Conditioning effect of lysozyme combined with freeze-thaw on the municipal sludge dewatering performance

The effects of lysozyme (LZM) and freeze-thaw conditioning, alone or in combination, on sludge dewatering performance were comparatively investigated. After the optimization of the dewatering conditions using response surface methodology (RSM), the co-conditioning exhibited obvious superiority to the separate conditioning in improving the dewaterability of municipal sludge, with the capillary suction time (CST) and the water content (W) of the dewatered sludge reduced to 12 ± 0.5 s and 52.0% ± 0.4% from 61.8 s and 73.0%, respectively. The co-conditioning appeared not only to destroy the structure of extracellular polymeric substance (EPS) and microbial cell wall by virtue of enzymatic conditioning, but it formed larger particles and compact sludge ﬂoc structure with the help of freeze-thaw conditioning. Additionally, the bound water content of sludge decreased by 47.5% after co-conditioning, consistent with the enhancement in sludge dewaterability. All the results showed that LZM in combination with freeze-thaw conditioning had a great potential in sludge reduction, providing more opportunity of resource utilization for the dewatered sludge.

Download Full-text

Effect of charge neutralization on the dewatering performance of alum sludge by polymer conditioning

Water Science & Technology ◽

10.2166/wst.2001.0650 ◽

2001 ◽

Vol 44 (10) ◽

pp. 315-319 ◽

Cited By ~ 13

Author(s):

C.C. Wu ◽

J.J. Wu

Keyword(s):

Water Content ◽

Bound Water ◽

Cationic Polymer ◽

Anionic Polymer ◽

Capillary Suction ◽

Potential Measurement ◽

Charge Neutralization ◽

Floc Structure ◽

Alum Sludge ◽

Bound Water Content

Cationic and anionic polymers with the same molecular weight were used as sludge conditioning reagent to study the polymer charge effect on alum sludge dewatering characteristics. On the basis of capillary suction time, bound water content, and zeta-potential measurement in this study, the function of charge neutralization appears to be an important consideration in the sludge dewaterability and moisture content. Using the dilatometric technique to measure the bound water content, we found that alum sludge conditioned by cationic polymer presented more significant variation in the bound water content than sludge subject to anionic conditioning. We hypothesise that the mechanism of charge neutralization caused much water depletion by replacement and exclusion in sludge and results in the decrease of bound water within the cationic polymer conditioning. An insignificant bound water variation found during the anionic conditioning resulted from the lack of charge neutralization. A lighter and looser floc structure is also be found in the anionic conditioned sludge after the analysis of wet floc density and fractal dimension. Such open floc structure can be attributed to the lack of charge neutralization as the flocs aggregate with anionic polymer.

Download Full-text

Capillary suction time (CST) as a measure of sludge dewaterability

Water Science & Technology ◽

10.2166/wst.1996.0462 ◽

1996 ◽

Vol 34 (3-4) ◽

pp. 443-448 ◽

Cited By ~ 38

Author(s):

G. W. Chen ◽

W. W. Lin ◽

D. J. Lee

Keyword(s):

Water Content ◽

Specific Resistance ◽

Bound Water ◽

The Other ◽

Solid Concentration ◽

Capillary Suction ◽

Good Index ◽

Other Hand ◽

Sludge Dewaterability ◽

Bound Water Content

The feasibility of employment of capillary suction time (CST) for characterizing the dewaterability of excess activated sludges was examined. The CST was shown as a good index for sludge filterability, if only the product of solid concentration and average specific resistance is of interest. On the other hand, the bound water content cannot be directly evaluated from the CST data.

Download Full-text

Bound Water Content of Activated Sludge and Its Relationship to Solids Retention Time, Floc Structure, and Surface Properties

Water Environment Research ◽

10.2175/106143000x138346 ◽

2000 ◽

Vol 72 (6) ◽

pp. 722-730 ◽

Cited By ~ 23

Author(s):

B.Q. Liao ◽

D.G. Allen ◽

I.G. Droppo ◽

G.G. Leppard ◽

S.N. Liss

Keyword(s):

Activated Sludge ◽

Water Content ◽

Surface Properties ◽

Retention Time ◽

Bound Water ◽

Floc Structure ◽

Solids Retention Time ◽

Solids Retention ◽

Bound Water Content

Download Full-text

Comparative Analysis of the Measurement Methods of Bound Water Content in Municipal Sewage Sludge

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.2991 ◽

2012 ◽

Vol 518-523 ◽

pp. 2991-2995

Author(s):

Wei Jun Zhang ◽

Ke Chun Sun

Keyword(s):

Comparative Analysis ◽

Sewage Sludge ◽

Water Content ◽

Bound Water ◽

Measurement Methods ◽

Municipal Sewage ◽

Municipal Sewage Sludge ◽

Sludge Dewatering ◽

Advantages And Disadvantages ◽

Bound Water Content

The dewatering of municipal sewage sludge is a current problem due to the huge production of this waste. The bound water content in sludge is closely related to the sludge dewatering performance. By comparative analysis of the measurement methods of the bound water content in sludge, this article points out their respective advantages and disadvantages, as well as the respects which should be noted in practice.

Download Full-text

Effects of thermal hydrolysis temperature on physical characteristics of municipal sludge

Water Science & Technology ◽

10.2166/wst.2015.425 ◽

2015 ◽

Vol 72 (11) ◽

pp. 2018-2026 ◽

Cited By ~ 8

Author(s):

Guohong Feng ◽

Yabing Guo ◽

Wei Tan

Keyword(s):

Particle Size ◽

Water Content ◽

Newtonian Fluid ◽

Bound Water ◽

Flow Index ◽

Thermal Hydrolysis ◽

Municipal Sludge ◽

Hydrolysis Temperature ◽

Bound Water Content ◽

Fluid Characteristics

Effects of thermal hydrolysis temperature on the physical properties of municipal sludge was further studied by a series of experiments. There was a decrease in bound water content with an increase in hydrolysis temperature, while there was an increase in pH at temperatures below 120 °C, and a decrease at temperatures exceeding 120 °C. An analysis of settleability, centrifugation and vacuum filtration of the treated sludge indicated that the threshold temperature was 120 °C, which was the same as the temperature for the bound water content and particle size. In addition, raw sludge with a solids content of 100 g/L, exhibited significant non-Newtonian fluid characteristics. At thermal hydrolysis temperatures exceeding 120 °C, non-Newtonian fluid characteristics including liquid and solid characteristics were significantly weakened. The consistency index (k) decreased from 5.90 Pa·s to 0.068 Pa·s, while the flow index (n) increased from 0.31 to 0.74, suggesting that thermal hydrolysis sludge was much closer to Newtonian fluids compared to raw sludge. Modification of bound water content, particle size and viscosity with hydrolysis temperature, revealed the nature of improved dewaterability by thermal hydrolysis. The fractal dimension of the sludge floc increased from 2.74 to 2.90, meaning that the floc became more compact after thermal hydrolysis.

Download Full-text