Enhanced biodegradation of mixed phenol and sodium salicylate by Pseudomonas putida in membrane contactors

Kinetic studies on the removal of phenol by MBBR from saline wastewater

BACKGROUND

Phenols are chemical compounds which are included in the high priority of pollutants by environmental protection agency (USEPA). The presence of high concentrations of phenols in wastewaters like oil refineries, petrochemical plants, olive oil, pesticide production and oil field operations contain high soluble solids (TDS) and in an olive oil plant, wastewater is acidic, high salty and phenol concentrations are in the range of 0.1- 1%.

METHODS

Kinetic parameters were calculated according to Monod, Modified Stover- Kincannon, Hamoda and Haldane models. The influence of different initial phenol concentrations on the biodegradation rate was performed. The concentrations of phenol varied from 0 to 500 mg/l.

RESULTS

The value of K_i in saline phenolic wastewater in attached growth systems was higher than suspended growth systems that represented a higher phenol inhibition in suspended growth systems. It was obvious that the best model fitting the obtained data are Hamoda model and the Modified Stover-Kincannon model, having highest R² values of 0.991 and 1, respectively. The value of K_i in saline phenolic wastewater in attached growth system was higher than suspended growth systems which represented a higher phenol inhibition in suspended growth systems.

CONCLUSIONS

Hamoda model and the Modified Stover-Kincannon model having highest R2 value of 0.991 and 1, respectively, and also predicting reasonable kinetic coefficient values.

Experimental and kinetic study on the cometabolic biodegradation of phenol and 4-chlorophenol by psychrotrophic Pseudomonas putida LY1

This study investigated the kinetics of phenol and 4-chlorophenol (4-CP) biodegradation by a cold-adapted bacteria, Pseudomonas putida LY1, isolated from Songhua River sediment. The results showed that P. putida LY1 cannot grow on 4-CP as a sole carbon source. P. putida LY1 had the potential to cometabolic biodegrade phenol and 4-CP in a wide range of temperature (varying from 5 to 35 °C) with the optimal temperature around 25 °C. Mixture of phenol and 4-CP were completely removed at two 4-CP concentrations (15 and 40 mg/L) over a wide range of phenol (20-400 mg/L) concentrations, whereby the ratio of 4-CP/biomass (S 2/X) was lower than 0.03. The kinetic models of cometabolic biodegradation of phenol and 4-CP were proposed, considering the growth and nongrowth substrate inhibition. These models successfully simulate the processes of cometabolic degradation of phenol and 4-CP.

Hollow-fiber membrane bioreactor for the treatment of high-strength landfill leachate

Performance assessment of membrane bioreactor (MBR) technology for the treatability of high-strength landfill leachate is relatively limited or lacking. This study examines the feasibility of treating high-strength landfill leachate using a hollow-fiber MBR. For this purpose, a laboratory-scale MBR was constructed and operated to treat leachate with a chemical oxygen demand (COD) of 9000-11,000 mg/l, a 5-day biochemical oxygen demand (BOD5) of 4000-6,000 mg/l, volatile suspended solids (VSS) of 300-500 mg/l, total nitrogen (TN) of 2000-6000 mg/l, and an ammonia-nitrogen (NH3-N) of 1800-4000 mg/l. VSS was used with the BOD and COD data to simulate the biological activity in the activated sludge. Removal efficiencies > 95-99% for BOD5, VSS, TN and NH3-N were attained. The coupled experimental and simulation results contribute in filling a gap in managing high-strength landfill leachate and providing guidelines for corresponding MBR application.

Novel method for determination of phenol degradation kinetics

In this study, we proposed a new method for estimating biokinetic parameters in phenol degradation kinetics. The new method relies on the new formulation of q-S relation where degradation rate q is calculated from the changes of substrate concentration S for each time segment during the course of entire degradation, while in the conventional method q is obtained from the slope of the straight line that is given as substrate concentration changes with time in a semi-logarithmic scale. Thus, this new method provided more data points than the conventional method. The q-S relations obtained from the new method and the conventional method were fitted with three inhibitory kinetic models of Haldane, Yano and Edwards. Simulation of degradation profile with each kinetic model and comparison with the observed profile revealed that the new method offered a better prediction with Edwards model as the best inhibitory model.

A novel 2,3-xylenol-utilizing Pseudomonas isolate capable of degrading multiple phenolic compounds

This work characterized a novel 2,3-xylenol-utilizing Pseudomonas isolate XQ23. From 16S rRNA phylogenetic analysis, XQ23 was found to be a member of the Pseudomonas putida group. Most of its physiological characteristics also shared similarities to P. putida. Phenols were catabolized by the meta-cleavage pathway. The dependence of the specific growth rate on 2,3-xylenol concentration could be well fitted by the Haldane model, with the maximum occurring at the concentration around 180 mg l(-1). Kinetic parameters indicated that XQ23 was sensitive to 2,3-xylenol and had low affinity. Three patterns, i.e. constant, linear decline, and allometric decline, were proposed to describe the biomass yields of phenols during bacterial degradation and XQ23 under 2,3-xylenol culturing conditions followed the allometric pattern. In a mineral-salts medium supplemented with 180 mg l(-1) of 2,3-xylenol as the sole carbon and energy source, over 40% of 2,3-xylenol was turned into CO(2) to provide energy by complete oxidization.

Degradative potential of Stenotrophomonas strain HPC383 having genes homologous to dmp operon

A strain, Stenotrophomonas HPC383 is isolated from effluent treatment plant treating wastewater from pesticide industry; degrades various aromatic compounds (cresols, phenol, catechol, 4methyl-catechol and hydroquinone) and crude oil, as determined through HPLC and GC analysis. Culture HPC383 could degrade (%) various compounds (1 mM) from a mixture: phenol - 99, p-cresol - 100, 4-methylcatechol - 96 and hydroquinone - 43 within 48 h of incubation, whereas it took 7 days to degrade 94% of 0.5% crude oil. Gene locus dmpN, to identify phenol degrading capacity was determined by PCR followed by southern analysis. The sequenced DNA fragment exhibited 99% sequence similarity to phenol hydroxylase gene from Arthrobacter sp. W1 (FJ610336). Amino acid sequence analysis of phenol hydroxylase reveals it to belong to high-Ks (affinity constant) group. Application of HPC383 in bioremediation of aquatic and terrestrial sites contaminated with petrochemical has been suggested.

Growth kinetics and phenol biodegradation of psychrotrophic Pseudomonas putida LY1

This study investigated the growth kinetics of a psychrotroph, Pseudomonas putida LY1, while growing on phenol as a sole carbon and energy source. This bacterium could completely biodegrade 200mg/L phenol across a temperature range from 2.5 to 35 degrees C, with an optimum temperature of 25 degrees C. High initial phenol concentrations (800 mg/ml) were inhibitory to bacterial growth. At lower concentrations of phenol, the growth kinetics correlated well with the Haldane model. The Haldane parameters of psychrotrophic P. putida LY1 were almost within the range reported for other organisms in previous literature. This information on a psychrotrophic organism is of great importance for low temperature bioremediation of contaminated environments.

Degradation of o-chloronitrobenzene as the sole carbon and nitrogen sources by Pseudomonas putida OCNB-1

A bacterial strain that utilized o-chloronitrobenzene (o-CNB) as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology, physiological, and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32 degrees C. At these conditions, the strain degraded 85% of o-CNB at a starting concentration of 1.1 mmol/L in 42 h. o-Chloroaniline was identified as the major metabolite with high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The study showed that o-CNB degradation by Pseudomonas putida OCNB-1 was initiated by aniline dioxyenase, nitrobenzene reductase and catechol-1,2-dioxygenase.