• 상하수도학회지
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• 제32권5호
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• pp.371-379
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• 2018

The lack of seed sludges for Ammonium Oxidizing Bacteria (AOB) and slow-growing ANaerobic AMMonium OXidation (ANAMMOX) bacteria is one of the major problem for large-scale application. In this study, $24m^3$ of single-stage SBR (Sequencing Batch Reactor) was operated to remove nitrogen from reject water using AOB and ANAMMOX bacteria cultivated from activated sludge in the field. The ANAMMOX activity was found after 44 days of cultivation in the ANAMMOX cultivation reactor, and then $0.66kg\;N/m^3/d$ of the nitrogen removal rate was achieved at $0.78kg\;N/m^3/d$ of the nitrogen loading rate at 153 days of cultivation. The AOB cultivation reactor showed $0.2kg\;N/m^3/d$ of nitrite production rate at $0.4kg\;N/m^3/d$ of nitrogen loading rate after 36 days of operation. The cultivated ANAMMOX bacteria and AOB was mixed into the single-stage SBR. The feed distribution was applied to remove total nitrogen stably in the single-stage SBR. The nitrogen removal rate in the single-stage SBR was gradually enhanced with an increase of specific activities of both AOB and ANAMMOX bacteria by showing $0.49kg\;N/m^3/d$ of the nitrogen removal rate at $0.56kg\;N/m^3/d$ of the nitrogen loading rate at 54 days of operation.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2004년도 International Conference Current Challenges and Advances in Environmental Health
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• pp.51-62
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• 2004

Lime based stabilization/solidification (S/S) can be an effective remediation alternative for the immobilization of arsenic (As) in contaminated soils and sludges. However, the exact immobilization mechanism has not been well established, Based on previous research, As immobilization could be attributed to sorption and/or inclusion in pozzolanic reaction products and/or the formation of calcium-arsenic (Ca-As) precipitates. In this study, suspensions of lime-As were studied in an attempt to elucidate the controlling mechanism of As immobilization in lime treated soils. Aqueous lime-As suspensions (slurries) with varying Ca/As molar ratios (1:1, 1.5:1, 2:1, 2.5:1 and 4:1) were prepared and soluble As concentrations were determined. X-ray diffraction (XRD) analyses were used to establish the resulting mineralogy of crystalline precipitate formation. Depending on the redox state of the As source, different As precipitates were identified. When As (III) was used, the main precipitate formation was Ca-As-O. With As(V) as the source, Ca4(OH)2(AsO4)2${\cdot}$4H2O formed at Ca/As molar ratios greater than 1:1. A significant increase in As (III) immobilization was observed at Ca/As molar ratios greater than 1:1. Similarly, a substantial increase in As (V) immobilization was noted at Ca/As molar ratios greater than or equal to 2.5: 1. This observation was also confirmed by XRD. The effectiveness of both As (III) and As(V) immobilization in these slurries appeared to increase with increasing Ca/As molar ratios.

• Journal of Microbiology and Biotechnology
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• 제16권2호
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• pp.232-239
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• 2006

The microbial activity and bacterial community structure of activated sludge reactors, which treated free cyanide (FC), zinc-complexed cyanide (ZC), or nickel-complexed cyanide (NC), were studied. The three reactors (designated as re-FC, re-ZC, and re-NC) were operated for 50 days with a stepwise decrease of hydraulic retention time. In the re-FC and re-ZC reactors, FC or ZC was almost completely removed, whereas approximately 80-87% of NC was removed in re-NC. This result might be attributed to the high toxicity of nickel released after degradation of NC. In the batch test, the sludges taken from re-FC and re-ZC completely degraded FC, ZC, and NC, whereas the sludge from re-NC degraded only NC. Although re-FC and re-ZC showed similar properties in regard to cyanide degradation, denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA gene of the bacterial communities in the three reactors showed that bacterial community was specifically acclimated to each reactor. We found several bacterial sequences in DGGE bands that showed high similarity to known cyanide-degrading bacteria such as Klebsiella spp., Acidovorax spp., and Achromobacter xylosoxidans. Flocforming microorganism might also be one of the major microorganisms, since many sequences related to Zoogloea, Microbacterium, and phylum TM7 were detected in all the reactors.

• Ocean Science Journal
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• 제40권2호
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• pp.91-100
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• 2005

Bioassay using the marine bacteria, Vibrio fischeri and rotifer, Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox(R) bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox(R) results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment.

• 한국물환경학회지
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• 제20권4호
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• pp.327-332
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• 2004

This study was carried out to examine the effect of gamma irradiation on the physico-chemical characteristics and ultimate anaerobic biodegradability of sewage sludge. The results found that the solubilization rates of SCOD in wasted activated sludge(WAS) and thickened sludge(T-S) with gamma irradiation of 3kGy were 8 times and 7 times greater than these of the raw WAS and T-S without the irradiation, respectively; each soluble concentration protein were 4 times and 3 times greater than these of the raw WAS and T-S; each soluble carbohydrate concentration was 8 times and 6 times greater than these of the raw WAS and T-S. The ultimate anaerobic biodegradabilities of WAS and T-S with gamma irradiation were 51 % and 50%, which corresponds to each 8% and 10% greater than these of the raw sludges. Approximately 83% and 81% of the each biodegradable substrates in the irradiated WAS and the T-S were degraded within 11 days with the first order decay rate coefficients, $k_1$ that ranged $0.143{\sim}0.164day^{-1}$ for WAS and $0.134{\sim}0.152day^{-1}$ for T-S. Based on the results, it can be concluded that when irradiated with gamma the solubilization of sewage sludge greatly increases resulting in substrates suitable for the subsequent biological treatment processes.

• 분석과학
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• 제10권6호
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• pp.395-402
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• 1997

시료의 매질에 따른 추출법의 문제점과 사용 가능성을 조사하기 위해 환경처 발행의 폐기물공정시험방법과 EPA 3050법을 비교 연구하였다. 이를 위해 sludge와 개펄 시료에 12종의 무기 priority pollutants(Cd, Cr, Cu, Pb, Ni, Zn, As, Sb, Se, Hg, Be, Tl)를 첨가하여 분석용 시료를 조제하고 AAS, HG-AAS, 그리고 ICP/MS를 사용하여 각 추출방법에 대한 대상 원소의 회수율, 상대표준편차 및 method detection limit를 측정하었다. EPA 3050법에 따라 추출한 경우 회수율이 좋지 않은 As, Sb, Se를 제외한 평균 회수율은 93%였다. 그러나 폐기물공정시험방법의 용출시험방법으로 실험한 경우는 전반적으로 회수율이 32%로 매우 좋지 않을 뿐만 아니라 시료의 매질에 의한 영향을 심각하게 받는 것으로 조사되었다.

• 자원리싸이클링
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• 제10권6호
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• pp.22-28
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• 2001

폐CRT의 재활용 공정에서 Panel 유리에 도포 된 형광체의 제거 시 발생하는 슬러지로부터 Y를 회수하는 연구를 수행하였다. HCI및 $HNO_3$을 사용하여 Y를 침출하였으며 산 농도, 침출온도, 침출시간, 광액농도가 침출율에 미치는 영향을 조사하였다. 또한 침출액으로부터 Y와 Pb를 침전 법으로 회수하는 실험을 행하였다 슬러지로부터 HCl 및 $HNO_3$에 의한 Y의 침출거동은 유사한 경향을 나타내었다. 광액농도를 280 g/L로 하여 $90^{\circ}C$에서 3.0M HCl및$ HNO_3$로 침출 하였을 때 시간에 따라 Y의 침출율은 증가하다가 40분 이상에서는 각각 93%, 90%로 일정한 침출율을 나타내었다. 침출액에 $H_2$$C_2$$O_4$를 첨가하여 Y를 회수하였으며 Pb는 $Na_2$$SO_4$를 가하여 $PbSO4$로 제거하였다.

• Journal of the Korean Wood Science and Technology
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• 제15권2호
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• pp.99-104
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• 1987

Fiber mats were made at various density levels, using fibers from papermill sludge, ricestraw and various mixtures of the two. The paper mill sludges were collected from Moorim Papermill Co, and Jeonjoo Papermill Co. They were soaked in the liquid sulfur compounds, sulfur-tall oil and sulfurpolyester compounds, and made into fiber-reinforced, sulfur-based composition board. Under optimum conditions of fiber mat preparation and saturation with molten sulfur and modified sulfur, the Young's moduls of the manufactured tiber-reinforced composition board are superior to those of conventional wood-based composition boards. For example, the moduli of elasticity of the composition board made from papermill sludge, with a density of 0.40gm/$cm^3$, were greater than 1,400,000psi as compared 800,000psi for high density hardboard(1.28gm/$cm^3$). The modulus of rupture of the best reinforced composition board manufactured was over 9000psi, comparable to 6000psi of high density hardboard. The proposed Bryant and Lee's theory, "Modified Rule of Mixtures" can be applicable to the nonoriented and short fibrous composition board, when it was modified from "Rule of Mixtures" established by Paul an Jones, and supplemented by Smith and Cox's theory, In the Bryant and Lee's theory of $E_c=\frac{1}{3}aE_fV_f+bE_mV_m$, the constants "a" and "b" for the composition boards made from papermill sludge and the mixtures of ricestraw and the sludge were identified to be in the ranges of 3.29~3.54 and -2.47~-2.80 respectively.

• 자원리싸이클링
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• 제23권3호
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• pp.61-70
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• 2014

주석은 땜납, 주석도금강판, 청동 합금, 투명전극용 타겟 및 화학첨가제 등에 널리 사용되고 있다. 최근 자원의 희소성 및 경제성으로 인해 주석 스크랩에 대한 재활용 기술이 연구되고 있다. 본 논문에서는 주석이 함유된 공정 스크랩, 슬러지, 도금 폐액 및 합금의 재활용 기술에 대하여 1970년부터 2013년까지 공개/등록된 한국, 미국, 중국, 일본, 유럽의 특허에 대하여 조사하였다. 특허는 키워드를 사용하여 수집하였으며, 기술의 정의에 의해 필터링 하여 연도, 국가, 출원인 및 기술에 따라 분석하였다.

• 한국환경보건학회지
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• 제27권2호
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• pp.17-21
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• 2001

The object of this study is to find out the characteristics of waste oyster shells and determine the proper dosage of powdered waster oyster shells as the conditioning agent for water treatment sludge dewatering process. The large amount of waste oyster shells which discharges from the oyster farming, occurs serious environmental hazards. However, oysters shell contain large amount(about 38% by weight) of alkaline minerals, such as calcium and magnesium and so on, this natural material is thought to have the petential ability as a good conditioning agent. The results of this study are as follows. The optimum condition for improvement of the water treatment sludge dewaterability is when 6 g of waste oyster shell powder added to 200$m\ell$ of water treatment sludge. At optimum condition, the solid contents can reach to 31.78% and the specific resistance of conditioned sludge is 0.16$\times$10$^{8}$ sec$^2$/g. However, exceeding the of powdered waste oyster shell is needed to get the effective result. Consequently, the waste oyster shell can be a recyclable material to improve the dewaterability of water treatment sludges.