Effects of Freezing Rate, Solids Content, and Curing Time on Freeze/Thaw Conditioning of Water Treatment Residuals

Parker, Philip J.; Collins, and Anthony G.; Dempsey, J. P.

doi:10.1021/es970603j

Cited by 23 publications

(14 citation statements)

References 13 publications

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“…Cell lysis upstream of digestion has been a topic of interest for researchers looking for methods to improve digestion processes by modifying WAS upstream of digestion. Freeze-thaw methods (Parker et al, 1998) have been found effective to transform residuals from semisolids to slurries with visible free water, but only after the sample has been allowed enough curing time. By freezing bulk sludge, Hu et al (2011) found COD solubilization was heavily dependent on sludge curing time.…”

Section: Introductionmentioning

confidence: 99%

Investigations into Improving Dewaterability at a Bio‐P/Anaerobic Digestion Plant

Alm

Sealock

Nollet

et al. 2016

Water Environment Research

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Metropolitan Council Environmental Services has observed poorer than expected dewatering performance at its Empire Plant. This plant has both anaerobic digestion and enhanced biological phosphorus removal in its treatment train. A research program using pilot-scale anaerobic digesters investigated potential solutions to the plant's poor dewaterability. The dewaterability goal was to increase the cake solids from 12% total solids (TS) to 16% TS or higher. This research investigated 20 different reactor conditions including chemical, feed sludge, and digested sludge treatments. At the pilot scale, unaerated storage of waste activated sludge prior to thickening and addition of ferric chloride to digestion was found to achieve dewatered cake solids of nearly 17% TS with the added benefit of reducing polymer demand. Issues including the amount of chemical required and the resulting volatile solids destruction influence the viability of the process change, so a full-scale pilot and financial analysis is recommended before making permanent process changes.

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Section: Introductionmentioning

confidence: 99%

Investigations into Improving Dewaterability at a Bio‐P/Anaerobic Digestion Plant

Alm

Sealock

Nollet

et al. 2016

Water Environment Research

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“…In this study, the salinity of sludge was tested at three levels (5000, 10 000 and 20 000 ppm, which corresponds to half of, equal to, and twice the average value of the salinity in the sludge samples, respectively). In preparing the sludge with a salinity of 5000 ppm, 800 mL of original sludge was centrifuged (Allegra 6 Centrifuge, Beckman) at 1000 rpm equivalent to 228 G for 30 min to separate the sludge into two layers: the supernatant and the concentrated sludge (15). The supernatant was replaced with equal amounts of deionized water.…”

Section: Experimental Methodsmentioning

confidence: 99%

Salinity Effect on Mechanical Dewatering of Sludge with and without Chemical Conditioning

Imc

Lai

Chen

2001

Environ. Sci. Technol.

125

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The salinity levels of wastewater and sludge are relatively high in some coastal cities as they may use saline water for toilet flushing, and as such,the sludge dewaterability can be affected by it. The salinity effect on sludge dewaterability was therefore investigated through experimental testing of specific resistance in filtration (SRF), time to filter (TTF), and final solid content of sludge. SRF and TTF were determined using Buchner funnel tests. The final solid content was estimated by centrifuging the sludge at four levels of rotational speed. Sludge with three salinity levels (5,000, 10,000 and 20,000 ppm) were considered in this study. Coagulants such as alum, iron(II) sulfate, and organic polyelectrolytes were added to the sludgetostudythe dewaterability of such sludge with chemical conditioning. Experimental results show that doubling the salinity level of the sludge from 10,000 to 20,000 ppm shows not much change in SRF and TTF. Compared with the sludge without chemical conditioning, the addition of the coagulants to the sludge at a salinity level of 5,000 ppm drastically reduces its SRF and TTF. However, sludge with and without chemical conditioning at a salinity of 20,000 ppm has similar SRF and TTF. The final solid content of sludge increases almost linearly with salinity. Among the coagulants used in this study, the cationic polyelectrolyte is found to be better in improving sludge dewaterability, while iron(II) sulfate performs slightly better in enhancing the final solid content of the sludge.

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“…In a study of freeze-thaw conditioning of water treatment residuals, Parker et al (1998) found that freezing rate did not affect the final dewaterability. However, they found that the initial solids content and curing time had a noticeable effect.…”

Section: Biosolids and Sludge Characteristicsmentioning

confidence: 99%

Simulating disinfection processes in chlorine contact tanks using various turbulence models and high-order accurate difference schemes

Wang

Falconer

1998

Water Research

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Effects of Freezing Rate, Solids Content, and Curing Time on Freeze/Thaw Conditioning of Water Treatment Residuals

Cited by 23 publications

References 13 publications

Investigations into Improving Dewaterability at a Bio‐P/Anaerobic Digestion Plant

Investigations into Improving Dewaterability at a Bio‐P/Anaerobic Digestion Plant

Salinity Effect on Mechanical Dewatering of Sludge with and without Chemical Conditioning

Simulating disinfection processes in chlorine contact tanks using various turbulence models and high-order accurate difference schemes

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