Degradation Of Persistent Organic Pollutants Research Articles

A Review of the Mechanisms of Single-Atom-Based Advanced Oxidation Processes for the Degradation of Persistent Organic Pollutants in Water Environments

A Review of the Mechanisms of Single-Atom-Based Advanced Oxidation Processes for the Degradation of Persistent Organic Pollutants in Water Environments

Visible-light enhanced tetracycline degradation via SnO2/TiO2-Ni@rGO ternary heterostructures.

This study explores the synthesis, characterization, and photocatalytic performance of a SnO2/TiO2-Ni@rGO nanocomposite for tetracycline (TC) degradation under visible light irradiation. The nanocomposite was precisely designed to enhance structural stability, charge transfer efficiency, and catalytic activity. X-ray diffraction (XRD) analysis confirmed the structural integrity of the SnO2/TiO2-Ni@rGO composite, demonstrating excellent reusability and resistance to photo-corrosion after multiple cycles. Photocatalytic experiments revealed that the SnO2/TiO2-Ni@rGO nanocomposite significantly outperformed individual SnO2/TiO2-Ni and rGO catalysts, achieving a remarkable 94.6% degradation of TC within 60 min. The degradation process followed pseudo-first-order kinetics, with a rate constant (k) of 0.046 min-1. The Z-scheme charge transfer mechanism facilitated efficient separation and migration of photogenerated charge carriers, generating reactive oxygen species such as superoxide (•O2 -) and hydroxyl (•OH) radicals crucial for the oxidation of TC. Radical scavenger studies confirmed that superoxide and hydroxyl radicals were the primary active species. The SnO2/TiO2-Ni@rGO composite also exhibited excellent reusability, maintaining high catalytic performance over four consecutive cycles. These findings suggest that the SnO2/TiO2-Ni@rGO nanocomposite is a promising candidate for the efficient and sustainable photocatalytic degradation of persistent organic pollutants like TC, offering significant potential for environmental remediation applications.

Advanced oxidation processes of persulfate coupled with sequencing batch reactor activated sludge process (AOPs-SBR): Biodegradability and toxicity analysis of degradation intermediates

Although carbon-based catalysts are of great significance for potential application in advanced oxidation processes of persulfate, the biotoxicity and biodegradability of degradation intermediates of organic pollutants have been rarely reported. Herein, carbon-based nanofiber materials are prepared by electrospinning energetic metal–organic framework (EMOF) and ferric acetylacetonate, where the puff up of the EMOF creates hierarchical porous structure during high-temperature pyrolysis and provides sufficient space to expose Fe/N active sites. When organic pollutant tetracycline (TTCH) as target contaminant, energetic MOF derived carbon/Fe nanofiber in 900C named ECFe-9, which exhibits larger specific surface area (546.8 m2/g) and higher reaction rate constant k value (0.186 min−1) than that of in 700, 800 and 1000 °C. The biotoxicity of degradation intermediates is investigated by toxicity simulation. The biodegradability is analyzed by using advanced oxidation coupled with sequencing batch reactor activated sludge process (AOPs-SBR). This study provides a new perspective for advanced oxidation processes of persulfate as pretreatment methods for aerobic biochemical degradation of persistent organic pollutants.

Photocatalyzed degradation of persistent organic pollutants via black TiO2 nanomaterials with four distinct morphologies: Energy and treatment cost estimation

For photocatalytic remediation of wastewater on an industrial scale, shaping the morphological properties of black TiO2 and reducing energy consumption and related treatment cost (t-cost) are essential. In this study, black TiO2 nanomaterials with four different morphologies—nanoparticles (TNPs), nanowires (TNWs), nanoflowers (TNFs), and nanonails (TNNs)—were produced, and their effectiveness in visible-driven photodegradation of model persistent phenolic compounds (PhCs) was evaluated. For every modification, the amount of energy consumed—primarily electrical energy (EE) and t-cost were estimated. The anatase structure was consistent throughout all the different morphological TiO2 samples, with a range of bandgaps of 2.4–2.93 eV, crystallite sizes of 13.86–18.49 nm, and significantly varying surface areas from 183.76 to 521.58 m2/g. TNFs were the most effective and versatile black TiO2 nanomaterials among the samples, as evidenced by their significantly higher removal efficiency of 77.99 % of total phenols (TPs). Furthermore, after 120 minutes of exposure to visible light, TNFs eliminated 100 % of the individual PhCs, including phenol, Ferrulic acid (FA), caffeic acid (CA), and gallic acid (GA). The TNFs required less than 170 kWh/m3 of EE with an estimated t-cost of less than 8 $/m3 for more than 80 % removal of all PhCs and reducing BOD5 and COD levels of the wastewater by 77.90 and 77.54 %, respectively. The estimated cost of the input materials was 39.52, while the EE cost was 5.045 with a total cost of 44.565 $ for producing 1 kg of the TNFs. Scavenging experiments revealed that the main reactive agents responsible for PhCs degradation were •OH radicals. This study provides evidence that adjusting the morphological characteristics of black TiO2 nanomaterials may be a useful tactic to lower the energy consumption and t-cost of photocatalytic remediation of wastewater contaminated with persistent organic pollutants.

Terpyridine-based metallo-cuboctahedron nanomaterials for efficient photocatalytic degradation of persistent organic pollutants

Terpyridine-based metallo-cuboctahedron nanomaterials for efficient photocatalytic degradation of persistent organic pollutants

Hydrodynamic Cavitation and Advanced Oxidation for Enhanced Degradation of Persistent Organic Pollutants: A Review

Hydrodynamic Cavitation and Advanced Oxidation for Enhanced Degradation of Persistent Organic Pollutants: A Review

Behavior of PCDD/Fs and PCBs from Wastewater Treatment Plants during Sewage Sludge Composting: Study of Semi-Anaerobic Conditions and Different Stages of the Process

Composting is a common treatment for the high amounts of sewage sludge produced in wastewater treatment plants, and the product is used in agriculture. Composting reduces the levels of biodegradable organic pollutants, although other compounds present in wastewater and not eliminated previously by conventional physical–chemical and chemical treatments, such as polychorodibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs), have been found in the final compost at higher levels than those observed in the initial sludge. Their formation was studied during composting under unfavorable aeration conditions and paying attention to different stages of the process. Experiments were carried out in small vessels inside a controlled oven for three types of sewage sludge. Pentachlorophenol was previously added as a dioxin precursor. A clear formation of PCDD/Fs was found, especially during the maturation stage for two experiments. Mainly octachlorodibenzo-p-dioxin (OCDD) and 1234678-heptachlorodibenzo-p-dioxin (1234678-HpCDD) to a lesser extent were formed. OCDD levels in the final samples were around 10 times higher than those of the initial mixture after removing the concentration effect. No clear formation nor degradation of PCBs was observed. The toxicity values due to PCDD/Fs and PCBs found in the initial mixtures were 1.20–2.46 ng WHO-TEQ/kg, and those from the final samples were 2.30–7.86 ng WHO-TEQ/kg. Although the toxicity values are below the most restrictive limits found in Europe in this case, toxicity could increase considerably with the presence and concentration of other precursors. Compost from sewage sludge is an ecological product, but the operating conditions must be controlled to avoid PCDD/F formation and facilitate degradation of persistent organic pollutants.

In-situ construction of AgI nanoparticle-decorated covalent triazine-based frameworks heterojunction with enhanced photocatalytic performance for the degradation of persistent organic pollutants

In this paper, a multitude of novel CTF-1/AgI (CTFA-x) type-Ⅱ heterojunction were fabricated by in-situ growth approach based on the stable covalent triazine-based framework CTFs. 2D CTF-1 with sufficient nitrogen sites anchored AgI to its matrix, supporting ample active sites for CTFA to degrade ciprofloxacin (CIP) in aqueous solution. The structural and physicochemical characteristic of the CTFA products were explored by TEM, XRD, XPS, FT-IR, BET and PL characterization. The respective roles and synergistic effects of AgI and CTF-1 are discussed. Benefiting from this unique structure, the CTF-1/AgI with the mass ratio of 1:1 (CTFA-50) demonstrated the highest photocatalytic capacity and showed a degradation efficiency of more than 90 % against CIP after 120 min under simulated sunshine irradiation. Compared to pure AgI and CTF-1, the apparent rate constant for the CIP photodegradation of CTFA-50 (0.0153 min−1) was found to be 6.7 and 8.5 times greater. The CTFA-50 catalyst possessed good structural stability and broad-spectrum applicability, and had the ability to efficiently degrade various stubborn organic matters including tetracycline (87.97 %), 2-sec-butyl-4,6-dinitrophenol (63.42 %), bisphenol A (68.22 %), rhodamine B (98.62 %), methyl orange (70.25 %), methylene blue (63.27 %). As demonstrated by the results of the radical trapping tests and EPR analysis, the photodegradation process of CIP was mostly mediated by •O2– and h+. In view of the LC/MS findings, all reaction intermediates could be determined and a reasonable photocatalytic mechanism was proposed.

Novel core-shell structural nZVI@Fe2P for sulfadiazine (SDZ) degradation: Accelerated Fe(III)/Fe(II) dynamic cycling, boosted Fenton performance and stability

Nano zero valent iron (nZVI) is widely used in traditional hydrogen peroxide (H2O2)-based Fenton reactions for the degradation of persistent organic pollutants in aqueous environments. How to restrain the blocked electron transfer aroused from thickening of the iron oxide passivation layer and reinforce the Fe(III)/Fe(II) dynamic cycling is essential for Fenton reactions. In this work, a novel core–shell structural nZVI@Fe2P was fabricated and employed for the degradation of sulfadiazine (SDZ). Compared to nZVI, the nZVI@Fe2P demonstrated a significant performance and stability in the degradation of SDZ. Completed SDZ removal is achieved in less than 15 min and the SDZ removal kept over 60% even in the ninth consecutive cycles. Although the SDZ removal decreased dramatically to only 27.4% in the tenth cycle, the value could be restored to 80.6% after a facile re-phosphorization process. Both experimental and density function theory (DFT) calculation revealed the dominant role of Fe2P in promoting H2O2 activation and strengthening the Fe(III)/Fe(II) dynamic cycling. In the nZVI@Fe2P/H2O2 system, the low impedance and high proton conductivity of the Fe2P shell layer played a dual function, i.e., accelerating electron transfer and donating electrons for the continuous Fenton reaction. This implication of these findings provides a novel strategy by integrating the state-of-the-art material science, advanced oxidation process, and mechanism elucidation for practical environmental wastewater remediation.

Insight into the photodegradation of o,p'-dichlorodiphenyltrichloroethane in a broad spectrum of irradiation light

Photolysis is the main pathway for the degradation of persistent organic pollutants (POPs). Most investigations, however, have been limited to the ultraviolet or visible region, and the reaction mechanism of infrared (IR) light is still unclear. In this study, the photodegradation of o,p'-dichlorodiphenyltrichloroethanes (o,p'-DDT) on the silica (SiO2)/air interface under different irradiation light sources was systematically investigated. Interestingly, for the first time, effective degradation of o,p'-DDT under IR light irradiation was observed, which was ascribed to the anti-Stokes Raman scattering process of SiO2. Moreover, desert sands could also serve as a vector for the photodegradation of o,p'-DDT. The lower removal efficiency of desert sands compared to pure SiO2 was a combined effect of differences in Fe3+ component and SiO2 content. It is worth noting that direct photodegradation plays a dominant role in the photodegradation of o,p'-DDT on SiO2. Besides, indirect photodegradation resulted mainly from •OH (25.0%), O2•− (6.9%), and 1O2 (5.6%) generated in the reaction system. In addition to hydroxylation and dechlorination products, the formation of four novel silicon-based products was observed, which resulted from the direct reaction of silyl radicals with o,p'-DDT. This study revealed that the specific Raman scattering effect of SiO2 played a vital role in the self-purification process of POPs upon SiO2-based environmental matrices. The light-mediated decontamination system upon SiO2 constructed in this study could provide critical information for addressing POPs contamination on sands.

Neonicotinoid Insecticide-Degrading Bacteria and Their Application Potential in Contaminated Agricultural Soil Remediation

Recent advances in the microbial degradation of persistent organic pollutants have the potential to mitigate the damage caused by anthropogenic activities that are harmfully impacting agriculture soil ecosystems and human health. In this paper, we summarize the pollution characteristics of neonicotinoid insecticides (NNIs) in agricultural fields in China and other countries and then discuss the existing research on screening for NNI-degrading functional bacterial strains, their degradation processes, the construction of microbial consortia, and strategies for their application. We explore the current needs and solutions for improving the microbial remediation rate of NNI-contaminated soil and how these solutions are being developed and applied. We highlight several scientific and technological advances in soil microbiome engineering, including the construction of microbial consortia with a broad spectrum of NNI degradation and microbial immobilization to improve competition with indigenous microorganisms through the provision of a microenvironment and niche suitable for NNI-degrading bacteria. This paper highlights the need for an interdisciplinary approach to improving the degradation capacity and in situ survival of NNI-degrading strains/microbial consortia to facilitate the remediation of NNI-contaminated soil using strains with a broad spectrum and high efficiency in NNI degradation.

Developing Prussian blue/wood-derived biochar catalyst for persistent organic pollutant degradation: Preparation, characterization, and mechanism

Biomass-derived biochar shows broad promise for persistent organic pollutants (POPs) degradation and thus establishes a more sustainable homestead. However, effective catalytic performance is still challenging. Herein, an efficient catalyst (Prussian blue decorated wood-derived biochar, PBB) was constructed by introducing Prussian blue (PB) into wood-based biochar to activate peroxymonosulfate (PMS) for removing POPs. After anchoring of PB, the degradation performance of biochar was enhanced (degradation efficiency of methylene blue (MB, 20 mg/L) increased from 52% of biochar to 95% of PBB within 60 min). The PBB presents effective MB degradation performance with a wide pH value (3.0 < pH < 11.0) or co-existing diverse anions (Cl−, NO3−, H2PO4−, and HCO3−). Electron paramagnetic resonance (EPR) analysis as well as electrochemical tests confirmed that the non-radical pathway (1O2) is the key to biochar activation of PMS, but by restricting PB into the biochar, the radical pathway (SO4•- and •OH), the non-radical pathway (1O2), and direct electron transfer can work together to activate PMS. In addition, the degradation efficiency could remain about 80% after five-time cyclic tests. This work elucidates the role of PB nanoparticles in enhancing biochar catalysts, which can inspire the development of a carbon-neutralized, cost-effective, and effective strategy for POPs removal.

MOF derived MnFeOX supported on carbon cloth as electrochemical anode for peroxymonosulfate electro-activation and persistent organic pollutants degradation

In this work, metal–organic-framework (MOF) derived MnFeOX (MD-MnFeOX) was loaded onto carbon cloth (CC) formed MD-MnFeOX/CC anode. Subsequently, the ability of MD-MnFeOX/CC anode to electrochemically (EC) activate peroxymonosulfate (PMS) for the degradation of persistent organic pollutants was tested by introducing an electric field. The degradation results indicated that the MD-MnFeOX/CC/EC/PMS system had a degradation ability of 90.20 % for tetracycline (TC) within 20 min at a very low current density of 5 mA/cm2, which was significantly higher than that of CC/EC/PMS (53.75 %) and the reported conventional synthesized double transition metal oxide/EC/PMS electrocatalytic system. In addition, the system had excellent stability and low energy consumption (0.79 kWh/m3). The influencing factors of the degradation efficiency of the system were analyzed, and the degradation ability of the system in actual water bodies was tested. The results demonstrated that the system maintained a stable degradation efficiency in various influencing factors and actual water bodies, proving that the system could degrade organic pollutants in complex water bodies. Mechanistic analysis showed that singlet oxygen (1O2) played a dominant role in the MD-MnFeOX/CC/EC/PMS system. Finally, the pathway for TC degradation in this system was explored. This experiment provides an economically feasible method to improve the electrocatalytic performance of CC electrodes.

Enhanced pollutant photodegradation activity of graphitic carbon nitride on via bismuth oxyhalide graphene hybridization and the mechanism study

Addressing the degradation of persistent organic pollutants like Bisphenol A (BPA) and Rhodamine B (RhB) with a photocatalyst that is both cost-effective and environmentally friendly is a notable challenge. This...

Modulating the microenvironment of catalytic interface with functional groups for efficient photocatalytic degradation of persistent organic pollutants

The solar-driven photocatalytic degradation of persistent organic pollutants is considered as a promising water treatment approach.Nevertheless, the activity of photocatalytic degradation of pollutants is still limited by the rapid carrier recombination and sluggish oxygen mass transfer. Herein, we designed different functional groups modified WO3/R-MOF (MOF: MIL-125-Ti, R = NH2, C5H11, C5F11) heterojunction to overcome the aforementioned limitations. Among them, WO3/C5F11-MOF exhibited an excellent degradation efficiency of 91.6 % for 4-chlorophenol pollutants, which was seven and two times higher than that of WO3/NH2-MOF and WO3/C5H11-MOF, respectively. The WO3/C5H11-MOF and WO3/C5F11-MOF exhibited hydrophobic and formed microscopic triphase interface, which increased oxygen transfer. Furthermore, strong electron-withdrawing property of fluorine in the C5F11- ligand generated electron-deficient regions, increasing the transfer rate of photo-generated electrons and prolonging the relaxation time of electrons. Thus, hydrophobic WO3/C5F11-MOF not only regulates the catalytic interface microenvironment, but also effectively inhibits the recombination of photo-generated carrier. This study provides an efficient strategy to achieve excellent photocatalytic activity via interfacial engineering.

Boosted micropollutant removal over urchin-like structured hydroxyapatite-incorporated nickel magnetite catalyst via peroxydisulfate activation

In this work, urchin-like structured hydroxyapatite-incorporated nickel magnetite (NiFe3O4/UHdA) microspheres were developed for the efficient removal of micropollutants (MPs) via peroxydisulfate (PDS) activation. The prepared NiFe3O4/UHdA degraded 99.0 % of sulfamethoxazole (SMX) after 15 min in 2 mM PDS, having a first-order kinetic rate constant of 0.210 min−1. In addition, NiFe3O4/UHdA outperformed its counterparts, i.e., Fe3O4/UHdA and Ni/UHdA, by giving rise to corresponding 3.6-fold and 8.6-fold enhancements in the SMX removal rate. The outstanding catalytic performance can be ascribed to (1) the urchin-like mesoporous structure with a large specific surface area and (2) the remarkable synergistic effect caused by the redox cycle of Ni3+/Ni2+ and Fe2+/Fe3+ that enhances multipath electron transfers on the surface of NiFe3O4/UHdA to produce more reactive oxygen species. Moreover, the effects of several reaction parameters, in this case the initial solution pH, PDS dosage, SMX concentration, catalyst loading, co-existing MPs and humic acid level on the catalytic performance of the NiFe3O4/UHdA + PDS system were systematically investigated and discussed in detail. The plausible catalytic mechanisms in the NiFe3O4/UHdA + PDS system were revealed via scavenging experiments and electron paramagnetic resonance analysis, which indicated a radical (•OH and SO4•−) as the major pathway and a nonradical (1O2) as the minor pathway for SMX degradation. Furthermore, NiFe3O4/UHdA exhibited fantastic magnetically separation and retained good catalytic activity with a low leached ion concentration during the performance of four cycles. Overall, the prepared NiFe3O4/UHdA with outstanding PDS activation could be a promising choice for the degradation of persistent organic pollutants from wastewater.

Reconfigurable self-assembly of photocatalytic magnetic microrobots for water purification

The development of artificial small-scale robotic swarms with nature-mimicking collective behaviors represents the frontier of research in robotics. While microrobot swarming under magnetic manipulation has been extensively explored, light-induced self-organization of micro- and nanorobots is still challenging. This study demonstrates the interaction-controlled, reconfigurable, reversible, and active self-assembly of TiO2/α-Fe2O3 microrobots, consisting of peanut-shaped α-Fe2O3 (hematite) microparticles synthesized by a hydrothermal method and covered with a thin layer of TiO2 by atomic layer deposition (ALD). Due to their photocatalytic and ferromagnetic properties, microrobots autonomously move in water under light irradiation, while a magnetic field precisely controls their direction. In the presence of H2O2 fuel, concentration gradients around the illuminated microrobots result in mutual attraction by phoretic interactions, inducing their spontaneous organization into self-propelled clusters. In the dark, clusters reversibly reconfigure into microchains where microrobots are aligned due to magnetic dipole-dipole interactions. Microrobots’ active motion and photocatalytic properties were investigated for water remediation from pesticides, obtaining the rapid degradation of the extensively used, persistent, and hazardous herbicide 2,4-Dichlorophenoxyacetic acid (2,4D). This study potentially impacts the realization of future intelligent adaptive metamachines and the application of light-powered self-propelled micro- and nanomotors toward the degradation of persistent organic pollutants (POPs) or micro- and nanoplastics.

Insights into hydrangea-like NiCo2S4 activating peroxymonosulfate for efficient degradation of atrazine

Developing a highly efficient heterogeneous catalyst for activating peroxymonosulfate (PMS) in the degradation of persistent organic pollutants (POPs) remains a challenge, and transition bimetallic sulfide is considered a promising candidate. Herein, a hydrangea-like NiCo2S4 was designed for activating PMS in the removal of a typical POP (atrazine, ATZ), and the activation mechanism of the catalyst was elucidated. The hydrangea-like NiCo2S4 was successfully synthesized through sulfide ion-exchange with its oxide counterpart (NiCo2O4), showing much more excellent catalytic performance in activating PMS than NiCo2O4 for the degradation of ATZ. The ATZ (46 μM) degradation efficiency (RD) in the NiCo2S4/PMS system (40 mg L−1 catalyst and 0.4 mM PMS) achieves nearly 100 % within 10 min with an apparent rate constant (k) of 0.583 min−1, superior to those of NiCo2O4/PMS system with values of RD = 26.7 % and k = 0.033 min−1. The role of sulfur species was uncovered and the origin of the exceptional catalytic performance of NiCo2S4 was disclosed through various techniques. The results demonstrated that sulfur species not only accelerated electron transfer but also promoted the regeneration of reactive sites by facilitating the conversion of Co3+/Ni3+ to Co2+/Ni2+. More reactive oxygen species (ROSs), including sulfate radical (SO4•−), hydroxyl radical (•OH), superoxide radical (O2•−) and singlet oxygen (1O2) were produced for attacking ATZ molecules, leading to their degradation into the intermediates with reduced toxicity.

Boron Bifunctional Catalysts for Rapid Degradation of Persistent Organic Pollutants in a Metal-Free Electro-Fenton Process: O2 and H2O2 Activation Process.

Metals usually served as the active sites of the heterogeneous bifunctional electro-Fenton reaction, which faced the challenge of poor stability under acidic or even neutral conditions. Exploring a metal-free heterogeneous bifunctional electro-Fenton catalyst can effectively solve the above problems. In this work, a stable metal-free heterogeneous bifunctional boron-modified porous carbon catalyst (BTA-1000) was synthesized. For the BTA-1000 catalyst, the yield of H2O2 (294 mg/L) significantly increased. The degradation rate of phenol by BTA-1000 (0.242 min-1) increased by an order of magnitude, compared with the porous carbon catalyst (0.0105 min-1). The BTA catalyst could rapidly degrade industrial dye wastewater, and its specific energy consumption was 5.52 kW h kg-1 COD-1, lower than that in previous reports (6.38-7.4 kW h kg-1 COD-1). DFT and XPS revealed that C═O and -BC2O groups jointly promoted the generation of H2O2, and the -BCO2 group played dominant roles in the generation of •OH because the oxygen atom near the electron-giving groups (-BCO2 group) facilitated the formation of hydrogen bond and H2O2 adsorption. This work gained deep insights into the reaction mechanism of the boron-modified porous carbon catalyst, which helped to guide the development of metal-free heterogeneous bifunctional electro-Fenton catalysts.

Unveiling the novel role of ryegrass rhizospheric metabolites in benzo[a]pyrene biodegradation

Rhizoremediation is a promising remediation technology for the removal of soil persistent organic pollutants (POPs), especially benzo[a]pyrene (BaP). However, our understanding of the associations among rhizospheric soil metabolites, functional microorganisms, and POPs degradation in different plant growth stages is limited. We combined stable-isotope probing (SIP), high-throughput sequencing, and metabolomics to analyze changes in rhizospheric soil metabolites, functional microbes, and BaP biodegradation in the early growth stages (tillering, jointing) and later stage (booting) of ryegrass. Microbial community structures differed significantly among growth stages. Metabolisms such as benzenoids and carboxylic acids tended to be enriched in the early growth stage, while lipids and organic heterocyclic compounds dominated in the later stage. From SIP, eight BaP-degrading microbes were identified, and most of which such as Ilumatobacter and Singulisphaera were first linked with BaP biodegradation. Notably, the relationship between the differential metabolites and BaP degradation efficiency further suggested that BaP-degrading microbes might metabolize BaP directly to produce benzenoid metabolites (3-hydroxybenzo[a]pyrene), or utilize benzenoids (phyllodulcin) to stimulate the co-metabolism of BaP in early growth stage; some lipids and organic acids, e.g. 1-aminocyclopropane-1-carboxylic acid, might provide nutrients for the degraders to promote BaP metabolism in later stage. Accordingly, we determined that certain rhizospheric metabolites might regulate the rhizospheric microbial communities at different growth stages, and shift the composition and diversity of BaP-degrading bacteria, thereby enhancing in situ BaP degradation. Our study sheds light on POPs rhizoremediation mechanisms in petroleum-contaminated soils.