Highly efficient microbial inactivation enabled by tunneling charges injected through two-dimensional electronics.

Airborne pathogens retain prolonged infectious activity once attached to the indoor environment, posing a pervasive threat to public health. Conventional air filters suffer from ineffective inactivation of the physics-separated microorganisms, and the chemical-based antimicrobial materials face challenges of poor stability/efficiency and inefficient viral inactivation. We, therefore, developed a rapid, reliable antimicrobial method against the attached indoor bacteria/viruses using a large-scale tunneling charge-motivated disinfection device fabricated by directly dispersing monolayer graphene on insulators. Free charges can be stably immobilized under the monolayer graphene through the tunneling effect. The stored charges can motivate continuous electron loss of attached microorganisms for accelerated disinfection, overcoming the diffusion limitation of chemical disinfectants. Complete (>99.99%) and broad-spectrum disinfection was achieved <1 min of attachment to the scaled-up device (25 square centimeters), reliably for 72 hours at high temperature (60°C) and humidity (90%). This method can be readily applied to high-touch surfaces in indoor environments for pathogen control.

Genes that escape from X-chromosome inactivation and sexual dimorphism of systemic lupus erythematosus.

X chromosome inactivation can balance the effects of the two X chromosomes in females, and emerging evidence indicates that numerous genes on the inactivated X chromosome have the potential to evade inactivation. The mechanisms of escape include modification of DNA, RNA, histone, epitope, and various regulatory proteins, as well as the spatial structure of chromatin. The study of X chromosome inactivation escape has paved the way for investigating sex dimorphism in human diseases, particularly autoimmune diseases. It has been demonstrated that the presence of TLR7, CD40L, IRAK-1, CXCR3, and CXorf21 significantly contributes to the prevalence of SLE (systemic lupus erythematosus) in females. This article mainly reviews the molecular mechanisms underlying these genes that escape from X-chromosome inactivation and sexual dimorphism of systemic lupus erythematosus. Therefore, elucidating the molecular mechanisms underlying sexual dimorphism in SLE is not only crucial for diagnosing and treating the disease, but also holds theoretical significance in comprehensively understanding the development and regulatory mechanisms of the human immune system.

Reduction of byproduct formation and cytotoxicity to mammalian cells during post-chlorination by the combined pretreatment of ferrate(VI) and biochar.

Ferrate [Fe(VI)] can efficiently degrade various pollutants in wastewater. Biochar application can reduce resource use and waste emission. This study investigated the performance of Fe(VI)/biochar pretreatment to reduce disinfection byproducts (DBPs) and cytotoxicity to mammalian cells of wastewater during post-chlorination. Fe(VI)/biochar was more effective at inhibiting the cytotoxicity formation than Fe(VI) alone, reducing the cytotoxicity from 12.7 to 7.6 mg-phenol/L. The concentrations of total organic chlorine and total organic bromine decreased from 277 to 130 µg/L and from 51 to 39 µg/L, compared to the samples without pretreatment. Orbitrap ultra-high resolution mass spectrometry revealed that the number of molecules of DBPs decreased substantially from 517 to 229 by Fe(VI)/biochar, with the greatest reduction for phenols and highly unsaturated aliphatic compounds. In combination with the substantial reduction of 1Cl-DBPs and 2Cl-DBPs, 1Br-DBPs and 2Br-DBPs were also reduced. Fluorescence excitation-emission matrix coupled with parallel factor analysis suggested that fulvic acid-like substances and aromatic amino acid was obviously reduce likely due to the enhanced oxidation of Fe(IV)/Fe(V) produced by Fe(VI)/biochar and adsorption of biochar. Furthermore, the DBPs generated by electrophilic addition and electrophilic substitution of precursors were reduced. This study shows that Fe(VI)/biochar pretreatment can effectively reduce cytotoxicity formation during post-chlorination by transforming DBPs and their precursors.

Ultraviolet-based synergistic processes for wastewater disinfection: A review.

Ultraviolet (UV) irradiation is widely used for wastewater disinfection but suffers from low inactivation rates and can cause photoreactivation of microorganisms. Synergistic disinfection with UV and oxidants is promising for enhancing the inactivation performance. This review summarizes the inactivation effects on representative microorganisms by UV/hydrogen peroxide (H2O2), UV/ozone (O3), UV/persulfate (PS), UV/chlorine, and UV/chlorine dioxide (ClO2). UV synergistic processes perform better than UV or an oxidant alone. UV mainly attacks the DNA or RNA in microorganisms; the oxidants H2O2 and O3 mainly attack the cell walls, cell membranes, and other external structures; and HOCl and ClO2 enter cells and oxidize proteins and enzymes. Free radicals can have strong oxidation effects on cell walls, cell membranes, proteins, enzymes, and even DNA. At similar UV doses, the inactivation rates of Escherichia coli with UV alone, UV/H2O2, UV/O3, UV/PS (peroxydisulfate or peroxymonosulfate), and UV/chlorinated oxidant (chlorine, ClO2, and NH2Cl) range from 2.03 to 3.84 log, 2.62-4.30 log, 4.02-6.08 log, 2.93-5.07 log, and 3.78-6.55 log, respectively. The E. coli inactivation rates are in the order of UV/O3 ≈ UV/Cl2 > UV/PS > UV/H2O2. This order is closely related to the redox potentials of the oxidants and quantum yields of the radicals. UV synergistic disinfection processes inhibit photoreactivation of E. coli in the order of UV/O3 > UV/PS > UV/H2O2. The activation mechanisms and formation pathways of free radicals with different UV-based synergistic processes are presented. In addition to generating HO·, O3 can reduce the turbidity and chroma of wastewater to increase UV penetration, which improves the disinfection performance of UV/O3. This knowledge will be useful for further development of the UV-based synergistic disinfection processes.

Self-Powered Disinfection Using Triboelectric, Conductive Wires of Metal-Organic Frameworks.

Efficient water disinfection is vitally needed in rural and disaster-stricken areas lacking power supplies. However, conventional water disinfection methods strongly rely on external chemical input and reliable electricity. Herein, we present a self-powered water disinfection system using synergistic hydrogen peroxide (H2O2) assisted electroporation mechanisms driven by triboelectric nanogenerators (TENGs) that harvest electricity from the flow of water. The flow-driven TENG, assisted by power management systems, generates a controlled output with aimed voltages to drive a conductive metal-organic framework nanowire array for effective H2O2 generation and electroporation. The injured bacteria caused by electroporation can be further damaged by facile diffused H2O2 molecules at high throughput. A self-powered disinfection prototype enables complete disinfection (>99.9999% removal) over a wide range of flows up to 3.0 × 104 L/(m2 h) with low water flow thresholds (200 mL/min; ∼20 rpm). This rapid, self-powered water disinfection method is promising for pathogen control.

Degradation of antibiotics by electrochemical advanced oxidation processes (EAOPs): Performance, mechanisms, and perspectives.

Global consumption and discharge of antibiotics have led to the rapid development and spread of bacterial antibiotic resistance. Among treatment strategies, electrochemical advanced oxidation processes (EAOPs) are gaining popularity for treating water/wastewater containing antibiotics due to their high efficiency and easiness of operation. In this review, we summarize various forms of EAOPs that contribute to antibiotic degradation, including common electrochemical oxidation (EO), electrolyte enhanced EO, electro-Fenton (EF) processes, EF-like process, and EAOPs coupling with other processes. Then we assess the performance of various EAOPs in antibiotic degradation and discuss the influence of key factors, including electrode, initial concentration and type of antibiotic, operation conditions, electrolyte, and water quality. We also review mechanisms and degradation pathways of various antibiotics degradation by EAOPs, and address the species and toxicity of intermediates produced during antibiotics treatment. Finally, we highlight challenges and critical research needs to facilitate the application of EAOPs in antibiotic treatment.

Sensitivity of Ostracods to U, Cd and Cu: The Case of Cypridopsis vidua.

The development of uranium mines has been necessary to obtain abundant and scarce uranium resources, but they also bring inevitable radioactive contamination to the surrounding soil, rivers and lakes. This paper explores the sensitivity of Cypridopsis vidua to the radioactive element uranium and the heavy elements cadmium and copper with single and combined acute toxicity experiments and combined toxicity model predictions. The results from the single toxicity experiments showed that the degree of toxic effects was cadmium > copper > uranium. The combined toxicity experiments showed that the compound toxicity of U-Cd and U-Cu was higher than the weakest component and lower than the strongest component, whereas the compound toxicity of Cd-Cu was higher than either of its components. When the overall proportion of a more toxic metal was increased, its mixed toxicity also increased, and vice versa. Combined toxicity predictions showed that the U-Cd combination was best described by the concentration additive (CA) model, the independent action (IA) model was more applicable to the Cd-Cu combination, and the most applicable model for the U-Cu combination changed depending on the concentration gradient. The acute toxicity data from this study provide a reference for the development of wastewater discharge standards for uranium mines, enriches the data related to the toxicity of uranium for ostracods and deepens the understanding of the threat of uranium pollution to aquatic ecosystems.

Synergistic Nanowire-Enhanced Electroporation and Electrochlorination for Highly Efficient Water Disinfection.

Conventional water disinfection methods such as chlorination typically involve the generation of harmful disinfection byproducts and intensive chemical consumption. Emerging electroporation disinfection techniques using nanowire-enhanced local electric fields inactivate microbes by damaging their outer structures without byproduct formation or chemical dosing. However, this physical-based method suffers from a limited inactivation efficiency under high water flux due to an insufficient contact time. Herein, we integrate electrochlorination with nanowire-enhanced electroporation to achieve a synergistic flow-through process for efficient water disinfection targeting bacteria and viruses. Electroporation at the cathode induces sub-lethal damages on the microbial outer structures. Subsequently, electrogenerated active chlorine at the anode aggravates these electroporation-induced injuries to the level of lethal damage. This sequential flow-through disinfection system achieves complete disinfection (>6.0-log) under a very high water flux of 2.4 × 104 L/(m2 h) with an applied voltage of 2.0 V. This disinfection efficiency is 8 times faster than that of electroporation alone. Further, the specific energy consumption for the disinfection by this novel process is extremely low (8 × 10-4 kW h/m3). Our results demonstrate a promising method for rapid and energy-efficient water disinfection by coupling electroporation with electrochlorination to meet vital needs for pathogen elimination.

Photolysis of free chlorine and production of reactive radicals in the UV/chlorine system using polychromatic spectrum LEDs as UV sources.

Recently, ultraviolet light-emitting diodes (UV-LEDs) and chlorine combined system has been employed as an emerging advanced oxidation process. However, UV-LEDs were commonly considered as monochromatic UV sources. In this study, the obvious quantum yields of chlorine photolysis under 265 nm and 280 nm LEDs irradiations were investigated with treating LEDs as polychromatic UV sources. Particularly, Φobs-poly of HOCl and OCl⁻ for 265 nm LED were found to be 1.50 and 0.70 mol E-1, respectively, whereas Φobs-poly of HOCl and OCl⁻ for 280 nm LED were 1.28 and 0.64 mol E-1, respectively. It was identified that Φobs-poly were 5.66-14.63 % lower than Φobs-mono. This suggests that obvious quantum yield using peak emission wavelength would overestimate the true quantum yield. The production of radical species in LED UV/chlorine systems were determined by the degradation of BA, and illustrated by a mathematical model. Different trends were observed for 265 nm and 280 nm LED UV/chlorine systems as pH increased from 5.0 to 10.0. As pH increased, the formation of OH continuously decreased in both 265 nm and 280 nm LED systems. The formation of Cl increased at neutral pH and more Cl and OH were formed due to the higher molar absorbance coefficient at 280 nm. The chlorine dose-dependent effects on radical productions at pH of 5.0, 7.5 and 10.0 were also assessed. At pH of 5.0, OH was the main radical product and had linear correlation with chlorine dose. At pH of 7.5, the productions of OH and Cl showed similar profiles that increased rapidly at low chlorine dosage and then slowed down.

Emerging Energy Harvesting Materials and Devices for Self-Powered Water Disinfection.

Contaminated drinking water is one of the main pathogen transmission pathways making waterborne illnesses such as diarrheal diseases and gastroenteritis a huge threat to public health, especially in the areas where sanitation facilities and gird power are inadequate such as rural and disaster hit areas. Self-powered water disinfection systems are a promising solution in these cases. In this review paper, the authors provide an overview of the new and emerging methods of applying energy harvesting materials and devices as a source of power for water disinfection systems microbial disinfection in water by harnessing ambient forms of energy such as mechanical motion, light, and heat into electricity. The authors begin with a brief introduction of the different energy harvesting technologies commonly applied in water disinfection; triboelectric, piezoelectric, pyroelectric, and photovoltaic effects. Various microbial disinfection mechanisms and types of device construction are summarized. Then, a detailed discussion of the energy harvester-driven water disinfection process is provided. Finally, challenges and perspectives regarding the future development of self-powered water disinfection are described.

[Lycium barbarum polysaccharide reduces testicular spermatogenic injury in Immp2l－/－mice through GPX4 and AIF pathways].

OBJECTIVE: To investigate the protective effect of Lycium barbarum polysaccharide (LBP) against testicular spermatogenic injury in mice with oxidative stress (OS) and its mechanism. METHODS: A unique OS model was made in 1.5-month-old mice with mitochondrial inner membrane-like peptide-2 mutation (Immp2l－/－), which were fed with water (the negative control group) or LBP in water at the concentration of 20 mg/kg (the LBP intervention group), and wild-type Immp2l＋/＋ mice used as normal controls and fed with water only. Then all the mice were sacrificed at 13 months old and the testis tissue harvested for observation of pathological changes by HE staining, measurement of routine semen parameters, and detection of the apoptosis of spermatogenic cells by TUNEL and the expression levels of glutathione peroxidase 4 (GPX4) and apoptosis-inducing factor (AIF) by immunohistochemistry and Western blot. RESULTS: Thinned testicular cortex was observed in the negative controls, with evident vacuolar degeneration and reduced numbers of germ cells and elongated spermatids in the lumen of the seminiferous tubules, but all these pathological changes were improved and the germ cells at different levels orderly arranged in the LBP intervention group. Compared with the normal controls, the mice in the negative control group showed dramatically reduced sperm count (ï¼»72.89 ± 8.28ï¼½ vs ï¼»20.78 ± 1.45ï¼½ ×106, P<0.01) and the percentages of progressively motile sperm (PMS) (ï¼»58.62 ± 6.15ï¼½% vs ï¼»18.37 ± 2.67ï¼½%, P<0.01) and morphologically normal sperm (MNS) (ï¼»65.81 ± 7.69ï¼½% vs ï¼»20.33 ± 3.17ï¼½%, P<0.01) and increased apoptosis of spermatogenic cells (ï¼»1.45 ± 0.43ï¼½% vs ï¼»7.14 ± 0.78ï¼½%, P<0.01). LBP intervention, however, significantly increased the sperm count (ï¼»45.25 ± 3.39ï¼½ ×106, P<0.05), PMS (ï¼»36.34 ± 4.56ï¼½%, P<0.05) and MNS (ï¼»38.72 ± 3.63ï¼½%, P<0.05) and decreased the apoptosis of spermatogenic cells (ï¼»2.28 ± 0.07ï¼½%, P<0.01). The mice in the LBP intervention group, in comparison with the negative controls, exhibited remarkably up-regulated expression of GPX4 (2.75 ± 0.48 vs 1.43 ± 0.17, P<0.05) and down-regulated expression of AIF (2.43 ± 0.15 vs 1.35 ± 0.51, P<0.05). CONCLUSIONS: Lycium barbarum polysaccharide at 20 mg/kg can reduce testicular spermatogenic injury in Immp2l－/－ mice with oxidative stress through GPX4 and AIF pathways.

A Pan-Cancer Landscape of HOX-Related lncRNAs and Their Association With Prognosis and Tumor Microenvironment.

The highly conserved homology cassette family (HOX) as well as 18 referenced long non-coding antisense transcripts (HOXATs) play vital roles in the development of some cancers. Nevertheless, their expression patterns as well as their association with cancer prognosis and the tumor microenvironment (TME) in pan-cancers are still unclear. Here, based on public databases, the expression levels of HOXATs, their prognostic potentials, and correlation with tumor mutation burden (TMB), immune cell infiltration, immune subtype, immune response-related genes, and stemness scores corresponding to 33 tumor types were analyzed systematically using R language. The results of the analysis indicated that different cancer tissues show different HOXAT expression profiles. Further, HOXAT expression showed association with cancer prognosis and immune and stemness regulation. Gene set enrichment analysis also demonstrated that HOXATs participate in cancer- and immune-related pathways, and based on their expression levels, HOTAIRM1 and HOXB-AS1 showed potential involvement in oncogenesis as well as possible involvement in immune regulation across a variety of cancer types. Further investigation also confirmed a significantly higher expression of HOXB-AS1 in GBM than in lower grade glioma tissues. Importantly, in vitro cell function experiments indicated that HOXB-AS1 supports cancer stem cell and plays a fundamental role in glioma metastasis. In conclusion, our results provide valuable resources that can guide the investigation of the mechanisms related to the role of HOXATs in cancers as well as therapeutic analysis in this regard.

Solar-induced hybrid energy harvesters for advanced oxidation water treatment.

Water treatment based on advanced oxidation processes (AOPs) supplies clean water to rural areas lacking electric power supply and/or during natural disasters and pandemics. Considering the abundance of solar energy in the ambient environment, the solar-driven AOPs show an interesting potential to driving the water purification process. Involving the energy harvester (EH) that harvests mechanical or thermal energy into electricity to the solar-driven AOPs can achieve sustainable and self-powered water purification. Herein, we summarize the recent progress in the application of solar-induced hybrid EHs that harvest solar and mechanical/thermal energy simultaneously to drive AOP water treatment. A detailed discussion of the solar-induced hybrid EHs enabling AOP water treatment based on the mechanisms of piezo-, tribo-, pyro-, and thermo-assisted photocatalysis is provided. In addition, this paper explores future opportunities and strategies of the solar-induced hybrid EHs to drive the AOP water treatment in actual situations with unstable and fluctuating environmental conditions.

Evaluation of redevelopment priority of abandoned industrial and mining land based on heavy metal pollution.

Heavy metal contamination in soil is an important factor affecting the determination of safe redevelopment methods for industrial and mining land. In this paper, the soil environment of a typical mining city in northern China was taken as the research object, 148 surface soil samples were collected and the contents of heavy metals were measured. The health risk classification criteria for heavy metal contamination of soils and the method of priority assessment for redevelopment were used. The results showed that: the risk of potential utilization types of heavy metals in the abandoned industrial and mining land is different. When the utilization type is agricultural land, the soil environmental quality is good as a whole, and a small number of plots are polluted by cadmium (Cd)and mercury (Hg); When the land use type is construction land, the risk of heavy metal pollution comes from chromium (Cr); The priority of development in this study area is as follows: agricultural land > construction land > ecological land.

Triboelectrification induced self-powered microbial disinfection using nanowire-enhanced localized electric field.

Air-transmitted pathogens may cause severe epidemics showing huge threats to public health. Microbial inactivation in the air is essential, whereas the feasibility of existing air disinfection technologies meets challenges including only achieving physical separation but no inactivation, obvious pressure drops, and energy intensiveness. Here we report a rapid disinfection method toward air-transmitted bacteria and viruses using the nanowire-enhanced localized electric field to damage the outer structures of microbes. This air disinfection system is driven by a triboelectric nanogenerator that converts mechanical vibration to electricity effectively and achieves self-powered. Assisted by a rational design for the accelerated charging and trapping of microbes, this air disinfection system promotes microbial transport and achieves high performance: >99.99% microbial inactivation within 0.025 s in a fast airflow (2 m/s) while only causing low pressure drops (<24 Pa). This rapid, self-powered air disinfection method may fill the urgent need for air-transmitted microbial inactivation to protect public health.

Identification of therapeutic targets and prognostic biomarkers from the hnRNP family in invasive breast carcinoma.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA-binding proteins that are reported to play a crucial role in the pathogenic process of multiple malignancies. However, their expression patterns, clinical application significance and prognostic values in invasive breast carcinoma (BRCA) remain unknown. In this study, we investigated hnRNP family members in BRCA using accumulated data from Oncomine 4.5, UALCAN Web portal and other available databases. We explored the expression and prognostic value level of hnRNPs in BRCA. We further analyzed their association with the clinicopathological features of BRCA patients. Subsequently, we calculated the alteration frequency of hnRNPs, constructed the interaction network of hnRNPs, and examined the potential coexpression genes of hnRNPs, revealing that HNRNPU and SYNCRIP are the core molecular genes requiring further investigation for BRCA. We validated the immunohistochemistry (IHC) pattern to simulate clinical applications based on pathology. Cell function experiments conducted in vitro indicated that HNRNPU can promote epithelial-mesenchymal transition, functionally stimulating the invasion capacity and inhibiting the viability of invasive BRCA cells. In summary, our systematic analysis demonstrated that HNRNPU was the key molecule that played a fundamental role in BRCA metastasis, which may facilitate the development of new diagnostic and prognostic markers for the analysis of BRCA progression.

[Serum level of lncRNA TUSC7 in patients with esophageal squamous cell carcinoma and its role in promoting tumor cell migration and invasion].

OBJECTIVE: To investigate serum levels of long non-coding RNA (lncRNA) TUSC7 in patients with esophageal squamous cell carcinoma (ESCC), its association with clinicopathological parameters and its role in promoting tumor metastasis and invasion. METHODS: Serum samples were collected from 60 patients with ESCC admitted between January, 2017 and May, 2019, with 60 age- and gender-matched healthy subjects as the control group. Serum level of TUSC7 in ESCC patients and its expression in 4 ESCC cell lines was detected with RT-qPCR. The association of serum TUSC7 level with the clinicopathological features of the patients was analyzed. KYSE-30 cell models with TUSC7 overexpression or knockdown were established, and the proliferation of the cells was examined with MTT assay and their migration and invasion were assessed using wound healing and Transwell assays. Western blotting was used to detect the cellular expressions of the proteins associated with epithelial-mesenchymal transition (EMT). RESULTS: The patients with ESCC had significantly lower serum TUSC7 level than the healthy control subjects (P < 0.05). The ESCC cell lines also expressed lower levels of TUSC7 than normal cells (P < 0.05). Serum TUSC7 level was negatively correlated with tumor staging, lymph node metastasis and infiltration (P < 0.05) but was not significantly correlated with other clinicopathological parameters in ESCC patients. In the invitro cell experiment, overexpression of TUSC7 in KYSE-30 cells significantly inhibited cell migration and invasion (P < 0.05), enhanced the expression of the EMT marker protein E-cadherin and lowered the expressions of N-cadherin, Vimentin and MMP9 (P < 0.05); knocking down TUSC7 in the cells produced the opposite effects. CONCLUSIONS: The down-regulation of TUSC7 expression in the serum of ESCC patients and in ESCC cell lines is associated with the metastasis of ESCC and promotes tumor cell migration and invasion by promoting EMT, indicating the potential of serum TUSC7 level as a molecular marker for diagnosis, treatment and metastasis monitoring of ESCC.

Construction and optimization mechanisms of carbon fiber-based flow-through electrode system (FES) with stackable multi-cathode units for water disinfection.

The stackable carbon fiber-based flow-through systems (m(nC + 1A)) were constructed, where the multi-cathode units (nC + 1A) were equipped with multiple cathodes (nC) and a counter anode (1A), and the m was the stackable numbers of the nC + 1A units. The configuration of the m(nC + 1A) systems with m and n values from 1 to 6 was optimized by comparing their disinfection performance toward a model pathogen (Escherichia coli) from the aspects of disinfection ability, energy consumption and HRT. For multi-cathode units (nC + 1A), increasing the cathode numbers (n) promoted the E. coli inactivation by the predominant direct oxidation on the anode. Among the stackable m(nC + 1A) modules, the 3(3C + 1A) module was recommended as the best configuration. In the stackable 3(3C + 1A) module with consecutive reduction-oxidation processes, the E. coli inactivation mechanisms were attributed to the direct oxidation on the anodes and H2O2-induced indirect oxidation on the cathodes. The synergistic effect between the stackable 3C + 1A units promoted the electro-redox of the electrodes and their disinfection ability, which was also accompanied by the enhancement of energy consumption for O2/H2O2 mutual transformation on the electrodes. In turn, the modules with excessive stackable unit numbers (m > 3) over-promoted the competitive reaction of O2/H2O2 mutual transformation, restraining the disinfection performance.

Evaluation and prospects of nanomaterial-enabled innovative processes and devices for water disinfection: A state-of-the-art review.

This study provided an overview of established and emerging nanomaterial (NM)-enabled processes and devices for water disinfection for both centralized and decentralized systems. In addition to a discussion of major disinfection mechanisms, data on disinfection performance (shortest contact time for complete disinfection) and energy efficiency (electrical energy per order; EEO) were collected enabling assessments firstly for disinfection processes and then for disinfection devices. The NM-enabled electro-based disinfection process gained the highest disinfection efficiency with the lowest energy consumption compared with physical-based, peroxy-based, and photo-based disinfection processes owing to the unique disinfection mechanism and the direct mean of translating energy input to microbes. Among the established disinfection devices (e.g., the stirred, the plug-flow, and the flow-through reactor), the flow-through reactor with mesh/membrane or 3-dimensional porous electrodes showed the highest disinfection performance and energy efficiency attributed to its highest mass transfer efficiency. Additionally, we also summarized recent knowledge about current and potential NMs separation and recovery methods as well as electrode strengthening and optimization strategies. Magnetic separation and robust immobilization (anchoring and coating) are feasible strategies to prompt the practical application of NM-enabled disinfection devices. Magnetic separation effectively solved the problem for the separation of evenly distributed particle-sized NMs from microbial solution and robust immobilization increased the stability of NM-modified electrodes and prevented these electrodes from degradation by hydraulic detachment and/or electrochemical dissolution. Furthermore, the study of computational fluid dynamics (CFD) was capable of simulating NM-enabled devices, which showed great potential for system optimization and reactor expansion. In this overview, we stressed the need to concern not only the treatment performance and energy efficiency of NM-enabled disinfection processes and devices but also the overall feasibility of system construction and operation for practical application.

Effects of chlorine disinfection on the membrane fouling potential of bacterial strains isolated from fouled reverse osmosis membranes.

Biofouling of reverse osmosis (RO) membranes is an inevitable issue in wastewater reclamation and limits the application of RO systems. Chlorine disinfection is widely used as a pretreatment to control biofouling. However, the extracellular polymeric substances (EPS) and cellular inclusions released during chlorine disinfection might also cause membrane fouling. Furthermore, little is known regarding the chlorine resistance of bacterial strains found on fouled RO membranes. In this study, four bacterial strains isolated from fouled RO membranes were used as testing subjects to investigate the bacterial inactivation performance of chlorine disinfection. The effects of chlorine disinfection on the RO membrane fouling potential of these strains were also revealed. The chlorine resistance ability of Sphingopyxis sp. BM1-1 was strongest among the four strains as it secretes the highest amount of EPS per cell. The log inactivation efficiency of this strain was 1-log by 0.2 mg-Cl2/L in 30 min, which was one to three orders of magnitude lower than that of the other strains. Although chlorine disinfection inactivated most bacterial cells (>90%), the reaction with chlorine significantly increased the RO membrane fouling potential of all bacterial solutions. To elucidate the main mechanism behind the increase in the fouling potential, we further investigated the changes in the properties of EPS, and the release of EPS and cellular inclusions during chlorine disinfection. Chlorine disinfection did not significantly affect the RO membrane fouling potential of the EPS secreted by these bacterial strains. However, dissolved organic carbon (DOC), protein, polysaccharide, and DNA concentration of all bacterial solutions increased by one to nine times after chlorine disinfection. These results indicate that large amounts of EPS and cellular inclusions were released into the solutions after the reaction with chlorine, which was the main cause of the increase in RO membrane fouling potential of the bacterial solution after chlorine disinfection.