Biodegradation Of P-cresol Research Articles

Assessment of enhanced p-cresol biodegradation by encapsulating pre-immobilised Serratia marcescens strain HL 1 on tea waste biochar into polyvinyl alcohol/sodium alginate matrix

In this study, the potential microorganism was isolated from activated sludge to degrade the p-cresol from wastewater. The isolated species (i.e., Serratia marcescens strain ΗL 1) was identified using a 16 S rRNA gene sequencing technique. Microorganism was immobilized into 1% (w/v) tea waste biochar and encapsulated into polyvinyl alcohol (PVA)/sodium alginate (SA) matrix to save the pure species from contaminant and able to sustain under high loading concentration. The maximum biodegradation efficiency was found to be 86.1 ± 2.0% of p-cresol by using PVA/SA (pre-immobilized (PI) (1%) biochar into PVA/SA) matrix which is much higher than the free cell (42.4 ± 0.7%) and immobilized system (73.8 ± 1.0). The % biodegradation of p-cresol was reduced from 86.1 ± 2.0–80.2 ± 1.4% after the fourth cycle. The matrix's surface morphology and the functional group were analysed by SEМ and FTIR, respectively. Monod and Andrew-Haldane model was used to identify biokinetic parameters. This research work revealed that an innovative PI(1%)biochar@PVA/SA matrix would be useful for the bioremediation of p-cresol. The main metabolic by-product obtained were 4-hydroxybenzoylalcohal (m/z = 124), 4-hydroxybenzoic acid (m/z = 138), maleic acid (m/z = 116) and acetaldehyde (m/z = 29)

Construction and performance assessment of Recirculating packed bed biofilm reactor (RPBBR) for effective biodegradation of p-cresol from wastewater

Wastewater containing excess phenolic compounds is considered a major environmental concern due to its adverse impacts on the ecosystem. In this work, an effort has been given to treat the p-cresol from wastewater using Recirculating Packed Bed Biofilm Reactor (RPBBR). The process parameters, namely inoculum dose, pH, and NaCl (w/v) concentration were optimized to enhance the specific growth and obtained to be 14 ml, 7.0, and 1% NaCl (w/100 ml), respectively. Maximum p-cresol removal efficiency of 99.36±0.2% was achieved at 100 mg L−1 of p-cresol. First-order rate constants were found to be 0.70 day−1 and 0.96 day−1 for batch and continuous mode, respectively. The intermediates were analysed using FT-IR and GC–MS analysis. Pseudomonas fluorescens was used to assess bacterial toxicity and observed that the toxicity was reduced in case of treated wastewater. Finally, the performance of continuous RPBBR was better than the batch mode.

Biodegradation of p-cresol by Serratia marcescens strain HL 1 in batch system: Process optimization, growth kinetic study, phytotoxicity and chlorophyll assessment

The batch experiment was performed for biodegradation of p-cresol from synthetic wastewater using an isolated gram-negative bacterial strain (i.e., Serratia marcescens strain HL 1 (EU371058)). Biodegradation rate affecting parameters such as pH (5.0–10), p-cresol concentration (20–100 mg·L−1), and retention time (24–72 h) were optimized. The maximum degradation (86.32 %) of p-cresol was obtained at an initial concentration of 60 mg·L−1, pH of 7.5, and retention time of 48 h. Based on Haldane model, maximum specific growth (μmax) of the cell was 0.2 h−1, and inhabitation constant (KI) of substrate was 76 mg·L−1. FTIR was used to identify the available functional group in biodegraded p-cresol solution. Conclusively, it was observed that a first-order model could accurately predict reaction kinetics. The rate constant values for the first-order was 0.002 L g VSS−1 h−1. Phytotoxicity and chlorophyll were also investigated.

Integrated process approach for degradation of p-cresol pollutant under photocatalytic reactor using activated carbon/TiO2 nanocomposite: application in wastewater treatment.

Over the years, biodegradation has been an effective technique for waste water treatment; however, it has its own limitations. In order to achieve a higher degradation efficacy, integrated processes are being focus in this area. Therefore, the present study is targeted towards the coupling of biodegradation and photocatalytic degradation of p-cresol. The biodegradation of p-cresol was performed via lab isolate Serratia marcescens ABHI001. The obtained results confirmed that ~85% degradation of p-cresol was accomplished using Serratia marcescens ABHI001 strain in 18 h. Consequently, degradation of remaining residue (remaining p-cresol concentration initially used) was also examined in a batch reactor using activated carbon-TiO2 nanocomposite (AC/TiO2-NC) as a catalyst under the exposure of UV radiation. The AC/TiO2-NC was processed via sol-gel technique and characterized by various techniques, namely Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FT-IR). The investigation allowed p-cresol degradation further augment up to ~96% with the help of spectrophotometer trailed by high performance liquid chromatography (HPLC). This study demonstrates that integrated process (biodegradation-photodegradation) is the cost-effective bioremediation process to overcome such kinds of pollutant issues.

Intensified phenol and p-cresol biodegradation for wastewater treatment in countercurrent packed-bed column bioreactors

An intensified biodegradation process in packed-bed column bioreactors (PBCB) with microbial cells attached to packing/micro-particles surface was proposed and simulated via a dynamic 3D model with continuity, momentum, and species (comprising biomicro-particles) balance equations in liquid/gas, accumulation of biomicro-particles in packed-bed, diffusion and enzymatic reaction within biofilm and liquid film. Phenol and phenol/p-cresol biological removal by Pseudomonas putida was chosen to discuss the enhanced biodegradation efficiency. The biodegradation in single/dual-substrate systems is significantly upgraded as biomass loading on micro-particles surface increases. Microbial cells addition to the surface of micro-particles is more efficient when the foremost extent of biomass is attached to packing via large biofilms with increased resistance to mass transfer, at low phenol concentrations and liquid velocities. These intensified biodegradation systems aim at maximizing the mass transfer in PBCB for treatment of wastewater having high phenols concentration, without reducing the residence time of liquid or diluting the effluent.

Metabolic profile analysis and kinetics of p-cresol biodegradation by an indigenous Pseudomonas citronellolis NS1 isolated from coke oven wastewater

A p-cresol degrading bacterial strain was isolated from coke oven wastewater of an iron and steel plant industry. The isolated strain was identified as Pseudomonas citronellolis NS1 by 16S rRNA gene sequencing method. The isolated Pseudomonas species could degrade 1200 mg l−1 of p-cresol completely in 40 h. Further, at 1200 mg l−1 of initial p-cresol more than 95.4% TOC and 98.5% toxicity removal were also achieved by the microbial culture. The metabolic pathway of the Pseudomonas species was investigated using HPLC, UV visible spectra, FT-IR and GC–MS analysis. The major metabolic intermediate products identified in the bacterial culture were 4-methyl catechol, protocatechuic acid, 3-oxadipic acid, 4- carboxy muconolactone, 2-hydroxy muconicsemialdehyde and maleic acid. Based on the identified metabolic intermediate products, a tentative new meta-cleavage 3-oxoadipate pathway has been proposed. The biodegradation of p-cresol by the culture followed first order kinetic. The biokinetic parameters associated with biodegradation of p-cresol have been estimated as follow; μ = 0.353 h−1, Ksi = 464 mg l−1, Ks = 99.5 mg l−1. It was observed that, when the initial concentrations of p-cresol exceeded more than 1000 mg l−1, about 70% of the total substrate carbon was utilized towards microbial maintenance energy.

Optimization of p-cresol biodegradation using novel bacterial strains isolated from petroleum hydrocarbon fallout

Two potential p-cresol degrading bacterial strains were isolated from petroleum refinery wastewater and identified as Stenotrophomonas sp. (MF004205) strain DBK3 and Bacillus sp. (MF004206) strain DBK4 based on 16S rDNA gene sequencing. While DBK4 was able to utilize p-cresol up to 500 mg L−1 in about 2 days, isolated DBK3 restricted its growth till 600 mg L−1 initial p-Cresol concentration. Further studies were carried out using strain DBK3, which utilized p-cresol as the sole source of carbon. Growth kinetic studies were conducted to determine optimal environmental conditions for growth and biodegradation of p-cresol. Degradation of p-cresol at various preliminary concentrations were also studied at their optimum physiological conditions. 100 mg L−1 p-cresol was found to be the optimal pollutant concentration for growth whereas the ideal temperature and pH for growth and degradation were found to be 37 °C and 7.0 respectively. Microbial growth was monitored spectrophotometrically while residual p-cresol was measured via High Performance Liquid Chromatography (HPLC). Various growth kinetic parameters were estimated by fitting the experimental data to several established substrate inhibition kinetic models by non-linear regression analysis via MATLAB R2017b. The best fit was achieved using Haldane’s kinetic model (maximum growth rate, μmax = 0.1160 h−1 and inhibition constant, KI = 387 mg L−1). The experimental growth kinetic data also fitted reasonably well with Aiba, Yano and Webb model.

Analytical study of effective biodegradation of p-cresol using Serratia marcescens ABHI001: application in bioremediation.

This study evaluated the capability of Serratia marcescens ABHI001 to effectively degrade p-cresol through different techniques. The molecular identity of the laboratory isolate S. marcescens ABHI001 was confirmed through the 16S ribosomal DNA gene pattern, and its morphological features were investigated through field-emission scanning electron microscopy. In addition, the degradation behavior of the isolate for cresol was verified using several techniques, including UV-visible spectroscopy, followed by high-performance liquid chromatography (HPLC), gas chromatography, and Fourier transform infrared spectroscopy. The maximum degradation percentage of 85% for p-cresol could be achieved after 18h of incubation with S. marcescens ABHI001. The formation of p-hydroxybenzaldehyde, p-hydroxybenzoate, and protocatechuate metabolites was confirmed through HPLC. The study results indicate that S. marcescens ABHI001 may have applications in the bioremediation of organic pollutants, such as p-cresol.

Newly isolated alkalophilic Advenella species bioaugmented in activated sludge for high p-cresol removal

In this work, an alkalophilic bacterium (LVX-4) capable of using p-cresol as sole source of carbon and energy was screened and isolated from soil polluted by used oil. Phylogenetic (16S rRNA) and phenotypic characterization using Biolog GN microplates and API 20NE strips indicated that LVX-4 strain is a new Advenella species. It showed both the capability to degrade of p-cresol at high concentrations (750 mg/L) and to use p-cresol for growth in a pH from 7 to 10, although the optimum pH was 9. Moreover bioaugmentation of activated sludge with this strain lead to the complete removal of p-cresol in less than 100 h. This is the first study that shows the potential of Advenella sp. to be bioaugmented in activated sludge system for p-cresol biodegradation.

Biodegradation of p-cresol by Pseudomonas spp.

Phenols are toxic to several biochemical reactions. However, biological transformation of phenols to nontoxic entities exists in specialized microbes, owing to enzymatic potential involving enzymes of aromatic catabolic pathways. In this study, a series of experiments were performed to examine the effects of the mineral medium composition and the pH on p-cresol removal. In this purpose, p-cresol biodegradation was carried out in a batch reactor containing mixed bacteria; the temperature (30°C), the stirring velocity (200 rpm), the KH2PO4 concentration (1.5 g/L), the K2HPO4 concentration (2 g/L), and p-cresol concentration (100 mg/L) were kept constants. The initial pH was varied in the range 5–9 and the mineral components were tested in the following concentration ranges: 0–2 g/L for Nitrogen sources (NH4Cl, KNO3, and NH4NO3), 0–0.5 g/L for NaCl, and 0–0.2 g/L for MgSO4. Their effects on p-cresol biodegradation and specific growth rate were examined. The shorter biodegradation time of p-cresol was 30.5 h for NH4Cl, NaCl, and MgSO4 concentrations of 1, 0.3, and 0.1 g/L, respectively. Maximum specific growth rate (0.34 h−1) and total p-cresol removal were recorded for an optimal pH value of 8.

Biological treatment of wastewater contaminated with p-cresol using Pseudomonas putida immobilized in polyvinyl alcohol (PVA) gel

In this study, the biodegradation of simulated wastewater containing p-cresol has been carried out using Pseudomonas putida immobilized in PVA gel, in batch and continuous reactors. The effects of initial concentration, temperature, pH and PVA volume fraction on the biodegradation of p-cresol were evaluated in a batch SBBR. Continuous experiments were also carried out to study the effect of other operating parameters such as air flow rate and residence time on the biodegradation efficiency. The batch experimental results indicated that the biodegradation capabilities of P. putida are highly affected by temperature, pH and PVA vol.% and optimum performance were obtained at 35°C, 8 and 40%, respectively. The biomass did not seem to be inhabited by high concentration of p-cresol and the biodegradation data fitted well the Monod non-inhibitory Model. The kinetics data obtained from the Monod model were utilized in modeling the continuous biodegradation process and gave very good agreement with experimental results.

Bioenergetic Strategy for the Biodegradation of p-Cresol by the Unicellular Green Alga Scenedesmus obliquus

Cultures from the unicellular green alga Scenedesmus obliquus biodegrade the toxic p-cresol (4-methylphenol) and use it as alternative carbon/energy source. The biodegradation procedure of p-cresol seems to be a two-step process. HPLC analyses indicate that the split of the methyl group (first step) that is possibly converted to methanol (increased methanol concentration in the growth medium), leading, according to our previous work, to changes in the molecular structure and function of the photosynthetic apparatus and therefore to microalgal biomass increase. The second step is the fission of the intermediately produced phenol. A higher p-cresol concentration results in a higher p-cresol biodegradation rate and a lower total p-cresol biodegradability. The first biodegradation step seems to be the most decisive for the effectiveness of the process, because methanol offers energy for the further biodegradation reactions. The absence of LHCII from the Scenedesmus mutant wt-lhc stopped the methanol effect and significantly reduced the p-cresol biodegradation (only 9%). The present contribution deals with an energy distribution between microalgal growth and p-cresol biodegradation, activated by p-cresol concentration. The simultaneous biomass increase with the detoxification of a toxic phenolic compound (p-cresol) could be a significant biotechnological aspect for further applications.

Biodegradation of p-cresol by aerobic granules in sequencing batch reactor

The cultivation of aerobic granules in sequencing batch reactor for the biodegradation of p-cresol was studied. The reactor was started with 100 mg/L of p-cresol. Aerobic granules first appeared within one month of start up. The granules were large and strong and had a compact structure. The diameter of stable granules was in the range of 1–5 mm. The integrity coefficient and granules density was found to be 96% and 1046 kg/m3, respectively. The settling velocity of granules was found to be in the range of 2×10−2–6×10−2 m/sec. The aerobic granules were able to degrade p-cresol upto 800 mg/L at a removal efficiency of 88%. Specific p-cresol degradation rate in aerobic granules followed Haldane model for substrate inhibition. High specific p-cresol degradation rate up to 0.96 g p-cresol/(g VSS·day) were sustained upto p-cresol concentration of 400 mg/L. Higher removal efficiency, good settling characteristics of aerobic granules, makes sequencing batch reactor suitable for enhancing the microorganism potential for biodegradation of inhibitory compounds.

Biodegradation of P-Cresol by Mixed Culture in Batch Reactor – Effect of the Three Nitrogen Sources Used

Phenols are distributed either as nature or artificial mono-aromatic compounds in various environmental sites as major pollutants. Their existence in wastes from industrial processes such as oil refineries, coking plants, wastewater treatment plants, petroleum-based processing, phenols resin industry manufacturing and plants, has been well established. Many processes have been used for the remediation of Phenolic compounds. Conventional methods of treatment have been largely chemical or physical, but these processes have led to secondary effluent problems and costly. Biological treatment is an effective method that is used where many micro-organisms can be growing on Phenolic compounds as the sole source of carbon.The temperature (30°C), the stirring velocity (200 r/min), NaH2PO4 concentration (3g. L-1), MgSO4 concentration (0.1g. L-1), initial concentration of p-cersol (100mg. L-1) and KH2PO4 concentration (3g. L-1) for (NH4)2SO4, (3g. L-1) for NH4NO3, (3g. L-1) for NH4Cl; while the initial concentration of nitrogen sources ((NH4)2SO4, NH4NO3, NH4Cl) was varied in the following range, 0 – 2g. L-1. All experiments were carried out at a given initial bacterial concentration, 0.08g.L-1 (based on optical density determination, 0.079).Irrespective of the culture conditions, total p-cresol degradation (100 m g. L-1) was recorded for culture time ranging from 32.5 to 49h. the optimal concentration were therefore, 1g. L-1 for all nitrogen sources, leading to a specific growth rate of 0.3 h-1. Higher maximum specific growth rate values were recorded during this work, if compared to those reported in the available literature, even those dealing with mixed culture. This result showed the relevance of the specific microbial consortium used.Two mathematical models were used to describe the length of lag phase versus initial nitrogen concentration; the growth length of lag phase was fitted using polynomial models, the correlation coefficient was varied in the following range, 0.99 – 1.

Determination of biodegradability of phenolic compounds, characteristic to wastewater of the oil-shale chemical industry, on activated sludge by oxygen uptake measurement

The aim of this study was to investigate the biodegradation of phenol, o-cresol and p-cresol individually and as bi-substrate mixtures at low initial substrate concentrations. Activated sludge was taken from the Kohtla-Järve wastewater treatment plant, Estonia, which is also treating phenolic wastewater from the oil-shale chemical industry and is considered to be acclimated to the phenolic compounds. Respirometric data have been used for evaluation of the kinetic parameters describing the bio-oxidation of substrates. Activated sludge was able to degrade phenol and p-cresol faster than o-cresol, showing better affinity to p-cresol. However, at higher concentrations, phenol and p-cresol exhibited also an inhibitory effect to the microorganisms. The highest values for maximum rate of oxygen uptake () were obtained for the bi-substrate system of phenol–p-cresol among the mixtures containing both substrates at equal concentrations from 0.005 mM to 0.050 mM. Concerning the systems containing one substrate at 0.1 mM and the other substrate varied in the abovementioned range, the highest values were found for phenol–o-cresol(0.1 mM). The interaction parameters indicated that phenol had a stronger inhibition effect on the biodegradation of p-cresol than p-cresol had on the biodegradation of phenol. However, the obtained interaction parameters for systems of phenol–o-cresol indicated that o-cresol had a stronger inhibition effect on the biodegradation of phenol, which in turn had a mild inhibition or even enhancing effect on the biodegradation of o-cresol. In the case of a 1:1 mixture, phenol and o-cresol had a similar mild inhibition effect on each other's biodegradation.

Kinetics studies of p-cresol biodegradation by using Pseudomonas putida in batch reactor and in continuous bioreactor packed with calcium alginate beads

Present study deals with the biodegradation of p-cresol by using Pseudomonas putida in a batch reactor and a continuous bioreactor packed with calcium alginate beads. The maximum specific growth rate of 0.8121 h(-1) was obtained at 200 mg L(-1) concentration of p-cresol in batch reactor. The maximum p-cresol degradation rate was obtained 6.598 mg L(-1) h(-1) at S(o)=200 mg L(-1) and 62.8 mg L(-1) h(-1) at S(o)=500 mg L(-1) for batch reactor and a continuous bioreactor, respectively. The p-cresol degradation rate of continuous bioreactor was 9 to 10-fold higher than those of the batch reactor. It shows that the continuous bioreactor could tolerate a higher concentration of p-cresol. A Haldane model was also used for p-cresol inhibition in batch reactor and a modified equation similar to Haldane model for continuous bioreactor. The Haldane parameters were obtained as µ(max) 0.3398 h(-1), K(s) 110.9574 mg L(-1), and K(I) 497.6169 mg L(-1) in batch reactor. The parameters used in continuous bioreactor were obtained as D(max) 91.801 mg L(-1) h(-1), K(s) 131.292 mg L(-1), and K(I) 1217.7 mg L(-1). The value K(I) of continuous bioreactor is approximately 2.5 times higher than the batch reactor. Higher K(I) value of continuous bioreactor indicates P. putida can grow at high range of p-cresol concentration. The ability of tolerance of higher p-cresol concentrations may be one reason for biofilm attachment on the packed bed in the continuous operation.

Sequential degradation of p-cresol by photochemical and biological methods

Sequential photo- and biodegradation of p-cresol was studied using a mercury lamp, as well as KrCl and XeCl excilamps. Preirradiation of p-cresol at a concentration of 10(-4) M did not affect the rate of its subsequent biodegradation. An increase in the concentration of p-cresol to 10(-3) M and in the duration preliminary UV irradiation inhibited subsequent biodegradation. Biodegradation of p-cresol was accompanied by the formation of a product with a fluorescence maximum at 365 nm (lambdaex 280 nm), and photodegradation yielded a compound fluorescing at 400 nm (lambdaex 330 nm). Sequential UV and biodegradation led to the appearance of bands in the fluorescence spectra that were ascribed to p-cresol and its photolysis products. It was shown that sequential use of biological and photochemical degradation results in degradation of not only the initial toxicant but also the metabolites formed during its biodegradation.

Phenol and cresol mixture degradation by the yeast Trichosporon cutaneum

Most industrial wastes contain different organic mixtures, making important the investigation on the microbial destruction of composite substrates. The capability of microbes to remove harmful chemicals from polluted environments strongly depends on the presence of other carbon and energy substrates. The effect of mixtures of phenol- and methyl-substituted phenols (o-, m-, p-cresol) on the growth behaviour and degradation capacity of Trichosporon cutaneum strain was investigated. The cell-free supernatants were analysed by HPLC. It was established that the presence of o-, m- and p- cresol has not prevented complete phenol assimilation but had significant delaying effect on the phenol degradation dynamics. The mutual influence of phenol and p-cresol was investigated. We developed the kinetic model on the basis of Haldane kinetics, which used model parameters from single-substrate experiments to predict the outcome of the two-substrate mixture experiment. The interaction coefficients indicating the degree to which phenol affects the biodegradation of p-cresol and vice versa were estimated. Quantitative estimation of interaction parameters is essential to facilitate the application of single or mixed cultures to the bio-treatment of hazardous compounds.

Biodegradation of p-cresol by immobilized cells of Bacillus sp. strain PHN 1

The Bacillus sp. strain PHN 1 capable of degrading p-cresol was immobilized in various matrices namely, polyurethane foam (PUF), polyacrylamide, alginate and agar. The degradation rates of 20 and 40 mM p-cresol by the freely suspended cells and immobilized cells in batches and semi-continuous with shaken cultures were compared. The PUF-immobilized cells achieved higher degradation of 20 and 40 mM p-cresol than freely suspended cells and the cells immobilized in polyacrylamide, alginate and agar. The PUF- immobilized cells could be reused for more than 35 cycles, without losing any degradation capacity and showed more tolerance to pH and temperature changes than free cells. These results revealed that the immobilized cell systems are more efficient than freely suspended cells for degradation of p-cresol.

Biodegradation kinetic studies for the removal of p-cresol from wastewater using Gliomastix indicus MTCC 3869

Biodegradation of p-cresol by a pure culture of new filamentous fungal strain Gliomastix indicus was studied. The fungus strain was acclimatized to the higher concentration of 700 mg/l of p-cresol in modified czapeck medium over a period of two months. The lag period was 24 h. The shake flask batch experiments were carried out at temperature of 28 °C and pH of 6 over a wide range of initial p-cresol concentration (10–700 mg/l) keeping initial biomass concentration constant at 18.72 mg/l. Experimentally it was observed that p-cresol was inhibitory type substrate and the inhibition effect of p-cresol became predominant above a concentration of 50 mg/l. The kinetics of cell growth and p-cresol degradation were investigated. Six kinetic models (Haldane, Andrews, Webb, Yano, Aiba, and Teissier) were fitted to the experimental growth kinetic data. Models by Haldane, Andrews, Webb and Yano (correlation coefficient R 2 > 0.99) were found to be most suitable models. In addition, the variation of observed yield coefficient Y X with specific growth rate μ g was investigated. The maintenance energy coefficient and true growth yield coefficient, were found to be 0.0227 h −1 and 1.0708 (mg/mg), respectively. The specific substrate utilization rate was represented in terms of specific biomass growth rate. The decay coefficient was found to be 0.0055 h −1. The effect of pH and nitrogen source of medium on biodegradation of p-cresol was investigated as well.