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

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.106-114
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• 1998

This study was carried out for the purpose of industrial reuse of effluent released from activated sludge unit by $\gamma $-ray irradiation technique. The dissolved organic carbon in the effluent of an activated sludge unit is mostly refractory or inert material which are difficult to be degraded by micro organism. The effluent generated from activated sludge unit was irradiated with Co$^{60}$ $\gamma $-ray under condition of air bubbling. The effects of irradiation on the pH, COD, TOC, color, molecular weight distribution were investigated by membrane filtration and u.v.-spectrum analysis. With increasing dose, the TOC was decreased smoothly. The COD was increased at lower dose, while the COD was decreased at higher dose. The TOC and COD, however, were decreased smoothly when TiO$_{2}$ was added to the solution. It was thought that the differential decreasing trend of COD and TOC in according to the absence or presence of TiO$_{2}$ was due to the molecular weight distribution shifted from group of higher molecular weight to group of lower one which are more easy to be decomposed. The removal efficiency of color was 71.5% and it was increased to 85.7% when TiO$_{2}$ was added to the solution. The $\gamma $-ray irradiation was effective on the production of chlorine.

• Advances in environmental research
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• v.5 no.2
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• pp.141-151
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• 2016

Large amounts of aluminum hydroxide ($Al(OH)_3$) exist in water purification sludge (WPS) because of the added aluminum coagulant in water treatment process. Notably, $Al(OH)_3$ is an amphoteric compound, can be dissolved in its basic condition using sodium hydroxide to form aluminate ions ($Al(OH)_4{^-}$). However, in a process in which pH is increasing, the humid acid can be dissolved easily from WPS and will inhibit the recovery and reuse of the dissolved aluminate ions. This study attempts to fix this problem by a novel approach to separate $Al(OH)_4{^-}$ ions using nanofiltration (NF) technology. Sludge impurity in a alkaline solution is retained by the NF membrane, such that the process recovers $Al(OH)_4{^-}$ ions, and significantly decreases the organic matter or heavy metal impurities in the permeate solution. The $Al(OH)_4{^-}$ ion is an alkaline substance. Experimental results confirm that a recovered coagulant of $Al(OH)_4{^-}$ ion can effectively remove kaolin particles from slightly acidic synthetic raw water.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.895-904
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• 2006

The improved MLE (modified Ludzack-Ettinger) process was operated for piggery waste treatment in full-scale public livestock waste treatment plant. The treated waste from bioreactor was suitable for the strict effluent standard of 200 mgCOD/L and 60 mgTN/L as it was dewatered chemically without settling tank and passed through filtration process. Though this treatment method produced a great deal of sludge ($6.4m^3\;per\;m^3$ dewatered piggery waste) it was able to accomplish predominant effluent quality by removing non-biodegradable COD and color without advanced oxidation process as ozone, fenton and etc.. The nitrogen removal efficiency of bioreactor was rapidly declined from March to May (from 0.016 to 0.005 kgN/kgVSS-day) when disinfection is in earnest as well as from warm season when reactor temperature rises higher than $35^{\circ}C$(from 0.016 to 0.008 kgN/kgVSS-day). This study proves that counterplanes for infection residuals, bioreactor temperature and dewatering sludge reduction are necessary for piggery waste treatment.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.43-50
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• 2011

As a result of population growth and economic growth, household and industrial wastes continue to rapidly increase every year. Especially, sewage sludge produced at final stage is increasing with the constant construction and putting in good order of the sewage plant. In addition to the government's prohibition for filling up the sludge, it became more and more difficult to discharge wastes to the sea as London Dumping Convention '96 came into effect. And sewage sludge and the livestock wastes are expected to be thoroughly prohibited from discharging to the sea from 2012. So we need desperately economical and useful alternatives to compact and reuse these wastes. The purpose of this study is to evaluate the utilization of solidified sludge-soil mixture as an enhancement and covering material. To determine the proper mixed ratio of solidified sludge, this study conducted basic physical properties tests, compaction tests, uniaxial compression tests, and permeability test. It was found that the higher the ratio of solidified sludge, the lower the coefficient of permeability. Upon the results of particle size distribution, the mixed ratio of solidified sludge that meet the enhancement material condition was 59% or lower for SP granite soil and 48% or lower for SM granite soil respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.111-116
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• 1998

This studies regarding development of product system on artificial aggregate using of Paper Sludge Ah that waste production at paper-making mill, expecially this paper describes development of product system using centrifugal mixer plant. The skills of this product system on artificial aggregate using of Ash can be spread Fly-Ash, powder and fine aggregate(under 5mm) of waste concrete reuse.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.495-502
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• 2020

The 37 indicators for performance evaluation of public sewage management agencies are divided into four major categories (agency manpower management ability, wastewater treatment plant operation and management, sludge and water reuse, service quality) in the first stage, and the necessity and score acquisition for the detailed indicators by each major category in the second stages. Priority was investigated through the Analytic Hierarchy Process (AHP) analysis technique for ease and relevance of company efforts. Also, based on the results of this analysis, integrated type weighting and relative importance were analyzed. As a result of the analysis, the weight and relative importance of the first stage classification were in the order of wastewater treatment plant operation and maintenance, operation agency manpower management ability, sludge and water reuse, and service quality. As a result of analyzing the weights and priorities of the detailed performance indicators in the second stage, it was found that operator's career years, the percentage of certification holding rate in operators, compliance with the effluent water quality standards, training times for operators, and efforts to manage hazardous chemicals were important. Some of the indicators of operation agency performance evaluation may include indicators in which the performance of the company's efforts is underestimated or overestimated. In order to improve this, it is necessary to give weights in consideration of the necessity of the indicator, the relevance of the company's efforts, and the ease of obtaining scores.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.105-112
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• 2005

Stabilizing and rousing sludge water generated from washing truck mixer and batcher plant can resolve inconsistency in quality and improve strength, therefore it is essential to review how to utilize it. This research conducted experiments and studied on solids of sludge water to find out the types of stabilizing agents available in conditions of producing ready mixed concretes in Korea. The result showed that oxy carboxylic acid retarder dedicated for stabilizing sludge water was most effective in decreasing solid. However, the setting time of cement paste was retarded due to surplus reactants, but it did not impede application of ready mixed concretes. When we left the sludge water mixed with stabilizing agent, it has been noted that initial retard effect recovered to the level using just service water in 7${\~}$8 days and that it is effective to use stabilized sludge water in 2${\~}$3 days. On the other hand, saccharic type super retarding agent was also outstanding in applicability by showing similar effect. The sludge water stabilizing agents currently marketed depend on imports, therefore it is necessary to locally manufacture usable stabilizing agents and to review its usability with multi-dimensional view.

• 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 Geosynthetics Society
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• v.14 no.4
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• pp.159-165
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• 2015

In this study, the coefficient of permeability for cement mixtures including the powdered sludge of basalt, sand or fly ash with different mixed ratios was measured in order to reuse the powdered sludge of basalt in Jeju Island as the cut off materials. As the permeability test results, the coefficient of permeability for the cement mixtures with fly ash was increased with increasing the fly ash contents. The amount of fly ash in the cement mixtures should be mixed with less than 8 %. Meanwhile, the coefficient of permeability for the cement mixtures with sand was increased with increasing the sand contents. The amount of sand in the cement mixtures should be mixed with less than 40 %. According to the comparison result of cement mixtures including fly ash or sand, it is more advantageous to put the sand into the cement mixtures, rather than mixing the fly ash.