A novel modified nanoporous bismuth electrode (modified-NPBiE) sensor was prepared by consecutive procedures which consist of bismuth (Bi) and tin (Sn) electroplating, thermal treatment for alloying ...Bi-Sn film, and selective chemical dealloying of Sn. The newly prepared modified-NPBiE sensor exhibited improved lifetime (2.7 times longer than a conventional nanoporous Bi-filmed electrode with over 40 repeated measurements) sensor with lower relative standard deviation (RSD), indicating enhanced stability and reproducibility for heavy metal detection. Using square wave anodic stripping voltammetry (SWASV), two noticeable peaks were observed at −0.65 V and −0.45 V associated with stripping currents of Cd2+ and Pb2+ in 0.1 M acetate buffer solution at pH 4.6, respectively. The calibration curves showed strong correlations with respect to various concentrations of Cd2+ and Pb2+ with the limit of detection (LOD) of 1.3 ppb for Cd2+ and 1.5 ppb for Pb2+. The newly modified-NPBiE sensor was then successfully applied for detecting Cd2+ and Pb2+ in a tap water environment and exhibited an acceptable performance for measuring heavy metals with a good reliability.
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•A modified-NPBiE sensor was developed by a separate Bi-Sn electroplating process.•Nanoporous Bi structure after selective Sn etching improved sensor stability.•The modified-NPBiE sensor showed good reproducibility over 40 times of measurements.•The modified-NPBiE sensor successfully measured Cd2+ and Pb2+ in a tap water.
•Sequential leaching and wet torrefaction were carried out to improve the fuel properties.•Ash content in EFB was removed effectively by the leaching process.•Most potassium and chloride were removed ...by leaching and wet torrefaction.•The hydrophobicity of the biomass was enhanced by sequential leaching and wet torrefaction.
In this study, sequential leaching (60 °C, 5 min) and wet torrefaction (200 °C, 5 min) of biomass were carried out to improve the fuel properties of waste biomass, made up of empty fruit bunches (EFB), rice straws (RS), or sugarcane bagasses (SB). Most of the hemicellulose was removed during wet torrefaction. The ash removal efficiency by sequential leaching and wet torrefaction differed depending on the biomass. After leaching and wet torrefaction, the ash removal efficiency of the EFB was the highest (67.99%). Most of the potassium and chloride in the biomass were removed. In particular, the removal efficiencies for the EFB were the highest (98.62% and 99.27%, respectively). The heating values increased by 4.42% in the EFB, 4.68% in the RS, and 5.30% in the SB. Pellet production was successfully carried out with the leaching and wet-torrefied biomass (EFB). The hydrophobicity of the pellets was considerably higher than that of the raw material.
Water quality control and management in water resources are important for providing clean and safe water to the public. Due to their large area, collection, analysis, and management of a large amount ...of water quality data are essential. Water quality data are collected mainly by manual field sampling, and recently real-time sensor monitoring has been increasingly applied for efficient data collection. However, real-time sensor monitoring still relies on only a few parameters, such as water level, velocity, temperature, conductivity, dissolved oxygen (DO), and pH. Although advanced sensing technologies, such as hyperspectral images (HSI), have been used for the areal monitoring of algal bloom, other water quality sensors for organic compounds, phosphorus (P), and nitrogen (N) still need to be further developed and improved for field applications. The utilization of information and communications technology (ICT) with sensor technology shows great potential for the monitoring, transmission, and management of field water-quality data and thus for developing effective water quality management. This paper presents a review of the recent advances in ICT and field applicable sensor technology for monitoring water quality, mainly focusing on water resources, such as rivers and lakes, and discusses the challenges and future directions.
A novel bismuth (Bi)-biopolymer (chitosan) nanocomposite screen-printed carbon electrode was developed using a Bi and chitosan co-electrodepositing technique for detecting multiple heavy metal ions. ...The developed sensor was fabricated with environmentally benign materials and processes. In real wastewater, heavy metal detection was evaluated by the developed sensor using square wave anodic stripping voltammetry (SWASV). The nanocomposite sensor showed the detection limit of 0.1 ppb Zn
, 0.1 ppb Cd
and 0.2 ppb Pb
in stock solutions. The improved sensitivity of the Bi-chitosan nanocomposite sensor over previously reported Bi nanocomposite sensors was attributed to the role of chitosan. When used for real wastewater samples collected from a mining site and soil leachate, similar detection limit values with 0.4 ppb Cd
and 0.3 ppb Pb
were obtained with relative standard deviations (RSD) ranging from 1.3% to 5.6% (
= 8). Temperature changes (4 and 23 °C) showed no significant impact on sensor performance. Although Zn
in stock solutions was well measured by the sensor, the interference observed while detecting Zn
in the presence of Cu
was possibly due to the presence of Cu-Zn intermetallic species in mining wastewater. Overall, the developed sensor has the capability of monitoring multiple heavy metals in contaminated water samples without the need for complicated sample preparation or transportation of samples to a laboratory.
•Salt concentration had more of an effect than salt type on algal metabolisms.•Salinity stress reduced the growth of Chlorella vulgaris.•Salinity stress increased total lipid content and saturated ...portions of fatty acids.•Algae settling was improved by 33–83% with increased NaCl concentrations.
Microalgae can offer several benefits for wastewater treatment with their ability to produce large amounts of lipids for biofuel production and the high economic value of harvested biomass for biogas and fertilizer. This study found that salt concentration (∼45gL−1) had more of an effect than salt type on metabolisms of Chlorella vulgaris for wastewater treatment and biofuel production. Salinity stress decreased the algal growth rate in wastewater by 0.003day−1permScm−1 and slightly reduced nutrient removal rates. However, salinity stress was shown to increase total lipid content from 11.5% to 16.1% while also increasing the saturated portions of fatty acids in C. vulgaris. In addition, salinity increased the algal settling rate from 0.06 to 0.11mday−1 which could potentially reduce the cost of harvesting for algal biofuel production. Overall, C. vulgaris makes a suitable candidate for high salinity wastewater cultivation and biofuel production.
•There is a lack of information on the use of ultrasonication at large scales/the field.•The efficiency of ultrasonication for algal removal in field is still debatable.•Attenuation of ultrasonic ...intensity needs to be considered in field applications.•Further field data is required for the upscaling of ultrasonication devices.
Algal blooms are a naturally occurring phenomenon which can occur in both freshwater and saltwater. However, due to excess nutrient loading in water bodies (e.g. agricultural runoff and industrial activities), harmful algal blooms (HABs) have become an increasing issue globally, and can even cause health effects in humans due to the release of cyanotoxins. Among currently available treatment methods, sonication has received increasing attention for algal control because of its low impact on ecosystems and the environment. The effects of ultrasound on algal cells are well understood and operating parameter such as frequency, intensity, and duration of exposure has been well studied. However, most studies have been limited to laboratory data interpretation due to complicated environmental conditions in the field. Only a few field and pilot tests in small reservoirs were reported and the applicability of ultrasound for HABs prevention and control is still under question. There is a lack of information on the upscaling of ultrasonication devices for HAB control on larger water bodies, considering field influencing factors such as rainfall, light intensity/duration, temperature, water flow, nutrients loading, and turbidity. In this review article, we address the challenges and field considerations of ultrasonic applications for controlling algal blooms. An extensive literature survey, from the fundamentals of ultrasound techniques to recent ultrasound laboratory and field studies, has been thoroughly conducted and summarized to identify future technical expectations for field applications. Case studies investigating spatial distribution of frequency and pressure during sonication are highlighted with future implications.
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•A Fe-Chitosan-coated sensor was developed for in situ As(III) detection.•The sensor was successfully applied for mining wastewater and soil leachate.•The sensor displayed good ...selectivity and reproducibility in real wastewater.•The interference from metal ions was found negligible for As(III) detection.
A novel As(III) sensor was developed by co-electrodepositing a Fe-Chitosan composite to a screen-printed carbon electrode sensor. The newly developed Fe-Chitosan-coated carbon electrode sensor exhibited successful As(III) detection in mining wastewater and soil leachate using square wave anodic stripping voltammetry (SWASV). A noticeable peak was observed at +0.15 V associated with stripping current of As(III) for both real wastewater samples. The calibration curves showed strong correlations with respect to As(III) with the limit of detection (LOD) of 1.12 ppb for mining wastewater and 1.01 ppb for soil leachate, respectively. Lower relative standard deviations (RSD) were obtained with 2.91% for mining wastewater and 4.54% for soil leachate during repeated measurements (n = 8), respectively, indicating enhanced stability for As(III) detection in the real wastewater application. The interference from copper and other metal ions (e.g., Zn(II), Pb(II) and Cd(II)) was found negligible for As(III) detection using the polymer modified Fe-coated electrode sensor, which suggests that the Fe-chitosan composite imparted the selectivity in the presence of other metal ions to As(III) detection in complex water matrix. These results demonstrate the applicability of a novel Fe-Chitosan-coated carbon electrode sensor to real wastewater As(III) pollution monitoring with the acceptable range of characteristics.
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•SDS addition to bilge water significantly improved MFC performance.•NaCl over 50 mM affected negatively MFC performance.•Triton X-100 showed bacterial growth inhibition growth and ...poor electroactivity.•Bilge water is a promising substrate for power generation by MFCs.
Effective remediation of bilge water, a shipboard oily liquid waste, is important for both commercial and military vessels due to the domestic and international regulations. In this study, bilge water was used as a substrate for exoelectrogenic bacteria and biodegradation of bilge water and concurrent electricity generation were investigated using Pseudomonas putida ATCC 49128 in single chamber microbial fuel cells (MFCs). To enhance bioavailability of the bilge water, two types of surfactants were added (100 ppm) into the oily wastewater containing 0.1% standard bilge mix (SBM) and their impacts on electricity production were evaluated under various conditions. Anionic surfactant (sodium dodecyl sulfate, SDS) addition increased soluble chemical oxygen demand (SCOD) by forming micelle, producing maximum power density of 225.3 ± 3.2 mW m−2. However, the MFC with nonionic surfactant (Triton X-100) produced only 2.3 ± 0.1 mW m−2 due to no enhancement on biodegradable SCOD. A high NaCl concentration (100–500 mM) adversely affected power production due to decrease in available SCOD caused by emulsion coalescence. This is a first study to use surfactants to enhance bioavailability of non-biodegradable oily wastewater in a single chamber MFC.
Following curative liver resection (LR), resectable tumor recurrence in patients with preserved liver function leads to deciding between a repeat LR and a salvage liver transplantation (LT), if a ...donor’s liver is available. This retrospective study compared survival outcomes and recurrence pattern following salvage living donor LT (LDLT) and repeat LR in patients with recurrent hepatocellular carcinoma (HCC). We reviewed the medical records of patients who underwent repeat LR (n = 163) or LDLT (n = 84) for recurrent HCC following curative resections, between January 2005 and December 2017 at a single institution. A 1:1 propensity score matching led to 42 patients per group. Disease‐specific and recurrence‐free survival were significantly better in the salvage LDLT group than in the repeat LR group (p = .042; HR = 2.40; 95% CI, 0.69–6.00 and p < .001; HR = 4.23; 95% CI, 2.05–8.71, respectively). Despite significant differences in recurrence patterns between the two groups (p = .019), the patient death rates, after recurrence, were similar for both groups (p = .760). This study indicates that salvage LDLT is superior to repeat LR for treating patients with transplantable, intrahepatic HCC recurrence, even in patients with Child‐Pugh class A liver cirrhosis.
Salvage living donor liver transplantation is superior to repeat liver resection to treat patients with transplantable, recurrent intrahepatic hepatocellular carcinoma, even in patients with Child–Pugh class A liver cirrhosis.
Understanding the effect of various environmental factors on algal blooms is essential for proper management of water resources. Eight weirs were constructed on the Nakdong River in South Korea ...between 2010 and 2011 to manage water resources and deal with possible floods and droughts. In this study, water quality observation data were collected from eight representative monitoring sites in the Nakdong River between 2001 and 2016. Particularly, the effect of the weirs construction on water retention time was statistically analyzed in terms of algal growth and other important water quality parameters. While there was slight increase of water temperature (0.8 °C) over 16 years, the concentrations of total phosphorous (TP) and total nitrogen (TN) decreased by 62.3, and 12.9%, respectively, after the construction of weirs. This TP decrease was noticeable, but still high enough to maintain the eutrophic state of the river. Correlation statistical analysis suggests that the Chl-
a
concentration is positively affected by the changes of TP, TN and chemical oxygen demand. However, there was no direct correlation between Chl-
a
concentration and the increased water retention time from the weir construction.
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