ANAEROBIC BIODEGRADABILITY OF PRINT PASTES PLUS PRIMARY SEWAGE-SLUDGE

The object of this research was to investigate the behaviour of the co -digestion of print pastes and primary sludge at lab-scale, in view of a possible full-scale application of this process. The research was f ocused upon the following aspects: performance and reliability of the co-digestion process, possible interference with the sludge stabilisat ion (which remained the first aim of the digestion), disappearance of the colour clue to the pastes, composition of the supernatant to be se nt back to the aerobic wastewater process. Three print pastes were use d. Inhibition of the anaerobic process was found during the first peri od. After approximately 70 days of acclimation, the reactors operated regularly, with satisfactory performance. However; print pastes, that accounted for 10% of the total influent CODs were not biodegraded to a large extent. Absorbance in the visible spectra of the supernatants w as modified and/or reduced with respect to the influent, depending on the dyes present in the paste. (C) 1998 Published by Elsevier Science Ltd.