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The synthetic dye discharge is responsible for nearly one-fifth of the total water pollution from textile industry, which poses both environmental and public health risks. Herein, a solid substrate inoculated with fungi is proposed as an effective and environmentally friendly approach for catalyzing organic dye degradation. Pleurotus ostreatus was inoculated onto commercially available solid substrates such as sorghum, bran, and husk. Among these, P. ostreatus grown on sorghum (PO-SORG) produced the highest enzyme activity and was further tested for its dye biodegradation ability. Four dye compounds, Reactive Blue 19 (RB-19), Indigo Carmine, Acid Orange 7, and Acid Red 1 were degraded by PO-SORG with removal efficiencies of 93%, 95%, 95%, and 78%, respectively. Under more industrially relevant conditions, PO-SORG successfully degraded dyes in synthetic wastewater and in samples collected from a local textile factory, which reveals its potential for practical usage. Various biotransformation intermediates and end-products were identified for each dye. PO-SORG exhibited high stability even under relatively extreme temperatures and pH conditions. Over 85% removal of RB-19 was achieved after three consecutive batch cycles, demonstrating reusability of this approach. Altogether, PO-SORG demonstrated outstanding reusability and sustainability and offers considerable potential for treating wastewater streams containing synthetic organic dyes.

This investigation attempts to establish and verify a novel method for quantifying surface porosity of porous polymeric membranes via contact angle measurements. Herein, we fabricate a series of porous membranes via nonsolvent induced phase separation (NIPS) comprising different concentrations of polyvinylidene fluoride (PVDF) and PVDF-poly (methyl methacrylate) block co-polymer (PVDF-PMMA) with different concentrations of water and isopropyl alcohol (IPA) in the coagulation bath. Both sessile drop and captive bubble contact angle measurements are used to determine contact angles (and porosity) for both dry and wet membranes, respectively. The former method is probably applicable for membrane distillation, aeration and de-aeration where liquid water does not saturate the membrane, whereas the latter may be more indicative of pressure-driven aqueous membrane separations where the membrane is saturated through its cross-section. Image analysis of scanning electron microscope (SEM) images quantified dry membrane surface porosity. We propose a simple analytical model to obtain wet and dry membrane surface porosity from contact angle measurements. Our results suggest that the surface porosity calculated from both wet and dry contact angle data correlates strongly with the surface porosity calculated from SEM values. However, wet contact angles of the membranes with high porosities produce significantly higher porosity values, which also establishes the importance of porous membrane swelling in determining membrane porosity for aqueous membrane separations.

Groundwater remediation technologies that can destroy per- and polyfluoroalkyl substances (PFAS) in situ are in high demand. To address this need, using flow-through electrochemical reactors we compared the performance of three mesh electrode materials that may be implemented in the subsurface as permeable reactive barriers. A Magnéli-phase titanium suboxides TinO2n-1 anode achieved higher perfluorooctane sulfonate (PFOS) oxidation rates and lower energy consumption than boron-doped ultrananocrystalline diamond and IrO2-Ta2O5 mixed metal oxides, and was thus selected for more detailed testing regarding the impacts of varying current density, flow velocity, electrolyte conductivity, and PFOS concentration. Over 99% of PFOS removal was achieved under continuous flow conditions. The fluorine mass balance showed that most PFOS-bonded F was released as fluoride, while no organic intermediates were detected in the aqueous phase. Each ∼2% of fluorine was recovered as HF and organofluorine intermediates in the gas phase. A comparison of 10 PFAS revealed a hydrophobicity-driven increase in oxidation rate with increasing perfluoroalkyl chain length as well as faster oxidation kinetics for perfluoroalkyl carboxylic acids compared to perfluoroalkane sulfonic acids, likely due to contributions from electrochemically activated sulfate. The energy consumption of PFAS treatment under simulated slow-flow groundwater conditions was substantially higher than in ex situ electrochemical systems optimized for enhanced mass transfer. Consequently, future work should focus on in situ treatment design optimization with an emphasis on power requirements. Collectively, our investigations demonstrate that among the few water treatment technologies capable of breaking the carbon-fluorine bond, electrochemical treatment is a promising approach for in situ destruction of PFAS in the subsurface.

Subsurface soil naturally experiences dry-wet and freeze-thaw cycles, which could affect the leaching of previously adsorbed pollutants. A slow release of poly- and perfluoroalkyl substances (PFAS) from impacted subsurface soil may serve as a long-term diffuse source of PFAS to groundwater. Yet, the extent to which these weathering conditions may affect the subsurface release of PFAS is unknown. We subjected columns packed with soil pre-adsorbed with perfluorooctanoic acid (PFOA) to dry-wet and freeze-thaw cycles and observed a spike in PFOA concentration in leachate following each weathering treatment compared to no weathering treatment. Weathering conditions released a high concentration of soil colloids, which were confirmed by particle-size distribution analysis, SEM-EDS, and XRD. Fractionation of PFOA in the water sample reveals that up to 36 % of leached PFOA was associated with soil colloids. Thus, previous studies that did not account for colloids might have underestimated the leaching of PFAS from the soil. Overall, the results indicate that natural weathering conditions can enhance subsurface leaching of colloids and colloid-associated PFOA. Therefore, current conceptual site models to quantify the leaching of PFAS from source zones should account for weathering and the contribution of colloids.

Biofilms are a leading cause of infections, especially those initiated on medical tubing. Quantification of pathogenic biofilms is critical for systematic determination of infections, antibiotics prescription, and implant replacement. By the time infectious pathogens are detected in fluids such as blood or urine, substantial and potentially life-threatening biofilms are likely to have already formed. These biofilms can have broad ranging patient care and cost implications. Here we propose a non-strain-specific protocol combining four microbiological assays, which are rarely used together in clinical biofilm assessment, to accurately quantify cellular and extracellular components attached to medical surfaces. Our results demonstrate that the shortcomings of standard approaches can be overcome through the conjunct analysis of total protein (modified Lowry), total biomass (quantitative polymerase chain reaction), cellular activity (ATP luminescence), and extracellular polymeric substances (Periodic Acid-Schiff assay). The efficacy of this multipronged approach was verified using four pathogenic, clinical isolates (Pseudomonas aeruginosa, Staphylococcus aureus, methicillin resistant-Staphylococcus aureus, and Candida albicans) and two types of silicone catheters in vitro. Despite the variation of biofilm matrices among infectious agents, this approach comprehensively quantified the pathogenic load as well as fouling resistance in indwelling catheters obtained from patients. The sensitivity, reproducibility, multi-species specificity, and high-throughput potential makes this approach valuable for quality assessment of catheters, implants, and ventilators in hospital settings.

Vinyl chloride (VC) and 1,4-dioxane (DX) are carcinogens and co-occurring groundwater pollutants. Co-contaminants often affect the ability of microorganisms to biodegrade individual constituents. One of the mechanisms by which microbial cells overcome toxic inhibition is by transforming the inhibitory compounds. In this study, while VC inhibited DX biodegradation, it was surprisingly utilized as a growth substrate by Pseudonocardia dioxanivorans CB1190. Increasing concentrations of VC decreased DX biodegradation rates, whereas increasing DX did not have a strong effect on VC biodegradation. CB1190 was able to biodegrade both compounds simultaneously. The dxmB and aldH gene targets were down regulated during VC biodegradation and were likely not induced by VC. After incubating CB1190 with 13C-labeled VC, the detection of isotopic labeled metabolites engaged in lipid and protein synthesis (e.g., aspartate, alpha-ketoglutarate, acetyl-CoA) and energy production (e.g., ATP) provided direct evidence of CB1190’s ability to use VC as a source of carbon and energy. Collectively, these results confirm that CB1190 utilizes VC, a strong DX degradation inhibitor, as a growth substrate. This ability to aerobically degrade VC as well as DX would make CB1190 an attractive bioaugmentation culture at sites where enhanced reductive dechlorination stalls at VC due to oxygen intrusion or strain-specific limitations.