• Environmental Engineering Research
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• 제24권2호
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• pp.202-210
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• 2019

In order to maximize the utilization of sewage sludge, a waste from wastewater treatment facility, the residual sewage sludge generated after lipid and carbohydrate extraction for biodiesel and bioethanol production was used to produce bio-oil by pyrolysis. Thermogravimetric analysis showed that sludge pyrolysis mainly occurred between 200 and $550^{\circ}C$ (with peaks formed around 337.0 and $379.3^{\circ}C$) with the decomposition of the main components (carbohydrate, lipid, and protein). Bio-oil was produced using a micro-tubing reactor, and its yield (wt%, g-bio-oil/g-residual sewage sludge) increased with an increase in the reaction temperature and time. The maximum bio-oil yield of 33.3% was obtained after pyrolysis at $390^{\circ}C$ for 5 min, where the largest amount of energy was introduced into the reactor to break the bonds of organic compounds in the sludge. The main components of bio-oil were found to be trans-2-pentenoic acid and 2-methyl-2-pentenoic acid with the highest selectivity of 28.4% and 12.3%, respectively. The kinetic rate constants indicated that the predominant reaction pathway was sewage sludge to bio-oil ($0.1054min^{-1}$), and subsequently to gas ($0.0541min^{-1}$), rather than the direct conversion of sewage sludge to gas ($0.0318min^{-1}$).

• 상하수도학회지
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• 제33권5호
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• pp.367-377
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• 2019

In this study, the fate and removal of 15 pharmaceuticals (including stimulants, non-steroidal anti-inflammatory drugs, antibiotics, etc.) in unit processes of a sewage treatment plant (STP) were investigated. Mass loads of pharmaceuticals were 2,598 g/d in the influent, 2,745 g/d in the primary effluent, 143 g/d in the secondary effluent, and 134 g/d in the effluent. The mass loads were reduced by 95% in the biological treatment process, but total phosphorous treatment did not show a significant effect on the removal of most pharmaceuticals. Also, mass balance analysis was performed to evaluate removal characteristics of pharmaceuticals in the biological treatment process. Acetaminophen, caffeine, acetylsalicylic acid, cefradine, and naproxen were efficiently removed in the biological treatment process mainly due to biodegradation. Removal efficiencies of gemfibrozil, ofloxacin, and ciprofloxacin were not high, but their removal was related to sorption onto sludge. This study provides useful information on understanding removal characteristics of pharmaceuticals in unit processes in the STP.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.195-195
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• 2003

Combustion generated fine particles, defined as those with aerodynamic diameters less than 2.5 m, have come under increased regulatory scrutiny because of suspected links to adverse human health effects. Transition metals are of particular interest due to the results of a number of studies that have shown cardiopulmonary damage associated with exposure to these elements and their presence in coal, residual fuel oils, sewage sludge, and other combusted fuels and wastes. This lecture will review results from multi-di sciplinary studies being conducted at EPA and elsewhere examining the physical, chemical, and toxicological characteristics of combustion generated particles. The research describes how collaborative work between combustion engineers and health scientists can provide insight on how combustion processes affect particle properties and subsequent health effects as measured by a combination of in-vitro and in-vivo studies using a variety of animal models. The focus of this lecture is on the interdisciplinary approach required to address the problem. Difficulties are discussed. Engineering aspects involved in this approach are described in detail. Physical and chemical characterizations are performed using a variety of analytical approaches including new techniques of x-ray absorption fine structure (XAFS) spectroscopy and x-ray absorption near-edge structure (XANES) deconvolution of these spectra to gather metal speciation information.

• 유기물자원화
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• 제28권1호
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• pp.65-72
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• 2020

본 연구는 초기 식종슬러지 종류별 CO₂의 생물학적 바이오메탄 생산 적용 가능성을 비교를 위해 국내 혐기성 소화조로부터 획득한 식종미생물을 종류에 따라 Specific methanogenic activity (SMA) test를 수행한 결과이다. 36일간의 실험 결과 CH₄ yield는 2,434-2,051mL CH₄/g COD의 범위를 얻었고 생산된 가스 내 CH₄ 분압은 맥주공장과 음식물류 폐기물 식종슬러지에서 가장 높은 89.3-91.9% CH₄ 분포를 보인 반면 하수슬러지 식종슬러지로부터 가장 낮은 효율을 나타냈다. 반응조의 CH₄ production rate/CO₂ consumption rate 비교를 통해 CH₄전환 속도 및 CO₂소비율의 간접적 물질 수지 비교가 가능했으며 SMA test 실험 기간 중 반응조 내 아세트산의 농도의 검출이 확인되었다. 이는 식종슬러지 내부의 잔류 유기물들의 분해, 식종미생물의 사멸 및 이들의 분해, Homoacetogenic bacteria의 활성에 의해 반응조 내 Metabolic pathway가 부분적으로 Hydrogenotrophic methanogenesis 단계에서 Acetoclasctic methanogenesis로의 변환됨에 따른 결과로 사료된다.

• 한국물환경학회지
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• 제32권3호
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• pp.297-302
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• 2016

Microbial electrochemical technology (MET) has recently been studied to improve the efficiency of a traditional anaerobic digestion (AD). The purpose of this study was to investigate the impact of MET in the system when MET was combined with traditional AD (i.e., AD-MET). Electrodes used in the MET were Cu coated graphite electrodes. They were supplied with a voltage of 0.3 V. AD started to generate methane in 80 days. But AD-MET started to generate methane from the initial operation after the system started. It was observed that AD-MET reached steady state faster and produced higher methane yield than AD. During the steady state, the average daily methane productions in AD and AD-MET were 2.3L/d and 4.9L/d, respectively. Methane yields were 0.07-CH₄/g‧CODre in AD and 0.25L-CH₄/g‧CODre in AD-MET. In AD-MET, the production rates of total volatile fatty acids (TVFAs) and soluble chemical oxygen demand (SCOD) were 0.12 mg TVFAs/mg VS‧d and 0.35 mg SCOD/mg VS‧d, respectively. They were significantly (p < 0.05) higher than those in AD. However, the concentrations of residual TVFAs in both systems were not significantly (p > 0.05) different from each other, confirming that methane conversion in AD-MET was greater than that in AD.

• 대한환경공학회지
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• 제28권1호
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• pp.42-47
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• 2006

생물학적 고도처리는 혐기, 무산소, 호기의 조건을 반복하거나 재배열함으로서 이루어지는데 이때 혐기조와 무산소조에서는 유기산이 발생한다. 여기서 발생한 유기산은 질소와 인의 제거와 슬러지침강성에 중요한 인자로 작용한다. 따라서 본 연구에서는 하 폐수 고도처리 시 F/M비 변화에 따른 유기산의 발생정도와 잔류농도 변화와 기에 따른 유기물과 질소의 제거 특성과 처리효율 및 슬러지 침강성과의 관계를 모색하기 위해 특성을 검토 하였다. 고도처리를 위해 $A^2/O$ 공정을 사용하였고 MLSS의 농도의 변화로 F/M비를 조절하였다. F/M비를 $0.16{\sim}0.08$ kg-BOD/kg-MLSS/day로 변화 시켰을 때 F/M비에 감소에 따라 회분식 반응기에 의한 유기산의 생성량의 증가하였고 잔류 유기산 농도는 감소하였다가 증가하였다. F/M비가 $0.16kg/kg{\cdot}d$ 실험 조건에서 SVI와 SS는 높게 나타났으며 F/M비가 $0.11{\sim}0.13kg/kg{\cdot}d$로 높아짐에 따라 감소하여 양호한 상태를 보이다 F/M비가 증가함에 SVI와 SS도 지속적으로 증가하여 $0.08kg/kg{\cdot}d$에서 높은 SVI와 SS 농도를 나타내었다. 무산소조의 유기산 잔류 농도 그리고 탈질률을 비교한 결과 무산소조의 유기산 잔류량이 적을수록 탈질률은 증가하였다. 슬러지 침강성과 질소 제거효율을 고려한 최적의 유기산 잔류 농도는 $1.4{\sim}2.2$ mg/L이며 이때의 F/M비는 $0.11{\sim}0.13$ kg-BOD/kg-MLSS/day범위로 나타났다.

• 대한환경공학회지
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• 제33권4호
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• pp.231-236
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• 2011

본 연구는 알루미늄 응집에 의한 인 제거 공정에 마그네슘 및 칼슘과 같은 2가의 금속이온을 첨가하였을 경우 인의 응집특성에 미치는 영향을 조사하였다. 인을 제거하기 위한 최적 알루미늄 응집 pH는 약 5~6 사이이며, 그 이상 pH에서는 TP 제거효율이 감소하였다. 마그네슘이나 칼슘과 같은 2가의 금속이온을 알루미늄 응집공정에 함께 사용할 경우 pH 6 이상 에서도 TP 및 $H_nPO_4^{n-3}$ 제거효율은 안정적으로 95% 이상을 유지하였다. 응집초기 $Al^{3+}/H_nPO_4^{n-3}$ (Al/P) 몰비가 3 이상에서 TP 제거효율이 80% 이상 높게 유지되었으며, 응집 후 잔류 TP 농도를 0.2 mg/L 이하로 제어하기 위해서는 Al/P 몰비는 약 6 이상 이었다. 마그네슘이나 칼슘 이온을 알루미늄 응집공정에 함께 사용할 경우 TP 제거를 위한 최적의 알루미늄 대비 마그네슘 및 칼슘 이온의 몰비($Al^{3+}/Mg^{2+}$ or $Ca^{2+}$)는 모두 2이었다. 알루미늄 응집공정에 마그네슘이나 칼슘 이온을 함께 사용하면, 동일한 양의 TP를 제거하기 위한 알루미늄 응집제 주입량이 감소하였고, 결과적으로 최종 슬러지 발생량도 감소하였다.