Effect of ultrasonic waves on the rheological features of secondary sludge

Ruiz-Hernando, Maria; Labanda, Jordi; Llorens, Joan

doi:10.1016/j.bej.2010.07.012

Cited by 36 publications

(22 citation statements)

References 44 publications

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“…In addition, the application of pretreatment technologies can modify the sludge rheology. Ruiz-Hernando et al (2010) used ultrasonic waves to pretreat secondary sludge. Both steady state viscosity and thixotropy significantly decreased with specific energy.…”

Section: Introductionmentioning

confidence: 99%

Rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H2O2 pretreatment

et al. 2016

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a b s t r a c tThe rheological behavior of sludge is of serious concern in anaerobic digestion. This study investigated the rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H 2 O 2 pretreatment (MW-H 2 O 2 ). The results showed that MW-H 2 O 2 pretreatment resulted in the improvement of sludge flowability and weakening of its viscoelastic properties. Further positive effects on the rheological properties of digested sludge during anaerobic digestion were observed. The flowability was improved with a low level of apparent viscosity. The decrease of the consistency index and increase of the flow behavior index indicated that the strength of the inner structures and non-Newtonian flow characteristics of digested sludge weakened. Both the storage modulus (G 0 ) and loss modulus (G 00 ) decreased, indicating that the viscoelastic behavior became weak. These effects were possibly attributed to the changes of the digested sludge micro-structures, such as extracellular polymeric substances (EPS). This study concluded that anaerobic digestion for treating sewage sludge combined with pretreatment is a more favorable option than single anaerobic digestion from the perspective of rheology.

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Section: Introductionmentioning

confidence: 99%

Rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H2O2 pretreatment

et al. 2016

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“…The ultrasonic apparatus used was HD2070 Sonopuls Ultrasonic Homogenizer equipped with a MS 73 titanium microtip probe and working with an operating frequency of 20 kHz and a maximum supplied power of 70 W. The specifications of the treatment were the same as those detailed in the previous study [15]. The ultrasonic waves were applied at constant ultrasonication power and different application times to provide specific energies from 3,000 to 33,000 kJ/kg TS.…”

Section: Treatments Conditionsmentioning

confidence: 99%

“…The rheological behavior of sludge under flow conditions was analyzed by two tests, following the procedures described by Ruiz-Hernando et al [15]: hysteresis loop test and shear rate step test.…”

Section: 3mentioning

confidence: 99%

“…In a previous paper it was highlighted the importance of the proper knowledge of rheology to control sludge treatment processes such as dewatering and stabilization [15]. Rheology describes the deformation of a flow under the influence of mechanical stress: viscosity, which determines the thickness of the sludge, is the basic rheological parameter.…”

Section: Introductionmentioning

confidence: 99%

“…In this way, the disintegration produced by ultrasonication is due to two phenomena: hydro-shear strength and sonochemical effects. Thus, ultrasonication would enhance the solubilization of organic matter, decrease sludge viscosity and increase sludge homogeneity [14][15].…”

Section: Introductionmentioning

confidence: 99%

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Dewaterability of sewage sludge by ultrasonic, thermal and chemical treatments

Ruiz-Hernando

Martinez-Elorza

Labanda

et al. 2013

Chemical Engineering Journal

Self Cite

141

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Sludges resulting from wastewater treatment processes have a characteristically high water content, which complicates handling operations such as pumping, transport and disposal. To enhance the dewatering of secondary sludge, the effect of ultrasound waves, thermal treatment and chemical conditioning with NaOH have been studied. Two features of treated sludges were examined: their rheological behavior and their dewaterability. The rheological tests consisted of recording shear stress when the shear rate increases and decreases continuously and linearly with time, and when it increases and decreases in steps. Steady-state viscosity and thixotropy were obtained from the rheological tests, and both decreased significantly in all cases with increased treatment intensity. Centrifugation of ultrasonicated and thermally treated sludges allowed the total solid content to be increased by approximately 16.2% and 17.6%, respectively. These dewatered sludges had a lower viscosity and thixotropy than the untreated sludge. In contrast, alkali conditioning barely allowed the sludge to be dewatered by centrifugation, despite decreasing its viscosity and thixotropy.

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Methodology for technical and economic assessment of advanced routes for sludge processing and disposal

Bertanza

Canato

Laera

et al. 2014

Environ Sci Pollut Res

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In order to meet the environmental legislative framework in force in Europe and reduce sludge processing and disposal costs, several sludge treatment technologies and management strategies have been proposed in the last two decades. The evaluation of their technical and economic suitability, case by case, may be a challenge, since many aspects are involved, so that a robust decision support system should be used. Within the ROUTES project (founded within the EU Seventh Framework Programme), the authors have developed an assessment procedure which allows rating several technical factors (such as system reliability, complexity, safety aspects, modularity, etc.) and estimating capital and operating costs, in case a plant is being upgraded. The comparison between the original (reference) plant and the modified configuration informs about technical hot spots (which are expressed by a traffic light-type colour code) and cost gaps resulting from the implementation of the new solution.

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Effect of ultrasonic waves on the rheological features of secondary sludge

Cited by 36 publications

References 44 publications

Rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H2O2 pretreatment

Rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H2O2 pretreatment

Dewaterability of sewage sludge by ultrasonic, thermal and chemical treatments

Methodology for technical and economic assessment of advanced routes for sludge processing and disposal

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