ACS Environmental Au最新文献

Wastewater is a significant source of copper to freshwater environments, which can severely harm aquatic life. The bioavailability and toxicity of copper in water are influenced by its complexation with dissolved organic matter (DOM). Speciation models, like the biotic ligand model (BLM) that guides Cu regulations, assume DOM is dominated by humic substances. Research suggests that anthropogenic compounds in wastewater discharge may be important copper binding ligands, although their identities remain largely unknown. To address this knowledge gap, we identified and quantified organic copper species isolated from 24 h composite wastewater samples by solid phase extraction (SPE) using liquid chromatography (LC) with inductively coupled plasma mass spectrometry (ICPMS) and electrospray ionization mass spectrometry (ESIMS). Analyses of samples across different stages of treatment revealed the net removal of Cu (73%) and DOC (66%). LC-ICPMS showed that certain complexes were selectively removed, while others evaded removal or were generated during treatment. Relatively hydrophobic complexes decreased in abundance from the initial to the secondary treatment stage. In contrast, more hydrophilic organic Cu complexes, likely formed during treatment, showed a significant increase from the secondary to the tertiary stage. The molecular mass and formula of seven discrete chromatographically resolved complexes were identified by LC-Orbitrap MS. Six were detected only in wastewater, and one was detected in all the wastewater and river samples. Identification of these compounds provides additional evidence for the formation of new copper-binding ligands during treatment and confirms the presence of nitrogen- and sulfur-containing compounds with copper-chelating properties in the wastewater. These findings demonstrate the utility of LCMS approaches for identifying and quantifying distinct organic-copper species in wastewater, as well as tracking their changes and removal during the treatment process.

Wastewater is a significant source of copper to freshwater environments, which can severely harm aquatic life. The bioavailability and toxicity of copper in water are influenced by its complexation with dissolved organic matter (DOM). Speciation models, like the biotic ligand model (BLM) that guides Cu regulations, assume DOM is dominated by humic substances. Research suggests that anthropogenic compounds in wastewater discharge may be important copper binding ligands, although their identities remain largely unknown. To address this knowledge gap, we identified and quantified organic copper species isolated from 24 h composite wastewater samples by solid phase extraction (SPE) using liquid chromatography (LC) with inductively coupled plasma mass spectrometry (ICPMS) and electrospray ionization mass spectrometry (ESIMS). Analyses of samples across different stages of treatment revealed the net removal of Cu (73%) and DOC (66%). LC-ICPMS showed that certain complexes were selectively removed, while others evaded removal or were generated during treatment. Relatively hydrophobic complexes decreased in abundance from the initial to the secondary treatment stage. In contrast, more hydrophilic organic Cu complexes, likely formed during treatment, showed a significant increase from the secondary to the tertiary stage. The molecular mass and formula of seven discrete chromatographically resolved complexes were identified by LC-Orbitrap MS. Six were detected only in wastewater, and one was detected in all the wastewater and river samples. Identification of these compounds provides additional evidence for the formation of new copper-binding ligands during treatment and confirms the presence of nitrogen- and sulfur-containing compounds with copper-chelating properties in the wastewater. These findings demonstrate the utility of LCMS approaches for identifying and quantifying distinct organic-copper species in wastewater, as well as tracking their changes and removal during the treatment process.

The back diffusion of trichloroethylene (TCE) between low permeability zones (LPZ) and transmissive zones in the subsurface presents remediation challenges. This study investigates in situ chemical oxidation (ISCO) using a sodium persulfate sustained release rod (SPS SR-rod) for potential TCE remediation in the LPZ within a two-dimensional sand tank. The tank simulates a dual permeability porous medium with hydraulic gradients of 0.01 and 0.05. The SPS SR-rod placed within the LPZ released an average PS concentration of ∼625 mg/L laterally, with initial peak concentrations of 7000–10,000 mg/L. When the rod was placed atop the LPZ, lower PS concentrations were observed compared to placement within the LPZ. A separate evaluation of both SPS SR-rod placements in a 2D sand tank injected with pure TCE tested the oxidant’s ability to address soil-sorbed TCE. The rod atop the LPZ can mitigate dual permeability layers and creates a depletion zone at the high permeability zone to reduce contaminant transport from the LPZ. The rod within the LPZ reduces TCE lateral dispersion. The persistence and slow release of SPS in the LPZ suggest that the SPS SR-rod could effectively extend the time period of ISCO remediation of low-concentration TCE in the LPZ and the surrounding environment.

The back diffusion of trichloroethylene (TCE) between low permeability zones (LPZ) and transmissive zones in the subsurface presents remediation challenges. This study investigates in situ chemical oxidation (ISCO) using a sodium persulfate sustained release rod (SPS SR-rod) for potential TCE remediation in the LPZ within a two-dimensional sand tank. The tank simulates a dual permeability porous medium with hydraulic gradients of 0.01 and 0.05. The SPS SR-rod placed within the LPZ released an average PS concentration of ∼625 mg/L laterally, with initial peak concentrations of 7000-10,000 mg/L. When the rod was placed atop the LPZ, lower PS concentrations were observed compared to placement within the LPZ. A separate evaluation of both SPS SR-rod placements in a 2D sand tank injected with pure TCE tested the oxidant's ability to address soil-sorbed TCE. The rod atop the LPZ can mitigate dual permeability layers and creates a depletion zone at the high permeability zone to reduce contaminant transport from the LPZ. The rod within the LPZ reduces TCE lateral dispersion. The persistence and slow release of SPS in the LPZ suggest that the SPS SR-rod could effectively extend the time period of ISCO remediation of low-concentration TCE in the LPZ and the surrounding environment.

Technologies using liquid-transfer membranes, such as microfiltration, ultrafiltration, and reverse osmosis, have been widely applied in water and wastewater treatment. In the last few decades, gas-transfer membranes have been introduced in various fields to facilitate mass transfer, in which gaseous compounds permeate through membrane pores driven by gradients in chemical concentration or potential. A notable knowledge gap exists among researchers working on these emerging gas-transfer membranes as they approach this subject from different angles and areas of expertise (e.g., material science versus microbiology). This review explores the versatile applications of gas-transfer membranes in water and wastewater treatment, categorizing them into three primary types according to the function of membranes: water vapor transferring, gaseous reactant supplying, and gaseous compound extraction. For each type, the principles, evolution, and potential for further development were elaborated. Moreover, this review highlights the potential knowledge transfer between different fields, as insights from one type of gas-transfer membrane could potentially benefit another. Despite their technical innovations, these processes still face challenges in practical operation, such as membrane fouling and wetting. We advocate for research focusing on more practical and sustainable membranes and careful consideration of these emerging membrane technologies in specific scenarios. The current practicality and maturity of these emerging processes in water and wastewater treatment are described by the Technology Readiness Level (TRL) framework. Particularly, ongoing fundamental progress in membranes and engineering is expected to continue fueling the future development of these technologies.

Technologies using liquid-transfer membranes, such as microfiltration, ultrafiltration, and reverse osmosis, have been widely applied in water and wastewater treatment. In the last few decades, gas-transfer membranes have been introduced in various fields to facilitate mass transfer, in which gaseous compounds permeate through membrane pores driven by gradients in chemical concentration or potential. A notable knowledge gap exists among researchers working on these emerging gas-transfer membranes as they approach this subject from different angles and areas of expertise (e.g., material science versus microbiology). This review explores the versatile applications of gas-transfer membranes in water and wastewater treatment, categorizing them into three primary types according to the function of membranes: water vapor transferring, gaseous reactant supplying, and gaseous compound extraction. For each type, the principles, evolution, and potential for further development were elaborated. Moreover, this review highlights the potential knowledge transfer between different fields, as insights from one type of gas-transfer membrane could potentially benefit another. Despite their technical innovations, these processes still face challenges in practical operation, such as membrane fouling and wetting. We advocate for research focusing on more practical and sustainable membranes and careful consideration of these emerging membrane technologies in specific scenarios. The current practicality and maturity of these emerging processes in water and wastewater treatment are described by the Technology Readiness Level (TRL) framework. Particularly, ongoing fundamental progress in membranes and engineering is expected to continue fueling the future development of these technologies.