Revised capillary suction time (CST) test to reduce consumable costs and improve dewaterability interpretation

Scholz, Miklas

doi:10.1002/jctb.1400

Cited by 14 publications

(6 citation statements)

References 12 publications

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“…This finding suggested that the dewaterability of sludge flocs from the leachate WWTPs was much poorer than that of sludge flocs from the other types of WWTPs. The normalized CST values of the other sludge flocs apart from the leachate WWTPs were similar to those reported by Scholz (20).…”

Section: Resultssupporting

confidence: 86%

Stratification Structure of Sludge Flocs with Implications to Dewaterability

Shao

et al. 2008

Environ. Sci. Technol.

354

111

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Sludge dewatering has proven to be an effective method to reduce the volume of sludge. In this study, a novel stratification approach aimed at better understanding the factors influencing the sludge dewaterability (as determined by capillary suction time, CST) was developed. The sludge flocs from 14 different full-scale wastewater treatment plants (WWTPs), including sewage, leachate, industry, and special-source sludge, were stratified through centrifugation and ultrasound into five layers: (1) supernatant, (2) slime, (3) loosely bound extracellular polymeric substances (LB-EPS), (4) tightly bound EPS (TB-EPS), and (5) pellet. The results showed that the distribution pattern of proteins (PN) in the sludge flocs differed from that of polysaccharides (PS). The normalized CST correlated with PN (R2 > 0.72, p < 0.01) and PN/PS (R2 > 0.51, p < 0.01) in the supernatant, slime, and LB-EPS, but not with PN and PN/ PS in the pellet and the sludge flocs as a whole or with PS in any of the fractions and or the sludge flocs as a whole. The results suggest that PN and PN/PS in the supernatant and slime layers, which are usually decanted due to their assumed lower content of organic matter, markedly impact sludge dewaterability.

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Section: Resultssupporting

confidence: 86%

Stratification Structure of Sludge Flocs with Implications to Dewaterability

Shao

et al. 2008

Environ. Sci. Technol.

354

111

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“…This theory is based on the material balance of the water and Darcy's law. The suction and the hydraulic conductivity of both the paper and the suspension are functions of the water content [7]. The introduction of a rectangular funnel is expected to improve the ease and accuracy of mathematical modelling of any CST data.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Capillary Suction Time (CST) Test Methodologies

Sawalha¹,

Scholz²

2007

Environmental Technology

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The capillary suction time (CST) test is a commonly used method to measure the filterability and the easiness of removing moisture from slurry and sludge in numerous environmental and industrial applications. This study assessed several novel alterations of both the test methodology and the current standard capillary suction time (CST) apparatus. Twelve different papers including the standard Whatman No. 17 chromatographic paper were tested. The tests were run using four different types of sludge including a synthetic sludge, which was specifically developed for benchmarking purposes. The standard apparatus was altered by the introduction of a novel rectangular funnel instead of a standard circular one. A stirrer was also introduced to solve the problem of test inconsistency (e.g. high CST variability) particularly for heavy types of sludge. Results showed that several alternative papers, which are cheaper than the standard paper, can be used to estimate CST values accurately, and that the test repeatability can be improved in many cases and for different types of sludge. The introduction of the rectangular funnel demonstrated an obvious enhancement of test repeatability. The use of a stirrer to avoid sedimentation of heavy sludge did not have statistically significant impact on the CST values or the corresponding data variability. The application of synthetic sludge can support the testing of experimental methodologies and should be used for subsequent benchmarking purposes.

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“…Accuracy of Specific Resistance to Filtration. When analyzing the CST data with linear regression, the corresponding slope of the predicted line of CST values regressed over the five ring numbers can be used to represent the SRF (Scholz, 2006;Sawalha and Scholz, 2007). Meeten and Lebreton (1993) previously have proven this.…”

Section: Resultsmentioning

confidence: 99%

Innovative Enhancement of the Design and Precision of the Capillary Suction Time Testing Device

Scholz

2009

Water Environment Research

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The capillary suction time (CST) test can be used as an alternative to predict the otherwise expensive, hard‐to‐run specific resistance to filtration test. One of the major drawbacks of the CST test, however, is relatively high variability of test results. The aim of this study was, therefore, to improve the product design by testing the effectiveness of using a funnel sealant to reduce variability. Use of a funnel sealant resulted in increased test precision. There was a reduction of up to 63% in the coefficient of variation and a substantial improvement in the predictability of the specific resistance to filtration test.

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Revised capillary suction time (CST) test to reduce consumable costs and improve dewaterability interpretation

Cited by 14 publications

References 12 publications

Stratification Structure of Sludge Flocs with Implications to Dewaterability

Stratification Structure of Sludge Flocs with Implications to Dewaterability

Assessment of Capillary Suction Time (CST) Test Methodologies

Innovative Enhancement of the Design and Precision of the Capillary Suction Time Testing Device

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