活性炭涂层电极电容去离子的性能

采用活性炭涂层电极构建电容去离子吸附装置,以氯化钠模拟含盐原水,研究电压、流量、进水浓度等操作参数对活性炭涂层电极脱盐效率和能耗的影响。实验结果表明,去除率和比吸附量随着电压的增大而增加,且比能耗随之增大。流速越小,出水的浓度越低,当对出水的浓度要求较高时,宜采用小流速。当进水浓度低于活性炭涂层电极的饱和吸附量时,比吸附量随着进水浓度呈线性增加;当达到饱和吸附量时,比吸附量不会随进水浓度的增大而发生改变;比能耗随着进水浓度的增加而降低。     

A comparison of refrigerant management policies and suggestions for improvement in South Korea

HFCs (hydrofluorocarbons) emerged as alternative refrigerants after the production of chlorofluorocarbons was banned and hydrochlorofluorocarbons were phased out, under the Montreal Protocol on Substances that Deplete the Ozone Layer. However, because the Kyoto Protocol considered HFCs as greenhouse gases, and their impact on climate change has been increasing, major developed countries have been strengthening existing regulations on the use of HFCs as refrigerants. South Korea has also passed various legislations related to refrigerant management. However, reports indicate that implementation of these regulations has been ineffective, due to the absence of a specific system for managing the production, use, and disposal phases of refrigerants. To identify and resolve these issues, this study investigates the current state of refrigerant management in South Korea for those three phases. Refrigerant management policies are compared between different legislatures, using the examples of the European Union, United States, and Japan. Based on the findings, five types of measures are suggested to reduce the production and consumption of refrigerants, and to improve refrigerant management regulations in ways that are most appropriate to the South Korean context.     

A comparison study on high-temperature water–gas shift reaction over Fe/Al/Cu and Fe/Al/Ni catalysts using simulated waste-derived synthesis gas

A comparative study on Fe/Al, Fe/Al/Cu, and Fe/Al/Ni catalysts in high-temperature water–gas shift reaction (HT–WGS) using simulated waste-derived synthesis gas has been carried out. The metal oxide (Cu and Ni) and aluminum incorporated Fe catalysts were designed to get highly active HT–WGS catalysts. Despite the high CO concentration in the simulated waste-derived synthesis gas, Fe/Al/Cu catalyst exhibited the highest CO conversion (84 %) and 100 % selectivity to CO₂ at a very high gas hourly space velocity (GHSV) of 40,057 h^?1. The outstanding catalytic performance is mainly due to easier reducibility, the synergy effect of Cu and Al, and the stability of the magnetite.     

Combination of ion exchange system and biological reactors for simultaneous removal of ammonia and organics

A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH₄⁺ could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m²?s of a maximum flux. On the other hand, the removal of NO₃⁻ was 3.5 times faster than NH₄⁺ and the maximum flux was calculated to be 3.4 mg N/m²?s. The systems for NH₄⁺ and NO₃⁻ removal were combined for establishing the IEBR process. When the process was operated in a continuous mode, approximately 95.8% of NH₄⁺ was removed showing an average flux of 0.22 mg N/m²·s. The removal efficiency of total nitrogen was calculated as 94.5% whereas that of organics was 99.5%. It was concluded that the IEBR process would be effectively used for a simultaneous removal of NH₄⁺ and organics.     

Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes

There is growing interest in the development of more cost-effective and retrofit technologies for the upgrade and expansion of existing wastewater treatment plants with extreme space constraints. A free-floating sponge media (BioCube) process, using a 24L lab scale reactor, was operated to study the nitrification profiles and microbial community. The COD removal efficiencies were maintained, at an average of 95%, with the mixed liquor suspended solids (MLSS) inside the BioCube sponge media maintained at 12,688mg/L. The nitrification removal efficiencies were between 92% and 100%, with an average value of 99%. From the results of microelectrode measurements, the ammonium ion concentration was found to rapidly decrease from the surface of the BioCube sponge media to a depth of 2mm due to chemical reactions carried out by ammonia oxidizing bacteria (AOB) species. Multi-fluorescence in situ hybridization (FISH) has been used to investigate the spatial distributions of various microbial activities within reactors. Microbial communities were targeted using different oligonucleotide probes specific to AOB and nitrite oxidizing bacteria (NOB). There were a large number of AOB populations, but these were not uniformly distributed in the biofilm compared to the NOB populations.     

Biocatalyst physiology and interplay: a protagonist of MFC operation

Environmental Science and Pollution Research - Microbial fuel cells (MFC) have been foreseen as a sustainable renewable energy resource to meet future energy demand. In the past, several studies...     

Accumulation of butyl- and phenyltin compounds in starfish and bivalves from the coastal environment of Korea

Triphenyltin (TPT) and tributyltin (TBT) concentrations were determined in two starfish species (Asteria pectinifera and Asterias amurensis), bivalves (Crassostrea gigas or Mytilus edulis), and seawater samples from sites around the coasts of Korea. Both TPT and TBT concentrations in starfish ranged from 8 to 1560 ng/g and from <2 to 797 ng/g as Sn on a dry weight basis, respectively. TPT concentration accounted for 75.4% and 86.4% of total phenyltin concentration in A. pectinifera and A. amurensis, respectively, while monobutyltin, a degradation product of TBT, accounted for 86.3% and 57.2% of total butyltin, respectively. Triphenyltin concentrations in A. pectinifera were significantly correlated to water and bivalve TPT concentrations, which implies that dietary uptake of TPT from contaminated prey as well as direct uptake from surrounding water contribute to TPT body residues in the starfish. Starfish could be target organisms for monitoring TPT compound in the marine environment, due to their high accumulation and low degradation capacity towards TPT.     

Characteristics of carbonized sludge for co-combustion in pulverized coal power plants

Co-combustion of sewage sludge can destabilize its combustion profile due to high volatility, which results in unstable flame. We carried out fuel reforming for sewage sludge by way of carbonization at pyrolysis temperature of 300-500 °C. Fuel characteristics of carbonized sludge at each temperature were analyzed. As carbonization temperature increased, fuel ratio increased, volatile content reduced, and atomic ratio relation of H/C and O/C was similar to that of lignite. The analysis result of FT-IR showed the decrease of aliphatic C-H bond and O-C bond in carbonization. In the analysis result of TG-DTG, the thermogravimetry reduction temperature of carbonized sludge (CS400) was proven to be higher than that of dried sludge, but lower than that of sub-bituminous coal. Hardgrove grindability index increased in proportion to fuel ratio increase, where the carbonized sludge value of 43-110 was similar or higher than the coal value of 49-63. As for ash deposits, slagging and fouling index were higher than that of coal. When carbonized sludge (CS400) and coal were co-combusted in 1-10% according to calorific value, slagging tendency was low in all conditions, and fouling tendency was medium or high according to the compositions of coal.