• Title/Summary/Keyword: waste activated sludge(WAS)

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Electrosorption of Uranium Ions in Liquid Waste

  • Lee, Hye-Young;Jung, Chong-Hun;Oh, Won-Zin;Park, Jin-Ho;Shul, Yong-Gun
    • Carbon letters
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    • v.4 no.2
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    • pp.64-68
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    • 2003
  • A study on the electrosorption of uranium ions onto a porous activated carbon fiber (ACF) was performed to treat uraniumcontaining lagoon sludge. The result of the continuous flow-through cell electrosorption experiments showed that the applied negative potential increased the adsorption kinetics and capacity in comparison to the open-circuit potential (OCP) adsorption for uranium ions. Effective U(VI) removal is accomplished when a negative potential is applied to the activated carbon fiber (ACF) electrode. For a feed concentration of 100 mg/L, the concentration of U(VI) in the cell effluent is reduced to less than 1 mg/L. The selective removal of uranium ions from electrolyte was possible by the electrosorption process.

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Biological Hydrogen Production from Mixed Organic Waste of Food and Activated Sludge by Pre-treatment (음식물쓰레기와 전처리한 폐활성슬러지의 혼합비율에 따른 생물학적 수소생산)

  • Lee, Jun-Cheol;Kim, Jae-Hyung;Choi, Kwang-Keun;Pak, Dae-Won
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.9
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    • pp.1044-1050
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    • 2007
  • In this study, Bio-hydrogen is produced from organic waste mixtures containing food waste and waste activated sludge (WAS). The effects of different operational factor on hydrogen production, including various solubilization methods for pretreatments of WAS, pH and different ratios of food waste and WAS, were investigated. The highest hydrogen production values are obtained as 4.3 mL $H_2/g$ $VS_{consumed}$ in the case of applying the mixed pre-treatments of alkali and ultrasonic. The pH value in bio-reactor increased from 4 to 8 after the ultrasonic treatment with alkali and the hydrogen yield touched its highest value in the pH range of 5.0 to 5.5. Similarly, the hydrogen production reached the level of 13.8 mL $H_2/g$ $VS_{consumed}$ using the same pre-treatment method from the mixture of food waste and WAS. The ratio of 2 : 1 produced a maximum amount of hydrogen of 5.0 L $H_2/L/d$. The amount of volatile fatty acids(VFAs) including acetate, propionate and butyrate, were also varied considerably. Propionate decreased consistently with rising of hydrogen while butyrate comparing to acetate relatively increased in the effluent.

Flocculation of microalgae using extracellular polymeric substances (EPS) extracted from activated sludge

  • Dong, Dandan;Seo, Dongmin;Seo, Sungkyu;Lee, Jae Woo
    • Membrane and Water Treatment
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    • v.9 no.3
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    • pp.147-153
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    • 2018
  • This study investigates the role of microbial extracellular polymeric substances (EPSs) as bioflocculants to harvest microalgae (water-microalgae separation). The EPS extracted from waste activated sludge (WAS) by heat extraction were fractionated into soluble EPS (S-EPS), loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) forms. All the EPSs facilitated the flocculation of microalgal cells from stable growth medium. Of those EPSs, the TB-EPS showed the highest flocculating activity (FA) resulting in the substantial decrease in the amount of EPS added in terms of total organic carbon (TOC) during flocculation. The FA of microalgae was improved with the increase in TB-EPS dose, however, excessive dose of TB-EPS adversely affected it due to destabilization. Both LB- and TB-EPS could be utilized for flocculating microalgae as a sustainable option to the existing chemical-based flocculants. In addition to the conventional assessments, the effectiveness of the two bioflocculants for floc forming was also confirmed using a novel assessment of lens-free shadow imaging technique (LSIT), which was firstly applied for the rapid and quantitative assessment of microalgal flocculation.

Pilot-scale Study for Pulse Power Pretreatment of Waste Activated Sludge (Pulse Power를 이용한 폐활성슬러지 전처리의 파이럿 규모 연구)

  • Yoo, Hee Chan;Hong, Seung Mo;Choi, Han Na
    • Journal of the Korea Organic Resources Recycling Association
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    • v.13 no.3
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    • pp.71-81
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    • 2005
  • Anaerobic digestion is employed worldwide as the oldest and most important process for sludge stabilization. An additional advantage is the production of methane during anaerobic digestion. However, the waste activated sludge(WAS) has poor anaerobic degradability and less gas production due to the cell wall of bio-solid. In order to improve and enhance stabilization and dewatering of the WAS, a number of pretreatment processes have been developed and investigated. In this research, a pilot-scale study of pulse power pretreatment was performed to improve anaerobic degradability and dewaterability of the WAS. A pilot plant was designed and operated based on a previous laboratory study. Change of the sludge characteristics by pulse power pretreatment was estimated to assess the increasing soluble organics. The increased soluble organics could be used as a good substrate in the anaerobic digesion process. Gas production and methane potential of the anaerobic digestion were estimated as the parameters of anaerobic degradability. For evaluation of the dewaterability of pretreated WAS, capillary suction time(CST) and specific resistance were measured. The efficiency of energy recovery was also estimated by calculating energy balance.

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Performance Enhancement of Anaerobic Treatment of Waste Sludge by Chemical Pretreatment (화학적 전처리를 통한 혐기성 슬러지 처리효율의 향상)

  • 허준무;박종안;손부순
    • Journal of environmental and Sanitary engineering
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    • v.13 no.1
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    • pp.16-25
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    • 1998
  • Laboratory-scale experiment using anaerobic fluidized bed reactor was carried out to investigate the prehydrolysis step with caustic soda on the treatment efficiency of anaerobic sludge treatment, since the overall rate-limiting step for the complete anaerobic digestion of sludge was the hydrolysis step by extracellular bacterial enzymes of insoluble polymeric molecules. Reactors received a sludge which had not been pretreated, a 50-50 mixture of pretreated and untreated sludge, and the fully pretreated sludge. Hydraulic retention time of 10, 5, 2.5 days and 1 day were applied with an respective equivalent organic loading rate of 1.17, 2.23, 4.17, 11.24 gCOD/L/d. Reactor with the untreated sludge did not archieve adequate digestion even at the HRT of 5 days, and reactor, which received the 50-50 mixture, operated well at the HRT of 5 days, but began to show signs of unstable digestion at the HRT of 2.5 days. While, reactor, which was fed the hydrolyzed sludge, operated reasonably well at the 2.5 days, but was showing somewhat decrease in removal efficiencies. Results, therefore, have substantiated that the limiting reaction in the anaerobic treatment process is hydrolysis. The soluble COD did not significantly accumulate in the reactor as organic acid form, even when they were highly stressed. It was believed that this resistance to a build-up of organic acids and soluble COD behavior was mainly due to the maintenance of the methane bacteria in the fixed-film system which prevents washout as the organic loading increased. The anaerobic fluidized bed reactor was therefore effective for the digestion of waste activated sludge at short HRT.

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Fuzzy Expert System for Bulking Prediction and Mitigation in the Activeated Sludge Process

  • Nam, Sung-Woo;Kim, Jung-Hwan-;Sung, U-Kyung;Lee, Kwang-Soon-
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1993.06a
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    • pp.1102-1105
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    • 1993
  • A fuzzy expert system for prediction and mitigation of sludge bulking was developed for an activated sludge process which treats waste water from a food industry. The developed system is able not only to infer the degree of progress of sludge bulking but also to generate remedial operation guides which may be sent to the local controllers as remote set points. One of the important consequences through this study is the BI (Bulking Index) inferred by the bulking prediction expert system was found to have a close correlation with the SVI (Sludge Volume Index) which is a practical measure of degree of bulking but needs tedious chores for its measurement.

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Pretreatment Characteristics and Specific Methanogenic Activity of Municipal Sewage Sludge by Dual Frequency Sonication (이중주파수 초음파를 이용한 도시하수슬러지의 전처리 특성 및 비메탄활성도에 관한 연구)

  • Jung, Byung-Gil;Jang, Seong-Ho;Sung, Nak-Chang
    • Journal of Environmental Science International
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    • v.16 no.2
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    • pp.211-218
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    • 2007
  • The objectives of this study have been carried out to investigate the solubilization of municipal sewage sludge by single and dual frequency ultrasonic pretreatment, and the methane production characteristics of pretreated sewage sludge by specific methanogenic activity test for sewage sludge reduction. The waste activated sludge was collected from thickened tank of Suyoung sewage treatment plant in Busan city, and its concentration was adjusted to 1.0% total solids. Ultrasonic frequency was varied 15, 20, 15+20 kHz, and acoustic density was used a maximum 176W/L. The dual frequency ultrasonic pretreatment was found to be more effective than single frequency ultrasonic in the solubilization rate and methane production. The $SCOD_{Cr}/TCOD_{Cr}$, rate were 15.2%, 13.9%, 17.0% with single frequency of 15 kH2, 20 kHz, dual frequency of 15+20 kHz, respectively. The application of dual frequency ultrasound for sewage sludge pretreatment can be interest for sewage treatment plants having problems in sludge treatment and disposal.

The Mathematical Kinetics for Activated Sludge Process

  • Han, Ungjun;Lim, Jaemyung
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.14 no.1
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    • pp.43-54
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    • 1978
  • A complete mixing aeration only activated sludge system was operated for the mathematical analysis. The unit, 4 liter capacity, was fed by an industrial waste containing a much amount of glutamic acid in a laboratory study. The observed results were compared with the generated dilta presented by the previous mathematical models.

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A Study on the pretreatment of Activated Sludge for Bio-hydrogen Production process (생물학적 수소생산 공정 개발을 위한 오니 슬러지 전처리에 대한 연구)

  • Kim Dong Kkun;Kim Ji Seong;Kim Ho Il;Lee Yu Na;Pak Dae Won
    • 한국생물공학회:학술대회논문집
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    • 2004.07a
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    • pp.21-33
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    • 2004
  • In this study, Anaerobic sewage sludge in a batch reactor operating at $35^{\circ}C$ was used as the seed to investigate the effect of pretreatments of waste activated sludge and to evaluate its hydrogen production potential by anaerobic fermentation. Various pretreatments including physical, chemical and biological means were conducted to utilize for substrate. As a result, SCODcr of alkali and mechanical treatment was 15 and 12 times enhanced, compared with a supernatant of activated sludge. And SCODcr was 2 time increase after re-treatment with biological hydrolysis. Those were shown that sequential hybridized treatment of sludge by chemical & biological methods is most efficient process for sludge treatment. The pre-treatment activated sludge was tested to conform hydrogen production potential in batch experiments. When buffer solution was added to the activated sludge, hydrogen production potential increased as compare with no addition.

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Biological Evaluation for Characteristics of Leachate Toxicity from Municipal Solid Waste Landfill (생물학적 방법에 의한 도시생활폐기물 매립지의 침출수 독성특성 평가)

  • 황인영;류경무
    • Environmental Analysis Health and Toxicology
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    • v.11 no.1_2
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    • pp.31-39
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    • 1996
  • Leachate from municipal solid waste (MSW) landfill, effluent from leachate treatment plant, and ground water sample from a monitoring well near landfill site were tested for an acute toxicity. Microtox toxicity test was used for testing the acute toxicity of leachate and other samples. EC$_{50}$ values which a concentration of pollutant for reducing 50% light output from luminescent bacteria, Photobacterium phosphoreum were determined to assess the toxicity of pollutants as well as the relative toxicity. In addition, characteristics of leachate were studied and compared to those of phenol and pentachlorophenol (PCP) which are typical aquatic toxic pollutants. For leachate, EC$_{50}$ for 30 min incubation was 10.8%, while for phenol and PCP, 46 ppm and 1.2 ppm, respectively. the relative toxicity of treated leachate by in situ aeration with activated sludge was reduced to more than 75% of toxicity of the untreated leachate. Microtox toxicity test was failed to figure out EC$_{50}$ values for groundwater from a monitoring well since the relative toxicity of the unconcentrated sample was too low to estimate EC$_{50}$. Addition of activated carbon to leachate was reduced the relative toxicity. The reduction Pattern of the relative toxicity of leachate by mechanical aeration was similar to that of PCP, but different from that of phenol. These findings suggest that the toxicity of leachate may come from PCP-like toxic compounds rather than phenol-like one. In conclusion, the process of aeration with activated sludge might be very important to reduce the environmental toxicity of leachate. And Microtox test could be a reasonable bioassay for screening and monitoring the environmental toxicity of leachate from municipal solid waste landfill as well as for determining the reduction efficiency of the leachate toxicity by various treatment processes in leachate treatment plant.

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