• 한국환경과학회지
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• 제15권10호
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• pp.945-949
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• 2006

For a membrane bio-reactor, it is possible to fillet and separate activated sludge and effluent by head loss of centimeters, if non-woven fabric material is used as titration media. However, if non-woven fabric material is used to thicken high-concentration sludge, excessive sludge attachment causes the rapid decrease of flux. Mesh with fore sizes of $100{\mu}m,\;150{\mu}m,\;and\;200{\mu}m$ allows for easy separation of attached sludge. This study examined the possibility of mesh as filtration media. Existing close-flow filtration process, which requires maintaining sludge movement, makes It difficult to obtain high thickening rate. With a view of complementing this weakness, this study has made an experimental examination on how high-concentration sludge (about 3,000mg/L to 10,000mg/L) will be filtered and thickened when mesh module is submersed in the bio-reactor. Effluent flowed from the bottom of the bio-reactor by head loss of 65cm. In case of pore size of $100{\mu}m$, SS showed high recovery of 80% to 96%; therefore, it has been decided that mesh can be used as filtration media. Filtration lasted for more than 9 hours, until sludge with 9,000mg/L in MLSS concentration was thickened 9 times as dense. In the range from 3,610mg/L to 9,060mg/L in MLSS concentration, it was possible to obtain effluent with less than 2mg/L in MLSS concentration within 10 minutes.

• 상하수도학회지
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• 제21권4호
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• pp.429-437
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• 2007

This study aims to develop a sulfur-using denitrification process which is possible a renovation to advanced treatment plant submerging a simple module in activated sludge aeration tank. At first, the impact factor of sulfur-using denitrification was appreciated by the batch test. Secondly, reflecting a dissolved oxygen effect of sulfur-using denitrification that was confirmed by the batch test, in a continuous nitrification/sulfur-using denitrification, high-rate nitrogen removal reaction was induced at optimum condition controlling DO concentration according to phases. Also, inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. Result of batch test for sulfur-using denitrification, $NO_2{^-}N$ was lower for consumption of alkalinity and sulfur than that of $NO_3{^-}-N$. These results revealed the accordance of theoretical prediction. In continuous nitrification/sulfur-using denitrification experiment, actual wastewater was used as a influent, and influent nitrogen loading rates were increased 0.04, 0.07, 0.11, $0.14kg\;N/m^3-day$ by changing hydraulic retention times. At this time, nitrogen loading rates of packed sulfur were increased 0.23, 0.46, 0.69, $0.93kg\;N/m^3-day$. As a result, nitrification efficiency was about 100% and denitrification efficiency was 93, 81, 79, 72%. Accordingly, nitrogen removal was a high-rate. Also the module of sulfur-using denitrification covered with microfilter did not make a fouling phenomena according to increased flux. And the module was achieved effluent suspended solids of below 10 mg/L without a clarifier. In conclusion, it is possible a renovation to advanced treatment plant submerging a simple module packed sulfur in activated sludge aeration tank of traditional facilities. And the plant used the module packed sulfur is expected as a effective facilities of high-rate and the smallest.

• 상하수도학회지
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• 제13권1호
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• pp.61-71
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• 1999

For a high-rate fermentation and recovery of organic acid, we have developed a new organic acid fermentation reactor with membrane filter, which is the most important part in the new advanced wastewater treatment system. The recovered organic acid is to be reused as an organic carbon source at denitrification process. Some experiments were conducted to compare the performance of acid fermentation at different SRTs, such as 5, 10, and 20 days. The total organic acid concentration produced during the runs was in the range of 2,100-2,900 (mgC/L). The conversion efficiency from substrate to organic acid reached to from 43% to 59%. The recovery rate of organic acid from substrate based on TOC was from 26% to 53%. Regardless of operational conditions, it has been able to maintain the membrane flux constantly, in the range of 0.4-0.46 ($m^3/m^2/day$). The transmembrane pressure drop was 0.2-0.3 (kg/cm) for 100 day's operation. The result of simulation is as follows. Organic removal efficiency of the new advanced treatment system is 95%. 73% of Nitrogen is removed. The removal efficiency of Phosphorus is 93%. By coqulation, soluble phosphorus is able to remove from the water treatment lines, which is impossible at conventional activated sludge system. The unit construction cost is 65000 (yen/m3) and it was 1.4 times than that of the standard activated sludge system. The unit operation cast is 7.7 ($yen/m^3/day$) and it was 1.3 times than that of the standard activated sludge system.

• 신재생에너지
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• 제1권2호
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• pp.60-72
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• 2005

The effect of alkaline pre-treatment on the solubilization of waste activated sludge(WAS) was investigated, and the biodegradability of WAS, pretreated WAS, [PWAS], food waste and two types of mixture were estimated by biochemical methane potential [BMP] test at $35^{\circ}C$. The biodegradability of PWAS and mixture waste were significantly improved due to the effect of alkaline hydrolysis of WAS. An alkaline pre-treatment was identified to be one of the useful pre-treatment for improving biodegradability of WAS and mixture waste. In high-rate anaerobic co-digestion system coordinate with an alkaline pre-treatment in process, the digesters were operated at the HRT of 5, 7, 10 and 13 days with a mixture of FW $50\%\;and\;PWAS\;50\%,\;$In term of $CH_4$ content, VS removal and specific methane production [SMP] which are the parameters in the performance of digester, the optimum operating condition was found to be a HRT of 7 days and a OLR of 4.20g/L-day with the highest SMP of 0.340 L $CH_4/g$ VS.

• 한국물환경학회지
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• 제20권3호
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• pp.197-205
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• 2004

Batch test methods have developed for a long time to measure kinetic and stoichiometric parameters which are required to perform steady state design and mathematical modelling of activated sludge processes. However, at various So/Xo ratios, abnormal behaviors of ordinary heterotrophic organism in batch tests have been reported in many researches. Thus, in this research, abnormal behaviors of heterotrophs in batch tests were investigated at various So/Xo conditions by measuring and interpreting oxygen utilization rate. As So/Xo ratio increased, the calculated values of maximum specific growth rates, ${\mu}_{H,max}$ and $K_{MP,max}$, increased. However, at a certain point of So/Xo (around 10mgCOD/mgMLAVSS), ${\mu}_{H,max}$ and $K_{MP,max}$ values started to decrease. According to this observation, three prominent behaviours of heterotrophs were identified at various So/Xo conditions. (1) At low So/Xo region (below 5 mgCOD/mgMLAVSS), the oxygen utilization rate of heterotrophs in batch tests were almost stable and consequently yielded lower maximum specific growth rate. (2) At high So/Xo region (up to 5~10 mgCOD/mgMLAVSS), oxygen utilization rate incresed sharply with time and indicated more upward curvature than the predicted OUR with conventional activated sludge model, which consists of single hetetrotrophs group. Thus, in this region, competition model of two organisms, fast-grower and slow-grower, seemed to be appropriate. (3) At extremely high So/Xo region (over 10mgCOD/mgMLAVSS), significant oxygen utilization rate was still observed even after depletion of readily biodegradable COD. This might be caused by retarded utilization of intermediates which were generated by self inhibition mechanism in the process of RBCOD uptake.

• 한국환경보건학회지
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• 제30권1호
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• pp.7-14
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• 2004

The change in filamentous bacteria appearance was observed by adjusting factors such as organic and nurient concentration of feed wastewater and the aeration rate in the reactor. In case that COD:N:P and DO were 100:10:1 and 6.1 m1/1 respectively, the mean SVI was 122 ml/g and the filaments were developed normally in flocs. For the low DO con- dition, however, the SVI averaged 186 ml/g and the appearance of outgrowing filaments were more frequent. When the high organic was supplied into the reactor, the average SVI was 274 ml/g and the distinct filamentous bulking was observed. Meanwhile when COD:N:P was maintained at 100: 1 :0.5, the SVI was as low as 87 ml/g and the appearance of filaments were minimal and the size of flocs was small comparing other experimental conditions. For normal, low aeration and high organic concentration, predominant filaments in the early stage of experiments were commonly Type 021N,S. natans which were usually found in low DO condition. However, Type 041, Type 1851, Type 0961 became predominant as experiments extended. Meanwhile, in low nutrient condition, Type 0675, Type 1851, and Type 0961 were observed. The filamentous bacteria appearance for SVI< 150(ml/g), Type 0041, Type 0961 (usually low organic in feed wastewater) were predominantly observed and SVI > 150(ml/g), S. natans and Type 021N(usually low DO in aeration basin) was predominant.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 Proceedings of KSEH.Minamata Forum
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• pp.51-53
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• 2005

Disposal of waterwork sludge is important problem in WTP(water treatment plant). Purpose of this study is treated municipal waste water chemically using sludge that is produced in waterwork plant by link to reutilize waterwork sludge. Municipal waste water that use in an experiment used is produced at C university, and is SS 220 mg/L, BOD 145 mg/L, COD 160 mg/L, T-N 52 mg/L and T-P 2.6 mg/L. Used Alum, polymer coagulant and coagulant aid (diatomite, powered activated carbon) as CaO, coagulant as alkaline aid by chemical treatment medicine. In case of does slow speed agitation and stations after pours waterwork sludge in sewage and alkaline aid and coagulant at rapidly mixing the colloidal creation speed is fast and fine colloids concentration was high but settling time is shortened a little and removal rate of pollutant improved by $60{\sim}99%$.

• 한국환경보건학회지
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• 제20권2호
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• pp.22-27
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• 1994

This study is to discuss the factors influenced on the removal efficiency of a high-strength organic wastewaters investigated using the polypropyrene media which appropriate to attach microorganism in the tube type fixed biofilter reactor. The results obtained in the experiment were as follows: 1. The kinetics of reaction rate (k') were 0.125, 0.135, 0.155 varing initial COD 720, 1280, 1630 mg/l in batch reactor. 2. In the range of pH 4.0 ~12.0 was obtained the removal efficiency of COD higher than 85%. It was proved that variation of pH (4.0 ~12.0) was nothing to do with the removal efficiency of substrate in continuous reactor. 3. Temperature to obtain removal efficiency of COD higher than 85% was 10 ~ 40$\circ$C. Removal efficiency of COD was no less than those at high temperature. 4. In the continuous reactor, the volumetric loading of COD for removal efficiency higher than 95% had to be 0.5~1.5 kg COD/m$^3$.d below. And then the HRT was 8 hrs. 5. In comparison with the activated sludge process, the tube type fixed biofilter process was excellent in removal efficiency of substrate and sludge production rate.

• 환경위생공학
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• 제14권3호
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• pp.130-138
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• 1999

The feasibility of municipal sewage sludge digestion was investigated by using thermophilic anaerobic sequencing batch reactor(ASBR). One-day settle time was enough for the high performance of solid-liquid separation. The conversion of semi-continuous mode to sequencing batch mode is easily achieved without any adverse effects, although the large amount of sludge equal to the volume ratio of 0.3~06 to reactor volume was added in the feed step of the start-up. The ASBRs had higher conversion capability of organics to biogas than the control reactor. Gas yields of the ASBRs were increased by the average of 50% over the control reactor across a range of hydraulic retention time(HRT)s from 10days to 5days. The thermophilic reactors showed higher gas production than mesophilic reactor. Removal efficiencies of organic matter exceeded 80% on the basis of supernatants, except that at the reactor. Solid-liquid separation was essential in the performance of the ASBR, especially, at the lower HFT. The ASBRs were highly efficient in the retention of activated biomass within the reactor. thus compensating for increased equivalent organic loading rate through increased solids retention times followed by the increased solids, while maintaining shorter HRTs.

• 환경위생공학
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• 제8권1호
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• pp.107-116
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• 1993

This study is conducted to investigate treatability by activated sludge process for wastewater from acetaldehyde manufacturing plant. The optimum hydraulic retention time in aeration tank for removal of high strength substrate were measured. The removal efficiency were checked out by hydraulic retention time : 35hr., 40hr. and 45hr., respectively. $COD_{Cr}$, like substances were removed in all hydraulic retention time zone directed for efficiency, but non-biodegradable substances were remained. $COD_{Cr}$ biomass loading was 0.81kg $COD_{Cr}/kgMLVSS$ . day at 35hr. of retention time, 0.34 kg$COD_{Cr}$/kg MLVSS . day at 40hr., and O.l9kg$COD_Cr$/kgMLVSS . day at 45hr. And the mean $COD_{Cr}$, removal efficiency was 65.5%, 81.6% and 83.0%, respectively. And also $COD_{Cr}$, volume loading was 1.01kg$COD_{Cr}/m^3$ day, 0.87kg$COD_{Cr}/m^3$ - day, and 0.79kg$COD_{Cr}/m^3{\cdot }$day, respectively. The basic design parameter obtained is as fallows. The value of Specific substrate removal rate coefficient (k), Yield coefficient(Y) and Decay coefficient($k_d$) was $0.0013day^{-1}$, $0.505kgMLVSS/kgCOD_{Cr}$ and $0.040day^{-1}$, respectively.