• 한국유체기계학회 논문집
• /
• 제18권2호
• /
• pp.43-47
• /
• 2015

As water quality regulations have tightened, many studies to improve wastewater treatment efficiency have been performed. In this study, magnetite powder was used to maintain a high concentration of MLSS in lab-scale wastewater treatment system. After magnetite powder injection, MLSS concentration was above 8,000 mg/L and it was 3.2 times higher than control group(2,500 mg/L). In addition, nitrogen removal efficiency and phosphorus removal efficiency comparing with the control group was increased 20.5% and 11%, respectively.

• 한국환경보건학회지
• /
• 제31권2호
• /
• pp.152-159
• /
• 2005

Laboratory scale experiments were conducted to study the applicability, and to compare the performance of two types of sequencing batch reactor (SBR)systems, a conventional SBR and sequencing batch biofilm reactor (SBBR) on the biological nitrogen and phosphorus removal. The nitrification rate in SaR was higher than that in SBBR both in high influent TOC concentration. The denitrification was completed at the first non-aeration period in SBR, however, the additional non-aeration period should be installed or the first aeration period should be extended more in order to complete the nitrogen removal in SBBR. The time at the first aeration period was more needed as about 4-5 h in order to uptake all the released $PO_4^{3-}\;-P$ at the first non-aeration period. SBBR needed more operation time, especially the first aeration time, than SBR at the high influent TOC concentration in order to complete nitrogen and phosphorus removal.

• 한국환경보건학회지
• /
• 제23권4호
• /
• pp.127-132
• /
• 1997

The characteristics of the ozone treatments of phenol were studied in a laboratory scale wastewater treatment system. The ozone treatment of wastewater was carried out in a batch-type reactor. The initial pH of wastewater(7-10), volumetric flow rate(1-2l/min) and ozone concentration(20~30 mg/l) of aerating gas were considereal as experimental variables in the ozone treatment. Phenol was decomposed easily by the ozone in a batch treatment, where the rate determining step was the COD removal that is decomposition of intermediates formed by the ozonation of phenol. Phenol decomposition and COD removal could be expressed by the first order reaction for the phenol concentration and COD, respectively. Rate constants of phenol decomposition and COD removal increased with the initial pH, volumetric flow rate and ozone concentration of aeration gas. Under the present experimental condition, their relationships could be given by for the phenol decomposition $k'=4.46\times 10^{-9}[pH]_o ^{3.94}[O_3]^{1.42}Q_{O3}^{1.57}$ for the COD removal $k=2.46\times 10^{-10}[pH]_o ^{5.19}[O_3]^{1.15}Q_{O3}^{1.19}$

• Advances in environmental research
• /
• 제3권4호
• /
• pp.283-292
• /
• 2014

Iron precipitating organisms play a significant role in the formation of ferric hydroxide precipitate, which acts as strong adsorbent for toxic metal. In this respect four different iron precipitating cultures were isolated from Hutti gold mine surface winze water sample on citrate agar medium. The best isolate was screened out for metal removal study on the basis of fast visual iron precipitation. The selected isolate was identified as Enterobacter sp. based on routine biochemical tests and Biolog GN microplate results and as Enterobacter cloacae subsp. dissolvens by 16S rRNA gene sequence analysis (GenBank accession number EU429448). Influence of medium composition, medium initial pH, the influence of inoculum size, effect of various media and ferric ammonium citrate concentration were studied on metal removal in shake flask experiments. Under the optimized conditions studied, E. cloacae showed $94{\pm}2$, $95{\pm}2$ and $70{\pm}2%$ of cadmium, copper and mercury removal from a simulated waste in shake flask studies. In lab scale column reactor more than 85% of copper and mercury removal was achieved.

• Environmental Engineering Research
• /
• 제15권1호
• /
• pp.3-7
• /
• 2010

To better understand the ecology of tetrade forming organisms (TFOs) floating in a large amount of dairy wastewater treatment plant (WWTP) effluent (sequencing batch reactor [SBR]) during the inefficient phosphorus (P) removal process of an enhanced biological P removal system, the TFOs from the effluent of a full scale WWTP were separated and attempts made to culture the TFOs in presence/absence of oxygen. The intact TFOs only grew aerobically in the form of unicellular short-rods. Furthermore, to identify the intact TFOs and unicellular short-rods the DNAs of both were extracted, analyzed using their denaturing gradient gel electrophoresis (DGGE)-profiles and then sequenced. The TFOs and unicellular short-rods exhibited the same banding pattern in their DGGE-profiles, and those sequencing data resulted in their identification as Acinetobacter sp. The intact TFOs appeared in clumps and packages of tetrade cells, and were identified as Acinetobacter sp., which are known as strict aerobes and efficient P-removers. The thick layer of extracellular polymeric substance surrounding Acinetobacter sp. may inhibit phosphate uptake, and the cell morphology of TFOs might subsequently be connected with their survival strategy under the anaerobic regime of the SBR system.

• 한국물환경학회지
• /
• 제18권2호
• /
• pp.141-150
• /
• 2002

Two-stage membrane bioreactor using submerged hollow fiber membrane was applied in laboratory scale to treat nitrogen and phosphorus of domestic wastewater. Alum as the flocculant and adsorbent was added into the anaerobic basin of two-stage membrane bioreactor and mixed liquid of aerabic basin was recycled to the anaerobic basin for the purpose of nitrogen removal. Experiment was carried out to find removal efficient of phosphorous and nitrogen components in the mixed liquid, and the stability of the permeate flux and pressure of two-stage membrane bioreactor. In case of alum was added as the flocculant and adsorbent into the anaerobic basin, soluble phosphorus removal efficient was relatively higher and total permeate resistance(Rtot) was more increased out nitrogen removal efficient was lower as the result of lack of alkalinity and insufficient nitrification process than the case of alum was not added.

• 실내환경 및 냄새 학회지
• /
• 제17권4호
• /
• pp.381-388
• /
• 2018

In this study, various conditions and phenomena that occur in the process of removing odorous VOCs by using electrolyzed oxidant were examined. The formation of hypochlorous acid, which is an oxidant produced by electrolysis, was investigated and the properties of the oxidizing agent used to decompose toluene, xylene, and cyclohexane were investigated. As a result, it was found that the production rate and the final concentration of the oxidizing agent increased with the current density. It was found that the degree of removal varies depending on the property of each pollutant. Interestingly, in the batch experiments in which the pH of the produced oxidant was controlled, it was found that the degree of elimination varied depending on the pH of the substance. These results suggest that the difference in the concentration and distribution of hypochlorous acid (HOCl) and hypochlorite ($OCl^-$) due to the pH change leads to the difference in oxidizing power on the oxidation characteristics of each substance. Styrene and terpineol showed better degradation characteristics than toluene and xylene in odorous VOC removal experiments by spraying electrolytic oxidant using a lab-scale continuous reactor. In conclusion, the removal of odorous VOCs by the electrolytic oxidant can have various applications in that it can oxidize pollutants of various spectra.

• 상하수도학회지
• /
• 제8권3호
• /
• pp.9-18
• /
• 1994

활성슬러지 공정을 이용하여 Kraft 펄프공장에서 배출되는 유출수에 잔류하는 만성독성의 제거가능성을 평가하기 위하여 pilot plant를 운전하였다. 독성 이외에도 폐수내의 BOD, SS, resin과 fatty acids, 색도, 그리고 AOX와 같은 오염물질의 제거효과도 측정되었다. Pilot plant는 정상상태에서 약 10주 동안 운전되었으며 운전기간 동안의 평균 F/M 비율은 0.28, 그리고 sludge age는 8.4일로 계산되었다. 평균 MLSS 농도는 4,309mg/l이었으며 이중 휘발성 물질은 57%이었다. 운전기간 동안, BOD 제거계수(k)는 $30^{\circ}C$에서 8.2/일 이었으며 BOD 제거율은 full-scale 운전시보다 3~6% 정도 낮은 84%로 나타났다. 활성슬러지 유출수의 만성독성 시험은 Dinnel 방법과 BML 방법이 활용되었으며, 시험결과 pilot plant 활성슬러지 시스템에서도 효율적인 운전을 통하여 90% 이상의 독성제거가 가능함을 알 수 있었다. Pilot plant의 진 공정을 통해서 색도와 AOX의 제거는 매우 미미하였으나 resin과 fatty acids는 뛰어난 제거율을 나타내었다.

• 청정기술
• /
• 제8권2호
• /
• pp.77-83
• /
• 2002

본 연구는 국내하수처리장에서 발생되는 하수내 질소와 인을 생물학적 영양소 제거공정을 이용하여 효율적으로 처리할 수 있는 설계 및 운전기술을 정립하는데 목적을 두고 있다. 혐기조 전단에 설치한 내생탈질조(Endogenous nitrate respiration, ENR)는 외부탄소원 없이 내생으로 반송슬러지내 포함된 질산성질소를 연속적으로 탈질시켜 질산성질소를 3mg/L 이하로 줄여 혐기조로 이송시킨다. 공정에 대한 성능 실험은 파이롯에서 수행하였다. 실험결과 운전기간동안 유입수내 TCOD/TP 비는 40에서 60범위를 보였고 TCOD/TKN 비는 5~7을 유지하였다. 유출수는 총질소는 10에서 12mg/L을 유지한 반면 총인은 최저 1mg/L을 가리켰다. 혐기조에서 $SP_{rel}/SCOD_{rm}$는 0.13에서 0.17을 유지하였다. 실험실규모에서는 ENR 반응률을 산정하였는데 0.042에서 $0.057gNO_3-N/gMv.d.$를 보였다. 이들 인자들은 생물학적 영양소제거공정을 설계하는데 유용하게 이용될 수 있고 ENR 반응은 저농도 하수에서 질소, 인 처리시 효과적임을 알 수 있었다.

• 상하수도학회지
• /
• 제35권1호
• /
• pp.1-14
• /
• 2021

Eutrophication and algal blooms can lead to increase of taste and odor compounds and health problems by cyanobacterial toxins. To cope with these eco-social issues, Ministry of Environment in Korea has been reinforcing the effluent standards of wastewater treatment facilities. As a result, various advanced phosphorus removal processes have been adopted in each wastewater treatment plant nation-widely. However, a lot of existing advanced wastewater treatment processes have been facing the problems of expensive cost in operation and excessive sludge production caused by high dosage of coagulant. In this study, the sedimentation and dissolved air flotation (SeDAF) process integrated with sedimentation and flotation has been developed for enhanced phosphorus removal in wastewater treatment facilities. Design and operating parameters of the SeDAF process with the capacity of 100 ㎥/d were determined, and a demonstration plant has been installed and operated at I wastewater treatment facility (located in Gyeonggi-do) for the verification of field applicability. Several empirical evaluations for the SeDAF process were performed at demonstration-plant scale, and the results showed clearly that T-P and turbidity values of treated water were to satisfy the highest effluent standards below 0.2 mg/L and 2.0 NTU stably for all of operation cases.