• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_2
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• pp.79-88
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• 2001

Humic acids react with chlorine to produce Trihalomethanes(THMs), known as carcinogens, during disinfection, the last stage in water purification. Currently, the removal of organic humic acids is considered the best approach to solve the problem of THM formation. Accordingly, the current study examined the adsorption of organic compounds of humic acids onto an inorganic carrier prepared from oyster shell waste. The adsorbent used was activated oyster shell powder(HAP) and silver ion-exchanged oyster shell powder(HAP-Ag), with CaCO$_3$ as the control. The adsorbates were phthalic acid, chelidamic acid, catechol, dodecylpyridinium chloride(DP), and 2-ethyl phenol(2-EP). The adsorption experiments were carried out in a batch shaker at $25^{\circ}C$ for 15 hours. The equilibrium concentration of the adsorbate solution was analyzed using a UV spectrophotometer and the data fitted to the Langmuir isotherm model. Since the solution pH values were found to be greater than the pKa values of the organic compounds used as adsorbates, the compounds apparently existed in ionic form. The adsorptive affinities of the organic acid and phenolic compounds varied depending on the interaction of electrostatic forces, ion exchange, and chelation. More carboxylic acids and catechol, rather than DP and 2-EP, were adsorbed onto HAP and HAP-Ag. HAP and HAP-Ag exhibited a greater adsorptive affinity for the organic compounds than CaCO$_3$, used as the control.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.798-807
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• 2008

Due to economic impairment derived from metal corrosion of pumping station installed around coastal area, it was needed for related cause-effect to be investigated for understanding practical corrosion behavior and providing proper control. This research was thus carried out to determine whether the microbe can influence on metal corrosion along with its control in the laboratory. For this study, groundwater was sampled from the underground pump station(i.e. I Gas Station) where corrosion was observed. Microbial diversity on the samples were then obtained by 16S rDNA methods. From this, microbial populations showing corrosion behaviors against metals were reported as Leptothrix sp.(Iron oxidizing) and Desulfovibrio sp.(Sulfur reducing) Iron oxidizing bacteria were dominantly participating in the corrosion of iron, while sulfate reducing bacteria were more preferably producing precipitate of iron. In case of galvanized steel and stainless steel, iron oxidizing bacteria not only enhanced the corrosion, but also generated its scale of precipitate. Sulfate reducing bacteria had zinc steel corroded greater extent than that of iron oxidizing bacteria. In the inactivation test, chlorine or UV exposure could efficiently control bacterial growth. However as the inactivation intensity being increased beyond a threshold level, corrosion rate was unlikely escalated due to augmented chemical effect. It is decided that microbial corrosion could be differently taken place depending upon type of microbes or materials, although they were highly correlated. It could be efficiently retarded by given disinfection practices.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.1-6
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• 2012

Down Stream K River has high COD (4-10 mg/L) and high $NH_3$-N concentration (3.5 mg/L during winter period). Although $NH_3$-N itself is not reported harmful at this level, it must be removed to meet drinking water standard (0.5 mg/L). We constructed a pilot plant modifying the processes of conventional drinking water facilities. Prechlorination and powdered activated carbon (PAC) dechlorination was adopted prior to a flocculation tank to remove ammonia and prevent disinfection byproducts (DBPs) formation. Also, GAC processes was included after sand filter to remove residual DOC. This pilot having a capacity of 36 ton/day was operated for one year. The GAC processes were successful to remove ammonia and many organic pollutants (DOC, MBAS, UV-254 nm absorbance, etc). Influent DOC concentrations were very high as 3~6 mg/L throughout the plant operation. It was impossible to achieve 1.0 mg/L effluent DOC, indicating that bed depth (2 m) should be increased to achieve more strict DOC quality standards. When $Cl_2$ dose was well controlled ($Cl_2/NH_3$-N ratio 10~11 on a weight basis), $NH_3$-N removal was 98% and THMs was very low possibly due to low free residual chlorine and PAC dechlorination.

• Journal of Environmental Science International
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• v.15 no.8
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• pp.785-797
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• 2006

The formation characteristics of trihalomethanes (THMs) and haloacetic acids (HAAs) were investigated in chlorination of raw water of different organic mallet characteristics. The samples used in this study were hydrophobic (N-HPO) and hydrophilic fraction (N-HPI) (which were concentrated and separated from Nakdong river water), and humic acid (HA) (which is known as a strong hydrophobic acid) as a reference organic matter, the specific UV absorbance (SUVA) of which was 2.19, 1.15 and 7.92, respectively. With increasing chlorine contact time, THMFP and HAAFP (the formation potential of THMs and HAAs) increased, but their increase was different depending on the organic mallet characteristics (i.e., for N-HPI, THMFP was higher than HAAFP, but the inverse result was obtained for N-HPO and HA and the ratio between them was greater for HA), and the mainly formed chemical species were CHCI$_3$ in case of THMs and dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in case of HAAs for N-HPO and HA (and the ratios of CHCI$_3$ to total THMs and DCAA and TCAA to total HAAs for HA were higher than those for N-HPO), but for N-HPI, the ratio of brominated THMs was a little higher than that of CHCI$_3$ and the ratio of DCAA and TCAA to total HAAs was lower than that of N-HPO, although they are main chemical species in case of HAAs. Comparing THMFP and HAAFP with the increase in bromide concentration added with those in not adding it, the former increased greatly and its increase was higher for the organic mallet with stronger hydrophobicity, but the latter was lower for N-HPO and N-HPI and was similar for HA. The main chemical species with increasing bromide concentration were CHBt$_3$ in case of THMs regardless of organic matter characteristics, and dibromoacetic acid (DBAA) for N-HPO and N-HPI, DBAA and tribromoacetic acid (TBAA) for HA in case of HAAs. With increasing reaction temperature and pH, THMFP and HAAFP increased for the former, but for the latter, THMFP increased and HAAFP decreased, although the rate of increase or decrease was different with organic mallet characteristics.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1099-1107
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• 2005

The purpose of this study was to find the transformation of organic matter as well as chlorine by product formation potential with ozone dosage. The removal percents of $UV_{254}$ and DOC were $23%{\sim}65%$ and $2%{\sim}15%$ and THMFP and HAAFP were $17%{\sim}52%$ and $9%{\sim}29%$ respectively at $0.5{\sim}3\;mgO_3/mgDOC$ ozone dosage. The hydrophobic and transphobic organic matter were reduced to $37%{\sim}68%$ and $35%{\sim}64%$, on the other hand the hydrophilir organic matter was increased to $40%{\sim}49%$ at $0.5{\sim}3\;mgO_3/mgDOC$ ozone dosage. The produced THMFP and HAAFP from the hydrophobic and transphilic organic matter were decreased greatly with increasing ozone dosage but these by products were increased in the hydrophilic matter. The produced THMFP and HAAFP per unit DOC were decreased and reactivity was reduced greatly with increasing crone dosage. The removal rate of THMFP per unit DOC was much higher than HAAFP by ozone treatment. The Br-THMFP per unit DOC was much more removed than chloroformFP per unit DOC with increasing ozone dosage. and The removal rate of TCAAFP per unit DOC was increased with increasing ozone dosage but TCAAFP was not affected by ozone treatment. Br-HAAFP was decreased at $1\;mgO_3/mgDOC$ ozone dosage but was not more removed above $1\;mgO_3/mgDOC$ ozone dosage. Br-HAAFP had lower removal effect than Br-THMFP by ozone treatment. The optimal ozone dosage can be determined about $1\;mgO_3/mgDOC$ by considering both disinfection by product formation and economical efficiency.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.281-287
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• 2011

BACKGROUND: According to Korean regulations, bottled waters (BWs) can not be treated with chemical disinfectants like chlorine, so UV and ozone disinfection is applied. During the past several years, chemicals were detected in some BWs, and the public was concerned about the safety of BWs. METHODS AND RESULTS: Mineral waters were stored for 180 days at $25^{\circ}C$ and $50^{\circ}C$, tested acetaldehyde and formaldehyde by HPLC. When mineral waters were put in a PET bottles, the formaldehyde level ranged from 5 to $66{\mu}g/L$ during 180 days at $50^{\circ}C$. While the acetaldehyde level ranged from 31 to $221{\mu}g/L$, it was low than $16{\mu}g/L$ in glass bottle. CONCLUSION(s): This result showed that formaldehyde and acetaldehyde were detected higher in PET bottles than glass bottles, these also increased depending on the time of storage. Concentration of formaldehyde and acetaldehyde could be significantly influenced by the time of storage and temperature.