Chromium-Free Tannery Wastes Stabilized by Methane Fermentation in Sewage Treatment Plants’ Installations

Abstract

Due to the introduction of more stringent sanitary regulations in Poland, the possibility of processing waste raw materials into fodder and food additives has been limited. There has appeared a need to find other ways of their utilisation or neutralisation. The paper presents the results of research aimed at the examination of the possibility of chromium-free tannery wastes processing by methane fermentation. The susceptibility of various hides and skins processing wastes, i.e. protein (colagen and keratin) and grease wastes, to fermentation was studied. Various kinds of preliminary treatment (alkaline, acid, and thermal) were applied. Additionally, the content of nitrogen and phosphorus in postfermentation sludges and their susceptibility to dewatering and composting were determined.