A Review on the Fate of Legacy and Alternative Antimicrobials and Their Metabolites during Wastewater and Sludge Treatment

Antimicrobial compounds are used in a broad range of personal care, consumer and healthcare products and are frequently encountered in modern life. The use of these compounds is being reexamined as their safety, effectiveness and necessity are increasingly being questioned by regulators and consumers alike. Wastewater often contains significant amounts of these chemicals, much of which ends up being released into the environment as existing wastewater and sludge treatment processes are simply not designed to treat many of these contaminants. Furthermore, many biotic and abiotic processes during wastewater treatment can generate significant quantities of potentially toxic and persistent antimicrobial metabolites and byproducts, many of which may be even more concerning than their parent antimicrobials. This review article explores the occurrence and fate of two of the most common legacy antimicrobials, triclosan and triclocarban, their metabolites/byproducts during wastewater and sludge treatment and their potential impacts on the environment. This article also explores the fate and transformation of emerging alternative antimicrobials and addresses some of the growing concerns regarding these compounds. This is becoming increasingly important as consumers and regulators alike shift away from legacy antimicrobials to alternative chemicals which may have similar environmental and human health concerns.     

Investigation of thermal comfort properties of electrospun thermoplastic polyurethane fiber coated knitted fabrics for wind-resistant clothing

The integration of nanofibers into conventional fabrics may open up new opportunities such as improving the comfort performance and thermal management properties of outdoor clothing. Nanofibers are able to form a highly porous mesh and their large surface-to-volume ratio improves performance for many applications. This study shows the possible utility of the nanofiber coating on conventional knitted fabrics for improving the wind-resistance and breathability properties. It was seen that nanofiber coating did not cause a significant effect on water vapor and thermal resistance of electrospun thermoplastic polyurethane nanofiber coated cotton (CO), modal (CMD), viscose (CV), and lyocell (CLY) single jersey fabrics, while resistance to air permeability was increased with the increased nanofiber coating. High level of air resistance was achieved with 30 min of coating. In terms of comfort properties, the nanofiber coating proved to be advantageous due to its lower air permeability with its water vapor permeable structure. However, thermal insulation level of these fabrics was still low and fragile nanofiber layer needed to be protected. Therefore, a multi-layered fabric form was derived from combination of cotton and lyocell fabrics with a nanofiber layer. The results showed that nanofibers could be used to improve the wind-resistance and comfort properties of multi-layered knitted structures.     

Athermal microwave effects for enhancing digestibility of waste activated sludge

A bench scale industrial microwave (MW) unit equipped with fiber optic temperature and pressure controls within pressure sealed vessels successfully simulated conventional heating (CH, in water bath). By identical temporal heat temperature profiles for waste activated sludge (WAS) samples, evaluation of the athermal effects of MW irradiation on WAS floc disintegration and anaerobic digestion was achieved. In a pretreatment range of 50-96 degrees C, both MW and CH WAS samples resulted in similar particulate chemical oxygen demand (COD) and biopolymer (protein and polysaccharide) solubilization and there was no discernable MW athermal effect on the COD solubilization of WAS. However, biochemical methane potential (BMP) tests showed improved biogas production for MW samples over CH samples indicating that the MW athermal effect had a positive impact on the mesophilic anaerobic biodegradability of WAS. BMP tests also showed that despite mild inhibition in the first 7d, MW acclimated inoculum digesting pretreated (to 96 degrees C) WAS, produced 16+/-4% higher biogas compared to the control after 15 d of mesophilic batch digestion. However, initial acute inhibition was more severe for non-acclimated inoculum requiring recovery time that was two times longer with only 4+/-0% higher biogas production after 17d. Inoculum acclimation not only accelerated the production of biogas, but also increased the extent of the ultimate mesophilic biodegradation of MW irradiated WAS (after 15-27 d).     

Phenolic composition,antioxidant, antibacterial,larvacidal against Culex pipiens,and cytotoxic activities of Hyacinthella lineata steudel extracts

This study reports the phenolic composition, antioxidant, antibacterial, larvacidal, and cytotoxic activity of methanol and acetone extracts of Hyacinthella lineata leaves and bulbs. The phenolic composition of H. lineata was determined by HPLC. The most abundant component was gallic acid (421.9µg/g). The β-carotene/DPPH/ABTS/FRAP decoloration method was used to estimate the total antioxidant activity. The total antioxidant activity was the highest for bulb-methanol fraction (65.41 ± 0.05%). The total phenolic content for leaves-methanol extract of the plant was determined as 6.56 ± 4.027mg/mL gallic acid equivalents. Analysis of the antibacterial activity showed that the methanolic-bulb extract are efficient against gram positive and gram negative bacteria. The cytotoxic effect on Artemia salina was assessed by Brine shrimp assay. Brine shrimp lethality assay showed that LC₅₀ values of HBM were obtained as 4.105 ± 2.42μg/ml. The bulb extract of H. lineata showed the highest larvicidal activity against Cx pipiens with value LC₅₀ (64.3275μg/ml). This study suggested that H. lineata may be used as a potential source of antioxidant, and for their biological activity, cytotoxic and antimicrobial properties.     

Sorption of heavy metal ions by glass beads-immobilized calix[4]arenes derivative

Glass beads (GB) immobilized, 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonylmethoxy-26,28-dihydroxycalix[4]arene (CA) are prepared and used as a new sorbent in sorption study of removal heavy metal ions. A calixarene derivative bonded to amino-functionalized glass beads sorbent was synthesized via a self assembly technique for sorbent of selected heavy metal ions in aqueous. In order to absorb selected heavy metal ions in aqueous, a calixarene derivative bonded to amino-functionalized glass beads sorbent was synthesized via a self assembly technique. The sorbent which is named GB-APTS-CA was characterized using infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), elemental analysis and thermal analysis (TGA/DTG). The influences of some experimental parameters including pH of the sample solution, weight of sorbent, concentration and temperature have been investigated. The sorption data were evaluated using the Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherm. The obtained maximum sorption capacity for Cu(II), and Pb(II) is 0.06 mmol g^?1 and 0.02 mmol g^?1, respectively. Thermodynamic parameters such as the standard free energy change (ΔG○), enthalpy change (ΔH○) and entropy change (ΔS○) were calculated to determine the nature of sorption process. Thus, GB-APTS-CA is favorable and useful for the removal of Cu(II) and Pb(II) metal ions.     

Epindolidiones—Versatile and Stable Hydrogen‐Bonded Pigments for Organic Field‐Effect Transistors and Light‐Emitting Diodes

Hydrogen‐bonded pigments are remarkably stable high‐crystal lattice energy organic solids. Here a lesser‐known family of compounds, the epindolidiones, which demonstrates electronic transport with extraordinary stability, even in highly demanding aqueous environments, is reported. Hole mobilities in the range 0.05–1 cm² V^–1 s^–1 can be achieved, with lower electron mobilities of up to 0.1 cm² V^–1 s^–1. To help understand charge transport in epindolidiones, X‐ray diffraction is used to solve the crystal structure of 2,8‐difluoroepindolidione and 2,8‐dichloroepindolidione. Both derivatives crystallize with a linear‐chain H‐bonding lattice featuring two‐dimensional π–π stacking. Powder diffraction indicates that the unsubstituted epindolidione has very similar crystallinity. All types of epindolidiones measured here display strong low‐energy optical emission originating from excimeric states, which coexists with higher‐energy fluorescence. This can be exploited in light‐emitting diodes, which show the same hybrid singlet and low‐energy excimer electroluminescence. Low‐voltage FETs are fabricated with epindolidione, which operate reliably under repeated cyclic tests in different ionic solutions within the pH range 3–10 without degradation. Finally, in order to overcome the insolubility of epindolidiones in organic solvents, a chemical procedure is devised to allow solution‐processing via the introduction of suitable thermolabile solubilizing groups. This work shows the versatile potential of epindolidione pigments for electronics applications.     

Selection of psychrotrophic Leuconostoc spp. from native fruits, and studies on their dextransucrases

Present study was aimed at selection of psychrotrophic Leuconostoc spp., having dextransucrase activity from native fruits and sauerkraut. Fifty-six colonies of lactic acid bacteria producing dextransucrase were isolated and characterized by physiological-biochemical methods. Seven isolates with high dextransucrase activities (0.68–1.63 IU/mL) were studied in detail including characterization by 16S rDNA sequence comparison. It was found that these isolates grow faster and produced dextransucrase earlier than Leuconostoc mesenteroides B512FMC-13Glc, a mutant form of the commercial strain. Molecular weights of the dextransucrases produced by 7 isolates were determined and acceptor reactions using maltose were studied. Dextranase hydrolysis products of dextrans produced by new enzymes were similar to those of commercially produced B-512 F dextran. The new dextransucrases could find industrial uses and the strains isolated (AN 39-1, Or2p-2, Mu3, and Mu10) could be used as prebiotic producing starters in food fermentations due to having high dextransucrase activity and their growth at 4°C.