigated in three dimensions throughout the entire biofilm depth, extending previous work where viability analysis was limited to the upper biofilm (50 μm depth), free chlorine penetration did not reach completion, and only one-dimensional (depth) profiles were obtained. The free chlorine and monochloramine biofilm concentration profiles were correlated spatially and temporally with aerobic microbial activity and cell-membrane integrity based viability using a combination of (1) microelectrode measurements for disinfectant penetration and (2) LIVE/DEAD BacLight staining, cryo-cross-sectioning, and confocal micrographs analysis for viability measurements throughout the entire biofilm depth. Compared to monochloramine, free chlorine penetration (1) was slower, (2) led to a greater decrease in biofilm thickness from sloughing, and (3) corresponded directly with a viability decrease. In addition, biofilm heterogeneity led to minor differences in either disinfectant’s biofilm penetration, and prior biofilm exposure to monochloramine provided little impact to subsequent free chlorine biofilm penetration