CHEMICAL ENGINEERINGTRANSACTIONS Modelling of Biodegradation Kinetics for Binary Mixtures of Substituted Phenols in Sequential Bioreactors (original) (raw)
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Substituted phenols are extensively produced and utilized in chemical industry and therefore they are largely present in wastewater. In this paper we considered phenolic mixtures which are representative of industrial wastewater, usually containing multiple substrates. In these conditions, degradation process is strongly affected by the complex interactions among substrates, which include enhancement, inhibition and co-metabolism so a process model is an useful tool to explore and predict the process evolution. Objective of this work was to formulate a kinetic model for the biodegradation of binary mixtures performed in a sequencing batch reactor (SBR). Two model mixtures were investigated: a 4-nitrophenol (4NP) and 2,4-dimethylphenol (2,4DMP) mixture, and a more recalcitrant mixture of 4NP and 2,4-dichlorophenol (2,4DCP). Kinetic tests were performed at different feed concentrations, with single compounds and mixtures and each biodegradation process was kinetically characterized. H...
Applied Microbiology and Biotechnology, 2008
The objectives of this work were to demonstrate the potential of a two-phase sequencing batch reactor in degrading xenobiotics and to evaluate the kinetic parameters leading to a mathematical model of the system. 4-Nitrophenol (4NP), a typical representative of substituted phenols, was selected as the target xenobiotic; this compound has never been remediated in a two-phase bioreactor before. Partition tests were conducted to determine the most appropriate partitioning solvent, and among the three investigated solvents (1-undecanol, 2-undecanone and oleyl alcohol), 2-undecanone was chosen because of its favourable partition coefficient and its negligible emulsionforming tendencies. Moreover, the selected solvent showed satisfactory biocompatibility characteristics with respect to the biomass, with only minor effects on the intrinsic microbial kinetics. Kinetic tests were then performed in a sequencing batch reactor (2-l volume) operated in both conventional one-and two-phase configurations, with the two-phase system showing a significant improvement in the process kinetics in terms of reduced inhibition and increased maximum removal rate. The obtained kinetic parameters suggest that the two-phase sequencing batch system may find full-scale application, as the maximum removal rate k max (~3 mg 4NP mgVSS −1 day −1) is of the same order of magnitude of heterotrophic bacteria operating in wastewater treatment plants.
Aerobic biodegradation of a mixture of monosubstituted phenols in a sequencing batch reactor
Journal of Hazardous Materials, 2013
A sequencing batch reactor (SBR) was inoculated with p-nitrophenol-degrading activated sludge to biodegrade a mixture of monosubstituted phenols: pnitrophenol (PNP), PNP and o-cresol; and PNP, o-cresol and o-chlorophenol. Settling times were progressively decreased to promote biomass granulation. PNP was completely biodegraded. The PNP and o-cresol mixture was also biodegraded although some transitory accumulation of intermediates occurred (mainly hydroquinone and catechol). o-Chlorophenol was not biodegraded and resulted in inhibition of o-cresol and PNP biodegradation and complete failure of the SBR within a few days. The biomass had very good settling properties when a settling time of 1 min was applied: sludge volume index (SVI 5) below 50 mL g-1 , SVI 5 / SVI 30 ratio of 1 and average particle size of 200 µm.
Modeling the Degradation of Phenol by a mixed microbial culture in a Batch Reactor
Biodegradation of phenol by predominantly Pseudomonas species isolated from a sewage wastewater treatment plant was investigated in batch shake flasks. Phenol with a lower concentration of 100 mg/L was degraded in 10 h and a highest of 800 mg/L in 69 h. The phenol degradation rate was observed to vary largely with the concentrations of phenol used and was found to be less than 10 mg/L/h at both the extremes of the initial concentrations. The degradation kinetics was found follow the three half-order kinetic model with the regression greater than 0.97. The specific substrate utilization rates of the culture at various initial phenol concentrations were fitted to modified substrate inhibition kinetic models of Edward, Haldane, Luong, Han-Levenspiel and Yano-Koga. Among these models the Edward was found to fit the data well with a minimum Root Mean Square error value of 0.0039.
Materials Today: Proceedings, 2016
Phenol and cresols co-exist in real-life industrial wastewater, especially in petrochemical, coking and coke-oven industry. An indigenous mixed microbial culture was collected from effluent treatment plant of a coke oven industry. This culture has been employed to biodegrade bi-substrate mixture of phenol and m-cresol under aerobic batch reactor operation. A 2x2 full factorial design with the two phenolic compounds at two different levels of initial concentration (high and low) was explored to design the biodegradation experiments. The variation of the rate of phenolics biodegradation with individual substrate concentration were also determined. The phenol and m-cresol as substrates were completely utilized after 27 hrs when the solutes are present at low concentrations of 100 mg/L each. But the culture has taken total 66 hrs to biodegrade completely higher initial concentrations i.e. 400 mg/L of each substrate. Sum kinetic model was used to describe the variation in the specific substrate degradation rates by the mixed culture. From the interaction parameters obtained from this model, it has been observed that m-cresol inhibits specific phenol degradation rate to a higher extent than inhibition caused by phenol on m-cresol degradation (I m-cresol, Phenol = 0.966, I Phenol, m-cresol = 0.5, RMSE = 0.0171)
Modelling of phenol biodegradation using mixed microbial cultures and variable initial conditions
Phenol biodegradation using mixed microbial cultures was investigated in batch cultures with variable initial concentration of phenol (180-800 mg/L) and biomass (0.75-1.5 g/L). The experimental data show in particular how cell growth is still observed after phenol exhaustion. This fact made the use of a conventional Haldane model, for which specific growth rate µ = 0 when substrate S = 0, inadequate to describe biomass growth profiles. This was attributed to the effect of metabolic intermediates accumulation during phenol degradation that contributes to the mixed microbial population growth still after phenol removal. Consequently, a new Haldane-based model that explicitly integrates the kinetic of the major intermediate was designed, which showed its efficiency to simulate both phenol and biomass concentration evolution over a wide range of initial conditions.
Water Science & Technology, 2006
This work presents the results of the application of an optimally controlled influent flow rate strategy to biodegrade, in a discontinuous reactor, a mixture of municipal wastewater and different concentrations of phenol when used as a toxic compound model. The influent is fed into the reactor in such a way to obtain the maximal degradation rate avoiding the inhibition of the microorganisms. Such an optimal strategy was able to manage increments of phenol concentrations in the influent up to 7000 mg/L without any problem. It was shown that the optimally controlled influent flow rate strategy is a good and reliable tool when a discontinuous reactor is applied to degrade an industrial wastewater.
Review on Advances in Biodegradation of Phenols: Kinetics, Modelling and Mass Transfer
International journal of research - granthaalayah, 2023
Harmful pollutants like phenol and its derivatives are found in wastewater from a wide range of industries, including oil refining, medicines, coal conversion, chemistry, and petrochemistry. The high concentration, high toxicity, and difficult-to-degrade characteristics of phenols in wastewater pose a serious threat to the environment and to human health. By employing different strains of microorganisms and biocatalysts to create biodegradation procedures of diverse pollutants and a wide spectrum of hazardous compounds, biotechnology has successfully addressed significant environmental challenges. Among various phenols removal techniques, biodegradation is both economical and environmentally friendly. During the study of microbial degradation processes, there is a great deal of interest in the potential for mathematical modelling to forecast microbial growth and degrade harmful or inhibiting environmental pollutants at variable quantities. Such mathematical models are frequently created using aromatic compounds like phenol. The review discusses the following topics: kinetics, modelling, and mass transfer; future scope and directions; diverse microorganisms, bioreactors, the metabolic pathway of phenol, influencing factors, and recent advancements in biological therapy.
Development and validation of a simplified model for the anaerobic degradation of phenol
Water Science & Technology, 2009
The anaerobic treatment of phenolic wastewater has demonstrated to be a suitable biological system, for that reason, a large number of systems have been implemented in a lab/pilot scale, several industrial plants have also been developed. Despite of this, there is a lack of modeling applications within these systems. In order to enhance the anaerobic treatment of this kind of water, a simplified model of 2 populations and 3 reactions was developed and implemented. The parameter calibration and the model validation were carried out with experimental data obtained from an Anaerobic Sequencing Batch Reactor treating phenolic wastewater through two different operational strategies: sequential batches with a co-substrate and sequential fed-batches without a co-substrate. The model predicted the reactors performance accurately for the different experimental conditions tested. Therefore, the theoretical basis of the model is, in general terms, valid, and its utilization to predict the reactors performance or in control purposes is feasible.
International journal of water resources and environmental engineering, 2010
Mixed microbial culture collected from effluent treatment plant of a coke oven industry has been studied for its phenol biodegrading potential under aerobic condition in a batch reactor. The result showed that, after acclimatization, the culture could biodegrade up to 700 mg/l of phenol. The results showed that specific growth rate of microorganisms and specific substrate degradation rate increased up to 300 mg/l of initial phenol concentration and then started decreasing. The biodegradation kinetics is fitted to different substrate inhibition models by MATLAB 7.1 ©. Among all models, Haldane model was best fitted (Root Mean Square Error = 0.0067) for phenol degradation. The different biodegradation constants (K s , K i , S m , µ µ µ µ max , Y X/S , k d) estimated using these models showed good potential of the mixed microbial culture in phenol biodegradation.