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A greener and eco-friendly method to leather tanning process has been developed in the present investigation, which is based on d-Lysine aldehyde complex. This can be considered as a substitute for chrome-free tanning process. The physico-chemical and morphological characteristics, resistance to collagenolytic activity and organoleptic properties of the d-Lysine glutaraldehyde tanned leather were evaluated in terms of environmental impact assessment. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. It has been shown that the above properties of the tanned leather are better than that of glutaraldehyde alone or equal to chrome tanned leather. The density of the fibre structure throughout the cross section indicates the even structure and fibre bundles seem to be less dispersed compared to glutaraldehyde alone; were analysed by using scanning electron microscopic and atomic force microscopic techniques. This tanning tanned leather demonstrated a higher resistance to collagenolytic activity than conventional tanned leather. The tanned leather exhibited good fullness, softness, smoothness, colour and general appearance compared to glutaraldehyde alone. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional tanning method is evident from environmental impact assessment studies. This tanning process has the cost advantages due to the possible decrease in chemicals consumptions and net saving from the reduced effluent treatment costs. The improved tanning process reduces generation of toxic waste compared to chrome tanning process and can be regarded as eco-friendly, which reducing the environmental impacts and contributes to the development of greener or cleaner process.

The environmental impact of the tanning industry is generally significant with outputs of wastes, i.e. high concentrations of organics, salts and heavy metals (chromium compounds), both in solid and liquid form, as a result. In order to bring the tanning industry more in line with present environmental thinking, various methods have been devised to reduce impacts. The underlying study proposes a modification of the method for unhairing–liming of hides where the unhairing–liming liquids are reused several times after being recharged by reduced quantities of chemicals. The study, therefore, aims at reducing both the economic and environmental costs of the unhairing–liming process. Experiments were carried out at lab scale with a simulation apparatus designed for the purpose. Life cycle assessment was used to evaluate the net environmental benefits of the modified method. The present value approach was used to evaluate the economic feasibility of the modified method. The quality of the produced leather was assessed by experts from the tanning sector (tanners). On the environmental level, the modified method reduced the environmental impact of the process by 24%, COD was reduced by 50% as well as sulfide which was reduced by 73% when the process water was recycled four times. The modified method requires some investment in new equipment and is a little more labor intensive as compared with the conventional method but does permit for savings in water up to 58% and chemicals up to 28% as well as wastewater treatment cost which was reduced by 58%. The modified method allowed for four times reuse of the unhairing–liming liquor without visibly affecting the quality of the final product of leather. It was concluded that both the economic and the environmental costs of the unhairing–liming process were reduced relative to the same of the conventional method.

This article discusses the need to integrate scientific research with the concept of Industrial Ecology, acting as support for the development of Eco-technologies. In order to proceed with the discussion, an initial section presents the concepts. A new and more accurate position concerning the extension of Eco-technologies in the context of Industrial Ecology is proposed. Emphasis on the role of academic scientific research as a way to propose and support specific solutions for local problems. Thus, alternative solutions based on the application of non-conventional technologies, which explore the unique regional characteristics of a Brazilian region, are examined. The sharing of waste streams generated by two polluting industries, mining and leather tanning, can lead to lower environmental impact if compared with separate management of their wastes. A comprehensive bibliographic review of non-conventional technologies related to heavy metal attenuation is included.