• 상하수도학회지
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• 제8권1호
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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 Korean Society for Atmospheric Environment
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• 제21권E2호
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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.

• 기술사
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• 제18권3호
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• pp.28-35
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• 1985

As the paper industry consumes much water in process and discharge wastewater containing suspended solid and COD(chemical oxygen demand), relevant law against this discharge has been set up to limit the total containment of COD in discharge. This study has been carried out to improve the treatment method for the soluble COD in wastewater produced during the process of paste-board production, which is made of semichemical pulp and waste paper. Applicated methods are, O$_2$AS : O$_2$ activated sludge process DAS : Deep well activated sludge process SAS : standard activated sludge process and proper combination of DAS and SAS 1) As a result of this experiment, we get the following conclusion between in COD sludge loading "X" and COD removable rate in the process of treating waste-water. COD removable rate(％)=(0.778+0.0146/X)${\times}$100(％)……(7) 2) In case that the COD sludge loading is high, it has been cleared out that the COD removable rate shall become low due to unknown unsoluble substances contained in the process. Meanwhile, to increase the efficiency rate of treatment, it is thought to be necessary, to provide long-time contacts with activated sludge. 3) Once the COD of original waste-water and the target COD of treated water are decided, COD sludge loading is obtained from equation(7), and capacity of aeration tank in the effective systems such as O$_2$AS, DAS, to bet the required COD removable rate can be decided. Therefore the choice among SAS, O$_2$AS, DAS methods is made in consideration of required COD removable rate and allowable installation area. 4) In the sedimentation tank with sludge bulking, it is possible to increase the COD removable rate by 3～7％ but still there exist many obstacles to manage this operation.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 제6회 하계 Workshop (98 한국막학회, 국립환경연구원 국제 Workshop, 수자원 보전과 막분리 공정)
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• pp.113-133
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• 1998

In activated sludge process, sludge settling condition is affected by organic loading rate or operation condition, and if settling condition is getting worse, it is common that overall process fails due to wash-out of biomass causing low concentration in the aeration tank. Also activated sludge process has such several problems as requiring large area, consuming a lot of power and producing large volume of sludge. Increased public concern over health and the environment combined with a strong desire to reduce capital, operating and maintenance costs, have created a need for innovative technologies for building new high quality effluents which vail meet 21st century crkeria. MBR(Membrane Bioreactor) process consists of a biological reactor and ultrafiltration(UF) membrane system that replaces the conventional clarifier of an activated sludge process. The main operating advantages of this system are that the quality of the effluent is independent of the settleability of the mixed liquor and that the effluent is free of suspended solids in any operating condition. It is possible to eliminate clarifier and to reduce the volume of aeration tank because it can afford to accumulate high biomass concentration in the bioreactor(20, 000~30, 000mg/L), which would not be possible in a conventional activated sludge process. Therefore, this process reduces overall treatment plant area. In addition to those advantages, Longer SRT condition enables higher sludge digestion in MBR process so the sludge volume produced is 50 to 70% lower than that of conventional activated sludge process There are two kinds of MBR process according to the allocations of membrane. One is cross flow type MBR of which module is located outside of the bioreactor and mixed liquor is driven into the membrane module. The other is submerged type MBR process of which module is submerged in the bioreactor and mixed liquor is generally sucked from the lumen side. addition to that the cake layer is often removed by the uplifting flow of bubbling air. A submerged MBR process is superior to a crossflow MBR in regard to the power consumption because suction pressure of a submerged MBR is generally lower than that of a crossflow MBR which has recirculation pump. A submerged MBR, therefore, has the potential to be applied to small wastewater treatment plants that need low cost treatment systems.

• 청정기술
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• 제15권4호
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• pp.265-272
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• 2009

본 연구에서는 하수슬러지에서 만든 활성탄을 이용하여 벤젠에 대한 정지(static)흡착실험을 수행하였다. 7.999 kPa에 이르는 압력 범위 내에서 온도 조건을 변화시켜 가며 303.15, 318.15, 333.15 K에서 흡착실험을 진행하였다. 등온흡착곡선은 Langmuir isotherm, Freundlich isotherm, Toth isotherm을 적용하여 비교하였다. 벤젠의 흡착량(q)을 fitting한 결과 Langmuir isotherm과 Toth isotherm으로 fitting한 등온흡착 곡선의 정확도가 높은 것으로 나타났다. 그리고 Langmuir isotherm의 $q_{max}$ 값을 이용하여 흡착제의 흡착량을 비교하였다. 또한, 하수슬러지 활성탄과 상용활성탄의 세공 발달 여부를 비교하기 위해 SEM image를 관찰하였다. SEM image 관찰 결과, 국내외 상용활성탄(DARCO A.C., SPG-100 A.C.)이 하수슬러지 활성탄에 비해 세공발달 정도가 우수하며, 세공발달 정도가 우수한 국내외 상용활성탄(DARCO A.C., SPG-100 A.C.)이 하수슬러지 활성탄에 비해 벤젠흡착량(q)이 높은 것을 확인할 수 있었다. 그러나 실온조건인 303.15K에서 하수슬러지의 최대 벤젠흡착량($q_{max}$)은 국내 상용활성탄(SPG-100 A.C.)의 최대 벤젠흡착량($q_{max}$)과 대등한 수치로 나타났으므로 하수슬러지 활성탄의 상용화 가능성을 검증할 수 있었다.

• 한국환경보건학회지
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• 제33권4호
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• pp.338-343
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• 2007

Chlorine inhibition on the denitrifing activity of activated sludge treating dairy wastewater was investigated in this study. Filamentous bulking was caused artificially by a sudden load of feed and monitored by measuring sludge volume index. In cases of the activated sludge and bulking sludge which were contacted with chlorine as $7.5\;mgCl_2/gVSS/day$ for bulking control, the decreases of specific denitrification of $32.2{\sim}40.4%\;and\;43.5{\sim}46.5%$ were shown in comparison to the control group which was not reacted with chlorine, respectively. In continuous operation, it was observed that the removal efficiency of total nitrogen was more susceptible to chlorine than the removal efficiency of total phosphorus.

• 생명과학회지
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• 제33권1호
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• pp.82-90
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• 2023

하수와 산업폐수를 처리하는데 생물학적 공정이 전세계적으로 이용된다. 생물학적 공정은 복합미생물로 구성된 슬러지를 사용한다. 슬러지 미생물이 성장함에 따라 폐수처리공정에서는 잉여슬러지가 발생한다. 잉여슬러지의 일부는 미생물을 보충하기 위해 폐수처리공정에 반송되지만 나머지는 폐기물로서 처리된다. 매년 전세계적으로 폐수발생이 증가함에 따라 폐수처리장의 수도 증가하여 많은 양의 폐슬러지가 생산된다. 따라서 폐슬러지에 대한 관리와 처리가 중요하다. 폐슬러지 처리비용은 폐수처리장 총운영비의 50-60%를 차지한다고 보고되었다. 슬러지 분해기술은 폐슬러지의 부피를 최소화하고 유용한 성분(예, P, N, 용해성 유기물)을 회수할 수 있는 새로운 기술이다. 물리적, 화학적, 그리고 생물학적 처리 또는 복합 처리에 기반을 둔 다양한 슬러지분해방법들이 개발되었다. 본 총설은 슬러지 분해방법들 중에서 비교적 덜 연구된 산 가수분해에 의한 슬러지 분해에 대해 중점적으로 다루었다. 본 총설에서 다룬 정보는 폐슬러지 처리를 위한 더 나은 기술을 개발하고 이식하는데 유용하게 사용될 것이다.

• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1704-1707
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• 2007

Monitoring of the phage-host system of Microlunatus phosphovorus indigenous in activated sludge was attempted. A laboratory-scale activated sludge process was operated for 5 weeks with synthetic wastewater. The phage-host system population in the process was monitored by plaque assay and FISH methods at every 3 days. During the process operation, the phage-host system populations were more or less steady, except for 1 week in the middle of the operation. In that period, initially M. phosphovorus decreased significantly and its lytic bacteriophages increased, and then M. phosphovorus increased back to its original level while its lytic bacteriophages decreased. This observation suggests that lytic bacteriophages should be considered as one of the biological factors affecting the bacterial population dynamics in activated sludge processes.

• Journal of Microbiology and Biotechnology
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• 제23권5호
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• pp.719-723
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• 2013

Nitrification in wastewater treatment emits a significant amount of nitrous oxide ($N_2O$), which is one of the major greenhouse gases. However, the actual mechanism or metabolic pathway is still largely unknown. Selective nitrification inhibitors were used to determine the nitrification steps responsible for $N_2O$ emission with activated sludge and enriched nitrifiers. Allylthiourea (86 ${\mu}M$) completely inhibited ammonia oxidation and $N_2O$ emission both in activated sludge and enriched nitrifiers. Sodium azide (24 ${\mu}M$) selectively inhibited nitrite oxidation and it led to more $N_2O$ emission than the control experiment both in activated sludge and enriched nitrifiers. The inhibition tests showed that $N_2O$ emission was mainly related to the activity of ammonia oxidizers in aerobic condition, and the inhibition of ammonia monooxygenase completely blocked $N_2O$ emission. On the other hand, $N_2O$ emission increased significantly as the nitrogen flux from nitrite to nitrate was blocked by the selective inhibition of nitrite oxidation.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제1권1호
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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.