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

• 펄프종이기술
• /
• 제29권3호
• /
• pp.34-42
• /
• 1997

This study was carried out to investigate the proper cooking conditions of soda-anthraquinone and alkaline sulfite-anthraquinone pulping of rice-straw, and get basic data f9r the use of rice-straw chemical pulp through the test of characteristics and physical properties of pulps made in the various cooking conditions From the experimental results , we can conclude as follows. In the soda-anthraquinone pulping of rice-straw, the optimum cooking conditions were 60 min. at $150^{\circ}C$ in the amount of caustic soda of 20% with the addition of anthraquinone(0.05%). And total yield, Kappa No. and brightness of pulp made in the condition above mentioned were 41.9%, 7.7 and 51.1 respectively. In the alkaline sulfite-anthraquinone pulping of rice-straw, the proper mixing ratio of cooking chemical(caustic soda : sodium sulfite) was 50:50. And the optimum cooking conditions were 60 min. at $150^{\circ}C$ in the amount of cooking chemical of 20% with the addition of anthraquinone(0.05%). At that time, the total yield, Kappa No, and brightness of pulp were 50.1%, 9.1 and 40.2 respectively. As a result, the alkaline sulfite-anthraquinone pulping was superior to the soda-anthraquinone pulping in the aspect of yield, but inferior in the viewpoints of Kappa No. and brightness. For the comparison of qualities of pulps made in the various cooking methods and conditions, the physical properties of four sorts of pulps were tested. As a result, soda-anthraquinone pulps were superior to alkaline sulfite-anthraquinone pulps in the various strengths excluding tear strength and brightness. On the other hand, pulps made in the condition of addition of cooking chemical of 20% were superior to pulps in the dosage of 15% in the aspects of all the strengths and brightness.

• 자원리싸이클링
• /
• 제25권6호
• /
• pp.98-104
• /
• 2016

본 연구의 목적은 호주산 저품위 동광을 부유선별하여 정광으로 회수하고자 할 때, 최적의 부유선별 조건을 얻고자 하는데 있다. 본 연구에서는 저품위 동광의 파분쇄 및 분급에 의해 선별에 적절한 입자크기의 시료를 얻은 다음, 이를 대상으로 부유선별 시 포수제, 활성제, 억제제의 첨가량 및 광액의 pH 변화가 부선효율에 미치는 영향을 조사함으로써 품위가 향상된 정광을 얻고자 하였다. 본 연구실험결과 얻은 최적의 부유선별 조건은 광액산도 pH9.0, 활성제 500 g/t $CuSO_4{\cdot}5H_2O$, 포수제 500 g/t K.E.X, 억제제 1500 g/t $Na_2SO_3$, 광액농도는 25 wt.% 이었다. 최적조건하에서 얻은 정광중의 동 품위 및 회수율은 각각 4 wt.%와 65 wt.% 정도이었고 대부분 철 성분을 함유한 광물 이었다.

• Advances in environmental research
• /
• 제9권2호
• /
• pp.135-150
• /
• 2020

Many industries, such as textiles, chemical refineries, leather, plastics and paper, use different dyes in various process steps. At the same time, these industrial sectors are responsible for discharging contaminants that are harmful and toxic to humans and microorganisms by introducing synthetic dyes into wastewater. Of these dyes, methylene blue dye, which is classified as basic dyes, is accepted as a model dye. For this reason, methylene blue dye was selected in the study and its removal from the water was studied. In this study, two efficient biosorbents were developed from chitosan and sunflower waste, an agro-industrial waste and modified using iron nanoparticles. The biosorption efficiency was evaluated for methylene blue (MB) dye removal from aqueous solution under various parameters such as treating agent, solution pH, biosorbent dosage, contact time, initial dye concentration and temperature. We investigated the kinetic properties of dye removal from water for Chitosan-Sunflower (CS), Chitosan-Sunflower-Nanoiron (CSN). When the wavelength of MB dye was spectrophotometrically scanned, the maximum absorbance was determined as 660 nm. For the core shell biosorbents we obtained, we found that the optimum time for removal of MB from wastewater was 60 min. The pH of the best pH was determined as 5 in the studied pH. The most suitable temperature for the experiment was determined as 30℃. SEM-EDAX, TEM, XRD, and FTIR techniques were used to characterize biosorbents produced and modified in the experimental stage and to monitor the change of biosorbent after dye removal. The interactions of the paint with the surface used for removal were explained by these techniques. It was calculated that 80% of CS and 88% of CSN removed MB in optimum conditions. Also, the absorption of MB dye onto the surface was investigated by Langmiur and Frendlinch isotherms and it was determined from the results that the removal was more compatible with Langmiur isotherm.

• 상하수도학회지
• /
• 제35권4호
• /
• pp.285-292
• /
• 2021

Osmotic power is to produce electric power by using the chemical potential of two flows with the difference of salinity. Water permeates through a semipermeable membrane from a low concentration feed solution to a high concentration draw solution due to osmotic pressure. In a pressure retarded osmosis (PRO) process, river water and wastewater are commonly used as low salinity feed solution, whereas seawater and brine from the SWRO plant are employed as draw solution. During the PRO process using wastewater effluent as feed solution, PRO membrane fouling is usually caused by the convective or diffusive transport of PRO which is the most critical step of PRO membrane in order to prevent membrane fouling. The main objective of this study is to assess the PRO membrane fouling reduction by pretreatment to remove organic matter using coagulation-UF membrane process. The experimental results obtained from the pretreatment test showed that the optimum ferric chloride and PAC dosage for removal of organic matter applied for the coagulation and adsorption process was 50 mg/L as FeCl₃ (optimum pH 5.5). Coagulation-UF pretreatment process was higher removal efficiency of organic matter, as also resulting in the substantial improvement of water flux of PRO membrane.

• 셀메드
• /
• 제11권3호
• /
• pp.15.1-15.9
• /
• 2021

The chemical constitution of a drug has been accepted as an important basis for pharmacological action in Unani medicine. Various dosage forms have been developed on this concept, such as decoctions (Joshanda), infusions (Khesanda), extract (Rub / Usara), and syrup. Zarawand Mudaharaj (ZM.) / Aristolochia rotunda L. root was subjected to extraction process using Soxhlet's apparatus by using Response Surface Methodology (RSM) to design the number of random runs of the extracts with variation in the factors of temperature, the concentration of ethanol in water, time for extraction, for optimizing and maximizing the yield concentration. The data obtained, was analyzed with regression equation and ANOVA two-way summary to interpret the interaction of the factors for yield maximization. Minitab version 18 was used to design and analyze data. Validation of the optimum conditions for maximum yield of the whole extract of ZM. Root was carried out by re-run of the extract using the optimized conditions. The maximum yield percentage thus obtained using RSM was 20.87% whereas using these optimum conditions 21.35 % yield was obtained thereby validating the method. The association between the response functions and the process variables was identified by a three-factor recorded Box-Behnken design. In the present study RSM is used because itis a cheap and affordable method to optimize maximum yield percentage which may be reliably used by researchers. The study set in the surface conditions for ZM. root extraction by the Soxhlet apparatus for maximizing the yield percentage.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제9권6호
• /
• pp.523-527
• /
• 2004

Recombinant Saccharomyces cerevisiae expression systems were developed to pro­duce a novel human anti-angiogenic protein called LK8, an 86 amino-acid kringle fragment pro­tein with three disulfide linkages. Galactose-inducible LK8 expression plasmid was constructed, and LK8 production levels by four S. cerevisiae strains were compared in order to select an op­timal host strain. S. cerevisiae 2805 was the most efficient among the strains tested. Elevating the LK8 gene copy number through multiple integration using 8-sequences as target sites re­sulted in more than a two-fold increase in the LK8 production level compared with the plasmid­based expression system. The maximum LK8 protein concentration of 25 mg/L was obtained from batch cultivation of the yeast transformant that harbors 16 copies of the LK8 gene. In con­clusion, the strain integrated with the multiple LK8 gene secreted the protein with relatively high yield, although, the increased LK8 gene dosage over 11 copies did not lead to further en­hancement in batch cultivations.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• 제2권2호
• /
• pp.139-148
• /
• 1998

The charge densities of humic acid and humic extract have been determined by back titration using spectrophotometry as the method of end point detection and several cationic polymers of different charge density(copolymers of acylamide and dimethylaminoethylacrylate and polydiallyidimethylammonium chloride, PDDA), and a cationic indicator o-toluidine blue(o-Tb). The charge densities of humic acid and humic extract obtained depend on the charge densities of cationic polymers used. When the polymers of lower charge density are used, lower apparent charge density values are obtained, but for polymers of high charge density(above 2.5 meq/g), the measured values are almost identical, but also are nearly the same as that obtained for PDDA which has a high charge density(about 6 meq/g). For polymers of lower charge density, it is considered that the optimum dosage does not correspond to 1 :1 charge neutralization between anionic and cationic groups. Polymers of high charge density should be used in order to achieve a complete charge neutralization. As humic acid and humic extract are dissociable acids, their ionization is heavily pH dependent and so higher charge density values are obtaines with increasing pH.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2004년도 학술.기술논문발표회
• /
• pp.61-64
• /
• 2004

This study is to investigate the engineering and shrinkage properties of concrete incorporating shrinkage reducing agent(SRA) and expansive additive(EA) in order to reduce shrinkage of concrete. According to results, as for the properties of fresh concrete, increase in, SRA and EA content leads to reduce the fluidity but to increase the air content, and as for setting time, there is little difference. For strength properties, it decreased with an increase in SRA dosage and increased up to 5% of EA content. For the properties of drying shrinkage, it shows decline tendency with an increase in SRA and EA content reiteratively. It alto reduces significantly with the combination of SRA-EA systems due to the combined effect of the admixture. In the scope of this paper, it is found that the use of SRA with 0.5％ and EA with 5% has optimum effects on the various properties of concrete. And under the combination of SRA and EA, it can reduce drying shrinkage about 37%.

• Journal of Forest and Environmental Science
• /
• 제14권1호
• /
• pp.101-111
• /
• 1998

본 연구에서는 우유팩을 이용하여 재생용 화장지를 만드는 제지공장의 제지폐수를 이용하여 폐수의 침강특성 및 SS, $BOD_5$, 제거 효율을 검토하고, Jar-tester를 이용하여 급속교반시간, 완속교반 시간에 따른 탁도, SS, S-$BOD_5$ 및 최적 응집제 주입량을 결정하였다. 각종 응집제 첨가 및 침강 특성에 의한 탁도제거의 효율을 측정하였다. 적정 응집제 첨가량, 급속교반 및 완속교반의 시간에 따른 처리 효율의 이론식을 제시하였다. 또한 응집제 Polyaluminium chloride(PAC) 및 Aluminium sulfate의 응집 비교 실험을 행하였다.