Abstract

It is acknowledged that within the chemical processing of hides into chrome-tanned leather that the liming, acid pickle and the tanning processes are the major contributors of pollutants. This is in terms of biological load, suspended solids, sulfide, nitrogen, chromium, salinity and the resultant sludges for disposal.

This loading includes unused chemicals that are discharged from these processes due to their poor process efficiencies. Many attempts have been made to lessen this waste at source, but technologies in common use have basically remained unchanged for decades.

Solutions to these problems are far reaching, and the details set down in this paper describe a technology that addresses and resolves these matters. This information was compiled through independent on-site studies within three major tanneries, where approximately 60 000 wet-salted US, European and Australian hides per week have been processed since 2013. Accordingly, this paper describes in detail this radical new approach to leather manufacture.

The initial investigations and developments of this technology by BIOSK involved the building of a full scale wet-blue manufacturing plant, and five years of developments before introduction to industry. The practicality and value of this technology has since been verified by continuous full scale manufacture by tanners that commenced in 2011.

The technology involves the complete retention and recycling of used floats from liming, pickle and tanning in self-contained loops, and eliminates associated washing cycles. This is the base for the complete uptake of processing chemicals, a significant reduction in water use, and zero effluent discharged from these critical manufacturing stages.