• Journal of Korean Society of Environmental Engineers
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• v.36 no.9
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• pp.604-608
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• 2014

This study investigated influence of dissolved organic nitrogen (DON) in natural organic matter (NOM) on the formation of organic chloramines upon monochloramination. Ratios of dissolved organic carbon (DOC) to DON of the 16 NOM isolates ranged from 7 to 47 mg-C/mg-N. Levels of organic chloramines maxed in 24 hours at $0.16mg-Cl_2/mg-N$ in average. The yields were relatively lower, but decay of organic chloramines were slower than those upon chlorination. Organic chloramines formed upon monochloramination decreased by 56% in average in 120 h. NOM with lower DOC/DON ratios formed more organic chloramines. NOM fractions such as hydrophobic, hydrophilic, transphilic, and colloidal did not significantly impact formation of organic chloramines. As the monochloramine doses increased, more organic chloramines were produced ($R^2=0.91$). Overestimation of disinfection capacity due to the formation of organic chloramines may not be concerns for monochloramine systems since only 6% of monochloramine could be converted to organic chloramines upon monochloramination of NOM.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.535-540
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• 2005

This study was conducted to evaluate the chlorinated disinfection by-products formation potential (DBPFP) produced from the cell and extracellular product (ECP) of Chlamydomonas pulsatilla after chlorination. Reaction yields of DBPs produced by C. pulsatilla of ECP and the cell were $0.007{\mu}mol/mg{\cdot}C$ and $0.808{\mu}mol/mg{\cdot}C$ respectively, Also, SUVA values of ECP and the cell were measured as $0.313L/mg{\cdot}m$ and $1.052L/mg{\cdot}m$ respectively, The DOC of cell was found to be lower than that of ECP, while the SUVA value and reaction yields for the cell were higher than those of ECP. For ECP, most of the DBPFP was composed of trihalomethanes (THM; 47.3%) and haloacetonitriles (HAN; 38,83%). THM and HAN were the major DBPFP produced by the cell. Chloroform was found to be the major THM compound; 98.3% for ECP and 99.98% for the cell. Dichloroacetic acid (DCAA) and dichloroacetonitrile (DCAN) were identified as the major haloacetic acid (HAA) and HAN compounds formed by ECP and the cell as a precursor, respectively. As the chlorine dose was increased, concentrations of DOC, THMs, and HANs were increased. However, the chlorine dose decreased the concentration of chlorophyll-a.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.205-212
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• 2008

This study aimed to investigate the biofilm formation, bacterial regrowth, and bacterial community structure in the granular-activated carbon (GAC) filter adsorbers (FAs) used in water treatment plants. In 2005 and 2006, raw water, settled water, GAC FA by depth, and filtered water were collected twice a year from water treatment plants (WTPs) B and S. The number of heterotrophic bacteria, including mesophilic and psychrophilic bacteria, in such collected waters was investigated along with the total number of coliforms therein. Heterotrophic bacteria were detected in most samples, mainly at the surface layers of the GAC FAs, and fewer such bacteria were found in the lower and bottom layers. An increase in the bacterial number, however, was observed in the samples from various depths of the GAC FAs in WTPs B and S compared with the surface layers. An increase in the bacterial number was also detected in the filtered water. This may indicate that there is a regrowth of the bacteria in the GAC FA. Considering, however, that heterotrophic bacteria were not found in the filtered water, it can be deduced that most bacteria are removed in the chlorination process. Coliforms were detected at the surface layer of the GAC FAs, but their regrowth was not observed. MicroLog systems were used to identify the bacteria community distribution. Eight genera and 14 species, including Pseudomonas spp., were detected in WTP B, and 8 genera and 9 species, including Aeromonas spp., in WTP S. Further studies are required to elucidate their role in the biofilms in water treatment processes.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11a
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• pp.194-204
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• 1999

The use of genetically cloned xylanase acquired from Bacillus strearthermophillus improves bleachability for oak kraft pulps. Combination of xylanase(X). oxygen(O), ozone(Z). peroxide(P), alkaline extraction(Eo. Eop), and chlorination(C/D, D) have been tested in a variety of bleaching sequences. The effectiveness of xylanase pre-treatment(XO) and post-treatment(OX) in oxygen bleaching is mainly compared. With xylanase treatment the brightness increase by 1.5-2.1% ISO in OZEP, OZEoP, OZEopP and OPZP sequences. There is only numerically difference of brightness gains between OX and XO sequences. With xylanase treatment chemical requirements for bleaching decrease by 42.6-48.6% in OC/DEoD sequence and 47.9-54.7% as active chlorine in OC/DEopD sequence at the same brightness. the reduction of bleaching chemicals is higher in XO sequence than those in OX sequence. Following xylanase treatment the viscosity increases from 11.7-12.0 mPa·s to 12.4-13.5 mPa·s and the brightness stability is considerably improved however the difference of effectiveness between XO and OX sequence is not present. Compared to tensile index vs tear index, the physical properties are similar for TCF bleaching sequences with and without xylanase treatments. However in OC/DEoD and OC/DEopD sequences the physical properties decrease with xylanase treatment. There is no difference in the physical properties between XO and OX sequences. COD, BOD and color of bleaching effluents increase slightly with xylanase treatment, however the discharge of COD end-load into environmental impact decrease.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.670-675
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• 1999

6-[1-(4-Ribitylanilino)ethyl]-1,3,7-trimethyllumazine (2), which is related to pteridine moiety of methanopterin, was synthesized. 4-Ribitylaniline derivative was prepared from D-ribose and N-benzoyl-4-bromoaniline (7) as the starting materials through several steps. 6-Acetyl-1,3,7-trimethyllumazine (4) was obtained from the reaction of 4-amino-1,3-dimethyI-5-nitrosouracil (3) with 2,4-pentanedione by Timmis reaction. Compound 4 was converted to 6-(1-chloroethyl)-1,3,7-trimethyllumazin (6) by the reduction with sodium borohydride and followed by chlorination with thionyl chloride. The nucleophilic displacement reaction of compound 6 with 4-(2,3:4,5-di-O-iso-propylidene-D-ribityl)aniline (13) in anhydrous DMF yielded 6-[1-{4-(2,3:4,5-di-O-isopropylidene-D-ribityl)anilino}ethyl]-1,3,7-trimethyllumazine (14). The target molecule 2 was obtained by the hydrolysis of compound 14 in the presence of an acid catalyst.

• Journal of Environmental Science International
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• v.18 no.3
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• pp.289-298
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• 2009

The blue-green algae which caused odor problem in the tap water are difficult to precipitate in sedimentation basin and clogged the filter void rapidly. The studies of this paper were not only oxidation, coagulation and sedimentation processes for effectively removing blue-green algae but yellow clay and polyamine for verification as coagulants aids. The results of this research are summarized as follows: Higher ozone dose(C) and longer contact time(T) were needed for a high degree of removing blue-green algae efficiency. the removal rate of blue-green algae was proportional to the $C\times T$ value. The removal percent of chlorophyll-a by sedimentation and filter without pre-ozonation was about 75% but 1 mg/L pre-ozonation could increase the removal percent of chlorophyll-a to 99% and more pre-ozonation could remove completely. Though the removal efficiency of turbidity could increased by high dose of chlorination, the dissolved organic carbon was increased. More chlorine dose from 4 to 10 mg/L dissolved organic carbon was decreased. Using yellow clay as coagulant aids increased density of floc so the settling velocity of floc become rising but polyamine could not increase settling velocity of floc though it could formated large floc.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1153-1160
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• 2013

While a range of natural organic matter (NOM) types can generate high levels of disinfection by-products (DBPs) after chlorination, there is little understanding of which specific compounds act as precursors. Use of eight model compounds allows linking of explicit properties to treatability and DBP formation potential (DBPFP). The removal of model compounds by various treatment processes and their haloacetic acid formation potential (HAAFP) before and after treatment were recorded. The model compounds comprised a range of hydrophobic (HPO) and hydrophilic (HPI) neutral and anionic compounds. On the treatment processes, an ozone oxidation process was moderate for control of model compounds, while the HPO-neutral compound was most treatable with activated carbon process. Biodegradation was successful in removing amino acids, while coagulation and ion exchange process had little effect on neutral molecules. Although compared with the HPO compounds the HPI compounds had low HAAFP the ozone oxidation and biodegradation were capable of increasing their HAAFP. In situations where neutral or HPI molecules have high DBPFP additional treatments may be required to remove recalcitrant NOM and control DBPs.

• Journal of the Korean Electrochemical Society
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• v.15 no.4
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• pp.242-248
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• 2012

The measurement of residual chlorine as a disinfectant is very important to ensure the safety against the pathogenic microbes and to suppress injection. The portable free chlorine sensor was fabricated with a disposable strip format by a screen printing method. The strip sensors prepared with a carbon-Ag/AgCl(cathode-anode) combination exhibited less interfering responses towards combined chlorine species(especially $NHCl_2$) and oxygen than the sensors prepared with other metals(i.e., gold and platinum). Free chlorine was determined chronoamperometrically with carbon-based electrodes at an applied potential of -0.3 V(vs. Ag/AgCl). A channel was built on the strip-type electrode for easy sampling, and the resulting strip sensors were employed to determine the concentrations of residual free chlorine.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.179-182
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• 2001

The chloride volatilization method for the recovery of zirconium and removal of uranium from zirconium containing metallic wastes formed in spent fuel reprocessing was studied using the simulated alloy waste, i.e. the mixture of Zr foil and UO$_2$/U$_3$O$_{8}$ powder. When the simulated waste was heated to react with chlorine gas at 350- l00$0^{\circ}C$, the zirconium metal changed to volatile ZrCl$_4$showing high volatility ratio (Vzr) of 99%. The amount of volatilized uranium increases at higher temperatures causing lowering of decontamination factor (DF) of uranium. This is thought to be caused by the chlorination of UO$_2$ with ZrCl$_4$vapor. The highest DF value of 12.5 was obtained when the reaction temperature was 35$0^{\circ}C$. Addition of 10 vol.% oxygen gas into chlorine gas was effective for suppressing the volatilization of uranium, while the volatilization ratio of zirconium was decreased to 68% with the addition of 20 vol.% oxygen. In the case of the mixture of Zr foil and U$_3$O$_{8}$, the V value of uranium showed minimum (44%) at 40$0^{\circ}C$ with chlorine gas giving the highest DF value 24.3. When the 10 vol.% oxygen was added to chlorine gas, the V value of zirconium decreased to 82% at $600^{\circ}C$, but almost all the uranium volatilized (Vu=99%), which may be caused by the formation of volatile uranium chlorides under oxidative atmosphere.ere.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.501-508
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• 1994

1-Ethyl-6-fluoro-1, 4-dihydro-4-oxo-7-(1-piperazinyl)quinolinea-3-car-boxylic acid-dextran was synthesized by the reaction of 1-ethyl-6-fluoro-1, 4-dihydro-4-oxo-7-(1-piperazinyl )quinoline-3-acryloyl chloride with dextran. Polymeric drug was tested for antimicrobial activity in vitro against ten species of microorganisms. Polymeric drug revealed good antibacterial activity against Bacillus subtillis ATCC 6633, Staphyloccus aureus ATCC 25923, Mycrobactertum phlei IFO 3158, Salmonella typhimurium KCTC 1925, Escherichia coli KCTC 1039, Escherichia coli ESS, Klebsiella puemouiae KCTC 1560 and Pseudomonas aeruginosa IFO 13130. Polymeric drug have no antimicrobial against Candida albicans ATCC 10231, but moderately active Micrococcus luteus ATCC 9341.