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Appraisal of changes in sewage sludge management
Vochozka, M.; Maroušková, A.; Váchal, J. & Straková, J.
Abstract
A positive energy balance caused by accelerated
production of CH4 and additional financial benefits
associated with shorter retention times, reduction in volumes,
easier dewatering, enhanced hygiene, etc., are the
reasons why most modern wastewater treatment plants are
newly equipped with hydrothermal pretreatment units. This
study examined how the changes in composition of the
pretreated sewage sludge fermentation residues manifested
themselves in subsequent processing by pyrolysis, both in
terms of technology and financial impacts. It has been
found that concentrations of heavy metals and other hazardous
inhibitors might increase; however, the overall
biotoxicity is lower due to their immobilization in the
charred mass. Moreover, charring of the fermentation
residues results in significant financial as well as technological
benefits.
Keywords
Sewage sludge management; Hydrothermal decomposition; Cost analysis; Environmental policy
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