Mass balance analysis on the behavior of major elements disposed at a waste landfill site.

Understanding the behavior of major elements in landfill is necessary for effective landfill site management. However, there have been no established methods to study the mass balance of major landfill elements, excluding some studies focused on specific target materials. In this study, different landfill management methodologies were used to conduct mass balance analysis of three major elements at Sudokwon Landfill Site 2 (LS2) in South Korea during 2001-2014. The results indicated that biochemically decomposable carbon accounted for 38.2% of the total landfill organic carbon content. Further, 51.3% of this decomposable fraction underwent decomposition during the research period, 99.0% of which was emitted in landfill gas as CO2 and CH4. In terms of sulfur, 6.1% of the total decomposed sulfur was emitted as H2S (97.0%), and almost all of the total decomposed nitrogen was emitted (5.7%) in leachate as NH4+-N. LS2 had a low decomposition rate due to the dryness of the landfill site and the increasing ratio of demolition waste, which does not decompose easily. Therefore, thermochemical energy recovery before waste disposal and leachate recycling seem to be necessary. In terms of leachate recycling, economic measures to prevent nitrogen accumulation may be required in the long term. Additionally, for suppressing H2S generation, separate disposal of waste soil produced throughout the course of mechanical pretreatment of demolition waste should be conducted.

Detection of trace metal in distilled alcoholic drinks.

The presence of trace metal cadmium assay was investigated with a copper immobilized on a graphite carbon electrode (GPC), the modified property of which was determined with handheld voltammetric systems. Following the determination of the analytical stripping conditions of 0.45 V amplitude, 30 Hz frequency, -1.4 V initial potential, and 4.0 mV increment potential, only a 60-s experimental accumulation time was used. Using these conditions, the analytical detection limit approached the nano range. At this condition, the analytical application was performed on distilled alcoholic drinks for food manufacturing systems. This developed technique is faster and less costly than the common voltammetric and spectrophotometric methods.

Diagnostic Assay of Trace Mercury in Muscle Cells.

An electrochemical diagnostic assay of a trace mercury was performed using stripping voltammetry, cyclic voltammetry and chronoamperometry. Three graphite pencil electrode systems were used as the working, auxiliary and reference electrodes. Fluorine immobilization was performed on the working electrode to improve the sensitive low detection limit. Clean seawater was used instead of an expensive electrolyte such as buffer solution, acid or base solution. The working ranges are better sensitive then observed for analogous method. The result was applied to the muscle cell of an earthworm that lived in soil contaminated with trace mercury.

Detection of Helicobacter pylori DNA in preliminary stage gastric cancer cells.

AIMS: Helicobacter pylori (HP) DNA was assayed using a newly fabricated voltammetric handheld circuit equipped with an interfaced graphite pencil electrode (PE) sensor. METHODS: Under optimum analytical parameters, the square-wave (SW) stripping detection range attained was 0.1-0.7 mg/L. RESULTS: A relative standard deviation of 1.68% (RSD, n = 5) was observed at a 3.2 mg/L HP DNA within a 90 s accumulation time. Under these conditions, the analytical detection limit approached 0.07 mg/L. CONCLUSIONS: The developed methods can be applied to HP assays of preliminary stage gastric cancer patient tissues.