• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.32-40
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• 2001

It is desirable to reduce the amounts of fresh water and reuse the recycled water in papermaking process. In an attempt to improve the efficiency of recycling water refining treatment and to enhance the productivity of OCC recycling mill, up flow anaerobic sludge blanket(UASB) reactor was developed and introduced to Korea recently. In order to maximize the operating efficiency and minimize the adverse side effects it is imperative to estimate and evaluate the total effects of new system, UASB on the whole OCC recycling process. This study was carried out with a view to investigate the effects of the high temperature and alkalinity of process water on the quality ad productivity of testliner of OCC recycling mill which is equipped with UASB reactor and almost closed. Another object of this study was searching for the best available use of UASB treated process water. The results were as follows; Reuse of UASB treated water characterized with high temp and alkalinity was useful to improve the strength and drainage properties of recycled OCC owing to its good points of promoting OCC disintegration and reducing the calcium hardness of process water. However, it might not be avoidable to induce the increase of dissolved solids in process water in accordance with direct introducing of UASB treated water into the former stage of OCC stock preparation. So it would be advisable to adopt the UASB treated water in the stage of clean, screened OCC stock.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.2
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• pp.66-73
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• 2003

To investigate the availability of solidified wastes as resource, wastewater sludge, waste gypsum and fly ash were mixed and the results with various mixing ratios are as follows. Compressive strength turned out to be increasing as the amount of waste gypsum increases, keeps longer curing inhibition, and higher forming Pressure under the conditions of waste gypsum/sludge ratio 0.31-0.45, and 0.9kg cement as 15% and 1.2kg cement as 20% of total amount. Solidified agent under the fly ash/sludge ratio 0.45, 0.6, compressive strength seemed to be higher than standard one which means solidified wastes with these conditions could be applicable in real life. These results inform that concentrations of the leachate $Cr^{+6}$, Cu, Zn, Cd, Pb solidified matrix, containing low concentration of heavy metal, were cured with/without enough time it still will cause adverse effect on nature environment and application of heavy metal sequester must be needed to reuse industrial wastes from incineration plant solidified matrix. Total cost price, when considering manufacturing capability of the facilities for resourcerizing as 18,000ton was presented 678,664,000 won, as it were, manufacturing cost price was 37,704 won per ton. The results as above has shown that it's possible to use the mixture of waste gypsum/sludge, fly ash/sludge, cement, additions, and solidification matter as substitute of materials like brick, block, interlocking which has proper compressive strength of KS L 5201 and KS F 4004.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.4
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• pp.69-76
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• 2010

After feeding mixed samples, VS ranged from 60 to 80% of total costs in 15 days. EC ranged from1.21 to 2.45, 1.25 to 2.1 and 1.2 to 1.88mS/cm when worms were fed with a mixture of by-products of tidal current and sewage sludge, a mixture of by-products of algae producy, and food wastes and a mixture of by-products of algae producy, sewage sludge and food wastes. That means the kinds of mixture don't have any negative impacts on worms survival. With the feed with a mixture of by-products of algae producy and food wastes and a mixture of by-products of algae producy, sewage sludge and food wastes, pH shows stable 5.4 to 6.7, and 6.2 to 7.4 where is suitable for worms. But a mixture of by-products of algae producy and sewage sludge is out of proper scope for raising worms, in other words, extra care will be necessary. In case of Eh, a mixture of by-products of algae producy and sewage sludge make eh negative (-) in early stage so also when feeding worms, also extra care will be needed. NaCl ranged from 0.32 to 0.82% or form 0.23 to 0.61% when a mixture of by-products of algae producy and food wastes and a mixture of by-products of algae producy, sewage sludge and food wastes were fed. So taking care of salts will be essential whenever feeding.

• Journal of Environmental Science International
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• v.7 no.1
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• pp.81-88
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• 1998

This study was conducted to assess the characteristics of plgment wastewater and the removal rates of appropriate treatment by physical, chemical and biological Process, and the possibility of reuse for effluent. Based on the results, the wastewater qualities of pigment were pH 5.1$\pm$3.4, temperature 43.0$\pm$ 15.$0^{\circ}C$, BOD 1,431.4$\pm$589.6mg/l, COD 2,282.8$\pm$466.5mg/l, turbidity 1,340$\pm$820NTU, color 243.0$\pm$147.0unit, Pb 36.5$\pm$9.5mg/l and $Cr^+6$ 10.3$\pm$ 1.3mg/l, respectively. The removal rates of adsorption by activated carbon and filter process were BOD 40.6% , COD 57.0% , turbidity 89.6%, color 87.2%, Pb 86.0% and $Cr^+6$ 10.6%, respectively. And the removal rates of reduction, neutralization, coagulation and aP floatation process were BOD 18.2%, COD 24.3%, turbidity 74.3%, color 56.7%, Pb 68.6% and $Cr^+6$ 97.8%, respectively. The removal rates of activated sludge process were BOD 95.9%, COD 86.0%, turbidity 27.8%, color 25. 2%. Pb 26.9% and $Cr^+6$ 50.0% , respectively. The total removal rates of treatment by physical, chemical and biological process were BOD 98.0% , COD 95.4%, turbidity 98.1%, color 95.8%, Pb 97.0% and $Cr^+6$ 99.0%, respectively. According to the test results for possibility of reuse with coagulation-adsorption by activated carbon process of effluent, COD was higher than that of raw water and others were similar to that of raw water thus, it Is considered to be reused.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.47-60
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• 2007

The rapid development of economy in China at the expense of consuming huge amount of energy and resources, water resource in particular, which has resulted in the production and discharge of increasing amount of wastewater to the water environment. In order to effectively control the increasing water pollution trend, the State Council has stipulated that all the cities with population over 500,000 should reach wastewater treatment rate of 60% by 2005, and all the cities should reach the rate of 60% by 2010, of which Capital Beijing and all the province capital cities and important tourism cities should reach 70% then. By the end of 2005, of the 661 cities in China, 393 have built and operated municipal wastewater treatments with a total number of 790 sets, total treatment capacity of $80.91{\times}106m^3/d$ and total treatment rate of > 48%. Other 73 cities have started the construction of municipal wastewater treatment plants, and other 168 cities have started to prepare, planning and design of wastewater treatment plants. Most of municipal wastewater treatment plants in big cities in China operate normally and perform well with good quality of effluent in terms of wastewater treatment train, but the sewage sludge treatment is usually poor with big problems. It has been found that the small scale WWTPs using activated sludge process in the towns are usually operated and maintained abnormally because of lack of fund, skilled operators and energy. It is therefore suggested that the small scale MWWTPs in small cities and towns adopt appropriate technologies, of which the most available ones are multi-stage ponds, constructed wetlands and the combination of them for further purification and reuse of treated wastewater.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.1
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• pp.29-37
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• 2015

In this study, evaluating the system to reuse the sludge by improving such shortcomings as well as focusing on value using as fuel, instead of a simple process were assessed. Molding time required for 1ton of material is 31.8 ~ 115.0 minutes and power consumption per 1ton of material was estimated at 79.6kW and the shape of solid waste completed was in 22mm-long & wide square. It's 14mm, when converting solid waste in sectional area, which was acceptable to quality standard requiring 50mm or less. As a result of reviewing the quality of solid waste produced in this test, caloric value at sludge-waste mixing ration, 2 : 8 was 3,941kal/kg and, 8:2 was 4,924 kal/kg in maximum.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.271-282
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• 2020

Sewage treatment plants are social infrastructure of cities. The sewage distribution rate in Korea is reaching 94% based on the sewage statistics based in the year of 2017. In Korean sewage treatment plants, use of PAC (Poly Aluminum Chloride) accounts for 58%. It contains a large amount of impurities (heavy metal) according to the quality standards, however, there have been insufficient efforts to reinforce the standards or technically improve the quality, which resulted in secondary pollution problems from injecting excessive coagulant. Also, the increase in the use of chemicals is leading to the increases in the annual amount of sewage sludge generated in 2017 and the need to reuse sludge. As such, this study aims to verify the possibility of reusing sludge by evaluating the stability of heavy metals based on the injection of coagulant mixture during water treatment which uses the torrefield wood powder and natural materials, and evaluating the sedimentation and heating value of sewage sludge. As a result of analyzing heavy metals (Cr, Fe, Zn, Cu, Cd, As, Pb, and Ni) from the coagulant mixture and PAC (10%), Cr, Cd, Pb, Ni, and Hg were not detected. As for Zn, while its concentration notified in the quality standards for drinking water is 3 mg/L, only a small amount of 0.007 mg/L was detected in the coagulant mixture. Maximum amounts of over double amounts of Fe, Cu, and As were found with PAC (10%) compared to the coagulant mixture. Also, an analysis of sludge sedimentation found that the coagulant mixture showed a better performance of up to double the speed of the conventional coagulant, PAC (10%). The dry-basis lower heating value of sewage sludge produced by injecting the coagulant mixture was 3,378 kcal/kg, while that of sewage sludge generated due to PAC (10%) was 3,171 kcal/kg; although both coagulants met the requirements to be used as auxiliary fuel at thermal power plants, the coagulant mixture developed in this study could secure heating values 200 kal/kg higher than the counterpart. Therefore, utilization of the coagulant mixture for water treatment rather than PAC (10%) is expected to be more environmentally stable and effective, as it helps generating sludge with better stability against heavy metals, having a faster sludge sedimentation, and higher heating value.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.5
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• pp.583-590
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• 2015

Evaluation and comparison for the performance on the contracting-out became possible after the introduction of the performance indicators(PIs) in 2012 in Korea, And local governments and private companies are utilizing them as evaluation data to enhance the performance of the contracting-out. Several revisions on performance indicator were carried out by expert group on contents validity of PIs, But the review of the composition validity of PIs was not sufficient. In this study, the applicability, distinction ability and composition validity of PIs is evaluated by statistical method. From the results, Improvement of indicator is required in order to increase the interrelationship among indicators to enhance the compostion validity of indicators related with operation, sludge and water reuse.

• Journal of environmental and Sanitary engineering
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• v.21 no.3 s.61
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• pp.37-43
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• 2006

Recently, needs for reuse of sludge produced from WTP(water treatment plant) have been increased with shortage of landfill sites and difficulties of the treatment and disposal processes. Therefore, Reusing is becoming an Increasingly popular waste management alternative to divert waste from landfills. In order to research the characteristics of WTP sludges, we used the sludges of C WTP which intake the lake Dae-Cheong and the sludges of S WTP which intake Keum river, The specific surface area of C and S WTP sludges were $0.9986m^2/cc\;and\;1.874m^2/cc$, respectively. The gravity was about $2.0{\sim}2.4$ which are scope of peat or loamy clay. The major minerals of C WTP sludges were kaolinite(48.4%), muscovite(19.5%), and quartz(16.7%). Also, muscovite(31.6%), quartz(30.3%), and kaolinite(17.3%) in S WTP sludges were major minerals.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.715-718
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• 2001

This study uses traditional alum coagulation and sedimentation process to treat CMP wastewater from cleaning after polishing. The primary goal is to successfully recycle both solid fines and water for semiconductor manufacturing. Results indicated that CMP wastewater may be successfully treated to recover clean water and fine particles by alum coagulation. The optimum operating conditions for coagulation are as fellowing: alum dosage of 10 ppm, pH at 5, rapid mixing speed at 800 rpm, 5 min rapid mixing time, and long slow mixing time. The treated water with low turbidity and an average residual aluminum ion concentration of 0.23 ppm may be considered for reuse. The settled sludge after alum coagulation contains mainly SiO$_2$particle with a minor content of aluminum (1.7 wt%) may be considered as raw materials for glass and ceramic industry.