• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.3-7
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• 2005

In the present study a feasibility of a novel filtration process using synthetic for secondary effluent reclamation was investigated. Polyurethane was chosen as a filter medium among tested three media. Compressibility and up-flow velocity were changed to determine the optimum operation for the system. An equation was introduced to express the relationship between the removal efficiency and up-flow velocity. In pilot study, the synthetic medium filtration with compression showed very stable effluent quality without clogging trouble, though the system operated with 3 times higher filtration rate and much longer backwashing interval than conventional systems.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.3
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• pp.377-384
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• 2004

In the present study, a feasibility of an advanced oxidation process using UV/Hydrogen peroxide($H_2O_2$) system equipped with a medium pressure lamp for secondary effluent reclamation was investigated. Initial concentration of $H_2O_2$ and pH were changed to determine the optimum operation condition for the system. The removal efficiency of color was than 80% with 14.3mg/L of initial $H_2O_2$ and 5 minute of contact time in the UV/$H_2O_2$ system. The color removal was analyzed using first-order reaction equation. The dependence of rate constant (k) on initial $H_2O_2$ represented the rational relationship with maximum value. Residual $H_2O_2$ caused increase of effluent COD, since analyzing agent, dichromate, reacted with $H_2O_2$ in the sample. Therefore, excess initial concentration of $H_2O_2$ would significantly affect effluent COD measurement. At pH variation experiment, both residual $H_2O_2$ and color showed peak in the neutral pH range with the same pattern. Effect of $H_2O_2$ dose also enhanced color removal but raised residual $H_2O_2$ problem in the continuous operation UV system. In conclusion, these results indicated that medium pressure UV/$H_2O_2$ system could be used to control color in the secondary effluent for reclamation and reuse.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.335-342
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• 2011

Secondary effluent contains particle compounds which are comprised of microorganisms that occurs membrane fouling when the water is reused. This study evaluates the characteristics of membrane fouling of secondary effluent reuse. Effects of chemical backwashing are analyzed to reduce membrane fouling by regular chemical backwashing. As the result, major membrane foulants are verified EPS materials which include protein and polysaccharide that cause biofilm cake layer on the membrane. Also, sodium hypochlorite is applied to chemical backwashing. The backwashing improves recover rate when injected chemical concentration is increased and chemical backwashing cycle is amplified. Chemical backwashing cycle affects more than injected chemical concentration yet idle time does not noticeably influence on reducing membrane fouling.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.443-451
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• 2012

Wastewater treatment plants need to reduce phosphorus in order to meet increasingly stringent regulations on phosphorus. This study evaluated the feasibility of dolomite as a coagulation aid to enhance phosphorus removal from secondary treated wastewater by chemical coagulation. Standard jar tests were conducted to evaluate the effect of dolomite addition on a coagulation process for phosphorus removal and to determine the optimum doses of coagulants and dolomite. Coagulants used with dolomite yielded a significant improvement in phosphorus removal and reduced total phosphorus concentrations below 0.02 mg/L in wastewater effluent. Dolomite has played an important role in enhancing phosphate adsorption and increasing pH, as a coagulation aid. The maximum removal efficiency of phosphorus in this study was yielded at 25 mg/l of dolomite and 20 mg Al/L of PAC dose. However, considering economic aspects, the optimum doses of dolomite and PAC were 10 mg/L and 15mg Al/L, respectively. Consequently, dolomite, a coagulation aid, can be used in coagulation processes to enhance the removal of phosphorus.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.605-612
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• 2005

The objective of this study was to evaluate the factors affecting the optimization of coagulation hybrid UF membrane processes for the reuse of secondary effluent from sewage treatment plant. The experimental results obtained from the UF membrane process showed that organic colloids in the size range of $0.2{\mu}m{\sim}1.0{\mu}m$ caused the most substantial influence on the fouling of UF membrane. When using a coagulation pretreatment to UF membrane, alum dosage of 50mg/L resulted in the least reduction in membrane permeate flux. Also, for the rapid mixing process, in-line mixer type was more efficient for organic removal than back mixer type. Therefore, it may be concluded that coagulation-UF hybrid membrane process comparing to UF alone process showed not only higher removal efficiency of organic matter, but also substantial improvement of permeate flux of UF membrane.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.361-367
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• 2016

Pollutants removal and disinfection effect of secondary effluent from final settling tank of sewage treatment plant of W city were investigated in Loop Reactor using ordinary granular activated carbon(GAC) and GAC coated with silver nanoparticles. The results showed that the removal efficiency of $COD_{Mn}$, T-N and T-P using GAC with silver nanoparticles were higher than using the ordinary GAC. The removal efficiency of T-P using GAC with silver nanoparticles is 45.4% and that of T-P using ordinary GAC is 30.9% in the same case of the input amount of 20 g/L of GAC. The total califorms is reduced according to increasing input amount of GAC with silver nanoparticles and ordinary GAC. The disinfection efficiency of total coliforms in case of GAC with silver nanoparticles is much higher than that in case of ordinary GAC. For all experiments using the silver nanoparticles, the total coliforms is under 26 cfu/mL and this shows very excellent disinfection effect.

• Journal of Korean Society of Water and Wastewater
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• v.17 no.4
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• pp.542-549
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• 2003

In the present study, the feasibility of $UV/H_2O_2$ systems was investigated using low and medium-pressure lamps on biologically treated wastewater effluents for secondary effluent reclamation. Two types of UV lamps were used as the light sources (a 39-W low-pressure mercury lamp and a 350-W medium-pressure mercury lamp). The results from these UV systems showed that the removal of organic compounds could be achieved in the contact time of longer than 30min (i.e., low UV doses). Efficiencies of color removal and disinfection were far better than those of organic matters measured as TOC, DOC and $TCOD_{cr}$. In the low-pressure lamp UV system, it has been found that DOC and color removals were 60.9 and 86.2% with 50mg/L of $H_2O_2$ and contact times of 30 minute, respectively. Whereas, with the medium-pressure lamp UV system, TOC, DOC and color removal were 27.1, 5.6 and 95% with 14.3mg/L of $H_2O_2$ and 14 minute of contact times, respectively. Both systems could be applied for the reclamation of secondary effluent treated with biological treatment processes.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.657-668
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• 2014

Under Korea's Enforcement Decree of the Framework Act on Environmental Policy amended in 2013, total organic carbon (TOC) is newly added as water quality parameter to assess organic pollution in water and aquatic ecosystem. To meet the TOC requirement and improve quality of effluent discharged into public watershed, it is also necessary to develop standards for TOC in effluent from public sewage treatment works (PSTWs). In this study, we reviewed the characteristics and removal efficiency of TOC in influent and effluent of PSTWs. The study found that phosphorus treatment process removed not only soluble phosphorus but also a portion of TOC remaining after the secondary treatment process. TOC concentration in effluent from PSTWs operated in tandem with industrial wastewater treatment work was higher due to influx of insoluble substances from the industrial wastewater treatment work. In order to lay a foundation for the management of TOC from PSTWs, it is necessary to carry out research on TOC from different perspectives. For example, studies on the generation mechanism of TOC and the impact of TOC on drinking water resources, assessment of effluent qualities through monitoring, and development of measures to control TOC for the preservation of aquatic ecosystem are needed.

• KSBB Journal
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• v.29 no.5
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• pp.353-360
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• 2014

This study targets the pollutant removal of secondary effluent from final clarifiers in wastewater treatment plant using silver nanoparticles on activated carbon. The removal efficiency and treatment characteristics of pollutant are anlayzed by perfoming experiments using granular activated carbon with silver nanoparticles and ordinary granular activated carbon. The specific surface area of granular activated carbon with silver nanoparticles is smaller than that of ordinary granular activated carbon. However, the removal efficiency of $COD_{Mn}$, T-N and T-P in experiments using activated carbon with silver nanoparticles are higher than that in experiment using ordinary granular activated carbon. That means the case of activated carbon with silver nanoparticles is much better at treatment activity. In addition, activated carbon with silver nanoparticles has antimicrobial activity because there is no microbe on the surface of it after experiments.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.471-478
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• 2012

Where an activated sludge system needs to be converted to biological nutrient removal(BNR) system, the secondary clarifier must handle higher MLSS from bioreactor since nitrification in BNR system that requires higher SRTs than activated sludge system. Either increase the clarifier size or modification of clarifier physical structure is required to cope with MLSS surge. One of recommended structural modification is the insertion of Lamellar within clarifier. In this study, two clarifiers - one has Lamellar structure inserted and the other does not - were used to compare the effect of Lamellar in solid/liquid separation. Same MLSS was fed to both clarifiers and concentrations of MLSS were varied. With all MLSS concentrations, attachment of MLSS on Lamellar was observed and it was found that detached MLSS caused the higher effluent SS concentrations than that of non-Lamellar clarifier effluent. From these results, Lamellar should not be inserted in clarifier to handle MLSS from BNR processes and the recommendation must be withdrawn.