Moisture distribution in activated sludges: a review

Vaxelaire, Jean; Cézac, Pierre

doi:10.1016/j.watres.2004.02.021

Cited by 346 publications

(128 citation statements)

References 47 publications

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“…Therefore, the development of high performance dewatering processes has been one of the most important research areas in current China. In general, the moisture in sludge system can be classified into free water (accounted for about 70 wt%), interstitial water (about 20 wt%), adsorbed water (about 7 wt%) and bound water (about 3 wt%) (Vaxelaire and Cezac, 2004). Except for sludge properties, the dewatering performance was mainly dependent on selection of sludge devices and chemical conditioning methods (Beauchesne et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

et al. 2016

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a b s t r a c tThe effects of combined calcium peroxide (CaO 2 ) oxidation with chemical re-flocculation on dewatering performance and physicochemical properties of waste activated sludge was investigated in this study. The evolutions of extracellular polymeric substances (EPS) distribution, composition and morphological properties were analyzed to unravel the sludge conditioning mechanism. It was found that sludge filtration performance was enhanced by calcium peroxide oxidation with the optimal dosage of 20 mg/ gTSS. However, this enhancement was not observed at lower dosages due to the absence of oxidation and the performance deteriorated at higher dosages because of the release of excess EPS, mainly as proteinlike substances. The variation in soluble EPS (SEPS) component can be fitted well with pseudo-zero-order kinetic model under CaO 2 treatment. At the same time, extractable EPS content (SEPS and loosely bound EPS (LB-EPS)) were dramatically increased, indicating sludge flocs were effectively broken and their structure became looser after CaO 2 addition. The sludge floc structure was reconstructed and sludge dewaterability was significantly enhanced using chemical re-flocculation (polyaluminium chloride (PACl), ferric iron (FeCl 3 ) and polyacrylamide (PAM)). The inorganic coagulants performed better in improving sludge filtration dewatering performance and reducing cake moisture content than organic polymer, since they could act as skeleton builders and decrease the sludge compressibility.

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Section: Introductionmentioning

confidence: 99%

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

et al. 2016

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“…Sludge dewaterability was evaluated in terms of the water content in dewatered sludge (W C ). The W C was calculated as follows: 21 With a certain amount of dewatered sludge in the DSC analyzer (NETZSCH, 404 F3 Pegasus, Germany), sludge samples were cooled down to À30 C at a rate of 5 C min À1 , and then warmed up to room temperature at the same rate. Theoretically, samples would release heat and show a signicant exothermic peak in the process of freezing and present a clear endothermic peak at heating stage.…”

Section: Experimental Methodsmentioning

confidence: 99%

Effect of surfactant on bound water content and extracellular polymers substances distribution in sludge

Hong

Xing

et al. 2015

RSC Adv.

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In this study, the effect of surfactant conditioning on bound water and extracellular polymers substances (EPS) in sludge was investigated.Results showed that by adding dodecyl dimethyl benzyl ammonium chloride (DDBAC), loosely bound EPS (LB-EPS) and slime layer EPS (S-EPS) contents were increased, while tightly bound EPS (TB-EPS) and bound water contents (W B ) were reduced. As a result, the dewatering performance of sludge was enhanced. When 75 mg g À1 of DDBAC were added, W B in sludge decreased to 1.64 g g À1 , and the water content of dewatered sludge (W C ) dropped to 66.61%. EPS partially hydrolyzed into small molecular organics under DDBAC conditioning.Moreover, the quantity and species of organic functional groups in S-EPS were increased obviously. The TB-EPS content accounted for the majority of EPS in sludge, and the protein and polysaccharide in TB-EPS had a significant positive correlation with bound water, which was the main factor affecting W B in sludge.

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“…High-performance dewatering has been proven to be an efficient method to reduce sludge volume, cutting transportation and disposal cost (Neyens et al, 2004). Generally, the moisture in activated sludge can be classified into free water (about 70%), interfacial water (about 20%) and bound water (about 10%) (Vaxelaire and Cezac, 2004). Except for the sludge characteristics, the dewatering efficiency was mainly dependent on the selection of device and chemical conditioning process.…”

Section: Introductionmentioning

confidence: 99%

Improvement of wastewater sludge dewatering performance using titanium salt coagulants (TSCs) in combination with magnetic nano-particles: Significance of titanium speciation

et al. 2017

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a b s t r a c tIn this study, the effects of chemical conditioning using titanium salt coagulants (TSCs) of different hydrolysis speciation in combination with magnetic nano-particles on dewatering performance of waste activated sludge were evaluated by means of specific resistance to filtration (SRF) and capillary suction time (CST). The morphological and extracellular polymeric substances (EPS) properties under chemical conditioning were investigated in detail to understand the reaction mechanisms involved. The results showed that the TSC with basicity of 0.5 performed better in improving sludge dewatering performance than other TSCs. Sludge floc formed by TSC 0.5 treatment was characterized by larger floc size and higher floc strength than that conditioned by other TSCs. EPS compression and densification were the major mechanisms of sludge conditioning, and TSC 0.5 had better performance in compressing EPS structure. In addition, reduction of soluble EPS concentration, especially protein-like substances contributed to improvement of sludge filterability under conditioning. Furthermore, addition of Fe 2 O 3 nanoparticles could further improve dewatering performance and decrease compressibility of sludge system by acting as skeleton builders and enhancing floc strength. The sludge particles aggregation efficiency was effectively improved with addition of nano-Fe 2 O 3 . They also were able to bind with protein-like substance in EPS component, which might contribute to promotion of sludge filterability.

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Moisture distribution in activated sludges: a review

Cited by 346 publications

References 47 publications

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

Effect of surfactant on bound water content and extracellular polymers substances distribution in sludge

Improvement of wastewater sludge dewatering performance using titanium salt coagulants (TSCs) in combination with magnetic nano-particles: Significance of titanium speciation

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