• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.5
• /
• pp.557-564
• /
• 2009

A combined sewer system can quickly drain both storm water and sewage, improve the living environment and resolve flood measures. A combined sewer system is much superior to separate sewer system in reduction of the non-point source pollutant load. However, during rainfall. it is impossible in time, space and economic terms to cope with the entire volume of storm water. A sewage system that exceeds the capacity of the sewer facilities drain into the river mixed with storm-water. In addition, high concentration of CSOs by first-flush increase pollution load and reduce treatment efficiency in sewage treatment plant. The aim of this study was to develope a processing unit for the removal of high CSOs concentrations in relation to water quality during rainfall events in a combined sewer. The most suitable operational design for processing facilities under various conditions was also determined. With a designed discharge of 19.89 m/min, the removal efficiency was good, without excessive overflow, but it was less effective in relation to underflow, and decreased with decreasing particle size and specific gravity. It was necessary to lessen radius of vortex separator for increasing inlet velocity in optimum range for efficient performance, and removal efficiency was considered to high because of rotation increases through enlargement of comparing height of vortex separator in diameter. By distribution of influent particle size, the actual turbulent flow and experimental results was a little different from the theoretical removal efficiency due to turbulent effect in device.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.7
• /
• pp.746-751
• /
• 2006

In this study, drying and carbonization experiment was conducted in a fluidized bed reactor according to the variations in gas velocity, particle size, and reactor temperature. As a result, the weight loss rates of sludge by drying in the fixed bed and fluidized bed type dryer showed that drying in the fluidized bed was about 6 times faster than drying in the fixed bed, and the weight loss rates of sludge by carbonization in the fixed bed and fluidized bed type reactor showed that carbonization in the fluidized bed was about 4 times faster than drying in the fixed bed. This implies that carbonization in the fluidized bed was completed within 10 minutes. Although the amount of char decreased with the increase of carboniration temperature, the amount of char became similar at upper 873K. Also, the amount of char decreased with increasing gas velocity. Consequently, it could be efficient that slow fluidization should be maintained within the range of fluidization in case of fluidized carbonization of sewage sludge at 873K.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.11 no.2
• /
• pp.82-91
• /
• 2006

We investigated the possibility of using effluents from a municipal sewage treatment plant (STP) as tracers a tracer for hydrologic studies of rivers. The possibility was checked in a 12-km long reach downstream of Jeonju Municipal Sewage Treatment Plant (JSTP). Time-series monitoring of the water chemistry reveals that chemical compositions of the effluent from the JSTP are fluctuating within a relatively wide range during the sampling period. In addition, the signals from the plant were observed at the downstream stations consecutively with increasing time lags, especially in concentrations of the conservative chemical parameters (concentrations f3r chloride and sulfate, total concentration of major cations, and electric conductivity). Based on this observation, we could estimate the stream flow (Q), velocity (v), and dispersion coefficient (D). A 1-D nonreactive solute-transport model with automated optimization schemes was used for this study. The values of Q, v, and D estimated from this study varied from 6.4 to $9.0m^3/sec$ (at the downstream end of the reach), from 0.06 to 0.10 m/sec, and from 0.7 to $6.4m^2/sec$, respectively. The results show that the effluent from a large-scaled municipal STP frequently provides good, multiple natural tracers far hydrologic studies.

• Clean Technology
• /
• v.6 no.1
• /
• pp.39-49
• /
• 2000

Ultra Rapid Coagulation (URC) can dramatically remove pollutants loaded in wastewater by adding weighted coagulation additives (WCA) and recycling sludge into the coagulation basin to increase settling velocity and surface adsorption ability of floc. Also settling chamber together with lamella plates offers the high rate settling velocity, which can economically treat a considerable amount of pollutants like as combined sewage overflow (CSO) during the heavy rainfall and reduce the pollutants load into the receiving water for securing water source. It was estimated optimal configuration of settling chamber by using fluent model and the possibilities of reusing the sludge generated in this system.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1128-1133
• /
• 2008

Drying process in the thin film layer of sludge with the thickness less than a few millimeters has been investigated using the simple one-dimensional model. Thin film drying is usually used to dry the viscous materials like sewage sludge. The thin film layer of sludge is dried on the metallic surface through which thermal energy is supplied to the layer during drying. In order to solve the equations, the mass transfer rate on the drying surface should be determined. The mass flux of evaporated water vapor on the surface is estimated with the formulation given in the literature. The effect of heating temperature, film thickness, and air velocity on drying has been examined to figure out the drying characteristics of the sludge layer.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.133-138
• /
• 2001

In this paper, we have investigated the drying characteristics of waste sludge in a rotary dryer equipped with disintegration device. The sludge samples($moisture\;contents\;:\;70{\sim}85%\;W.B.$) used in the experiment were mainly a soybean and an alcohol fermentation sludges in food industry, or sewage sludge. It was studied by measuring the change of moisture contents that the shaft speed($operating\;range\;:\;100{\sim}250rpm$) affected on the drying rate and the particle size distribution of the dried solid. The dried granular products of the diameter of 1 to 5mm are obtained from sludge materials. In the results, as the increased of shaft speed, the particle size and the moisture contents of dried solid was decreased, and the retention time was increased.

• Journal of Power System Engineering
• /
• v.10 no.4
• /
• pp.105-110
• /
• 2006

Among many other alternative energy resources, small scale hydro power has been brought into attention as a reliable source of energy today, which had been relatively neglected since 1960s. Especially, Kaplan micro-turbine can be applied to various kind of small hydro power plants, such as reservoirs for agriculture purpose, sewage treatment plants and water purification plants. However present low head of Kaplan micro-turbines and small scale hydro turbines, have limitations in the minimum required head and flow rate for efficient operation. This research is to develop modeling analysis for the Kaplan micro-turbine, which can improve economical features of small hydro power plants. The contents and scope of this research are the efficiency improvement of Kaplan micro-turbine.

• Journal of Korean Society on Water Environment
• /
• v.28 no.4
• /
• pp.505-511
• /
• 2012

While the existing sewage treatment facilities are mainly being operated by biological processes, winter-time efficiency improvement and additional phosphorus treatment equipment using chemicals have been required to follow the effluent criteria of TP (0.2, 0.3 and 0.5 mg/L for the zone of I, II and III respectively) and $BOD_5$ (5.0 mg/L) which is intensified from 2012 in Republic of Korea. We made an investigation into actual condition of biological treatment process and calculated the optimal chemical input amount by jar test of supernatant of secondary sedimentation tank to evaluate the process improvement for the intensified criteria. Ejector BAF system for removing TP, $BOD_5$ of sewage effluent was suggested. The concentration of TP from biological process is 0.3-0.8 mg/L, and the input amount of optimal chemical coagulant was above Al/P ratio of 3(1.9 mg/L as Al) to meet the criteria of TP for secondary treatment effluent. From the results of this experiment, the best Al/P ratio for Ejector BAF system was about Al/P ratio of 1, and LV of BAF process for intensified criteria of $BOD_5$ and TP was below 1.97m/hr.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.11 no.2
• /
• pp.125-131
• /
• 2003

This study was carried out to develop INSUB(Indirected Aerated Submerged Biofilter) which can remove organics, nitrogen and phosphorus with an advanced treatment system. The results were as followed in laboratory model experiment. As for treatment of sewage, when economical efficiency was considered in practice, the highest removal efficiency was at 18hr of HRT, 1.017m/hr of superficial velocity and 40% of media packing ratio. Each removal efficiency for $COD_{cr}$, $COD_{Mn}$, $BOD_5$, T-N, and T-P was 90.6, 85.3, 95.0, 52.3 and 56.8%. To remove the nitrogen and phosphorus With high efficiency, first of all, denitrification have to be completed, then uptake of phosphorus have to completed. Therefor, mixture of anoxic and aerobic reactor was necessary for the high removal efficiency of nitrogen and phosphorus in INSUB.

• Journal of Wetlands Research
• /
• v.13 no.2
• /
• pp.363-375
• /
• 2011

Recently, Water quiality of urban river largely have gotten better by virtue of sewer pipe laying and sewage treatment plants construction. or the various contaminants which is flowed in into river have generated underwater ecosystem disturbance and red tide by lack of sewage and waste water disposal facilities. With tidal river, taehwa river of ulsan metropolitan city has large river width and gradual stream bed gradient at the dry and storage period. Moreover, the flow is paralyzed due to the bridge pier protection work, consist of the mat foundation which is about 1.2km from two bridge and the contaminant is accumulated. it is caused by of the red tide generated from the several years or it activates. In this study, When flow area is largest by changing independent footing of bridge pier of two bridges and using RMA2 model, we hydraulically analyzed a variable breadth of velocity and discharge. Consequently, flow rate increased the maximum 103%, discharge was exposed to increase the maximum 61%. Directly this cannot extinguish the red tide but suppresses the red tide occurrence or can reduce. And it is determined to prevent the depositioning of the contaminant and can control fundamentally the red tide occurrence cause.