Promotion of Para-Chlorophenol Reduction and Extracellular Electron Transfer in an Anaerobic System at the Presence of Iron-Oxides

Anaerobic dechlorination of chlorophenols often subjects to their toxicity and recalcitrance, presenting low loading rate and poor degradation efficiency. In this study, in order to accelerate p-chlorophenol (p-CP) reduction and extracellular electron transfer in an anaerobic system, three iron-oxide nanoparticles, namely hematite, magnetite and ferrihydrite, were coupled into an anaerobic system, with the performance and underlying role of iron-oxide nanoparticles elucidated. The reductive dechlorination of p-CP was notably improved in the anaerobic systems coupled by hematite and magnetite, although ferrihydrite did not plays a positive role. Enhanced dechlorination of p-CP in hematite or magnetite coupled anaerobic system was linked to the obvious accumulation of acetate, lower oxidation–reduction potential and pH, which were beneficial for reductive dechlorination. Electron transfer could be enhanced by Fe2+/Fe3+ redox couple on the iron oxides surface formed through dissimilatory iron-reduction. This study demonstrated that the coupling of iron-oxide nanoparticles such as hematite and magnetite could be a promising alternative to the conventional anaerobic reduction process for the removal of CPs from wastewater

Defense mechanism of Fe(III)-assisted anammox under salt stress: Performance and microbial community dynamics

Anammox process has attracted attention due to its excellent nitrogen removal properties in nitrogen-rich wastewater treatment. However, there were some obstacles for the application of anammox to treat high saline wastewater due to its sensitivity to salinity. In this study, Fe(III) addition strategy was developed to assist anammox to adapt high saline surroundings, with the defense mechanism involved in Fe(III)-assisted anammox emphasized. Nitrogen removal performance of anammox was deteriorated at 3.5% salinity, with the average total nitrogen removal rate of 0.85 kg/(m3·d) observed. The continuous addition of Fe(III) could significantly assist anammox to resist high salinity through facilitating the enrichment of anammox species. Candidatus Kuenenia was the main anammox species and outcompeted Candidatus Brocadia under high saline surrounding. The relative abundance of Candidatus Kuenenia increased with increased salinity and reached 41.04% under 3.5% salinity. The synthesis of key enzymes of anammox species were improved through Fe(III) addition and then facilitated the energy metabolism of anammox bacteria under 3.5% salinity. This study provides a new thought in Fe(III)-assisted anammox enhancement technologies and deepens the insight of anammox in high saline wastewater treatment

Dehalogenation of iodinated x-ray contrast media in a bioelectrochemical system

Iodinated X-ray contrast media (ICM) are only to a limited extent removed from conventional wastewater treatment plants, due to their high recalcitrance. This work reports on the cathodic dehalogenation of the ICM iopromide in a bioelectrochemical system (BES), fed with acetate at the anode and iopromide at the cathode. When the granular graphite cathode potential was decreased from -500 to -850 mV vs standard hydrogen electrode (SHE), the iopromide removal and the iodide release rates increased from 0 to 4.62 ± 0.01 mmol m(-3) TCC d(-1) and 0 to 13.4 ± 0.16 mmol m(-3) TCC d(-1) (Total Cathodic Compartment, TCC) respectively. Correspondingly, the power consumption increased from 0.4 ± 1 to 20.5 ± 3.3 W m(-3) TCC. The Coulombic efficiency of the iopromide dehalogenation at the cathode was less than 1%, while the Coulombic efficiency of the acetate oxidation at the anode was lower than 50% at various granular graphite cathode potentials. The results suggest that iopromide could be completely dehalogenated in BESs when the granular graphite cathode potential was controlled at -800 mV vs SHE or lower. This finding was further confirmed using mass spectrometry to identify the dehalogenated intermediates and products of iopromide in BESs. Kinetic analysis indicates that iopromide dehalogenation in batch experiments can be described by a first-order model at various cathode potentials. This work demonstrates that the BESs have a potential for efficient dehalogenation of ICM from wastewater or environmental streams

Fabrication of ordered mesoporous carbon hollow fiber membranes via a confined soft templating approach

Ordered mesoporous carbon (OMC) membranes have broad applications such as size exclusion separation of molecules. In this work, a new method to prepare OMC hollow fiber membranes through a confined soft templating route is developed. In this method, commercialized polymeric hollow fiber ultrafiltration membranes were immersed in an ethanol solution containing a phenolic resin and a Pluronic triblock copolymer. Upon solvent evaporation, the phenolic resin and the surfactant self-assembled into the confined voids of the ultrafiltration membrane. After drying and pyrolysis, OMC hollow fiber membranes were obtained. The OMC hollow fiber membranes possess continuous membrane walls with an average thickness of 113 μm. The membrane wall has a hierarchical pore structure: one coming from hexagonally ordered mesoporous carbon with a pore diameter of ∼4.3 nm and the other being disordered defect holes with a size of 8-50 nm randomly distributed inside the OMC matrix. The gas permeance results indicate that the OMC hollow fiber membranes exhibit Knudsen diffusion behavior confirming their good quality

Bioelectrochemical system for recalcitrant p-nitrophenol removal

Bioelectrochemical system (BES) for recalcitrant p-nitrophenol (PNP) removal was investigated in this study. Effective removal of PNP at rates up to 9.14±0.48molm d was achieved at an energy consumption as low as 0.010±0.002kWhmol PNP. PNP removal rate was enhanced with negative cathode potential, increased influent PNP concentration and shortened hydraulic retention time (HRT). Although the coulombic efficiencies at the anode did not exceed 40%, coulombic efficiencies for PNP removal at the cathode were above 70% at various cathode potentials. Compared with conventional anaerobic process, the cosubstrate dosage in BES was significantly reduced due to the high coulombic efficiencies at the cathode. p-Aminophenol (PAP) was identified as the dominant product of PNP reduction at the abiotic graphite cathode of BESs. This study demonstrated that the BES had a potential for efficient removal of nitrophenol pollutants from wastewater

Nitrogen-Doped Hollow Mesoporous Carbon Spheres for Efficient Water Desalination by Capacitive Deionization

Water desalination performance of capacitive deionization (CDI) largely depends on electrode materials properties. Rational design and regulation of the structure and composition of electrode materials to acquire high CDI performance is of great significance. Herein, nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) were investigated as electrode material for CDI application. To understand the effect of structure and composition on CDI performance, another two CDI electrode materials, i.e., hollow mesoporous carbon spheres (HMCSs) and solid mesoporous carbon spheres (SMCSs) were prepared for comparison. The obtained N-HMCSs possessed unique hollow cavity and excellent nitrogen doping property, resulting in fast ion diffusion, good charge transfers ability and fine wettability. Compared with HMCSs and SMCSs electrodes, N-HMCSs electrode exhibited an improved electrosorption capacity and rate, demonstrating the dependence of CDI performance on the synergistic effect of hollow structure and nitrogen doping property. N-HMCSs electrode also present excellent cycle stability over 20 adsorption–desorption cycles. These results indicate the promising prospect of N-HMCSs for CDI application

Organophosphate Ester, 2-Ethylhexyl Diphenyl Phosphate (EHDPP), Elicits Cytotoxic and Transcriptomic Effects in Chicken Embryonic Hepatocytes and Its Biotransformation Profile Compared to Humans

The effects of 2-ethylhexyl diphenyl phosphate (EHDPP) on cytotoxicity and mRNA expression, as well as its metabolism, were investigated using a chicken embryonic hepatocyte (CEH) assay. After incubation for 36 h, the lethal concentration 50 (LC50) was 50 ± 11 μM, suggesting that EHDPP is one of a small cohort of highly toxic organophosphate esters (OPEs). By use of a ToxChip polymerase chain reaction (PCR) array, we report modulation of 6, 11, or 16/43 genes in CEH following exposure to 0.1, 1, or 10 μM EHDPP, respective