• Journal of Korean Society of Water and Wastewater
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• v.19 no.2
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• pp.125-134
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• 2005

Waste concrete powder was used to remove fluoride ions in highly concentrated fluoride wastewater. 92.6% of fluoride in 100 mg F/L wastewater was removed by 1% dose of the cement paste powder that represents characteristics of waste concrete powder, whereas the removal efficiencies of raw cement and lime were 47.3% and 96.4%, respectively. The cement paste powder was competitive to lime, common fluoride removal agent. Various Ca-bearing hydrates such as portlandite, calcium silicate hydrate, and ettringite in cement paste slurry can remove fluoride by precipitating $CaF_2$ and absorbing $F^-$ ions. In the experiments using both cement paste and lime, 50~67% of lime can be substituted by cement paste to satisfy fluoride effluent limitation of 15 mg/L. Since cement paste has higher acid neutralization capacity than lime, it can be recycled to neutralize more acid and to remove more fluoride. Therefore waste concrete powder can be more economical and viable alternative for lime in fluoride wastewater treatment.

• Environmental Engineering Research
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• v.13 no.4
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• pp.203-209
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• 2008

This paper presents the experimental results in five months operation from a combined anaerobic/oxic system treating swine waste with average concentrations in organic matter and nitrogen of 7,930 mgCOD/L and 671 mgTKN/L, respectively. The system was formed using an upflow anaerobic sludge blanket (UASB) reactor and oxic reactor connected in series with a recycling line of oxic effluents to UASB for its denitrification. The UASB reactor was operated at an organic volumetric loading rate (VLR) of $2.1{\sim}4.5\;kgTCOD/m^3$/day and the removal efficiency of TCOD was $66.3{\sim}85.4%$. The overall removal efficiency of TCOD was more than 99%. The oxic reactor was operated at a nitrogen VLR of $0.10{\sim}0.20\;kgTKN/m^3$/day and the nitrification efficiency was 75%. However, the complete denitrification was observed in the UASB reactor that was due to the optimal temperature and sufficient carbon source. The overall removal rate of TN was about 80%. About 76.2% of the influent COD mass was accountable in a COD mass balance at a level of VLR $3.64\;kgCOD/m^3$/day. The production rate of methane was $0.32\;LCH_4/gCOD_{removed}$ when influent organics, VLR, were recorded by $3.4{\sim}4.5\;kgCOD/m^3$/day.

• Journal of Environmental Health Sciences
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• v.14 no.1
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• pp.63-71
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• 1988

This study is an experimental research on the anaerobic digestion of pig manure and night soil mixed waste at room temperature (25$\circ$C), and the results are shown below: 1. The steady-state condition based on gas production as digestion temperature dropped to 25$\circ$C from 35$\circ$C was achieved at around 28, 47, 56, 64 days respectively when its hydraulic retention time(HRT) are 10, 20, 30, 40 days. 2, Alkalinity and volatile acid(VA) was increased as increasing the organic loading. 3. Removal efficiency of chemical oxygen demand(COD) and biochemical oxygen demand (BOD) was improved as longer HRT, and generally COD value is lower and BOD value is higher relatively. 4. Overall treatment efficiencies of mixed waste are higher than of pig manure and of night soft. 5. Organic removal efficiency at room temperature (25$\circ$C) is 20-25% lower at medium temperature (35$\circ$C) in a same VS loading condition. 6. Refractory fraction of the infiuent VS and organic removal rate constant(K) estimated at around 37% and 0.107/day respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.498-504
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• 2004

Removal of waste generated by Paralichthys olivaceus in the seawater aquarium using a foam separator was investigated. Protein concentration without a foam separator continuously increased until 3 days after stocking and reached at 25 mg/L after 5 days stocking, but protein concentration became lower than the initial protein concentration (2.5 mg/L) with a foam separator. The trends of other fish wastes such as ammonia, total suspended solids (TSS) and chemical oxygen demand (COD) were similar to protein. Dissolved oxygen (DO) in the aquarium decreased below 6.0 mg/L without a foam separator, but with a foam separator the average DO in the aquarium was 7.3 mg/L. Foam separation with the increase of superficial air velocity (SAV) was more effective than that with the fixed SAV. This study showed that wastewater. treatment of seawater aquarium using a foam separator is effective method for a fish waste removal and oxygen supply.

• Resources Recycling
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• v.21 no.2
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• pp.9-16
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• 2012

This review evaluates a number of different agricultural waste adsorbents and types of dyes. Certain wastewater containing different dye contaminants causes serious environmental problems. Recently, growing research interest in the production of carbon based has been focused on agricultural by-products. Low cost adsorbents derived from agricultural wastes have demonstrated outstanding capabilities for the removal of dyes from waste water. The use of cheap and eco-friendly adsorbents have been studied as an alternative substitution of activated carbon for the removal dyes from wastewater.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.92-97
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• 2024

The LiBr aqueous solution, which is the absorption liquid of absorption refrigerator, must be replaced periodically because the concentration of impurities such as Cu²⁺, Fe²⁺, Ca²⁺, etc., increases due to corrosion of the tubes as the period of use increases, and the refrigeration efficiency decreases significantly. In order to reuse the waste absorption liquid, flocculation-precipitation method is mainly applied to precipitate the impurities, which requires hundreds of times the concentration of impurities and generates additional waste. In this study, a process for removing Cu ion impurities from cyclone electrolyzer by electrolytic reduction is presented in a small-scale facility without additional waste. It was confirmed that Cu ion impurities can be removed down to 1 ppm by electrolytic reduction process, and to further improve the removal rate, the mass transfer rate was increased by using a cyclone electrolyzer. The removal rate of Cu ions increased with the increase of flow rate and current density, and it was confirmed that Cu was removed at a rate of 1.48 ppm/h under the condition of 330 mL/sec and 2.5 mA/cm².

• Journal of Soil and Groundwater Environment
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• v.29 no.2
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• pp.1-10
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• 2024

With industrial development, the inevitable increase in both organic and inorganic waste necessitates the exploration of waste treatment and utilization methods. This study focuses on co-pyrolyzing lignin and red mud to generate metalbiochar, aiming to demonstrate their potential as effective adsorbents for water pollutant removal. Thermogravimetric analysis revealed mass loss of lignin below 660℃, with additional mass loss occurring (>660℃) due to the phase change of metals (i.e., Fe) in red mud. Characterization of the metal-biochar indicated porous structure embedded with zero-valent iron/magnetite and specific functional groups. The adsorption experiments with 2,4-dichlorophenol and Cd(II) revealed the removal efficiency of the two pollutants reached its maximum at the initial pH of 2.8. These findings suggest that copyrolysis of lignin and red mud can transform waste into valuable materials, serving as effective adsorbents for diverse water pollutants.

• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.371-377
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• 2002

The purpose of this study is to develop effective operating process in order to achieve more suitable conditions of Anoxic-Oxic-Anoxic-Stripper(AOAS) SBR through real-time control. To improve the removal efficiency, glucose, methanol and synthetic food waste acid fermentant were added as an external carbon source, In the case of glucose and synthetic food waste acid fermentant, TN, TP were removed to average 86.9%, 73.0% respectively. Methanol was removed to average 64.6%, 55.4% respectively. The synthetic food waste acid fermentant proved to be the most efficient and allowed for the substitution of an external carbon source. The removal rate of $COD_{Cr}$, was approximately 90% at all cases. The results of the study that a correlation between ORP (Oxidation-Reduction Potential), pH and DO and nitrification or denitrification when an external carbon source is added and when it isn't was showed that ${\Delta}ORP$ is suitable parameter. ORP reacted properly to denitrification (${\Delta}ORP<-10$) and nitrification (${\Delta}ORP<0$). The use of real-time control saved anywhere between 61 and 67 minutes at the anoxic(1) stage and 26 to 52 minutes at the oxic(1) stage. When the time saved from the anoxic(1) and oxic(1) was added to the anoxic(2) stage for the removal efficiency of TN and TP increased from 0.7 to 13.9% and 12 to 35 % respectively.

• Clean Technology
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• v.8 no.3
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• pp.167-172
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• 2002

The adaptability of earthworm casts produced form the waste sludge of pulp and paper plants for a biocarrier used in the advanced wastewater treatment was investigated. Removal efficiencies of nutrients in the activated sludge technology without carrier were compared with those treated with carrier made of casts under the different conditions such as the composition of the input and kinds of carrier. When the waste water was treated in the activated sludge technology without carriers, removal efficiencies of T-P and T-N were average values of 31% and 52%, respectively. On the contrary, pellet type carrier and pack type carrier increased the removal efficiencies of T-P and T-N by 1.3~1.4 and 1.9~2.0 times, respectively. At the same time, the high removal of T-P and T-N were observed irrespective of the types of carrier in which many kinds of microorganisms were grown. The difference in the removal efficiencies of BOD and COD between the treatment with and without carrier was negligible. According to this research, the carrier made of casts was thought to be highly applicable in the advanced wastewater treatment.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.48-53
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• 1999

In this study, various batch tests were performed to examine the utilization of waste oyster shells for removal of $PO_4^{3-}-P$ in livestock wastewater, because waste oyster shells have been known to be very porous and to have alkaline minerals such as calcium and mangnesium. $PO_4^{3-}-P$ removal rate were increased by waste oyster shells, as specific surface area and contact efficiency per unit area of their were increased. Generally, it could be showed that $PO_4^{3-}-P$ removal rate were very influenced by particle size, dosage and temperature. At low pH of initial reactions, it would be showed that $PO_4^{3-}-P$ removals were directly influenced by adsorption but crystallization process were dominated with passed time and pH increasing. The SEM observed that the variations were hardly seen, but particle sizes of waste oyster shell were relatively big after reactions and showed forms of smaller plate than before reactions.