• Membrane Journal
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• v.26 no.1
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• pp.70-75
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• 2016

The reuse of wastewater is being diffused to manage and develop the water resources. Generally, the treated wastewater is discharged to the river after being treated to meet the effluent quality standard or reused for diverse uses through the reprocessing. And recently, as the reuse of the treated wastewater is activated, the technologies to utilize for the high quality water resources such as industrial water by reusing the wastewater with Membrane Distillation (MD) are under development. In this study, the direct contact membrane distillation (DCMD) process has been applied to treat sewage discharge water for water reuse. The laboratory scale experiment was performed by using a hydrophobic PVDF membrane with the pore size of $0.22{\mu}m$. The influence of operating parameters, such as feed temperature, feed flow rate, feed concentration, on the permeate flux and rejection has been investigated. All filtration tests were conducted till the feed volume reached a concentration factor of 3.0. Thus, the operating period ranged between 19 hr and 49 hr depending on filtration performance. The results showed that above 92% of TN, TP, COD and TOC in the feed could be rejected regardless of an operating condition. The water flux was ranged from 13.8 to 20.3 LMH. The lowest flux was obtained at the operating condition with the feed temperature of $50^{\circ}C$ and feed flow velocity of 500 mL/min while the highest one was measured with $60^{\circ}C$ and 900 mL/min. When the concentration factor reached 3.0, water flux declined by approximately ranged from 14.5% to 33.3%. But the fouling in MD is almost fully reversible, with more than 90% recovery of permeate water flux following a DI water rinse without the addition of chemical cleaning reagents.

• 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 $4.96{\times}10^{-3}mmol/m^2{\cdot}sec$.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.259-262
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• 2003

Surveyed effluent capacities for potential wastewater resources through the surveying of the sewage treatment plants its capacity is up to 10,000 tonnes per day located 4 provinces (kyunggi, gangwon, chungbuk, chungnam) in this year. The total effluent capacities in this provinces are 423 thousand $m^3/day$, which may be used to irrigated paddy fields of 2,310ha A GIS database for wastewater resource inventory was developed for 4 provinces (kyunggi, gangwon, chungbuk, chungnam) to explore the feasibility of the wastewater reuse for drought mitigation. And it is to be extended to the other wastewater treatment plants.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.59-65
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• 2011

The purpose of this study was to analyze the water quality change when wastewater applied to study paddy fields. CREAMS-PADDY (Chemical, Runoff and Erosion from Agricultural Management System) model was used to estimate the field-scale water quality. Simulated results were compared with observed data monitored from Byeongjeom study paddy fields which is located near the Suwon sewage treatment plant in Gyeonggi-do. Significance analysis was performed for the three different irrigation water quality level and five fertilizer reduction scenarios using LSD (Least Significant Difference) and DMRT (Duncan's Multiple Range Test). Total nitrogen was found to be significant for both irrigation water quality level and fertilizer reduction while total phosphorus was not. Annual drainage load for total nitrogen was reduced by 66~92 % compared to irrigation load when treated wastewater irrigated to study paddy fields from 2002 to 2007. Total phosphorus was reduced by 70~86 %.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.81-87
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• 2008

We have investigated the efficacy and efficiency of the used briquets for the sewage treatment in this study. The effluent of wastewater treated by Used Briquets Process (UBP) showed very low values of $BOD_5$, CODcr, and SS (1.1 mg/L, 9.5 mg/L, and 3.8mg/L, respectively), which corresponded to 99%, 92.7%, and 96.3% of removal efficiency to the raw wastewater. The number of total bacteria and E. coli in the effluent water treated by UBP was found to be 9 and 1.2 cfu/ml, respectively, showing the remarkable decrease in number, when compared to that of other sewage treatment plants. In the long period of experiment over 1 year, UBP has also shown the high removal efficiency with less sludge production, and low seasonal fluctuation of the values. This UBP is very environmentally-friendly process in the aspects of recycling used briquets and reducing the sludge production. We think that this process will be useful for both the small-scale sewage treatment and reuse of the effluent water.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.35-43
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• 2003

In this study, the physical and chemical characteristics of incinerated pulp and sewage sludge ashes for recycling and reuse were examined. Then we studied the application to the cement admixture by pozzolanic reaction. The particle size of incinerated pulp and sewage sludge ashes was distributed around $10{\sim}100{\mu}$, and the contents of $SiO_2$ and $Al_2O_3$ were 45.8~51.0%, respectively. Compressive strengths of the solidified ashes were relatively higher, when the content of substituted incineration ashes was 10% and the porosity was also lower except for the case of sewage sludge ash. As results, it is shown that it may be possible to recycle incinerated pulp sludge ashes as cement admixtures.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.63-72
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• 2017

For economic evaluation of integrated operation to sewage facilities, benefit-cost analysis was performed to watershed sewage works project in 7 watershed areas, 156 facilities. In this study, the cost before and after integrated operation was compared and benefits are calculated from the reduction of operators, increasement treated pollution loads, reduction cost through operation convenience, reduction water consumption through effluent reuse, and improvement of life benefit. The result showed that cost was 8,500million won and benefit was 16,747million won, so benefit was 49% higher than cost. B/C analysis result showed that B/C ratio was 1.97 and it is similar to other researches. The benefits of integrated operation included convenience of data management, increase of emergency response, decrease of complains with sewage which was not reflected numerically, so the benefits of integrated operation were expected much greater than this result

• 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.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.344-354
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• 2004

A pilot study was performed from September 2000 to April 2004 to examine the feasibility of the wetland-pond system for the agricultural reuse of reclaimed water. The wetland system was a subsurface flow type, with a hydraulic residence time of 3.5 days, and the subsequent pond was 8 $m^3$ in volume (2 m ${\times}$ 2 m ${\times}$ 2 m) and operated with intermittent-discharge and continuous flow types. The wetland system was effective in treating the sewage; median removal efficiencies of $BOD_5$ and TSS were above 70.0%, with mean effluent concentrations of 27.1 and 16.8 mg $L^{-1}$, respectively, for these constituents. However, they did often exceed the effluent water quality standards of 20 mg $L^{-1}$. Removal of T-N and T-P was relatively less effective and mean effluent concentrations were approximately 103.2 and 7.2 mg $L^{-1}$, respectively. The wetland system demonstrated high removal rate (92 ${\sim}$ 90%) of microorganisms, but effluent concentrations were in the range of 300 ${\sim}$ 16,000 MPN 100 $mL^{-1}$ which is still high for agricultural reuse. The subsequent pond system provided further treatment of the wetland effluent, and especially additional microorganisms removal in addition to wetland-pond system could reduce the mean concentration to 1,000 MPN 100 $mL^{-1}$ from about $10^5$ MPN 100 $mL^{-1}$ of wetland influent. Other parameters in the pond system showed seasonal variation, and the upper layer of the pond water column became remarkably clear immediately after ice melt. Overall, the wetland system was found to be adequate for treating sewage with stable removal efficiency, and the subsequent pond was effective for further polishing. This study concerned agricultural reuse of reclaimed water using natural systems. Considering stable performance and effective removal of bacterial indicators as well as other water quality parameters, low maintenance, and cost-effectiveness, wetland- pond system was thought to be an effective and feasible alternative for agricultural reuse of reclaimed water in rural area.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.2
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• pp.285-294
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• 2012

Current urban stream conditions and their restoration projects were investigated by surveying the urban stream management experts in 29 cities with high population density (more than 1,000person/$km^{2}$). The survey results showed that the ratio of covered urban streams decreased by 1.4% (from 14% to 12.6%) in the last 5 years through steady river restoration projects promoted by governments. Nonetheless, 36.3% of 369 urban streams surveyed still report stream depletion problems; therefore, more efforts to alleviate the problems caused by distorted water circulation of urban streams are still necessary. Water depletion in many local urban streams, unlike national rivers, is accelerated due to negligence in stream management, budget shortage, and other reasons. To prevent stream depletion, the use of reclaimed water is suggested as one of the prevention plans. When available amounts of reused sewage are estimated through actual available nationwide sewage discharges of each watershed and instream flow of stream, annual instream flow supply of 780 million $m^{3}$ is expected; 4.8% reduction in the pollution load of public sewer treatment facilities is expected; and the creation of new value through water reuse service is expected. Thus, it is important for the reviews of feasibility and alternatives of water reuse projects for flow augmentation to consider not only investment budget reductions, but also environmental aspects. Also it is necessary to provide the financial support of unified government with strict water quality management policy.