Pre-treatments aimed at increasing the biodegradability of cosmetic industrial waste

This work investigated physic-chemical pre-treatments aimed at improving anaerobic digestion (AD) of cosmetic industrial waste produced by a plant belonging to L'Oreal Group. A mixture designed according to relative abundances of waste was considered: sludge from internal wastewater treatment plant (54%-wt), residues of shampoo/conditioner (31%-wt), mascara sludge (13%-wt), food waste (2%-wt). The mixture had 80% VS/TS and COD equal to 1240 mg O-2/gvs; soluble fraction of COD was 22%. Investigated pre-treatments were: chemical, thermal, sonication and various combinations; their performances were assessed through the disintegration rate (DR, the increment of soluble COD due to the pre-treatment compared to the unaltered sample). Best results were achieved from TA- thermo-alkaline (120 min at 50 degrees C) with DR 64.4% and TAS - thermo-alkaline-sonication (15 min at 80 degrees C and 40 kHz) with DR 66.1%. The benefits of AD on pre-treated waste mixture were: 50% increase in methane yield (0.14 Nm(3)/kgvs) and 5-7%-wt reduction of waste amount. From technical, energy and economic viewpoints, the proposed technical solution can provide an interesting perspective, fully consistent with Circular Economy principles. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.