The Development of a Sludge Disposal Strategy for the Hong Kong Territories

Sludge arisings in the Hong Kong Territories are predicted to increase from the current level of 44 300 tDS/annum to 314000 tDS/annum. This has led to a need to examine the treatment and disposal facilities required for the future. Disposal facilities were found to be restricted, with virtually no suitable land for a liquid disposal route and a sea route limited to the present quantities. Only landfill remained as the major disposal outlet, but this is also limited by the moisture absorbence capacity of the emplaced material and limiting metal concentrations.
In order to match the sludge production to the disposal outlet capacity, a series of process options was considered. Transportation studies using pumping, road and sea networks were undertaken and the environmental impact assessment of introducing thermal technologies was reviewed. Finally the various options were evaluated using a modified version of the Water Research Centre's WISDOM model.