Biodegradation Of Chlorophenols Research Articles

Dynamical analysis of a chemostat model for 4-chlorophenol and sodium salicylate mixture biodegradation

We consider a mathematical continuous-time model for biodegradation of 4-chlorophenol and sodium salicylate mixture by the microbial strain Pseudomonas putida in a chemostat. The model is described by a system of three nonlinear ordinary differential equations and is proposed for the first time in the paper [Y.-H. Lin, B.-H. Ho, Biodegradation kinetics of phenol and 4-chlorophenol in the presence of sodium salicylate in batch and chemostat systems, Processes, 10:694, 2022], where the model is only quantitatively verified. This paper provides a detailed analysis of the system dynamics. Some important basic properties of the model solutions like existence, uniqueness and uniform boundedness of positive solutions are established. Computation of equilibrium points and study of their local asymptotic stability and bifurcations in dependence of the dilution rate as a key model parameter are also presented. Thereby, particular intervals for the dilution rate are found, where one or three interior (with positive components) equilibrium points do exist and possess different types of local asymptotic stability/instability. Hopf bifurcations are detected leading to the occurrence of stable limit cycles around some interior equilibrium points. A transcritical bifurcation also exists and implies stability exchange between an interior and the boundary (washout) equilibrium. The results are illustrated by lots of numerical examples.

Effective biodegradation of chlorophenols, sulfonamides, and their mixtures by bacterial laccase immobilized on chitin

Coexisting multi-pollutants like sulfonamides (SAs) and chlorophenols (CPs) in the ecological environment pose a potential risk to living organisms. The development of a strategy for the effective removal of multiple pollutants has become an urgent need. Herein, we systematically investigated the potential of immobilized bacterial laccase to remove chlorophenols (CPs), sulfonamides (SAs), and their mixtures. Laccase from Bacillus pumilus ZB1 was efficiently immobilized on chitin and its thermal stability, pH stability, and affinity to substrates were improved. Reusability assessment showed the immobilized laccase retained 75.5% of its initial activity after five cycles. The removal efficiency of CPs and SAs by immobilized laccase was significantly improved compared with that of free laccase. In particular, the removal of 2,4-dichlorophenol and 2,4,6-trichlorophenol reached 96.9% and 89.3% respectively within 8 h. The immobilized laccase could remove 63.70% of 2,4-dichlorophenol after four cycles. The degradation pathways of 2,4-dichlorophenol and sulfamethazine were proposed via LC/MS analysis. When the co-pollutants containing 2,4,6-trichlorophenol and sulfamethoxazole, immobilized laccase showed 100% removal of 2,4,6-trichlorophenol and 38.71% removal of sulfamethoxazole simultaneously. Cytotoxicity and phytotoxicity tests indicated that immobilized laccase can alleviate the toxicity of co-pollutants. The results demonstrate that chitin-based laccase immobilization can be an effective strategy for the removal of SAs, CPs, and their co-pollutants.

Kinetic Study of 4-Chlorophenol Biodegradation by Acclimated Sludge in a Packed Bed Reactor

In this study, batch experiments were conducted to evaluate the degradation of 4-CP using acclimated sludge. The Monod and Haldane models were employed to fit the specific growth rate with various initial 4-CP concentrations of 67–412 mg/L in the batch experiments. Haldane kinetics showed a better fit to experimental results than Monod kinetics. The kinetic parameters were obtained from a comparison of Monod and Haldane kinetics with batch experimental data. The values of μm and KS were found to be 0.691 d−1 and 5.62 mg/L, respectively, for Monod kinetics. In contrast, the values of μm, KS, and KI were 1.30 d−1, 8.38 mg/L, and 279.4 mg/L, respectively, for Haldane kinetics. The kinetic parameters in Haldane kinetics were used as input parameters for the kinetic model system of the packed bed reactor (PBR). The continuous flow PBR was conducted to validate the kinetic model system. The model-simulated results agreed well with experimental data in the PBR performance operation. At the steady-state stage, the removal efficiency of 4-CP was 70.8–96.1%, while the hydraulic retention time (HRT) was 2.5 to 12.4 h. The corresponding removal of 4-CP was assessed to be 94.6 and 96.1% when the inlet 4-CP loading rate was increased from 0.11 to 0.51 kg/m3-d. The approaches of kinetic models and experiments presented in this study can be applied to design a PBR for 4-CP treatment in wastewater from the effluents of various industries.

The Biodegradation of 4-Chlorophenol in a Moving Bed Biofilm Reactor Using Response Surface Methodology: Effect of Biogenic Substrate and Kinetic Evaluation.

4-Chlorophenol (4-CP) is a persistent organic pollutant commonly found in petrochemical effluents. It causes toxic, carcinogenic and mutagenic effects on human beings and aquatic lives. Therefore, an environmentally benign and cost-effective approach is needed against such pollutants. In this direction, the chlorophenol degrading bacterial consortium consisting of Bacillus flexus GS1 IIT (BHU) and Bacillus cereus GS2 IIT (BHU) was isolated from a refinery site. A composite biocarrier namely polypropylene-polyurethane foam (PP-PUF) was developed for bacterial cells immobilization purpose. A lab-scale moving bed biofilm reactor (MBBR) packed with Bacillus sp. immobilized PP-PUF biocarrier was employed to analyse the effect of peptone on biodegradation of 4-CP. The statistical tool, i.e. response surface methodology (RSM), was used to optimize the process variables (4-CP concentration, peptone concentration and hydraulic retention time). The higher values of peptone concentration and hydraulic retention time were found to be favourable for maximum removal of 4-CP. At the optimized process conditions, the maximum removals of 4-CP and chemical oxygen demand (COD) were obtained to be 91.07 and 75.29%, respectively. In addition, three kinetic models, i.e. second-order, Monod and modified Stover-Kincannon models, were employed to investigate the behaviour of MBBR during 4-CP biodegradation. The high regression coefficients obtained by the second-order and modified Stover-Kincannon models showed better accuracy for estimating substrate degradation kinetics. The phytotoxicity study supported that the Vigna radiata seeds germinated in treated wastewater showed higher growth (i.e. radicle and plumule) than the untreated wastewater.

Enhanced 4-chlorophenol biodegradation by integrating Fe2O3 nanoparticles into an anaerobic reactor: Long-term performance and underlying mechanism

Enhanced 4-chlorophenol biodegradation by integrating Fe2O3 nanoparticles into an anaerobic reactor: Long-term performance and underlying mechanism

A comparative study of 4-chlorophenol biodegradation in a packed bed and moving bed bioreactor: Performance evaluation and toxicity analysis

In this study, sponge-modified carrier, i.e., polypropylene–polyurethane​ foam (PP–PUF)was used in the bioreactors, namely moving bed bioreactor (MBBR) and packed bed bioreactor (PBBR), for the biodegradation of 4-CP. The Bacillus consortium isolated from the petroleum refinery site was used for the immobilization purpose. A comparative analysis was carried out to evaluate the performance of the MBBR and PBBR under identical conditions. The maximum removal efficiencies (REs) of 4-CP were obtained as 94.34 and 90.62 % in MBBR and PBBR, respectively, at an initial 4-CP concentration of 50 mg/L. Similarly, the chemical oxygen demand (COD) REs were found to be 83.26 and 79.37 % in MBBR and PBBR, respectively. The higher REs of 4-CP and COD were observed in MBBR due to the high growth of biomass. The total biomass found in the MBBR and PBBR was in the range of 1595–1752 mg/L and 1468–1640 mg/L, respectively. Andrew–Haldane model was more accurately predicted the growth inhibition of the Bacillus consortium compared to the Monod model. Moreover, the kinetic parameters were evaluated and found to be μmax: 0.19 h−1; Ks: 20.08 mg/L for Monod model, and μmax: 0.212 h−1; Ks: 7.05 mg/L; Ki: 163.67 mg/L for Andrew–Haldane model. The toxicity of the treated wastewater was evaluated using the Resazurin reduction method, and a maximum of 90 % toxicity removal was achieved in MBBR and PBBR up to 200 mg/L of 4-CP concentration.

A robust biocatalyst based on laccase immobilized superparamagnetic Fe3O4@SiO2–NH2 nanoparticles and its application for degradation of chlorophenols

The presence of chlorophenols in water and wastewater is considered a serious environmental issue. To eliminate these micropollutants, biodegradation of chlorophenols using enzyme-nanoparticle conjugated biocatalyst, is proposed as an economical and eco-friendly method. Herein, amino-functionalized superparamagnetic Fe3O4@SiO2–NH2 nanoparticles with core-shell structure were constructed as a promising carrier for immobilization of laccase from Trametes versicolor. Compared with free laccase, Fe3O4@SiO2–NH2-Laccase displayed remarkable outcomes in all major areas such as temperature and storage stabilities, and tolerance to organic solvents and metal ions. The biocatalytic performance and reusability of Fe3O4@SiO2–NH2-Laccase were evaluated for the degradation of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) in repeated cycles. Even after 10 successive reuses, the degradation rate of 2,4-DCP and 2,4,6-TCP were found to be 54.9% and 68.7%, respectively. The influences of solution pH, initial chlorophenol concentration, and temperature on the degradation rate of these two chlorophenols were evaluated. The degradation intermediate products including dimers, trimers, and tetramers of 2,4-DCP and 2,4,6-TCP were identified. Release of chloride ions was observed during the enzymatic degradation of these two chlorophenols. Based on the determination of intermediate products and released chloride ions, the degradation pathway that was involved in dehydrogenation, reactive radical intermediates formation, dechlorination, self-coupling and oligomers/polymers formation was proposed. The toxicity of these two chlorophenols and their intermediates was substantially reduced during the enzymatic degradation. The results of this study might present an alternative clean biotechnology for the remediation of 2,4-DCP and 2,4,6-TCP contaminated water matrices.

Biodegradation of 4-chlorophenol in batch and continuous packed bed reactor by isolated Bacillus subtilis

In present work, biodegradation of 4-Chlorophenol (4-CP) has been successfully achieved using bacteria i.e. Bacillus subtilis (MF447841.1), which was isolated from the wastewater of a nearby drain of Hyundai Motor Company service centre, Agartala, Tripura (India). Geonomic identification was carried out by 16 S rDNA technique and phylogenetic processes. Both, batch and column mode of experiments were performed to optimize various parameters (initial concentration, contact time, dosages etc.) involved in the significant biodegradation of 4-CP. Based on R2 value (0.9789), the Levenspiel's model was found to be best fit than others. The kinetic parameters; specific growth rate (μ), yield of cell mass (YX/S), and saturation constant (KS), were obtained as 0.6383 (h−1), 0.35 (g/g), and 0.006884 (g/L), respectively. The isolated strain has shown the ability of degrading 4-CP up to 1000 mg/L initial concentration within 40 h. Bacterial strain was immobilized via developing calcium alginate beads along by optimizing weight proportion of calcium chloride and sodium alginate and size of the bead for further experiments. Various process parameters i.e. initial feed concentration, bed height, rate of flow of were optimized during packed bed reactor (PBR) study. Maximum biodegradation efficiency of 4-CP was observed as 45.39% at initial concentration of 500 mg/L within 105 min, using 2 mm size of immobilized beads which were formed using 3.5% w/v of both calcium chloride and sodium alginate within. Thus, Bacillus subtilis (MF447841.1) could be used for biological remediation of 4-CP pollutant present in wastewater. Moreover, because of affordable and eco-friendly nature of water treatment, relatively it has the better scope of commercialization.

Parametric optimization by Taguchi orthogonal array methodology for enhanced biodegradation of 4-chlorophenol by an isolated bacterial consortium

Parametric optimization by Taguchi orthogonal array methodology for enhanced biodegradation of 4-chlorophenol by an isolated bacterial consortium

Intensified 4-chlorophenol biodegradation in an aerobic sequencing batch reactor: Microbial and kinetic properties evaluation

In this paper, the microbial and biodegradation kinetics of acclimated-mixed sludge to 4-chlorophenol (4-CP) were investigated in an aerobic sequencing batch reactor (SBR). A molecular technique was applied to evaluate the bacterial variety and role in mixed biomass. Culture isolation and a 16S rDNA sequence authenticated the domination of Gram-positive high-G+C bacilli and coccobacilli with a 99% similarity belonging to the group of Actinobacteria. These isolates include Brevibacterium casei DSM20657, Corynebacterium callunae 10338, Microbacterium oxydan s XH0903, and Kocuria rhizophila Ag09. Those strains in the mixed condition aerobically removed 4-CP till a concentration of 800 mg L −1 . The biodegradation kinetics of 4-CP were adequately predicted by the Haldane formulae with a half-saturation constant ( K s ) and an inhibition constant ( K i ), of 9.12 and 609.7 mg L −1 , respectively. The maximum specific degradation rate ( q m ) was 20.33 mg 4-CP g −1 VSS h −1 . Amounts of the yield coefficient (Y) were among 0.25 and 0.48 mg VSS mg −1 COD. However, due to congregate of 5-chloro-2-hydroxymuconic semialdehyde (CHMS), an intermediate meta-cleavage product of 4-CP, the pure strains isolated from mixed sludge did not show a higher 4-CP-removal efficiency compared with the mixed sludge. Therefore, the use of mixed biomass in engineering systems has attracted increased attention for both environmental and biotechnological applications. • Representing firstly Gram positive high-G+C bacteria degrading 4-CP based on 16S rDNA. • Kinetic properties of acclimated-mixed sludge treating high concentration of 4-CP. • The Y value was observed to be from 0.25 to 0.48 mg VSS mg -1 COD. • The critical concentration of 4-CP and the K i /K s ratio were 74.5 mg L -1 and 66.85, respectively. • High concentration of 4-CP could be removed by SBR with acclimated-mixed sludge.

Effect of transient pH variation on microbial activity and physical characteristics of aerobic granules treating 4-chlorophenol

Chlorophenols are inhibitory compounds that can be biodegraded by aerobic granules in discontinuous processes. Many industrial wastewaters are characterized by transient pH variation over time. These pH changes could affect the overall granule structure and microbial activity during the chlorophenol biodegradation. The objective of this research was to evaluate the effects of transient pH variation on the specific degradation rate (q), granule integrity coefficient (IC), and size in sequencing batch reactors treating 4-chlorophenol (4-CP). First, aerobic granules were acclimated for efficient 4-CP degradation (>99%). The acclimated granules consisted of 55.7% of the phyla Proteobacteria and 40.6% of Bacteroidetes. The main bacteria belong to the order Sphingobacteriales (24%), as well as Amaricoccus, Acidovorax, Shinella, Rhizobium, and Flavobacterium, some of which are new genera reported in acclimated granules degrading 4-CP. Then, pH changes were applied to the acclimated aerobic granules, observing that acid pHs decreased to a greater extent the specific degradation rate (67% to 99%) than basic pHs (34% to 80%). These pH changes caused the granule disaggregation but with lower effects on the IC. The effects of pH change were mainly on the microbial activity more than the physical characteristics of aerobic granules degrading 4-CP.

Optimization of various process parameters for biodegradation of 4-chlorophenol using Taguchi methodology

Abstract A statistical optimization was performed to achieve a higher yield of cell growth and 4-chlorophenol (4-CP) biodegradation, where isolated Bacillus subtilis MF447840.1 was used as biocatalyst. Taguchi methodology was used to evaluate the optimum condition for eleven process parameters. Six media components such as ammonium nitrate, magnesium sulfate, dipotassium phosphate, monopotassium phosphate, calcium chloride, and trace element, and five physicochemical factors such as pH, temperature, agitation, inoculum size, and incubation time, were considered for optimization owing to their significant effect on cell growth and 4-CP biodegradation. Orthogonal Arrays (OA) layout of L27 was used for designing of various experimental trials. Signal to noise (S/N) ratio was used to evaluate the individual effects of process parameters and their optimal level during evaluation of cell growth and 4-CP biodegradation. Optimization studies revealed that 911.45 mg/L of biomass yield and 1000 mg/L of 4-CP biodegradation were found with ammonium nitrate (0.75 g/L), magnesium sulfate (0.25 g/L), dipotassium phosphate (0.75 g/L), monopotassium phosphate (0.25 g/L), calcium chloride (0.02 g/L), trace element (1%), pH (7.5), temperature (37 °C), agitation (150 rpm), inoculum size (10%), and incubation time (40 h).

Co-metabolic biodegradation of 4-chlorophenol by photosynthetic bacteria

ABSTRACT Environmental contamination by 4-chlorophenol (4-CP) is a major concern. Photosynthetic bacteria have the ability to biodegrade 4-CP under dark aerobic conditions. In this study, we found that using different carbon sources (i.e. glucose, sodium acetate, sodium propionate sucrose, and malic acid) as co-metabolic substrates accelerated the biodegradation of 4-CP, and this acceleration was especially pronounced in the glucose treatment. A maximum degradation rate of 96.99% was reached under a concentration of 3.0 g·L−1 after 6 days of culture. The optimum conditions were pH 7.5, a temperature of 30°C, and a rotation speed of 135 rpm. The biodegradation of 4-CP was achieved at a range of salinities (0–3.0% NaCl, w/v). The biodegradation kinetics agreed with the Haldane model, and the kinetic constants were r max = 0.14 d−1, Km = 33.9 mg·L−1, and Ki = 159.6 mg·L−1. Additionally, the coexistence of phenol or 2,4-dichlorophenol (2, 4-DCP) had a certain impact on the degradation of 4-CP under dark aerobic conditions. When the coexisting phenol concentration reached 100 mg·L−1, the maximum degradation rate of 4-CP reached 90.20%. The degradation rate of 4-CP decreased as the concentration of coexisting 2, 4-DCP increased.

Studies on Biodegradation of 4-Chlorophenol and 4-Nitrophenol by Isolated Pure Cultures

Metabolically versatile pure cultures were isolated from textile dye effluent and petrochemical industry which were able to utilize 150 mg/l of 4-Chlorophenol and 85 mg/l of 4-Nitrophenol as the sole carbon and energy source respectively. Phylogenetic analysis based on 16 S rRNA gene sequence reveals that the strains were found to be phylogenetically close to Bacillus cereus HWB1 and Pseudomonas taiwanensis ECAe22 respectively. Optimization of physicochemical parameters was performed with Change of one variable at a time (COVT) approach. Optimized physical parameters for degradation by Bacillus cereus HWB1 was found to be 30 0C, pH 7 and 150 rpm whereas for Pseudomonas taiwanensis ECAe22 it was found to be 30 0C, pH 8.5 and 150 rpm. Supplementation of an additional substrate such as yeast extract was found to increase the rate of 4-Chlorophenol and 4-Nitrophenol degradation owing to the increase in biomass production resulting in enhanced biodegradation. Biodegraded samples of these phenolic compounds showed negligible phytotoxicity as compared to the untreated samples thereby proving that employing these pure cultures can help in mitigating environmental contamination by phenolic compounds in the near future.Keywords: Biodegradation, 4-Chlorophenol,4-Nitrophenol, pure cultures,16S rRNA, phylogenetic analysisAbbreviation: 4-CP: 4-Chlorophenol; 4-NP: 4-Nitrophenol; AU: Absorbance Unit; MSM: MinimalSalt Media

A kinetic study of 4-chlorophenol biodegradation by the novel isolated Bacillus subtilis in batch shake flask

A kinetic study of 4-chlorophenol biodegradation by the novel isolated Bacillus subtilis in batch shake flask

Shielding immobilized biomass cryogel beads with powdered activated carbon for the simultaneous adsorption and biodegradation of 4-chlorophenol

In order to retain a high concentration of activated sludge in the wastewater treatment plant, the dense activated sludge is entrapped into the polyvinyl alcohol (PVA) cryogel beads. For protecting the entrapped activated sludge biomass from the inhibitory effect exerted by recalcitrant pollutant, i.e., 4-chlorophenol (4-CP), the novel PVA cryogel beads with external surface covered by the powdered activated carbon (PAC) were successfully synthesized in this study. The synthesis was achieved by extruding the biomass-PVA polymeric matrix into the gelatin solution containing PAC. The maximum PAC density on the external surface of cryogel beads was calculated to be in the range of 938–978 mg/m2. The PAC distributed on the external surface of cryogel beads was found to possess a higher 4-CP adsorption capacity than the beads with homogenized PAC. These cryogel beads were also capable of shielding the activated sludge biomass entrapped within beads from being directly exposed to the inhibitory effect of 4-CP via adsorption by PAC distributed on the external surface. Thus, only low concentration of 4-CP was diffused into the beads and biodegraded to achieve a total removal of 4-CP. This beneficial effect was later confirmed could last for more than 20 cycles of uses in removing 4-CP via the simultaneous adsorption and biodegradation processes.

Enhancing chlorophenol biodegradation: Using a co-substrate strategy to resist photo-H2O2 stress in a photocatalytic-biological reactor

Intimately coupled photocatalysis and biodegradation (ICPB) is an emerging technology for treating refractory wastewater. The prerequisite of successful ICPB is that photocatalytic reactive oxygen species (ROSs) attack refractory pollutants and yield biodegradable intermediates, but “instantly” extinct before they transfer to the biofilms. However, photocatalytic induced H2O2 (a typical ROS) is different from others due to its long half-life. Photo-H2O2 in ICPB could potentially damage the biofilm; however, this has not been verified to date. In this study, we show that photo-H2O2 damages biofilms in ICPB, and we successfully addressed this issue using a strategy with the co-substrate (NaAC). Under H2O2 stress, the living cell percentage in ICPB dropped significantly, and the cell morphology presented the disinfection of bacteria cells, with enlarged size and disappeared organelles. By adding NaAC, the living cell percentage increased by 19.6% and the bacterial intracellular structure became integrated. The Shannon index increased from 3.45 to 4.05, indicating enhanced microbial diversity. Thauera and Dechloromonas were dominant genera, which played important roles in the breaking of the aromatic ring and in dechlorinating. As a result, 4-CP removal and mineralization increased by ∼27% and ∼23%, respectively. Here, we identified the negative effects of photo-H2O2 on the microbial survival of ICPB and for the first time propose an efficient co-substrate strategy to remedy this issue.

Kinetics of cometabolic biodegradation of 4-chlorophenol and phenol by Stenotrophomonas maltophilia KB2

Kinetics of cometabolic biodegradation of 4-chlorophenol and phenol by Stenotrophomonas maltophilia KB2

4-Chlorophenol biodegradation facilitator composed of recombinant multi-biocatalysts immobilized onto montmorillonite

A biodegradation facilitator which catalyzes the initial steps of 4-chlorophenol (4-CP) oxidation was prepared by immobilizing multiple enzymes (monooxygenase, CphC-I and dioxygenase, CphA-I) onto a natural inorganic support. The enzymes were obtained via overexpression and purification after cloning the corresponding genes (cphC-I and cphA-I) from Arthrobacter chlorophenolicus A6. Then, the recombinant CphC-I was immobilized onto fulvic acid-activated montmorillonite. The immobilization yield was 60%, and the high enzyme activity (82.6%) was retained after immobilization. Kinetic analysis indicated that the Michaelis-Menten model parameters for the immobilized CphC-I were similar to those for the free enzyme. The enzyme stability was markedly enhanced after immobilization. The immobilized enzyme exhibited a high level of activity even after repetitive use (84.7%) and powdering (65.8%). 4-CP was sequentially oxidized by a multiple enzyme complex, comprising the immobilized CphC-I and CphA-I, via the hydroquinone pathway: oxidative transformation of 4-CP to hydroxyquinol followed by ring fission of hydroxyquinol.

Monitoring and modeling 4-chlorophenol biodegradation kinetics by phenol-acclimated activated sludge by using open respirometry.

The aim of this study was to analyze the mechanisms, stoichiometry, and stability of 4-chlorophenol (4CP) biodegradation kinetics by phenol-acclimated activated sludge using open respirometry. While the removal of 4CP was higher than 98%, the removal of chemical oxygen demand (COD) ranged between 69 and 79% due to the accumulation of an intermediate metabolite. The value obtained from respirometric profiles for the stoichiometric ratio of O2 to 4CP (YO2/4CP) was 1.95±0.04mol of oxygen consumed per mol of 4CP removed. This YO2/4CP value reflected the action of the oxygenases responsible for the first steps of the aerobic oxidation of 4CP. The 4CP degradation activity decreased noticeably when successive pulses of 4CP were added to the respirometer. A mathematical model was developed to represent the aerobic biodegradation of 4CP. The fitted model adequately predicted the oxygen consumption rate, total phenols, and soluble COD concentrations as a function of time. The results presented could help to predict the dynamic of biodegradation of chlorophenols in a biological wastewater treatment system.