Biodegradation Mechanism Research Articles

Microbial remediation of insensitive munitions compounds and their transformation products: from biodegradation mechanisms to engineered strategies

Microbial remediation of insensitive munitions compounds and their transformation products: from biodegradation mechanisms to engineered strategies

State of the art on biodegradability of bio-based plastics containing polylactic acid

Bio-based plastics represent an opportunity to reduce the impact of petroleum-based plastics on the environment, leading to harmful effects on both terrestrial and marine ecosystems. Nevertheless, the plant origin of bio-based plastics does not necessarily imply better management of their end of life. However, when recycling is impossible, the biological degradation of bio-based plastics would be an effective method to reduce their environmental impact. Polylactic acid (PLA) is one of the most produced biopolymers currently among the bio-based plastics already developed for several years. Thus, the objective of this article is to provide a state of the art on the biodegradation of bio-based plastics based on PLA. In particular, the microorganisms catalyzing the different biochemical reactions and the main biodegradation mechanisms are reviewed according to aerobic and anaerobic conditions. Moreover, different microorganisms involved in the degradation of PLA are summarized. Furthermore, a special attention is paid to the analytical methods to evaluate the biodegradation of polylactic acid and to the different existing biodegradation test methods, because this subject has rarely been reviewed in the literature. In the end, several promising topics for the future research are proposed, such as enzyme engineering technology as a recently emerging method for PLA degradation and a new common testing method to collect as much data as possible on the biodegradability to compare different studies.

A Comparative Review on Biodegradation of Poly(Lactic Acid) in Soil, Compost, Water, and Wastewater Environments: Incorporating Mathematical Modeling Perspectives

As the demand for environmentally friendly materials continues to rise, poly(lactic acid) (PLA) has emerged as a promising alternative to traditional plastics. The present review offers a comprehensive analysis of the biodegradation behavior of PLA in diverse environmental settings, with a specific focus on soil, compost, water, and wastewater environments. The review presents an in-depth comparison of the degradation pathways and kinetics of PLA from 1990 to 2024. As the presence of different microorganisms in diverse environments can affect the mechanism and rate of biodegradation, it should be considered with comprehensive comparisons. It is shown that the mechanism of PLA biodegradation in soil and compost is that of enzymatic degradation, while the dominant mechanisms of degradation in water and wastewater are hydrolysis and biofilm formation, respectively. PLA reveals a sequence of biodegradation rates, with compost showing the fastest degradation, followed by soil, wastewater, accelerated landfill environments, and water environments, in descending order. In addition, mathematical models of PLA degradation were reviewed here. Ultimately, the review contributes to a broader understanding of the ecological impact of PLA, facilitating informed decision-making toward a more sustainable future.

Comprehensive Study on Endocrine Disruptor Removal from Wastewater Using Different Microalgae Species

The concentration of endocrine disruptor compounds (EDCs) in wastewater is increasing, posing significant risks to living organisms. This study concerns the simultaneous degradation of a variety of EDCs from wastewater, including methylparaben (MeP), propylparaben (PrP), butylparaben (BuP), benzophenone (BP), bisphenol A (BPA), and estrone (E), in the presence of the microalgae Scenedesmus sp. or Chlorella vulgaris. The potential for the abiotic removal of these EDCs and their underlying degradation mechanisms were also studied. The presence of microalgae significantly enhanced the degradation of parabens, achieving complete removal within 7 days, primarily through the mechanism of biodegradation. BPA removal was also improved by microalgae, reaching 82% and 90% within 7 days with Scenedesmus sp. and C. vulgaris, respectively. BP degradation was predominantly abiotic, accomplishing 95% removal in 7 days. E degradation was mainly abiotic, achieving approximately 40% within 7 days, with a notable contribution from a biodegradation mechanism in the later stages, accounting for 27% and 40% of the final total removal in the presence of Scenedesmus sp. and C. vulgaris, respectively. This study provides insights into the mechanisms of EDC degradation by microalgae, highlighting the potential of Scenedesmus sp. and C. vulgaris to remove a mixture of EDCs from wastewater.

Biochemical and molecular mechanisms of Rhodococcus rhodochrous IITR131 for polyethylene terephthalate degradation.

To isolate polyethylene terephthalate (PET) degrading bacteria and elucidate the underlying mechanisms of PET biodegradation through biochemical and genome analysis. A Rhodococcus rhodochrous IITR131 was found to degrade PET. Strain IITR131 genome revealed metabolic versatility of the bacterium and had the ability to form biofilm on PET sheet resulting in the cracks, abrasions, and degradation. IITR131 showed a reduction of 19.7%, exhibiting a half-life of 189.9 d of 0.1 mm PET film in 60 d and formed metabolites bis(2-hydroxyethyl) terephthalate (BHET), terephthalic acid (TPA), and benzoic acid (BA). The draft genome of 5.9 Mb of IITR131 revealed that this bacterium has plethora of genes such as terephthalate 1, 2 dioxygenase, carboxylesterase that together constituted a complete pathway for PET degradation. Moreover, strain IITR131 was found to have a variety of genes encoding for enzymes for the metabolism of several plastic polymers, xenobiotics including chloroalkanes, and polycyclic aromatic hydrocarbons. A R. rhodochrous IITR131 demonstrated significant potential in the biodegradation of PET. The comprehensive genomic and metabolic analyses further elucidated the molecular pathway involved in PET degradation, enhancing our understanding of the mechanisms underlying microbial PET biodegradation. These findings underscore the applicability of R. rhodochrous IITR131 in biotechnological approaches for mitigating plastic pollution.

Impact of adaptation time on lincomycin removal in riverbank filtration: A long-term sand column study.

Riverbank filtration (RBF) is an effective pretreatment technology for drinking water, removing organic micropollutants (OMPs) mainly through biodegradation. Despite documented improvements in OMP removal with extended adaptation time, the mechanisms remain poorly understood. This study assessed the removal of 128 OMPs over 82 d in a simulated RBF system, identified those with improved removal, and analyzed their properties. Additionally, microbial community shifts after 400 d of lincomycin exposure were studied to understand the underlying mechanisms. We found that the removal efficiencies of 24 OMPs, including lincomycin and fluconazole, improved by 3-77 % over 82 d while being positively correlated with the presence of tertiary amides and secondary sulfonamides. Lincomycin removal efficiency rose from 20 % to 95 % over 68 days and stayed high. We identified eight potential degradation products of lincomycin, occurring primarily via hydroxylation, N-demethylation, and amide hydrolysis. Additionally, lincomycin notably increased the abundances of specific antibiotic-resistant bacteria (e.g., Thiobacillus, 8.3-fold) and ammonia-oxidizing archaea (e.g., Nitrososphaera, 46.8-fold). The β-lactam resistance gene in Thiobacillus and the amoA gene in Nitrososphaera may enhance lincomycin's removal by promoting its hydrolysis and hydroxylation. Overall, this study provides insights into OMP biodegradation mechanisms and the impact of ng/L levels of lincomycin on microbial communities.

Removal of BPA by Pseudomonas asiatica P1: Synergistic response mechanism of toxicity resistance and biodegradation

Bisphenol A (BPA) is a globally concerning toxic pollutant, and microbial degradation is considered an effective method to treat BPA contamination. However, the inherent microbial toxicity of BPA is often overlooked, particularly the microbial mechanisms of resistance and detoxification against BPA. This study found that under the toxic stress of BPA, cbb3-type cytochrome c oxidase (cbb3-Cox) in the cells of Pseudomonas asiatica P1 (P. asiatica P1) was the first to resist the toxicity. Genes such as ccoNOQPG showed significant upregulation with an average log2FC value of 3.56. Subsequently, genes that are related to metal ion binding, transport, and DNA repair were upregulated in the middle to later phase, which enhanced the metabolic functions of the strains and induced strain mutations to assist P. asiatica P1 in resisting the BPA toxicity. Meanwhile, three potential BPA degradation genes were identified, among which sdrP1 was crucial to the BPA degradation and detoxification. After genetic recombination, sdrP1 achieved a degradation rate of 92.52 % for BPA. Furthermore, through various methods such as alkyl interactions, sdrP1 exhibited oxidation and demethylation to form lower toxic intermediate products and complete the biological detoxification of BPA. This study provides a systematic analysis of the toxicity resistance, biodegradation, and detoxification processes in bacterial BPA removal, refines the mechanism of BPA biodegradation and contributes to a more comprehensive and systematic understanding of the overall process of microbial removal of toxic pollutants.

Optimization of anthracene biodegradation by indigenous Trichoderma lixii and Talaromyces pinophilus using response surface methodology

Two indigenous fungal strains, Trichoderma lixii FLU1 (TlFLU1) and Talaromyces pinophilus FLU12 (TpFLU12) showed potential to biodegrade anthracene. Response Surface Methodology (RSM) employing Box-Behnken Design (BBD) and Central Composite Design (CCD) methods optimized crucial physicochemical parameters like pH, temperature, biomass, substrate concentration and media composition. BBD maximized anthracene biodegradation efficiency by predicting 98.7–103.2 %. Analysis of Variance confirmed the model's accuracy with a significant F-value of 51.0 at p<0.0001 while the quadratic regression model showed a high R² value 0.9808. CCD predicted 100 % degradation efficiency which were validated for TlFLU1 and TpFLU12 respectively on day 8 and 12 at pH 4 and 5, temperatures 30°C and 25°C, with 20 mm biomass size and 200 mg/L anthracene. 9,10-anthraquinone and phthalic acid were detected as metabolites formed during the anthracene degradation by TlFLU1 and TpFLU12 after validation of the optimization process. Acute toxicity tests showed that the degradation media toxicity reduced as evidenced by increased in survival rate (log CFU/mL) of Vibrio parahaemolyticus after 6 h exposure. Despite reduced toxicity, both strains were classified as harmful based on effective concentration (EC50) and toxicity unit (TU) (20.92±1.32 mg/L and 4.78 % for TlFLU1 and 35.29±1.55 mg/L and 2.83 % for TpFLU12). This systematic optimization approach supported by robust statistical analyses and a deep exploration of biodegradation mechanisms holds the promise of more efficient and sustainable methods for remediating PAH-contaminated environments.

Recent Progress in Biomedical Scaffold Fabricated via Electrospinning: Design, Fabrication and Tissue Engineering Application

AbstractElectrospinning is a significant manufacturing strategy to create micro/nanofiber platforms that can be considered a biomedical scaffold for tissue engineering repair and regeneration. In recent years researchers have continuously broadened the equipment design and materials development of electrospinning nanofiber platforms (ENPs), which have evolved from single‐needle to multi‐needle for creating 3D ENPs, to diversify their application including the drugs/cell/growth factors release, anti‐bacterial and anti‐inflammatory, hemostasis, wound healing, and tissue repair and regeneration. Herein, multifunctional ENPs scaffold with bioactive polymer fabricated via electrospinning in terms of novel material design, construction of various structures, and various requirements in different tissue engineering regeneration are reviewed. Furthermore, this review delves into recent advancements in tissue repair facilitated by ENPs, highlighting their effectiveness and versatility across various tissue types such as bone, cartilage, tendons, cardiac tissue, and nerves. The discussion comprehensively addresses ongoing challenges in material selection, biodegradation mechanisms, bioactivation strategies, and manufacturing techniques specific to tissue repair applications. Moreover, the review outlines potential future research avenues aimed at enhancing ENPs‐based approaches in tissue engineering. This in‐depth analysis aims to provide nuanced insights and technical recommendations to propel the field of ENPs forward in tissue repair and regeneration.

Deciphering the biodegradation mechanism of 3,6-dichlorocarbazole using a novel isolate for its implication in bioaugmentation

This study reported a newly isolated strain, Streptomyces sp. FW-32, which showed good ability to degrade 3,6-dichlorocarbazole (3,6-DCCZ). The maximum degradation efficiency of 3,6-DCCZ reached 86.78 % within 5 d at pH of 7.6, glucose concentration of 5.0 g/L, temperature of 33 °C, and 3,6-DCCZ initial concentration of 1.0 mg/L. In total, five biodegradation products were detected, indicating that 3,6-DCCZ was mainly transformed via dechlorination, oxidation, and aromatic ring cleavage. Proteomic analysis suggested that haloacid dehalogenase, glutathione S-transferase family protein, cytochrome P450s, pentachlorophenol monooxygenase, hydroxylase, and several dioxygenases were involved in 3,6-DCCZ biotransformation. Glutathione peroxidase, catalases, catalase − peroxidase, thioredoxin, thioredoxin reductase, and thioredoxin-dependent peroxiredoxin were induced to resist 3,6-DCCZ stress. Molecular docking revealed that 3,6-DCCZ exhibited an affinity for the potential proteins involved in 3,6-DCCZ biodegradation and stress response. Furthermore, the biotreatment of 3,6-DCCZ with the strain FW-32 might have contributed to the reduction in the aquatic toxicity of 3,6-DCCZ. The strain FW-32 efficiently synergized with certain indigenous microorganisms, consequently accelerating the removal of 3,6-DCCZ from the water–sediment system. Overall, these findings shed a new light on the mechanisms underlying the microbial transformation of 3,6-DCCZ, suggesting that Streptomyces sp. FW-32 exhibits considerable potential for the bioaugmentation of 3,6-DCCZ-contaminated aquatic environments.

(Invited) Bio-Inspired Method for Degrading Carbon Nanotubes

Carbon nanotubes (CNTs) have shown promise for biological and medical applications due to their biocompatibility, superior electrical conductivity, unique optical properties, and chemical modifiability. For instance, our research group has developed bright near-infrared imaging probe by using oxygen-doped CNTs, so far [1-3]. On the other hand, the adverse effects of CNTs on the environment and human health have recently become a concern. Since CNTs are made of stable graphite, their potential for accumulation in the environment and in living organisms has been discussed. Elucidation of the biodegradation properties of CNTs is thus an essential issue in discussing their long-term safety. In recent years, there have been several reports on the biodegradability of CNTs, but the results differ from report to report, and many details are still unknown. Under these circumstances, we used a technique to measure the amount of CNTs taken up into cells using the near-infrared absorption property of CNTs, and clarified the biodegradation of CNTs in immune cells [4]. The rate of CNT biodegradation was directly proportional to the amount of reactive oxygen species generated, indicating that the biodegradation of CNTs in immune cells was due to reactive oxygen species [5]. Furthermore, the biodegradation mechanism of CNTs is thought to involve oxidation by hypochlorous acid generated during the enzymatic reaction. When hypochlorous acid compounds were mixed with CNT dispersion, we found that the CNT dispersion easily became transparent [5]. This degradation method is applicable to single-walled carbon nanotubes, multi-walled carbon nanotubes, and even graphene [6,7]. We are currently working on international standardization activities for this method.[1] Y. Iizumi, M. Yudasaka, J. Kim, H. Sakakita, T. Takeuchi, T. Okazaki, Oxygen-doped carbon nanotubes for near-infrared fluorescent labels and imaging probes, Sci. Rep., 8, 6272 (2018).[2] T. Takeuchi, Y. Iizumi, M. Yudasaka, S. K. Kondoh, T. Okazaki, Characterization and biodistribution analysis of oxygen-doped single-walled carbon nanotubes used as in vivo fluorescence imaging probes, Bioconjugate Chem., 30, 1323−1330 (2019). (Cover Article)[3] K. Kojima, Y. Iizumi, M. Zhang, T. Okazaki, Streptavidin-conjugated oxygen-doped single-walled carbon nanotubes as near-infrared labels for immunoassays, Langmuir, 38, 1509-1513 (2022).[4] M. Yang, M. Zhang, H. Nakajima, M. Yudasaka, S. Iijima, T. Okazaki, Time-Dependent Degradation of Carbon Nanotubes Correlates with Decreased Reactive Oxygen Species Generation In Macrophages, Int. J. Nanomedicine, 14, 2797-2807 (2019).[5] M. Zhang, Y. Deng, M. Yang, H. Nakajima, M. Yudasaka, S. Iijima, T. Okazaki, A Simple Method for Removal of Carbon Nanomaterials from Wastewater Using Hypochlorite, Sci. Rep. 9, 1284 (2019).[6] M. Zhang, M. Yang, H. Nakajima, M. Yudasaka, S. Iijima, T. Okazaki, Diameter-Dependent Degradation of 11 Types of Carbon Nanotubes: Safety Implications, ACS Appl. Nano Mater., 2, 4293-4301 (2019).[7] M. Zhang, M. Yang, Y. Okigawa, T. Yamada, H. Nakajima, Y. Iizumi, T. Okazaki, Patterning of graphene using wet etching with hypochlorite and UV light, Sci. Rep., 12, 1541 (2022).

Microbial Diversity and Biodegradation Mechanism of Microorganisms in the Dingtao M2 Tomb.

The Dingtao M2 tomb, the largest and best-preserved imperial "Huangchangticou" tomb in China, holds great significance for its conservation. Currently, varying degrees of microbial degradation are occurring on the surfaces of the M2 tomb. This study aimed to determine the microbial diversity of the M2 tomb and its surrounding environment during July 2021 and August 2022. High-throughput metagenomic sequencing revealed that the dominant fungus on the surface of the tomb chamber was Dacrymyces stillatus (DTT1) in July 2021, which changed to Talaromyces pinophilus (DTT2) in August 2022. Enzymatic activities for cellulose and lignin degradation suggested that DTT1 has high levels of manganese peroxidase, lignin peroxidase, laccase, and cellulase. The wood of the tomb contained higher levels of Fe2+ and Ca2+, and experiments with different concentration gradients of these ions in the culture medium revealed that DTT1 exhibited greater activity of cellulose and lignin degradation in environments with higher concentrations of Fe2+ and Ca2+. DTT2 degraded both cellulose and lignin. Lastly, a laboratory plate inhibition experiment demonstrated that isothiazolinone fungicide had a significant fungicidal effect on these two dominant fungi. This study provides valuable data and a theoretical basis for the preservation of the M2 tomb and other wooden cultural relics.

The Mechanism of Aniline Blue Degradation by Short-Chain Dehydrogenase (SDRz) in Comamonas testosteroni.

Dye wastewater pollution, particularly from persistent and toxic polycyclic organic pollutants, such as aniline blue, poses a significant environmental challenge. Aniline blue, a triphenylmethane dye widely used in the textile, leather, paper, and pharmaceutical industries, is notoriously difficult to treat owing to its complex structure and potential for bioaccumulation. In this study, we explored the capacity of Comamonas testosteroni (CT1) to efficiently degrade aniline blue, focusing on the underlying enzymatic mechanisms and degradation pathways. Through prokaryotic transcriptome analysis, we identified a significantly upregulated short-chain dehydrogenase (SDRz) gene (log2FC = 2.11, p < 0.05) that plays a crucial role in the degradation process. The SDRz enzyme possessed highly conserved motifs and a typical short-chain dehydrogenase structure. Functional validation using an SDRz-knockout strain (CT-ΔSDRz) and an SDRz-expressioning strains (E-SDRz) confirmed that SDRz is essential for aniline blue degradation. The knockout strain CT-ΔSDRz exhibited a 1.27-fold reduction in the degradation efficiency, compared to CT1 strain after 12 h; while the expression strain E-SDRz showed a 1.24-fold increase compared to Escherichia coli DH5α after 12 h. Recombinant SDRz (rSDRz) was successfully produced, showing significant enzymatic activity (1.267 ± 0.04 mmol·L-1·min-1 protein), with kinetic parameters Vmax = 2.870 ± 0.0156 mmol·L⁻1·min⁻1 protein and Km = 1.805 ± 0.0128 mM·mL-1. Under optimal conditions, the rSDRz achieved a degradation efficiency of 62.17% for aniline blue. Gas chromatography-mass spectrometry (GC-MS) analysis identified several intermediate metabolites in the degradation pathway, including benzeneacetaldehyde, a, a-diphenyl, 2-amino-4-methylbenzophenone, benzene, 1-dimethylamino-4-phenylmethyl, benzenesulfonic acid, methyl ester, further elucidating the biodegradation mechanism. These findings highlight SDRz as a critical enzyme in the biodegradation of aniline blue, offering valuable insights and a robust theoretical foundation for developing advanced bioremediation strategies to address dye wastewater pollution.

The biochemical mechanisms of plastic biodegradation.

Since the invention of the first synthetic plastic, an estimated 12 billion metric tons of plastics have been manufactured, 70% of which was produced in the last 20 years. Plastic waste is placing new selective pressures on humans and the organisms we depend on, yet it also places new pressures on microorganisms as they compete to exploit this new and growing source of carbon. The limited efficacy of traditional recycling methods on plastic waste, which can leach into the environment at low purity and concentration, indicates the utility of this evolving metabolic activity. This review will categorize and discuss the probable metabolic routes for each industrially relevant plastic, rank the most effective biodegraders for each plastic by harmonizing and reinterpreting prior literature, and explain the experimental techniques most often used in plastic biodegradation research, thus providing a comprehensive resource for researchers investigating and engineering plastic biodegradation.

Bacterial Degradation of Petroleum Hydrocarbons in Saudi Arabia.

The Kingdom of Saudi Arabia (KSA) is the leading oil-exploring and -exploiting country in the world. As a result, contamination of the environment by petroleum products (mainly hydrocarbons) is common, necessitating strategies for their removal from the environment. Much work has been conducted on bacterial degradation of hydrocarbons in the KSA. This review comprehensively analyzed 43 research investigation articles on bacterial hydrocarbon degradation, mainly polyaromatic hydrocarbons (PAHs) within the KSA. More than 30 different bacterial genera were identified that were capable of degrading simple and complex PAHs, including benzo[a]pyrene and coronene. Different strategies for selecting and isolating these bacterial strains and their advantages and disadvantages were highlighted. The review also discussed the origins of sample inocula and the contributions of various research groups to this field. PAH metabolites produced by these bacteria were presented, and biochemical pathways of PAH degradation were proposed. More importantly, research gaps that could enrich our understanding of petroleum product biodegradation mechanisms were highlighted. Overall, the information presented in this paper will serve as a baseline for further research on optimizing bioremediation strategies in all petroleum-contaminated environments.

Magnetic-resonance tomography post injection contouring plastic face different type fillers: features of the picture and signal characteristics

Purpose: to study the possibilities of magnetic resonance imaging in characterizing the soft tissues of the face after injection of various types of fillers.Material and methods. A group of 35 patients with a known cosmetic history was analyzed after combined (15) and non-combined (20) injection injections of fillers into various areas of the face. According to the anamnesis, with combined administration, hyaluronic acid (HA) + Ca hydroxyapatite (CaHA) was used in 10 cases, HA + L­polylactic acid (PLA) in 2 cases, HA + PLA + silicone in 1 case, HA + CaHA + silicone in 1 case, in 1 – HA + silicone. With non-combined administration, 16 patients received HA, 2 received Ca hydroxyapatite, one received L-polylactic acid, and one received polyacrylamide gel (PAGE).MRI of facial soft tissues was performed at different times after drug administration: HA – from 1 month. up to 4 years, CaHA – from 7 days to 1 year, PLA – from 1 to 8 months, silicone – 10–20 years, PAGE – after 6 months.The studies were carried out on 1.5 T MRI scanners, using T2-WI, T1-WI, STIR, DWI (b = 1000), T1-FS-WI, 3D-T2-WI sag. The location of the filler was determined, the type of filler was differentiated, and its location in relation to the surrounding structures was assessed.Results. Areas of the HA preparation were characterized by a hyperintense MR signal on T2-weighted images and Stir, isohypointense on T1-WI. Preparations based on CaHA and PLA were determined by isohypointense on T2, T1-WI, isohyperintense on Stir, iso- and isohyperintense on T1-FS-WI signal. Silicone demonstrated isohypointense signal with a hypointense capsule on T2-WI and Stir isointense on T1-WI; PAGE – isohyperintense on T2-WI and Stir, isohypointense on T1-WI with a hypointense capsule on all PIs.HA-based fillers were more clearly visualized on Stir and T2-WI. Preparations based on CaHA and PLA had identical signal characteristics on T2-WI, which made differential diagnosis difficult, but in a number of cases the following signal changes were detected on T1-FS-WI: iso- and isohypointense from CaHA, isohyperintense from PLA. The MRI picture varied depending on the timing, technique of administration and dilution of the drug.Conclusions. MRI allows you to visualize and differentiate the type of filler after injection contouring according to signal characteristics that depend on its chemical composition, timing of administration and mechanisms of biodegradation.

Removal mechanisms of pentachlorophenol in a horizontal-flow anaerobic immobilized biomass reactor (HAIB) inoculated with an indigenous estuarine sediment microbiota: adsorption and biodegradation processes.

Pentachlorophenol (PCP) is a highly toxic and carcinogenic compound with significant environmental impact, necessitating effective treatment technologies. This study evaluates PCP removal mechanisms, including adsorption and biodegradation, during the startup of a horizontal-flow anaerobic immobilized biomass reactor (HAIB), and examines the impact of PCP concentration on microbial diversity using denaturing gradient gel electrophoresis (DGGE). The primary mechanism for PCP removal in the HAIB was adsorption, effectively described by the Freundlich isotherm model. Adsorption efficiency ranged from 86 to 104% for PCP concentrations between 0.2 and 5.0mg/L, and 46% to 64% for concentrations between 0.098 and 0.05mg/L. Additionally, PCP degradation intermediates such as 2,3-DCP and 2,6-DCP were detected, indicating that biodegradation also occurred in the HAIB. Organic matter degradation averaged 81 ± 9%, and methane content in the biogas averaged 46 ± 9%, confirming the anaerobic process. No inhibition of microbial activity was observed due to PCP toxicity, even at a PCP load of 5mg PCP/g STV per day. While the archaeal community showed only slight changes, with similarity coefficients ranging from 88 to 95%, the bacterial community was significantly affected by PCP, with similarity coefficients ranging from 18 to 50%. Bacterial groups were responsible for the initial PCP degradation, while the archaeal community was involved in metabolizing the resulting byproducts. The use of indigenous inoculum from the Santos-São Vicente estuary demonstrated its potential for effective PCP removal. Polyurethane foam proved to be an effective support material, enhancing the adsorption process and reducing PCP toxicity to the microbial consortium. This study provides valuable insights into PCP adsorption and biodegradation mechanisms in HAIB, highlighting the effectiveness of indigenous inoculum and polyurethane foam for PCP removal.

Effective Treatment and Biodegradation Mechanism Analysis of Petroleum Hydrocarbon Wastewater by Immobilized Ochrobactrum sp. WY-4 on Iron-modified Biochar

Effective Treatment and Biodegradation Mechanism Analysis of Petroleum Hydrocarbon Wastewater by Immobilized Ochrobactrum sp. WY-4 on Iron-modified Biochar

Engineering Application of New Environmental Treatment Materials in Water Pollution Control

With the increasingly serious problem of water pollution, the application of new environmental governance materials in water pollution control has become a research hotspot. This paper systematically discusses the engineering applications of a variety of novel environmental governance materials in water pollution control, including nanomaterials, biomaterials and composites, and analyzes in detail the mechanisms of physical adsorption, chemical degradation, biodegradation and photocatalysis of these materials in practical applications. In addition, the practical effects of novel materials in water pollution control are demonstrated through cases of river training, industrial wastewater treatment and drinking water purification. Although these materials show remarkable pollutant removal ability, they still face challenges in practical applications such as material stability, economic cost and environmental safety. The paper concludes with an outlook on the future development direction of new environmental control materials and the need for further research, with a view to providing more effective solutions for water pollution control.

Unexpected increase in microalgal removal of doxylamine induced by bicarbonate addition: synergistic chem-/bio-degradation mechanisms

Microalgae-based approaches serve as promising methods for the remediation of pharmaceutical contaminants (PCs) compared to conventional wastewater treatment processes. However, how to decrease hydraulic retention times of the microalgal system currently has been one of the main bottlenecks. This study constructed an unexpected synergistic extra-chemical/intra-biological degradation system by adding 5.95 mM bicarbonate to the microalgal system, which achieved complete removal (100%) of a representative PC, doxylamine (DOX) in 96 h, compared to that 192 h in the control. Removal capacities and mass balance analyses demonstrated that biodegradation rate per unit microalgal density was significantly increased by 207%. Further analyses using transcriptomic, enzymatic inhibiting tests, and high-resolution mass spectrometry revealed that after addition of bicarbonate for metabolism of DOX, a hydrolase (CYP97C1) and a primary amine oxidase (TynA) can transform DOX into doxylamine N-oxide and an intermediate (C15H17NO2) with a m/z of 244.1335. Meanwhile, bicarbonate reacted with microalgae-excreted hydrogen peroxide to form more oxidative radicals such as superoxide and hydroxyl radicals extracellularly, which promised the extracellular degradation of DOX according to the oxidative radical inhibiting tests. Further investigation showed addiing bicarbonate to the microalgal system improved the removal rate of 17 PCs by up to 500.8%. Therefore, this study not only developed an approach to enhance treatment efficiencies of diverse PCs by microalgae within a shorter time, but also carried unique mechanistic insights into the underlying principles.