Self-purification of actual wastewater via microbial-synergy driving of catalyst-surface microelectronic field: A pilot-scale study.

High energy consumption is impedimental for eliminating refractory organics in wastewater by current technologies. Herein, we develop an efficient self-purification process for actual non-biodegradable dyeing wastewater at pilot scale, using N-doped graphene-like (CN) complexed Cu-Al2O3 supported Al2O3 ceramics (HCLL-S8-M) fixed-bed reactor without additional input. About 36% chemical oxygen demand removal was achieved within 20 min empty bed retention time and maintained stability for almost one year. The HCLL-S8-M structure feature and its interface on microbial community structure, functions, and metabolic pathways were analyzed by density-functional theory calculation, X-ray photoelectron spectroscopy, multiomics analysis of metagenome, macrotranscriptome and macroproteome. On the surface of HCLL-S8-M, a strong microelectronic field (MEF) was formed by the electron-rich/poor area due to Cu-π interaction from the complexation between phenolic hydroxy of CN and Cu species, driving the electrons of the adsorbed dye pollutants to the microorganisms through extracellular polymeric substance and the direct transfer of extracellular electrons, causing their degradation into CO2 and intermediates, which was degraded partly via intracellular metabolism. The lower energy feeding for the microbiome produced less adenosine triphosphate, resulting in little sludge throughout reaction. The MEF from electronic polarization is greatly potential to develop low-energy wastewater treatment technology.

Enhanced purification of kitchen-oil wastewater driven synergistically by surface microelectric fields and microorganisms.

The stable structure and toxic effect of refractory organic pollutants in wastewater lead to the problem of high energy consumption in water treatment technology. Herein, we propose a synergistic purification of refractory wastewater driven by microorganisms and surface microelectric fields (SMEF) over a dual-reaction-center (DRC) catalyst HCLL-S8-M prepared by an in situ growth method of carbon nitride on the Cu-Al2O3 surface. Characterization techniques demonstrate the successful construction of SMEF with strong electrostatic force over HCLL-S8-M based on cation-π interactions between metal copper ions and carbon nitride rings. With the catalyst as the core filler, an innovative fixed bed bioreactor is constructed to purify the actual kitchen-oil wastewater. The removal efficiency of the wastewater even with a very low biodegradability (BOD5/COD = 0.33) can reach 60% after passing through this bioreactor. An innovative reaction mechanism is revealed for the first time that under the condition of a small amount of biodegradable organic matter, the SMEF induces the enrichment of electric active microorganisms (Desulfobulbus and Geobacter) in the wastewater, accelerates the interspecies electron transfer of intertrophic metabolism with the biodegradable bacteria through the extracellular electron transfer mechanism such as cytochrome C and self-secreted electron shuttle. The electrons of the refractory organic pollutants adsorbed on the surface of the catalyst are delocalized by the SMEF, which can be directly utilized by microorganisms through EPS conduction. The SMEF generated by electron polarization can maximize the utilization of pollutants and microorganisms in wastewater and further enhance degradation without adding any external energy, which is of great significance to the development of water self-purification technology.

In vitro and in vivo assessments of the genotoxic potential of 3-chloroallyl alcohol.

3-Chloroallyl alcohol (3-CAA) can be found in the environment following the application of plant protection products. 3-CAA is formed in groundwater following the injection of 1,3-dichloropropene, a fumigant used to control nematodes. 3-CAA is also formed, in leafy crops, as a glycoside conjugate following application of the herbicide, clethodim. Human exposure may occur from groundwater used as drinking water or through dietary consumption. To characterize 3-CAA's potential to cause genotoxicity in mammals, in vitro and in vivo studies were conducted. 3-CAA was negative in an Ames test and positive in a mouse lymphoma forward mutation assay. 3-CAA was negative in an acute in vivo CD-1 mouse bone marrow micronucleus assay when administered up to a dose level of 125 mg/kg/day for two consecutive days. In a combined gene mutation assay and erythrocyte micronucleus assay, using transgenic Big Blue® Fischer 344 rats, 3-CAA was administered via drinking water at targeted dose levels of 0, 10, 30, and 100 mg/kg/day for 29 days. Peripheral blood samples, collected at the end of treatment, were analyzed for micronucleus induction in reticulocytes using flow cytometry. Liver and bone marrow samples, collected 2 days after the termination of the treatment, were analyzed for the induction of mutations at the cII locus. 3-CAA did not induce an increase in mutant frequency or micronuclei under the experimental conditions. In conclusion, the mutagenic response observed in the in vitro mouse lymphoma assay is not confirmed in the whole animal. 3-CAA is not considered to pose a mutagenic risk.

Towards best use and regulatory acceptance of generic physiologically based kinetic (PBK) models for in vitro-to-in vivo extrapolation (IVIVE) in chemical risk assessment.

With an increasing need to incorporate new approach methodologies (NAMs) in chemical risk assessment and the concomitant need to phase out animal testing, the interpretation of in vitro assay readouts for quantitative hazard characterisation becomes more important. Physiologically based kinetic (PBK) models, which simulate the fate of chemicals in tissues of the body, play an essential role in extrapolating in vitro effect concentrations to in vivo bioequivalent exposures. As PBK-based testing approaches evolve, it will become essential to standardise PBK modelling approaches towards a consensus approach that can be used in quantitative in vitro-to-in vivo extrapolation (QIVIVE) studies for regulatory chemical risk assessment based on in vitro assays. Based on results of an ECETOC expert workshop, steps are recommended that can improve regulatory adoption: (1) define context and implementation, taking into consideration model complexity for building fit-for-purpose PBK models, (2) harmonise physiological input parameters and their distribution and define criteria for quality chemical-specific parameters, especially in the absence of in vivo data, (3) apply Good Modelling Practices (GMP) to achieve transparency and design a stepwise approach for PBK model development for risk assessors, (4) evaluate model predictions using alternatives to in vivo PK data including read-across approaches, (5) use case studies to facilitate discussions between modellers and regulators of chemical risk assessment. Proof-of-concepts of generic PBK modelling approaches are published in the scientific literature at an increasing rate. Working on the previously proposed steps is, therefore, needed to gain confidence in PBK modelling approaches for regulatory use.

Investigation of potential early key events and mode of action for 1,2-dichloroethane-induced mammary tumors in female rats.

1,2-dichloroethane (DCE or EDC) is a chlorinated hydrocarbon used as a chemical intermediate, including in the synthesis of polyvinyl chloride. Although DCE has induced tumors in both rats and mice, the overall weight-of-evidence suggests a lack of in vivo mutagenicity. The present study was conducted to explore a potential mode of action further for tumor formation in rat mammary tissue. Fischer 344 rats were exposed to target concentrations of 0 or 200 ppm of DCE vapors (6 hours/day, 7 days/week) for at least 28 days; 200 ppm represents a concentration of ~20% higher than that reported to induce mammary tumors. Endpoints examined included DNA damage (via Comet assay), glutathione (reduced, oxidized and conjugated), tissue DNA adducts, cell proliferation and serum prolactin levels. Exposure to DCE did not alter serum prolactin levels with consistent estrous stage, did not cause cell proliferation in mammary epithelial cells, nor result in histopathological alterations in the mammary gland. DNA adducts were identified, including the N7 -guanylethyl glutathione adduct, with higher adduct levels measured in liver (nontumorigenic target) compared with mammary tissue isolated from the same rats; no known mutagenic adducts were identified. DCE did not increase the Comet assay response in mammary epithelial cells, whereas DNA damage in the positive control (N-nitroso-N-methylurea) was significantly increased. Although the result of this study did not identify a specific mode of action for DCE-induced mammary tumors in rats, the lack of any exposure-related genotoxic responses further contributes to the weight-of-evidence suggesting that DCE is a nongenotoxic carcinogen.

PBPK model reporting template for chemical risk assessment applications.

Physiologically-based pharmacokinetic (PBPK) modeling analysis does not stand on its own for regulatory purposes but is a robust tool to support drug/chemical safety assessment. While the development of PBPK models have grown steadily since their emergence, only a handful of models have been accepted to support regulatory purposes due to obstacles such as the lack of a standardized template for reporting PBPK analysis. Here, we expand the existing guidances designed for pharmaceutical applications by recommending additional elements that are relevant to environmental chemicals. This harmonized reporting template can be adopted and customized by public health agencies receiving PBPK model submission, and it can also serve as general guidance for submitting PBPK-related studies for publication in journals or other modeling sharing purposes. The current effort represents one of several ongoing collaborations among the PBPK modeling and risk assessment communities to promote, when appropriate, incorporating PBPK modeling to characterize the influence of pharmacokinetics on safety decisions made by regulatory agencies.

Effects of abandonment management on soil C and N pools in Moso bamboo forests.

Moso bamboo (Phyllostachys Pubescens) forests exhibit a great potential to sequestrate carbon dioxide from atmosphere and to mitigate global climate change. However, they were increasingly under abandoned (i.e., no fertilization, the low intensity and frequency of felling and bamboo shoot digging) due to decreasing economic values of bamboo-related products and increasing labor cost. So far, the changes in soil carbon (C) and nitrogen (N) pools in bamboo forests following abandonment are poorly addressed. In this study, Moso bamboo stands under intensively management and abandonment for different durations were sampled to explore the C and N pool dynamics at the top 40 cm soil. We classified abandonment durations into three categories: discarded or abandoned management for 1-6 years (DM-I), 7-12 years (DM-II) and 13-18 years (DM-III). Our results indicated that (1) soil organic carbon (SOC) storage was significantly increased with abandonment management compared with intensive management (Control, CK), but the durations of abandonment management had no significant effects on SOC. Microbial biomass carbon (MBC) concentration increased from DM-I to DM-III in the 0-40 cm soil layer (P < 0.01), and water-soluble organic carbon (WSOC) concentration decreased through DM-I (P < 0.01). (2) Abandonment management did not significantly affect soil total nitrogen (TN) storage at depth of 0-40 cm, with 9.54 Mg ha-1 for CK, 9.59 Mg ha-1 for DM-I, 9.89 Mg ha-1 for DM-II and 9.69 Mg ha-1 for DM-III. Water-soluble organic nitrogen (WSON) concentration significantly decreased from CK to DM-III. Ammonium nitrogen (NH4+-N) concentration increased from DM-I to DM-III (P < 0.01), and nitrate nitrogen (NO3--N) concentration decreased from CK to DM-III (P < 0.01). The results of the effects of abandonment durations on soil properties in Moso bamboo forests provide valuable information for forest restoration and management.

Mesoporous reduction state cobalt species-doped silica nanospheres: An efficient Fenton-like catalyst for dual-pathway degradation of organic pollutants.

A novel heterogeneous Co-containing Fenton-like catalyst consisting of mesoporous reduction state cobalt (RSCo)-doped silica (SiO2) nanospheres (mp-RSCo-SiO2 NSs) was prepared by an enhanced hydrothermal process. The catalyst exhibited very high activity and stability for a series of refractory pollutant degradation in a very wide pH range of 3.1-10.9. The Fenton-like reaction rate constant of this Co-containing catalyst was approximately 290 times higher than that of Co3O4 for pollutant degradation under the neutral and mild conditions. Based on the characterization, the catalyst possessed a porous nanosphere morphology, and the reduction state cobalt species, including nano-zero-valent cobalt (nZVCo) and Co2+, were found to be generated in the SiO2 framework through forming CoOSi bonds. During the Fenton-like reaction, the electron donation effect of organic pollutants was successfully realized through the interaction of "Pollutants â†’ Co2+/0-SiO2". The obtained electrons from pollutants were transferred to the catalyst surface and captured by H2O2, resulting in the generation of hydroxyl radicals (OH). Therefore, a dual-pathway degradation of the pollutants was realized: (I) oxidation and degradation as the electron donors for the system and (II) attacking and destruction by OH radicals. This work provided a new perspective on the effective utilization of the electrons of pollutants and the improvement of Fenton reaction efficiency.

Analytical methods impact estimates of trichloroethylene's glutathione conjugation and risk assessment.

The glutathione (GSH) conjugates, S-(1,2-dichlorovinyl)-glutathione (DCVG) and S-(1,2-dichlorovinyl)-L-cysteine (DCVC), have been implicated in kidney toxicity and kidney cancer from trichloroethylene (TCE) exposure. Considerable differences in blood and tissue levels of DCVG and DCVC have been reported, depending on whether HPLC/UV (High Performance Liquid Chromatography-Ultraviolet) or HPLC/MS (HPLC-Mass Spectrometry) was used. A side-by-side comparison of analytical results with HPLC/UV and HPLC/MS/MS (High Performance Liquid Chromatography-Tandem Mass Spectrometry) detection was undertaken to quantitatively compare estimates for DCVG and DCVG using rat and human tissues. For the HPLC method, DCVG and DCVC were initially derivatized with fluorodinitrobenzene (DNP). The results from the HPLC/UV method showed that derivatized-DCVC eluted at the solvent front and could not be quantified. Derivatized-DCVG, however, was quantified but significant interference was observed in all four control tissues (rat blood, liver, kidney; and human blood), resulting in average spike recoveries of 222-22,990%. In contrast, direct analysis of spiked tissues by HPLC/MS/MS resulted in recoveries of 82-127% and 89-117% for DCVG and DCVC, respectively. These differences in analytical results were further confirmed in tissues from TCE-treated rats, e.g., DCVG levels in rat liver were 18,000 times higher by HPLC/UV as compared to HPLC/MS/MS. Fraction collection of the derivatized-DCVG peak (obtained with the HPLC-UV method), followed by peak identification via an HPLC/UV/Q-TOF/MS/MS method, identified DNP-derivatized endogenous glutamate as the primary interfering substance that contributed to and exaggerated recoveries of DCVG. Thus, estimates of DCVG based on the HPLC/UV methods are not reliable; they will over-estimate the formation of the GSH conjugates of TCE and will artifactually exaggerate the potential cancer risk in humans from TCE exposure. Therefore, it is recommended that any characterization of cancer risks from TCE exposure attributable to the GSH conjugates of TCE rely on results obtained with the more specific and reliable HPLC/MS/MS method.

A highly sensitive and selective high pressure liquid chromatography with tandem mass spectrometry (HPLC/MS-MS) method for the direct peptide reactivity assay (DPRA).

While the HPLC/UV (high performance liquid chromatography coupled with ultra-violet spectrometry)-based DPRA (Direct Peptide Reactivity Assay) identifies dermal sensitizers with approximately 80% accuracy, the low selectivity and sensitivity of the HPLC/UV-based DPRA poses challenges to accurately identify the sensitization potential of certain chemicals. In this study, a high performance liquid chromatography coupled with tandem mass spectrometry (HPLC/MS-MS)-based DPRA was developed and validated according to the test guideline (OECD TG 442C). The final results were compared with the results from the traditional HPLC/UV-based guideline DPRA. This HPLC/MS-MS-based DPRA demonstrated similar performance compared to HPLC/UV-based DPRA using known dermal sensitizers and non-sensitizers according to the test guideline (OECD TG 442C). Following the validation, a challenge set of chemicals with either overlapping retention time with peptides, or higher hydrophobicity or chemicals potentially forming non-covalent interactions with peptides were assessed for dermal sensitization potential using both methods and the results were compared to existing in vivo data. The HPLC/MS-MS-based DPRA correctly predicted these chemicals as sensitizers or non-sensitizers; however, the HPLC/UV-based DPRA resulted in false-positive predictions for hydrophobic substances, chemicals with UV peaks overlapping with those of the peptide(s), and compounds that non-covalently interact with the peptides. These findings demonstrate the broader applicability and better sensitivity and selectivity of the LC/MS-MS-based DPRA over the traditional HPLC/UV-based guideline DPRA.