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A high quality of activated-carbon electrode materials is of great importance for improving the electrochemical performance of desalination in membrane capacitive deionization. In this study, porous activated carbon was prepared by pyrolytic carbonization and chemical activation of lignocellulosic loofa sponge (Luffa cylindrica, LS) to act as a carbonaceous electrode. After activation, a hierarchically porous structure formed, characterized by the generation of micro-/mesopores on the channel walls. The total specific surface area and pore volume of the activated carbon material rose as the alkali/char ratio increased. The LS-based carbon electrode LSCK14, referring to the activation product produced with a KOH/char ratio of 4, displayed excellent electrochemical behavior, characterized by a remarkable specific capacitance of 93.0 F g-1 at 5 mV s-1 in 1 M NaCl solution, as well as extraordinary reversibility for capacitive charge storage. Moreover, the electrosorption capacity was investigated in batch-mode membrane capacitive deionization at 1.0 V while treating a 10 mM NaCl electrolyte. As demonstrated, the LSCK14 activated carbon electrode presented a superior electrosorption capacity of 22.5 mg g-1. The improved capacitor characteristics and high electrosorptive performance of this material can be attributed to its unique porous characteristics (high surface area, micrometer-scale channels and both meso- and micropores). Consequently, activated carbons derived from resource-recovered LS, which combine a multi-channeled structure, mesopores and micropores, were demonstrated to be a promising electrode material for electrochemical water desalination.

Bacterial degradation plays a vital role in determining the environmental fate of micropollutants like triclocarban. The mechanism of triclocarban degradation by pure bacterium is not yet explored. The purpose of this study was to identify metabolic pathway that might be involved in bacterial degradation of triclocarban. Triclosan-degrading Sphingomonas sp. strain YL-JM2C was first found to degrade up to 35% of triclocarban (4 mg L(-1)) within 5 d. Gas chromatography-mass spectrometry detected 3,4-dichloroaniline, 4-chloroaniline and 4-chlorocatechol as the major metabolites of the triclocarban degradation. Furthermore, total organic carbon results confirmed that the intermediates, 3,4-dichloroaniline (4 mg L(-1)) and 4-chloroaniline (4 mg L(-1)) could be degraded up to 77% and 80% by strain YL-JM2C within 5 d.

We investigated the occurrence, removal and mass balance of 8 endocrine disrupting compounds (EDCs), including estrone (E1), estradiol (E2), estriol (E3), ethinylestradiol (EE2), triclosan (TCS), triclocarbon (TCC), 4-n-nonyl phenol (NP) and 4-n-octyl phenol (OP), along with 5 of their transformation products (TPs), including 4-hydroxy estrone (4-OH E1), 4-hydroxy estradiol (4-OH E2), methyl triclosan (MeTCS), carbanilide (NCC), dichlorocarbanilide (DCC) in a wastewater treatment plant. Generally, E3 showed the highest concentrations in wastewater with median value of 514 ng/L in influent, while TCS and TCC showed highest level in sludge and suspended solids (SS) with median value of 960 and 724 μg/kg, respectively. Spatial variations were observed along each unit of the wastewater treatment processes for dissolved analytes in wastewater and adsorbed analytes in suspended solids and sludge. Special emphasis was placed to understand the mass load of EDCs and their TPs to the wastewater treatment unit and mass loss during the wastewater treatment processes. Mass loss based on both aqueous and suspended phase concentration revealed that majority of these chemicals were significantly removed during the treatment process except for TCS, TCC, and three of their TPs (MeTCS, NCC, DCC), which were released or generated during the treatment process. Mass load results showed that 42.4 g of these EDCs and their TPs entered this wastewater treatment system daily via influent, whereas 6.15 g and 7.60 g were discharged through effluent and sludge.

Contamination of steroidal estrogens in the environment has raised a great public concern, and therefore, developing an effective method for removal of trace amount of environmental estrogens is necessary. In this study, two estrogen-degrading bacteria were isolated from activated sludge and were identified as strain Sphingomonas sp. AHC-F and strain Sphingobium sp. AX-B. They were capable of utilizing estrone (E1) and 17s-estradiol (E2) as sole carbon and energy source. Cell immobilization technique was applied to these two estrogen-degrading bacteria. Confocal laser-scanning microscopy images with live and dead staining of entrapped bacterial cells showed that most bacteria were present inside the porous structure and were mostly viable after immobilization procedures. Batch estrogen degradation study showed that immobilized strains AHC-F and AX-B could effectively degrade 2 mg/L of E2 and its metabolite E1. Immobilized bacteria column reactors using pure culture of strain AHC-F were set up for continuous-flow removal of 850 ng/L of E2 in the influent. The removal efficiency of E2 and equivalent estrogenic quantity of E2 (EEQ) could achieve 94 and 87% under 12 h hydraulic retention time (HRT), respectively. Increasing HRT could further improve the removal efficiency of EEQ. When the HRT increased to 72 h, the effluent concentrations of E2 and E1 were not detectable by gas chromatography-mass spectrometry. Our results also proved that most of the estrogen removal was due to biodegradation. This study has demonstrated the potential use of immobilized bacteria technique for the removal of environmental estrogens.

This study investigated the dissolution, aggregation, and reaction kinetics of silver nanoparticles (AgNPs) with the three types of water disinfectants (ultraviolet, sodium hypochlorite, and ozone) under the different conditions of pH, ionic strength, or humic acid (HA). The physicochemical changes of AgNPs were measured by using UV–Vis spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometer. The results showed that when AgNPs contacted the disinfectants, oxidative dissolution was the primary reaction. In addition, the reaction kinetics studies revealed that the reaction rate of AgNPs with disinfectants was significantly influenced by different disinfectants along with different pH and the presence of sodium nitrate and HA. Our research demonstrated the potential effect of disinfectants on AgNPs, which will improve our understanding of the fate of AgNPs in the disinfection processes in the water and wastewater treatment plant.

Steroidal estrogens, widespread in the environment, are contaminants of potential concern because exposure to these compounds can cause adverse impacts on aquatic life. Intensive research efforts have been undertaken in order to better understand the environmental occurrence of these compounds. In addition to physical/chemical reactions, biological processes – microbial biodegradation of steroidal estrogens – play a vital role in determining the fate and transport of these compounds in built and natural environments. This review summarizes the current state of knowledge on the microbiology of estrogen biodegradation. Aerobic and anaerobic estrogen-degrading microorganisms are phylogenetically diverse; they are mainly isolated from soils, activated sludge, dental plaque and intestines. Estrogens can be degraded via growth-linked and non-growth-linked reactions, as well as through abiotic degradation in the presence of selective microorganisms. Current knowledge on estrogen biodegradation kinetics and pathways is limited. Molecular methods are useful in deciphering estrogen-degrading microbial community and tracking the quantity of known degraders in bioreactors with different operating conditions. Future research efforts aimed at bridging knowledge gaps on estrogen biodegradation are also proposed.

In this study, Nitrosomonas europaea ATCC 19718 was exposed to silver nanoparticles (AgNPs) of different particle size (7 ± 3 and 40 ± 14 nm) and different coatings (polyvinyl alcohol and adenosine triphosphate disodium). For all different AgNPs used in the study, large aggregates were gradually formed after addition of AgNPs into the media containing N. europaea . The scanning electron microscopy and energy dispersive X-ray spectroscopy of the microstructures suggested that bacterial cells and electrolytes had significant effects on AgNP aggregation. Size- and coating-dependent inhibition of ammonia oxidation by AgNPs was observed, and our analysis suggested that the inhibition was not only due to the released dissolved silver, but also the dispersity of AgNPs in the culture media. Electron microscopy images showed AgNPs could cause the damage of cell wall of N. europaea and make the nucleoids disintegrated and condensed next to cell membrane. Surface-enhanced Raman scattering signals also implied the damage of cell membrane caused by AgNPs. Further protein expression analysis revealed that AgNPs would inhibit important protein functions, including biosynthesis, gene expression, energy production and nitrification to further cause toxicity to N. europaea . Our findings explain the susceptibility of N. europaea to inhibition by AgNPs and the possible interaction between each other. Future research is needed to characterize these effects in more complex cultures and media such as activated sludge and wastewater.

This study examined the biodegradation potential of three wastewater micropollutants (triclosan, bisphenol A, and ibuprofen) by Nitrosomonas europaea and mixed ammonia-oxidizing bacteria in nitrifying activated sludge. N. europaea could degrade triclosan and bisphenol A, but not ibuprofen. The degradation was observed only in the absence of allylthiourea (an inhibitor for ammonia monooxygenase (AMO)), suggesting that AMO might be responsible for triclosan and bisphenol A degradation. Competitive inhibition among ammonia, triclosan, and bisphenol A was observed. Inactivation of N. europaea was observed after degrading a mixture of triclosan and bisphenol A. The inactivation might be due to product toxicity and/or antimicrobial effect of triclosan; however, the causes of the inactivation were not determined. Regardless of the presence of the AMO inhibitor, three micropollutants were degraded by two different nitrified activated sludge samples. The results suggested that both ammonia-oxidizing bacteria and heterotrophic microorganisms in the activated sludge can degrade triclosan and bisphenol A. On the other hand, ibuprofen was more likely degraded by heterotrophic microorganisms in the activated sludge.

Presence of pharmaceuticals and personal care products (PPCPs) in the environment has received a great attention due to their potential impacts on public health. This study examined the occurrence of PPCPs in West Prong Little Pigeon River in east Tennessee. As wastewater is a major source for environmental occurrence of PPCPs, both wastewater and river water samples were analyzed for nine target PPCPs and their estrogenicity. No estrogens were detected in influent, secondary effluent, and river samples. However, ibuprofen, caffeine, triclosan, bisphenol A, and bis(2-ethylhexyl)phthalate (DEHP) were detected in the influent. Ibuprofen, triclosan, and DEHP were detected in the secondary effluent samples. Only ibuprofen and triclosan were detected in river water collected near a wastewater outfall. Based on yeast estrogenic screening (YES) assays, estrogenic activities were observed in all influent, secondary effluent, and river water samples. Increased estrogenic activities were observed in river right after receiving effluent discharge, and the activities decreased as river water flowing away from the outfall. The estrogenicities of water samples measured from YES assays were much higher than those estimated from PPCP concentrations and their known estrogenicities, suggesting the presence of other unknown estrogenic compounds and/or additive effects of mixtures of estrogenic compounds at low concentrations. Results of this study demonstrated that wastewater contributed to environmental occurrence of PPCPs in the receiving water. As there is a myriad of known and unknown PPCPs in wastewater, in additional to chemical analysis, estrogenic bioassays are needed for assessing estrogenicity of environmental samples.