• Applied Biological Chemistry
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• 제45권1호
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• pp.25-29
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• 2002

활성슬러지에 의한 생물학적 폐수처리에 있어 주된 관리인자는 유기물의 효율적인 제거와 슬러지의 침강성을 일정치 이하로 유지하는 것이다. 식품폐수의 하나인 고농도의 대두가공폐수를 일반적인 활성슬러지법을 적용한 결과 최적 F/M비(food-to-microorganism ratio)는 0.24(kg-BOD/kg-MLVSS day)였으며 그 이상의 농도인 0.48(kg-BOD/kg-MLVSS day)에서는 슬러지 팽화현상이 발생하여 고농도의 식품폐수처리에는 효율적이지 못하였다. 이를 개선하기 위하여 응집보조제(NaOH)를 활용하여 유입폐수의 pH를 9.0으로 조절한 결과, 2.88(kg-BOD/kg-MLVSS day)의 고농도 폐수를 유입하여도 슬러지의 팽화현상없이 SVI(sludge volume index)를 150 이하로 유지하였다. 이것은 최대 허용부하를 일반적인 활성슬러지법에 비하여 7.2배 높일 수 있는 효율적인 방법으로 평가되었다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.85-88
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• 2003

Polycyclic aromatic hydrocarbons (PARs) are an important group of organic contaminants present in sewage sludge, due to their persistence, toxic, bioaccumulative and long range transfer. These characters make themselves as Persistent Organic Pollutants(POPs) in Long Range Transboundary Air Pollutions convention(LRT AP) of Europe. A method of the gas chromatographic-mass spectrometric (GC-MS) determination of PARs present in sewage sludge was developed and applied to analyzed samples from five sewerage treatment plants (SWTPs), having different treatment types. PARs were extracted from freeze-dried samples by toluene 16 hours in a soxhlet extraction system. The sludge extracts were cleaned-up by an activated silica gel column chromatography. The sum of the 16 US Environmental Protection Agency PARs sewage sludge samples varied from 2.44 to 4.82 ${\mu}g$/g. Concentration of emission carcinogen PARs(PARcarc), such as Benzo(a)anthracene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Dibenzo(a, h)anthracene and Indeno(1, 2, 3-cd)pyrene ranged from 0.62 to 1.03 ${\mu}g$/g. The total amount of PAHs emission from sewage sludge in Korea was calculated as a top-down approach. PARs and $\sum$PAHcarc from sewage treatment plants had several pathway each by-products. In the ocean dumping, PAHs and $\sum$PAHcarc emissions were 1155.95 kg/year and 5040.32 kg/year. In recycle, PAHs and $\sum$PAHcarc emissions were 98.36 kg/year and 428.87 kg/year. In the landfill, PAHs and $\sum$PAHcarc emissions were 190.40 kg/year and 830.21 kg/year. In the incineration, PAHs and $\sum$PAHcarc emission were 33.10 kg/year and 830.21 kg/year. (In case of incineration, the whole provisions of PARs and $\sum$PAHcarc contained to flowed in sludge was supposed to be exhausted to environment through exhaust after incineration.)

• 한국지반환경공학회 논문집
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• 제16권5호
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• pp.27-33
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• 2015

정수공정 중에 응집된 망간은 슬러지 농축조에 체류하는 동안 재용출 되어 배출수의 망간 허용기준치를 초과하는 문제가 발생되고 있다. 본 연구에서는 정수공정 중에 슬러지 농축조 배출수의 pH를 조정함으로써 망간 농도에 미치는 pH의 영향에 대하여 연구하였다. 초기 pH 6.1에서는 응집된 슬러지로부터 망간이 재용출 되어 청정지역 배출 기준인 2mg/L를 초과하였으나 NaOH, KOH, CaO, $Ca(OH)_2$, $CaCO_3$ 등 알칼리 물질을 이용하여 pH를 상승시켰을 경우 망간 농도를 청정지역 배출 기준 이하로 낮출 수 있었다. 또한 알칼리성 물질로서 석회석 광산에서 선별과정 중 발생하는 폐석회석을 이용하여 정수장 슬러지의 망간 재용출을 억제할 수 있는 가능성을 확인하였다.

• 상하수도학회지
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• 제10권2호
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• pp.104-116
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• 1996

Anaerobic digestion is generally used for the treatment of volatile organic solids such as manure and sludge from waste water treatment plants. However, the reaction rate of anaerobic process is slow, and thus it requires a large reactor volume. To minimize such a disadvantage, physical and chemical pre-treatment is generally considered. Another method to reduce the reactor size is to adopt different reactor system other than CSTR. In this paper, the effects of heat pre-treatment and reactor configurations on the anaerobic treatability of volatile solids was studied. Carrot, kale, primary sludge, and waste activated sludge was chosen as the test materials, and the BMP method was used to evaluate the maximum methane production and first order rate constants from each sample. After the heat treatment at $130^{\circ}C$ for 30min., the measured increase in SCOD per gram VS was up to 394 mg/L for the waste activated sludge. However, the methane production potential per gram VS was increased for only primary and waste activated sludge by 17-23%, remaining the same for carrot and kale. The overall methane production process for the tested solids can be described by first order reactions. The increased in reaction constant after heat pre-treatment was also more significant for the primary and waste activated sludge than that for carrot and kale. therefore, the heat pre-treatment appeared to be effective for the solids with high protein contents rather than for the solids with high carbohydrate contents. Among the four reactor systems studied, CSTR, PFR, CSTR followed by PFR, and PFR with recycle, CSTR followed by PFR appeared to be the best choice considering methane conversion rate and the operational stability.

• 환경위생공학
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• 제8권1호
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• pp.117-127
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• 1993

When incineration method is utilized as a disposal process of sludge, the treatment generally consists of thickening, dewatering and incineration, implying that sludge dewaterability has a colose relationship with operating condition of a thickener. Dewatering factors should be, therefore investigated for achieving effective sludge treatment. No research on this has been performed in Korea. This study has focused on the evaluation on the effects of thickener operating variables on sludge dewatering, including sludge feed types and retention time. Mixing ratio of the first and the second sludge and operation time were varied in order to observe the change of dewaterability and optimum input of chemical conditioner.

• 한국농공학회지
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• 제40권2호
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• pp.102-111
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• 1998

Large amount of sludge have been generating in the process of water and wastewater treatment in urban area, and it has been making many environmental problems. Currently almost of sludge is landfilled, and since sludge is difficult to handle and dehydrate, the permeated water from the filled-in ground contaminate the surrounding soil and groundwater which may cause serious environmental and sociological problems. The organic component in sludge can be almost removed through the heat treatment process, and the final product is called artificial soil or artificial media according to the temperature control. To produce artificial media using sludge, chabazite and lime were used as an additive, and the mixture of sludge & additives was thermally treated in the firing kiln at about 800~1, 100。C for about fifteen minutes. The physical and chemical characteristics of the produced artificial media were analyzed, and it showed that it can be used as an artificial media for plant production or soil conditioner for farmland. The concentrations of the toxic heavy metals in the artificial media were lower than the soil quality standard for farmland. The characteristics of produced artificial media, using the mixture of sludge and additives through the heat treatment, is similar to the natural chabazite and soil. The analyzed result of the mineral composition of artificial media showed that it has a characteristics similar to natural stable soil, so the produced artificial media may be applied to farmland or water culture without causing adverse effect. Therefore this study showed that the above process can be a feasible alternative for sludge treatment.

• 환경위생공학
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• 제13권1호
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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.

• 상하수도학회지
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• 제11권1호
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• pp.64-73
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• 1997

Most of the municipal wastewater treatment plants operated in Korea are designed for high concentrations municipal sewage. However, activated sludge process employed by municipal wastewater treatment plant is operated at low organic loading. The objective of this study was to determine optimum operating condition of activated sludge process for treatment of low concentration municipal sewage. Three bench scale activated sludge reactors were operated to investigate the effect of HRT and SRT on the COD and TSS removal efficiency. The average concentration of TSS, SCOD, SBOD and TKN in influent were 118mg/l, 61mg/l, 21mg/l, and 12mg/l, respectively. The activated sludge reactors operated with various HRT and SRT showed about 89-93% TSS removal efficiency. HRT and SRT does not affect the TSS removal efficiency of actvatied sludge process significantly. However, HRT affected the SCOD removal efficiency slightly. As the HRT decreases from 13hours to 3hours, the SCOD removal efficiency decreases from 67% to 56%. The average effluent TCOD concentration of the reactor operated with 3hours of HRT was approximatly 40-45mg/l. Kinetic coefficient yield (Yt) and decay coefficients(Kd) were 0.594-0.954 mgMLVSS/mgCOD and $0.0197-0.0317day^{-1}$, respectively. Low concentration municipal sewage can be treated with 3 hours of HRT without effluent quality deterioration and SRT does not affect the substrate removal efficiency at this operation condition.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.182-186
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• 2001

An acid forest surface soil as a land farming medium was treated with a water plant alum sludge at 0 to 18%. Indian mustard was grown in the treated soil in a greenhouse for 5 weeks and watered with pH 4 tap water adjusted with a mixed acid (1HNO$_3$: 2H$_2$SO$_4$) during plant growth. Changes in soil property, leachate chemistry, plant growth, and plant uptake of elements by the sludge treatment were determined. The alum sludge treatment increased buffer capacity to acidity, hydraulic conductivity, water holding capacity, and phosphate adsorption of the soil and decreased bulk density and mobility of small particles. The sludge treatment reduced leaching of Al, Mg, K, Na, and root elongation. Plant did uptake less amount of the cations and P but more Ca with the sludge treatment.

• 한국물환경학회지
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• 제20권4호
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• pp.346-351
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• 2004

Because of being produced a great deal of excess sludges from biological wastewater treatment process, the subject regarding treatment and disposal of them has been significantly handled in real plants. It should be considered the alternative treatment with easy operating and cost effective process in rural areas. For the thickening of wasted activated sludge from small scale wastewater treatment facilities, thus, the provisional sludge thickening system was developed by the application of mesh filter module. Three meshes with different pore size(100, 150, $200{\mu}m$) were prepared for filter modules that were used to withdraw effluent from thickening system. A filter module with $100{\mu}m$ mesh was chosen as the most effective thickening material in the viewpoint of volume reduction and effluent quality: the volume reductions of initially injected sludge with 3,600 mg/L and 9,100 mg/L were 95% and 85%, respectively, and the filtered effluents were enough good to be shown below 1.0 mg/L of SS and 1.0 NTU of turbidity. Since the filtration of thickening was influenced by the cake layer formed on mesh filter module and this system was operated in the combination of sludge thickening with gravity settling, the filter modules with smaller pore size and the larger floc size were required for long term operation safely.