• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.429-437
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• 2007

This study aims to develop a sulfur-using denitrification process which is possible a renovation to advanced treatment plant submerging a simple module in activated sludge aeration tank. At first, the impact factor of sulfur-using denitrification was appreciated by the batch test. Secondly, reflecting a dissolved oxygen effect of sulfur-using denitrification that was confirmed by the batch test, in a continuous nitrification/sulfur-using denitrification, high-rate nitrogen removal reaction was induced at optimum condition controlling DO concentration according to phases. Also, inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. Result of batch test for sulfur-using denitrification, $NO_2{^-}N$ was lower for consumption of alkalinity and sulfur than that of $NO_3{^-}-N$. These results revealed the accordance of theoretical prediction. In continuous nitrification/sulfur-using denitrification experiment, actual wastewater was used as a influent, and influent nitrogen loading rates were increased 0.04, 0.07, 0.11, $0.14kg\;N/m^3-day$ by changing hydraulic retention times. At this time, nitrogen loading rates of packed sulfur were increased 0.23, 0.46, 0.69, $0.93kg\;N/m^3-day$. As a result, nitrification efficiency was about 100% and denitrification efficiency was 93, 81, 79, 72%. Accordingly, nitrogen removal was a high-rate. Also the module of sulfur-using denitrification covered with microfilter did not make a fouling phenomena according to increased flux. And the module was achieved effluent suspended solids of below 10 mg/L without a clarifier. In conclusion, it is possible a renovation to advanced treatment plant submerging a simple module packed sulfur in activated sludge aeration tank of traditional facilities. And the plant used the module packed sulfur is expected as a effective facilities of high-rate and the smallest.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.481-488
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• 2011

Various development activities have lead to the destruction of the ecosystem such as natural wetlands. In order to protect these natural wetlands, the Ministry of Environment (MOE) in Korea enacted the Wetland Conservation Act in 1999 and designated protected areas for wetland conservation. The MOE adapted the use of Best Management Practices (BMP) such as retention ponds and constructed wetlands to treat the polluted water before entering the water system. One of these projects was a free-water surface flow (FWS) constructed wetland built as a secondary treatment unit for piggery wastewater effluent coming from a livestock wastewater treatment facility. Water quality monitoring for the constructed wetland was conducted during rainfall events. The results showed that the average removal efficiencies of TSS, BOD, TN, TP were 86, 60, 45, 70%, respectively. It was observed that the removal efficiency of particulate matter and phosphorus was high compared to nitrogen. Therefore, a longer hydraulic retention time was needed in order to improve the treatment efficiency of nitrogen. The results of this study can contribute to the wetland design, operation and maintenance of constructed wetlands.

• Membrane Journal
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• v.24 no.5
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• pp.350-357
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• 2014

Pressurized MF membranes are used to remove suspended solid and colloidal materials of wastewater treatment plant effluent as the pretreatment of RO in reuse water production process. Membrane operation data and pollutants removal efficiency are investigated using 100 t/d scale pilot plant in J wastewater treatment plant located in Namyangju city. 40 LMH flux of pressurized MF membrane are obtained in various turbidity and temperature condition. Coagulation of dissolved organic enables flux improvement of MF from 40 LMH to 60 LMH. Pressure drop of 1st RO elements rapidly increased after long-term pause, which is because the complex contamination of organic matter and ionic substances of pluming systems.

• Journal of Environmental Science International
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• v.1 no.2
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• pp.125-136
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• 1992

Digestion of a municipal wastewater sludge by the anaerobic sequencing batch reactor (ASBR) was investigated to evaluate the performance of the ASBR process at a critical condition of high-solids-content fined. The reactors were operated at an HRT of 10 days with an equivalent loading rate of 0.8-1.5 gVS/L/d at 35$^{\circ}C$ The main conclusions drawn from this study were as follows: 1. Digestion of a municipal wastewater sludge was possible using the ASBR in spite of high concentration of settleable solids in the sludge. The ASBRS with 3- and 4-day cycle period showed almost identical high digestion performances. 2. No adverse effect on digestion stability was observed In the ASBRS in spite of withdrawal and replenishment of 30% or 40% of liquid contents. A conventional anaerobic digester could be easily converted to the ASBR without any stability problem. 3. Flotation thickening occurred in thicken step of the ASBRS throughout steady state, and floating bed volume at the end of thicken period occupied about 70% of the working volume of the reactor Efficiency of flotation thickening in the ASBRS could be comparable to that of additional gravity thickening of a completely mixed digester. 4. Solids were accumulated rapidly in the ASBR during start-up period. Solids concentrations in the ASBRS were 2.6 times higher than that in the completely mixed control reactor at steady state. Dehydrogenase activity had a strong correlation with the solids concentration. Dehydrogenase activity of the digested flu형e in the ASBR was 2.9 times higher than that of the flu형e in the control reactor, and about 25 times higher than that of the subnatant in the ASBR. 5. Remarkable increase in equivalent gas production of 52% was observed at the ASBRS compared with the control reactor in spite of similar quality of clarified effluent from the ASBRS and control reactor. The increase in gas production from the ASBRS was believed to be combined results of accumulation of microorganisms, higher driving force applied, and additional long-term degradation of organics continuously accumulated.

• Environmental Engineering Research
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• v.20 no.1
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• pp.79-87
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• 2015

To treat leather industry wastewater (LIW) containing high nitrogen concentration, eight aerobic denitrifiers were isolated from sludge existing in an LIW-treatment aeration tank. Among them, one strain named as KH8 had showed the great ability in denitrification under an aerobic condition, and it was identified as Pseudomonas aeruginosa R12. The aerobic denitrification ability of the strain KH8 was almost comparable to its anaerobic denitrification ability. In lab-scale aerobic denitrifications performed in 1-L five-neck flasks for 48 hr, denitrification efficiency was found to be much improved as the strain KH8 held a great majority in the seeded cells. From the nitrogen balance at the cell-combination ratio of 10:1 (the strain KH8 to the other seven isolates) within the seeded cells, the percentage of nitrogen loss during the aerobic denitrification process was estimated to be 58.4, which was presumed to be converted to $N_2$ gas. When these seeded cells with lactose were applied to plant-scale aeration tank for 56 day to treat high-strength nitrogen in LIW, the removal efficiencies of $COD_{Cr}$ and TN were achieved to be 97.0% and 89.8%, respectively. Under this treatment, the final water quality of the effluent leaving the treatment plant was good enough to meet the water-quality standards. Consequently, the isolated aerobic denitrifiers could be suitable for the additional requirement of nitrogen removal in a limited aeration-tank capacity. To the best of our knowledge, this is the first report of aerobic denitrifiers applied to plant-scale LIW treatment.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.269-276
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• 2012

The surface characteristics and performance of PTFE (polytetrafluoroethylene) hollow fiber membranes have been systematically investigated at lab- and pilot-scale to assess their application to membrane-bioreactor, particularly for integrating wastewater reclamation and rainwater harvesting. The PTFE membrane expressed some surface features, such as hydrophobicity, which might enhance membrane fouling. However, lab-scale performance and cleaning experiments under various conditions demonstrated that the PTFE membrane could produce the desirable water flux with good cleaning efficiency, implying easy operation and maintenance due to superior chemical resistance of PTFE membranes. Most of effluent water qualities were met with Korean standard for discharge and reuse, except color. Color level was further reduced by blending with rainwater at 75:25 ratio. Based on the lab-scale experimental results, the pilot plant was designed and operated. Pilot operation clearly showed sTable performance with satisfactory water quality, suggesting that PTFE membrane could be applied for decentralized MBR integrated with rainwater use.

• Journal of Environmental Science International
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• v.18 no.2
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• pp.205-213
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• 2009

A laboratory experiment was conducted to investigate nitrogen removal from plating wastewater by a soil reactor. A combination of soil, waste oyster shell and activated sludge were used as a loading media in a soil reactor. The addition of 20% waste oyster shell and activated sludge to the soil accelerated nitrification (88.6% ${NH_4}^{+}-N$ removal efficiency) and denitrification (84.3% ${NO_3}^{-}-N$ removal) in the soil reactor, respectively. In continuous removal, the influent ${NH_4}^{+}-N$ was mostly converted to nitrate nitrogen in the nitrification soil reactor and only a small amount of ${NH_4}^{+}-N$ was found in the effluent. When methanol was added as a carbon source to the denitrification soil reactor, the average removal efficiency of ${NO_3}^{-}-N$ significantly increased. The ${NO_3}^{-}-N$ removal by methanol addition in the denitrification soil reactor was mainly due to denitrification. The phosphorus was removed by the waste oyster shell media in the nitrification soil reactor. Moreover, the phosphorus removal in the denitrification soil reactor was achieved by synthesis of bacteria and the denitrification under anaerobic conditions. The approximate number of nitrifiers and denitrifiers was $3.3{\times}10^5\;MPN/g$ soil at a depth of $1{\sim}10\;cm$ and $3.3{\times}10^6\;MPN/g$ soil at a depth of $10{\sim}20\;cm$, respectively, in the soil reactor mixed with a waste oyster shell media and activated sludge.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.317-324
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• 2018

SWRO-PRO hybrid desalination technology is recently getting more attention especially in large desalination markets such as USA, Middle East, Japan, Singapore, etc. because of its promising potential to recover a considerable amount of osmotic energy from brine (a high-concentration solution of salt, 60,000 - 80,000 mg/L) and also to minimize the impact of the discharged brine into a marine ecosystem. By the research and development of the core technologies of the SWRO-PRO desalination system in a national desalination research project (Global MVP) supported by Ministry of Land, Infrastructure, and Transport (MOLIT) and Korea Agency for Infrastructure Technology Advancement (KAIA), it is anticipated that around 25% of total energy consumption rate (generally 3 to $4kWh/m^3$) of the SWRO desalination can be reduced by recovering the brine's osmotic energy utilizing wastewater treatment effluent as a PRO feed solution and an isobaric pressure exchanger (PX, ERI) as a PRO energy converter. However, there are still several challenges needed to be overcome in order to ultimately commercialize the novel SWRO-PRO process. They include system optimization and integration, development of efficient PRO membrane and module, development of PRO membrane fouling control technology, development of design and operation technology for the system scaling-up, development of diverse business models, and so on. In this paper, the current status and progress of the pilot study of the newly developed SWRO-PRO hybrid desalination technology is discussed.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.339-345
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• 2004

The characteristics of $H_2$ production from livestock wastewater were investigated through an anaerobic acid forming process using Clostridium beijerinckii and the photosynthetic process using Rhodobacter sphaeroides. The submerged separation membrane was installed in the acid forming reactor, The photosynthetic process is composed of two reactors(photosynthetic reactor 1 and photosynthetic reactor 2) which is connected continually. The removal rate of COD and the production of volatile fatty acid(VFA) in the acid forming process were approximately 50% and 1000mg/L, respectively. The 70% of COD in the effluent of acid forming process was removed through the photosynthetic process. The production of $H_2$ in the photosynthetic reactor 1 and 2 was 50 and $25mLH_2/gVFA_{COD}$, respectively. The values of Y in acid forming reactor, photosynthetic reactor 1 and 2 was 0.2263, 0.0601 and 0.0393, respectively. The acetic acid and butyric acid produced in acid forming process were converted to $H_2$ by photosynthetic bacteria.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.27-32
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• 2007

This study focused on estimating the feasibility of a strong basic anion exchanger (PA312OH) as a sorbent for the removal of residual reactive dye and saving chemicals and water. Cellulose reactive dye C.I.RB49 was tested because reactive dye is the largest single group of dyes and that dye needs larger amount of inorganic salts as dyeing agent but nearly 50% of reactive dyes may be lost to the effluent. The adsorption characteristics of PA312OH for C.I.RB49 were as follows. Ion-selectivity among the dye and inorganic salts was Dye > ${SO_4}^{2-}$ > ${CO_3}^{2-}$ > $Cl^-$. C.I.RB49 was exchanged more than 3 times ${SO_4}^{2-}$ and ${CO_3}^{2-}$ and $Cl^-$ was not exchanged absolutely. The exchanging velocity was increased exponentially with increasing temperature. This result is positive effect on treating the high temperature dyeing process wastewater. The exchanged dye percents to initial were 96.8% and 99% at flow rate 20.5 mL/min. and 3.7 mL/min.. The exchanging capacity of PA312OH for C.I.RB49 was 215.2 mg/g at conc.=369.2 mg/L, Temp.=$25^{\circ}C$. 74% inorganic salts were recrystallized from real dark reactive color dyeing wastewater treated with PA312OH.