• 한국상하수도협회지
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• s.16
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• pp.96-103
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• 2006

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.3
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• pp.5-14
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• 2018

This study investigated the effect of concentrate of membrane filtration of sewage reuse facilities on bioreactor's microorganisms in sewage treatment facility, and concentrate was analyzed, oxygen uptake rate and continuous activated sludge experiment were performed. As a results, the concentration of organic matter and TP concentration in concentrate was closely related to the concentration of SS and the concentration of ionic substances in concentrate was higher in order of $Cl^-$ > $Na^+$ > $Ca^{2+}$ > $K^+$ > $Mg^{2+}$ > $F^-$. And the analysis value of analytical items was greatly fluctuated according to sampling time of concentrate. Result of OUR test according to the mixing ratio of concentrate to sewage, it was found that the concentrate acts as an organic matter in the activated sludge microorganism and it increases with the increase of the concentrate mixing ratio. As a result of continuous activated sludge experiment, MLSS concentration, organic removal efficiency and TN removal efficiency gradually decreased with increasing concentrate mixing ratio. Based on the experimental results, expected mixing ratio of concentrate to affect the treatment efficiency of activated sludge is 25%.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.77-85
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• 2002

The objective of this study was to evaluate the performances of the ASBR under critical conditions of solid-liquid separation, caused by extremely high solids concentration, for wider application of the ASBR to various wastes. The ASBRs and completely-mixed daily-fed control runs were operated using a municipal mixed sludge at 35$^{\circ}C$ and 55$^{\circ}C$. Conversion of completely-mixed daily-fed reactor to sequencing batch mode and changes in HRT of all ASBRs were easily achieved without adverse effect, regardless of digestion temperature. Solids accumulation was remarkable in the ASBRs, and directly affected by settleable solids concentration of the feed sludge. Noticeable difference in solids-liquid separation was that flotation thickening occurred in the mesophilic ASBRs, while gravity thickening was a predominant solid-liquid separation process in the thermophilic ASBRS. Solids profiles at the end of thickening step dramatically changed at solid-liquid interface, and slight difference in solids concentrations was observed within thickened sludge bed. Organics removals based on subnatant or supernatant after thickening always exceeded 80% in all reactors. Thickened sludge volume and gas production of the ASBRs affected mutually. Gas production increased as thickened sludge accumulated, and continuous gas evolution during thickening could cause thickened sludge to expand or resuspend. Thickened sludge volume exceeding a predetermined withdrawal level resulted in loss of organic solids as well as biomass during withdrawal step, leading to decrease in gas production ind SRT. Such an adverse mutual effect was significant in gravity thickening, while it was not sensitive in flotation thickening. Changes in organic loading had no significant effect on organic removals and gas production after build-up of solids in the ASBRs.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.641-648
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• 2009

The study presents sewage sludge flotation and thickening efficiencies which changes chemical conditioning and mixing conditions using a flotation thickening system with a microbubble generating pump. Flotation and thickening of sewage sludge are shown to significantly influence kinds of coagulants more than Gt values. It is found that the flotation and thickening efficiencies for kinds of coagulants follows the order: $Al_2(SO_4)_3$ < PSO-M < $Fe_2(SO_4)_3$. We shows that the flotation thickening system(1.6 $m^3$/d) could be continuously operated during two hours on operation conditions in the lab-scale experiments. Sludge thickening efficiency in the A/S ratio of 0.029 - 0.019 mL/mg was found to be very efficient, reaching to 300.0~335.7%.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.69-73
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• 2013

This study is about the secondary concentration technology using electrodialysis process for minimum discharge and maximize recovery ratio from seawater desalination by reverse osmosis process. The experimental method adopted the constant voltage driving method and, concentrated/desalination volume capacity ratio changes, voltage changes and electrolyte types. Multi-ion membrane is used, aiming to derive conditions to minimize the TDS concentration of desalination water, to minimize the volumes of secnodary concentraion water and minimizing the power efficiency. The results of this study are as follows. The optimal ratio of concentraion/desalination volume is 1:5, the final TDS concentration of desalinated water is 5.32g/l, the final secnodary concentrated water salinity is 17.07% and electric energy demands of desalinated water is $16.74kWh/m^3$.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.743-748
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• 2009

Chemical sludge conditioning is widely used to improve the dewatering efficiency. It is treated with commonly used conditioners, and then thickened and dewatered with a mechanical device. This paper aims to examine the flotation and thickening efficiencies of sewage sludge for conditioning conditions, such as unaerobic storage time, kinds of coagulant and dosages, and flotation conditions, such as sludge concentration and A/S ratio, using an dissolved air flotation apparatus. Experimental results showed that the specific surface area and specific resistance to filtration (SRF) were significantly increased and the flotation and thickening efficiencies were decreased with anaerobic storage time. However, the flotation and thickening efficiencies faintly decreased in sewage sludges conditioned as $Al_2(SO_4)_3$, $Fe_2(SO_4)_3$, and PSO-M. Flotation and thickening efficiencies in conditioned sewage sludge could be sustained up to 96% at A/S ratio of 0.01 mL/mg or over.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.38-40
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• 1995

분리막공정을 폐수처리에 적용시 적용되는 각 폐수의 특성과 조건에 따라 공정의 안정성 및 경제성에 많은 영향을 받게 된다. 특히 폐수에 대한 농축도는 공정의 경제성과 밀접한 관계를 갖고 있는 중요한 인자이다. 폐수중에 염류 및 난분해성 유기물의 농도가 높을 경우 최종 처리수의 양을 줄이지 않으면 추가로 농축수에 대한 처리비용이 증가하기 때문에 폐수에 대한 분리막의 농축특성을 실험을 통하여 충분히 고려하여야 한다. 난분해성 폐수의 일종인 염료폐수는 고농도의 유기물과 높은 염류를 함유하고 있어 분리막공정을 이용하여 처리시 농축도의 증가와 함께 폐수의 특성변화로 막의 성질을 변화시킬 수도 있다. 더불어 과포화된 무기이온성분에 의하여 막표면에 scale을 유발시킬 수 있으므로 농축에 따른 적절한 무기이온성분의 제거는 농축도를 높이는 중요한 인자라고 볼 수 있다. 본 연구에서는 2가 이온에 대한 선택적 배제가 가능한 nanfiltration계열의 분리막을 이용하여 염료폐수를 대상으로 처리효율, cold crystallization공정을 응용한 농축실험 및 세척효과에 관하여 연구하였다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.483-484
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• 2003

일반적으로 싸이클론은 여러 산업공정에서 입자의 분리/제어를 위해서나 대기 중의 입자상 물질을 측정하기 위해서 많이 쓰여 왔다. 하지만 싸이클론은 작은 입자에 대해서는 효율이 낮고, 완만한 포집 효율 곡선을 가지고 있기 때문에, 고효율을 얻거나 이상적인 효율 곡선을 얻는 방법에 대해서 많은 연구가 집중되었다. 최근에는 입자를 분리/포집하기 위해서 싸이클론을 사용하는 것뿐만 아니라, 일정 크기의 입자를 분리하고 농축하기 위해서 가상 싸이클론(virtual cyclone)을 사용하는 연구가 진행되고 있다. (중략)

• Journal of Energy Engineering
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• v.25 no.4
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• pp.1-6
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• 2016

Seawater desalination plants generally have two inherent problems which stem from energy inefficiency and desalination concentrate management. The former has been somewhat resolved thanks to the innovative methods in utilizing new and renewable energy resources whereas the latter still has much issues to be dealt with. This paper introduces the application of a desalting process for the disposal of desalination concentrate (especially, Mg) and to improve its cost effectiveness of a MVR seawater desalination plant built in Jeju. Principal component analysis on the desalination concentrate has revealed a steady reduction of Mg with the application of the desalting process verifying its functional reliability. Also, it was found that our MVR seawater desalination plant is not only energy efficient but also could be effectively applied for the dual purpose of fresh water production and concentrate management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.136-143
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• 2016

To provide a type approval test for Ballast Water Treatment System (BWTS) of United States Coast Guard (USCG) Phase-II, this study examined the concentrating efficiency of nets for ${\geq}10{\mu}m$ and ${\leq}50{\mu}m$ sized phytoplanktonic organisms using different mesh sized nets ($5{\mu}m$ or $7{\mu}m$), different injection methods (hand breaker as semi-continuous assessment or pump as continuous assessment), and different filterability for the water volume. As a result of the t-test, the net concentrated efficiency between $5{\mu}m$ and $7{\mu}m$ mesh size was not significant (p > 0.05). The difference in the net concentrated efficiency for filtered natural water volume was not significant (p > 0.05). On the other hand, the Chl.a concentration in the continuous water injection method was significantly (p < 0.05) higher than that of semi-continuous water injection (t-test: t: -4.058). In the natural phytoplankton community, a total of 36 species were identified, including Bacillariophyta (17 species), Dinophyta (15 species), Euglenophyta (1 species), Dictyochophyta (2 species), and unidentified taxa (1 species). Among them, diatom Pseudo-nitzchia spp. was remarkably dominant. In particular, the net concentrated efficiency in all assessments was underestimated to be approximately 20-25%, which was caused by the small size Pseudo-nitzchia spp.. A width size of these genus might have passed through the $5{\mu}m$ or $7{\mu}m$ mesh size of the net. Therefore, net concentrated efficiency is dependent on the size of the observed species in natural water. This issue should be considered when determining the net volume for the type approval test of BWTS.