• 상하수도학회지
• /
• 제31권4호
• /
• pp.281-287
• /
• 2017

Mill scale, an iron waste, was used to separate magnetite particles for the adsorption of phosphate from aqueous solution. Mill scale has a layered structure composed of wustite (FeO), magnetite ($Fe_3O_4$), and hematite ($Fe_2O_3$). Because magnetite shows the highest magnetic property among these iron oxides, it can be easily separated from the crushed mill scale particles. Several techniques were employed to characterize the separated particles. Mill scale-derived magnetite particles exhibited a strong uptake affinity to phosphate in a wide pH range of 3-7, with the maximum adsorptive removal of 100%, at the dosage of 1 g/L, pH 3-5. Langmuir isotherm model well described the equilibrium data, exhibiting maximum adsorption capacities for phosphate up to 4.95 and 8.79 mg/g at 298 and 308 K, respectively. From continuous operation of the packed-bed column reactor operated with different EBCT (empty bed contact time) and adsorbent particle size, the breakthrough of phosphate started after 8-22 days of operation. After regeneration of the column reactor with 0.1N NaOH solution, 95-98% of adsorbed phosphate could be detached from the column reactor.

• 대한환경공학회지
• /
• 제28권1호
• /
• pp.1-6
• /
• 2006

본 연구에서 수행한 입상형의 발포 폴리스티렌을 이용한 고도처리 공정은 기존의 상용화되거나 개발중인 영양염류 처리공정에 비해 수리학적 체류시간을 상당히 줄일 수 있고 동절기에도 온도의 영향을 크게 받지 않는 장점을 가지고 있다. 도시하수를 이용하여 bench-scale 연구를 수행한 결과 T-N 제거효율의 경우 HRT 6 hr 및 4 hr에서 각각 약 55% 및 51%로서 HRT가 짧아졌을때 단지 약 4%의 처리효율 감소가 관찰되었다. 온도 영향에 있어서 여름철과 겨울철의 T-N 제거효율을 비교해본 결과 T-N 제거 효율이 각각 약 65% 및 54%로 관찰되어 여름철이 겨울철에 비해 약 11% 더 높은 효율이 관찰되었으며 겨울철 효율저하는 주로 암모니아성 질소의 질산화가 원활이 이루어지지 않았기 때문인 것으로 관찰되었다. 유입부하 및 C/N 비에 관한 연구에서는 유량 및 농도의 변화가 심한 하 폐수 처리에 있어서도 안정된 처리수질을 확보할 수 있었으며, C/N 비가 감소에 따른 처리효율 저하가 크지 않음을 관찰 할 수 있었다. 따라서 본 개발 시스템을 기존의 중 소규모 하수처리장에 적용할 경우 유입수내의 유기물을 최대한 활용하여 영양염류를 처리할 수 있을 것이라 기대된다.

• 한국유체기계학회 논문집
• /
• 제18권2호
• /
• pp.37-42
• /
• 2015

In the purpose of this study, we investigate the characteristics of the pilot-scale wastewater treatment system applied to BAF, MBR and IPNR as examining the removal efficiency of organic pollutants and operating factors in small decentralized wastewater treatment systems, and operating factors. For long-term operation period of more than nine months, pilot-scale plant operating results appeared very stable. This results were the removal efficiency of BOD was 80.3% above and removal efficiency of COD with an average of about 91.0%, satisfied the final effluent water quality standards. TN in the final effluents was the average concentration of 7.9 mg/L, was satisfactory water quality standards 10 mg/L of TN.

• 상하수도학회지
• /
• 제37권6호
• /
• pp.325-334
• /
• 2023

Membrane bioreactor (MBR) provides the benefits on high effluent quality and construction cost without the secondary clarification. Despite of these advantages, fouling, which clogs the pore in membrane modules, affects the membrane life span and effluent quality. Studies on the laboratory scale MBR were focused on the control of particulate fouling, organic fouling and inorganic fouling. However, less studies were focused on the control of biofouling and microbial aspect of membrane. In the full scale operation, most MBR produces high effluent quality to meet the national permit of discharge regulation. In this study, the performance and microbial community analysis were investigated in two MBRs. As the results, the performance of organic removal, nitrogen removal, and phosphorus removal was similar both MBRs. Microbial community analysis, however, showed that Azonexus sp. and Propionivibrio sp. contributed to indirect fouling to cause the chemical cleaning in the DX MBR.

• Advances in environmental research
• /
• 제12권2호
• /
• pp.77-93
• /
• 2023

The water can be contaminated by natural sources or by industrial effluents. One such contaminant is fluoride. Fluoride contamination in the water environment due to natural and artificial activities has been recognized as one of the major problems worldwide. Among the commonly used treatment technologies applied for fluoride removal, the adsorption technique has been explored widely and offers a highly efficient simple and low-cost process for fluoride removal from water. This review paper the recent developments in fluoride removal from surface water by adsorption methods. Studies on fluoride removal from aqueous solutions using various carbon materials are reviewed. Various adsorbents with high fluoride removal capacity have been developed, however, there is still an urgent need to transfer the removal process to an industrial scale. Regeneration studies need to be performed to more extent to recover the adsorbent in field conditions, enhancing the economic feasibility of the process. Based on the review, technical strategies of the adsorption method including the Nano-surface effect, structural memory effect, anti-competitive adsorption and ionic sieve effect can be proposed. The design of adsorbents through these strategies can greatly improve the removal efficiency of fluoride in water and guide the development of new efficient methods for fluoride removal in the future. This paper describes brief discussions on various low-cost adsorbents used for the effective removal of fluoride from water.

• 한국물환경학회지
• /
• 제22권2호
• /
• pp.250-257
• /
• 2006

The objective of this study is to propose an alternative process for the small sewage treatment plants in rural communities. A biofilter has been used for biological wastewater treatment, which is becoming the alternative to the conventional activated sludge system. The proposed process used in this study, which is packed with floating media (i.e. expanded polystylene), has advantages of biofilter system and alternative flow system and they are incorporated into one process. Pilot and bench scale studies were performed using domestic wastewater. In the results of pilot plant study, it was observed that the stable effluent water quality was achieved and it met the present effluent criteria of suspended solid (SS), organic matters, T-N and T-P. In the study for determination of the cycle of backwashing, it was observed that the cycle of backwashing depended on BOD loading rates of influents. In the BOD loading rates of $0.5kg\;BOD/m^3{\cdot}day$ and $1.0kg\;BOD/m^3{\cdot}day$, the backwashing cycle of 28 hour and 16 hour were needed, respectively. The optimum backwashing time was 120~80 seconds at the media expansion rate of 50%. In the removal of SS, organic matters, T-N and T-P, SS removal was rather achieved by physical filtration than biological mechanism and the removal of organic matters except for SS, T-N and T-P were mainly rather achieved by biological mechanism than physical filtration. In bench-scale study, the effects of recirculation rate was investigated on removal of SS, TCOD, T-N and T-P. It was observed that the recirculation made removal efficiencies of SS, TCOD, T-N and T-P increased. Especially, in T-N removal, the increase of T-N removal efficiency of 40% was observed in the reicirculation rate of 1Q compared with 0Q.

• 상하수도학회지
• /
• 제36권2호
• /
• pp.121-134
• /
• 2022

In this study, the removal efficiency of PFCs(perfluorinated compounds) in the GAC(granule activated carbon) process based on the superheated steam automatic regeneration system was investigated in laboratory scale and pilot-scale reactor. Among PFCs, PFHxS(perfluorohexyl sulfonate) was most effectively removed. The removal efficiency of PFCs was found to be closely related to the EBCT, and the removal efficiencies of PFOA(perfluorooctanoic acid), PFOS(perfluorooctyl sulfonate), and PFHxS were 43.7, 75, and 100%, respectively, under the condition of EBCT of 6 min. Afterward, PFOA, PFOS, and PFHxS exhibited the earlier breakthrough time in the order. After that, GAC was regenerated, and the removal efficiency of the PFCs before and after regeneration was compared. As a result, it was shown that the PFCs removal efficiency in the regenerated GAC process were higher, and that of PFOA was improved to 75%. The findings of this study indicate the feasibility of the superheated steam automatic regeneration system for the stable removal of the PFCs, and it was verified that this technology can be applied stably enough even in field conditions.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
• /
• pp.199-202
• /
• 2004

In this study the field-scale tests were performed in which in-situ E/K remediation technologies were applied, and then the results were present. For traditional E/K remediation method the efficiency of remediation is not large, but the enhanced method with citric acid significantly increases the removal efficiency. Also EDTA, reported as a good enhancement agent for removal of heavy metals, is similar to that of citric acid. Therefore citric acid is preferred rather than EDTA in view of the cost on the contaminant removal per unit concentration.

• 한국환경보건학회지
• /
• 제35권2호
• /
• pp.116-123
• /
• 2009

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus by the variation of aeration time in four sequencing batch reactors (SBRs). In R1 which has the shortest aeration time as 1 h, MLVSS concentration in reactor decreased by the wash-out of biomass because of the poor sedimentation. The TOC removal efficiencies were almost similar in 3 reactors except R1. At the low aeration time as 1 h, the nitrification was severely inhibited by the deficiency of oxygen. ${NH_4}^+$-N removal efficiency was decreased by the decrease of aeration time. At the aeration time over 2 h, the phosphorus removal efficiency was not affected by the variation of aeration time. The nitrification was inhibited but the phosphorus release and uptake was not inhibited by the decrease of low aeration time. Therefore, we can see that the phosphorus removal microorganisms are superior to nitrification microorganisms in oxygen utilization.

• 상하수도학회지
• /
• 제18권6호
• /
• pp.807-813
• /
• 2004

Wastewater was treated by two different treatment processes; activated sludge process and advanced wastewater treatment process (KNR process) using lab-scale experiment. Two treated wastewater showed good treatment efficiency of organic matter removal, up to 90% removal. Nitrogen and phosphorus were not effectively removed though activated sludge process, while KNR process showed good removal efficiency of nitrogen and phosphorus; 56% nitrogen removal and 95% phosphorus removal. KNR process showed better removal efficiency of organic matter, nitrogen, and phosphorus compared to activated sludge process. Organic matter characterization was tracked though measurement of UV scan, SUVA, and XAD fractionation. Treated wastewater showed higher SUVA value than wastewater influent, indicting less aromatic characteristic of organic matter. XAD fractionation showed hydrophilic fraction decreased though wastewater treatment, suggesting microbes preferentially digest hydrophilic and aliphatic molecules rather than hydrophobic and aromatic molecules of organic matter.