• Journal of Environmental Health Sciences
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• v.18 no.2
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• pp.57-61
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• 1992

This study was made for enhanced removal of N and P by intermittented aeration Activated Sludge Process. Experiment were conducted to find the effects of aeration interval and nutrient removal efficiency. When applied aeration interval were 30~60 min, 2~4 h, 4~8 h, organic matter was not affected while phosphorous removal was aeration interval 30~60 min. Also, when applied mixing intensity were 15, 30, 45 and 60 rpm, organic matter was not affected while removal was maximum at 15 rpm. Total nitrogen and phosphorous removal were in the range of 76 and 85%. Density and MLSS of Sludge were in the range of 2.3~2.6 and 7198~7810 mg/l. Release of phosphorous from activated sludge under unaerobic condition was increased as pass time.

• Environmental Engineering Research
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• v.11 no.3
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• pp.143-148
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• 2006

The ultrasonics is a new technology in waste activated sludge(WAS) treatment. Ultrasonic treatment is well known method for the break up of microbial cells to extract out a variety of intercellular materials inside microorganism cell. This study was done to investigate the effects of the ultrasonic frequency and power on disruption of biosolids in WAS and to examine the effect on methane production of WAS treated by ultrasonics. Biosolids disruption with ultrasound is more effective at ultrasonic frequency of 40 kHz and power of 0.3 watt/mL. In the digestion with WAS pretreated by sonication time for 10 minute at 40 kHz and 0.3 watt/mL, the total quantity of generated methane increased by 75%, as compared with experimental control(non-treatment).

• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.561-570
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• 2013

There are two types of rectangular secondary clarifier at biological nutrient removal (BNR) facility to settle MLSS; conventional activated sludge secondary clarifier and Gould Type I clarifier. In this study, the performances of two types at respective biological nutrient removal facility are compared using weekly operational data. Surface Overflow Rate (SOR), Surface Loading Rate (SLR), Sludge Volume Index (SVI), secondary effluent SS concentration are studied. It has found that Gould Type I has 3.5 times less average secondary effluent SS concentration that is 2.4 mg/L than that of conventional activated sludge secondary clarifier. Both SOR and SLR have shown little effect on secondary effluent SS concentrations at Gould Type I clarifier in contrary that SOR affects the secondary effluent SS concentrations at conventional activated sludge rectangular secondary clarifier. From this study, it is recommended that Gould Type I must be considered for secondary clarifier when BNR plant is designed.

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.32-36
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• 2021

Milking parlor wastewater contains not only high concentrations of organic compounds, but often animal antibiotics. To discharge the antibiotics to public water area cause problem of antibiotics resistant bacteria. Magnetic separation was applied into improvement of milking parlor wastewater treatment process. A new process, composed of a magnetic activated sludge (MAS) process and a contact oxidation (CO) process, was proposed in this study. This process was evaluated by the simulated milking parlor wastewater (4500 mg/L COD_Cr and 10 mg/L tetracycline) using a bench scale experimental setup. As a result, the process was able to removed 97% COD_Cr as well as 94% tetracycline. The MLVSS (mixed liquor volatile suspended solids) concentration of MAS was maintained at 12000 mg/L without excess sludge drawing. This process was considered to be useful as treatment process for milking parlor wastewater in which waste-milk including antibiotics is often discharged.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.343-348
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• 2010

The objective of this study was to investigate the effects of starvation periods with aerobic or non-aerobic conditions on the organic removal efficiencies and physical characteristics of activated sludge for treating saline and non-saline wastewater. During the experiment, MLSS, MLVSS, sludge volume index (SVI), floc size and fractal dimension, $COD_{Mn}$ removal efficiencies were monitored. The reductions of MLSS, MLVSS and SVI with maintaining the sludge under a non-aerobic condition during starvation periods were smaller than those under a aerobic condition. Floc size, fractal dimension and $COD_{Mn}$ removal efficiencies were less decreased under non-aerobic condition than under aerobic condition. And SVI were strongly correlated with floc size and fractal dimension. Consequently, the result showed that maintaining the activated sludge under non-aerobic starvation conditions was better strategy than that under aerobic starvation conditions as it adapted and resisted to starvation.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.304-310
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• 2007

The purpose of this research was to investigate the effects of the co-treatment of municipal wastewater with microwave-irradiated excess sludge on the treatment efficiency and excess sludge production of the activated sludge process. When 250 mL of excess sludge with a MLSS concentration of approximately 2,000 mg/L was microwave-irradiated at $20^{\circ}C$ for $40\sim300$ sec by a microwave oven (2,450 MHz, 700 W), the temperature of the sludge increased at a rate of approximately $20^{\circ}C/min$ and the SCOD, TKN and T-P concentrations of the sludge showed the highest increase in the irradiation time of $40\sim130$ sec. And, the oxygen uptake rate measurement of the sludge microorganism suggested most of the microorganisms in the sludge were destroyed at an irradiation time above 130 sec(above $65^{\circ}C$). When the municipal wastewater and microwave-irradiated excess sludge was co-treated by the activated sludge process, almost no effect was observed in the pH and alkalinity of both the influent and effluent, but the influent concentrations of SS, COD, T-N and T-P increased. Even though the effluent SS, BOD and T-P concentrations showed almost no effect, the COD and TKN concentrations increased. The microbial yield coefficient decreased at a rate of 0.91 g SS/g COD removed as the irradiation ratio increased at a rate of 1 g SS/g SS-day.

• Clean Technology
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• v.15 no.1
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• pp.31-37
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• 2009

This study deals with the production process of activated carbons from the sewage sludge char by chemical activation reaction. KOH and NaOH were used as activating agents, which react well with carbon. From the experiments, it was found that activated carbons made with KOH treatment had better physicochemical properties in terms of iodine number and BET value than those made with NaOH treatment. It was also found that the optimal deposition ratio of an activating agent to the sewage sludge char was 75 wt% of KOH and 50 wt% of NaOH. Activated carbons were washed out by distilled water after neutralization with 5 M hydrochloric acid solution. The activated carbons that were produced from a sewage sludge char at this optimal conditions have BET surface areas of approximately $600m^2/g$.

• Journal of Microbiology and Biotechnology
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• v.22 no.7
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• pp.1005-1014
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• 2012

The understanding of the relationship between ammonia-oxidizing bacteria (AOB) communities in activated sludge and the operational treatment parameters supports the control of the treatment of ammonia-rich wastewater. The modifications of treatment parameters by alteration of the number and length of aerobic and anaerobic stages in the sequencing batch reactor (SBR) working cycle may influence the efficiency of ammonium oxidation and induce changes in the AOB community. Therefore, in the research, the impact of an SBR cycle mode with alternating aeration/mixing conditions (7 h/1 h vs. 4 h/5.5 h) and volumetric exchange rate (n) on AOB abundance and diversity in activated sludge during the treatment of anaerobic sludge digester supernatant at limited oxygen concentration in the aeration stage (0.7 mg $O_2/l$) was assessed. AOB diversity expressed by the Shannon-Wiener index (H') was determined by the cycle mode. At aeration/mixing stage lengths of 7 h/1 h, H' averaged $2.48{\pm}0.17$, while at 4 h/5.5 h it was $2.35{\pm}0.16$. At the given mode, AOB diversity decreased with increasing n. The cycle mode did not affect AOB abundance; however, a higher AOB abundance in activated sludge was promoted by decreasing the volumetric exchange rate. The sequences clustering with Nitrosospira sp. NpAV revealed the uniqueness of the AOB community and the simultaneously lower ability of adaptation of Nitrosospira sp. to the operational parameters applied in comparison with Nitrosomonas sp.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.2
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• pp.93-100
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• 2010

In this study, ways to help anaerobic digestion were studied and waste activated sludge were pretreated by grinding, thawing after freezing and grinding after freezing. The volumes of grinding sludge, thawing after freezing and grinding after freezing were decreased 2.08 times, 3.37 times, 3.54 times compared to the volume of sludge respectively and the larger decline in the sludge has been grinding after freezing, thawing after freezing, and grinding. In addition, when the concentrations of SCOD, SBOD and protein were compared, the concentration of freezing sludge was higher than others and the grinding after freezing method seems to be the highest concentration. When the TS, VS removal rates were compared, thawing after freezing method seems to be higher than others method. From these results, grinding after freezing method is very effective for the pretreatment of sludge and it can be expected grinding after freezing method can be an alternative method for prohibiting ocean dumping of sludge after 2012.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.277-284
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• 2021

The ballasted flocculation effects of the mill scale and magnetite on activated sludge were investigated. Both ballasted flocculants (BF) could remarkably improve the sludge settleability in terms of zone settling velocity (ZSV) and sludge volume index (SVI). With the BF dosage of 0.2 to 2.0 g-BF/g-SS, the magnetite particles showed better efficiency on improving settling behavior of activated sludge than the mill scale due to higher surface area and hydrophobic property. The efficiency of SVI₃₀ with magnetite injection was 2.5 to 11.3% higher than mill scale injection and that of the ZSV appreciated from 23.7% to 44.4% for magnetite injection. Averaged floc size of the BF sludge with magnetite dosage (0.5 g-BF/g-SS) was 2.3 times higher than that of the control sludge. Dewaterability of the sludge was also greatly improved by addition of the BF. The specific resistance to filtration (SRF) was reduced exponentially with increasing the dosage of BF. However, the BF's particle size effect on the SRF looks to be marginal. Consequently, for improving the dewaterability, the BF played a physical role to remove the pore water of the biological flocs by intrusive attachment and a chemical role to induce aggregation of the flocs by charge neutralization.