• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.106-114
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• 1998

In this research, single-, two- and four-stage intermittently aerated activated sludge system were investigated for simultaneous removal of nitrogen and phosphorus with swine wastewater. For the comparison of removal efficiency, conventional activated sludge system was operated. Operational conditions of intermittently aerated activated sludge system were SRT 20day, HRT 24hr and aeration/nonaeration time 1hr/1hr, respectively. Nitrogen and phosphorus removal efficiency in Intermittently aerated activated sludge system was upgraded compare with conventional activated sludge system. In single-stage intermittently aerated activated sludge system, release-uptake of $PO_4^{3-}-P$ was observed very well but, phosphosrus removal in effluent was not effective. In single-stage intermittently aerated activated sludge system, release-uptake of $PO_4^{3-}-P$ in first reactor, was observed very well but, in following reactor, $PO_4^{3-}-P$ concentation showed almost no change. T-N removal efficiency in conventional activated sludge system, single-, two-, and four-stage intermittently aerated activated sludge system were 48, 87, 90.9 and 95.5%, respectively, and phosphorus removal efficiency were 48, 75, 97 and 95%, respectively. Intermittently aerated activated sludge system as a alternative processes of conventional system leads to meet satisfactory effleunt with only on/off aeration regulation and save energy for aeration.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.99-106
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• 2001

A laboratory experiment was performed to investigate phosphorus and nitrogen removal from synthetic wastewater by intermittently activated sludge process packed with aluminium plate. Three continuous experimental systems, I. e. an intermittently activated sludge process(Run A), an intermittently activated sludge process with an aluminium plate packed into the reactor(Run B), and a reactor post stage(Run C) were compared. In the batch experiments, the phosphorus removal time in the reactor packed with copper and aluminium plate simultaneously was faster than that of the reactor packed with only an aluminium plates. However, the reactor packed with only an aluminium plate could be used for phosphorus removal. Move phosphorus was removed with an increase of surface area of aluminium plate and electrolysis(NaCl) concentration. The efficiency of COD and nitrogen removal was not affected in Run B. However, the phosphrus removal efficiency decreased because of reaction products and activated sludge which gradually covered gradually the surface of the aluminium plate. The efficiency of phosphorus removal in Run C was 86.3% at the HRT of 3.2 hours. Especially, the efficiency of phosphorus removal in Run C was higher than that in Run B.

• Journal of Environmental Health Sciences
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• v.28 no.3
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• pp.55-63
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• 2002

This study was carried out to treat textile wastewater using anaerobic sludge and aerobic fixed-bed biofilm reactor immobilized with Bacillus sp. dominated activated sludge(Bacillus sp. fraction : 81.5%). The range of influent con-centration of SCOD and soluble color were 1032-1507 mg/1, and 1239-1854 degree, respectively. Continuous treatment experiments were performed with variation of textile wastewater ratio at a same HRT. When textile wastewater ratio was 100%(HRT : 24 hours), The removal efficiency of SCOD and soluble color were 88% and 78%, respectively. When compare aerobic reactor of this study that was immobilized with Bacillus sp. dominated activated sludge to other study that was immobilized with activated sludge, SCOD and soluble color removal efficiency of this study showed a little higher efficiency than immobilized with activated sludge. The Bacillus sp. fraction of initial condition was 81.5%), but the fraction after operation was decreased to 31.8%).

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.234-238
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• 2008

Coarse pore filter could be an alternative of membrane for solid-liquid separation in an activated sludge reactor because of inexpensive cost of the filter material and high flux at low filtration pressure. However such filter module has much less specific filtration area compared to the membrane. Therefore a certain effort is required to increase the specific filtration area in the module design of such coarse pore filter for solid-liquid separation in an activated sludge reactor. In this study, tubular type coarse pore filter was designed at various diameter and configuration. The filtration performance was investigated to separate solid in the activated sludge reactor for domestic wastewater treatment. Tubular type coarse pore filter module could be successfully applicable to solid separation in the activated sludge reactor. The design parameters were the tube diameter of 10mm and vertical installation. Smaller diameter of the tube caused faster increase of the filtration pressure because of the hydraulic head loss in the tube channel.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.2
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• pp.104-116
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• 1996

Anaerobic digestion is generally used for the treatment of volatile organic solids such as manure and sludge from waste water treatment plants. However, the reaction rate of anaerobic process is slow, and thus it requires a large reactor volume. To minimize such a disadvantage, physical and chemical pre-treatment is generally considered. Another method to reduce the reactor size is to adopt different reactor system other than CSTR. In this paper, the effects of heat pre-treatment and reactor configurations on the anaerobic treatability of volatile solids was studied. Carrot, kale, primary sludge, and waste activated sludge was chosen as the test materials, and the BMP method was used to evaluate the maximum methane production and first order rate constants from each sample. After the heat treatment at $130^{\circ}C$ for 30min., the measured increase in SCOD per gram VS was up to 394 mg/L for the waste activated sludge. However, the methane production potential per gram VS was increased for only primary and waste activated sludge by 17-23%, remaining the same for carrot and kale. The overall methane production process for the tested solids can be described by first order reactions. The increased in reaction constant after heat pre-treatment was also more significant for the primary and waste activated sludge than that for carrot and kale. therefore, the heat pre-treatment appeared to be effective for the solids with high protein contents rather than for the solids with high carbohydrate contents. Among the four reactor systems studied, CSTR, PFR, CSTR followed by PFR, and PFR with recycle, CSTR followed by PFR appeared to be the best choice considering methane conversion rate and the operational stability.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.329-336
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• 2013

This study was conducted to reduce excess sludge generation by recycling of return sludge to the aeration tank after solubilization by electric field charger and ultrasonifier. The return sludge was purposely broken-up to the ratio of $SCOD_{Cr}/TCOD_{Cr}$ at 0.1, 0.2, and 0.3, which was tested along with control (i.e., untreated). Solubilized sludge was subsequently treated in a bench-scaled conventional activated sludge reactor. According to varying $SCOD_{Cr}/TCOD_{Cr}$ ratios, TSS in the reactor was correspondingly increased from 129 to 219 mg/L and $TCOD_{Cr}$ was also from 257 to 335 mg/L. However, TSS in the effluent was nevertheless kept lower at below 30 mg/L and $TCOD_{Cr}$ was also unvaryingly below 40 mg/L. For $SCOD_{Cr}/TCOD_{Cr}$ = 0.3, the amount of excess sludge produced was at the highest decreased up to as high as 78%.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.44-52
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• 1994

The purpose of this experimental research was focused to improve the quality of the effluent and the yielded sludge when the papermill wastewater was treated by the indirect aerated submerged biofilter as a second treatment method of papermill wastewater. Changing the various experimental factors(Nutrient additions or not, HRT, F/M ratio, recirculation ratio, etc) with indirect aerated biofilter, the results obtained are as follows. 1. Because of the microbes concentration could be sustained to $9,000mg/l$ in submerged biofilter and then the volumetric organic loads could be increased to $2.7kg-BOD/m^3/day$(that of activated sludge is $0.8kg-BOD/m^3/day$), the reactor volume can be reduced to one third of the activated sludge treatment. 2. Because of the yield coefficient(Y) and the endogenous decay coefficient(kd) were revealed 0.4 and 0.07/d, the yielded sludge volume was reduced by for compared with that of the activated sludgg process. 3. The concentration of the sloughed sludge in the reactor was 2.62~4.01%, so the thickener could be omitted in the papermill wastewater sludge treatment process. 4. When the operating was conducted at HRT of 4hrs, the treatment efficiencies of BOD and COD were obtained 80% and 70%, Therefore operating time can be reduced to one half of the activated sludge treatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.4
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• pp.91-97
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• 2008

The objective of this research is to investigate the effect of the addition of granular activated carbon (GAC) and granular sludge on the performance of upflow anaerobic sludge blanket (UASB) reactors for treating leachate. For the control reactor, sludge obtained from an anaerobic digester was used as a seed material. On the other hand, GAC and granular sludge were incorporated with the seed sludge in the GAC reactor and the Granule reactor, respectively. The shortest acclimation period was observed in the Granule reactor. The GAC reactor also gave comparable performance to the Granule reactor at the beginning of operation. However, as the adsorptive capacity of GAC was exhausted, the effluent COD concentration increased gradually. Once the systems were stabilized, the GAC reactor showed slightly better results than the other two reactors in terms of chemical oxygen demand (COD) removal. COD removal in all reactors was more than 90% at hydraulic retention time of 1.0 day. Furthermore, GAC reactor showed little variation in COD removal rate and remained at 95% with organic loading rate (OLR) of 4.0 to $8.2kg\;COD/m^3.d$. Initial operating period was reduced by the addition of granular sludge, while the treatment efficiency was enhanced by the addition of GAC.

• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.483-490
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• 2014

The design procedures for a biological reactor and a secondary settling tank (SST) of an activated sludge system are based on the steady state design method (Ekama et al., 1986; WRC, 1984) and the 1-D flux theory design method (Ekama et al., 1997), respectively. This study combined both of the design procedures, to determine the optimum sludge concentration in the reactor and the best design with the lowest cost. The best design of the reactor volume and the SST diameter at the optimum sludge concentration were specified with varying wastewater and sludge characteristics, temperature, sludge retention time (SRT) and peak flow rate. The effects of the influent wastewater characteristics, such as substrate concentration and unbiodegradable particulate fraction, were found to be considerable, but the effect of unbiodegradable soluble fraction was to be negligible. The effects of sludge settling characteristics, were also significant. SRT, as an operating parameter, was found to be an important factor for determining the optimum sludge concentration. However, the effect of temperature was found to be small. Furthermore, for designing a large scale wastewater treatment plant, the number of reactors or SSTs could be estimated, by dividing the total reactor volume or SST area. The new combined design procedure, proposed in this research, will be able to allow engineers to provide the best design of an activated sludge system with the lowest cost.