Flocculation Effects on Bound Water in Sludges as Measured by Nuclear Magnetic Resonance Spectroscopy

Carberry, J. B.; Prestowitz, Robert A.

doi:10.1128/aem.49.2.365-369.1985

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…indicating that at the same concentration, water is becoming more accessible when polymer is added. This is in agreement with the literature in which an increase of the amount of free water is reported when some chemical conditioners are added to sludge [16,19,30,31]. To explain this behavior, these papers suggested that chemical conditioners act either by replacing water molecules adsorbed on the particle surface or by affecting the water binding capacity to the particle [16,31].…”

Section: Viscoelastic Properties and Water Activity Dependence With Ssupporting

confidence: 90%

“…EPS are highly charged polymers that interact with water in a similar way as gels [10][11][12][13], influencing the strength of the structure regarding the nature of interactions between solids and water which can be balanced between steric and electrostatic [35] As a consequence, great attention has been paid to water repartition within sludge. For example, extensive studies, largely reviewed by Vaxelaire and Cézac [14], have been performed to estimated water states within activated sludge by using several techniques such as : differential scanning calorimetry (DSC) [15], dilatometry [16,17], drying [16], combined thermal gravimetry analysis and differential thermal analysis [18], nuclear magnetic resonance spectroscopy [19], centrifugal settling [20] and desorption isotherms [21]. Based on these studies, four categories of water in sludge were classically distinguished:  Free water, which represents the largest part of the sludge.…”

Section: Introductionmentioning

confidence: 99%

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Using water activity measurements to evaluate rheological consistency and structure strength of sludge

Agoda-Tandjawa¹,

Dieudé-Fauvel²,

Girault³

et al. 2013

Chemical Engineering Journal

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In this study, an original method of characterization of water/solid matter interactions in sewage sludge has been developed, based on both rheological characteristics and thermodynamic water activity determinations, in order to check whether a link could be made with water activity and its mechanical properties. The effect of solid matter content, flocculation and ageing time on water activity and rheological parameters has been investigated. Through this study, we showed that rheological parameters (G’ and G’’) of both raw and flocculated sewage sludge at optimal dose of polymer increase with solids concentration following a power-law, whereas in the same way water activity decreases following an exponential relationship (Arrhenius dependence). A slight increase of water activity values and those of G’ and G’’ moduli with added polymer was also highlighted. On the other hand, we have shown that during ageing, the rheological parameters G’ and G’’ decreased upon increasing the ageing time whereas in the same way, water activity increases. Rheological parameters clearly evidenced thermodynamic water activity dependence, regarding solid concentration and ageing time, with a decrease of G’ and G’’ upon increasing water activity. Thus, water/solid matter interactions were supposed to intervene importantly in the rheology of sewage sludge. From all these results, it appears clearly that water activity measurements can be regarded as an effective and easy tool for evaluating the state of structuration of sewage sludge and for predicting its structural, textural and mechanical properties during dewatering and ageing

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Section: Viscoelastic Properties and Water Activity Dependence With Ssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Using water activity measurements to evaluate rheological consistency and structure strength of sludge

Agoda-Tandjawa¹,

Dieudé-Fauvel²,

Girault³

et al. 2013

Chemical Engineering Journal

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“…The wetter the sample, the more unfrozen water it contained. A similar conclusion was reached by Carberry and Prestowitz (1985) who used nuclear magnetic resonance spectroscopy to measure bound water in sludges.…”

Section: Particle Sizesupporting

confidence: 71%

The role of water in sludge dewatering

Vesilind¹

1994

Water Environment Research

200

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While the dewatering of wastewater sludges has received considerable research attention, it has been assumed that the water con tinuum surrounding the sludge particles has the physical properties of bulk water. This paper suggests that such an assumption may not be valid. The existence of vicinal water, consisting of ordered and layered water molecules on the surfaces of submerged solids, is demonstrated using research from various disciplines. The meaning of "bound water" as used in sludge technology is discussed, and it is shown that bound water can be defined in several ways, depending on the test used. It seems reasonable that bound water as it is usually defined actually consists of three different types of water-water captured in the interstitial spaces within floes and within cells, vicinal water on the surfaces of solids, and water of hydration. Only some of the interstitial water can be removed by mechanical dewatering. Because of the large surface area of sludge particles, including living cells, it is likely that much of the bound water is vicinal water, and this cannot be removed mechanically. The deter mination of the various fractions of these waters may lead to a better understanding of mechanical sludge dewatering.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Water Environ. Res., zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF 66,4(1994).

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“…In terms of conditioning, it has been demonstrated by a number of authors that adding conditioner leads to a significant reduction of the bound water content, demonstrating the positive effect of chemical conditioning on water distribution (Halde 1979;Carberry & Prestowitz 1985). However, overdosed conditioning may cause an increase in bound water due to the absorption of moisture onto the polymer particles (Chu & Lee 1999).…”

Section: Moisture Content and Sludge Conditioning And Dewateringmentioning

confidence: 99%

A review on sludge dewatering indices

Nguyễn

Vigneswaran

et al. 2016

Water Science and Technology

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Dewatering of sludge from sewage treatment plants is proving to be a significant challenge due to the large amounts of residual sludges generated annually. In recent years, research and development have focused on improving the dewatering process in order to reduce subsequent costs of sludge management and transport. To achieve this goal, it is necessary to establish reliable indices that reflect the efficiency of sludge dewatering. However, the evaluation of sludge dewaterability is not an easy task due to the highly complex nature of sewage sludge and variations in solid-liquid separation methods. Most traditional dewatering indices fail to predict the maximum cake solids content achievable during full-scale dewatering. This paper reviews the difficulties in assessing sludge dewatering performance, and the main techniques used to evaluate dewatering performance are compared and discussed in detail. Finally, the paper suggests a new dewatering index, namely the modified centrifugal index, which is demonstrated to be an appropriate indicator for estimating the final cake solids content as well as simulating the prototype dewatering process.

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Flocculation Effects on Bound Water in Sludges as Measured by Nuclear Magnetic Resonance Spectroscopy

Cited by 12 publications

References 11 publications

Using water activity measurements to evaluate rheological consistency and structure strength of sludge

Using water activity measurements to evaluate rheological consistency and structure strength of sludge

The role of water in sludge dewatering

A review on sludge dewatering indices

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