Sludge management – future issues and trends

Abstract

A review of the literature over the last thirty years shows that while the diversity of unit processes for sludge treatment has increased dramatically, there are still only three basic ultimate disposal routes for processed sludge; land application, landfill and incineration. None of these end-uses are fundamentally either good or bad; each one is simply more or less appropriate for a given situation. Selection of a sludge management option is not immune to popular trends and this may introduce artificial criteria as opposed to having the choice based on a critical evaluation of the needs of each specific project.We must ensure that efforts to promote one approach to sludge management does not inadvertently create new obstacles for alternative solutions. For example, landapplication of sludge is enjoying a well-deserved period of growth based on good science, cleaner sludges and proactive public education. However, we must not fall into the trap of assuming that this is the only “good” approach and discounting other potential solutions without a unbiased assessment. This paper summarizes the major trends in sludge management from the perspective of both the past and the present. Issuesrelated to current practice and future developments are discussed with reference as to how they may impact on future sludge management decisions. Sludge management alternatives should be selected based on consideration of the following elements: multiple use options provide the producer with flexibility to respond to changing priorities, the solution must reflect the unique needs of the individual community and the public must be incorporated into the decision making process from the very beginning.