• KSBB Journal
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• v.6 no.2
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• pp.115-121
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• 1991

A number of experiments were conducted in order to investigate the COD removal rate according to the biofilm thickness in a Fluidized-Bed Biofilm Reactor(FBBR). The following conditions were fixed during the experiments: superficial upflow velocity was 0.47cm/sec, operating temperature was $22{\pm}1{\circ}C$ and pH was about $7{\pm}0.1$. The synthetic wastewater based on glucose was used as a substrate. The COD removal efficiencies were shown as 73% and 95%, respectively, when organic loading rate was increased from $10kgCOD\;/\;{\textrm{m}^3}$.day to $80kgCOD\;/\;{\textrm{m}^3}$.day. Andrew's model of substrate removal rate which was commonly used in fixed-biofilm reactor was transformed and applied in this FBBR experiment to predict substrate removal rate and gave 85% agreement with the experimental values.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.583-588
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• 2004

This research examined the treatment efficiency and methane production rate in treating slurry-type swine waste using UASB (upflow anaerobic sludge blanket) reactor. The UASB reactor was operated at an organics volumetric loading rate (VLR) of $2.6-15.7kgCOD/m^3/day$. A stepwise increase of the VLR resulted in a temporary deterioration in the COD removal rate in UASB reactor but recovered quickly. The COD removal rate were 65-70% for VLR up to $5 kgCOD/m^3/day$. When organics VLR was $10kgCOD/m^3/day$, the COD removal rate decreased sharply and there was loss of 17.537g of the seeding biomass due to sludge washout. This result indicated that the UASB system cannot be adapted to more than $10kgCOD/m^3/day$ of VLR. As the organic load increased from 2.6 to $15.7kgCOD/m^3/d$, the biogas production rate varied from 3.2 to 10.8 L/d and the methane conversion rate of the organic matter varied from 0.30 to $0.23m^3CH_4/kg\;COD_{removed}$. The methane content showed the range of 70.1-81.5% during the experimental period. The volatile solids (VS) removal efficiency was similar at the low VLR (< $5 kgCOD/m^3/day$), but it decreased sharply at the high VLR (> $5 kgCOD/m^3/day$). The VS reduction rate was, moreover, large those of COD. The result shows that hydraulic retention time above 2 days is essential in case of treating wastewater containing 1% of solids.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.617-622
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• 2011

Ozone-based advanced oxidation was applied for the treatment of anaerobic digestion effluent of livestock wastewater. Initial COD and color value were 930 mg/L and 0.04, respectively, and the 1/10-diluted wastewater was used for the study. The treatment characteristics were compared between the conventionally generated ozone ($105{\mu}m$) and microbubbled ozone ($13{\mu}m$). The use of microbubbled ozone improved the removal of chemical oxygen demand (COD) and color by 85% and 26%, respectively, compared with the conventionally bubbled ozone. The application of microbubbled $O_3/UV$, $O_3/H_2O_2$, $O_3/UV/H_2O_2$ combinations resulted in 5~10% higher color removal than ozone alone, which implies that the contribution of UV or $H_2O_2$ is not significant in color removal. On the other hand, COD removal could be increased two folds compared with ozone alone through $O_3/UV/H_2O_2$ combination. The contribution of $H_2O_2$ was bigger than UV for COD removal with microbubbled ozone. Due to the enhancement of dissolved ozone and radical activity, the microbubbling enabled us to additional COD removal even after stopping ozone supply in the presence of UV or $H_2O_2$.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.279-284
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• 2013

In this study, the feasibility of a single-stage thermophilic aerobic process for the treatment of high-strength food wastewater produced from the recycling process of food wastes was examined to substitute anaerobic digestion process. Also, the removal and stability of thermophilic aerobic process were assessed according to the changes of hydraulic retention times (HRTs) and organic loading rates (OLRs). When the OLR increased from 9.2 to $37.2kgCOD/m^3d$, a pH value in R1 (HRT : 5 d) significantly decreased to 5.0, due to the organic acid accumulation. On the other hand, the pH value in R2 (HRT : 10 d) was stable and R2 showed the high removal of COD, organic acid and lipid, even though the OLR increased from 4.6 to $18.6kgCOD/m^3d$. In R1, the COD loading rates for COD removal was suddenly dropped, as the COD loading rate increased from 18.6 to $28.4kgCOD/m^3d$. In contrast, R2 showed that the COD loading rates for COD removal increased with regard to increment in the loading rates of 3.61, 7.05, 9.43 and $12.2kgCOD/m^3d$, indicative of the high COD removal efficiency. Therefore, the results demonstrated that over 10-d HRT, the high concentration of raw food wastewater was efficiently treated in the single-stage thermophilic aerobic process.

• Journal of Industrial Technology
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• v.16
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• pp.61-70
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• 1996

This research aims to find granulation and organic removal of the piggery wastewater with the upflow blanket filter(UBF) reactor. UASB process had the effect of high pH on the granulation phase. But teh effect was decreased after the granule formation. The filter zone of the UBF reactor had the function of GSS and contributed to removing the organic because of its biofilm formation. The removal rates of total COD and soluble COD were 70% ~ 80% and 60 ~ 80% at an influent organic loading range of $2{\sim}17.4kgCOD/m^3{\cdot}d$, respectively. The methane production rate with the organic removal was $0.21{\sim}0.34{\ell}CH_4/gCOD_{rem}$ and the maximum methan production rate was $0.34CH_4{\ell}/gCOD_{rem}$ at the volumetric loading $5kgCOD/m^3{\cdot}d$.

• Clean Technology
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• v.7 no.2
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• pp.89-97
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• 2001

The purpose of this study was to find the optimum condition of the high removal efficiency of water pollutant as sewage treatment technology using a filtering bed charged with porous sintering-pellet which was planted with hydrophytes. Experiment was carried out by changing concentration of water pollutants(COD, T-N, T-P), kind of hydrophyte, kinds of filtering material and size, and HRT. The result of removal efficiency was obtained as following: COD removal 73.8~87.1% for input concentration range of 50~450mg/L, T-N removal 61.3~77.3% for input concentration range of 7~124mg/L, T-P removal 89.5~99.1% for input concentration ranger of 3~27mg/L. In a comparative experiment of three kinds of hydrophyte(Iris pseudoacorus, Phragmites communis $T_{RIN}$., Oenanthe javanica Dc.), the best removal efficiency of COD and T-N was gained with Iris pse-udoacorus, and Phragmites communis $T_{RIN}$ showed better result than two hydrophytes for the removal efficiency of T-P. In a comparative experiment of four kinds of filtering-materials, the removal efficiencies were in the order of porous sintering-pellet, gravel, nonused-tire and nonused-concrete. It was found that for the porous sintering-pellet, the smaller its diameter, the better its result. In the filtering bed in which was charged with porous sintering-pellets of 5mm diameter and planted with Iris pseudoacorus, the removal efficiency of COD, T-N and T-P were over 80%, 70% and 90% under the concentration of COD 250mg/L, T-N 70mg/L and T-P 15mg/L for 24hrs treatment. Thus, we concluded that a filtering bed charged with porous sintering-pellet and planted with hydrophytes will be suitable for treatment of sewage water as a pro-natural treatment technology.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.71-77
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• 2015

A fluidized biofilter was filled with Pseudomonas sp. and Bacillus cereus/thuringiensis-fixed waste-tire crumb media and was run to treat authentic textile-dyeing wastewater mixed with alkaline polyester-weight-reducing wastewater. As a result, its removal efficiency of $COD_{Cr}$ and color were 75~80% and 67%, respectively. In addition, upon constructing hybrid-recirculating system composed of the fluidized biofilter and a 450 W-UV/photocatalytic reactor, only fluidized biofilter was run bypassing UV/photocatalytic reactor at stage I. Subsequently, the hybrid system was continuously run at stage II-i, ii and iii. At stage II-i, the total removal efficiency of $COD_{Cr}$ was enhanced to be 80~85%, compared to 75% at stage I, owing to 20~30% removal efficiency of the UV/photocatalytic reactor. However, at stage II-i, the total removal efficiency of color was enhanced to be 65~70%, compared to 45~65% at stage I, even though the removal efficiency of the UV/photocatalytic reactor was tantamount to merely 0~5%. As far as the removal efficiency of fluidized biofilter of the hybrid-recirculating system is concerned, its removal efficiency of color was enhanced by the synergy effect of the hybrid-recirculating system unlike $COD_{Cr}$. Besides, despite of the increase of hybrid-recirculating system-recycle ratio, the deactivation of photo-catalytic activity was scarcely observed to eliminate the color while its irreversible deactivation was observed to eliminate $COD_{Cr}$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.77-88
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• 1988

This research investigated the effect of COD/N ratio on nitrogen removal, and the use of organics in raw wastewater as a carbon source for denitrification in SBR(Sequencing Batch Reactor) systems. Four laboratory scale reactors were operated in three modes. Only the difference between modes were; Mode I operated in aerated condition during fill while Mode II in anoxic condition and Mode III operated on two fills per cycle in anoxic condition. When COD/N ratio increased, total nitrogen removal efficiencies increased from 8.7 to 57.7 percent in Mode I, from 28.9 to 83.2 percent in Mode II and from 42.7 to 97.8 percent in Mode III, respectively. COD removal efficiencies ranged from 93 to 98 percent throughout the study. SBR operation in Mode III of feeding twice per cycle in anoxic condition was an effective operating method for nitrogen removal and nitrogen concentration in effluent can be estimated using influent COD and nitrogen concentrations.

• KSBB Journal
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• v.24 no.4
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• pp.353-360
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• 2009

This study was accomplished using Anaerobic/Anoxic/Oxic upflow packed-bed column reactors with fixed media and Loop Reactor with fluidized media instead of Oxic reactor. The objectives of this study was to investigate the characteristics of organics, nitrogen and phosphorus removal from sewage with the HRT. The average removal efficiencies of $BOD_5$ and SS increase as increasing the hydraulic retention time (HRT) until 16 h of the HRT, and they were constant over 16 h of the HRT. The removal efficiency of $BOD_5$ in case of packed-bed reactor and Loop Reactor was about 86.6% and 90.9% respectively at 16 h of the HRT. The removal efficiency of SS in packed-bed reactor and Loop Reactor was about 78.0% and 88.2% respectively at 16 h of the HRT. The average removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ showed similar trends as those of $BOD_5$ and SS. At the HRT of 16 h, the removal efficiency of $COD_{Cr}$ in case of packed-bed reactor and Loop Reactor was 63.5%, 75.2% and that of $COD_{Mn}$ was 60.7%, 73.6% respectively. The average removal efficiencies of T-N and T-P increase as increasing the HRT. The removal efficiencies of T-N and T-P in Loop Reactor were 33.6% and 54.5% respectively at 16 h of the HRT and T-N and T-P were better removed in Loop Reactor. From this result, it was found that the performance of Loop Reactor was much higher than the performance of packed-bed reactor and the optimum HRT was 16 h.

• Membrane and Water Treatment
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• v.11 no.3
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• pp.217-222
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• 2020

An electrochemical oxidation process was applied to remove cyanide (CN^-) from real plating wastewater. CN^- removal efficiencies were investigated under various operating factors: current density and electrolyte concentration. Electrolyte concentration positively affected the removal of both CN^- and Chemical Oxygen Demand (COD). As the electrolyte concentration increased from 302 to 2,077 mg Cl^-/L, removal efficiency of CN^- and COD increased from 49.07% to 98.30% and from 23.53% to 49.50%, respectively, at 10 mA/㎠. Current density affected the removal efficiency in a different way. As current density increased at a fixed electrolyte concentration, CN^- removal efficiency increased while COD removal efficiency decreased, this is probably due to lowered current efficiency caused by water electrolysis.