Membranes and Integrated Membrane Operations as Clean Technologies in the Leather Industry

Abstract

The leather industry is characterized by the production of a huge amount of wastewater with a high organic/inorganic charge, causing widespread water and soil pollution. Pressure-driven membrane operations and membrane bioreactors have long been proven to be a valid approach for the treatment of tanning wastewaters aimed at the recovery of raw materials as well as for the removal of toxic and environmentally harmful substances. Such processes, opportunely integrated among themselves and/or with conventional physical-chemical and biological treatments, also provide useful protocols for the treatment of global wastewaters with significant advantages in terms of environmental protection, decrease of disposal costs, simplification of cleaning-up processes and saving of water and chemicals. This paper, as the state of the art, attempts to revise the potential and perspectives of membrane-based technologies in the leather industry with related applications in beamhouse, tanning and post-tanning operations as well as in the treatment of global wastewaters.

Valorisation of Tannery Waste to Recover Chromium with a View to Reusing It in Industrial Practise

“…The aim of using the UF process was to separate organic compounds from the alkaline hydrolysate. This process was selected based on literature data [ 18 , 19 ], according to which it can be successfully used for the preliminary treatment of tannery wastewater. During the UF process of alkaline hydrolysates, partial separation of chromium was observed ( Figure 3 ).…”

“…Similar results were obtained by Khan et al [ 26 ] during tanned hides by chromium recovered from spent tanning baths by the precipitation process. Drioli et al [ 18 ] proposed the regeneration of the chromium spent tanning bath with an integrated UF/NF system. The waste chrome liquor treatment method using solar evaporation also shows promise as a practical solution for valorisation [ 27 ].…”

“…The waste chrome liquor treatment method using solar evaporation also shows promise as a practical solution for valorisation [ 27 ]. The results of research and literature data [ 18 , 26 , 27 ] imply that the recovered chrome can be seamlessly incorporated into subsequent tanning processes without compromising the economic value of the resulting leather. Considering this, it is expected that the tanneries will be interested in a circular economy setup chrome recovery plant to ensure a protected environment and a profitable chrome tanning process.…”

Composite Anion Exchange Membranes Based on Quaternary Ammonium-Functionalized Polystyrene and Cerium(IV) Phosphate with Improved Monovalent-Ion Selectivity and Antifouling Properties

“…Therefore, wastewater treatment, often using membrane technologies, including electrodialysis, has been the focus of attention in recent years [ 7 , 8 , 9 , 10 ]. Meanwhile, many deposits are being depleted; therefore, the content of some elements in natural sources becomes comparable with that in industrial and municipal sewage [ 11 , 12 , 13 ]. From this standpoint, a promise is held by technologies that imply waste recycling, in particular, on-site recycling of water or other solvents to the production process after purification and extraction of valuable components (so-called zero liquid discharge technologies) [ 14 ].…”