• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.808-812
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• 2013

A new type of microbial fuel cell (MFC) with anaerobic membrane filter was designed to produce bioelectricity and to treat domestic sewage at relatively high organic loading rate (OLR) of $6.25kgCOD/m^3/day$ and short hydraulic retention time (HRT) of 1.9 h. A following aeration system was applied to ensure effluent water quality in continuous operation. Glucose was supplemented to increase the influent concentration of domestic sewage. Influent substrate of 95% was removed via the MFC and following aeration system and the corresponding maximum power density was $25.6mW/m^3$. External resistor of $200{\Omega}$ and air-cathode system contributed better MFC performance comparing to $2000{\Omega}$ and dissolved oxygen as a catholyte.

• Journal of Industrial Technology
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• v.2
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• pp.33-44
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• 1982

This study mainly concentrated on the treatment of nightsoil by an anaerobic filter media process. Nightsoil has been one of the major water pollutants in this couotry. It represents high ROD and SS concentrations. A comprehensive laboratory study conducted at Kangwoon National University indicate: (1) In the case of anaerobic filter system, COD and BOD removal efficiencies were greatly influenced by hydraulic retention time(HRT), but SS removal efficiencies dropped slowly when HRT were 2~13 days. (2) COD removal efficiencies were 19% when HRT were 15 days, 14% when HRT were 8 days, 10% when HRT were 6 days, 9% when HRT were 4 days, 2% when HRT were 2 days. (3) BOD removal efficiencies were 23% when HRT were 15 days, 14% when HRT were 8 days, 18% when HRT were 6 days, 7% when HRT were 4 days, 5.8% when HRT were 2days. (4) SS removal efficiencies were 21%~25%(2~15 days HRT).

• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.13-23
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• 2014

A lab-scale Anaerobic Baffled Reactor (ABR) was applied to treat a primary sludge taken from a municipal wastewater treatment plant. In this experiment, acidogenic reaction was promoted by operating the ABR with short hydraulic retention time (HRT) to produce sufficient volatile fatty acids (VFA) instead of production of methane. The performance of ABR on the VFA production and total solids reduction was observed with different operating conditions with 2, 4, 6, and 8 days of HRT. Corresponding organic loading rates were 6.7, 3.4, 2.2, and $1.6kgCOD_{cr}/m^3{\cdot}day$. As HRT increased the removal rate of TCOD was also increased (82.5, 84.2, 96.9, and 95.9 % in average for HRT of 2, 4, 6, and 8 days, respectively) because the settlement of solids was enhanced in the baffle by the decrease of upflow velocity. At HRT of 2 days the average concentration of VFA in the effluent was measured at $1,306{\pm}552$ mgCOD/L corresponding to 107 % increment as compared to the VFA concentration in the influent. However, as HRT increased VFA concentraiotn was decreased to $143{\pm}552$ mgCOD/L at HRT of 8 days. The reduction rates of total solids were 12.2, 26.5, 24.8, and 43.0 % for HRT of 2, 4, 6, and 8 days. As HRT increased the hydrolysis of organic particulate matters in the reactor was enhanced due to the increasing of solids retention time in the baffle zone with low upflow velocity in long HRT condition. Consequently, we found that a primary sludge became a good source of VFA production by the application of ABR process with HRT less than 4 days and the 12-26 % of total solids reduction was expected at these conditions.

• Journal of environmental and Sanitary engineering
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• v.9 no.1
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• pp.29-37
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• 1994

Anaerobic treatment of wastewater of the red- bean processing industry was carried out and discussed an anaerobic sludge bed reactor( ASBR) as a preliminary study to evaluate applicability of given processes. The dimension of reactor were same as 0.09m- ID$\times $1.5m- height. The type of substrate and the hydraulic retention time( HRT) were considered as experimental variables. The synthetic wastewater with glucose in the laboratory, the wastewater from the red bean processing industry mixed with synthetic wastewater with variation of mixing percent were fed as substrate. The hydraulic retention time was changed from one day to five days. The gas production, the methane content in produced gas, efficiencies of COD removal and 55 removal were evaluated as principal characteristics. With synthetic wastewater as a substrate and at a hydraulic retention time of one day, characteristics of ASBR was the gas production(12$\ell$/day ), the methane content of produced gas(60%), the efficiency of COD removal(92%) and 55 removal(30%). With the real wastewater and at a hydraulic retention time of one day, the gas production and the efficiency of COD removal of the ASBR decreased with the proportion of real wastewater. The gas production and the efficiency of COD removal with real wastewater only was decreased to 70% and 87% of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. With real wastewater only as a substrate in the ASBR, the gas production was decreased with an increase of HRT, but the efficiency of COD removal increased with HRTI like the usual trend reported. As a conclusion, the wastewater of the red- bean Processing industry could be treated by anaerobic digestion successfully in the ASBR.Anaerobic treatment of wastewater of the red- bean processing industry was carried out and discussed an anaerobic sludge bed reactor( ASBR) as a preliminary study to evaluate applicability of given processes. The dimension of reactor were same as 0.09m- ID$\times $1.5m- height. The type of substrate and the hydraulic retention time( HRT) were considered as experimental variables. The synthetic wastewater with glucose in the laboratory, the wastewater from the red bean processing industry mixed with synthetic wastewater with variation of mixing percent were fed as substrate. The hydraulic retention time was changed from one day to five days. The gas production, the methane content in produced gas, efficiencies of COD removal and 55 removal were evaluated as principal characteristics. With synthetic wastewater as a substrate and at a hydraulic retention time of one day, characteristics of ASBR was the gas production(12$\ell$/day ), the methane content of produced gas(60%), the efficiency of COD removal(92%) and 55 removal(30%). With the real wastewater and at a hydraulic retention time of one day, the gas production and the efficiency of COD removal of the ASBR decreased with the proportion of real wastewater. The gas production and the efficiency of COD removal with real wastewater only was decreased to 70% and 87% of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. With real wastewater only as a substrate in the ASBR, the gas production was decreased with an increase of HRT, but the efficiency of COD removal increased with HRTI like the usual trend reported. As a conclusion, the wastewater of the red- bean Processing industry could be treated by anaerobic digestion successfully in the ASBR.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.489-494
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• 2013

Effects of operating parameters such as hydraulic retention time(HRT), recycle ratio and influent COD concentration on the performance of a continuous flow microbial fuel cell(MFC) were investigated. Decrease of HRT improved mass transfer of substrate to electrogenic microorganisms, therefore resulting in increased electrode voltage and power generation of MFC. Increase of HRT promoted COD removal by elongating retention time for COD removal in MFC. Recycling of effluent increased the COD removal and coulombic efficiencies by returning suspended microorganisms into MFC. Increase of influent COD enhanced COD removal due to the improved mass transfer of substrate. Decrease of coulombic efficiency by the increase of the HRT and influent COD concentration indicated that they enhanced the activities of fermentative bacteria.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.1
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• pp.78-84
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• 1996

The presence of ammonia, usually in the form of ammonium ion ($NH_4{^+}$), can enhance bacterial growth m the distribution system and make the production of drinking water more costly if ammonium must be removed to ensure good disinfection. Removal of ammonia by biological oxidation could be economical which prevents excess chlorine dosage In this research, effects of hydraulic retention time (HRT) and media type on the ammonia removal efficiencies of submerged biofilm reactor were investigated. The biofilm reactors combined the characteristics of high biological solids capture efficiency and good hydraulic control. The results indicate that biofilms can remove over 77 percent of the ammonia with HRT of longer than 2 hr even at low temperature ranging from 14.6 to $16.6^{\circ}C$. The HRT has a significant effect on nitrification. The overall nitrification and efficiency of ammonia removal increase with increasing HRT. It has also been observed that when the fibrous media was used, the ammonia removal, nitrification rate and endurance to shock improved.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.121-128
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• 2012

The purpose of this study is to solve the problem of nutrient removal due to rapid hydraulic retention time (HRT) variation in small size private sewage treatment facility and to have better effluent quality by using natural zeolite as a coagulant aid. The experiments were conducted by applying different conditions of HRT, coagulant, and zeolite dosages. As an experimental result, $TBOD_{5}$, TSS, and TP removal efficiencies were 64.9%, 94.5%, and 98.8% at co-injection with zeolite. Overall removal efficiencies of $TBOD_{5}$, TSS, and TP have improved 15.7, 28.7, 6.1%, respectively. This result shows that zeolite addition could improve flocculation, increase setting velocity, and thus have better treatment. Therefore the use of zeolite as a coagulant aid can be useful in small size private sewage treatment facility, where especially extra nutrient removal is required to meet the legal standard for discharge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.117-127
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• 1983

An experimental research was performed employing the two stage anaerobic digestion of the mixture of the nightsoil and septic tank sludge to determine the effects of various hydraulic retention time of the digestion on chemical characteristics and treatment effeciency, thus determining the proper retention time. Results of the research are as follows, 1. Volatile-acid decreased as HRT increased. 2. Alklinity and ammonia-N tended to increase as HRT increased as did pH values, however, were observed to be constant at higher HRT values than 15 days. 3. The removal efficiencies of TBOD, TCOD and VS increased as HRT increased. 4. The removal efficiency of volatile solid decreased as VS loading increased. 5. It was observed that the rates of gas production were: 0.33 with HRT of 5 days, 0.58 with HRT of 15 days and $0.57m^3/kg$ VS fed/day with HRT of 25 days respectively. It is believed that the highest rate of gas production was at HRT of 15 days. 6. The sludge settling experiment showed that the minimum settling time required to ensure the desired underflow concentraton was estimated to be 8.6 days.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.865-872
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• 2009

Continuous operation of aerobic sludge digestion reactor was attempted for 279 days. Anaerobic digester sludge, the target material of the experiment, was pretreated by sodium hydroxide at $40^{\circ}C$ for 120 minutes, and the pretreated sludge was fed to 5 L CSTR (continuous stirred tank reactor). Reactor performance was affected by properties of input sludge and HRT (hydraulic retention time). 6 days of HRT showed best and stable performance, and under this condition, removal rates of $NH_3$-N, SCOD, TKN, TCOD, SS, and VSS were 97.4%, 81.7%, 68.7%, 61.4%, 50.6%, and 47.0%, respectively. 73.9% of SS in anaerobic digester sludge was reduced by pretreatment and aerobic digestion. Effluent sludge had low soluble COD of 350 mg/L. This implied the sludge was stabilized and suitable for use as liquid fertilizer. Nitrification took place when HRT was higher than 4 days. $NO_3$-N concentration was as high as 658 mg/L while $NH_3$-N was as low as 20 mg/L.

• Journal of Aquaculture
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• v.16 no.4
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• pp.252-256
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• 2003

Effluent from farm trefish contained high concentrations of nitrogen and phosphorus, such kinds of nutrients were released to the environment without proper treatment and thses increased the pollution of the environment. We evaluated the conventional treatment system with cost effective ecotechnologies for the removal of nutrients. Water lettuce chambers were investigated under the various experimental conditions to improve the efficiency of N&P removal and the treatment of from aquaculture effluent. In this research, six water lettuce chambers (80 liter each) received combination of aquaculture wastewater effluent at hydraulic retention times (HRTs) of 1, 2, 4 and 8days. The water lettuce chambers operated at a 8 day HRT investigated for aquaculture effluent (1'st) showed average removal efficiency, BOD, T-N, T-P of 92.8, 79.0 and 93.6% on average respectively.