김윤주 Yun Ju Kim

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This study deals with the recycle of fine silyt soil wasted from aggregate washing plant for where concrete products are manufactured. This waste was substituted for feldsparthic mineral in preparation of clay body and glaze. A sintering behaviour and fusion characteristic of those clay products are described in this study. The results showed that particle size distribution of the fine silty soil was in the range of 1.82~2.60㎛ consisting mainly of feldspar. The cast body which contains 10~40% of this waste was appeared to be sintered at 1170~1200 ℃. The graze con be developed for glossing the clay body when 0~90% of this waste are used. It is concluded that this waste can be replaced for making a glossing glaze and finely sintered clay body.

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고영송 Young Song Ko , 박준석 Joon Seok Park , 이윤진 Yoon Jin Lee , 남궁완 Wan NamKoong , 나종철 Jong Chul Na , 서정호 Jung Ho Seo

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This study was performed to evaluate removal efficiencies of biofilters treating gasoline vapor with different gas injection modes. An up-flow, a step injection and a simultaneous up-flow and down-flow modes were chosen. A compost was used as biofilter media to treat gasoline vapor gas. Biofilters were operated for 85 days. Dehydrogenase activity was increased from approximately 3,000 to over 11,000㎍ TPF/g of dry compost on day 20 and remained at a relatively constant level. This phenomenon implies that 20 days was required to microbial acclimation. Maximum elimination capacities of the step injection and the simultaneous up-flow and down-flow mode biofilters were about 33g TPH/m3 of filling material/hr, whereas it was 22g TPH/m3 of filling material/hr for the up-flow mode biofilter. In case of the simultaneous up-flow and down-flow mode biofilters, removal efficiency at 25cm bed height (25cm from the bottom) was higher than that at 75cm bed height (25cm from the top). As a result of ANOVA(analysis of variation), the mean removal efficiency (56%) of the step injection mode was the highest among three modes (α = 0.05). Whereas it was the lowest as 43% in the up-flow mode biofilter. Overall carbon recovery was ranged from 47% to 89%.

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성낙창 Nak Chang Sung , 장성호 Seong Ho Jang , 정유진 Yoo Jin Jung

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Membrane technology for application in wastewater treatment has been developed recently. The membrane bioreactor is one important application. This is a system for solid-liquid separation of activated sludge using microfiltration or ultrafiltration. An important advantage of the membrane bioreactor is that it can attain complete solid-liquid separation independent of the quality of the mixed liquor. Running cost and energy consumption however, are still higher. Hence, it is important to replace membrane with non-woven filter which is lower price. After application of non-woven filtration, it can operate higher flux with lower pressure and complete solid-liquid separation. And removal efficiency of COD, BOD, T-N and T-P were achieved 93%, 98%, 65% and 60%, respectively. Nutrient removal efficiency in intermittently aerated process were considerably increased, comparing to conventional activated sludge.

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박동원 Dong Won Park , 성낙창 Nak Chang Sung , 전기일 Gee Ill Jun

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The objectives of this study were to remove organic matter, nitrogen and suspended solid in landfill leachate, we applied the intermittently aerated activated sludge process using submerged nonwoven filtration. The system was consisted of a bioreactor which had a working volume of 40L, and nonwoven modules submerged into bioreactor. The operating condition was aeration/nonaeration(120min/120min). The Air flow rate of diffusers was fixed at 12～15L/min. MLSS was roughly controlled between 5,000 and 12,000mg/L. Nonwoven module washing was conducted with chemical method(0.1NaOCl) after physical washing(Sponge ball). The results were as follows ; 1. Optimum CODCr volumetric loading rate was 1.1 kgCODCr/m3?day at MLSS 12,000mg/L. 2. CODCr removal efficiencies for PP-80 module and PP-100 module were 94.5% and 94.8%, respectively. 3. T-N removal efficiencies for PP-80 module and PP-100 module were more than 92% after increasing air flow as 15L/min.

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이의상 Eui Sang Lee , 황필기 Pil Ki Hwang , 최철호 Chul Ho Choi

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The main objectives of this study were to determine kinetic parameters from acid hydrolysis of starch and to maximize glucose conversion rate of low-grade starchy biomass using the optimum conditions determined from kinetic study. Kinetic study on dilute acid hydrolysis of commercial corn starch was performed on the basis of experimental results from a batch reactor. A simple pseudo first order series model was used for the reactions which considered to be a two-consecutive reaction mechanism, starch hydrolysis and glucose degradation. The experimental results were used to determine the kinetic parameters. Two different kinds of low-grade starchy biomass, bakery wastes(BW) and food wastes(FW), were hydrolyzed using the optimum conditions determined by kinetic study. Maximum glucose yields of 57-66g glucose/100g BW and 33-35g glucose/100g FW were achieved within 22.3min at 0.5% H2SO4 and 150℃. Food wastes and bakery wastes were turned out to be promising feedstocks for the production of valuable products through the fermentation of these hydrolysates.

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배재근 Chae Gun Phae , 황진우 Jin Woo Hwang , 고현백 Hyun Beak Ko , 고병산 Byung San Ko

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This study was executed for treatment of sewage and wastewater sludge by incineration system combined with dryer and it grasped the basic characteristics of sewage and wastewater sludge. Also, we carry out simulation regarding effective driving by verifying heat efficiency, using the characteristics of sludge. These sewage sludge has water content of 74.02%, average VS content of 10.70%, ash content of 15.27% and calorific value of 2,242kcal/kg which was measure by bomb calorific meter using dried solid(DS). And wastewater sludge has water content of 55.74%, VS content 21.84%, ash content 22.45% and calorific value 2087.81kcal/kg. As a result of simulation in incineration system combined dryer, which is on the basis of characteristics of sewage and waste water sludge, the total heat efficiency of dryer between inflowing hot air temperature of it and exhaust hot air temperature was around 80%. And we checked auxiliary fuel by the standard of average calorific value of sewage and wastewater sludge regarding the change of water cntents containing like 50, 55, 60, 65, 70, 75% and the standard sludge was 100kg/hour in incineration system. Following this, when sewage and waste water sludge has less than 60% of water content of raw sludge, calorie was not lack enough during burning and auxiliary fuel was also not needed.

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이동훈 Dong Hoon Lee , 권성환 Sung Hwan Kwon

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A feasibility study on the automatic composting process by monitoring of the condensate properties was conducted. The condensate properties had been suggested as substitutive operating indices in the aerobic composting process. It was considered that the variations of carbon chemical forms and NH4+ ion concentration of the condensate would represent the microbial gaseous metabolites of food waste. However, it was indicated a controversial point because these indices could not be measured or monitored at on-site. On the other hand, the advantage of pH of the condensate(pHcn) is that it is possible to monitor continuously at on-site. Monitoring of the pHcn showed same patterns with the variations of pH of the compost, which was one of the most popular indices in evaluating the composting process. Moreover, it would be possible to evaluate the extent of composting activity using the only monitoring of the pHcn.. Therefore, it could be considered as useful index to point out the abnormal conditions needed for operating conditioning, and the end time of each cycle during a fed-batch test in which food waste was input and treated periodically. That is, the monitoring data of the pHcn could offer enough information for the automatic operation in this kind of on-site composting process

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이용우 Yong Woo Lee , 고광범 Gwang Beom Ko , 배우근 Woo Keun Bae , 홍승희 Seung Hee Hong

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Abstract

A shortcut biological nitrogen removal (SBNR) process was tested to treat an ammonia rich (450~830 mgN/L) landfill leachate using a pilot-scale reactor. The SBNR process was intended to oxidize ammonia to nitrite and, then, to reduce it to nitrogen gas. The reactor consisted of an anoxic tanks (2 ㎡ in total), connected with liquid recycle at 2Q. The aerobic tanks contained suspended sponge media, making the reactors a suspended/attached-growth hybrid system. At HRT = 4~3 days, the aerobic tanks consistently accumulated nitrite, which was denitrified completely in the anoxic tank when recycled. The average ammonia oxidation efficiency was 90% and NO2--N/NOx-N ratio was 0.46. The average free ammonia concentration in the main ammonia oxidation tank was 3.7 mg/L. The CODCr removal efficiency was 88%, giving an quite consistent effluent concentration of 409 mg/L on average. the specific consumption of COD for denitrification, ?CODCr/?NOx-N, was 4.23. The value was higher than the theoretical value, but 33% lower than that observed during a complete nitrification (ammonia to nitrate) period in the same reactor. This implied that a SBNR process can save external carbon source when an internal supply in not sufficient of a post-denitrification is adopted.

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곽종명 Jong Myoung Gwak , 허탁 Tak Hur , 최우진 Woo Zin Choi , 이혜진 Hey Jin Lee

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The enormous amount of wastes which are generated along with the rapid growth of the economy have brought about various kinds of serious environmental problems. In particular, the effective management of plastics wastes are very important since they are not degradable by nature. In this study, a life cycle assessment study are conducted to identify the environmental aspects and to evaluate the potential environmental impacts associated with the material recycling of plastics wastes. The input/output categories considered in this study include electricity, fuel and water used in the process of material recycling and air emission, water emission and solid waste emitted from the recycling process. It is expected that the outcome of the study be used in order to derive an optimal waste management scheme, by comparing this LCA results with other recycling methods such as thermal recycling and chemical recycling in the near future.

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정병곤 Byung Gon Jeong , 이병헌 Byung Hun Lee , 박정웅 Jung Woong Park , 차수길 Soo Kil Cha , 정승현 Seung Hyun Jeong

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Laboratory investigation has been conducted to evaluate feasibility and characteristics of CTA gel as a microbial entrapping matrix for wastewater treatment. Compressive strength of pellet was examined at various mixing ratio of activated sludge and CTA gel. Compressive strength of pellet decreased as a content of sludge in the microbial entrapping matrix increased. The degree of decrease in compressive strength was negligible and maintained about 30kg/㎠ when the microbial content in gel matrix ranged from 10% to 30%, while the degree of decrease somewhat increased when the microbial content in gel matrix was 40%. Organic removal efficiency of pellet was examined depending on different mixing ratio of gel and sludge. It is thought that sludge content in gel matrix should be maintained above 20% in order to maintain stable reactor performance. Thus, it can be concluded that optimum mixing ration of sludge to gel matrix is 3 : 10 as a wet weight basis when considering reactor performance and mechanical strength of pellet simultaneously. Mechanical strength of pellet made of CTA gel exhibit excellent results and showed 5-10 times higher value comparing that of PEG pellet. Start-up period of this system was about 10 days. This means that start-up period of entrapping microbial cell process is considerably short comparing other biological process such as activated sludge process of biofilm process. Kinetic constants, Y, Ke, Ks, k were 0.133 mg VSS/mg COD, 0.0053/d, 0.108/d, 21.94 mg COD/l, respectively. Especially, Y value of this system was very low comparing that of conventional activated sludge process. This means that this system produce les excess sludge than other pervailing biological wastewater treatment system.

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이승희 Seung Whee Rhee , 정창환 Chang Hwan Jung , 최종욱 Jong Wook Choi

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The effect of barrier characteristics such as hydraulic conductivity and thickness on the movement of NAPL(Non-Aqueous Phase Liquid) leaking from UST(Underground Storage Tank) is examined to prevent the pollution of soil and ground water in unsaturated zone. Due to laboratory experiment for soil characteristics, hydraulic conductivity is decreased as particle size becomes small. And there is little to no effect of particle size on soil characteristics such as bulk density, porosity, and water content. Initially, movement of NAPL in vertical direction is more fast than that in horizontal direction because a gravity is the most important factor on movement of NAPL in unsaturated zone. As increasing a travel time, the effect of barrier is very important in contaminated volume of NAPL since the change of moving distance of NAPL is decreased. When the hydraulic conductivity of barrier is reduced to 1/3 time, the contaminated volume is deceased to about 50%. However, the contaminated volume is deceased only 23% although the thickness of barrier is increased to 3 times. Hence, the hydraulic conductivity of barrier is very important to control the movement of NAPL in unsaturated zone. The dimensionless group, Kt/T, represents the characteristics of barrier and the optimal dimensionless value is decided to about 50. When the dimensionless value is applied to the field example in which hydraulic conductivity is 1.0×10-6cm/sec, the moving distance of a front head of NAPL is estimated about 20 cm for 30 years.

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신대현 Dae Hyun Shin , 김상국 Sang Guk Kim , 이경환 Kyong Hwan Lee

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Characterization of the flow properties of plastics melts is one of the key factors for the successful operation of the plastics pyrolysis plant. Experiments for the viscosity measurement of plastics melt are carried out on the mixed plastics used for RDF, recycled HDPE, recycled LDPE, recycled PP, and mixed plastics being made according to the generation ratio of waste plastics. Experiments are performed to find out the following relationships : viscosity with the mixture ratio of plastics and waste oil, viscosity with temperature, and viscosity with the time elapsed at constant temperature. Experimental results show that viscosity is increased in log scale as the mixture ratio of plastics increase. When temperature is raised far enough above the melting point, viscosity dependence on temperature can be expressed as . Viscosity of the plastics melt decrease as time elapsed at constant temperature. Analytical result of the TGA and GPC confirms that decrease in viscosity is caused by the decrease of the molecular weight owing to the pyrolysis of the plastics melt in the viscinity of the melting vessel wall.

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김광렬 Kwang Yul Kim , 연익준 Ik Jun Yeon , 주소영 So Young Ju

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A study on applicable possibility on the open dumping landfill site of small scale which was situated in local small city was carried out to reuse the landfill site as the residental, commercial and other purposes through the analysis of the leachate of landfill, extracted solution from landfilled waste, and LFGs(landfill gases). The waste was landfilled at 5.5～8m depth and the covered layer so poor as 20～50cm thickness. The biodegradable organic matters were almost degraded and the result of the leachate of landfill showed that the BOD/CODMn ratio were measured as 0.079, pH 7.2～7.6, SS 47,727 mg/L, COD 6,194 mg/L, T-N 596 mg/L, and T-P 124 mg/L respectively. These results were higher than those of extracted solution of landfilled waste as the COD and BOD were measured as low values and T-N 7.77 mg/L and T-P as 0.20 mg/L lower concentrations the landfill appears the maturation phase. The concentrations of CO2 and methane were lower as 8.28 vol% and 1,247 mg/L but the concentrations of NH3 and H2S were 7 times and 12 times higher than TLV-TWA standard. The concentration of CH4 and other gases were lower than the ACGIH criterion. As the result of applicable possibility on the open dumping landfill, if appears that this landfill is maturation phase and the formation of LFGs and leachate is reduced. If the treatment facilities of NH3 and H2S gases and leachate from landfill and the layer which protects the inflow/infiltration is prepared, it can be safely used as this landfill site.

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이병헌 Byung Hun Lee , 이제근 Jea Keun Lee , 길대수 Dae Soo Gil

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Laboratory experiments were conducted to investigate on the effectivenss of electrolysis methods for the treatment of landfill leachate from municipal waste landfills. Electrolysis was investigated with various operating parameters, such as current density, retention time and electrode gap. In electrolysis, iridium coated with titanium(Ti/Ir) and stainless steel plate were used for anode and cathode respectively. The removal efficiency of organics and ammonia increased with current density and retention time, but decreased with increasing electrode gap. The removal of the pollutants in electrolysis is mainly attributed to the indirect oxidation effects of chlorine and hypochlorite. These results indicate that electrolysis process can be excellent method for the pretreatment of landfill leachate.

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김재영 Jae Young Kim , 이동훈 Dong Hoon Lee , 황선진 Sun Jin Hwang , 이정전 Jung Jun Lee , 이남훈 Nam Hoon Lee , 윤석표 Seok Pyo Yoon , 안영미 Young Mi Ahn , 남경필 Kyoung Phile Nam

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Abstract

The guideline to estimate economical damages caused by landfill leachate and gases are not well established, furthermore, the consensus on methodology has not been present in both scientific and public domains. The main reason can be attributed to the complicated natures of landfill leachate and gases so that the cause-and-effect can not be clearly verified. Therefore, the result is not decisive in most cases. The economical damages should be quantified in a scientific and reasonable manner, which is acceptable to both parties on disputes in order to compensate the damages, The present study has been conducted in an attempt to provide such guideline which can be used for settlement of disputes caused by the leachate and gases discharged from landfill. Once a dispute is filed, verification of the cause-and-effect should proceed followed by procedures to estimate damages on crop, livestock, and land(in case of this study). For this step, field investigation and collection of existing informations related to similar damages previously happened are essential. If necessary, available modeling tools can be adopted. Next step is to apply adequate procedures for the conversion of the damages to economical values. If the damage occurred is perennial such as in fruit-bearing trees, projected losses should be accounted for based on available informations and proven modeling tools. For complete and satisfactory settlement of disputes, however, a sufficient amount of data are needed to be accumulated.

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