IMPROVING PREDICTION OF SLUDGE PUMPING LOSSES & MIXING ENERGY.
*Dawson M,. and **Harrison D
*BHR Group Limited, ** Monsal Limited
(free)
Over the last decade, the development of new sewage and sludge treatment processes has resulted in a growing number of sludge types whose rheological properties (flow behaviour) cannot be adequately predicted using existing published rheology data such as WRCs TR185 ‘How to Design Sewage Sludge Pumping Systems’. Examples include polymer thickened sludges and sludges that have been subjected various pasteurisation or hydrolysis processes.
The cost effective design, sizing or selection of equipment for sludge pumping, transport, handling, mixing, thickening, de-watering, heat exchange and other processing depends on reliable sludge rheology measurement or prediction. In this work we illustrate the errors inherent in the use of existing sludge rheology prediction methods for polymer thickened and pasteurised sludges and show examples of the effect of these errors on pump and mixer sizing.
We go on to outline the approach being taken by BHR Group Limited, in the WWM 5 research project, for the construction of a comprehensive sludge rheology database that will enable the development of improved sludge rheology prediction tools for a range of sludges including polymer thickened and pasteurised sludges. The new database will be established from a combination of existing data and sludge samples obtained from WWM 5 members and measured in the BHR rheology laboratory.
KEY WORDS: Sludge, Rheology, Pumping, Mixing.
