• Journal of Korean Society of Water and Wastewater
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• v.9 no.2
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• pp.84-96
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• 1995

The dewatering characteristics of the sewage sludge was investigated through the experimental observations and model simulations. The activated sludge and the anaerobically digested sludge were examined for the dewaterability evaluation within the pressure range of $0{\sim}10^6N/m^2$. Modified Buchner funnel test and compression test by the consolidometer were conducted to evaluate average specific resistance, porosity, and moisture percentage of filter cake. Shirato's technique of compression-permeability test was followed for the pressure range lower than about $10^2N/m^2$. The flocculation effects on sludge dewatering was also examined for ferric chloride and polymeric flocculant. The application of hydrated lime which can be used for flue-gas desulfurization showed improved moisture percentage, and was thought to have positive feasibility in combined system of sludge dewatering and incineration. Determined characteristic constants were applied to Tiller's cake filtration model to simulate liquid pressure distribution and porosity distribution in cake. Model simulations showed a sharp drop of the porosity close to the cake-medium interface for the highly compressible material such as the activated sludge and the anaerobically digested sludge.

• 한국생물공학회:학술대회논문집
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• 2004.07a
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• pp.21-33
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• 2004

In this study, Anaerobic sewage sludge in a batch reactor operating at $35^{\circ}C$ was used as the seed to investigate the effect of pretreatments of waste activated sludge and to evaluate its hydrogen production potential by anaerobic fermentation. Various pretreatments including physical, chemical and biological means were conducted to utilize for substrate. As a result, SCODcr of alkali and mechanical treatment was 15 and 12 times enhanced, compared with a supernatant of activated sludge. And SCODcr was 2 time increase after re-treatment with biological hydrolysis. Those were shown that sequential hybridized treatment of sludge by chemical & biological methods is most efficient process for sludge treatment. The pre-treatment activated sludge was tested to conform hydrogen production potential in batch experiments. When buffer solution was added to the activated sludge, hydrogen production potential increased as compare with no addition.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1090-1097
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• 2006

The anoxic activated sludge process was applied to the treatment of industrial box-mill wastewater, which exhibited the high removal efficiencies of $90{\sim}94%$$ TCOD_{Mn}$ and $58{\sim}81%$ Color. For the design of industrial anoxic activated sludge process, Monod bio-kinetic coefficients of box-mill wastewater were estimated as follows: $K_{max}$(maximum specific substrate removal rate)=0.52 $day^{-1}$, $K_s$(half saturation constant)=314 mg/L, $K_d$(decay coefficient)=0.274 $day^{-1}$, y(microbial yield coefficient)=0.908 mg/mg, and ${\mu}_{max}$(maximum specific growth rate)=0.472 $day^{-1}$. Space loading factors for the design analysis were practically determined as the values of F/M ratio=$0.043{\sim}0.07$ kg-$TCOD_{Mn}$/kg-SS-day, BOD space loading=$0.18{\sim}0.3$ kg-$TCOD_{Mn}/m^3-day$, and ${\theta}_x=6.8{\sim}26.4$ day when considering the relationship of these loading factors with growth dynamics of microorganisms, the F/M ratio that is inversely proportional to ${\theta}_x$ should be equivalent to ${\mu}_{max}$ in units, but exhibited the significant difference between theses two values. Therefore, it is considered that high safety factors are requested in the design of anoxic activated sludge process that is based on Monod bio-kinetics of microorganism.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.172-179
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• 1999

In this research, biological treatability test was conduced using seawater flocculated tannery wastewater by fixed biofilm reactor. During one cycle, the removal efficiency of organic corbon obtained with fixed biofilm process for treating tannery wastewater was considerably greater than that with activated sludge process. As the hydraulic retention time increased form 0.5day to 4day, removal efficiency of organic carbon was increased from 72% to 87.3%. Attached biomass in media increased with influent organic loading up to 29g MLSS/L, that could reduce the specific organic loading rate. The continual measurement of attached biomass was possible for the operation of the biofilm reactor. Equal and low nitrication rates were observed in both suspended growth activated sludge process and fixed biofilm process, despite commercial nitrifier was seeded. Through the process of treating the tannery wastewater, EC50 values which is measured by the use of Ceriopdaphnia dubia, were decreased to the extent of 50% after treatment of seawater flocculation and of 83% after biological treatment, respectively, compared to those of the untreated wastewater.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.33-42
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• 2018

Microscopic examination of the activated sludge and morphological characterization of the flocs provides detailed information about the treatment process. The aim of this study is to investigate the morphological parameters of flocs obtained from a thermophilic jet loop membrane bioreactor (JLMBR) in different sludge retention times (SRTs), considering EPS and SMP concentration, hydrophobicity, zeta potential. The results showed that irregularity decreased with the increasing SRT. The compactness value was calculated to be less than 1 for all SRTs. However, the sludge had a more compact structure when the SRT increased. Zeta potential increased whereas hydrophobicity and floc size reduced, with increasing SRT. Furthermore, 2-D porosity calculated using the hole ratio was higher at greater SRTs. Hence, there was a significant correlation between the results obtained using the imaging technique and operation conditions of thermophilic JLMBR.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.875-883
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• 2006

The carbon and nitrogen removal process using PVA-gel (Polyvinyl Alcohol) immobilized microorganisms was studied. The process has been operated under diverse process conditions for 12 months. The process consists of denitrification with internal recycle of 300%, nitrification, aerobic digestion reactors and settling tank. Nitrificatoin and nitrogen removal efficiency according to gel packing ratio and temperature were studied. Yield for Heterotrophs ($Y_H$), decay coefficient for Heterotrophs($b_H$) in aerobic digestion reactor were determined to seize sludge reduction mechanism and compared with typical data of activated sludge process. Then SRT in aerobic digestion reactor was determined on an experimental basis and sludge reduction efficiency was calculated. The process was implemented successfully with sludge reduction efficiency of 92.0~98.5% on a basis of biomass.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.69-75
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• 1988

Two rational formulae depicting the relationships between sludge ages and recycle flow rates have been developed to determine sludge wasting volumes at a particular sludge age. A sensitivity analysis shows that the recycle ratio is the most important variable to be measured as accurately as possible in determining the sludge wasting volume to maintain a particular sludge age when the system is controlled by wasting recycled sludge. On the other hand, the final clarifier solids capturing capacity is the most important variable to be measured when the system is operated by wasting mixed liquor.

• Journal of Environmental Science International
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• v.27 no.4
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• pp.233-240
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• 2018

The purpose of this study was to confirm the applicability of aerobic granular sludge (AGS) in the advanced sewage treatment process. Simulated influent was used in the operation of a laboratory scale reactor. The operation time of one cycle was 4 h and the reactor was operated for six cycles per day. The volume exchange ratio was 50%. The influent was injected in divisions of 25% to increase the removal efficiency of nitrogen in every cycle. As a result, the removal efficiencies of $COD_{Cr}$ and TN in this reactor were 98.2% and 76.7% respectively. During the operation period, the AGS/MLVSS concentration ratio increased from 70.0% to 86.7%, and the average $SVI_{30}$ was 67 mL/g. The SNR and SDNR were 0.073-0.161 kg $NH_4{^+}$-N/kg MLVSS/day and 0.071-0.196 kg $NO_3{^-}$-N/kg MLVSS/day respectively. These values were higher or similar to those reported in other studies. The operation time of the process using AGS is shorter than that of the conventional activated sludge process. Hence, this process can replace the activated sludge process.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.480-485
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• 2004

Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Nocardia amarae causing a nuisance foaming problem in activated sludge process. The identified signature peak was 19:1 alcohol as a reliable unique peak to N. amarae. Chemostat study revealed that the distribution and quantity of fatty acid peaks were dependent on the growth stage of Nocardia. The FAME results were similar for two relatively high dilution rates; however, the amounts of signature peaks extracted from the 4 and 6 day cultures were significantly higher. This dependence of signature peaks on the physiological state of the organism may be a useful information to assess the health of microbial populations in activated sludge. A laboratory scale batch foaming potential experiment provided a critical foaming level depending on Nocardia population. This critical Nocardia level determined in this study was in terms of either the threshold filament intersections number or the threshold signature FAME amount. The threshold peak area of signature FAME (19:1 alcohol) and corresponding filament counts were 430PA/mg VSS and $1.45{\times}10^6$ intersections/g VSS, respectively. The threshold signature FAME level could be effectively applied as a criterion for diagnosing foam occurrence in activated sludge system.

• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1717-1723
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• 2010

The integrated fixed-film activated sludge (IFAS) system is a variation of the activated sludge wastewater treatment process, in which hybrid suspended and attached biomass is used to treat wastewater. Although the function and performance of the IFAS system are well studied, little is known about its microbial community structure. In this study, the composition and diversity of the bacterial community of suspended and attached biomass samples were investigated in a full-scale IFAS system using a high-throughput pyrosequencing technology. Distinct bacterial community compositions were examined for each sample and appeared to be important for its features different from conventional activated sludge processes. The abundant bacterial groups were Betaproteobacteria (59.3%), Gammaproteobacteria (8.1%), Bacteroidetes (5.2%), Alphaproteobacteria (3.9%), and Actinobacteria (3.2%) in the suspended sample, whereas Actinobacteria (14.6%), Firmicutes (13.6%), Bacteroidetes (11.6%), Betaproteobacteria (9.9%), Gammaproteobacteria (9.25%), and Alphaproteobacteria (7.4%) were major bacterial groups in the attached sample. Regarding the diversity, totals of 3,034 and 1,451 operational taxonomic units were identified at the 3% cutoff for the suspended and attached samples, respectively. Rank abundance and community analyses demonstrated that most of the diversity was originated from rare species in the samples. Taken together, the information obtained in this study will be a base for further studies relating to the microbial community structure and function of the IFAS system.