• KSBB Journal
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• v.16 no.4
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• pp.389-397
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• 2001

The effect of sludge digestion on the leaching efficiency of heavy metals from sludge by bioleaching with Thiobacillus thiooxidans MET was investigated. The used sludges were a non- and anaerobically digested. The leaching efficiency of heavy metals was strongly dependent on the pH of the sludge solution rather than the sludge condition and stolid concentration. The lower the pH the more heavy metal was leached from 3.0 of pH. The sequent orders of leaching heavy metals were Zn, Cu, and Cr. Although the buffering capacity of non-digested sludge was similar to anaerobically digested sludge, the pH decrease rate of the anaerobically digested sludge solution was faster than that of the non-digested sludge solution due to the higher sulfur oxidation rate of T. thiooxidans MET in the anaerobically digested sludge. The amount of leached heavy metals from the anaerobically digested sludge showed higher than that of non-digested sludge at the same pH value. This result might be caused by the difference of the insoluble metal types, which were contained in the sludge. An increase in sludge solids concentration decreased the leaching efficiency of heavy metals in the range of solids concentration 10 g/L to 70 g/L. The optimum ratio of S° to sludge stolid was 0.1 in both the sludge. The bioleaching process of heavy metals with T. thiooxidans MET showed the disinfecting effect over 90% as well as the reduction effect in sludge weight of 20%.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.98-105
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• 2007

The objectives of this study were to demonstrate that enhanced anaerobic digestion could be achieved by adopting ultrasonic cavitation pretreatment on the basis of the biogas production and to compare the simulation results of ADM1 (Anaerobic Digestion Model No. 1) with results of the experimentally operated digester the ultrasonic pretreatment of sewage sludge showed the hindered effect on the dewaterbility and the increase of SCOD production. In this study, four sets of lab-scale anaerobic digester were operated with untreated(control), 30 min, 60 min and 90 min ultrasonic pretreated sludge. TCOD removal efficiencies in digesters of control, 30, 60, 90 min sonicated sludge were 31.9%, 37.9, 38.5% and42.2%, and 75 removal were 15.9%, 20.8%, 21.5%, 24.1% respectively. Also more biogas was produced gradually with the increased sludge loading and the pretreatment time. Overall the simulation results had a correspondence tendency with the experimental efficiencies.

• Journal of the Korean GEO-environmental Society
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• v.23 no.7
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• pp.5-10
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• 2022

The industrial waste is becoming a big problem in the aspect of spatial and environmental in domestic and international. Therefore, the waste reduction and recycling policy has been being implemented as a way to solve this problem. The engineered stone sludge, which is waste, is generated duing the engineered stone production process. since engineered stone sludge is mostly treated by landfill, an increase in the amount of the sludge leads to an increase in landfill sites and treatment costs. therefore, there is a need for a method of resourcization with engineered stone sludge. So, laboratory tests (Plastic and liquid limits, compaction, unconfined compression and permeability test) were conducted to confirm the possibility of using engineered stone sludge mixed with weathered granite soil as a cover material for landfill in this study. The result shows that the mixed soil material with less that 62.5% of engineered stone sludge can be used as a cover material for landfill.

• Resources Recycling
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• v.18 no.3
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• pp.55-61
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• 2009

Dewatering process to remove water from pigment sludge was important in the diverse aspects of the improvement of product quality, curtailment of the drying cost and the transportation. It was difficult to dewater pigment particles with the mechanical forces because the size was fine under $5{\mu}m$. Thermal filter press dewatering equipment composed of squeezing plate and a fixed heating plate was developed to improve the dewaterability of pigment the sludge as supplying the heat from the fixed heating plate to the cake. Several tests that estimate the dewaterability for pigment sludge as with or without squeezing process and the difference of dewatering time was conducted with this equipment. Dewaterability of thermal dewatering under squeezing process was increased about 20% compared with non squeezing process. Under squeezing process, thermal dewatering tests changing dewatering time with 70 and 80 minute were conducted respectively. The water content of cake was more reduced at dewatering time of 80 minute compared with 70 minute, and dewatering velocity was also decreased, which caused the productivity of thermal filter press to drop. It was observed that clogging of filter cloth didn't almost occur because the liquid was discharged from cake layer easily. In this research, it was resulted that the squeezing process and long dewatering time were effective to improve the dewaterability of pigment sludge. So, this thermal filter press equipment was useful for dewatering the fine particle sludge like pigment.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.832-835
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• 2009

폐기물의 감량화 및 자원화 기술 중 가장 대표적인 기술로 폐기물의 가스화 용융 기술을 들 수 있다. 폐기물 가스화 용융 기술은 폐기물 내의 탄소 및 수소 성분은 가스화 하여 CO, $H_2$가 주성분인 합성가스(synthesis gas, syngas)로 전환하고, 불연물은 용융하여 환경적으로 무해한 슬래그 또는 금속으로 회수하는 기술이다. 본 연구에서는 고발열량폐기물과 탈수슬러지 혼합가스화를 통하여 생산된 합성가스를 합성가스 압축기를 통하여 유용한 원료물질을 제조하는 공정인 수성가스 전환 반응(water gas shift reaction)과 가스화 반응기의 보조연료로 투입하기 위한 합성가스 압축, 이송 시스템의 운전 특성을 고찰하였다. 그 결과 고발열량폐기물과 탈수슬러지 혼합가스화에서 합성가스는 안정적으로 발생하였으며, 합성가스 압축, 이송시스템을 위한 정제설비에서의 분진제거는 99.07 %의 효율을 얻었고, 또한 합성가스 재순환 장치의 성능시험을 통하여 대기 중의 산소가 유입이 안 되는 기밀성을 확인하였다. 합성가스 압축, 이송 공급 유량 제어 실험 결과로는 합성가스 압축기 기동 시 합성가스 압축압력과 공급유량은 비례적으로 증감하는 것을 알 수 있었다.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.599-609
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• 2015

In order to investigate why OSA (oxic-settling-anaerobic) process produces less sludge than CAS (conventional activated sludge) process, sequential cultivation through 1^st aerobic-anaerobic-2^nd aerobic conditions, were carried out. Then, the intracellular concentrations of adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD and NADH), and nicotinamide adenine dinucleotide phosphate (NADP and NADPH) were monitored for these three stages. Results showed that the concentrations of these energy substances rapidly decreased through time in both aerobic and anaerobic conditions but the anaerobic culture contained the lower energy level than aerobic culture. The 2^nd aerobic culture that experienced anaerobic condition showed lower concentration of these energy substances than those of the 1^st aerobic culture. Meanwhile, the anaerobic culture corresponding to the sludge holding stage of OSA was subjected to different soluble chemical oxygen demand (SCOD) levels, detention time, and temperature to evaluate the effects of these variations on the energy level difference between the 1^st and 2^nd aerobic stages. The lower the SCOD concentration, the longer detention time; and the higher temperature in the anaerobic stage tended to further reduce the intracellular level of the 2^nd aerobic culture. On the average, the intracellular energy level of the anaerobic and 2^nd aerobic stage were 57.73% and 39.12% of the 1st aerobic culture, respectively. These indicated that the insertion of an anaerobic stage between two aerobic stages could lower the intracellular energy levels, hence the lower the sludge in OSA than CAS process. Moreover, manipulation of the operating conditions of the intervening anaerobic stage can change intracellular energy levels thereby controlling sludge production.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.304-310
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• 2007

The purpose of this research was to investigate the effects of the co-treatment of municipal wastewater with microwave-irradiated excess sludge on the treatment efficiency and excess sludge production of the activated sludge process. When 250 mL of excess sludge with a MLSS concentration of approximately 2,000 mg/L was microwave-irradiated at $20^{\circ}C$ for $40\sim300$ sec by a microwave oven (2,450 MHz, 700 W), the temperature of the sludge increased at a rate of approximately $20^{\circ}C/min$ and the SCOD, TKN and T-P concentrations of the sludge showed the highest increase in the irradiation time of $40\sim130$ sec. And, the oxygen uptake rate measurement of the sludge microorganism suggested most of the microorganisms in the sludge were destroyed at an irradiation time above 130 sec(above $65^{\circ}C$). When the municipal wastewater and microwave-irradiated excess sludge was co-treated by the activated sludge process, almost no effect was observed in the pH and alkalinity of both the influent and effluent, but the influent concentrations of SS, COD, T-N and T-P increased. Even though the effluent SS, BOD and T-P concentrations showed almost no effect, the COD and TKN concentrations increased. The microbial yield coefficient decreased at a rate of 0.91 g SS/g COD removed as the irradiation ratio increased at a rate of 1 g SS/g SS-day.

• 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.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.476-481
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• 2005

2004년말 현재 국내에서 발생되는 음식물쓰레기의 재활용량은 전체 발생량의 $87.7\%$인 10,015톤/일이며, 전체 재활용량의 $6.47\%$인 640톤/일 정도가 혐기성소화 방법에 의해 처리 및 자원화 되고 있다. 국내에서 적용되고 있는 음식물쓰레기 혐기성소화 기술의 대부분은 습식소화(Wet digestion) 공법이며, 처리 방법별로 2상 혐기성소화(Two-phase anaerobic digestion)와 하수슬러지 흑은 축산분뇨와 함께 혼합처리 하는 통합소화(Co-digestion) 공정으로 구분되고 있다. 음식물쓰레기의 자원화 방법에 있어 혐기성소화는 사료화, 퇴비화에 비하여 폐기물의 효과적인 감량화와 자원화 효과뿐만 아니라 유용 에너지원인 메탄가스의 회수가 가능하기에 최근에 주목을 받는 biotechnology중의 하나로 자리매김 하고 있으며, 또한 유기성폐기물의 자원순환형 관리 시스템 구현에 있어 적절한 대안으로 고려되고 있다.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.395-406
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• 2010

In this study, anaerobic digestion, electro-oxidation and electro-fenton oxidation processes were investigated to reduce oily refinery sludge. Anaerobic digestion process was not suitable for oily activated sludge reduction because of characteristics itself and, as experimental results revealed, reduction efficiency was low for electro-oxidation process. However, 40% total suspended solid reduction of oily activated sludge was obtained by electro-fenton oxidation process, operating at pH=1, 0.5 A and $Fe^{2+}$:$H_2O_2$ ratio = 1:30. In addition, higher reduction efficiency was obtained as reaction time was increased (30, 60, 90, 120 min) despite of low $H_2O_2$ concentration. From the results, it has been investigated that electro-fenton oxidation is efficient process for oily activated sludge reduction.