• Journal of Environmental Science International
• /
• v.7 no.6
• /
• pp.867-873
• /
• 1998

Laboratory study was conducted to provide basic data for operating anaerobic sequencing batch reactor(ASBR) process for treatment of nightsoil. The experiments were concerned with digestion characteristics, settleabiltity and dewaterability of digested sludge in ASBR system. Completely-mixed dally-fed control reactor without solid-liquid separation step was also operated to evaluate the baseline performance since the nature of nightsoil was changed with time. In all case, gas production from the ASBR shows 1.3 to 1.44 times higher than that from control, in spite of almost similar trend in organics removal. During thickening period, remarkable decrease in surface settling velocity was observed at the ASBRs compared with the control. In case of the ASBR run, flotation of mixed digested sludge was not occurred. Also, ultimate thickened volume of ASBRs increased 1.2~1.5 times compared with control. Dewaterability of digested sludge without conditioning decreased when the completely-mixed daily-fed reactor for ASBR run was converted to the ASBR. However, improvement of dewaterability of digested sludge from the ASBRs was observed as a result of addition of FeCl$_3$ to digested sludge for conditioning.

• Resources Recycling
• /
• v.13 no.3
• /
• pp.19-26
• /
• 2004

In order to use the mine tailing which was generated in the flotation process of scheelite ore into the raw material of ordinary portland cement, the characteristics of the prepared cement clinker was investigated. Scheelite mine tailing is composed of 68.8% of $SiO_2$, 8.6% of $Al_2$$O_3$, 10.8% of $Fe_2$$O_3$, 5.0% of CaO, respectively. It exists as $\alpha$-quartz, muscovite, clinochlore and has 8.0% of 88 $\mu\textrm{m}$ residue. When LSF, SM, and IM of the raw materials (such as limestone, convertor slag, fly ash, and mine tailing) are 91.0, 2.60, and 1.60, respectively, the burnability index of the raw materials is 50.7, the crystal size of $C_3$S and $\beta$-C$_2$S in the prepared clinker is 15∼35$\mu\textrm{m}$, and about 3.8% of scheelite mine tailing can be used as raw material.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2002.05a
• /
• pp.15-16
• /
• 2002

라이너지는 대부분의 원료물질을 고지로부터 얻고 있는 친환경적 상품이 다. 그러나 고지를 원료로 사용함에 따라 많은 문제가 발생하게 된다. 그중 원료와 함께 유입되는 다양한 종류의 오염물질로 인하여 기인되는 스틱키는 강도를 저하시킬 뿐 아니라 얼룩 및 반점을 형성하여 제품의 질을 떨어뜨리 고, 또한 설비를 오염시켜 수명 단축 및 세척에 의한 조업중단 등 생산성 저 하를 가져온다. 이러한 문제는 초지기의 대형화와 고속화, 용수조건의 악화 및 고지 재활용율 증가 등의 이유로 더욱 커지고 있다. 본 논문에서는 라이너지 생산공정의 가운데 지료조성공정의 매크로 스틱 키 정량분석을 통하여 전반적인 분포를 조사하였다. 그 결과 매크로 스틱키 는 스크린과 클리너를 통해 다량 제거되고, 공정상의 기계적 에너지에 의해 더욱 미분화되어 제어가 어려운 마이크로 스틱키로 진행되고 있음을 확인하 였다. 또 지료 분급을 위하여 설치된 플로테이션 설비는 기존의 정선설비인 스크린과 클리너에서 제거되기 어려운 마이크로 스틱키를 제거할 수 있음을 확인하였다. 본 연구에서는 실제 공정의 마이크로 스틱키 정량이 가능한 설비를 제작 하였다. 제작된 설비는 마이크로 스틱키의 정량 뿐만 아니라 환경의 변화에 따른 마이크로 스틱키의 침착성 변화를 볼 수 있도록 하였고, 또한 현장조건 에 적합하도록 다량의 지료분석과 손쉬운 작동이 가능케 하였다. 제작된 마 이크로 스틱키 정량설비를 이용하여 현장 플로테이션 공정을 대상으로 마이 크로 스틱키를 정량한 결과 리젝트의 지료에서 더 많은 량의 마이크로 스틱 키가 존재함을 확인하였다. 이는 소수성의 마이크로 스틱키가 기포와 함께 리젝트로 배출되고 있음을 보여주고 있으며, 또한 3종의 분급된 지료에서 와 이어상에서 탈수된 각각의 백수를 분석함으로써 백수 재활용에 따른 마이크 로 스틱키의 농축현상올 밝혔다. 플로테이션 과정중에 마이크로 스틱키의 거동 파악과 제어를 향상시키기 위하여 MCC를 이용하여 준비된 마이크로 스틱키 모텔물질을 이용하여 실험 실적 부유부상 실험을 실시하였다. 이를 통하여 플로테이션 공정의 마이크로 스틱키 제어 최적화 방안과 고농도의 마이크로 스틱키를 함유한 지료의 처 리를 방안을 검토하였다.

• Resources Recycling
• /
• v.24 no.4
• /
• pp.56-60
• /
• 2015

Fine particle classification was performed using products obtained from primary classification process after flotation for efficient application of tailing. The cut size increased with decreasing input pressure from 0.1 MPa to 0.3 MPa and increasing pulp density from 5% to 15% using 2-inch hydrocyclone. The median sizes of overflow and underflow were $6.56{\mu}m$ and $55.45{\mu}m$, respectively at 0.3 MPa with 5% pulp density. The imperfection became closed to ideal separation with increasing the pulp density and decreasing the input pressure. The water content decreased with increasing the pulp density, but the effect of input pressure could be ignored. The water content of underflow was 27.9% at 0.3 MPa with 15% pulp density.

• Resources Recycling
• /
• v.8 no.5
• /
• pp.51-58
• /
• 1999

The sbdy iwestlgaled ihc propa-ties of Lhe dust\ulcorner rrom fe~~oallomya ~~ufacturTeh. e chemical composition, cornpasitlon material, p d c l e sire md shapes of the bulk dust, sired dust and magnetically separated durl were mvesligaled. As the re\ulcornerulL, we suppose that the dust from &gh Carbon Fenama~~gunesMc anuiact~vingP rocess is not sufiicient as solulce material of Mn because of ale low Mn canlenl (13.5%) and complicaled composition mate~ial. The dust from Bug F!lter or AOD Proccss is mi~inlym ade up of 0.2-2 pm Mn30, (Hausmam~iu)p iutlde in spherical shape and thc Mn content is 63.190.The dust from Cooler of AOD Process is inninly made up of coarse Ca(O1-Or)zM. n,FeyO,, SiO, and fine Mn30d.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.4 no.4
• /
• pp.79-93
• /
• 1984

The dissolved air flotation(DAF) has been shown to be efficient process for the removal of algae ftom water. The efficiency of DAF can be affected by the volume ratio of pressurized liquid to sample, the pressure pressurized liquid, the contact time, the appropriate coagulant and its amount, the water temperature, the turbulence of reactor, the bubble size and rising velocity etc. The purpose of this paper is to compare the practical bubble rising velocity with the theoretical one, to investigate the adhesion phenomenon of bubbles and floc, and the influence of bubble size and velocity upon the process. The results through theoretical review and experimental investigation are as follows: Ives' equation is more suitable than Stokes' equation in computation of the bubble rising velocity. The collection of bubble and algae floc is convective collection type and resulted from absorption than adhesion or collision. The treatment efficiency is excellent when the bubble sizes are smaller than $l00{\mu}m$, and the turbulence of reactor is small. In the optimum condition of continuous type DAF the volume ratio of pressurized liquid to sample is 15%, the contact time in reactor is 15 minutes, the pressure of pressurized liquid is $4kg/cm^2$ and the distance from jet needle to inlet is 30cm.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.6
• /
• pp.567-572
• /
• 2005

In this study, a lab-scale test was performed to apply the ozone process in drinking water treatment plant using dissolved ai, flotation(DAF). The kinetic study on the ozone decay and hydroxyl(OH) radical formation was investigated by several parameters, such as I.D(Instantaneous ozone demand), $k_c$(ozone decomposition rate), ozone-Ct and OH radical-Ct. Ozonation of several target waters, such as raw water, DAF treated water and filtrate, was conducted to select the optimum position and dosage of ozone process. The highest value of Ozone-Ct and OH radical-Ct was observed at DAF treated water at initial run time($0{\sim}30\;min$). From the results of ozonation, the intermediate ozonation was proposed as the optimum position and the effective dose of ozone was determined to be $1{\sim}2\;mg/L$.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.22 no.3
• /
• pp.68-75
• /
• 2014

Soluble nitrogen produced from anaerobic digestor is able to have a strong influence on the effluent water quality of municipal wastewater treatment plants during a winter season in particular. The modeling results using the GPS-X simulation software shows that the soluble nitrogen concentration generated from the anaerobic digestor is 214.1 mg/L in the return flow and 6.2 mg/L in the inflow of the primary settler higher than those in nonexistence of the anaerobic digestor, respectively. In the case of using a separation process (flotation thickener) in order to treat the return flow from the sludge treatment system, the soluble nitrogen concentration in the effluent from the separation process and in the inflow of the primary setter could be 6.0 mg/L higher and 0.7 mg/L lower than those of nonexistence of the process, respectively. The modeling results propose the need of the equipments to be able to remove the soluble nitrogen ($NH_3-N$) produced from the digestor in the improvement projects of anaerobic digestor in municipal wastewater treatment plants.

• Journal of Soil and Groundwater Environment
• /
• v.18 no.3
• /
• pp.93-108
• /
• 2013

This study is aimed to prepare the effective detail survey methods(Phase II) of abandoned metal mines through the contamination assessment for mine types and facilities in the abandoned metal mine areas. The study sites of 12 abandoned mines are located in Gyeonggi-do and Gangwon-do and those were chosen among 310 sites that the Phase II survey was conducted from 2007 to 2009 after considering the results of Phase I for abandoned mines scattered all over the country. 12 study sites were classified into four types; Type I sites only have pit mouth. Type II sites have pit mouth and mine-waste field. Type III sites have pit mouth and tailing sorting field. Type IV sites have pit mouth, tailing sorting field and concentrator(s). In forest land, paddy soil and farm land of Type I, As and Cd were showed average concentration, and Cu and Pb were high on the pit mouth area in one mines where the pit mouth was developed within 500 m. In the mines of Type II, Cu and Pb were showed average concentration too, but As and Cd were slightly high in pit mouth and mine-waste field. The mines of Type III which had grinding particle process through physical separation milling or hitting showed similar tendency with Type II. However, mines of Type IV pit mouth, mine-waste field and showed various results depending on defining the contamination sources. For example, if contamination source was pit mouth, the mixed results of Type I, II, II were showed. In tailing sorting field which was regarded as the most important source and having high mobility, however, if there were no facilities or it was difficult to access directly, field sampling was missed occasionally during phase I and phase II survey. For that reason, the assessment for tailing sorting field is missed and it leads to completely different results. In the areas of Type I mines, the concentration of heavy metals exceeded precautionary standards of soil contamination or not within 1,000 meters of pit mouth. Nickel(Ni) was the largest factor of the heavy metal contamination in this type. The heavy metals except Arsenic(As) were shown high levels of concentration in Type II areas, where pit mouth and mine-waste field were operated for making powder in upriver region; therefore, to the areas in the vicinity of midstream and downstream, the high content of heavy metals were shown. The tendency of high level of heavy metals and toxic materials contained in flotation agent used during sorting process were found in soil around sorting and tailing field. In the abandoned-pit-mouth area, drygrinding area and tailing sorting field area, the content of Cupper(Cu) and Zinc(Zn) were higher than other areas. Also, the contaminated area were larger than mine reclamation area(2,000 m) and the location of tailing sorting field was one of the important factors to estimate contaminated area.

• Journal of Conservation Science
• /
• v.28 no.3
• /
• pp.235-245
• /
• 2012

Nondestructive deterioration diagnosis has been carried out for the former ore dressing plant of the Yongwha mine in Yeongyang (Registered Cultural Property No. 255). Deterioration rates about organic contaminant and soil of the upper part (7 to 13 layer) indicate higher than the lower part (1 to 6 layer) of the ore dressing plants. By contrast, deterioration rates such as crack, break out and discoloration of the lower part indicate very higher than the upper part. It is estimated that the plants of the lower part that mechanical and chemical process had been done for flotation were damaged severely by physicochemical weathering with reaction of concrete and chemical solution. As results of ultrasonic velocity measurement, average p-wave velocity of plants were measured 2,462m/s (compressive strength $529kgf/cm^2$). As for the analytical results of surface contaminants and soil compositions using P-XRF, they were identical with major elements (Cu, Zn, Pb, Fe and As) of ore minerals from the Yongwha mine. Therefore, the ore dressing plant should be treated by phytoremediation with conservation because heavy metals could impinged upon plants and natural environment.