Abstract
The right individuation of the more convenient solution for final treatment and destination of sewage sludge deriving from
wastewater plants, normally after anaerobic digestion process, is a very interesting problem, in accounting of urgent needs for
acceptable solutions. The produced sludge, primarily after thermal drying, can be sent to energetic valorization processes as, for
example, incineration, gasification and also pyrolysis. In this work we examined the thermal solutions (both direct combustion in
incineration plant and gasification), for the sewage sludge deriving from the main Italian wastewater plants (ubicated in the
metropolitan area of Turin), from both technological and environmental point of view. The plant actually produces about 100,000
t/y of sludge (38.9% d.s. (dry sludge)), in three main streams: centrifuged sludge, filtered sludge and thermal dried sludge. The
water content of the streams is obviously different, while the indicated humidity is a mean value.
In order to propose a solution for sludge valorization, a first analysis was carried out in order to define the main characteristics of
the produced sludge (flow rates and composition); afterwards we analyzed in detail the potential plant design solutions, from the
technological and the environmental point of view, achieving some perspectives in terms odd design data.energy recovery, gasification, incineration, pyrolysis, sludge, thermal treatment