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Amino trimethylene phosphonic acid (ATMP) was widely used as an antiscalant in reverse osmosis (RO) systems to prevent membrane scaling, and entered RO concentrate at elevated levels. However, phosphonate antiscalants in RO concentrate might aggravate phosphorus pollution, remobilize heavy metals, and adversely affect the sedimentation treatment of RO concentrate. Ozonation was found an efficient method for ATMP treatment. The ATMP removal efficiencies with 8 mg/L ozone were 100% and 86.5% for ultrapure water and RO concentrate, respectively. The ATMP mineralization efficiency reached 46.5% with 8 mg/L ozone. The rate constant for the reaction between ATMP and ozone was 1.92 × 106 M−1 s−1. Increasing the pH from 3 to 9 decreased the ATMP removal efficiency from 90% to 30.9% but increased the orthophosphate formation to ATMP removal ratio from 0.11 to 0.48. The ATMP intermediates generated with low ozone dosages exhibited moderate chelation and anti-precipitation capacity, and their chelation and anti-precipitation capacity could be further attenuated by increasing the ozone dosage. Ozonation alone enhanced the growth potential for microalgae in RO concentrate because orthophosphate formed. Combining ozonation and coagulation effectively removed 83.0% of the total phosphorus from RO concentrate. The maximum algal density of Scenedesmus sp. LX1 decreased by 78.7% by ozonation and coagulation.

Dodecyltrimethylammonium chloride (DTAC) is a quaternary ammonium compound (QAC) that is a widespread contaminant in environmental media and therefore of increasing concern. The synergistic effect with UV irradiation and persulfate (UV/PS) was used to degrade DTAC. The removal of DTAC was 91% with the PS dosage of 75.6 μM (UV/PS) and UV fluence of 870 mJ·cm−2. The second-order rate constants of DTAC with HO and SO 4− were determined to be kHO , DTAC (4.2 ± 0.18) × 109 M−1 s−1 and kSO4∙−, DTAC (2.5 ± 0.27) × 109 M−1 s−1, respectively. The contributions of HO and SO 4− to DTAC degradation in the UV/PS were found to be 30% and 62% at pH 7, respectively. The contributions of SO 4− and HO were not significantly influenced by acidic medium (pH 3–pH 7), whereas they were significantly affected by basic medium (pH 7–pH 11). The wastewater matrixes of HCO3−, Cl− and humic acid inhibited the DTAC elimination, whereas NO3− and SO42− had no significant impact on its elimination. Moreover, the kobs,DTAC in the reverse osmosis influent (ROI) and reverse osmosis concentrate (ROC) were examined to be 0.04 to 0.1 min−1 and 0.02 to 0.05 min−1, respectively, as the PS dosage increased from 18.9 to 113.4 μM. The inhibitive effects of matrix in ROI and ROC was 70% and 81%, respectively. The contribution of radical scavenging effect by matrix ROI and ROC was more significant to DTAC degradation than UV scattering effect in ROI and ROC matrices. A UV fluence of 1305 mJ·cm−2 was necessitated for complete detoxification and DTAC solution by UV/PS.

Background: Activins and inhibins are structurally related dimeric glycoprotein hormones belonging to the transforming growth factor-β superfamily but whether they are also involved in malignancy is far from clear. No study has reported the expression of INHBE in kidney cancer. The purpose of this study was to examine the expressions of INHBE in the tumor tissue of patients with clear-cell renal cell carcinoma (ccRCC) and to explore the pathologic significance. Methods: The INHBE mRNA expression in the tumor tissue of ccRCC patients was analyzed by using RNA sequencing data from the TCGA database. To examine the expression of inhibin βE protein, 241 ccRCC patients were recruited and immunohistochemistry was performed on the tumor tissue of these patients along with 39 normal renal samples. The association between the inhibin βE expression level and patient’s clinicopathological indices was evaluated. Results: In the normal renal tissue, inhibin βE was found to be expressed mainly by renal tubular epithelial cells. In the tumor tissue, inhibin βE was expressed mainly in cancer cells. The expressions of INHBE mRNA and protein in the tumor tissue of ccRCC patients increased significantly compared with those in normal renal samples. There was a significant correlation between the level of inhibin βE in the tumor tissue and tumor grade. Patients with a lower inhibin βE expression in the tumor tissue were found to have a longer overall survival and disease-specific survival. Conclusions: INHBE might be involved in the pathogenesis of ccRCC and function as a tumor promoter.

In this study, it was found that monochloramine induced the formation of reactive species during ozonation of chloromethylisothiazolinone (CMIT). CMIT was found recalcitrant to chloramine. However, chloramine promoted the degradation of CMIT by ozonation significantly. Hydroxyl radicals contributed most to CMIT degradation (87%) during ozone/chloramine synergistic oxidation process (SOP). The hydroxyl radical exposure during ozone/chloramine SOP was around 7.9 times higher than that of ozonation process. The hydroxyl radical yield of ozone/chloramine SOP was estimated to be 32%. The reaction mechanisms between ozone and chloramine were postulated to include the oxygen transfer reaction to form singlet oxygen, and the formation of hydroxyl radical by the insertion pathway or electron transfer pathway. Chloramine dosage and pH are essential influencing factors. The degradation of CMIT increased from 41% to 74% with increasing chloramine dosage (0–20 μM), and then decreased to 65% when chloramine dosage continually increased to 40 μM. Ozone/chloramine SOP showed better performance at acidic or neutral conditions than basic condition. Based on the intermediates identified, the degradation pathway of CMIT during ozone/chloramine SOP included the oxidation of sulfur atom and the substitution of chlorine group by hydroxyl group. The oxidation of sulfur atom induced lower toxicities of transformation products. The toxicities of hydroxylation products were lower to fish and algae, but higher to daphnia. Based on the GC-ECD results, only trichloromethane (1.94 μg/L) was detected after ozone/chloramine SOP, accounting for 0.17% (μM/μM) of the CMIT removal.

2-Phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) is an antiscalant that is widely used in reverse osmosis (RO) systems. Because of its high concentration in RO concentrate, eutrophication risk and anti-precipitation properties may affect subsequent treatments, therefore treatment strategies are needed to eliminate such substances. In this study, PBTCA was degraded by ozonation. The results show that PBTCA reacted with ozone molecules and hydroxyl radicals, with second-order rate constants of (0.12 ± 0.002) and (7.83 ± 1.51) × 108 L mol−1 s−1, respectively. The phosphorus in PBTCA (PP) was transformed into organic phosphorus except for PBTCA (PO), and inorganic phosphorus (PI); PO was further transformed into PI. The changes in the concentrations of these phosphorus forms were investigated by model simulation. Simulation showed that the rate of PP transformation into PO was 5.5 times higher than that into PI. PBTCA was ozonated much faster at alkaline pH than at acidic pH. This is ascribed to different amounts of ozone molecules and hydroxyl radicals, and their different reaction rates with PBTCA. Furthermore, anti-precipitation property was reduced during ozonation, as shown by the amounts and morphology changes of the precipitates. PBTCA concentration for 50% anti-precipitation (AP50) did not change during ozonation, indicating that the transformation products generated during ozonation did not have anti-precipitation effects. Phosphorus in PBTCA was removed by ozonation–coagulation treatment. Total phosphorus and inorganic phosphorus were removed efficiently by using ferric chloride as a coagulant. The coagulants tended to bind with inorganic phosphorus to form flocs. Meanwhile, flocs were more easily to aggregate and precipitate as anti-precipitation effect was gradually removed, thus more phosphorus was removed. A combination of ozonation and coagulation removed PBTCA effectively and simultaneously reduced its anti-precipitation property and phosphorus.

Dodecyl dimethyl benzyl ammonium chloride (DDBAC), a non-oxidizing biocide, is commonly used in municipal wastewater reverse osmosis system. It has been used also as an ingredient in fabric softeners, disinfectants, detergents, phase transfer agent and numerous personal skin care products. In this study, the DDBAC degradation efficiency achieved using UV and persulfate (PS) oxidation processes was investigated. Substantial synergistic effects on DDBAC degradation were found when UV and PS oxidation processes were combined. During the UV/PS process, UV photolysis and reactions with radical species accounted for 42.7% and 57.3%, respectively, of DDBAC degradation. The OH and SO4 − radicals accounted for 4.6% and 52.7%, respectively, of DDBAC degradation. The calculated k OH,DDBAC and k SO 4 - ,DDBAC rate constants were (1.45 ± 0.16) × 109 and (1.51 ± 0.02) × 109 M−1 s−1, respectively. The kobs rate constant for DDBAC degradation increased from 0.047 to 0.150 min−1 when the PS dose was increased from 0.05 to 1.45 mM. The presence of natural organic matter (NOM), HCO3−/CO32−, and NO3− adversely affected DDBAC degradation. Five main intermediates were identified by high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry. The proposed DDBAC degradation pathway involves benzyl-nitrogen bond cleavage (or subtraction of hydrogen from the alkyl chain), demethylation, hydroxylation, and hydrogen subtraction. UV/PS treatment decreased the acute toxicity of the DDBAC solution in less than 15 min. However, the residual toxicity indicated that toxic oxidation transformation products were formed when DDBAC was treated using the UV/PS process.

UV based advanced oxidation processes (UV-AOPs) that efficiently eliminate organic pollutants during water treatment have been the subject of numerous investigations. Most organic pollutants are not completely mineralized during UV-AOPs but are partially oxidized into transformation products (TPs), thereby adding complexity to the treated water and posing risks to humans, ecological systems, and the environment. While the degradation kinetics and mechanisms of pollutants have been widely documented, there is little information about the risks associated with TPs. In this review, we have collated recent knowledge about the harmful TPs that are generated in UV/H2O2 and UV photocatalysis, two UV-AOPs that have been studied extensively. Toxic and assimilable TPs were ubiquitously observed in more than 80% of UV-AOPs of organic pollutants, of which the toxicity and assimilability levels changed with variations in the reaction conditions, such as the UV fluence and oxidant dosage. Previous studies and modeling assessments showed that toxic and assimilable TPs may be generated during hydroxylation, dealkylation, decarboxylation, and deamination. Among various reactions, TPs generated from dealkylation and decarboxylation were generally less and more toxic than the parent pollutants, respectively; TPs generated from decarboxylation and deamination were generally less and more assimilable than the parent pollutants, respectively. There is also potential concern about the sensory-unpleasant TPs generated by oxidations and subsequent metabolism of microorganisms. In this overview, we stress the need to include both the concentrations of organic pollutants and the evaluations of the risks from TPs for the quality assessments of the water treated by UV-AOPs.

The gamma degradation of toxic non-oxidizing biocide dodecyl dimethyl benzyl ammonium chloride (DDBAC) was investigated. The degradation of DDBAC achieved 70–100% depending on the initial concentration and the absorbed dose, but only 10–33% dissolved organic carbon was removed. The presence of NO3 −, HCO3 −, 2-propanol and tert-butanol inhibited the degradation of DDBAC. The DDBAC degradation rate constant ratios of ·OH, ·H and e aq − was calculated as 7.4:1.4:1. The acute toxicity of 10 mg L−1 DDBAC was removed by 60% at absorbed doses of 0.5–3.0 kGy. The results showed that gamma irradiation was effective to remove DDBAC and its toxicity.

Methylisothiazolinone (MIT) is a widely used non-oxidizing biocide for membrane biofouling control in reverse osmosis (RO) systems usually with high dosages. However, few investigations have focused on MIT removal through bio-processes, since it is highly bio-toxic. This study proposed a novel biotreatment approach for efficient MIT degradation by Scenedesmus sp. LX1, a microalga with strong resistance capability against extreme MIT toxicity. Results showed that MIT (3 mg/L) could be completely removed within 4 days’ cultivation with a half-life of only 0.79 d. Biodegradation was the primary removal mechanism and this metabolic process did not rely on bacterial consortia, soluble algal products secretion or algal growth. The main pathway was proposed as ring cleavage followed by methylation and carboxylation through the identification of MIT transformation products. MIT biodegradation followed the pseudo-first-order kinetics under growth control. A new kinetic model was presented to depict the MIT removal considering algal growth, and this model could be used for generally describing non-nutritive contaminants biodegradation. The algal biodegradation capability was independent of the initial biocide concentration, and MIT removal could be enhanced by increasing the initial algal density. Our results highlight the potential application of algal cultivation for MIT-containing wastewater biotreatment, such as RO concentrate.

This study was aimed to investigate the influence of low-frequency alternative pulse current (APC) with square wave on the disinfection performance of carbon fiber-based flow-through electrode system (FES) towards a model bacterium (Escherichia coli). The FES disinfection under direct current (DC) supply was limited by the weak disinfection efficiency of cathode. Compared with DC supply (less than 1 log removal), FES under APC supply achieved superior disinfection performance (over 6 log removal) at the voltage of 3 V and flow rate of 125 mL/min. The optimum condition was acquired when pulse cycle time (T) equaled to hydraulic retention time (HRT), i.e. HRT/T = 1, corresponding to the low frequency (less than 1 Hz), under which the disinfection performance was improved by alternating of anode and cathode. In-situ sampling experiments revealed that redox reactions were carried out alternatively in each electrode, and both electrodes made great contributions to disinfection under APC supply, which was significantly different from DC supply. In addition, FES disinfection under APC supply also caused irreversible damage to bacterial cells, resulting in no bacterial regrowth/reactivation during storage, and guaranteed low energy consumption (11.4 ~ 12.1 Wh/m3) with high flow rate (100 ~ 125 mL/min). Therefore, the development of a novel FES under APC supply provided exciting possibilities for future application of electrochemical disinfection to achieve superior disinfection performance with no bacterial regrowth and low energy consumption.

The effects of phosphonates, the heavily-used antiscalants in reverse osmosis systems, on microalgae are controversial, although they are harmless to most aquatic organisms. Herein, we assessed the inhibitory effects of etidronic acid (HEDP) and diethylenetriamine penta(methylene phosphonic acid) (DTPMP) on algal growth and revealed the mechanisms involved in both intrinsic toxicity and complexation. The phosphonates showed weak influences on Scenedesmus sp. LX1 in the first 4 d of cultivation. In contrast, a significant growth inhibition was observed subsequently with half maximal effective concentrations of 57.6 and 35.7 mg/L for HEDP and DTPMP, respectively, at 10 d. The phosphonates had little effect on cellular energy transfer and oxidative stress, quantified by adenosine triphosphate level and superoxide dismutase activity, respectively, demonstrating weak intrinsic toxicities to algal cells. Phosphonates blocked the algal assimilation of iron ions through complexation. Severe iron deficiency limited photosynthetic activity and caused chlorophyll decline, resulting in a functional loss of the photosystem followed by complete algal growth inhibition at the late cultivation stage. Our findings point to a potential ecological impact wherein harmful algal blooms are induced by the natural degradation of phosphonates due to the release of both iron and phosphate ions that stimulate algal regrowth after disinhibition.

Reverse osmosis concentrate (ROC) from municipal wastewater treatment contains high concentrations of complex toxic biorefractory pollutants. We studied the mechanisms by which two ultraviolet advanced oxidation processes, UV/H2O2 and UV/PS, degraded pollutants in ROC from municipal wastewater reclamation processes. Both technologies had similar removal efficiencies of bulk dissolved organic matter based on the observed reduction in COD, chromophores, and fluorophores. However, UV/PS decomposed both high and medium molecular weight (MW) fractions (57 and 67.7%), while UV/H2O2 preferentially decomposed only the high MW fraction (60 and 39.1%), suggesting that the two methods operate by different reaction mechanisms. The changes in electron donating capacity resulting from treatment by UV/H2O2 (42.3%) and UV/PS (75.2%) were different. SO4•− primarily decomposed compounds containing electron-donating groups better than •OH. The removal of dissolved organic matter by UV/PS resulted in decreases in both relative electron-donating capacity and relative specific ultraviolet absorbance. The distinct reaction mechanisms were observed between UV/PS and UV/H2O2, being that UV/PS preferentially decomposed the contaminants via electrophilic addition and hydroquinone generation, while UV/H2O2 preferentially decomposed the contaminants via phenolic-ring cleavage reactions. Changes in the UV absorbance (UVA254) and the fluorescence index (FI) were used to monitor the rate of elimination of toxic biocides in the ROC.

The disinfection performance of a carbon fiber-based flow-through electrode system (FES) towards Gram-negative bacteria (Escherichia coli and fecal coliform) and Gram-positive bacteria (Enterococcus faecalis and Bacillus subtilis) in normal saline was systematically investigated over a wide range of applied voltages (1–5 V) and hydraulic retention times (HRTs) (1–10 s). It was revealed that the Gram-negative bacteria were more vulnerable to FES for their thinner cell walls, and over 6.5 log removal (no live bacteria detected) was achieved at the applied voltage of 2 V and HRT of 2 s; while Gram-positive bacteria were inactivated at slightly higher voltages (3 V, 2 s) or longer HRTs (2 V, 5 s). Bacterial inactivation was attributed to the change and rupture of cell membrane mainly by anode direct oxidation without bacterial regrowth/reactivation. In addition, negligible generation of the free chlorine at low voltages (≤2 V) can avoid the formation of potential chlorinated disinfection byproducts (DBPs). Hence, FES can offer a potential alternative to conventional disinfection methods for bacterial inactivation in natural and contaminated water.

Methylisothiazolinone (MIT) is one of the most widely used non-oxidizing biocides, however its toxicity may pose a threat to ecosystems. A carbon fiber felt-based flow-through electrode system was used for MIT degradation in an aqueous solution. An excellent degradation rate (~90%) was achieved at a low applied cell voltage (2.5 V) and a high feed water flux (3 m3 h−1 m−2) that corresponds to a short resistance time of ~11 s. In-situ sampling experiments and electrochemical characterization indicated that MIT was degraded via a direct anodic oxidation mechanism. In terms of electrode sequence, anode–cathode system (by placing the anode upstream from the cathode) exhibited an improved MIT degradation performance and energy efficiency compared with a reversed cathode–anode system (by placing the anode downstream from the cathode), because the former arrangement prevented parasitic reactions and provided a higher anode potential. Effluent analysis by time-of-flight mass spectrometry and luminescent bacteria acute toxicity showed that the organic sulfur atom was oxidized to the sulfoxide or sulfone structure and then hydrolyzed to release from the MIT molecule, which led to a significant toxicity reduction. No obvious performance loss was observed over 5 h of continuous operation with a total treated MIT solution up to 1400 times the cell volume and an energy requirement of 0.03 kWh m−3. These promising data make the carbon fiber felt-based flow-through electrode system attractive for effective and low-cost water purification.

Reverse osmosis (RO) technology plays an increasingly important role in municipal wastewater reclamation. However, the antiscalants used in RO systems showed adverse effects to the ecosystem: impending the removal of hardness from RO concentrates; inducing phosphorus pollution in receiving water; enhancing the trace metal migration in the environment. In this study, UV/chlorine advanced oxidation process was used to oxidize a typical phosphoric antiscalant (1-Hydroxyethane-1, 1-diphosphonic Acid, HEDP). UV/chlorine showed significant synergetic effects on HEDP degradation compared to UV irradiation or chlorination alone. Compared to UV/H2O2 oxidation, UV/chlorine process is more efficient for HEDP transformation with chlorine dosages ranging from 0.1 to 0.4 mmoL/L. Chorine dosage showed dual effects on HEDP oxidation by UV/chlorine: the increasing trend of transformation efficiency of HEDP got slower with increasing chlorine dosage. The transformation efficiency of HEDP by UV/chlorine oxidation decreased from 39% to 14% with pH increasing from 4.5 to 9.0, likely due to the higher quantum yields and lower radical quenching rates of HOCl than those of OCl−. The transformation efficiency of HEDP decreased 14% and 42% with 30 mM of chloride and bicarbonate, respectively. The presence of nitrate promoted the oxidation of HEDP by UV/chlorine: the transformation efficiency increased 5% and 83% with the presence of 5 mM and 30 mM nitrate, respectively. Based on the static scale inhibition tests, UV/chlorine oxidation is effective at removing the scale inhibition ability of HEDP. During UV/chlorine process, the maximum scale inhibition ratio decreased from 66% to 34% as the removal of phosphonate ligand from HEDP increased to 80%.

UV based advanced oxidation processes (UV-AOPs) that efficiently eliminate organic pollutants during water treatment have been the subject of numerous investigations. Most organic pollutants are not completely mineralized during UV-AOPs but are partially oxidized into transformation products (TPs), thereby adding complexity to the treated water and posing risks to humans, ecological systems, and the environment. While the degradation kinetics and mechanisms of pollutants have been widely documented, there is little information about the risks associated with TPs. In this review, we have collated recent knowledge about the harmful TPs that are generated in UV/H

Reverse osmosis concentrate (ROC) generally contains highly toxic and biorefractory organic pollutants. In this study, various oxidation systems, including UV, persulfate (PS)/Cu2+, UV/PS, and UV/PS/Cu2+, were evaluated for the degradation of nonoxidizing biocides, which are commonly used in reverse osmosis systems for preventing biofouling. The results showed that UV/PS/Cu2+ had an enhancement effect among UV, PS, and Cu2+. Compared with UV/PS, the degradation efficiency of UV/PS/Cu2+ increased 4.4%–22.2% for dodecyl trimethyl ammonium chloride (DTAC) and 19%–37.6% for dodecyl dimethyl benzyl ammonium chloride (DDBAC). The kobs of DTAC and DDBAC by UV/PS/Cu2+ were approximately 1.5–2 times higher than those of the UV/PS system, which were examined to be 0.569 and 0.602 min−1, respectively. The contributions of SO4 −, HO , and other way on the degradation of DTAC and DDBAC in the UV/PS/Cu2+ system were observed to be 77.0%, 1.0%, and 22.1% for DTAC and 55.3%, 1.0%, and 12.0% for DDBAC, respectively, at pH 7. The effect of humic acids (HAs) and natural organic matter (NOM) considerably impeded the degradation of DTAC (50 and 54%) and DDBAC (47 and 69%) when the concentration of HAs and NOM was 1 and 10 mg/L, respectively. The degradation of DTAC by various metals was enhanced in the order Cu2+ > Fe2+ > Mg2+ > Mn2+ at 0.1 mg/L, whereas that of DDBAC was Cu2+ > Mg2+ > Zn2+ > Fe2+ > Mn2+.

Ozonation and chlorination are widely used for disinfection or micropollutant elimination in water treatment or reclamation fields. It was found in this study that the presence of free chlorine increased the production of reactive species significantly during ozonation of dodecylbenzyldimethylammonium chloride (DDBAC, quaternary ammonium compound). DDBAC hardly underwent degradation by the chlorination process. However, the removal of DDBAC by ozonation after 10 min increased from 22% to 92%, when the dosage of free chlorine increased from 0 to 112 mg/L. pH affected the synergistic effect of ozone/chlorine oxidation of DDBAC. The promotion effect of free chlorine was greater at acidic conditions than that at basic conditions. The radical quenching experiments suggested that various reactive species formed during ozone/chlorine oxidation of DDBAC. The contributions of ozone, reactive species that could or could not be quenched by tBuOH were 8%, 78% and 13%, respectively. In the mixed system of DDBAC and pCBA, the degradation percentage of DDBAC and pCBA after 15 min increased from 31.0% and 13.1% to 53.8% and 28.3% with the presence of chlorine, respectively. Based on the steady-state concentration assumption, the steady-state concentration of OH during ozone/chlorine oxidation of DDBAC was 2.3 times higher than that during the sole ozonation process, being 7.5 × 10−14 M and 3.3 × 10−14 M, respectively. Ten oxidation products were identified by HPLC-MS/MS during ozone/chlorine oxidation of DDBAC. Three degradation mechanisms were observed: the hydrogen abstraction of the alkyl chain by hydroxyl radical; the cleavage of the benzyl-nitrogen bond of DDBAC; and the addition of hydroxyl radical on the aromatic ring or the alkyl chain.

The disinfection performance of a flow-through electrode system (FES) was systematically evaluated using different carbonized (C1, C2, and C3) and corresponding graphitized (G1, G2, and G3) carbon fiber felt (CFF) electrodes. The physicochemical and electrochemical properties were characterized to identify the differences among CFFs. Graphitized CFFs (gCFFs) can achieve complete inactivation of Escherichia coli (>6 log) at the voltage of 3 V and flux of 120–3600 L/(m2 h) for high conductivity and chemical stability, while carbonized CFFs (cCFFs) only achieved around 1 log removal with obvious carbon corrosion. For the gCFFs, G1 (>6 log removal) with higher conductivity, better graphite structure, and larger surface area (related to fiber diameter and density) presented better disinfection performance at the flow rate of 30 mL/min than G2 (∼3 log) and G3(∼1 log). Furthermore, no regrowth and reactivation of bacteria occurred during the storage under visible light illumination after FES treatment. Three parallel FESs with G1 were operated continuously for one week (24 h per day, 7 days) treating the solution with an E. coli concentration ranging from 106 to 107 CFU/mL at the applied voltage of 3 V and the flow rate of 20 mL/min. No live bacteria were detected in the effluent of any of these three FESs. In-situ sampling experiments demonstrated that the inactivation of bacteria on anode was the dominant mechanism for FES treatment, which can be attributed to the sequential adsorption, direct-oxidation and desorption process on anode, instead of indirect oxidation by generating chemical oxidants. In addition, hydroxide ion generated from cathode reaction enhanced anode adsorption and inactivation of bacteria by providing alkaline environment. Combining the analysis results of material properties and disinfection performance, the gCFF-based FES was suggested to be a low-cost, high-efficiency, and safe alternative for future water disinfection.

The optimization design of gear transmission based on MATLAB is studied for the purpose of finding a convenient and practical method. A mathematical model of optimization design is established in order to minimize the volume of gear transmission, the sequential quadratic programming method (SQP) is used to solve the nonlinear constrained optimization problems. The method how to solve gear parameter optimization base on optimization toolbox of MATLAB is introduced in detail. An optimization design example is given, the optimization result accords with the standard specifications of mechanical design and can be directly used. The result shows that this method is convenient and effective, and can simplify computer programming, is especially suitable for engineer.

Catalysis was used to increase the H2 production, syngas heating value, enhanced carbon conversion efficiency and cold gas efficiency during gasification. Due to Cu and Zn were abundant in waste according to previous researches, this research discussed the effect of Cu and Zn on artificial waste gasification. The syngas composition and total lower heating value (LHV) were determined in this study. The results showed that the existence of Cu and Zn increased production of H2 and CO. However, the production of CH4 and CO2 decreased. At same time, total LHV was also increased. Additionally, the different Cu concentration affected gas composition and LHV, but the effect of Zn concentration was not significant.

A numerical investigation is presented of the structure of a displacement ventilation convection by using the Reynolds averaged Navier-Stokes equation and K-ε turbulence model. Numerical results are reported for the effect of Gr/Re2 on structure of indoor air convection and ventilation efficiency. The results show that the structure of indoor air convection changes from mechanical ventilation to natural ventilation, and the curves of ventilation efficiency are like “M” with Gr/Re2 increasing.