• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.319-326
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• 2017

In this study, a lightweight geopolymer was prepared using by slag discharged from IGCC (Integrated Gasification Combined Cycle) power plant and its physical properties, the density and compressive strength, were analyzed as a function of the concentration of alkali activators, W/S ratio and aging times. Also the possibility of applying it to lightweight materials by adding Si sludge as a foaming agent to the geopolymerg was investigated. In particular, a complex composition of alkali activator and a pre-curing process were applied to improve the strength properties of lightweight geopolymers. While the compressive strength of the lightweight geopolymer using a single activator was 9.5 MPa, the specimen made with a complex composition of alkali activator had compressive strength of 2~5 times higher. In addition, the lightweight geopolymer with pre-curing process showed a compressive strength value of 18~48 % higher than that of specimen made with no precuring process. In this study, by using a complex activator and a pre-curing process. the maximum compressive strength of lightweight geopolymer was obtained as 40 MPa (The specimen was aged for 3 days and had density of $1.83g/cm^3$), which is comparable to cement concrete. By analyzing the crystal phase and microstructure of geopolymers obtained in this study using by XRD and SEM, respectively, it was confirmed that the flower-bud-like zeolite crystal was homogeneously distributed on the surface of the C-S-H gel (sodium silicate hydrate gel) in the geopolymer.

• Journal of Life Science
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• v.17 no.4 s.84
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• pp.510-514
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• 2007

This study was carried on cool and RT(room temperature) storage of unhulled rice. In RT storage of an analysis of coefficient relation, high significant positive coefficients were observed in toyo index and breakdown, setback and protein content. high significant negative coefficients were showed setback and breakdown, breakdown and protein content. In cool storage of an analysis of coefficient relation, high significant positive coefficients were observed in toyo index and amylose content and gelatinization start temperature and protein content and high significant negative coefficients were showed toyo index and whiteness, toyo index and gelatinization start temperature, gelatinization start temperature and amylose content. In RT storage of a path coefficient analysis, a highest positive direct influence was observed in amylose content and a highest negative direct influence was protein content. Positive indirect influence was high revealed breakdown and protein content and negative indirect influence was gelatinization start temperature and Mg/K ratio. In cool storage of a path coefficient analysis, a highest positive direct influence was whiteness and a highest positive indirect influence was gelatinization start temperature. Positive indirect influence was high revealed gelatinization start temperature and amylose content, negative indirect influence was whiteness and gelatinization start temperature. In RT storage of Multiple regression equation of Toyo index based on physicochemical properties of unhulled rice, a highest coefficient of determination was revealed among five facters of whiteness, protein content, Mg/K ratio, amylose content and gelatinization start temperature. In cool storage of Multiple regression equation of toyo index based on physicochemical properties of unhulled rice, highest coefficient of determination was revealed among five facters of moisture content, amylose content, gelatinization start temperature, breakdown and setback.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1281-1286
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• 2008

Nitrous oxide(N$_2$O) is well known as a greenhouse gas that contributes to the global warming (310 times more per molecule than carbon dioxide) and to the destruction of the ozone layer. The objective of this study is to estimate N$_2$O emission factor using an emission isolation flux chamber from municipal wastewater treatment plants. N$_2$O gas was analysed by GC/ECD with 6 port gas sampling valve. The results of this study were as follows. N$_2$O emission factor of 5-Stage process from Y wastewater treatment plants was lowest as 0.94 g-N$_2$O/kg-TN. And that of other processes were 2.65 g-N$_2$O/kg-TN for Activated sludge process, 9.30 g-N$_2$O/kg-TN for Denipho process, and 26.73 g-N$_2$O/kg-TN for Sequencing Batch Reactor process. We have known that 5-Stage process is most appropriate process to reduce greenhouse for municipal wastewater treatment plants.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.404-408
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• 2003

In this study, hydrogen gas produced by anaerobic mocrobial at anaerobic condition. To maintain the high MLSS concentration, anaerobic sludge was transformed to granular sluge by adding both high molecular cationic polymer(M.W>5,000,000) and silica sol. Hydrogen production was easily distributed, which seemed caused by methane producing microbial. Even low pH control(pH<5.5) was not the effective mean to block methane producing microbial. To decrease of $H_2$ production was closely related with the inclose of $CH_4$ production. Other mean expect for pH control must be devised for the efficient $H_2$ production.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.339-342
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• 2003

In this study , hydrogen gas produced by anaerobic mocrobial at anaerobic condition. To maintain the high MLSS concentration, anaerobic sludge was transformed to granular sluge by adding both high molecular cationic polymer(M.W.>5,000,000) and silica sol. Hydrogen production was easily distributed, which seemed caused by methane producing microbial. Even low pH control(pH<5.5) was not the effective mean to block methane producing microbial. To decrease of $H_2$ production was closely related with the inclose of $CH_4$ production. Other mean expect for pH control must be devised for the efficient $H_2$ production.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.1
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• pp.64-73
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• 1997

Most of the municipal wastewater treatment plants operated in Korea are designed for high concentrations municipal sewage. However, activated sludge process employed by municipal wastewater treatment plant is operated at low organic loading. The objective of this study was to determine optimum operating condition of activated sludge process for treatment of low concentration municipal sewage. Three bench scale activated sludge reactors were operated to investigate the effect of HRT and SRT on the COD and TSS removal efficiency. The average concentration of TSS, SCOD, SBOD and TKN in influent were 118mg/l, 61mg/l, 21mg/l, and 12mg/l, respectively. The activated sludge reactors operated with various HRT and SRT showed about 89-93% TSS removal efficiency. HRT and SRT does not affect the TSS removal efficiency of actvatied sludge process significantly. However, HRT affected the SCOD removal efficiency slightly. As the HRT decreases from 13hours to 3hours, the SCOD removal efficiency decreases from 67% to 56%. The average effluent TCOD concentration of the reactor operated with 3hours of HRT was approximatly 40-45mg/l. Kinetic coefficient yield (Yt) and decay coefficients(Kd) were 0.594-0.954 mgMLVSS/mgCOD and $0.0197-0.0317day^{-1}$, respectively. Low concentration municipal sewage can be treated with 3 hours of HRT without effluent quality deterioration and SRT does not affect the substrate removal efficiency at this operation condition.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.370-372
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• 2005

본 연구는 전자선을 이용하여 염색폐수에 함유되어 있는 난분해성 물질을 생물학적으로 분해가 용이한 물질로 전환시키는 한편 전환되어진 물질을 표준 활성슬러지법을 이용하여 생물학적 처리함으로 처리효율을 극대화 하는 전자선이용 염색폐수 정화기술을 개발하기위해 수행하였다. 종합 염색폐수에 1 kGy의 전자선 전처리를 한 후 생물학적 처리를 연계하였을 때 0.1 이상의 생분해도 증가를 나타냈으며 오염부하량 변화에 따른 미생물 활동도역시 안정적이었다. 또한 물벼룩을 이용한 생태독성 평가에서도 2.49의 원폐수 독성이 2.16이하로 감소함을 확인하였다. 난분해성 물질에 대한 전자선 전처리의 효과를 확인하기 위하여 대표적인 난분해성 물질인 TPA 인공폐수를 대상으로 전자선 가속기 전처리한 결과40 % 이상 처리효과를 얻을 수 있었다. 이러한 결과로 보아 전자선 전처리와 생물학적 처리공정의 연계로 보다 효과적인 염색폐수의 처리가 가능할 것으로 사료된다.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1119-1127
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• 2010

The behavior of copper throughout the whole process of wastewater treatment plant that uses the activated sludge process to treat the wastewater of petrochemical industry that contains low concentration of copper was investigated. Total inflow rate of wastewater that flows into the aeration tank was $697\;m^3$/day with 0.369 mg/L of copper concentration, that is, total copper influx was 257.2 g/day. The ranges of copper concentrations of the influent to the aeration tank and effluent from the one were 0.315 ~ 0.398 mg/L and 0.159 ~ 0.192 mg/L, respectively. The average removal rate of copper in the aeration tank was 50.8 %. The bioconcentration factor (BCF) of copper by microbes in the aeration tank was 3,320. The accumulated removal rate of copper throughout the activated sludge process was 71.3%, showing a high removal ratio by physical and chemical reactions in addition to biosorption by microbes. The concentration of copper in the solid dehydrated by filter press ranged from 74.8 mg/kg to 77.2 mg/kg and the concentration of copper by elution test of waste was 2.690 ~ 2.920 mg/L. It was judged that the copper concentration in dehydrated solid by bioconcentration could be managed with the control of that in the influent.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.1
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• pp.89-106
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• 1999

This research was undertaken to manage the waste treatment facility in cosmetic plants more effectively, The discharge and the treatment of pollutant in cosmetic plants were analyzed. And several factors which had an influential effect of the treatment cost, were found out. Effective management methods are proposed. Since average operating rate is estimated from 29% to 56%, the facility has an 44% to 71% surplus capacity. The pollutant removal rate influences highly on the treatment cost. The amount of MLSS is the factor that effects the removal rate. Chemical cost and the amount of the sludge are the influencing factors. To reduce the waste water treatment cost,-the saving of SV3O use and the management of MLSS amount are essential.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.67-78
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• 1997

The objective of study was to examine to transient response of hydraulic shock loading in activated sludge process for treatment of municipal sewage. The general experiment approach was to operate the system under steady-state(pre-shock), then to apply step changes during 24hours in fourfold hydraulic shock loading at the same organic loading. Performance was assessed in both the transient state and the new steady-state(post-shock). Three bench scale activated sludge reactors were operated to investigate the effect of fourfold hydraulic shock loading on TSS and COD removal efficiency. In activated sludge reactors operated with 13hours and 7hours of HRT, effluent quality of all reactors was not changed for few effects, and also showed no foaming and no sludge bulking. Those results are the same as sludge withdrawn reactors. The effect of fourfold hydraulic shock loading on the activated sludge reactors operated with 3hours of HRT was most severe. The effluent quality was deteriorated significantly and generate foaming in reactors. Less than 24hours after the fourfold shock loading applied, the activated sludge system seemed to attain a new steady-state condition as show by effluent.