• Membrane and Water Treatment
• /
• v.11 no.1
• /
• pp.1-10
• /
• 2020

An understanding of particle-particle interactions in filtration requires studying the detachment as well as the attachment of nanoparticles. Nanoparticles captured in a granular media filter can be released by changing the physicochemical factors. In this study, the detachment of captured silver nanoparticles (AgNPs) in granular media filtration was examined under different ionic strengths, ion type, and the presence or absence of natural organic matter (NOM). Filtration velocity and ionic strength were chosen as the physical and chemical factors to cause the detachment. Increasing filtration velocity caused a negligible amount of AgNP detachment. On the other hand, lowering ionic strength showed different release amounts depending on the background ions, implying a population of loosely captured particles inside the filter bed. Overall detachment was affected by ionic strength and ion type, and to a lesser degree by NOM coating which resulted in slightly more detachment (in otherwise identical conditions) than in the absence of that coating, possibly by steric effects. The secondary energy minimum with Na ions was deeper and wider than with Ca ions, probably due to the lack of complexation with citrate and charge neutralization that would be caused by Ca ions. This result implies that the change in chemical force by reducing ionic strength of Na ions could significantly enhance the detachment compared to that caused by a change in physical force, due to a weak electrostatic deposition between nanoparticles and filter media. A modification of the 1-D filtration model to incorporate a detachment term showed good agreement with experimental data; estimating the detachment coefficients for that model suggested that the detachment rate could be similar regardless of the amount of previously captured AgNPs.

• Journal of Environmental Health Sciences
• /
• v.31 no.4 s.85
• /
• pp.309-315
• /
• 2005

Volatile organic compounds (VOCs) and odor materials are major sources of air pollution in Ulsan city, where much chemical plants are located. Therefore, it is necessary to develop a new reactor which can remove VOCs and odor materials effectively and be equipped at the end of pipe easily. A modified reactor (bioscrubber trickling filter, BSTF), which have both characteristics of biofilter and bioscrubber, was developed and tested on its reactivity with several VOCs using two types of media, fiber and activated carbon 4- ceramic(A/C). It was observed that the removal efficiencies of several types of VOCs such as acetaldehyde, ethylalcohol, butanol, diethylamine and triethylamine were up to $95\%$ when they had about 100 ppm of initial concentration and 80 seconds of residence time. Good attachment of microorganisms to both media, where it is thought the reaction efficiency can be determined according to the amount of microorganisms attachment, observed with scanning electron microscopy(SEM). Initial pressure drops of the packed bed with both media were 229 $mmH_2O/m$ at A/C column and 670 $mmH_2O/m$, respectively. However, maximum pressure drop of fiber column during the operation was over 1,647 $mmH_2O/m$. Therefore, it was thought that the fiber material would not suitable to use in the local plant as a packed bed media.

• Polymer(Korea)
• /
• v.29 no.3
• /
• pp.288-293
• /
• 2005

Osmotic granule system which is one of the drug delivery systems has been developed to improve manufacturing process and other problems of tablet osmotic systems. It consists of water swellable seed layer, nifedipine drug layer, and drug release controlled membrane layer and manufactured by fluidized bed coater. The granule size and mombrane thickness can be controlled by various amounts of seed and coating solution, respectively. It could be observed that the morphology of osmotic granule was different at each coating step as well as type of coating solution. The bigger the size of granule, the slower the release rate was observed due to decreasing the total specific surface wed of granule. Also, it was observed that the increase of membrane thickness was caused to retard the dissolution of nifedipine due to decreasing the water absorption rate. The drug solubility for dissolution media is greatly affected to nifedipine release. From these results, we assured that osmotic granule can be fabricated by fluidized bed coating methods, and the appropriate release profile could be controlled by the controlling of bead size, membrane thickness and dissolution media.

• Korean Journal of Environmental Agriculture
• /
• v.18 no.1
• /
• pp.54-60
• /
• 1999

Three different types of lab-scale anaerobic bioreactors, AF and two-stage ASBF-PR and ASBF-SP, were evaluated in treating swine wastewater by operating at $1{\sim}2$ days of hydraulic retention time with increasing organic loading rate upto 6.3 $kg-COD/m^3{\cdot}d$ at $35^{\circ}C$. Seeding the anaerobic bioreactors with waste anaerobic digester sludge from a municipal wastewater treatment plant was effective and a 40-day acclimation period was required for steady-state operation. Three anaerobic bioreactors were effective in treating swine wastewater with COD removal efficiency of $66.4{\sim}84.9$% and biogas production rate of $0.333{\sim}0.796m^3/kg-COD_{removed}{\cdot}d$. Increases of organic loading rate by increasing influent COD concentration and/or decreasing hydraulic retention time caused decreases in COD removal efficiency and increases in biogas production rate. At relatively high organic loading rate employed in this study, the treatment efficiency of AF and ASBF-PR were similar but superior than that of ASBF-SP, indicating that porosity and pore size of the media packed in the bioreactors are more important factors contributing the performance of to bioreactors than specific surface area of the media. TKN in swine wastewater must be removed prior to the anaerobic processes when anaerobic process is considered as a major treatment process since influent TKN concentration of $1,540{\sim}1,870mg/L$ to the bioreactors adversely affect the activity of methanogenic bacteria, resulting in decreases of treatment efficiency and biogas production rate by 50%.

• Korean Journal of Environmental Agriculture
• /
• v.30 no.1
• /
• pp.9-15
• /
• 2011

BACKGROUND: This study was conducted to evaluate the effects of the fertilizer sources and ground cover mulches on nutrient release, growth, and photosynthesis in small one-year-old apple (Malus ${\times}$ domestica Borkh.) trees in controlled conditions. METHODS AND RESULTS: Treatments included no fertilizer (NF), commercial organic fertilizer (CF), and poultry litter (PL) for fertilizer treatments, and wood chips (WC), shredded paper (SP), green compost (GC), and grass clippings (GR) for cover mulch treatments. All treatments were applied proportionally based on the volume ratio equivalent to the soil. CF, PL, and GR treatments that had optimum carbon (C) and nitrogen (N) ratios (less than 30:1) for N mineralization through the microbes released the greatest $NH_4^+$ concentrations in the pot media at 90 days after the treatments, but GC mulch with the optimum C:N ratio did not. CF-, PL- and GR-treated plants had the largest leaf area, thickest stem diameter, longest shoot extension, and greater dry matter production. CONCLUSION(s): CF and PL showed an suitable organic nutrient source for improving plant growth in an orchard. Interestingly, GR also could be a nutrient source for tree growth, if vegetation competition is controlled by maintaining vegetation height and recycling enough grass clippings to the soil in an orchard.

• Korean Journal of Agricultural Science
• /
• v.4 no.2
• /
• pp.173-177
• /
• 1977

These experiments were conducted to investigate the formation of organic acid and ethanol during fermentation by three yeast strains. One of these was industrial strain (No.7) from Japan, and the others were wild types (No. 47, No. 239) isolated from Takju-mash and Strawbery, respectively. Conditions of fermentation were varied by differing the supply of oxygen (air), and by using different fermentation media The results obtained were as follows: 1) All the yeast strains produced higher amount of total organic acid and ethanol under the conditions which were aerobic, i.e. the flasks were opened during fermentation, than in case of using the flasks with fermentation bung. 2) Organic acid and ethanol were produced rapidly in the mash medium than in the semi-synthetic medium, i.e. total amount of organic acid and ethanol was maximized in a short time in the mash medium. 3) On the mash medium, the highest amount of organic acid was obtained by the strain No. 239, the next by No. 7 and the lowest by No. 47. Ethanol was produced on this medium with decreacing order of No. 47, No. 239, and No. 7. 4) The strain No. 239 was proved to be a powerful organic acid producer, yielding higher amount of organic acid especially under the aerobic conditions. 5) Above results suggests that the strain No. 239 could be of useful in alcoholic drink industry, due to its powerful ethanol-producing characteristic accompaning with high yielding of organic acids.

• KSBB Journal
• /
• v.15 no.3
• /
• pp.285-292
• /
• 2000

Support media for yeast immobilization was prepared from a porous volcanic rock used as a moisturizer in orchid growing. The rock was broken to the size of 2-3 mm and burned at $600^{\circ}C$ in a furnace in order to remove organic materials blocking the pores or treated with HCI solution or NaOH solution to remove the inorganic dirts by dissolving. Even through both the acid and the akali solution were effective the latter was not recommendable because it broke the pore structure by dissolving the elements of the media. This media was mainly consisted of SiO2 with $Al_2O_3$ as a minor component and CaO and K2O as trace elements. It had the finely developed pores of $15-80\mu\textrm{m}$size. Yeast immobilization capacity of this media was about $5{\times108}$ cells/ml bed which is large enough to be used for the practical applications. Yeast immobilization capacities of Alumina and Cordierite were much smaller than that of silica-based media. Scanning electron micrograph of Cordierite and Alumina showed uneven surfaces and small size of pores in contrast to relatively smooth surface and large pores of silica based media which means that smooth surface and large pores are desirable for the good adsorption of microbes on the media.

• KSBB Journal
• /
• v.17 no.3
• /
• pp.235-240
• /
• 2002

The surface of polypropylene was modified by 1 keV $Ar^+$ ion beam in an $O_2$ environment in order to enhance wettability. Contact angle of deionized water on modified polypropylene was reduced from $78^{\circ}$to $22^{\circ}$. The enhanced wettability is originated from newly formed functional groups such as ether, carbonyl, and carbonyl groups. During immersion in deionized water, the enhanced wettability has remained nearly same. After washing in water, the hydrophilic functional groups on the polymer surface have been very stable. The modified polypropylene was adopted as bio-film media to remove organics in synthetic wastewater. Microbe adhesion on the polypropylene surface was improved due to the newly formed hydrophilic groups.

• Journal of Korean Society on Water Environment
• /
• v.21 no.6
• /
• pp.669-675
• /
• 2005

Biological nitrate removal from groundwater was investigated in the biofilters packed with both gravel/sand and plastic media. Removal of particles and turbidity were also investigated in the 2-stage biofilter system consisted of biofilter and subsequent sand filter. In the single biofilter packed with gravel and sand, nitrate removal efficiency was dropped with the increase of filtration velocity and furthermore, nitrite concentration increased up to 3.2 mg-N/L at 60 m/day. Denitrification rate at the bottom layer below 25 cm was faster 8 times than upper layer in the up-flow biofilter. Nitrite build-up, due to the deficiency of organic electron donors, occurred at the upper layer of bed. Besides DO concentration and organic carbon, contact time in media was the main factor for nitrate removal in a biofilter. The most of the effluent particles from biofilter was in the range from 0.5 to $2.0{\mu}m$, which resulted in high turbidity of 1.8 NTU. However, sand filter followed by biofilter efficiently performed the removal of particles and turbidity, which could reduce the turbidity of final filtrate below 0.5 NTU. Influent nitrate was removed completely in the 2-stage biofilter and no nitrite was detected.

• Asian-Australasian Journal of Animal Sciences
• /
• v.13 no.7
• /
• pp.1010-1016
• /
• 2000

Effect on the bio-mass and nutrient yield of Lemna perpusilla Torry was studied at two nutrient loading frequencies. Six polythene sinks ($6{\times}2{\times}0.5m^{3}$ area) randomly allocated to two treatments having three sinks in each treatment. Each sink containing $6{\times}2{\times}0.35m^{3}$ water body, was changed either daily with 12.6 kg anaerobically fermented cattle manure (effluent) or with 76 kg efluent at six-day interval. Media Kjeldhal-N (40 vs. 36 mg/L; p>0.05) and $NH_3$-N (9 vs 7 mg/L; p<0.05) concentration were higher in daily charged sinks than those charged at six-day interval. However, temperature ($28.48{^{\circ}C}\;vs.\;28.60{^{\circ}C}$) and pH (6.82 vs. 6.84) were sinilar in both groups of sinks. Biomass (93 vs. $80g/m^{2}/d$) and crude protein (1.24 vs. $1.11g/m^{2}/d$) yield were non-significantly (p>0.05) higher in the daily charged than 6-d interval charged ponds. However, dry matter (4.52 vs. 4.15%), organic matter (83 vs. 84%), crude protein (31.4 va. 29.6%) and organic carbon (47 vs. 47%) content were similar in both daily and 6-d interval charged ponds. There were no apparent relationships between the crude protein content of Lemna and the media Kjeldhal-N or $NH_3$-N concentration apparently due to saturated level of nutrient (N in particular). It was concluded that with the level of effluent used for two treatments, nutrient-loading frequency had no significant effect on the biomass and protein yield of Lemna. Technique described here can be used for year-round duckweed production from fermented cattle manure for feeding poultry/fish in smallholder production system.