EFFECT OF MODERN TREATMENT PROCESSES AND CHEMICAL DOSING ON SLUDGE RHEOLOGY
Mick Dawson1, Thanos Sotiriadis2
1BHR Group Limited
2Shaw Group, Stone & Webster
(free)
Rheological parameters are one of the most important measures of the physical consistency
of sludges. Due to the different composition of sludges, their rheological behaviour varies
between sludge types and between sites. There is a clear lack of a reliable sludge rheological
data in the literature for process design work, particularly for sludges resulting from new
processes adopted by the water industry. These new sludge types include hydrolysed and
pasteurised sludges as well as chemical/polymer-dosed sludges.
Rheological properties affect all aspects of handling including thickening, dewatering,
agitation/mixing, heat transfer and most importantly pumping The benefits of quantifying
sludge flow behaviour include:
• Reduced risk of costly equipment failure
• Lower Capex through elimination of over-design
• Lower power and maintenance costs through improved equipment selection & sizing
The BHR Sludge Rheology Database (SRDB) provides the most comprehensive collection of
sludge rheology data anywhere in the world. Use of the database has enabled improved
property prediction for a wider range of sludge types than the extensively used WRc Report
TR185.
In this paper we describe the practical application of the BHR SRDB for predicting sludge
rheological properties. In addition, we use the database as a tool to investigate the effect on
sludge rheological properties of:
• Dosing Fe salts for P removal
• Various thickening approaches
• Hydrolysis
KEY WORDS
Sludge Rheology, Rheology Database, Sludge Pumping, Sludge Mixing
