Liquid Two-phase Partitioning Bioreactor Research Articles

Two-Phase Partitioning Bioreactor for the Treatment of Crude Oil- Contaminated Aqueous Solution

A new application of a combined solvent extraction and two-phase biodegradation processes using two-liquid phase partitioning bioreactor (TLPPB) technique was proposed and developed to enhance the cleanup of high concentration of crude oil from aqueous phase using acclimated mixed culture in an anaerobic environment. Silicone oil was used as the organic extractive phase for being a water-immiscible, biocompatible and non-biodegradable. Acclimation, cell growth of mixed cultures, and biodegradation of crude oil in aqueous samples were experimentally studied at 30±2ºC. Anaerobic biodegradation of crude oil was examined at four different initial concentrations of crude oil including 500, 1000, 2000, and 5000 mg/L. Complete removal of crude oil was achieved biphasic bioreactor after 3 weeks compared to 73-82% in the monophasic bioreactor for the same time period.

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Modeling Study of Crude Oil Enhanced Removal in a Two-Liquid Phase Partitioning Bioreactor

AbstractA combined process of solvent extraction and two-phase biodegradation was carried out to remove crude oil from water by mixed cultures, where silicone oil was selected as the organic solvent due to its biocompatibility and non-biodegradability. The crude oil removal and cell growth was experimentally studied. A simple model that combined steady mass transfer equations and dynamic growth kinetics of suspended cells was suggested to follow the entire process. Under the conditions studied, complete removal of crude oil from water was achieved at initial crude oil concentration of 5,000 mg/L. Results revealed that the proposed model satisfactorily described the process as long as crude oil level in the cell medium did not exceed the toxicity limit of suspended cells.

Isolation and characterization of a toxic metal-tolerant Phenanthrene-degrader Sphingobium sp. in a two-liquid-phase partitioning bioreactor (TPPB)

A phenanthrene-degrading strain PHE3, identified as the genus of Sphingobium, was isolated using a two-liquid-phase partitioning bioreactor. More than 96 % of the initial amount (up to 100 mg l−1 silicone oil) of phenanthrene was removed within 77 h by PHE3. Degradation of phenanthrene by PHE3 at pH 7 was also observed in the presence of Cu (II), Zn (II) and Cd (II) ions. Cu (II) showed the highest toxicity to PHE3, followed by Cd (II) and Zn (II). Tolerance to Cu (II) by PHE3 was up to 20 mg l−1 in terms of total aqueous concentration, and up to 40 mg l−1 for both Zn and Cd. Interestingly, 20 mg l−1 of Zn (II) stimulated phenanthrene degradation after 20 h incubation. Its high tolerance to toxic metals and phenanthrene degradation ability of PHE3 highlights its significance in the study of microbial remediation in soils co-polluted by PAHs and metals.

A two liquid phase partitioning bioreactor system for the biodegradation of pyrene: Comparative evaluation and cost–benefit analysis

AbstractBACKGROUND: Biodegradation of pyrene, a novel polycyclic aromatic hydrocarbon (PAH) of environmental concern, was investigated employing a two‐liquid phase partitioning bioreactor (TPPB) using Mycobacterium frederiksbergense. After initial screening of solvents, silicone oil was chosen as the biocompatible and economic solvent for use in this TPPB system with an initial pyrene concentration of 400 mg L−1. The efficiency of the TPPB system developed was also compared with the results of pyrene degradation by the microorganism in slurry phase and surfactant‐aided systems. A cost–benefit analysis comparison of the three systems evaluated in the work further revealed very good potential of the TPPB system in pyrene biodegradation.RESULTS: Using silicone oil as the non‐aqueous phase liquid in the TPPB system, pyrene was found to be completely degraded by M. frederiksbergense within 6 days with a degradation rate of 140 mg L−1 d−1, which was at least seven times more than the values obtained in the slurry phase or surfactant‐aided systems. Further cost–benefit analysis comparison of the three systems revealed TPPB to be the most effective with a minimum cost of $ 0.62 per mg of pyrene degraded.CONCLUSION: Performance of TPPB system, in terms of both efficiency and economics of pyrene degradation by M. frederiksbergense was found to be superior to slurry phase or surfactant aided systems. Copyright © 2010 Society of Chemical Industry

Modelling gas–liquid VOCs transport in two-liquid phase partitioning bioreactors

A mechanistic model capable to accurately describe the mass transport of hexane in a two-liquid phase partitioning bioreactor (TLPB) constructed with silicone oil was developed. This work constitutes the first step in the development of simple and reliable models for the mathematical description of the off-gas treatment of volatile organic contaminants in TLPBs. The model (based on general mass balances and transport equations over off-gas rising bubbles) predicted a negative linear relationship between the fraction of organic phase and the logarithm of the pollutant fraction that remains in the gas phase. The average relative errors of the model predictions were lower than 7%. Under the tested range of operational conditions (organic phase fractions and stirring rates ranging from 5% to 30% and from 100 to 300 rpm, respectively) the maximum hexane fraction transferred from the gas to the liquid (aqueous + organic) phase increased at increasing stirring rates and silicone oil fractions up to 200 rpm and 20%, respectively. In addition, the proposed modelling approach quantified the proximity of the dispersion to thermodynamic equilibrium conditions, predicting thus the degree of mixing in the systems.