• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1169-1180
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• 2013

The objectives of this study are to construct the natural streamflow in the Bokhacheon middle-upper watershed using the SWAT-K model and to assess the impacts of groundwater withdrawals, water intake, treated sewage water release on streamflow. The simulated natural streamflow from 2006 to 2013 showed the minimum discharge of $1.7m^3/s$, the annual average discharge of $26.2m^3/s$, the drought flow of $2.0m^3/s$ at the outlet of the study area. The simulated results indicated that the groundwater pumping has induced the decrease of 34% in drought flow against the natural condition and the net water release has caused the increase of 15%, while the combined effects of the groundwater pumping and the net water release have induced the decrease of 19%. It was found out from the simulated natural streamflow data that the specific discharges of the abundant flow, normal flow, low flow, drought flow in the upper-middle channels of the Bokha-cheon watershed have a tendency to increase as the drainage area increases, but the specific discharges showed almost constant values at any downstream point with drainage area more than about 180 $km^2$.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.362-369
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• 2019

In this study, biodegradation efficiency improvement of mixed sludge for the anaerobic digestion process in wastewater treatment plant was investigated. In order to release the organic material contained in the sludge cell and promote the hydrolysis step, mixed sludge of 7% TS (Total Solids) was physically shear-treated at a shear strength of 1,000 ~ 4,000 rpm and a maximum of 120 mins. As a result of the comparison between mixed sludge before and after the treatment, the concentration of $SCOD_{Cr}$(Soluble Chemical Oxygen Demand-chromium method) was increased through the conversion of granular organic matter into dissolved organic matter as shear strength and treatment time increases. The solubilization efficiency increased rapidly after 30 min of solubilization application time, and they were 11.23 %, 20.10 %, 22.52 % and 25.43% at 120 min for each shear strength conditions, respectively. Additionally, the BMP(Biochemical Methane Potential) test was conducted with the optimized samples to determine the increase of methane production by the shear pre-treatment. Consequently, methane production of each samples were 0.275, 0.310, 0.323 and $0.335m^3/kg\;VS_{add}$, which indicates that methane production was increased to a maximum of 21.28% compared to the control without the solubilization process ($0.262m^3/kg\;VS_{add}$). As a result, the physical shear-treatment is a promising process for sewage sludge pre-treatment to reduce the organic waste and increase the energy production.