• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.239-244
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• 2004

The purposes of this study were to examine applicability of limestone as a conditioning agent and to determine the optimum conditions for improving dewaterability of digested sludge. The optimum conditions for temp., pH, dosage, particle size, time, and pressure was $30^{\circ}C$, 7, 45 g/l, 100 mesh, 30 min., and $2.66 {\times} 10^4 N/m^2$, respectively. On the basis of induced optimum conditions, if adding limestone in digested sludge, it estimated that its specific resistance was $1.43 {\times} 1012 m/kg$. Therefore, it seemed that we could utilize limestone as conditioning agent for improving dewaterability of digested sludge.

• 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 Water and Wastewater
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• v.21 no.1
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• pp.123-130
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• 2007

The effects of hydrogen peroxide treatment on the reduction of waterworks sludge were investigated in this study. Sludge treated by peroxidation $H_2O_2$ oxidation) was dewatered using a pressure filter at 3atm. It was observed that $H_2O_2$ treatment at the acidic condition significantly reduce both cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability by hydrogen peroxide treatment at pH 3.5 was better than acidic treatment and became comparable with polymer conditioning. The sludge filterability evaluated by SRF was optimal at a dose 2ml $H_2O_2$/sludge($0.02g\;H_2O_2/gTS$) after adjusting of pH to 3.5. The $H_2O_2$ oxidation at pH 3.5 also produced even more dewatered cake when compared with polymer conditioning. The reduction rate of sludge mass at an optimal condition showed 34% compared with untreated sludge. The effects of peroxidation on sludge properties including zeta potential, bound water and particle size were also evaluated. Peroxidation at the acidic condition reduced both bound water and zeta potential. By $H_2O_2$ combined with sulfuric acid leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.

• 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 Water and Wastewater
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• v.32 no.2
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• pp.89-96
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• 2018

This study aimed to investigate the feasibility of improving dewaterability and settleability of sewage sludge using coagulation sludge. When mixed with sewage sludge and coagulation sludge at 1:1 ratio, capillary suction time(CST) and specific resistance to filtration(SRF) decreased by about 56% and 68%, respectively. It is found that total solids(TS) and volatile solids(VS) of mixing sludge are increased by about 59% and 53%, respectively. Also, the turbidity of the mixing sludge supernatant was reduced from 99 to 16 NTU. It is observed that the mixing of sewage sludge and coagulation sludge at 1:1 showed better effect than using poly-aluminum chloride(PAC) coagulant at 25 mg/L.

• 수도
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• v.24 no.1 s.82
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• pp.36-40
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• 1997

• Journal of Environmental Science International
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• v.7 no.6
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• pp.867-873
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• 1998

Laboratory study was conducted to provide basic data for operating anaerobic sequencing batch reactor(ASBR) process for treatment of nightsoil. The experiments were concerned with digestion characteristics, settleabiltity and dewaterability of digested sludge in ASBR system. Completely-mixed dally-fed control reactor without solid-liquid separation step was also operated to evaluate the baseline performance since the nature of nightsoil was changed with time. In all case, gas production from the ASBR shows 1.3 to 1.44 times higher than that from control, in spite of almost similar trend in organics removal. During thickening period, remarkable decrease in surface settling velocity was observed at the ASBRs compared with the control. In case of the ASBR run, flotation of mixed digested sludge was not occurred. Also, ultimate thickened volume of ASBRs increased 1.2~1.5 times compared with control. Dewaterability of digested sludge without conditioning decreased when the completely-mixed daily-fed reactor for ASBR run was converted to the ASBR. However, improvement of dewaterability of digested sludge from the ASBRs was observed as a result of addition of FeCl$_3$ to digested sludge for conditioning.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1326-1331
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• 2009

Drying process in the cylindrical thin film layer of sludge with the thickness less than a few millimeters has been investigated. Thin film drying is specially designed and used to dry the viscous materials like sewage sludge. The thin film layer of sludge is dried on the metallic cylindrical surface through which thermal energy is supplied to the layer during drying. The wall temperature is assumed to be constant during drying in the present study for the simplification. In order to solve the equations, the mass transfer rate on the drying surface should be determined. The mass flux of evaporated water vapor on the surface is estimated with the formulation given in the literature. The effect of some physical parameters on drying has been examined to figure out the drying characteristics of the sludge layer.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1128-1133
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• 2008

Drying process in the thin film layer of sludge with the thickness less than a few millimeters has been investigated using the simple one-dimensional model. Thin film drying is usually used to dry the viscous materials like sewage sludge. The thin film layer of sludge is dried on the metallic surface through which thermal energy is supplied to the layer during drying. In order to solve the equations, the mass transfer rate on the drying surface should be determined. The mass flux of evaporated water vapor on the surface is estimated with the formulation given in the literature. The effect of heating temperature, film thickness, and air velocity on drying has been examined to figure out the drying characteristics of the sludge layer.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.17-21
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• 2001

The object of this study is to find out the characteristics of waste oyster shells and determine the proper dosage of powdered waster oyster shells as the conditioning agent for water treatment sludge dewatering process. The large amount of waste oyster shells which discharges from the oyster farming, occurs serious environmental hazards. However, oysters shell contain large amount(about 38% by weight) of alkaline minerals, such as calcium and magnesium and so on, this natural material is thought to have the petential ability as a good conditioning agent. The results of this study are as follows. The optimum condition for improvement of the water treatment sludge dewaterability is when 6 g of waste oyster shell powder added to 200$m\ell$ of water treatment sludge. At optimum condition, the solid contents can reach to 31.78% and the specific resistance of conditioned sludge is 0.16$\times$10$^{8}$ sec$^2$/g. However, exceeding the of powdered waste oyster shell is needed to get the effective result. Consequently, the waste oyster shell can be a recyclable material to improve the dewaterability of water treatment sludges.