Removal of Hydrogen Sulfide in Septic Tanks for Treating Black Water via an Immobilized Media of Sulfur-Oxidizing Bacteria.

In South Korea, the installation of septic tanks for treating black water (STBW) is regulated even in sewage treatment areas to prevent the black water deposition in combined sewers. STBWs in which black water is anaerobically decomposed generate high concentrations of hydrogen sulfide (H2S). In this study, an immobilized media of sulfur-oxidizing bacteria (SOB) was used to remove the H2S. SOB media was prepared by using activated sludge collected from a wastewater treatment plant. Prior to field application, an appropriate cultivation period and aeration rate for SOB activation were estimated through a laboratory-scale test. The SOB was activated after a 23-day cultivation period and an aeration rate of 0.25 L-water/L-air/min. Moreover, the maximum H2S removal efficiency was observed at a cultivation period of 43 days and an aeration rate of 0.38 L-water/L-air/min. Then, the SOB media was installed on STBWs of various capacities. The H2S removal efficiency was compared between with and without SOB media. The maximum H2S elimination capacity with SOB media was 12.3 g/m3/h, which was approximately three times higher than without SOB media. Furthermore, the energy efficiency and oxidation rate were also three times higher with SOB, demonstrating the applicability of SOB for H2S removal in STBW.

Operating cost reduction of UF membrane filtration process for drinking water treatment attributed to chemical cleaning optimization.

This study investigated the cost and CO2 emission reduced as a result of optimizing operating conditions for chemical cleaning in a membrane filtration process used for water treatment. A new protocol was proposed and operating conditions for chemical cleaning of a pilot-scale membrane filtration process were optimized. The critical flux for irreversibility was identified as the permeate flux using a modified flux-step method, and was 100 l m-2 h-1, 20 l m-2 h-1 higher than the vendor recommended permeate flux. NaOCl, which is also the vendor recommended chemical, was selected as the optimal chemical reagent following an examination of the permeability restoration ratios and nature of the irreversible foulants. The optimized operating conditions of enhanced flux maintenance (EFM), determined using response surface methodology (RSM) were: 6.3 d interval, 500 ppm concentration, and 76 min duration, which represented an increase of 4.3 d, 300 ppm, and 36 min, respectively, as opposed to the vendor recommended conditions. As a result, the total operating cost and CO2 emission were $0.1187/m3 and 112.75 g CO2/m3, respectively, and 26.5% lesser compared to the operating cost and CO2 emission based on vendor recommended conditions. This study found that the reductions in operating cost and CO2 emission using the optimization process were excellent.

Evaluation of Removal Mechanisms in a Graphene Oxide-Coated Ceramic Ultrafiltration Membrane for Retention of Natural Organic Matter, Pharmaceuticals, and Inorganic Salts.

Functionalized graphene oxide (GO), derived from pure graphite via the modified Hummer method, was used to modify commercially available ceramic ultrafiltration membranes using the vacuum method. The modified ceramic membrane functionalized with GO (ceramicGO) was characterized using a variety of analysis techniques and exhibited higher hydrophilicity and increased negative charge compared with the pristine ceramic membrane. Although the pure water permeability of the ceramicGO membrane (14.4-58.6 L/m2 h/bar) was slightly lower than that of the pristine membrane (25.1-62.7 L/m2 h/bar), the removal efficiencies associated with hydrophobic attraction and charge effects were improved significantly after GO coating. Additionally, solute transport in the GO nanosheets of the ceramicGO membrane played a vital role in the retention of target compounds: natural organic matter (NOM; humic acid and tannic acid), pharmaceuticals (ibuprofen and sulfamethoxazole), and inorganic salts (NaCl, Na2SO4, CaCl2, and CaSO4). While the retention efficiencies of NOM, pharmaceuticals, and inorganic salts in the pristine membrane were 74.6%, 15.3%, and 2.9%, respectively, these increased to 93.5%, 51.0%, and 31.4% for the ceramicGO membrane. Consequently, the improved removal mechanisms of the membrane modified with functionalized GO nanosheets can provide efficient retention for water treatment under suboptimal environmental conditions of pH and ionic strength.

Electrostatic-Force-Assisted Dispensing Printing to Construct High-Aspect-Ratio of 0.79 Electrodes on a Textured Surface with Improved Adhesion and Contact Resistivity.

As a novel route to construct fine and abnormally high-aspect-ratio electrodes with excellent adhesion and reduced contact resistivity on a textured surface, an electrostatic-force-assisted dispensing printing technique is reported and compared with conventional dispensing and electrohydrodynamic jet printing techniques. The electrostatic force applied between a silver paste and the textured surface of a crystalline silicon solar cell wafer significantly improves the physical adhesion of the electrodes, whereas those fabricated using a conventional dispensing printing technique peel off with a silver paste containing 2 wt% of a fluorosurfactant. Moreover, the contact resistivity and dimensionless deviation of total resistance are significantly reduced from 2.19 ± 1.53 mΩ · cm(2) to 0.98 ± 0.92 mΩ · cm(2) and from 0.10 to 0.03, respectively. By utilizing electrodes with an abnormally high-aspect-ratio of 0.79 (the measured thickness and width are 30.4 µm and 38.3 µm, respectively), the cell efficiency is 17.2% on a polycrystalline silicon solar cell with an emitter sheet resistance of 60 Ω/sq. This cell efficiency is considerably higher than previously reported values obtained using a conventional electrohydrodynamic jet printing technique, by +0.48-3.5%p.

Percutaneous Cholangioscopic Lithotripsy for Afferent Loop Syndrome Caused by Enterolith Development after Roux-en-Y Hepaticojejunostomy: A Case Report.

Afferent loop obstruction caused by enterolith formation is rare and cannot be easily treated with endoscopy because of the difficulty associated with the nonsurgical removal of enteroliths. A 74-year-old woman was admitted with fever and acute abdominal pain. Clinical features and imaging studies suggested afferent loop obstruction caused by an enterolith after Roux-en-Y hepaticojejunostomy. Percutaneous transhepatic biliary drainage was initially performed because of severe cholangitis with septic shock. The enterolith was located in the jejunal limb adjacent to the hepaticojejunostomy site. Cholangioscopic lithotripsy was performed through the percutaneous transhepatic route to the enterolith, and the fragments were moved into the efferent loop using scope push and saline flush methods. Here, we describe a case of afferent loop syndrome caused by an enterolith that developed after Roux-en-Y hepaticojejunostomy and was treated with percutaneous transhepatic cholangio-enteroscopic lithotripsy.

A new NMR-based metabolomics approach for the diagnosis of biliary tract cancer.

BACKGROUND & AIMS: Biliary tract cancer is highly lethal at presentation, with increasing mortality worldwide. Current diagnostic measures employing multiple criteria such as imaging, cytology, and serum tumor markers are not satisfactory, and a new diagnostic tool is needed. Because bile is a cognate metabolite-rich bio-fluid in the biliary ductal system, we tested a new metabolomic approach to develop an effective diagnostic tool. METHODS: Biles were collected prospectively from patients with cancer (n=17) or benign biliary tract diseases (n=21) with percutaneous or endoscopic methods. Nuclear magnetic resonance spectra (NMR) of these biles were analyzed using orthogonal partial least square discriminant analysis (OPLS-DA). RESULTS: The metabolomic 2-D score plot showed good separation between cancer and benign groups. The contributing NMR signals were analyzed using a statistical TOCSY approach. The diagnostic performance assessed by leave-one-out analysis exhibited 88% sensitivity and 81% specificity, better than the conventional markers (CEA, CA19-9, and bile cytology). CONCLUSION: The NMR-based metabolomics approach provides good performance in discriminating cancer and benign biliary duct diseases. The excellent predictability of the method suggests that it can, at least, augment the currently available diagnostic approaches.

[A case of colon obstruction developed as a complication of acute pancreatitis].

In acute pancreatitis, colonic complications such as mechanical obstruction, ischemic necrosis, hemorrhage, and fistula are rare but their outcomes are fatal. It is known that colonic obstruction in acute pancreatitis is more likely found in splenic flexure and transverse colon caused by severe inflammation of body and tail of pancreas leading to pressure necrosis. A 43-year-old man presented with abdominal distension lasting for 2 weeks. The patient had been admitted to our institution 6 weeks prior to the current admission, and the abdominal CT scan performed during the first admission revealed the pancreatic enlargement with peri-pancreatic fatty infiltration and fluid collection. At that time he was diagnosed as acute pancreatitis. The conservative management resulted in clinical improvement so that the patient was discharged. Upon the second admission, abdominal CT scan revealed multiple pseudocysts in the tail portion of pancreas with concominant wall thickening and narrowing of the proximal descending colon, and a dilatation of the bowel proximal to the splenic flexure. An obstruction of the descending colon as a complication of acute pancreatitis was suspected and the patient underwent left hemicolectomy. Abdominal distension was relieved after the operation and he was discharged on the 15th hospital days.