查看更多>>摘要：Magnetic field, acknowledged as a sustainable approach, is a promising method to improve the formation, stability and treatment performance of aerobic granular sludge (AGS). In this study, partial nitrification-denitrification was achieved in three AGS sequencing batch reactors (SBRs), and the effect of magnetic field intensity on AGS formation and partial nitrification-denitrification performance were investigated. 50 mT magnetic field could accelerate complete granulation time from 45 d (0 mT) to 30 d (50 mT) by promoting the settling ability of AGS and stimulating the secretion of extracellular polymeric substances (EPS). With 50 mT magnetic field, partial nitrification-denitrification in AGS was enhanced, and the removal efficiency of chemical oxygen demand (COD), NH4+-N and TN increased by 7.6%, 26.2% and 41.5% comparing with the control (0 mT). Magnetic field balanced the dominant genera Thauera, Flavobacterium, Chryseobacterium and Meganema, which further enhanced the aerobic granulation and partial nitrification-denitrification in AGS. Thus, the application of magnetic field is reliable for accelerating aerobic granulation and enhancing partial nitrification-denitrification process.
Thi Hai NguyenSeongchul RyuParipurnanda Loganathan
8页
查看更多>>摘要：Arsenic (As) contamination of drinking water supplies is a major concern in many countries due to its large concentration in groundwater and high toxicity. In this study, batch adsorption experiments on a natural laterite adsorbent from Vietnam (NLTT) were firstly conducted, followed by four column adsorption experiments using NLTT working with synthetic water under different experimental conditions (initial arsenate As(V) concentration: 0.1 and 0.5 mg/L; bed height: 0.15 and 0.41 m). Results from the batch equilibrium adsorption study show that all three models-Sips, Langmuir, and Freundlich-fitted the experimental data very well. The Sips and Langmuir maximum adsorption capacities were 0.76 mg/g and 0.58 mg/g, respectively. At an As(V) concentration of 0.5 mg/L, adsorption breakthrough occurred at 28 h and 122 h for column heights of 0.15 m and 0.41 m, respectively. When As(V) concentration fell to 0.1 mg/L, the breakthrough times rose to 144 h and 240 h, respectively. A linear driving force approximation (LDFA) model incorporating the Sips equation was calibrated with data from the equilibrium and kinetic adsorption experiments and one column adsorption experiment (initial concentration: 0.1 mg/L; bed height: 0.15 m). The LDFA model with the calibrated model coefficients could predict the breakthrough curves and adsorption time in the three other column experiments and four household column filters used to treat As contaminated groundwater in Vietnam. The study revealed that application potential for NLTT in column adsorption studies and field trials to remove As(V) is significant despite this study having limited data. Subsequently, refining the model based on simulation of results is cost-effective, saves time and effort, and negates the need for multiple experiments to optimize filter conditions.
查看更多>>摘要：The role of Nb doping in improving anti-K poisoning ability of CeO2-TiO2 catalyst was investigated by SCR activity evaluation, BET, XRD, XPS, NH3-TPD, H2-TPR and in situ DRIFTS. The catalytic activity of the Nb-modified CeO2-TiO2 catalyst was vastly superior to that of the CeO2-TiO2 catalyst in the presence of K. The doping of Nb could enhance the BET surface area and alleviate the surface crystallinity of the CeO2-TiO2 catalyst both before and after the introduction of K. In addition, the smaller decrease in the ratio of Ce3+/ Ce~(4+), surface chemisorbed oxygen, Bransted acidity and redox property was observed on the Nb-modified CeO2-TiO2 catalyst in the presence of K. The results of in situ DRIFTS indicated that all of the reactions were controlled by combined E-R and L-H mechanisms on the fresh and K-poisoned catalysts. The addition of Nb could enhance the adsorption of NO and NH3, but not all NOx adsorbed species were reactive in the NH3-SCR reaction for K-poisoned CeO2-TiO2. All the above factors contributed to enhance its K-poisoning resistance of CeO2-TiO2 due to the doping of Nb.
查看更多>>摘要：Top of the line corrosion (TLC) is one of the main root causes for many multiphase pipeline failures in the upstream oil and gas industry. The most challenging issue for assessment of TLC in multiphase pipelines is simulating the operational conditions to find out the governing mechanisms of corrosion and its inhibition. The current work aimed to develop a novel setup for evaluating the TLC and its inhibition using the in-situ electrochemical techniques under simulated conditions. Moreover, since one of the major influencing factors in TLC is the pressure of acid gases (CO2 and H2S), an autoclave was designed to provide the feasibility of in-situ electrochemical experiments under pressurized conditions. Specialized probes were developed and placed at both the top and bottom of the autoclave to study and compare the corrosion behavior and inhibition performance at both locations. To check the function of the setup, different experiments, including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization scanning (PDS), and linear polarization resistance (LPR) were conducted in different conditions. The performance of the system was validated by comparing the electrochemical results with weight loss coupons in autoclave and a field study in actual conditions The capability of the setup for evaluating the smart inhibition of TLC was checked with an amine-based volatile corrosion inhibitor and confirmed by EIS.
查看更多>>摘要：Coal fly aerogel (CFAA), as a low-cost, recyclable and highly efficient U(VI) adsorbent, was successfully prepared. Notably, the removal rate for U(VI) of CFAA was up to 94.5% (C0 = 10 mg L-1, m/V = 1.0 g L~(-1), T = 298 K, t = 24 h and pH = 3.0), which was much higher than previous studies. Meanwhile, the maximum removal capacity of U(VI) on CFAA was 110.73 mg g~(-1) (m/V = 1.0 g IT1, T = 298 K, t = 24 h and pH = 3.0), which was nearly twice as much as untreated coal fly ash. Notable, the removal rate of U(VI) by CFAA was more than 80% after five cycles, indicating that CFAA was a recyclable adsorbent. In addition, Pseudo-second-order and Langmuir model were more suitable to describe the adsorption behavior on the surface of CFAA, meaning that the rate limiting step might be chemical sorption or chemisorption involving valency forces through sharing or exchange of electrons between sorbent and sorbate. The conclusions of SEM, FT-IR, XRD as well as XPS further illustrated that adsorption behavior for U(VI) of CFAA was mainly depended on the groups on the surface of CFAA, such as OH", SiO and A1O". In conclusion, CFAA could be considered as an excellent candidate for the capture of U(VI) from wastewater.
查看更多>>摘要：Printed circuit boards (PCBs) is a major constituent of the waste electric and electronic equipment, which represents a rapidly growing disposal problem worldwide. In order to achieve large-scale treatment of PCB, this work designed an innovative pilot-scale fixed-bed pyrolysis experiment system and proposed detailed on-site temperature measurements to quantify the impact and the delays of the temperature acceleration process. The large heat absorption of the pyrolysis reaction causes low heat transfer efficiency and significant temperature gradient along the vertical of the polit-scale furnance. Furthermore, X-ray fluorescence spectrometer, scanning electron microscope, gas chromatography-mass spectrometer and ion chromato-graph were applied for the analysis of the pyrolysis product characteristics. The proportions of the phenolic compounds are 69.23%, 68.46% and 56.17% corresponding to the temperatures of 350 °C, 450 °C, and 550 "C, respectively. Moreover, the organic bromine in the pyrolysis oil was suppressed by increasing the temperature to 550 °C. The respective contents are 46.02 mg/g, 44.19 mg/g and 38.96 mg/g. The results from this study are useful to provide necessary knowledge for the design and optimisation of the industrial application of PCB pyrolysis devices.
查看更多>>摘要：The continuous rise in crude oil prices over the last decades and crisis in feedstock availability together with food-versus-fuel debate has directed the utilization of industrial wastes for biodiesel production. Accordingly, the biodiesel or fatty acid methyl ester production has been largely explored and demonstrated with a wide variety of wastes (as feedstock materials) of which the dairy waste scum from dairy industries has been recently shown to be a viable and promising feedstock. Therefore, a critical overview on the salient features, and desirable advancements achieved with regard to dairy waste scum derived biodiesel production has become crucial. In this context, this review gives insights into the dairy scum oil methyl ester (DSOME) production, its engine feasibility and economic viability. With the scientific progress made so far by many researchers, this study compiles and analyzes numerous homogeneous, heterogeneous, nano, and bio catalysts that can be adopted for DSOME production. The feasibility of DSOME usage in engine with and without modification has also been critically discussed. An economic analysis has also been carried out to demonstrate the small-scale production of DSOME to signify its economic viability. Thus, with the possibility of demand for biodiesel, and towards addressing the feedstock crisis, the dairy scum can be potentially developed as viable feedstock as it is abundantly and continuously available waste-material in dairy industries. This also contributes to the effective management of dairy wastes. Finally, a list of suggestions to fill the research and development gap in production, engine feasibility and economic analysis has also been proposed.
查看更多>>摘要：The ammonia slip from denitration system can result in environmental damage. Selective catalytic oxidation of ammonia (NH3-SCO) to nitrogen is one of the ideal technologies to control NH3 emission. In this work, RuO2/RuO2/Sn_(0.2)Ti_(0.8)O2 catalysts with different Ru content and modified with Sb or Nb were evaluated for NH3-SCO. The results indicated that the RuO2&Nb2O5/RuO2/Sn_(0.2)Ti_(0.8)O2 exhibited the similar catalytic activity and superior N2 selectivity within a wide temperature range in NH3-SCO, in comparison with RuO2/RuO2/Sn_(0.2)Ti_(0.8)O2 and RuO2&Sb2O5/RuO2/Sn_(0.2)Ti_(0.8)O2. Multiple techniques were used to reveal the effect of the physicochemical properties of the catalysts on the catalytic activity and N2 selectivity. For RuO2/RuO2/Sn_(0.2)Ti_(0.8)O2, with the increasing ruthenium loading the activity enhanced together with the decline in N2 selectivity due to the high redox ability of highly dispersed ruthenium and the lack of acid sites. Particularly, in situ DRIFTS and NH3-TPD demonstrated the addition of Nb2O5 increased the quantity of acid sites, especially the Bransted acid sites that were essential to improve N2 selectivity. During NH3 oxidation, the Bransted acid sites promoted the activation of adsorbed ammonia to produce abundant amide intermediates (-NH2), which could directly react with the NO species to generate N2.
查看更多>>摘要：Contamination of paddy soils with arsenic (As) poses imminent threat to the environment and public health. This research work explored the effect of goethite-modified biochar (GMBC) on As immobilization in paddy soil and subsequent accumulation in rice grains. The results showed that the soil supplementation with GMBC significantly improved the biomass of rice plants. In addition, the GMBC application effectively decreased the As content in rice grains (0.72-0.16 mg kg~(-1)). Compared with the control, GMBC 1.5% treatment augmented the iron plaque (Fe-plaque) buildup on rice roots and efficiently sequestered the As by 174%, and reduced its uptake in rice tissues. Soil supplementation with GMBC 1.5% greatly enhanced the activities of soil peroxidase (POD) and catalase (CAT) by 90% and 40%, respectively, compared to the control. Moreover, GMBC amendments improved the relative abundance of the soil bacterial communities and minimized the As mobility in the soil. GMBC 1.5% significantly enhanced the abundance of acidobacteria and Firmicutes by 211% and 95% while that of Chloroflexi decreased by 25%, respectively. The findings of the present investigation demonstrated that GMBC could be used as an environment-friendly approach to remediate As polluted paddy soils and minimize its accumulation in rice grains for mitigation of food security risks and protect public health.
查看更多>>摘要：Natural gas leakage can impose significant danger on a facility and its surrounding communities. Methods for early detection and diagnosis of such leakages have been developed and widely used for gas pipelines and storage tanks. Most techniques include inspection of sensor-aided mathematical models. Application of machine learning techniques to gas leakage detection has been rarely explored. In the present work, con-volutional network (to model spatial likelihood of leak) is combined with bi-directional long short-term memory layer network, or BiLSTM (to model temporal dependence of leak likelihood) to perform leak detection and diagnosis. The developed model was trained and tested using sequence of concentration profiles generated using open-source simulated data. The model learned successfully to predict gas leakage and classify its size. The study also explores the flexibility of this network to perform quick detection and diagnose with the limited data. While the networks did not require parameter adjustments to achieve high prediction accuracy, further optimization is possible through data selection and pre-processing. The model needs to be further tested for wide range of leak scenarios. At its present condition, the combined application of convolutional network and BiLSTM shows promising results for early and accurate leak detection in natural gas facilities. Experimental results are needed to confirm the effectiveness of the model and data uncertainty.
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