Dewatering characteristics of alum sludge under low compressive pressure

K. Gotoh, O. Nishimura, A. Satoh, H. Satoh

Research output: Contribution to journalArticlepeer-review


In this study, the constant-rate strain compression test was proposed to evaluate dewatering characteristics of alum sludges under low compressive pressure (below 50 kPa), and 13 kinds of alum sludges including one biofilm process sludge and polymer conditioned sludges were used for this test. From these results, it is confirmed that storage capacity of pore water in sludge under low compressive pressure depends upon SiO2/Al2O3 and organic matter in raw water. At the same effective pressure, equilibrium porosity of conditioned alum sludge with cationic polymer is not so different from that of unconditioned sludge. On the other hand, kSo2 of conditioned sludge remarkably decreases as compared with unconditioned sludge, and it is clear that sludge conditioning affects the floc structure of alum sludge. Each local specific resistance αx of conditioned sludges is close to that of unconditioned sludge with the increase of compressive pressure, therefore improvement of dewaterbility by conditioning is remarkably in low compressive pressure range. These results have much interest to consider the efficiency of dewatering process.

Original languageEnglish
Pages (from-to)547-556
Number of pages10
JournalWater Supply
Issue number3-4
Publication statusPublished - 1990

ASJC Scopus subject areas

  • Engineering(all)


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