Ultra-rapid freezing of water treatment residuals

Parker, Philip J.; Collins, Anthony

doi:10.1016/s0043-1354(98)00449-7

Cited by 24 publications

(21 citation statements)

References 20 publications

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“…The resulting aggregates are smaller and denser, and they resemble the alum sludge aggregates. Parker and Collins [69] considered that ultra-rapid freezing of sludge could improve its dewaterability. Their fastest freezing rate was 37.5 mm/h, and after such treatment, the CST could be decreased from 50 to 200 s to about 10 s. They thought the result of improving dewaterability was that ultra-rapid freezing could dehydrate sludge flocs while they were entrapped within the ice.…”

Section: Other Methods To Treat Sludgementioning

confidence: 99%

A review on the dewaterability of bio-sludge and ultrasound pretreatment

Xia¹,

Han²,

Luo³

et al. 2004

Ultrasonics Sonochemistry

151

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Bio-sludge, which contains large quantities of water, biomass and extracellular polymeric substances (EPS), is difficult to be dewatered as a "super-compactable" sludge [Water Res. 35 (5) (2001) 1358]. Reported water content in bio-sludge was commonly about 80-90% wt after dewatering process. The EPS and the form of water in sludge influences the structure of sludge. Adding cationic fluctuations can change the form of water in sludge and increase the velocity of dewatering process, but has little influence on the final water content. According to Bien's work [Water Sci. Technol. 36 (4) (1997) 287], a combination of ultrasound or other method could agglomerate the sludge, improve the activities of biomass [Ultrasonics 38 (2000) 711; Ultrasonics 40 (2002) 25], enhance anaerobic process [Water Sci. Technol. 36 (11) (1997) 155; Water Sci. Technol. 36 (11) (1997) 121; Water Res. 35 (8) (2001) 2003; Water Sci. Technol. 36 (12) (1997) 117] and decrease over 10% final water content of sludge. The mechanisms of ultrasonic influence on sludge are not very clear, but the application of ultrasound to industrial process is relatively easy and possible.

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Section: Other Methods To Treat Sludgementioning

confidence: 99%

A review on the dewaterability of bio-sludge and ultrasound pretreatment

Xia¹,

Han²,

Luo³

et al. 2004

Ultrasonics Sonochemistry

151

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“…Free water removal typically occurs via unassisted gravity sedimentation (although flotation is possible) and yields products containing up to 15% solids. Some free, interstitial and surface water can be removed mechanically, e.g., by centrifuge, freeze-thaw cycles and/or application of polyelectrolyte surfactants, to achieve 15-30% solids content (e.g., Lee and Jean, 1999;Parker and Collins, 1999;Chen et al, 2001). Solid content in the same range results from accretion or encrustation (Dudeney, et al).…”

Section: Theorymentioning

confidence: 99%

Characterisation of iron-rich sludge: correlations between reactivity, density and structure

Georgaki

Dudeney

Monhemius

2004

Minerals Engineering

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This paper discusses the behaviour of iron-rich sludge, a problematic waste product of potable water treatment, minewater/groundwater management and hydrometallurgical processing. The work confirmed the highly hydrous and largely amorphous nature of the sludge and the significant differences that occur in reactivity (rate of acid leaching) and density (densification) depending variously upon the mode of sludge formation, pre-conditioning and storage. A structural study using a combination of FT-IR / ATR, XRD and TG/DTA correlated decreases in reactivity with ageing (i.e., with increases in particle size and/or degree of crystallinity) and increases in density with expulsion of weakly bonded water. The work underpinned studies on recycling of water treatment sludge with ion exchange resins and accelerated densification during sludge management.

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“…The residual polymers in dewatered sludge cakes may pose a long-term risk to the surrounding environment especially when the sludge cakes are subject to landfill as the final disposal, and it is usually very expensive (van der Roest et al, 1999). Thus, various alternative methods have been proposed to enhance the sludge dewatering characteristics, including the addition of acids and surfactants (Chen et al, 2001), Fenton's reagent pretreatment (Lu et al, 2003;Tony et al, 2008), microwave conditioning (Wojciechowska, 2005), ultrasonication (Bien, 1991;Bien and Wolny, 1997;Neis, 2000;Na et al, 2007;Feng et al, 2009), fry-drying technology (Ohm et al, 2009), and ultra-rapid freezing (Parker and Collins, 1999). Any new method will have to affect the water molecules-organic matter bonding.…”

Section: Introductionmentioning

confidence: 99%