• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.483-490
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• 2014

The design procedures for a biological reactor and a secondary settling tank (SST) of an activated sludge system are based on the steady state design method (Ekama et al., 1986; WRC, 1984) and the 1-D flux theory design method (Ekama et al., 1997), respectively. This study combined both of the design procedures, to determine the optimum sludge concentration in the reactor and the best design with the lowest cost. The best design of the reactor volume and the SST diameter at the optimum sludge concentration were specified with varying wastewater and sludge characteristics, temperature, sludge retention time (SRT) and peak flow rate. The effects of the influent wastewater characteristics, such as substrate concentration and unbiodegradable particulate fraction, were found to be considerable, but the effect of unbiodegradable soluble fraction was to be negligible. The effects of sludge settling characteristics, were also significant. SRT, as an operating parameter, was found to be an important factor for determining the optimum sludge concentration. However, the effect of temperature was found to be small. Furthermore, for designing a large scale wastewater treatment plant, the number of reactors or SSTs could be estimated, by dividing the total reactor volume or SST area. The new combined design procedure, proposed in this research, will be able to allow engineers to provide the best design of an activated sludge system with the lowest cost.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.90-96
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• 2020

This paper aims to reuse sewage by a forward osmosis using a blended fertilizer as a draw solution. This work deals with the primary sedimentation basin influent, effluent, and secondary sedimentation basin effluent from J sewage treatment plant. The average permeate water flux was higher in the order of the blend of KCl and NH₄Cl > KCl and NH₄H₂PO₄ > KCl and (NH₄)₂HPO₄, and the reverse solute flux was lower in the order of the blend of KCl and NH₄H₂PO₄ < KCl and NH₄Cl < KCl and (NH₄)₂HPO₄. Regardless of the blended fertilizer, the permeate water flux of the effluent from the secondary sedimentation basin was the highest. The blended fertilizer of KCl and NH₄H₂PO₄ was found to be most useful for the reuse of sewage because it contains nitrogen, phosphorus and potassium, which are the major components of a fertilizer, and has a low reverse solute flux. When the blend of KCl and NH₄H₂PO₄ was used as a draw solution, the average permeate water and reverse solute flux for the secondary sedimentation basin effluent were 12.14 L/㎡hr and 0.012 mol/㎡s, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.363-369
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• 2009

In order to evaluate primary clarifier performance on TSS(Total Suspended solids) removal, four different sampling sets were collected as part of this study; (1) weekly test, (2) the diurnal sampling, (3) the settling velocity distribution sampling. Primary effluent TSS($TSS_{PE}$) and non settleable TSS($TSS_{NON}$) concentrations were averaged 160 and 75.5 mg/L, respectively. These data suggest approximately 85 mg/L TSS can be removed more. Average $TSS_{NON}$, $TSS_{PE}$, and Dispersed TSS(DTSS) concentrations(75.5, 160, and 104 mg/L, respectively) suggest that 28.5 mg/L of TSS difference attributable to poor flocculation, whereas 56 mg/L of TSS difference attributable to poor hydraulics within primary clarifier. In this study, equations for maximum TSS removal efficiency and effluent TSS concentration were suggested and compared with experimented data.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.375-379
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• 2007

폐비닐 여재(Synthetic Waste Polyethylene Media)를 적용한 부착성장식 공정의 유기물 및 질소${\cdot}$인 제거특성에 관한 Pilot Plant 실험 결과 다음과 같은 결론을 얻을 수 있었다. 1) 제거효율은 $RUNI1{\sim}3$에서 $COD_{cr}$ 91.4, 92.4, 93.9%, T-N 56.9, 61.4, 65.1%, T-P는 모든 단계에서 약 45%이상 제거되어 부하변동시에 강한 대처능력을 나타내었다. 2) BOD용적부하 $0.18{\sim}0.40kg/m^3{\cdot}d$, COD용적부하 $0.28{\sim}0.53kg/m^3{\cdot}d$, ${NH_4}^{+}-N$용적부하 $0.12kg/m^3{\cdot}d$을 나타내었다. 3) 도시하수 처리를 위한 생물학적 질소 및 인 제거공법을 본 여재를 이용하여 공정설계시 고려할 사항들과 적절한 대처방법을 다음과 같이 제시할 수 있다. - 1차 침전지에서 유기질소 및 유기인 농도가 높다면 유기질소 및 인 부하량을 감소시키기 위하여 1차 침전지를 설치하되 질소 및 인제거에 유리한 $BOD_5/T-N$, $BOD_5/T-P$를 유지할 수 있도록 체류시간을 1시간미만으로 설계하는 것이 경제적이라고 판단된다. 만일 유기질소와 유기인의 함량이 낮다면 1차 침전지는 제외하는 것이 유리할 것이다. - 여재의 배치는 폭기조에서 용존산소의 균일분포와 슬러지의 적정탈리를 위해 여재를 상하로 배치하거나 또는 여재끼리 일정 간격을 두어 배치하는 것이 바람직하다. 농촌에서의 처분이 문제시 되고 있는 폐비닐을 적용한 본 연구에서의 수처리특성은 기존 하수처리공정에서의 제거효율에 상응하는 처리특성을 나타내었다. 또한 폐비닐 처분의 문제를 해결할 수 있을뿐만 아니라 하수처리시에도 부하변동 등에 강한 대처능력을 나타내어 기존의 하수처리공정에 대체가능성을 나타내었다.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.122-131
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• 2019

In order to reuse and concentrate the sewage, a forward osmosis using fertilizer as draw solution was applied. Sewage-1, which is the supernatant after settling for 30 minutes for the primary settling basin influent, and Sewage-2, which is the supernatant after settling for 30 minutes for the effluent, and Sewage-3, which is the filtrate filtered through a $1{\mu}m$ cartridge filter for the effluent were tested. Eight draw solutions of $NH_4H_2PO_4$, KCl, $KNO_3$, $NH_4Cl$, $(NH_4)_2HPO_4$, $NH_4NO_3$, $NH_4HCO_3$, and $KHCO_3$ were used in consideration of osmotic pressure, solubility and pH. In the case of Sewage-3, the permeate flux was almost similar to that of the discharge water of the sewage treatment plant, and was larger than that of Sewage-1 and Sewage-2. $NH_4H_2PO_4$ was the smallest, and $NH_4NO_3$ was the largest in the specific reverse solute flux. $NH_4H_2PO_4$ was found to be most useful for the reuse and concentration of sewage because it contains nitrogen and phosphorus, which are the major components of fertilizer, as well as low specific reverse solute flux. When $NH_4H_2PO_4$ was used as the draw solution, the concentration factor after 24 hours for Sewage-3 was 1.72.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.213-220
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• 2002

This reserch was focused upon experimental study for wastewater reuse and conducted to evaluate optimum operating conditions of rapid filtration process such as filter flow rate, filtration time and backwashing condition for reuse of secondary-treated effluent using the pilot plant installed in real wastewater treatment plant. Also, the experiment on treatment char-acteristics of coagulant-added activated sludge process was performed to compare with activated sludge succeeded to rapid filtration. As the filtration velocity was 100m/day, the filtration time of the rapid filter connected with activated sludge system was revealed to 40 hours. Backwashing of filter was conducted by water wash and air scour. The optimum backwashing time and backwash flow rate were 10min and 10LPM, respectively. The quantity of backwashing water of the rapid filter was about 2% of total treated water.

• Membrane Journal
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• v.26 no.2
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• pp.108-115
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• 2016

This study is to evaluate the performance of draw solutions in the water reuse of sewage discharge water using fertilizer drawn forward osmosis. Feed water used in all experiments was the effluent from secondary sedimentation tank in activated sludge process. Considering osmotic pressure, solubility, and pH, $NH_4H_2PO_4$, KCl, $KNO_3$, $NH_4Cl$, $(NH_4)_2HPO_4$, $NH_4NO_3$, $NH_4HCO_3$, and $KHCO_3$ were screened from a comprehensive lists of fertilizer. Their performances were evaluated in terms of water permeate flux and reverse solute flux. KCl showed the highest average water flux followed by $NH_4Cl$, $NH_4NO_3$, $KNO_3$, $KHCO_3$, $NH_4HCO_3$, $NH_4H_2PO_4$, and $(NH_4)_2HPO_4$. Using KCl as draw solution, the average water permeate flux was 13.49 LMH. There was no big difference in osmotic pressure between the effluent from secondary sedimentation tank and deionized water. $NH_4H_2PO_4$ showed the lowest reverse solute flux followed by $NH_4Cl$, $(NH_4)_2HPO_4$, $KNO_3$, $NH_4HCO_3$, and $NH_4NO_3$. Using $NH_4H_2PO_4$ as draw solution, the reverse solute flux was $4.96{\times}10^{-3}mmol/m^2{\cdot}sec$.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.549-556
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• 2012

T-P removal efficiency was analyzed according to the metal to initial T-P ratio (mole basis) with respect to the samples from different WWTPs having various initial T-P and SS conditions. Also, operating costs were calculated based on the injected coagulant amount and the amount of sludge production. Most experiments were conducted by the standard jar-test protocol. Molar ratio of coagulant dose was varied considerably according to the initial SS concentration range in secondary clarifier effluent samples which had above 0.5 mg/L of initial T-P. Based on 90% T-P removal efficiency, results were: At the initial SS range of below 10 mg/L, Alum (8%) = 11 mol Al/mol P needed and PAC (17%) = 9.6 mol Al/mol P needed; At the initial SS range of above 10 mg/L, Alum (8%) = 3.9 mol Al/mol P needed and PAC (17%) = 3.2 mol Al/mol P needed.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.53-65
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• 2012

This study was focused on removal efficiency of complex (or mixed) wastewater from agricultural and industrial plant for advanced treatments by HBR-II process, that was well known to be suitable to the treatment of livestock wastewater. The main purpose of this study was intended to evaluate the applicable feasibility of the HBR-II for revamping the present activated sludge process to the advanced one. And also, the settling study including the batch typed experimental column tests was performed to evaluate the coagulation stability of organic colloidal particles in wastewater. The mid-scale plant of HBR-II process between pilot and laboratory was used for this study. As F/M ratio remains constant in the range of 0.20~0.25 $BOD_5/Kg{\cdot}MLSS/Day$, the efficiency of biological treatment increased. It has been shown that the results of biodegradation study were, for removal efficiency(%), $BOD_5$ 98.4%, $COD_{Mn}$ 92.9%, SS 97.5%, T-N 91.3%, T-P 82.3%, respectively, which were relatively higher than other processes. From this study, HBR-II process would be well applied to the biological treatment of agricultural and industrial complex wastewater.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.73-80
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• 2018

In this study, the solids removal characteristics using T-P sludge generated from PACl coagulation were analyzed by laboratory scale and full scale experiment. As the amounts of T-P sludge injection into the raw sewage influent increased at the rate of 0, 1, 2, 3, 4 %, the suspended solids concentrations after 20 minutes setting test decreased to 210, 137, 91, 64, 43 mg/L, respectively. The filtration time required for dewatering test of the raw sewage influent decreased to 982, 728, 658, 581, 492 sec for 0, 1, 2, 3, 4% of T-P sludge injection, respectively. As the amounts of PACl coagulant into the effluent from final setting tank increased at 0, 10, 20, 30, 40 mg/L, the required filtration times for T-P sludge increased into 12.3, 41.7, 53.7, 67.2, 79.5 sec and the dewaterability of T-P sludge decreased. After T-P sludge returned into the primary settling tank on J-si sewage treatment plants, the effluent concentrations of COD, SS, T-N and T-P from primary settling tank into bioreactor decreased by 35.9, 27.9, 22.2, and 52.6% due to the coagulation effects of the T-P sludge. Finally, it was found that the return of T-P sludge into the primary settling tank could result into the sludge reduction having a lower water content of 3.03% p than in case of the only T-P sludge dehydration.