• Journal of Korean Society of Water and Wastewater
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• v.8 no.3
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• pp.9-18
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• 1994

Activated sludge pilot plant testing was conducted to determine the ability of a well-designed activated sludge treatment system to remove chromic toxicity from the bleached kraft pulp mill effluent. Removals of conventional(BOD and SS) and nonconventional(resin and fatty acids, color, AOX) pollutants were estimated. The pilot plant was operated at steady state for about 10 weeks at an F/M of 0.28 and a sludge age of 8.4 days. The average MLSS concentration was 4,309mg/l, of which volatile fraction was 57%. During the operation period, the BOD removal reaction rate(k) was determined to be 8.2/day at $30^{\circ}C$. The BOD removal was 84 percent, which was 3 to 6 percent lower than expected for full-scale treatment. The chronic toxicity of the activated sludge effluent was tested by employing both Dinnel and the BML protocols. It was found that the pilot plant could achieve in excess of 90 percent reduction in chronic echinoderm toxicity. The data show slight reduction of color and AOX across the activated sludge system. The pilot system, however, demonstrated on excellent removal of resin and fatty acids.

• Journal of Environmental Health Sciences
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• v.19 no.3
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• pp.1-16
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• 1993

This paper describes an investigation to determine whether the activated sludge (AS) process could be used for the treatment of wastewater at the Union Carbide Coporation (UCC) plant in Seadrift, Texas. This plant presently utilizes a waste stabilization pond (WSP) system for treatment of the wastewater. The treatment system consists of an in-plant primary WSP and two off-plant WSPs (secondary and tertiary WSPs), run in series. The total hydraulic detention time of the WSP system is approximately 150 days. Several laboratory-based treatability studies have been conducted to evaluate the performace of the WSP system and the degradability of specific chemical compounds. From an additional study, it was determined that the WSP system was stressed and occasionally operating near the limit of its treatment capacity. The existing primary WSP plays an important role in the overall treatmemt system, because it not only functions as a pH and organic-strength equalization basin, but also serves as a "preconditioning" basin by fermenting high strength organic wastes to volatile organic acids for subsequent degradation in the escondary WSP. However, in view of pending RCRA legislatin conerning the "proposed organic toxicity characteristics limits" (40 CFR Part261: Federal Register, July, 1988), it is possible that the primary WSP will have to be abandoned in favor of alternative treatment options. Therefore the main purpose of this study was to perform activated sludge treatability evaluations for the development of an alternative to the existing primary WSP treatment ststem. In addition, another purpose was to determine the degradability of bis(2-chloroethyl)ether (Chlorex or CX) and benzene(BZ) in the activated sludge process. The presence of these two chemicals in the wastewater of the plant prompted the question of whatedether they could be degraded in an activated sludge system.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.289-296
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• 2001

The effects of HRT and effluent time on removals of pollutants in the electrochemical pilot were investigated. COD removal after 8 hour electrochemical reaction time in HRT 30 and 60 minutes were higher than that of 15 minute HRT. Turbidity removal was 90% or greater regardless of conditions during effluent time. Removals of T-N and T-P during effluent time in HRT 30 and 60 minutes were $71{\sim}74%$ and $85{\sim}98%$, respectively. To evaluate the combination of activated sludge process and continuous electrochemical as pretreatment, the removal efficiencies of pollutants was investigated. In two treatment processes of a single activated sludge system and a electrolysis pilot plus activated sludge systems, SVI and MLSS during effluent time were kept with $82{\sim}112$ and $1,230{\sim}1,750$ mg/L, respectively. COD removal was approximately 90% at early effluent time for both treatment systems, but COD removal in a single activated sludge was slightly decreased as effluent time went by, compared with the single activated sludge COD removal was slightly increased in the early stage of the electrolysis plus activated sludge system. Turbidity removal during effluent time was higher than 95% for both treatment systems. T-N removals during effluent time in a single activated sludge system and a electrolysis pilot plus activated sludge systems were $62{\sim}74%$ and $72{\sim}86%$, respectively. T-P removal in a electrolysis pilot plus activated sludge systems was increased by 9% at early effluent time and 15% after 72 hours of effluent time in compared with a single activated sludge system.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E2
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• pp.41-48
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• 2005

A novel hybrid system composed of a biotrickling filter and an activated sludge reactor was investigated under the conditions of four different SRTs (sludge retention times). The performance of the hybrid reactor was found to be directly comparable among the four different sludge ages. Discernible differences in the removal performance were observed among four different SRTs of 2, 4, 6, and 8 days. High removal efficiency was achieved by continuous circulation of activated sludge over the immobilized mixture culture, which allowed on pH control, addition of nutrients, and removal of paint VOCs (volatile organic compounds). The results also showed that the removal efficiency for a given pollutant depends on the activity of microorganisms based on the SRT. As the SRT increased gradually from 2 to 8 days, the average removal performance decreased. The highest removal rate was achieved at the SRT of 2 days at which the highest OUR (oxygen uptake rate), $6.1mg-O_2/liter-min$ was measured. Biological activity in the recycle microbes decreased to a much lower level, $3.6mg-O_2/liter-min$ at a SRT of 8 days. It is thus believed that young microorganisms were more active and more efficient for the VOCs removal of low concentrations and high flow rates. The apparent correlation of $R^2=0.996$ between the average removal efficiency and the average OUR at each SRTs suggests that VOCs degradation by young cells significantly affected the overall removal efficiency for the tested SRTs.

• KSBB Journal
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• v.11 no.5
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• pp.577-585
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• 1996

Effects of various factors on the phenol degradation by activated sludge immobilized with the photo-crosslinked resin were investigated. The optimum pH on the degradation of phenol in both free and immobilized activated sludge was 7. When the pH of the reaction was varied from 5 to 10, the relative activity of the phenol degradation by the immobilized activated sludge was higher than that by the free activated sludge. A higher rate of phenol degradation was observed when a bead size was smaller. The phenol degradation in the free activated sludge was inhibited at the 3000 mg/L of phenol, while that in the immobilized activated sludge was maintained at the same concentration for 28 hrs without an inhibition. The degradation rates of phenol were not directly proportional to the increasing amount of immobilized beads dosage, but the phenol degradation was made in a rather short time than that for a free sludge system. The relative activities of the immobilized activated sludge after 7 runs of repeated reactions increased about 8 times as that of the first reaction. The activities for the phenol degradation remained stable for at least 80 days when the immobilized activated sludge was stored at an aerobic condition in the wastewater containing phenol. The loading rate as high as 5.59 kg-pheno1/㎥.d could have been achieved during the continuous treatment of phenol by the immobilized activated sludge.

• 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.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.1 no.1
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• pp.56-61
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• 2001

Activated sludge processes are broadly used in the biological wastewater treatment processes. The activated sludge processes are complex systems because of the many factors such as the variation of influent flowrate and ingredients, the complexity of biological reactions, and the various operation conditions. The main motivation o this research is to develop an intelligent control strategy for activated sludge process (ASP). ASP is a complex and nonlinear dynamic system owing to the characteristic of wastewater, the change in influent flowrate, weather conditions, and so on. The mathematical model of ASP also includes the uncertainty which is a ignored or unconsidered factor from process designers. The ASP model based on Matlabⓡ/Simulinkⓡ is developed in this paper. And the model performance is examined by IWA (International Water Association) and COST (European Cooperation in the filed of Scientific and Technical Research) data. The model tests derive steady-state results of 14 days. In this paper, fuzzy logic control approach is applied to handle DO concentrations. The fuzzy logic controller includes two inputs and one output to adjust air flowrate. The objective function for the optimization, in the implemented evolutionary strategy, is formed with focusing on improving the effluent quality and reducing the operating cost.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1592-1596
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• 2010

To verify the dominance of microorganisms in wastewater biological treatment, PCR-DGGE (denaturing gradient gel electrophoresis) was performed as a supplementary support method for screening of the dominant microorganisms from activated sludge. Results suggest that the dominant microorganisms in activated sludge are primarily responsible for strengthening its effectiveness as a biological treatment system, followed by the non-main dominant microorganisms, whereas the non-dominant microorganisms showed no effects. The degree of microbial abundance present on the profile of PCR-DGGE was in line with the treatment efficiency of augmented activated sludge with isolated cultures, suggesting that PCR-DGGE can be used as an effective supplementary method for verifying culturable dominant microorganisms in activated sludge of coking wastewater.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.3
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• pp.151-155
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• 2004

The bioremediation of water system contaminated with phenolic compounds having endocrine-disrupting activity, i.e. 2,4-dichlorophenol, 2,4-dichlorophenoxy acetic acid (2,4-D), and 2,4,5-trichlorophenoxy acetic acid (2,4,5-T), was investigated by using ozone oxidation and activated sludge treatment. Ozone oxidation (ozonation time: 30 min) followed by activated sludge treatment (incubation time: 5 days) was an efficient treatment method for the conversion of phenolic compounds in water into carbon dioxide and decreased the value of total organic carbon (TOC) up to about 10% of initial value. Furthermore, 2,4-D was dissolved in water containing salt, i.e. artificial seawater (ASW), and this water was used as model coastal water contaminated with phenolic compounds. The activated sludge treatment (incubation time: 5 days) could consume significantly organic acids produced from 2,4-D in the model costal water by the ozone oxidation (ozonation time: 30min) and decrease the value of TOC up to about 35% of initial value.

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.57-65
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• 1998

In this research, Effect of C/N ratio on nutrient removal in intermittently aerated activated sludge system(IAASS) was investigated with dormitary, building and swine wastewater. Three types (2-stage, 4-stage, modified) of IAASS were operated. Time interval of aeration/nonaeration in IAASS was 1hr/1hr. In treatment of Dormitary wastewater(BOD/T-N ratio : 4.4), Building wastewater (BOD/T-N ratio : 3.14) and swine wastewater(BOD/T-N ratio : 3.84), Nitrogen removal efficiency of 80, 70 and 90.4% was achieved, respectively. Nitrogen removal in IAASS was a great influenced on influent C/N ratio, efficient nitrogen removal was achieved at BOD/T-N ratio over 4. In IAASS operation, $\Delta $BOD mg/L/$\Delta $ nitrogen mg/L ratio was about 4-6. Simultaneous removal of organic, nitrogen and phosphorus in IAASS can achieved. And influent organic was efficiently utilized in denitrification. IAASS could be one of the best alternative process for the retrofit of conventional activated sludge system for the removal of nutrients.