Abstract

Controlling the residence time in paddle dryers and the drying efficiency imply the knowledge of rheological behaviour of highly concentrated and pasty sludge and its temperature dependency. However, because of perturbing effects such as evaporation, measurements are not fully representative of intrinsic sludge properties. Classical techniques usually considered in the literature for evaporation control are not efficient at high temperatures. This work gives a method to control the evaporation at high temperature that can be used with any commercial rheometer. The configuration concept is to prevent water loss by limiting the contact between the sheared sludge and the environment. This configuration allows preventing evaporation up to 80 °C at least during 2 h. Its efficiency is confirmed at different total solid (TS) contents ranging from 20 to 47 wt.%.

INTRODUCTION

In the EU, sludge production is increasing every year and is becoming a real challenge for the waste water treatment plants (WWTP) (Fytili & Zabaniotou 2008; Eshtiaghi et al. 2013; European Commission 2017). Thermal drying is one of the most commonly used operations to reduce volumes but part of the energy is unnecessarily consumed due to not optimised process (Chabrier 2007; Arlabosse et al. 2012; Charlou et al. 2015; Milhé et al. 2015). The dryer energy consumption can be optimised by an accurate control of the operating parameters, among which the residence time distribution which is directly linked to the flow rates in the dryer (Djerroud 2010; Arlabosse et al. 2012; Charlou et al. 2015). Controlling the residence time distribution implies the knowledge of the main rheological parameters of sludge especially for total solid (TS) contents higher than 20 wt.% and their temperature dependency-during drying.

However, rheological measurements are hard to perform at high TS as perturbing effects appear such as fractures and evaporation (Baudez & Coussot 2001; Chaari et al. 2003; Charlou 2014). Indeed, at high TS, the interactions between particles are mainly frictional leading to fractures during shear, inducing bad rheological data. In a previous work, it has been shown how to correct fracture impact at ambient temperature with a well-controlled procedure allowing the exact determination of the surface really sheared and, thus, of intrinsic rheological parameters (Mouzaoui et al. 2018).

During a long duration or high temperature tests, additional problems occur such as water loss and sample drying. Consequently, the measured rheological data are not fully representative of a controlled state of the sludge. To overcome this problem and minimize measurement errors, the most frequently used solutions in rotational rheometers (with plane-plane, coaxial-planar and coaxial-plane geometries) consist in applying a Newtonian oil film around the free surfaces of sludge. With such a technique, measurements have been done at temperatures up to 80 °C for diluted sludge, that is TS < 5 wt.% (Ortiz et al. 1994; Briscoe et al. 1998; Baudez et al. 2013b) but only up to 60 °C at higher concentrations, that is TS up to 16 wt.% (Baudez et al. 2013a; Jiang et al. 2014; Ségalen 2015). This observation is due to the fact that rheological properties are more sensitive to water evaporation at high TS. However, the applicability of this method is limited at low experiment duration (lower than 20 min) and is not adapted to pasty sludge, since fractures appear under shear measurements, leading to sample drainage and undesirable mass transport between the sludge and the surrounding oil layer.

The literature has underlined another solution to control the evaporation during rheological measurements consisting of keeping a saturated atmosphere during experimental tests. Attachments/additional pieces to minimize the evaporation effects have developed in that perspective. For instance, consisting of an insulated sample chamber (cover) and a vapour trap (Gans et al. 1999; Nommensen et al. 1999; Ksapabutr et al. 2004). This method has been implemented in several works, as for clay-polymer mixtures at ambient temperature (Benchabane 2006; Ebagninin 2009), diluted carboxymethyl cellulose (CMC) solutions (<5 wt.%) at temperatures up to 80 °C (Benslimane 2012) or pasty sludge with TS content up to 28.5 wt.% at temperatures up to 60 °C (Dieudé-Fauvel et al. 2009; Hammadi et al. 2013; Feng et al. 2014). Later, to keep a saturated atmosphere, Quignon-Tosoni (2015) has used an apparatus adapted from a nebulizer to the geometry of the rheometer (coaxial cylinders) and observed no change in the viscosity of clay suspensions for 24 h at room temperature. However, a gradual evolution in sample viscosity due to evaporation was highlighted even at 40 °C by Sato & Breedveld (2005), leading to unrealistic rheological properties. Keeping a saturated atmosphere thus seems an efficient technique to prevent water evaporation in the case of pasty materials, but it seems to be adapted to temperatures lower than the ones used in thermal drying, typically from 90 to 120 °C.

Several authors have shown that the solubilisation of organic matter (from the solid phase to the liquid phase) at high temperature irreversibly modifies the structure of the sludge and therefore its rheology (Pevere et al. 2009; Appels et al. 2010; Farno et al. 2015, 2014). The time and the temperature of thermal treatment are the dominant factor influencing the organic solubilisation and thus the rheological parameters. Indeed, the organic matter solubilisation during thermal treatment could reach a stable state within 30–60 min with respect to temperatures higher than 100 °C (Carrère et al. 2010; Zhang et al. 2017) but ranged from hours to days at temperatures lower than 100 °C (Climent et al. 2007; Xue et al. 2015).

Finally, the literature highlights a lack of techniques adapted to control the evaporation of water at high temperature during rheological measurements, especially for on highly concentrated suspensions such as pasty sludges. This paper aims to fill this gap by proposing a specific procedure to prevent the water evaporation at high temperatures during rheological measurements on pasty sludge. This allows to obtain intrinsic rheological parameters and thus a better understanding of pasty sludge behaviour in the dryer. The efficiency of this technique at high temperatures is first validated on sludge having 20 wt.% TS, then confirmed at 28 and 47 wt.% TS.

MATERIAL AND METHODS

Sludge

Pasty sludge was sampled at the WWTP from Albi city (France) at the outlet of the centrifuge. It is produced from extendedly aerated, thickened and digested municipal wastewater. Its initial TS (standard EN 12880:2000) was 20 wt.% and the volatile solid (VS, standard EN 12879:2000) content was about 63 wt.% (of dry weight). Samples with higher TS contents have been prepared in a filtration/compression cell inserted in a hydraulic press (Carver, USA). A sludge mass of 0.8 kg is pressed for 48 and 72 h at a pressure of 30 bar. The temperature of the laboratory is maintained at 20 °C.

To avoid the problem of solubilisation during rheological tests, samples were thermally pre-treated at 90 °C during 24 (in a hermitic container) prior to measurements. The TS and VS contents have been determined before and after the thermal treatment to check that this treatment did not alter the sludge. Table 1 shows the result for the initial sludge.

Table 1

Measurement of TS and VS contents before and after the thermal treatment

 Before thermal treatment After thermal treatment 
TS content (wt.%) 20.3 20.4 
VS content (wt.% TS) 63.2 63.1 
 Before thermal treatment After thermal treatment 
TS content (wt.%) 20.3 20.4 
VS content (wt.% TS) 63.2 63.1 

Rheological measurements

Rheological measurements are performed with a stress-controlled rheometer (HAAKE RheoStress 600, Thermo Scientific, Germany). The upper part supplies measurements, while the lower part is fixed. Two configurations described thereafter are implemented: plate-plate and plate-cylinder configurations.

A constant dynamic strain (γ = 0.3%) in the linear viscoelastic range (LVE) is applied. Viscous modulus G’, elastic modulus G’ and loss tangent Tan δ (viscous to elastic modulus ratio) are recorded over 3 h. This helps at evaluating the evaporation kinetics of sludge, and hence, at defining the appropriate conditions to prevent evaporation.

The TS contents of sludge is measured prior and at the end of each test. For the plate-plate configuration, the whole sample between the measuring tools is extracted while, for the plate-cylinder configuration, only part of the sample below the upper plate is extracted.

Plate-plate configuration

The geometry consists of a classic serrated plate-plate with a 35 mm diameter (Figure 1). The gap is kept constant at 2 mm. A Peltier temperature controller is connected to the lower plate. To prevent evaporation, measurements were carried out in a vapour saturated medium by using a cover and a vapour trap (Figure 1). The cover (made of Teflon) and the vapour trap (made of steel) are manufactured by Thermo Scientific. The vapour trap is connected to the shaft of the upper plate. Its principal role is to provide a tight seal between the shaft and the cover. A ring is mounted directly onto the cover: when the cover is placed, the ring lowers into the water in the vapour trap. The water on the lower plate is used to saturate air trapped in the chamber (under the cover). It can contain up to 2 mL of water which is sufficient to saturate the air even at 80 °C. For example, based on humid air material balance calculi, the quantity of water needed to saturate the chamber at 80 °C is close to 0.5 mL. Thereafter, only experiments without the vapour trap will be notified (no protection).

Figure 1

Plate-plate configuration used to prevent evaporation.

Figure 1

Plate-plate configuration used to prevent evaporation.

Plate-cylinder configuration

The geometry consists in a serrated upper plate (35 mm diameter) coupled with a lower cylinder (36.88 mm inner diameter and 50 mm depth; see Figure 2). A temperature-regulated bath is connected to the lower cylinder. The sludge sample (at a constant volume for each experiment) is introduced into the measuring cylinder (Figure 2(a)). Then the upper plate is moved down in the sample so as to form a sludge ring around the upper plate of height h = 1.5 mm (Figure 2(b)). This step aims at limiting the contact between the sheared sludge and the environment. The upper plate is turned around = 2 rad (Figure 2(b)) to eliminate residual stresses generated by the surrounding sludge ring. Because of the latter step, the sample may not adhere correctly to the lower surface of the upper plate. To ensure this contact, the upper plate is lowered again by 0.5 mm: the new height of the sludge ring is thus h + 0.5 mm (Figure 2(c)).

Figure 2

Plate-cylinder configuration used to prevent evaporation.

Figure 2

Plate-cylinder configuration used to prevent evaporation.

Finally, to improve the protection against evaporation, measurements are carried out in a vapour saturated medium by using the vapour trap and the cover previously described.

RESULTS AND DISCUSSION

Pre-evaluation tests

Figure 3 presents the evolution of the dimensionless elastic modulus (/ where is the initial value) and the loss tangent (Tan ) as function of time for triplicate using plate-plate configuration at 20 °C on a sludge at TS content of 20 wt.%. The elastic modulus curves present the same shape but with a difference between measurements for times longer than 500 seconds. However, for the same tests, the loss tangent curves are stable and identical during the whole test. All the tests show very good repeatability and reliability. This fact is notably due to the great sensitivity of the elastic modulus to sample preparation but also to the loading of sludge in the measurements device. This is especially true at very low strains as in our case. Therefore, the elastic modulus cannot be used as a reference to track the evolution of water evaporation in this study. The tracking of the loss tangent is thus more relevant to verify whether the water present in the sludge evaporates or not.

Figure 3

Evolution of the dimensionless elastic modulus (a) and the loss tangent (b) as function of time under a constant strain ( = 0.3%) for 20 wt.% TS sludge. is the initial value of the elastic modulus G’.

Figure 3

Evolution of the dimensionless elastic modulus (a) and the loss tangent (b) as function of time under a constant strain ( = 0.3%) for 20 wt.% TS sludge. is the initial value of the elastic modulus G’.

Plate-plate configuration

Table 2 presents the increase in TS content at the end of experiment using the plate-plate configuration for sludge having initially a TS of 20 wt.%. Without protection, the evaporation takes place even at ambient temperature from sludge free surfaces and in contact with an unsaturated atmosphere. This results in a TS increase of 19% after 3 h of experiment at 20 °C and of nearly 100% after only 10 min of experiment at 80 °C. For a 3 h duration at ambient temperature, no change in concentration (negligible increase of 0.2%) is detected in a saturated atmosphere using the cover and the vapour trap. At a higher temperature of 80 °C, because of evaporation, a crusty material is formed on the free edge and as expected, the TS content of the sludge increases by 13% after only 10 min of experiment.

Table 2

TS increase for the plate-plate configuration for 20 wt.% TS sludge

Protection Temperature Time of experiment TS increase (wt.%) 
no 20 °C 3 h 19 
yes 20 °C 3 h 0.2 
yes 80 °C 10 min 13 
Protection Temperature Time of experiment TS increase (wt.%) 
no 20 °C 3 h 19 
yes 20 °C 3 h 0.2 
yes 80 °C 10 min 13 

These results suggest that the combination of cover and vapour trap control the evaporation of water at ambient temperature over long periods of time, but is insufficient to perform measurements at high temperatures.

Figure 4 presents the evolution of the loss tangent as function of time using the plate-plate configuration under different conditions. Without protection at ambient temperature, the tangent loss drops significantly because of the sludge TS increase by 19%. Using the cover and the vapour trap at ambient temperature, the loss tangent decreases until a critical time of about 1,000 seconds, indicating that a restructuration is occurring and the material is becoming more and more elastic (Baudez 2008; Mouzaoui et al. 2018). Then, after 1,000 seconds, the loss tangent tends toward a plateau highlighting a stable behaviour. In fact, sludge is mainly made of water and organic polymers: during shear, there is a strong competition between colloidal forces which tend to rebuild the solid structure (physical aging) and hydrodynamic forces which tend to maintain the broken solid structure. It results in a critical strain below which the solid structure rebuilds even under shear (Baudez 2008). This critical strain is without doubt higher than the strain applied in this study = 0.3%, that is why sludge becomes more elastic. At 80 °C, the formation of the crusty material on the free edge leads to instabilities in the loss tangent throughout the test. It confirms that trapping saturated vapour inside the sample chamber is not sufficient to prevent sample evaporation at high temperature.

Figure 4

Evolution of loss tangent as function of time under a constant strain ( = 0.3%) for 20 wt.% TS sludge.

Figure 4

Evolution of loss tangent as function of time under a constant strain ( = 0.3%) for 20 wt.% TS sludge.

The time-dependency of sludge rheological characteristics makes the estimation of the evaporation kinetic difficult during the first 1,000 seconds. Therefore, to be able to estimate the evaporation kinetic, only the part of measurement where time is higher than 1,000 seconds is considered, i.e. when the sludge behaviour is stable.

Plate-cylinder configuration

Validation test

Data of the plate-cylinder configuration are compared with those obtained using the plate-plate configuration at ambient temperature and in a saturated atmosphere (Figure 5). During the first 1,000 seconds, the sludge behaviour is impacted by the restructuration. Then, beyond 1,000 seconds, all curves become superimposed and almost identical. The important noise previously observed in Figure 4 at 80 °C with plate-plate configuration is weaker.

Figure 5

Evolution of loss tangent as function of time under a constant strain ( = 0.3%) for sludge with 20 wt.% TS.

Figure 5

Evolution of loss tangent as function of time under a constant strain ( = 0.3%) for sludge with 20 wt.% TS.

Results in Table 3 show that TS contents of the sheared sludge is kept constant during at least 3 h confirming an efficient control of the evaporation phenomenon. Moreover, when the measuring tools are removed away, the texture of the sheared sludge looks soft and shiny, while the sludge surrounding the plate (the surrounding ring of sludge) seems hard and crusty, therefore playing the role of a protection layer (Figure 6). Finally, this allows to validate the effectiveness of the plate cylinder configuration to prevent evaporation up to 80 °C.

Table 3

TS contents evolution for the plate cylinder configuration as function of time at 80 °C for 20% TS sludge

Time of experiment TS content (wt.%) 
0 h 20.2 
3 h 20.2 
Time of experiment TS content (wt.%) 
0 h 20.2 
3 h 20.2 
Figure 6

Picture of the sludge after 3 h of experiment at 80 °C for 20 wt.% TS sludge.

Figure 6

Picture of the sludge after 3 h of experiment at 80 °C for 20 wt.% TS sludge.

To evaluate the effectiveness of the plate cylinder configuration at temperatures higher than 80 °C, the experiment was repeated several times at a more elevated temperature that is 90 °C (Figure 7). Large fluctuations in data are highlighted all along the experiment probably due to evaporation. It thus seems not possible to obtain reliable measurements for temperatures higher than 80 °C.

Figure 7

Evolution of loss tangent as function of time under a constant strain ( = 0.3%) at 90 °C using a plate cylinder configuration for 20 wt.% TS sludge.

Figure 7

Evolution of loss tangent as function of time under a constant strain ( = 0.3%) at 90 °C using a plate cylinder configuration for 20 wt.% TS sludge.

Variation of TS contents at 80 °C

As a second practical example, the behaviour of sludge at higher concentrations (28 and 47 wt.% TS) is investigated at 80 °C. Because rheological properties are very sensitive to water evaporation at very high concentration, measurements are performed only for 6,000 seconds (Figure 8).

Figure 8

Loss tangent evolution as function of time under a constant strain ( = 0.3%) at 80 °C for different TS contents.

Figure 8

Loss tangent evolution as function of time under a constant strain ( = 0.3%) at 80 °C for different TS contents.

As expected, during the first 1,000 seconds, the loss tangent signal is dramatically noisy due to inertia and transient conduction. Then, at higher durations, whatever the TS content, curves are identical and tend toward a plateau highlighting a stable behaviour and indicating the absence of evaporation.

This configuration allows to prevent the evaporation whatever the temperature, ranging from 20 to 80 °C, and thus to keep a constant state of the sludge during rheological measurements. The door is now open to define how rheological parameters of pasty sludge evolve with temperature and thus to identify a kinetic function regarding temperature changes during the drying process.

CONCLUSION

The first part of this work demonstrates the difficulties to perform reliable rheological measurements due to the sensitivity of the elastic modulus to sample preparation and loading in the rheometer. However, the loss tangent exhibits very good repeatability and reliability and is thus used as a reference to track the evolution of water evaporation.

The second part shows how evaporation can be controlled in rotational rheometry, by implementing a simple configuration compatible with any commercial rotational rheometer. This configuration consists in an upper plate and a lower cylinder. It is based on the limitation of the contacts between the sheared sludge and the surrounding gaseous environment. It has been shown that this configuration allows preventing evaporation whatever the temperature up to 80 °C for TS contents ranging from 20 to 47 wt.%.

The next step of this work will aim to control both fractures and evaporation at high temperatures in order to obtain realistic rheological parameters of pasty sludges. This leads us to understand how sludge evolves in the dryer and thus to control residence time and drying efficiency.

REFERENCES

REFERENCES
Appels
L.
,
Degrève
J.
,
Bruggen
B. V. d.
,
Impe
J. V.
&
Dewil
R.
2010
Influence of low temperature thermal pre-treatment on sludge solubilisation, heavy metal release and anaerobic digestion
.
Bioresource Technology
101
,
5743
5748
.
Arlabosse
P.
,
Ferrasse
J. H.
,
Lecompte
D.
,
Crine
M.
,
Dumont
Y.
&
Léonard
A.
2012
Efficient sludge thermal processing: from drying to thermal valorisation
. In:
Modern Drying Technology: Energy Savings
.
Wiley-VCH Verlag GmbH & Co.
,
Germany
, pp.
295
329
.
Baudez
J. C.
2008
Physical aging and thixotropy in sludge rheology
.
Applied Rheology
18
,
1
8
.
Baudez
J. C.
,
Slatter
P.
&
Eshtiaghi
N.
2013b
The impact of temperature on the rheological behaviour of anaerobic digested sludge
.
Chemical Engineering Journal
215–216
,
182
187
.
Benchabane
A.
2006
Etude du Comportement Rhéologique de Mélanges Argiles-Polymères : Effets de L'ajout de Polymères
.
Thèse en Mécanique des fluides
,
Université Louis Pasteur Strasbourg, France
.
Benslimane
A.
2012
Rhéologie et écoulement de Fluides Chargés : Application aux Réseaux D'assainissement Urbains. Etude Expérimentale et Modélisation
.
Thèse en Mécanique des fluides
,
Université de Strasbourg, France
.
Briscoe
B.
,
Luckham
P.
&
Zhu
S.
1998
Rheological properties of poly(ethylene oxide) aqueous solutions
.
Journal of Applied Polymer Science
70
,
419
429
.
Carrère
H.
,
Dumas
C.
,
Battimelli
A.
,
Batstone
D. J.
,
Delgenès
J. P.
,
Steyer
J. P.
&
Ferrer
I.
2010
Pretreatment methods to improve sludge anaerobic degradability: a review
.
Journal of Hazardous Materials
183
,
1
15
.
Chaari
F.
,
Racineux
G.
,
Poitou
A.
&
Chaouche
M.
2003
Rheological behavior of sewage sludge and strain-induced dewatering
.
Rheologica Acta
42
,
273
279
.
Chabrier
J. P.
2007
Le séchage thermique des boues: Le développement, ses avantages et ses inconvénients, in: Journée Technique Du SIAAP
.
Charlou
C.
2014
Caractérisation et Modélisation de L’écoulement des Boues Résiduaires Dans un Sécheur à Palettes
.
Thèse en Génie des procédés et de l'Environnement
,
Ecole des Mines d'Albi-Carmaux, Université de Toulouse, France
.
Climent
M.
,
Ferrer
I.
,
Baeza
M. d. M.
,
Artola
A.
,
Vázquez
F.
&
Font
X.
2007
Effects of thermal and mechanical pretreatments of secondary sludge on biogas production under thermophilic conditions
.
Chemical Engineering Journal
133
,
335
342
.
Commission Européenne
2017
Rapport de la Commission au Parlement Européen, au Conseil, au Comité économique et Social Européen et au Comité des Régions
.
Bruxelles, Belgium
.
Dieudé-Fauvel
E.
,
Van Damme
H.
&
Baudez
J. C.
2009
Improving rheological sludge characterization with electrical measurements
.
Chemical Engineering Research and Design
87
,
982
986
.
Djerroud
D.
2010
Modélisation Markovienne du Séchage Continu par Contact Avec Agitation
.
Thèse en Génie des procédés et de l'Environnement
,
Institut National Polytechnique de Toulouse, Université de Toulouse, France
.
Ebagninin
K. W.
2009
Relations Structure Microscopique-Comportement Macroscopique de Suspensions de Bentonite en Présence de Polymères
.
Thèse en Mécanique des fluides
,
Université de Strasbourg, France
.
Eshtiaghi
N.
,
Markis
F.
,
Yap
S. D.
,
Baudez
J. C.
&
Slatter
P.
2013
Rheological characterisation of municipal sludge: a review
.
Water Research
47
,
5493
5510
.
Feng
G.
,
Liu
L.
&
Tan
W.
2014
Effect of thermal hydrolysis on rheological behavior of municipal sludge
.
Industrial & Engineering Chemistry Research
53
,
85
92
.
Fytili
D.
&
Zabaniotou
A.
2008
Utilization of sewage sludge in EU application of old and new methods: a review
.
Renewable and Sustainable Energy Reviews
12
,
116
140
.
Gans
B. d.
,
Blom
C.
,
Philipse
A.
&
Mellema
J.
1999
Linear viscoelasticity of an inverse ferrofluid
.
Physical Review
60
,
4518
4527
.
Hammadi
L.
,
Ponton
A.
&
Belhadri
M.
2013
Temperature effect on shear flow and thixotropic behavior of residual sludge from wastewater treatment plant
.
Mechanics of Time-Dependent Materials
17
,
401
412
.
Jiang
J.
,
Wu
J.
,
Poncin
S.
&
Li
H. Z.
2014
Rheological characteristics of highly concentrated anaerobic digested sludge
.
Biochemical Engineering Journal
86
,
57
61
.
Ksapabutr
B.
,
Gulari
E.
&
Wongkasemjit
S.
2004
Sol-gel transition study and pyrolysis of alumina-based gels prepared from alumatrane precursor
.
Colloids Surfaces A
233
,
145
153
.
Milhé
M.
,
Charlou
C.
,
Sauceau
M.
&
Arlabosse
P.
2015
Modeling of sewage sludge flow in a continuous paddle dryer
.
Drying Technology
33
,
1061
1067
.
Mouzaoui
M.
,
Baudez
J. C.
,
Sauceau
M.
&
Arlabosse
P.
2018
Experimental rheological procedure adapted to pasty dewatered sludge up to 45% dry matter
.
Water Research
133
,
1
7
.
Nommensen
P.
,
Duits
M.
,
van den Ende
D.
&
Mellema
J.
1999
Steady shear behavior of polymerically stabilized suspensions: experiments and lubrication based modeling
.
Physical Review E Statistical Physics, Plasmas, Fluids, and Relat. Interdisciplinary Topics
59
,
3147
3154
.
Ortiz
M.
,
De Kee
D.
&
Carreau
P. J.
1994
Rheology of concentrated poly(ethylene oxide) solutions
.
Journal of Rheology
38
,
519
.
Pevere
A.
,
Guibaud
G.
,
Goin
E.
,
van Hullebusch
E.
&
Lens
P.
2009
Effects of physico-chemical factors on the viscosity evolution of anaerobic granular sludge
.
Biochemical Engineering Journal
43
,
231
238
.
Quignon-Tosoni
J.
2015
Rhéologie des Matériaux Pâteux: Vers un Continuum des Régimes Solide et Liquide. Application aux Boues Résiduaires
.
Thèse en Génie des procédés
,
Blaise Pascal – Clermont-Ferrand, France
.
Sato
J.
&
Breedveld
V.
2005
Evaporation blocker for cone-plate rheometry of volatile samples
.
Applied Rheology
15
,
390
397
.
Ségalen
C.
2015
Complémentarité des Propriétés Electriques et Rhéologiques Pour une Caractérisation des Boues Résiduaires
.
Thèse en Génie des procédés
,
Université Blaise Pascal – Clermont-Ferrand, France
.
Xue
Y.
,
Liu
H.
,
Chen
S.
,
Dichtl
N.
,
Dai
X.
&
Li
N.
2015
Effects of thermal hydrolysis on organic matter solubilization and anaerobic digestion of high solid sludge
.
Chemical Engineering Journal
264
,
174
180
.