Multicriteria Assessment of Alternative Sludge Disposal Methods

Sludge production from wastewater treatment process is high, and the disposal of excess sludge will be forbidden in a near future, thus increased attention has been turned to look into potential technology for sludge reduction. The study attempts to review alternative sludge disposal methods, including anaerobic digestion, aerobic digestion and landfills. In these sludge processes, excess sludge production can be reduced up to 100% without significant effect on process efficiency and stability. Current waste water sludge production in U.K amounts to around 1.2 megatonnes of dry solids each year and for EU as a whole there are about 6.5 megatonnes of dry solids produced annually. The sludge production values has significantly increased, possibly by as much as 50%, as the urban waste water treatment directive was implemented over the period up to 2005 and in the next decade, sludge disposal to all the established outlets could become increasingly difficult. The challenges faced by the government are how to (a) maintain costeffective and secure methods of sludge disposal and (b) engender public confidence in all disposal and recycling options. This study would be useful when one is looking for appropriate environmentally and economically acceptable solutions for reducing or minimizing excess sludge production from wastewater treatment process. Here is the comparison of Sludge disposal methods i.e Anaerobic, Aerobic and Landfills, and carry out the research to find out the cost effective, calorific value and more environment friendly methods like labour cost, capital cost, Operating Cost, Process Time, Space requirement, Odours, Energy Balance, Biogas Production, Sludge production, Energy Cost, Reactor Volume, Application, BOD Reduction and Reliability. Studying the anaerobic, aerobic and landfill methods of sludge disposal and taking into account the survey and case study of Scottish Water’s waste water treatment site Cumnock WWTW to conclude the best suitable method for sludge disposal.