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Traditional composting is a well-suited biotechnology for on-farm management of livestock manure (LM) but still leads to the release of toxic micropollutants and imbalance of nutrients. One

Per- and polyfluoroalkyl acids (PFAAs) including polyfluoroalkyl carboxylic acids and polyfluoroalkyl sulfonic acids are a large category of crucial environmental pollutants of global concern. Besides known PFAAs, numerous unknown species may exist in the environment, urgently needing discovery and characterization. This study implemented nontarget analysis for a group of novel PFAA pollutants, viz., iodinated PFAAs (I-PFAAs) in wastewater from a fluorochemical manufacturing park by liquid chromatography-high-resolution mass spectrometry in combination with an iodine-specific data-processing algorithm. The algorithm took into account the diagnostic fragment iodine ion (I

The environmental occurrence of PFAS in different water systems and their likely sources and fate is discussed.

Per- and polyfluoroalkyl acids (PFAAs) including polyfluoroalkyl carboxylic acids and polyfluoroalkyl sulfonic acids are a large category of crucial environmental pollutants of global concern. Besides known PFAAs, numerous unknown species may exist in the environment, urgently needing discovery and characterization. This study implemented nontarget analysis for a group of novel PFAA pollutants, viz. iodinated PFAAs (I-PFAAs) in wastewater by liquid chromatography-high-resolution mass spectrometry in combination with an iodine-specific data-processing algorithm. The algorithm took into account of the diagnostic fragment iodine ion (I–) together with carbon and sulfur isotopologue distributions. In total, 21 I-PFAA formulas involving 24 congeners were identified. Semiquantification was conducted, and the total concentrations of I-PFAAs were 1.9-311.9 ng/mL, indicating non-negligible pollution of I-PFAAs in the wastewater. The determined concentrations along with predicted environmental behaviors and toxicities demonstrate that I-PFAAs merit further in-depth investigation. The analytical method including the instrumental analysis and data-processing algorithm can be extended to screening and identification of I-PFAAs in other matrices. Furthermore, the analysis results for the first time provide cognition on the occurrence features and pollution status of I-PFAAs in the environment.

This is the first comprehensive overview of laccase-triggered anabolism from fundamental theory to biotechnology applications. Laccase is a typical biological oxidordeuctase that induces the one-electronic transfer of diverse substrates for engendering four phenoxy radicals with concomitant reduction of O

Formation of chlorate (ClO3−) and perchlorate (ClO4−) as by-products in electrooxidation process has raised concern. In the present study, the formation of ClO3− and ClO4− in the presence of 1.0 mM Cl− on boron doped diamond (BDD) and Magneli phase titanium suboxide (Ti4O7) anodes were evaluated. The Cl− was transformed to ClO3− (temporal maximum 276.2 µM) in the first 0.5 h on BDD anodes with a constant current density of 10 mA cm2, while approximately 1000 µM ClO4− was formed after 4.0 h. The formation of ClO3− on the Ti4O7 anode was slower, reaching a temporary maximum of approximately 350.6 µM in 4.0 h, and the formation of ClO4− was also slower on the Ti4O7 anode, taking 8.0 h to reach 780.0 µM. Compared with the BDD anode, the rate of ClO3− and ClO4− formation on the Ti4O7 anode were always slower, regardless of the supporting electrolytes used in the experiments, including Na2SO4, NaNO3, Na2B4O7, and Na2HPO4. It is interesting that the formation of ClO4− during electrooxidation was largely mitigated or even eliminated, when methanol, KI, and H2O2 were included in the reaction solutions. The mechanism of the inhibition on Cl− transformation by electrooxidation was explored.

Electrooxidation (EO) has been shown effective in degrading per- and polyfluoroalkyl substances (PFASs) in water, but concurrent formation of chlorate and perchlorate in the presence of chloride is of concern due to their toxicity. This study examined EO treatment of three representative PFASs, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and 6:2 fluorotelomer sulfonate (6:2 FTS), in chloride-containing solutions on pristine and surface-fluorinated Ti

Defect engineering in an electrocatalyst, such as doping, has the potential to significantly enhance its catalytic activity and stability. Herein, we report the use of a defect engineering strategy to enhance the electrochemical reactivity of Ti4O7 through Ce3+ doping (1-3 at. %), resulting in the significantly accelerated interfacial charge transfer and yielding a 37-129% increase in the anodic production of the hydroxyl radical (OH•). The Ce3+-doped Ti4O7 electrodes, [(Ti1-xCex)4O7], also exhibited a more stable electrocatalytic activity than the pristine Ti4O7 electrode so as to facilitate the long-term operation. Furthermore, (Ti1-xCex)4O7 electrodes were also shown to effectively mineralize perfluorooctanesulfonate (PFOS) in electrooxidation processes in both a trace-concentration river water sample and a simulated preconcentration waste stream sample. A 3 at. % dopant amount of Ce3+ resulted in a PFOS oxidation rate 2.4× greater than that of the pristine Ti4O7 electrode. X-ray photoelectron spectroscopy results suggest that Ce3+ doping created surficial oxygen vacancies that may be responsible for the enhanced electrochemical reactivity and stability of the (Ti1-xCex)4O7 electrodes. Results of this study provide insights into the defect engineering strategy for boosting the electrochemical performance of the Ti4O7 electrode with a robust reactivity and stability.

Treatment of large volumes of waters contaminated by per- and polyfluoroalkyl substances (PFAS) remains a challenge. This work presented a systematic study on PFAS removal by foam fractionation (FF). Experiments were conducted on both laboratory-spiked and environmental water samples containing PFASs. It is found that higher air flow, greater ionic strength, and addition of thickener boosted PFAS removal in the defoamed bottom solutions and intensified enrichment in the collected foam. FF treatments of a landfill leachate, a groundwater contaminated by aqueous film-forming foams, and a wastewater treatment plant effluent sample were evaluated. The removal reached above 70% for most monitored PFASs, except the ones of short alkyl chains. PFAS concentrations in the final collected foams were up to over 30 × than that in the original samples. Analysis using high-resolution mass spectrometry revealed enrichment of non-target PFASs by FF. The results of this study demonstrate great effectiveness of FF in removing most PFASs from waters, producing low-volume, highly concentrated solutions of PFASs in all tested environmental samples.

The effect of electrochemical degradation on Magnéli phase Ti

Our recent findings indicate effective electrochemical degradation of perfluoroalkyl acids (PFAAs) in aqueous solutions using novel titanium suboxide (TSO) anodes. This provides a potentially promising technology to treat per- and polyfluoroalkyl substances (PFASs) in legacy AFFF stockpiles or in wastewater and contaminated groundwater. The degradation of PFAAs in TSO-based electrooxidation was evaluated with solutions of different compositions containing eight PFAAs either individually or in a mixture and under a range of operation conditions. Surface area normalized pseudo-first order rate constants were obtained and interpreted in terms of PFAA degradation behaviors and mechanisms. The PFAA degradation rates were further correlated to the molecular and electronic descriptors of the chemicals calculated based on density functional theory. The results of this study further the understanding of PFAS degradation in TSO-based anodic oxidation and provide a basis for process optimization, design and scaling.

Managing per- and polyfluoroalkyl substance (PFAS) contamination has gained worldwide attention due to their ubiquitous occurrence in water systems. Anion exchange resins (AERs) have been proven effective in removing both long-chain and short-chain PFASs. In this study, an explicit model was developed to describe the breakthrough behavior of an individual PFAS as a single solute onto anion exchange resin in a column filtration process. The model was further modified to predict the breakthrough curve of co-existing PFASs on AER in multi-solute systems by incorporating a separation factor describing the competitive adsorption and a blockage factor describing the loss of adsorption sites. Rapid small-scale column tests (RSSCTs) were performed with six AERs of various properties and three model PFASs in both single- and multi-solutes systems. The breakthrough behaviors of RSSCTs for both single- and multi-solute systems were found adequately described by the models developed in this study. The experiments and accompanied model simulations reveal some important relationships between the AER performance and the properties of both the AERs and the PFASs.

Organic layer formation in the form of thatch is a major problem in managed turfgrass systems. Biweekly application of laccase enzyme has been well-documented to facilitate the degradation of thatch and reduce the accumulation rate of organic matter in ‘Crenshaw’ creeping bentgrass (Agrostis stolonifera L.). A field experiment involving creeping bentgrass was conducted to evaluate the residual effects on thatch accumulation after ceasing laccase applications. A significant reduction in thatch layer thickness was observed at 6, 12, and 18 months after treatment initiation when laccase was applied at different rates and frequencies. Residual effects of laccase application were observed for thatch layer thickness, but no additional accumulation of thatch was observed 6 months after treatment cessation. At 18 months after treatment initiation, a significant increase in the thatch layer was observed where treatments had been ceased for 12 months, but no thatch accumulation was observed for laccase treatment for a second 6-month period during the second year. This information is critical to turf practitioners when developing laccase application protocols. Limiting laccase applications for a period of 6 months during 1 year was shown to be effective for thatch control.

In this study, we used a simple and rapid colourimetric reaction for visual sensing of Fe2+ and Pb2+ ions in water by employing nano-MnO2 as a natural oxidase mimic to respectively catalyse ABTS an...

Industrial microbial waste (IMW) from amylase production using Aspergillus niger was characterized and utilized as novel adsorbent to remove two model cationic dyes (crystal violet, CV; methylene blue, MB) in their single and binary system. IMW was composed of organic Aspergillus niger biomass and inorganic perlite and diatomite, and thereby was regarded as a composite sorbent which was also characterized using FTIR, SEM, and XPS. The sorptive properties of IMW were studied in batch experiments by varying initial dye concentration, contact time, temperature, sorbent dosage, and NaCl concentration. The adsorption of CV and MB exhibited very similar trends in both single and binary dye solutions. Isotherms, kinetics, and thermodynamics were used to describe the sorption processes. The Langmuir model provided a good fit of the experimental data with the maximum monolayer adsorption (qm) of 175.4 mg/g and 92.6 mg/g for CVs and MBs, respectively in the single dye system. In the mixed dye solutions, the qm for CVm and MBm was reduced to 74.6 mg/g and 52.9 mg/g, respectively. Second-order kinetic model (R2 > 0.999) better explained the adsorption for the two dyes in single or mixed forms, suggesting chemical sorption nature of the process. The adsorption was dominated primarily by membrane diffusion and found to be endothermic and spontaneous. The IMW can thus be repurposed as a novel and promising cleaning agent for removal of organic pollutants from miscellaneous wastewaters.

Agro-processing waste oiltea shell (OTS) has been previously proven effective in removing dye from water by adsorption. This study further evaluated its capability to adsorb heavy metals in aqueous solution. Adsorbent dosage, pH, ion concentration, temperature, and contact time were investigated in batch experiments. Pseudo-second order kinetic better described the adsorption process for the three ions. Langmuir equation was more suitable for Cu2+ and Cd2+, while Freundlich for Pb2+. The maximum adsorption capacity was 22.4 (Pb2+), 12.1 (Cu2+), and 14.2 mg/g (Cd2+), respectively. The adsorption was spontaneous and endothermic. Adsorption was then performed in column and Thomas model was fitted, based on which the maximum adsorption capacity was 7.42 (Cu2+), 4.17 (Pb2+), and 18.02 mg/g (Cd2+), respectively. High removal rate of metal ions and dye methylene blue was also achieved from their mixture solution. OTS is therefore a promising biosorbent in treating wastewater with organic and inorganic pollutants.

Magneli phase Ti4O7 ceramic materials having extensive interconnecting macropores with an average pore size of 2.6 μm and 21.6% porosity were fabricated using a high-temperature sintering method, and then tested as an anode in a batch mode for electrooxidative mineralization of environmentally persistent poly- and perfluoroalkyl substances (PFASs) such as perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS). Tests were also conducted with other “non-active” electrodes for comparison, including Ce-doped PbO2 and Ti/BDD electrodes. The results showed that the porous Ti4O7 ceramic anode exhibited greater PFOA/PFOS oxidation rates than those of the other electrodes. Only trace amounts of perfluorocarboxylic acid (PFCAs) with shortened chain lengths were observed as intermediates during PFOA mineralization. SO42− and F− were recovered as the mineralization products of PFOS electrooxidation, while no organofluorine compounds such as shorter-chain PFCAs were detected in the solution by high-resolution mass spectrometry (HRMS). Possible mechanisms for PFOA/PFOS mineralization over porous Ti4O7 ceramic electrode were proposed on the basis of reaction products analysis. In addition, the developed porous Ti4O7 ceramic anode was successfully applied to treatment of the still bottom liquid waste containing high concentrations of poly- and perfluoroalkyl substances (PFASs) as well as high chloride and organic content concentrations from the regeneration of ion-exchange resin that had been used for remediation of PFASs-impacted groundwater. The results illustrate the promise of the macroporous Magneli phase Ti4O7 ceramic materials for electrochemical treatment of PFASs in water.

Concerns have been on the rise regarding the use of chlorine-based sanitizers for fresh produce sanitation due to the production of toxic disinfection by-products (DBPs). This study was undertaken to evaluate the efficacy of activated persulfate in inactivating Escherichia coli O157:H7 and Listeria monocytogenes in pure culture. The objectives were to study the effect of persulfate to activator ratios and determine the major contributing radical in pathogen inactivation. A five-strain cocktail of each pathogen was treated with sodium persulfate activated by ferrous sulfate or sodium hydroxide for 60 s or 120 s. Non-selective agars supplemented with sodium pyruvate were used for pathogen enumeration. The steady-state concentrations of free radicals were quantified using HPLC-DAD. Radical scavengers (tert-butanol, isopropanol, and benzoquinone) were used to determine the major contributing radical in pathogen inactivation. The results showed more than 7 log CFU/mL reductions can be achieved in 120 s for both pathogens at appropriate activation conditions. For ferrous activation, the persulfate to ferrous ratio played an important role in the overall inactivation efficacy. The maximum pathogen reduction (7.77 log CFU/mL for E. coli O157:H7 and 7.25 log CFU/mL for L. monocytogenes) was achieved at persulfate to ferrous molar ratio of 1:0.33 when the initial persulfate concentration was set at 40 mmol/L. Further increase or decrease of ferrous ratio always leads to lower pathogen reductions. For alkaline activation, the inactivation efficacy increased with more initial sodium hydroxide. The maximum reduction was achieved at 40 mmol/L persulfate with 30 mmol/L sodium hydroxide for E. coli O157:H7 (6.21 log CFU/mL reduction) and at 500 mmol/L persulfate with 350 mmol/L sodium hydroxide for L. monocytogenes (8.64 log CFU/mL reduction). Also, persulfate activated by sodium hydroxide always achieved significantly (P 0.05) higher microbial reductions than sodium hydroxide or persulfate alone. L. monocytogenes was generally more resistant against the activated persulfate treatment compared with E. coli O157:H7, which might be due to the different cell envelop structures between Gram-positive and Gram-negative bacteria. Hydroxyl radical was demonstrated to be the major radical to inactivate both pathogens in ferrous activation while superoxide radical was demonstrated to be the major radical to inactivate both pathogens in alkaline activation.

Benzophenone-4 (BP4) is UV-filter that is widely in sunscreens and cosmetics to prevent skin damage from sunlight exposure. Washing off of BP4 from the human body in swimming pools represents a direct source of BP4 in the environment. In this study, we investigated the transformation of BP4 by free chlorine, chloramine, and UV/chlorine, which can be found in swimming pool water. It was found that BP4 can be rapidly removed by both chlorine and chloramine treatment, but only chlorination led to appreciable formation of chlorinated disinfection by-products (DBPs), such as dichloroacetic acid and trichloroacetic acid. However, chloramination of BP4 resulted in higher levels of chlorinated intermediates, which were relatively recalcitrant to further chlorination. The UV/chlorine process was significantly more efficient than the chlorine treatment alone for BP4 removal and resulted in trace chlorinated intermediates and formation of DBPs. Radical scavenger tests revealed that the removal of BP4 in the UV/chlorine process was mostly ascribed to reactions with the Cl and OH generated from HClO photolysis. The presence of methanol as a radical scavenger resulted in incomplete removal of BP4 in the UV/chlorine process and enhanced the formation of DBPs. The increase in DBP formation was because the residual BP4 can be exited to a triplet state (3BP4∗) upon UV irradiation. 3BP4∗ subsequently reacted with O2 to form 1O2, a reactive oxygen species that generated DBPs by reacting with chlorinated intermediates in water. All benzophenone-type UV-filters may have similar photochemical activity and thus influence the transformation of other organics in sunlit surface water environments.

A reactive electrochemical membrane (REM) system was developed with titanium suboxide microfiltration membrane serving as the filter and the anode, and was examined to inactivate Escherichia coli (E. coli) in water at various current densities. After passing through the membrane filter, the concentration of E. coli decreased from 6.46 log CFU/mL to 0.18 log CFU/mL. The REM operation and effects, including membrane pressure, anode potential, protein leakage, and cell morphology, were characterized under different treatment conditions. It was found that several mechanisms, including membrane filtration, external electrical field influence, and direct oxidation, functioned in concert to lead to bacteria removal and inactivation, and direct oxidation likely played the major role. As revealed by scanning electron microscope and extracellular protein analysis, high current density and voltage caused severe cell damage that resulted in partial or complete cell disintegration. The removal of a model virus, bacteriophage MS2, was also investigated at the current density of 10 mA cm−2 and achieved 6.74 log reduction compared to the original concentration (1011 PFU/mL). In addition to illustration of mechanisms, this study may provide a potentially promising approach that is suitable for decentralized treatment to meet dispersed water disinfection needs.

Perfluorooctanoic acid (PFOA) can induce undesirable effects to humans and animals and has thus attracted much attention from the public and scientific communities in recent years. Extensive studies have been devoted to exploring PFOA degradation in aqueous phase, while information for that in soil is rather limited. Understanding the transformation of PFOA in soil is important in developing strategies to assess and manage its environmental fate. In this study, we have demonstrated that PFOA can be effectively degraded by enzyme catalyzed oxidative humification reactions (ECOHRs) with a natural organic material, soybean meal, as the mediator. In the presence of soybean meal and laccase, PFOA was degraded 24% in water after 36 days, 40% in soil slurry after 140 days. The water extract of soybean meal contained high concentrations of natural organic mediators and multivalent metal ions, both of which were essential to PFOA degradation by ECOHRs. The ECOHR degradation products of PFOA in soil were identified to be partially fluorinated organic compounds, and the molecular features of the products suggest that the degradation mechanism involves free radical chain reaction processes, which was initiated by direct free radical attacks on the C C bonds in perfluoroalkyl acids.

Defect engineering in an electrocatalyst, such as doping, has the potential to significantly enhance its catalytic activity and stability. Herein, we report the use of a defect engineering strategy to enhance the electrochemical reactivity of Ti

This study examined the feasibility of a novel treatment train that combines electrocoagulation (EC) with electrooxidation (EO) treatment to remove and degrade per- and polyfluoroalkyl substances (PFASs) from water. Electrocoagulation with a zinc anode could effectively remove PFASs from water, and long-chain PFASs (C7-C10) tended to have a higher removal rate. Foam was generated when a relatively high current density (>1 mA cm-2) was applied to a relatively high PFAS concentration (each PFAS > 0.1 μM) during EC, which promoted the separation of PFASs from the bulk solution, especially for long-chain PFASs. Isotherm-like adsorption results indicated that competitive adsorption on floc occurred between PFASs when no foam was produced in a solution containing 10 different PFASs. Acid dissolution methods could recover and concentrate 10 PFASs in controlled volumes from both the floc and the foam, and it was also successfully applied in groundwater collected from a contaminated site. The concentrated PFASs in the acid solutions were efficiently destructed using EO treatment with a Ti4O7 anode at 10 mA cm-2, and no supplement of electrolyte was needed for the floc dissolved solution. This electrochemical-based process can economically separate, concentrate and destroy PFASs in groundwater and wastewater.

This study examined the degradation of perfluorooctanesulfonate (PFOS) in electrochemical oxidation (EO) processes in the presence of trichloroethylene (TCE). The EO experiment was performed in a gas-tight reactor using Magneli phase titanium suboxide (Ti4O 7) as the anode. The experimental data demonstrated that 75% of PFOS (2 μM) was degraded at 10 mA/cm2 current density in 30 min without TCE present in the solution, while the presence of 76 μM TCE apparently inhibited the degradation of PFOS, reducing its removal down to 53%. Defluorination ratio suggested that PFOS was significantly mineralized upon EO treatment, and it appeared to be not influenced by the presence of TCE. The respective pseudo-first order rate constants (kobs) of PFOS removal were 0.0471 and 0.0254 min-1 in the absence and presence of TCE. The degradation rates of both PFOS and TCE increased with current density rising from 2.5 to 20 mA/cm2. In the presence of TCE, chloride, chlorate, and perchlorate were formed that accounted for 79.7 %, 5.53%, and 1.51% of the total chlorine at 60 min. This work illustrates the promise of the Magneli phase Ti4O7 electrode based electrochemical oxidation technology for degrading per- and polyfluoroalkyl substances (PFASs) and co-contaminants in groundwaters.

This pilot-scale field demonstration evaluated the remediation of poly- and perfluoroalkyl substances (PFAS) from groundwater contaminated with aqueous film-forming foam (AFFF) from a coupled regenerable ion exchange resin (IXR) and electrochemical oxidation (EO) treatment train. A pilot-scale IXR system was used that incorporates a novel resin regeneration process, and recovers and reuses the majority of the regenerant solution using distillation. The pilot system removed PFAS from ∼1,000,000 liters (L) (approximately 260,000 gallons) of contaminated groundwater from a fire training area, and treated effluent from the IXR system was non-detect for PFOA and PFOS. The concentrated waste stream (i.e., still bottom) from IXR was treated on-site by an EO system with Ti4O7 electrodes, achieving 80% - 98% destruction of PFOA and PFOS. The surface area normalized first-order rate constants (kSA) were 3.96×10−7 m s−1 and 7.92×10−7 m s−1 for PFOA and PFOS respectively, with short-chain perfluoroalkyl acids (PFAAs) identified as intermediate degradation products. Based on the fluoride recovered and PFAS mass loss measured at the end of EO treatment, fluoride release ratios were 130% for still bottom sample 1 (SB1) and 215% for still bottom sample 2 (SB2), indicating mineralization of unquantified fluorinated compounds in the waste stream. Overall, the electric energy consumed per order of magnitude reduction in concentration (EE/O) for treating PFOA and PFOS in groundwater by the IXR-EO treatment train was 0.131 – 0.161 kWh/m3 for PFOA and 0.071 – 0.094 kWh/m3 for PFOS, which was orders of magnitude lower than the reported EE/O values for stand-alone electrochemical treatment. The results of this field demonstration show the promise of coupling regenerable IXR with EO for cost-effective removal, concentrating, and destroying PFAS from groundwater.