• Journal of Environmental Science International
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• v.8 no.3
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• pp.337-347
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• 1999

This study was carried out to evaluate the characteristics of dissolved organics based on their origins, which were divided into two categories. The first group consisted of river, lake and secondary sewage treatment effluent, which were chosen as representative of their origins. The second group were artificial samples which were made of AHA(Aldrich humic acids) and WHA(Wako humic acids). Physicochemical characteristics, biological degradability and THMEP(trihalomethane formation potential) of the samples were analysed based on the AMWD(apparent molecular weight distribution). Large portion of dissolved organic carbon(DOC) in the river and lake samples was comprised of LMW(low molecular weight), which that of AHA and WHA was HMW(high molecular weight). The DOC of the lake was evenly distributed in the all range of molecular weight. The river, lake and secondary treated effluent have lower ultraviolet(UV) absorbance at 254nm, and have a higher amount of humic acids. Higher absorbance of humic acids means that aliphatic bond and benzenoid type components that absorb UV light were contained in these kind of humic acids. It was expected that lake sample was the most biodegradable in the different samples investigated, and in order of secondary sewage treatment effluent, river, WHA and AHA based on the result of determination of specific ultraviolet absorbance(SUVA). Biodegradability showed similar result except for AHA, while dissolved organics in the range of LMW decreased during the biodegradability test, and on the contrary those of HMW increased. Production of the SMPs(soluble micobial products) was observed during humicfication of dissolved organics and the SMPs were higher production of the SMPs. THM formation was high in the samples containing HMW and similar tendency was shown in the THMEP(trihalomethane formation potential), except for WHA.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.743-750
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• 2008

In water treatment plant the Dissolved Ozone Flotation(DOF) System may be employed because this system has various abilities, such that it can remove SS using microbubbles, and it can exert strong oxidation power in removing taste and odor, color, and microbial agents. In order to investigate effectiveness of the DOF system in water treatment, removal characteristics of various water quality parameters were observed depending on the different levels of ozone concentrations. Removal efficiencies of water quality parameters in DOF system were compared with those in DAF(Dissolved Air Flotation) system and in CGS(Conventional Gravity Settling) system. Optimum ozone dose obtained in the pilot experiments was 2.7 mg/L. With increasing ozone dose higher than 2.7 mg/L, removal rates of turbidity, KMnO$_4$ consumption, UV$_{254}$ absorbance, and TOC were reversely lowered. High concentration of ozone dissociate organic matter in water, so that increasing dissolved organic level in effluent. Removal rates of water quality parameters at optimum ozone dose were obtained, such that removal rates of turbidity, KMnO$_4$ consumption, TOC, and UV$_{254}$ asorbance were 88.9%, 62.9%, 47%, and 77.3% respectively. Removal rate of THMFP was 51.6%. For all the parameters listed above, the DOF system was more effective than the DAF system or the CGS system. It is found that the DOF system may be used in advanced water treatment not only because the DOF system is more efficient in removing water quality parameters than the existing systems, but because the DOF system is also required smaller area than the CGS system for the treatment plant.

• Advances in environmental research
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• v.1 no.3
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• pp.181-189
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• 2012

Trihalomethanes, produced as a result of chlorination of drinking water, are considered a potential health hazard. The trihalomethane formation potential (THMFP) of a raw water source may indicate the maximum trihalomethanes (THMs) that are likely to be produced when chlorine reacts with natural organic matter (NOM) present in the water. A study was conducted to evaluate the THMFP in seven different drinking water sources in the vicinity of Kalpakkam, a rural township, on the east coast of India. Water from seven stations were analysed for THMFP. THMFP was compared with surrogate parameters such as dissolved organic carbon (DOC), ultraviolet absorbance ($UV_{254}$) and bromide. The data showed that THMFP was high in water from open wells as compared to closed bore wells, possibly due to more photosynthetic activity. Proximity to sea, and consequently the levels of bromide, was an important factor that influenced THM formation. THM surrogate parameters showed good correlation with THMFP.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.625-633
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• 2011

A long-term water quality monitoring in the Han River Basin reveals a consistent increasing trend for the concentration of refractory organic matter (R-OM) in major monitoring sites of the watershed. Because the determination of R-OM concentrations typically requires a long time of microbial incubation, it is essential to present the estimation indices for R-OM for an efficient watershed management. In this study, a number of surface water samples were classified into three groups, each of which were collected from Lake Paldang, rivers at rain and non-rain events, respectively. The corresponding R-OM concentrations were correlated with biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) concentrations as well as ultraviolet and fluorescence intensities of the filtered samples. Among the traditional organic matter parameters, TOC exhibited the highest correlation coefficient with the R-OM concentrations regardless of the types of the sample groups. The equations for conversing TOC into R-OM concentrations were finally suggested as $0.43{\times}TOC+1.12$, $0.44{\times}TOC+0.61$, $0.24{\times}TOC+1.28$ for river samples at rain and non-rain events, and lake samples, respectively. TOC-BOD(C), the values of the TOC concentrations subtracted by carbon-converted BOD concentrations, was a good index for estimating the absolute concentrations of R-OM. UV absorbance at 254 nm was well correlated with R-OM concentrations of river samples while fluorescence intensities at 350 nm showed an excellent relationship with R-OM concentration of the lake samples. Our results suggests that simple spectroscopic parameters could be applied for in-situ monitoring tool techniques in watersheds.

• Korean Membrane Journal
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• v.11 no.1
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• pp.21-28
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• 2009

We investigated the effect of organic materials on membrane fouling in advanced drinking water treatment by a hybrid module packed with granular activated carbon (GAC) outside multi-channel ceramic microfiltration membrane. Synthetic water was prepared with humic acid and kaolin to simulate natural water resouces consisting of natural organic matter and inorganic particles. Kaolin concentration was fixed at 30 mg/L and humic acid was changed as 2~10 mg/L to inspect the effect of organic matters. Periodic back-flushing using permeate water was performed for 10 sec per filtration of 10 min. As a result, both resistance of membrane fouling (Rf) and permeate flux (J) were influenced highly by concentration of humic acid. It proved that NOM like humic acid could be an important factor on membrane fouling in drinking water treatment. Turbidity and UV254 absorbance were removed up to above 97.4% and 59.2% respectively.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1162-1167
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• 2005

Livestock wastewater is known to be very difficult to treat because it contains highly non-biodegradable organic material. Thus the DOF(Dissolved Ozone Flotation) system and the PO2(Pressurized Ozone Oxidation) system were built at the livestock wastewater treatment plant, and characteristics of treatments were investigated in this paper. Suspended Solids(SS) removal efficiency was over 94% by DOF system. 90% of $COD_{Mn}$ was removed, from 620 mg/L down to 63 mg/L by the DOF-PO2 system. During the period of operation, $SCOD_{Cr}$ was removed an average of 82%, from 890 mg/L down to 160 mg/L. 96% of UV-254 absorbance was also removed. TP removal efficiency was over 98%, from 27 mg/L to 0.35 mg/L, and TN was also removed 68% along with suspended solids. It was possible to meet effluent standards of the livestock wastewater treatment plant by the DOF-PO2 system along with biological treatment.

• Membrane Journal
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• v.25 no.4
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• pp.358-366
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• 2015

Flat membrane with $0.4{\mu}m$ pore size was prepared with PVdF (polyvinylidene fluoride) nanofiber, which has the advantages such as excellent strength, chemical resistance, nontoxic, non-combustibility. After that, spiral wound module was manufactured with it including a woven paper. Effect of pH was studied by comparing permeate fluxes and rejection rates of the spiral wound module using simulation solution including kaolin and humic acid. The recovery rate and filtration resistance were calculated after water back-washing at the end of filtration experiment. In addition, after the water filtrated by the spiral wound module was passed through a column filled with GAC (granular activated carbon), adsorption effect of GAC was investigated by measuring the turbidity and $UV_{254}$ absorbance.

• 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.

• Membrane Journal
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• v.21 no.1
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• pp.72-83
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• 2011

For advanced drinking water treatment of high turbidity water, we used the hybrid module that was composed of photocatalyst packing between outside of tubular ceramic microfiltration membrane and membrane module inside. Photocatalyst was PP (polypropylene) bead coated $TiO_2$ powder by CVD (chemical vapor deposition) process. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. Water-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling. Resistance of membrane fouling ($R_f$) decreased and J increased as concentration of humic acid changed from 10 mg/L to 2 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiencies of turbidity and $UV_{254}$ absorbance were above 98.5% and 85.7%, respectively. As results of treatment portions by membrane filtration, photocatalyst adsorption, and photo-oxidation in MF, MF + $TiO_2$, and MF + $TiO_2$ + UV processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of humic acid by adsorption and photo-oxidation were above 10.7 and 8.6%, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.94-104
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• 1997

Ozone Treatment is getting a common process in a water treatment plant all over the nation. Especially an advanced water treatment using ozone and biofiltration has been a typical method in the regions where using the Nak-Dong River as a drinking water source. The effectiveness of ozone treatment in a continuous flow contact system was investigated with sand filtered water of the Nak-dong River. Pilot tests of the experiments were performed three times of the year like June, August, and October 1995. Most degradable organics of sand filtered water were oxidized in the first and second contact chamber of the system. Ozone treatment was effective for the removal of UV254 absorbance. However, Noticeable removals of $KMnO_4$ demand and TOC(Total Organic Carbon) were occurred when their concentrations exceeded about 5mg/l. The organics causing $KMnO_4$ demand and TOC were degraded into lower molecular matter in an early stage of the ozone contact in the system. Dissolved oxygen concentration was increased after ozone treatment.