• 상하수도학회지
• /
• 제30권3호
• /
• pp.285-291
• /
• 2016

There has been an accelerating increase in water reuse due to growing world population, rapid urbanization, and increasing scarcity of water resources. However, it is well recognized that water reuse practice is associated with many human health and ecological risks due to numerous chemicals and pathogenic microorganisms. Especially, the potential transmission of infectious disease by hundreds of pathogenic viruses in wastewater is one of the most serious human health risks associated with water reuse. In this study, we determined the response of different bacteriophages representing various bacteriophage groups to chlorination in real wastewater in order to identify a more reliable bacteriophage indicator system for chlorination in wastewater. Different bacteriophages were spiked into secondary effluents from wastewater plants from three different geographic areas, and then subjected to various doses of free chlorine and contact time at $5^{\circ}C$ in a bench-scale batch disinfection system. The inactivation of ${\phi}X174$ was relatively rapid and reached ~4 log10 with a CT value of 5 mg/L*min. On the other hand, the inactivation of bacteriophage PRD1 and MS2 were much slower than the one for ${\phi}X174$ and only ~1 log10 inactivation was achieved by a CT value of 10 mg/L*min. Overall, the results of this study suggest that bacteriophage both MS2 and PRD1 could be a reliable indicator for human pathogenic viruses for chlorination in wastewater treatment processes and water reuse practice.

• Environmental Engineering Research
• /
• 제25권3호
• /
• pp.384-392
• /
• 2020

The presence of high fluoride concentration (> 1.5 mg/L) in water causes serious health problems such as fluorosis, infertility, brain damage, etc., which are endemic to many places in the world. This study has investigated the fluoride removal capacity of the novel activated biochar (BTS) and hydrochar (HTS) using Teff (Eragrostis tef) straw as a precursor. Activated biochar with mesoporous structures and large specific surface area of 627.7 ㎡/g were prepared via pyrolysis process. Low-cost carbonaceous hydrochar were also synthesized by an acid assisted hydrothermal carbonization process. Results obtained from both adsorbents show that the best local maximum fluoride removal was achieved at pH 2, contact time 120 min and agitation speed 200 rpm. The thermodynamic studies proved that the adsorption process was spontaneous and exothermic in nature. Both adsorbents equilibrium data fitted to Langmuir isotherm. However, Freundlich isotherm fitted best for BTS. The maximum fluoride loading capacity of BTS and HTS was found to be 212 and 88.7 mg/g, respectively. The variation could primarily be attributed to a relatively larger Surface area for BTS. Hence, to treat fluoride contaminated water, BTS can be promising as an effective adsorbent.

• 대한환경공학회지
• /
• 제39권7호
• /
• pp.377-384
• /
• 2017

본 연구는 환경부 시범사업으로 진행된 수원시 물 재이용(중수도)시설물 설치사업으로 설치된 물재이용시설을 통하여 건축물 단위의 물재이용을 통한 물 부족 문제 해결 가능성을 살펴보았다. 개별 건축물 단위의 물재이용이 이루어지며 도시의 물 수요를 최대 25%까지 줄일 수 있다. 이는 우리나라의 수자원 부족 문제를 해결할 수 있는 수준이다. 하지만 개별 건축물 단위의 물 재이용 시설을 활성화하려면 사용자의 중수도 거부감 해소와 경제성 문제를 해결하여야 한다. 중수도 거부감 해소는 MBR 공정과 AOP 공정을 연계 하였을 경우 해결 가능하다. MBR 공정과 AOP 공정을 연계하여 운영할 시 사용자들은 상수도와 중수도의 수질 차이를 느끼지 못하는 것으로 나타났다. 경제성 문제는 건설비와 운영비를 고려할 경우 시설용량 100톤/일 이상, 운영비만 고려할 경우 15톤/일 이상일 경우 상 하수도요금 수준에서 해결이 가능하다. 더 나아가 사회적 편익비용까지 고려할 시 150톤/일 이상부터는 수익이 창출되는 것으로 나타났다.

• Structural Engineering and Mechanics
• /
• 제47권4호
• /
• pp.545-557
• /
• 2013

Disposal of construction wastes poses major challenge to the municipal administration in the developing countries. At the same time new developments in these countries are unscrupulously exploiting the natural resources. The sustainable development requires judicious and careful utilization of natural resources. In this context, reuse of construction and demolition waste can save the global natural resources to greater extent. In this work the bricks and concrete waste from construction sites were crushed to the desired sizes and mixed in various proportions to study its properties in the concrete both in fresh and hardened states. Six mixes of natural and recycled aggregates were used to make the coarse aggregates for the concrete. From each mix nine cylinders were cast, which were tested at 7,14 and 28 days. The properties of concrete with recycled aggregates were compared with the control mix having natural aggregates. The nominal ratio of cement sand and coarse aggregates were kept at 1:2:4 by weight for all mixes. The tests have shown that concrete with recycled aggregates made from old concrete and brick bats provide greater opportunities for reuse of construction wastes in concrete.

• Membrane and Water Treatment
• /
• 제11권5호
• /
• pp.323-331
• /
• 2020

With the increasing demand on reverse osmosis (RO) membranes for water purification worldwide, the number of disposed membrane elements is expected to increase accordingly. Thus, recycling and reuse of end-of-life RO membranes should be a global environmental action. In this work, we aim to reuse the spent RO membrane for nanofiltration (NF) and ultrafiltration (UF) process by subjecting the spent membrane to solvent and oxidizing solution treatment, respectively. Our results showed that solvent-treated RO membrane could perform as good as commercial NF membrane by achieving similar separation efficiencies, but with reduced water permeability due to membrane surface fouling. By degrading the polyamide layer of RO membrane, the transformed membrane could achieve high water permeability (85.6 L/㎡.h.bar) and excellent rejection against macromolecules (at least 87.4%), suggesting its reuse potential as UF membrane. More importantly, our findings showed that in-situ transformation on the spent RO membrane using solvent and oxidizing solution could be safely conducted as the properties of the entire spiral wound element did not show significant changes upon prolonged exposure of these two solutions. Our findings are important to open up new possibilities for the discarded RO membranes for reuse in NF and UF process, prolonging the lifespan of spent membranes and promoting the sustainability of the membrane process.

• 멤브레인
• /
• 제26권1호
• /
• pp.70-75
• /
• 2016

본 연구에서는 하수처리수를 원수로 사용하여 직접 접촉식 막증발법을 적용하여 원수 온도와 원수 유량 변화에 따른 하수처리수의 COD, TN, TP, TOC의 제거율 변화와 여과플럭스의 변화를 측정하였다. 또한 하수처리수에 의한 분리막의 오염 가역성을 평가하기 위해 1차 증류수만을 사용하여 물리세정을 수행한 후 플럭스의 회복률을 측정하였다. 실험결과 원수의 온도 및 유량에 관계없이 원수가 3배 농축될 때까지 여과를 진행하였음에도 불구하고 하수처리수의 주요 오염물질인 COD, TN, TP, TOC에 대한 제거율이 92% 이상으로 높게 나타났다. 또한 비교적 낮은 온도인 $50^{\circ}C$와 $60^{\circ}C$에서 원수의 유량에 따라 최소 13.8 LMH에서 20.3 LMH로 높은 여과플럭스를 나타냈다. 그리고 높은 농축계수까지 여과 실험을 진행했음에도 불구하고 낮은 여과플럭스의 감소를 나타냈으며 1차 증류수를 이용한 짧은 시간 동안의 물리세정만으로 최소 90% 이상의 높은 여과 플럭스 회복율을 나타냈다. 따라서 하수처리수 재이용을 위한 공정으로 막증발법의 적용이 충분히 가능할 것으로 판단된다.

• 자원리싸이클링
• /
• 제19권1호
• /
• pp.57-65
• /
• 2010

최근, 인쇄회로기판 제조공정으로부터 유가자원을 회수하고자 하는 연구가 활발히 진행되고 있다. 인쇄회로기판의 드릴가공 받침대로 사용한 후 폐기되는 백보드 소재활용과 소형화, 고 신뢰성화에 따른 유가금속인 금 회수가 필수적이다. 특히 이동통신용 전자부품의 핵심소재로 사용되는 인쇄회로기판부품에는 최소 0.03 ${\mu}m$에서부터 최대 50 ${\mu}m$ 두께로 금이 도금되어 있다. 금, 원자재, 약품 값 폭등으로 생산현장의 유가자원 활용이 중요한 과제로 대두되면서 유가자원 활용을 위한 경쟁이 가속화되는 추세다. 본고에서는 인쇄회로기판 제조공정에서 발생하는 폐백보드 및 금의 회수에 대한 기술동향을 제공함으로써 유가자원 활용 산업발전에 기여하고자 하였다.

• 전자공학회논문지B
• /
• 제29B권2호
• /
• pp.9-17
• /
• 1992

In recent years, object-orientation is rising to notice as a new paradigm for developing software. This paper suggests the diagramming technique and a tool for developing C++ program effectively. This technique can represent the modularity and the interactions of classes definitely by emphasizing the characteristics of classes of C++. It can do the direct mapping from the logical idea to the physical screen image, so programmers can reuse the design resources in design phase as well as transforming the resources into chode in the implementation phase.

• 환경위생공학
• /
• 제12권3호
• /
• pp.111-119
• /
• 1997

We met the continued population growth, contamination of both surface and groundwaters, deficiency of water resources, and increase of water demand. Wastewater reclamation and reusing system are important facilities in water resources planning aspect. The required water quality for reclamed wastewater varies with each application. This study was conducted to examine the possibilities of the wastewater reclamation and reusing on milk manufacturing wastewater. Biofiltration could reduce the COD$_{Cr}$, NH$_{3}$-N. Turbidty was reduced highly by coagulation. In conclusion, we identified the possibilities of wastewater reclamation and reusing on milk manufacturing wastewater's by biological activated carbon filter.

• 한국자원리싸이클링학회:학술대회논문집
• /
• 한국자원리싸이클링학회 2005년도 춘계임시총회 및 제25회 학술발표대회
• /
• pp.186-190
• /
• 2005