• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.743-748
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• 2009

Chemical sludge conditioning is widely used to improve the dewatering efficiency. It is treated with commonly used conditioners, and then thickened and dewatered with a mechanical device. This paper aims to examine the flotation and thickening efficiencies of sewage sludge for conditioning conditions, such as unaerobic storage time, kinds of coagulant and dosages, and flotation conditions, such as sludge concentration and A/S ratio, using an dissolved air flotation apparatus. Experimental results showed that the specific surface area and specific resistance to filtration (SRF) were significantly increased and the flotation and thickening efficiencies were decreased with anaerobic storage time. However, the flotation and thickening efficiencies faintly decreased in sewage sludges conditioned as $Al_2(SO_4)_3$, $Fe_2(SO_4)_3$, and PSO-M. Flotation and thickening efficiencies in conditioned sewage sludge could be sustained up to 96% at A/S ratio of 0.01 mL/mg or over.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.93-100
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• 2005

Comparative thickening and dewatering characteristics of municipal wastewater sludge were investigated in terms of separated and combined treatment of primary and secondary BNR sludge. Also, various conditioning methods such as cation polymer addition, steam and ultrasonication treatment were examined to improve dewaterability of sludge. The dewaterability was measured by using specific resistant test, wedge zone simulator and centrifuge. The result of the sludge thickening test revealed that separated thickening was better in terms of solids recovery and supernatant quality. Particularly, the thickening of primary sludge with high solids (about 3.5% TS) showed very poor solid separation. The addition of cation polymer showed better conditioning characteristic for dewatering and the optimal polymer dosage was 0.26% for primary sludge, 0.43% for secondary sludge and 0.38% for combined sludge. Contrary to the result of the thickening, the dewatering test revealed that dewatering of the combined sludge is better than that of separated sludge, representing better solids separation and filtrate quality. The polymer addition was essential to improve dewaterability in filter (belt) press type dewatering but it was inefficient for the dewatering of secondary sludge only. The centrifuge type dewatering showed better performance and the dewaterability was slightly improved when the polymer was added. Based on the results of this research a sustainable sludge treatment process, particularly in terms of the recycle water quality and solids recovery, was proposed.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.10
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• pp.651-655
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• 2012

This study aimed to investigate the effect of an inorganic conditioner composed of natural inorganic materials on the dewaterbility of sewage sludge and compare the performance with those of conventional organic polymeric conditioners. A dosage of 2.0 mg inorganic conditioner/g sludge TS decreased time to filter test (TTF), specific resistance to filtration (SRF), water content of dewatered sludge cake, turbidity from 146 to 41 sec, from $8.3{\times}10^{14}$ to $2.4{\times}10^{14}$ m/kg, from 82.1 to 77.1%, from 112 to 61.1 NTU, respectively, which was compatible to the conventional cation organic polymer. An inorganic conditioner would be used in sewage sludge treatment as a suitable alternative conditioner. Regression analysis showed a strong relationship among TTF, SRF, and water content.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.2
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• pp.125-131
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• 2002

This study was carried out to evaluated for dewaterability of sewage sludge using waste oystershell and loess. The Jar-Test and the Buchner funnel test were proceeded for the assessment of dewaterability of a thickened sludge and digested sludge. TTF(Time to Filter), SRF(Specific Resistance to Filtration) were adopted as the valuation indices of sludge dewaterability. Dewatering conditioner which composed of both oystershell and loess is much dewaterable than the one composed of only oystershell. In the course of combining with oystershell and loess, the following fact was found that the dewaterability of the combination which have the higher ratio of oystershell than that of loess is superior. The most suitable oystershell :loess ratio of dewatering conditioner is 9:1 in treating both thickened sludge and digested sludge.

• Resources Recycling
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• v.13 no.3
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• pp.12-18
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• 2004

A study on the enhancement of the dewaterability of sewage sludge was carried out by using the sea waste materials as a dewatering aid. It was made from a starfish and a shell by heating at $105∼700 ^{\circ}C$ and centrifuge and belt press were used as a mechanical dewatering process. The moisture content of sludge cake was reduced by 15∼22% (w/w) after addition of the dewatering aid at the dose of 1∼8 g/100mL of digested sludge. CST (capillary suction time) was measured to evaluate the effect of dewatering aid on sludge dewatering properties. CST was reduced after addition of a shell while increased after addition of a starfish. Enhancement of dewaterability after addition of a shell was better than that of a starfish. The heating temperature effect of the dewatering aid on dewaterability was not clear.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.641-648
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• 2009

The study presents sewage sludge flotation and thickening efficiencies which changes chemical conditioning and mixing conditions using a flotation thickening system with a microbubble generating pump. Flotation and thickening of sewage sludge are shown to significantly influence kinds of coagulants more than Gt values. It is found that the flotation and thickening efficiencies for kinds of coagulants follows the order: $Al_2(SO_4)_3$ < PSO-M < $Fe_2(SO_4)_3$. We shows that the flotation thickening system(1.6 $m^3$/d) could be continuously operated during two hours on operation conditions in the lab-scale experiments. Sludge thickening efficiency in the A/S ratio of 0.029 - 0.019 mL/mg was found to be very efficient, reaching to 300.0~335.7%.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.775-780
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• 2008

Sludge conditioning is widely used to improve aggregation and dewaterability of waste sludge in sludge treatment processes. The study aims to examine quantitative correlations between coagulant dosage and sludge cake dewaterability using three kinds of coagulants, such as an aluminum sulfate, a ferric chloride, and a poly aluminum chloride(PAC). When an aluminum sulfate, a ferric chloride, and a PAC were injected with 0.79$\sim$1.19 mmol/g, 0.61$\sim$1.25 mmol/g TSS, and 0.21$\sim$0.39 mmol/g TSS, respectively, specific resistances to filtration of the sludge were decreased at 95.0% or more. This study shows that the correlation between coagulant dosage per g sludge(D) and normalized specific resistance to filtration(R) could be expressed by the exponential functions.

• Journal of Bio-Environment Control
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• v.12 no.4
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• pp.245-251
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• 2003

This study was cnducted ton investigate the effect of soil conditioner such as dolomite, slkudge and organic manure on changes of soil chemical properties of abandoned zinc mine area. Growth responses of Chrysanthemum azwadskii and Caryopteris incana (Tunb) Miq affected by the appication were also determined. In thejsoil of abandoned zinz mine area, total heavy metal contents espectially Cd, Cu, Pb and Zn were high and organic matter contents was low. Application of sludge for phytoremediation resulted in higher soil organic content that other treatments tested. Heavy metal concentrations after application of soil conditioners were not different among treatments. The growth of C. zawadskii and C. incana (Tunb) Miq were significantly higher in sludge treatment than those in other treatments The cholrophyll content, chlorophyll flouorescence, protein content, photosynthetic rate and transpiration were high in sludge treatment. The heavy metal contents of C. zawadskii were the lowest in sludge treatment while those of C. incana (Tunb) Miq was the highest in sludge treatment.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.401-401
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• 2022

우리나라 대규모 하수처리장에 상용화되어있는 응집공정의 운영상 난점을 극복하고자 대체공정으로 고안된 인 결정여과공정(HCF, Hydroxyapatite Crystallization-Filtration process)의 pilot plant를 구축하고 부산슬러지의 자원화를 위해 그 특성을 검토하였다. 기존의 hydroxyapatite(HAP) 결정화공정 내 탈탄산(decarbonation) 단계를 생략하는 HCF공정의 경우에 고농도의 Ca²⁺ 주입과 처리수내 탄산염으로 인해 HAP을 포함하는 석회계 슬러지가 발생하는데, 이는 산성화된 토양의 개량제(중화제)로 널리 사용될 수 있다. 본 연구를 위해 경기도 I하수처리장 2차침전지 후단에 구축된 처리용량 27.1 - 135.6 m³/day HCF pilot plant의 전처리 조건은 pH 10.0 - 11.0, Ca²⁺ 농도 80 mg/L이었다. 결정여과조는 선속도 1.0 - 5.0 m/hr, 상향류로 운전되며, 여재는 2.0 - 3.0 mm의 석회석 모래를 충전하였다. 역세척은 중앙에 Air lifting pipe를 설치하여 역세척수가 처리수와 분리배출되도록 설계하였고, 침전시켜 역세척 슬러지를 회수하였다. 처리수의 평균 T-P, PO₄-P 및 SS는 각각 0.05, 0.04, 1.1 mg/L으로 모든 항목에서 방류수 수질기준 이하로 안정적으로 유출되었다. 회수된 HCF 슬러지는 SEM-EDX, XRD, FT-IR을 활용하여 그 특성을 분석하였다. SEM-EDX로 분석된 슬러지의 원자분율은 CaCO₃ 또는 HAP으로 추측되었다. 또한, XRD spectrum 분석결과, 슬러지의 주요 구성성분은 calcite, HAP, phosphoric acid(H₃PO₄) 및 brusite로 나타났다. FT-IR 분석결과, 슬러지는 대부분 인산염 및 탄산염의 무기물로 구성되어 있으며, 유입수의 인 농도가 높을수록 슬러지 내 HAP의 함량이 calcite보다 높은 것으로 나타났다. 고농도의 Ca²⁺을 주입하여 탈탄산단계를 생략한 HCF의 부산슬러지는 HAP 이외에도 CaCO₃와 칼슘-인 화합물로 구성되어 있는 것으로 나타났다. 하수 인 고도처리를 위한 HCF공정의 하수처리시설 인 고도처리 적용이 검증되었으며, 부산슬러지를 산성화된 토양의 개량제(중화제) 또는 비료로서의 재활용 및 자원화 가능성이 시사되었다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.732-738
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• 2005

The purpose of this study is the presentation of the proper microwave treatment conditions by means of the investigation of the effect of microwave irradiation on the dewaterability and dryability of sludge. For the improving of dewatering efficiency of sludge using the microwave, the proper time of microwave irradiation is very important. The dewatering efficiency of thickening sludge conditioned by microwave irradiation for proper time was considerably improved with reducing of capillary suction time from 52.3 sec to 30.8 sec, and the sludge conditioned by microwave irradiation had contained the moisture of 81.4% after that pressure filtrationed. The result of drying characteristics of dewatered sludge using the microwave irradiation and furnace heating, for drying of sludge to moisture of below 55%, microwave irradiation time was required 3 min, whereas, furnace heating was required 40 min at $105^{\circ}C$, 20 min at $170^{\circ}C$ and 9 min at $300^{\circ}C$, respectively. We certified that the drying of dewatered sludge using the microwave irradiation was effectively reduction of moisture of sludge compare to traditional heating method.