• 상하수도학회지
• /
• 제34권6호
• /
• pp.425-435
• /
• 2020

Numerous chemical modifications on activated carbon such as acidic conditioning, thermal treatment and metal impregnation have been investigated to enhance adsorption capacities of micropollutants in water treatment plants. In this study, chemical modification including acidic, alkaline treatment, and iron-impregnation was evaluated for adsorption of 2,4-dichlorophenol (2,4-DCP). For Fe-impregnation, three concentrations of ferric chloride solutions, i.e., 0.2 M, 0.4 M, and 0.8 M, were used and ion-exchange (MIX) of iron and subsequent thermal treatment (MTH) were also applied. Surface properties of the modified carbons were analyzed by active surface area, pore volume, three-dimensional images, and chemical characteristics. The acidic and alkaline treatment changed the pore structures but yielded little improvement of adsorption capacities. As Fe concentrations were increased during impregnation, the active adsorption areas were decreased and the compositional ratios of Fe were increased. Adsorption capacities of modified ACs were evaluated using Langmuir isotherm. The MIX modification was not efficient to enhance 2,4-DCP adsorption and the MES treatment showed increases in adsorption capacities of 2,4-DCP, compared to the original activated carbon. These results implied a possibility of chemical impregnation modification for improvement of adsorption of 2,4-DCP, if a proper modification procedure is sought.

• 상하수도학회지
• /
• 제30권6호
• /
• pp.663-671
• /
• 2016

Coagulation/precipitation process has been widely used for the removal of phosphate within domestic wastewater. Although Fe and Al are typical coagulants used for phosphate removal, these have some shortages such as color problem and low sedimentation velocity. In this study, both Fe and Al were used to overcome the shortages caused by using single one, and anionic polymer coagulant was additionally used to enhance sedimentation velocity of the precipitate formed. Batch experiments using a jar test were conducted with real wastewater, which was an effluent of the second sedimentation tank in domestic wastewater treatment plant. Response Surface Methodology was used to examine the responsibility of each parameter on phosphate removal as well as to optimize the dosage of the three coagulants. Economic analysis was also done on the basis of selling prices of the coagulants in the field. Phosphate removal efficiency of Fe(III) was 30% higher than those of Fe(II). Considering chemical price, optimum dosage for achieving residual phosphate concentration below 0.2 mg/L were determined to be 18.14 mg/L of Fe(III), 2.60 mg/L of Al, and 1.64 mg/L of polymer coagulant.

• Membrane and Water Treatment
• /
• 제15권3호
• /
• pp.117-130
• /
• 2024

The possibility of using lime/mineral solvent solutions has been investigated to effectively remove T-P from wastewater. The lime solvent solution showed an initial T-P removal efficiency of about 90% compared to the less efficient mineral solvent solution removal. High pH and dissolved Ca2+ can form hydroxyapatite minerals (Ca5(PO4)3(OH) or Ca10(PO4)6(OH)2 and can also remove SS and COD from wastewater. Feldspar dissolution solution can be reused twice because the Ca limited sample content provided, but further research is needed to discover other influencing parameters that control the T-P removal efficiency in real wastewater. Because it plays an important role of alkalinity in T-P removal, the success rate is limited. In practical applications, it is obtained according to the pH value wastewater in the environment. The results obtained in this study can highlight new insights on the use of limestone/dissolved mineral solutions to control T-P in wastewater, instead of directly using commercial chemical agents that can produce large amounts of unreacted chemical sludge.

• 멤브레인
• /
• 제27권5호
• /
• pp.375-388
• /
• 2017

하 폐수 처리 기술은 종래 단순 오염물질 처리에서 에너지 및 자원 절약형의 고도처리 기술로 발전되고 있으며, 공공 수역으로의 오염 물질과 유독 물질 배출을 최소화하고 설치 운영의 효율성을 높이기 위해 IT 및 BT와 같은 다양한 기술을 접목한 융합형 기술로 진화하고 있다. 국내 하 폐수 처리기술의 발전 추이를 살펴보기 위해 등록된 특허기술을 수집 조사하여 연도별 부문별로 분류하여 분석하였다. 본고에서 2010년~2017년 5월 간의 관련된 특허 등록 내용을 생물학적 물리화학적 처리공정, 장치 및 기기, 소재 제재, 슬러지처리, 분리막, 공정제어기술 등 10개 분야의 42개 세부 영역으로 나누어 추세를 분석했다. 총 3,356건의 특허가 등록되었으며 2013년에 638건으로 최고치를 기록한 이후 다소 감소하여 연간 3~400여 건을 유지하고 있다. 등록된 특허 총 건수는 아직 다른 국가에 비해 적지는 않으나 공정 제어 및 기기 분야, 신개념 처리 기술과 같이 세계 시장을 선도할 수 있는 첨단 기술의 특허는 타 분야에 비해 미흡한 것으로 나타났다.

• 상하수도학회지
• /
• 제18권5호
• /
• pp.689-695
• /
• 2004

Electrocoagulation has been suggested as a promising alternative to conventional coagulation. The process is characterized by reduced sludge production, no requirement for chemical use, and ease of operation. However, this coagulation has scarcely been studied in water purifying process. This study was performed several batch experiments to compare turbidity removal between electrocoagulation and chemical coagulation. In addition, characteristics of floe were evaluated with zeta potential and particle size distributions. Electrocoagulation showed a relatively higher removal of turbidity (approximately 5%) with the same aluminum amount than conventional chemical coagulation. In addition, turbidity removal by electrocoagulation was less sensitive to pH and was greater for more extensive pH range than chemical coagulation. The results of zeta potential and floc size distributions illustrated that electrocoagulation provided the preferable conditions for coagulation such as zeta potential close to zero millivolt and increased portions of particles in the range of 40 and $100{\mu}m$.

• Ecology and Resilient Infrastructure
• /
• 제3권4호
• /
• pp.256-262
• /
• 2016

급격한 산업화와 인구증가로 인한 화학물질 사용량의 증가는 기존의 수 처리 방식의 대부분을 차지하는 생물학적 공정의 한계를 불러온다. 이와 같은 문제를 해결하기 위한 방법으로 고급산화공정의 하나인 오존 마이크로버블 기술이 최근 주목을 받고 있다. 본 논문에서는 마이크로버블의 물리학적 및 화학적 특성에 대해 논하고, 다양한 독성 오염물질의 제거를 중심으로 마이크로버블 오존산화공정을 분석하였다. 또한 다른 처리 기술과 결합한 오존 마이크로버블 기술의 용수 및 폐수처리 전망을 논하였다.

• 공업화학
• /
• 제24권1호
• /
• pp.38-43
• /
• 2013

ETA (ethanolamine)는 원자력 발전소 2차계통의 pH 조절제인 암모니아 대체 물질로 2001년부터 이용되고 있다. 환경적 측면에서 난분해성 유기물이며 현재 운영 중인 원자력 발전소 폐수처리설비로 처리가 불가능하다. 본 연구는 현장 시료를 사용하여 N와 COD 제거하기 위한 최적 공정과 사용 약품에 대하여 조사하였다. 폐수 중에 다량 함유되어 있는 ammonium ion은 diffused aeration system을 이용하여 95% 이상을 제거하고 혼합과산화물(sodium persulfate/sodium percarbonate)을 사용하여 산화시키고 응집제를 사용하여 물리 화학적으로 처리 후 90% 이상의 제거효과를 얻을 수 있었다.

• Environmental Engineering Research
• /
• 제17권2호
• /
• pp.59-63
• /
• 2012

This paper proposes a modified Ludzack-Ettinger (MLE) type membrane bioreactor (MBR) as a method of treatment for wastewater from food waste disposer. Micro-membrane filtration allows for an extremely low concentration of suspended solids in the effluent. The effluent of the reactor in question is characterized by a relatively high level of non-biodegradable organics, containing a substantial amount of soluble microbial products and biomass. Results obtained in this paper by measurement of membrane fouling are consistent with biomass concentration in the reactor, as opposed to chemical oxygen demand (COD). The MLE process is shown to be effective for the treatment of wastewater with a high COD/N ratio of 20, resulting in are markedly high total nitrogen removal efficiency. Denitrification could be improved at a higher internal recycle ratio. Despite the low concentration of influent phosphorus, the phosphorus concentration of the outflow is seen to be relatively high. This is because outflow phosphorous concentration is related to COD consumption, and the process operates at along solids retention time.

• Journal of Electrochemical Science and Technology
• /
• 제13권2호
• /
• pp.261-268
• /
• 2022

In this study, electrochemical treatment of urban wastewater with electrical conductivity of 1000 μS cm^-1 and chemical oxygen demand of 250 mg L^-1 was investigated using the variables of initial pH value, current density and flow rate. Electrocoagulation was used, in which aluminum and stainless steel were selected, as the electrochemical treatment process. The electrocoagulation process was operated in continuous mode. The data obtained in experimental studies show that the best COD removal efficiency occurred in experiments where the initial pH value was 6. The increase in current density from 5 A to 15 A decreased the removal efficiency from 79 to 67%. The increase in flow rate under constant current density also reduced the efficiency of removal as expected. In experiments in which current density and flow rate were examined together, the increase in flow rate allowed the application of higher current densities. This situation led to considerable reductions in energy consumption values, even if the COD removal efficiency did not significantly increase. The high COD removal obtained with the use of high flow rate and high current density indicates that the electrocoagulation process can be used for high flow rate municipal wastewater treatment.

• Environmental Analysis Health and Toxicology
• /
• 제29권
• /
• pp.15.1-15.7
• /
• 2014

Objectives This paper tried to review a recent research trend for the environmental exposure of engineered nanomaterials (ENMs) and its removal efficiency in the nanowaste treatment plants. Methods The studies on the predicted environmental concentrations (PEC) of ENMs obtained by exposure modeling and treatment (or removal) efficiency in nanowaste treatment facilities, such as wastewater treatment plant (WTP) and waste incineration plant (WIP) were investigated. The studies on the landfill of nanowastes also were investigated. Results The Swiss Federal Laboratories for Materials Science and Technology group has led the way in developing methods for estimating ENM production and emissions. The PEC values are available for surface water, wastewater treatment plant effluents, biosolids, sediments, soils, and air. Based on the PEC modeling, the major routes for the environmental exposure of the ENMs were found as WTP effluents/sludge. The ENMs entered in the WTP were 90-99% removed and accumulated in the activated sludge and sludge cake. Additionally, the waste ash released from the WIP contain ENMs. Ultimately, landfills are the likely final destination of the disposed sludge or discarded ENMs products. Conclusions Although the removal efficiency of the ENMs using nanowaste treatment facilities is acceptable, the ENMs were accumulated on the sludge and then finally moved to the landfill. Therefore, the monitoring for the ENMs in the environment where the WTP effluent is discharged or biomass disposed is required to increase our knowledge on the fate and transport of the ENMs and to prevent the unintentional exposure (release) in the environment.