• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.219-225
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• 2008

Evaluating and designing secondary clarifier require to define characteristics of influent MLSS (Mixed Liquor Suspended Solids). In this study, bioflocculation and settling characteristics for MLSS from a Biological Nutrient Removal (BNR) plant located in near Seoul were measured. MLSS concentrations in bioreactor were about 2,500mg/L in summer and about 4,000mg/L in winter, respectively. Tests showed that there was not much bioflocculation occurred in secondary clarifier. Average ESS/DSS (Effluent Suspended Solids/Dispersed Suspended Solids) was 100%. From the settling tests, ZSV (Zone Settling Velocity) and settling constant (n) in Vesilind equation were estimated at different MLSS temperatures. SVI (Sludge Volume Index) and SSVI (Stirred Sludge Volume Index) were also measured at different temperatures. It was found that ZSV was positively correlated with temperature and n was inversely proportional to temperature. SVI and SSVI had very similar values at about $25^{\circ}C$ of MLSS, However, SVI had more than 2 times higher values than SSVI at below $20^{\circ}C$ of MLSS. Temperature effect must be considered to design and evaluate secondary clarifier.

• Journal of Environmental Health Sciences
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• v.27 no.1
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• pp.112-118
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• 2001

The aim of this study was to evaluate on the removal effect of total nitrogen and phosphorus in municipal wastewater with temperature change from 1$0^{\circ}C$ to 24$^{\circ}C$ in CNR(Cilia Nutrient Removal) process. CNR process is the process combining $A^2$/O process with cilium media of H2L company. The removal efficiencies for T-N were found to be 57.9% at 1$0^{\circ}C$ below, 53.7% at 10-2$0^{\circ}C$, 52.2%at 20-24$^{\circ}C$ and 44.4% over 24$^{\circ}C$ respectively. The removal efficiencies for T-P were 53.3% at 1$0^{\circ}C$ below, 59.1% at 10-2$0^{\circ}C$, 72.4% at 20-24$^{\circ}C$ and 50.0% over 24$^{\circ}C$ respectively. The specific nitrification rate (kg NH$_3$-N/kg MLSS.d) of Oxic basin was 0.088 and 0.053 at 1$0^{\circ}C$ below, 0.077 at 10-2$0^{\circ}C$, 0.097 at 20-24$^{\circ}C$ and 0.088 over 24$^{\circ}C$ respectively. The specific denitrification rate (kg NH$_3$-N/kg MLSS.d) in anaerobic and anoxic was 0.013, 0.008 respectively.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.9
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• pp.469-475
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• 2016

The study is the result of an practical operation analysis for the full scale fishery product wastewater treatment plant with immersed MBR (iMBR) process. Since fishery product industries show a wide range of wastewater generation by the season, design and operation of the equalization basin are very important factor. The aeration system for the equalization basin mixing can save the chemical consumption for followed system through the restriction of acid fermentation. The concentrations of wastewater primary DAF process treated were BOD 2,291 mg/L, $COD_{Mn}$ 530 mg/L, SS 256.8 mg/L, T-N 38 mg/L, T-P 13.5 mg/L respectively. It was considered that iMBR is the most efficient biological process for high salinity content wastewater since It is irrelevant to the capability of the sludge precipitation. SADp and SADm were 0.31, $26.5m^3/hr{\cdot}m^3$ respectively. In iMBR process, the critical F/M ratio was derived at 0.08~0.10 gBOD/gMLSS by analysing the correlations between MLSS, normalized TMP and temperature. The effluent concentrations were BOD 1.8 mg/L, $COD_{Mn}$ 12.4 mg/L, SS 1.0 mg/L, T-N 7.85 mg/L, T-P 0.1 mg/L and removal efficiencies were 99.9%, 97.6%, 96.3%, 95.7%, 97.8% respectively.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.1-9
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• 2013

Long term hydrogen production was investigated in an anaerobic sequencing batch reactor (ASBR) using mixed microflora. Glucose (about 8,250 mg/L) was used as a substrate for the ASBR operation under the condition of pH 5.5 and $37^{\circ}C$ with mixing at 150 rpm. The experiment was carried out over a period of 160 days. Hydrogen yield was 0.8mol $H_2/mol$ glucose with F/M ratio 2 at initial operation period. The hydrogen yield reached to maximum 2.6 mol $H_2/mol$ glucose at 80th day operation. However decreased hydrogen yield was observed after 80 days operation and eventually no hydrogen yield. Although well-known hydrogen producer Clostridium sp. was detected in the reactor by PCR-DGGE analysis, changed reactor operation was the major reason of the decreased hydrogen production, such as low F/M ratio of 0.5 and high propionic acid concentration 2,130 mg/L. Consequently the long period operation resulted in MLSS accumulation and then low F/M ration stimulating propionic acid formation which consumes hydrogen produced in the reactor.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.112-118
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• 2009

Ammonia-oxidizing bacteria (AOB) are chemolithoautotrophs that play a key role in nitrogen removal from advanced wastewater treatment processes. Various AOB species inhabit and their community compositions vary over time in the wastewater treatment bioreactors. In this study, a hypothesis that operational and environmental conditions affect both the community compositions and the diversity of AOB in the bioreactors was proposed. To verify the hypothesis, the clone libraries based on ammonia monooxygenase subunit A were constructed using activated sludge samples from aerobic bioreactors at the Pohang, the Palo Alto, the Nine Springs, and the Marshall wastewater treatment plants (WWTPs). In those bioreactors, AOB within the Nitrosomonas europaea, N. oligotropha, N.-like, and Nitrosospira lineages were commonly found, while AOB within the N. communis, N. marina, and N. cryotolerans lineages were rarely detected in the samples. The AOB community structures were different in the bioreactors: AOB within the N. oligotropha lineage were the major microorganisms in the Pohang, the Palo Alto, and the Marshall WWTPs, while AOB within the N. europaea lineage were dominant in the Nine Springs WWTP. The correlations between the AOB community compositions of the wastewater treatment bioreactors and their operational (HRT, SRT, and MLSS) and environmental conditions (temperature, pH, COD, $NH_3$, and $NO_3{^-}$) were evaluated using a multivariate statistical analysis called the Redundancy Analysis (RDA). As a result, COD and $NO_3{^-}$ concentrations in the bioreactors were the statistically significant variables influencing the AOB community structures in the wastewater treatment bioreactors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.21-29
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• 1985

An effective technique of sludge separation is required for concentrated activated sludge process. The dissolved-air flotation (DAF) has been shown to be efficient process for sludge separation. The factors affecting DAF process for activated sludge separation are type and concentration of sludge, air/solid ratio, ratio of pressurized water flow, pressure, sludge detention time, temperature, sludge and hydraulic loading rate, recycle flow rate of sludge and type and quantity of chemical aid. In order to study the optimal operation condition for sludge separation, the influence factors such as type and concentration of sludge, ratio of pressurized water flow and pressure are investigated by the batch and continuous reactor experiments of DAF and sedimentation test. By the experimental investigation, the results are as follows; 1. For the bulking and concentrated sludge, DAF is more effective than sedimentation for the sludge separation. 2. In DAF, the critical ratio of pressurized water flow exist. The critical value varies with the pressure in the tank. That is, according to the pressure changes from 3 to $5kg/cm^2$, the critical value varies from 0.25 to 0.67 accordingly. 3. Pressure affects the ratio of pressurized water flow, but it does not show any influence upon the DAF efficiency directly. 4. Continuous experimental results was not better than those of batch.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.137-145
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• 1990

In this research, biological uptake of heavy metals(Cd(II), Cu(II), Zn(II)) was measured under various conditions ; pH, initial heavy metal concentration, temperature, contact time and the amount of biomass through batch test. From this research, it was found that heavy metals might be removed through adsorption and accumulation in activated sludge process. Heavy metals were highly concentrated by microbial floc in activated sludge. Also, the removal efficiency was reached up to 80~90% within and after 1 hour the increase of removal efficiency was minimal. The order of accumulation efficiency was Cu(II)>Zn(II)>Cd(II), and the bonding strength between heavy metals and microbial floc may be expressed in order of Cu(II)>Zn(II)>Cd(II).

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.639-647
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• 2006

The temperature effect at $20^{\circ}$ and $10^{\circ}$ on the nutrient removal efficiency was evaluated in the combined biological nutrient removal system (CBNR) with anaerobic-intermittent aerobic-oxic reactors. The test was conducted under the conditions of various ratios of intermittent aeration time and distribution of influent raw water to CBNR. The removal efficiencies of organics, nitrogen and phosphorus were a little bit better at $20^{\circ}$ than at $10^{\circ}$. However the large difference of temperature effect on the nutrient removal efficiency between $20^{\circ}$ and $10^{\circ}$ was not appeared because of highly sustained MLSS concentrations in the reactors and controlled intermittent aeration time. In the removal of phosphorus, Mode III (50/70 min in aeration on/off time, 3 times of intermittent aeration) showed more effective compared with short aeration time of Mode IV. In case of N, P removal, the denitrification rate was lower in Mode A with splitted inflow into anaerobic and intermittent aeration basins than in Mode B with sole inflow into anaerobic basin.

• Journal of Environmental Health Sciences
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• v.22 no.2
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• pp.90-95
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• 1996

This study was performed to calculate the degration rate coefficient, operating parameters to meet the effluent standards, and the temperature adjustment coefficients to each parameter of pollution by seasonal variation of concentration and temperature of influent in livestock wastewater treatment by sequencing batch reactor process in field scale. The followings are the conclusions that were derived from this study. 1. In the field, temperature of livestock wastewater in reactor was 20.3$\circ$C in summer and 6.0$\circ$C in winter. The ratio of BOD:TKN: T-P in influent was 100:80:7. BOD loadings in winter and spring were 0.26 and 0.43 kg $BOD/m^3$ day, respectively. Those in summer and fall were 0.25 and 0.13 kg $BOD/m^3$ day, respectively. 2. The degradation rate coefficient for TKN was larger in summer and fall in which temperature was high than that in which temperature was high than that in winter and spring in which concentration was high. On the contrary, the phosphorus uptake rate was larger in winter and spring than that in summer and fall. 3. The hydraulic retention time in winter and spring was longer than that in summer and fall. Especially, in order to meet the standard for TKN of 120 mg/l in winter in which temperature of wastewater was 6.0$\circ$C, as the MLSS concentration was increased from 4, 000 to 7, 000 mg/l, the hydraulic retention time was increased from 212 to 121 hours. But, in order to shorten that less than 121 hours for the economical wastewater treatment, countermeasure to increase temperature of wastewater in the reactor should be considered. 4. the temperature adjustment coefficients for BOD, $COD_{Mn}$, TKN and T-P were 1.0241, 1.0225, 1.0541 and 1.0495, respectively. Namely, the treatment of TKN was most sensitively affected by temperature. For the purpose of the effective removal of nitrogen and phosphorus which are sensitive to temperature, it is necessary to keep the temperature of livestock wastewater more than 20$\circ$C which is the temperature of it in summer.

• 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.