Search Results (38)

Leather biodegradation is a complex microbial process with increasing relevance for sustainable waste management. In this study, we investigated bacterial communities responsible for the degradation of leather treated with different tanning agents (chrome, Zeolite, Biole^®) using high-throughput 16S rRNA gene sequencing and metatranscriptomic analysis. Proteobacteria, Bacteroidetes, and Patescibacteria emerged as the dominant phyla, while genera such as Acinetobacter, Pseudomonas, and Sphingopyxis were identified as key contributors to enzymatic activity and potential metal resistance. A total of 1302 enzymes were expressed across all the conditions, including 46 proteases, with endopeptidase La, endopeptidase Clp, and methionyl aminopeptidase being the most abundant. Collagen samples exhibited the highest functional diversity and total enzyme expression, whereas chrome-treated samples showed elevated protease activity, indicating selective pressure from heavy metals. Differential enzyme expression patterns were linked to both the microbial identity and tanning chemistry, revealing genus- and treatment-specific enzymatic signatures. These findings deepen our understanding of how tanning agents modulate the microbial structure and function and identify proteases with potential applications in the bioremediation and eco-innovation of leather waste processing. Full article

The leather tanning industry generates a substantial quantity of solid waste, which, in part, is discarded in the environment in landfills or incinerated. One alternative end-of-life solution is to manufacture engineered materials by forming composites with a thermoplastic polymer/binder. In this work, leather fibres (LFs) were melt-compounded into partially bio-based thermoplastic polyurethane (TPU), at leather fibre contents between 10 and 30% (TPU/LF), followed by compression moulding or 3D printing. The results showed that the incorporation of LF into the polymer matrix produced materials with a Young’s modulus comparable to that of leather. The melt extrusion processing influenced the polymer chain orientation and the resulting mechanical performance. The cyclic stress softening and abrasion resistance of the TPU/LF materials were evaluated to understand the potential of this material to be used in the footwear industry. The level of LF incorporation could be tailored to produce the specific targeted mechanical properties. This work demonstrates that LF could be used to produce materials with a high potential to be used in the fashion industry. Full article

Following the concept of “waste into resources”, a mild and controllable light grafting technique was used to immobilize pancreatic lipase (PPL) in situ on modified organic, chromium-free tanned leather scraps to catalyze the hydrolysis of waste oil. The experimental results showed that immobilized PPL significantly improved the catalytic activity, operational stability, reusability, and storage stability compared to free PPL. Furthermore, the study evaluated the environmental compatibility of the system through biological risk assessment of soil extracts after degradation, indicating that the system has good environmental compatibility. The experiment is simple to operate, uses mild conditions, and the immobilized material is obtained from leather-making solid waste. The use of this immobilization system to treat waste oil in the leather-making process is of great significance for achieving clean and sustainable production in the leather industry. Full article

The substantial waste generated during the processing of hides and skins as well as at other stages of manufacturing is a recurring issue in the leather industry that this article attempts to address. To investigate the mechanical and thermal characteristics of the resultant composites, this study suggests using leather waste from the bovine leather industry, analyzes the tanning process, and assesses the viability of mixing this waste with natural rubber (TSR-20). Without the inclusion of leather waste, the resulting composites had exceptional tensile strength, surpassing 100% of rubber’s strength. The effective interaction of the recycled leather particles with the natural rubber matrix was evidenced using the Lorentz–Park equation. This better performance points to a competitive relationship between rubber and leather waste. The samples’ density was 10% greater than that of polybutadiene elastomers and 10% greater than that of natural leather, while the hardness was comparable to that of PVC, which is frequently utilized in the design of general-purpose soles. This suggests that waste from the leather industry can be efficiently utilized in sustainable applications, particularly in the production of leather goods and shoes, helping to valorize waste that is typically discarded. Furthermore, by encouraging the use of recycled resources in the creation of new compounds, this plan provides the rubber sector with a sustainable option. To optimize this proposal, perhaps will be necessary to identify different vulcanization systems to improve the physical mechanical properties and other uses derived from the optimizations realized. This composite can be applied in the fashion industry in order to develop new trends around the application of waste and residues for a natural design line. Through the research process, it was possible to integrate the residues into the natural rubber matrix, as evidenced in the characterization process. Full article

The leather industry generates significant amounts of waste, including chromium-tanned leather waste (CTLW), which poses environmental and health hazards due to chromium’s potential toxicity. Efficient management of CTLW is crucial for environmental sustainability and resource recovery. Various methods exist for chromium recovery, including physical, chemical, and biological processes, with chemical methods, particularly substitution extraction using organic acids, showing promising results. This study investigates the use of organic acids for the substitution extraction of chromium from CTLS, with a focus on safety by monitoring the concentration of toxic chromium (VI). It was found that oxalic acid (OA) at a temperature of 43.6 °C and a concentration of 1.34% achieved an extraction efficiency of 63.1% while maintaining minimal hydrolysis at 0.70%. This method offers a sustainable and environmentally friendly approach to chromium extraction from CTLW, addressing a critical need in waste management practices. Full article

Leather waste contains up to 10% nitrogen (N); thus, combustion or gasification only for the energy recovery would not be rational, if safety standards are met. On the other hand, the chromium (Cr) content exceeding 5% in half of the waste stream (w/w) is too significant to be applied in agriculture. In this work, four acid hydrolysates from leather waste shavings, both wet-white free of Cr and wet-blue with Cr, were used: two with a mixture of acids and supplemented with Cu, Mn, and Zn, and the other two as semi-products from collagen extraction using hydrochloric acid. Additionally wet-green leather waste shavings, e.g., impregnated with olive extract, were used followed by the two treatments: amendment with a biochar from “wet white” leather waste shavings and amendment with this biochar incubated with the commercial phosphorus stimulating microbial consortia BactoFos. They were applied as organic nitrogen-based fertilizers in a glasshouse experiment, consisting of 4–5 subsequent harvests every 30 days, under spring–autumn conditions in northern Poland. Biochar-amended wet-greens provided the highest nitrogen use efficiencies, exceeding 100% after 4 months of growth (for 20 kg N/ha) and varying from 17% to 37% in particular months. This is backed up by another parameter (relative agronomic effectiveness) that for these materials exceeded 150% for a single month and in total was around 33%. Biochar amendments significantly increased agronomic parameters for wet-greens, and their microbial treatment enhanced them even further. Recycling this type of waste can replace inorganic fertilizers, reducing greenhouse gas emissions and carbon footprint. Full article

Chromium is an essential element in various industrial processes, including stainless steel production, electroplating, metal finishing, leather tanning, photography, and textile manufacturing. However, it is also a well-documented contaminant of aquatic systems and agricultural land, posing significant economic and health challenges. The hexavalent form of chromium [Cr(VI)] is particularly toxic and carcinogenic, linked to severe health issues such as cancer, kidney disorders, liver failure, and environmental biomagnification. Due to the high risks associated with chromium contamination in potable water, researchers have focused on developing effective removal strategies. Among these strategies, biosorption has emerged as a promising, cost-effective, and energy-efficient method for eliminating toxic metals, especially chromium. This process utilizes agricultural waste, plants, algae, bacteria, fungi, and other biomass as adsorbents, demonstrating substantial potential for the remediation of heavy metals from contaminated environments at minimal cost. This review paper provides a comprehensive analysis of various strategies, materials, and mechanisms involved in the bioremediation of chromium, along with their commercial viability. It also highlights the advantages of biosorption over traditional chemical and physical methods, offering a thorough understanding of its applications and effectiveness. Full article

In the context of climate policy, measures are being taken around the world to reduce pollution. These have been intensified in the areas of transport, industry, and energy, with the goal of zero emissions. The role of the biogas plant in energy transition and as a waste treatment plant for disposal is very important. This article describes research on a dynamic anaerobic digestion (AD) process plant. The subject of this study was leather shavings, which is a problematic waste. The research presented here is intended to demonstrate the decomposition of the flesh in the process, to confirm its biogas yield, and to evaluate the biological and technical parameters of the process. High biochemical stability was achieved for each of the tests evaluated, and no specific technical requirements were demonstrated. The only technical aspect to be addressed during operation was sedimentation, which can be solved by preparing the mixture earlier or by changing the mixing method. This made it reasonable to investigate the material further in the context of an industrial project. The characteristics of protein degradation in the AD process resulted in a high methane content in the biogas, above 65%. It was also observed that the long conditioning time of biogas in the gas cushion favourably affected the proportion of methane in biogas. Analytical results confirmed 77.5% methane content, which was a very good result. This paper presents the results of a surprising effect of chromium, primarily Cr (III), on the performance of anaerobic digestion. Full article

The leather industry is one of the most polluting industries in the world due to the large amounts of waste following raw hide processing but also due to the high content of chemical substances present in leather waste. The main problem with chromium-tanned leather solid waste is related to the storage, due to the ability of chromium to leach into soil or water, and also owing to the high ability of trivalent chromium to oxidize to its toxic form, hexavalent chromium. The purpose of this article is to present the most current methods of chromium extraction from solid tanned leather waste in order to obtain non-polluting leather, which can constitute secondary raw material in new industrial processes. The extraction methods identified in the present study are based on acid/basic/enzymatic hydrolysis and substitution with the help of organic chelators (organic acids and organic acid salts). In addition, this study includes a comparative analysis of the advantages and disadvantages of each identified extraction method. At the same time, this study also presents alternative chromium extraction methods based on the combination of conventional extraction methods and ultrasound-assisted extraction. Full article

Tanning, crucial for leather production, relies heavily on chromium yet poses risks due to chromium’s oxidative conversion, leading to significant wastewater and solid waste generation. Physico-chemical methods are typically used for heavy metal removal, but they have drawbacks, prompting interest in eco-friendly biological remediation techniques like biosorption, bioaccumulation, and biotransformation. The EU Directive (2018/850) mandates alternatives to landfilling or incineration for industrial textile waste management, highlighting the importance of environmentally conscious practices for leather products’ end-of-life management, with composting being the most researched and viable option. This study aimed to isolate microorganisms from tannery wastewater and identify those responsible for different types of tanned leather biodegradation. Bacterial shifts during leather biodegradation were observed using a leather biodegradation assay (ISO 20136) with tannery and municipal wastewater as the inoculum. Over 10,000 bacterial species were identified in all analysed samples, with 7 bacterial strains isolated from tannery wastewaters. Identification of bacterial genera like Acinetobacter, Brevundimonas, and Mycolicibacterium provides insights into potential microbial candidates for enhancing leather biodegradability, wastewater treatment, and heavy metal bioremediation in industrial applications. Full article

The leather and footwear cluster in Tungurahua state has a main role in the country’s production chain, supplying 76% of the country’s tanned hides for the textile, footwear, and furniture industries, among others. The processes involved in leather tanning generate liquid, gaseous, and solid waste, the latter including the shavings from the leather trimming process, which, due to their composition and volume, are compressed and disposed of in sanitary landfills. Through Strategic Design and circular processes, as axes of change in production, new processes and strategies are established for the creation of products derived from the reuse of tannery waste; as a result, a decorative block is obtained for the design of architectural spaces with dimensions of 150 × 75 × 355 mm, 300 g in weight, and a compressive strength of 15.72 MPa. This is subjected to physicochemical tests for its validation. Full article

Chrome tanned leather shavings (CTLS) are considered one of the more difficult wastes to manage in the tanning industry. At the same time, this waste is an important source of good quality collagen. The few methods described in the literature for the valorization of these wastes usually require pre-treatment or activation. In this study, an attempt was made to see if raw chrome tanned leather shavings (CTLS) could be modified to obtain secondary raw materials with new physical properties. Glutaraldehyde, glycerol, EDCs, pectin, and tannins were selected for modification of the CTLS. The effectiveness of the processes carried out was confirmed by FTIR analysis of the materials obtained. Changes in the intensity of the characteristic collagen peak (amide I, amide II, and amide III) and changes in the position of the bands in the 1200–1000 cm⁻¹ region were observed in the recorded spectra. The modifications introduced confirmed changes in the physical properties of samples M1–M5, including an increase in bulk density from 0.15 to 0.59 g cm⁻³, and improved tensile strength is some cases. The elemental content results of the samples tested showed the resulting modified CTLS were free of Cd, Hg, Pb, and Cr(VI). It was also confirmed tanning waste contained significant amounts of various valuable elements. The research also included preliminary tests to assess the environmental impact of the modified materials. In a phytotoxicity test conducted on modified CTLS, M1 with pectins showed the highest root stimulation (105%), while samples with glutaraldehyde and unmodified CTLS showed significant root inhibition (75%, 74%). Other samples showed moderate plant toxicity and seed germination was not significantly affected. Full article

The centralized Rio Seco Industrial Park (RSIP) tannery collective in the Southern Peruvian city of Arequipa releases untreated tannery wastewater into a proximal creek that is a tributary of the Chili River. As industrial leather tanning wastewater contains high concentrations of metal(loid)s, salts, dyes, and organics, this complex mixture could exert a myriad of toxicological effects on the surrounding ecosystem. The RSIP effluent was analyzed to quantify the acute ecotoxicity and ecotoxicological status of this untreated industrial wastewater at multiple trophic levels with the following bioindicators: the floating macrophyte Lemna minor, invertebrates Daphnia magna and Physa venustula, and the amphibian Xenopus laevis. A physicochemical characterization of the RSIP effluent revealed a highly contaminated waste stream. In addition to chromium (10.4 ± 0.4 mg/L) and other toxic metals, the water harbored extremely high concentrations of total dissolved solids (67,770 ± 15,600 mg/L), biochemical oxygen demand (1530 ± 290 mg/L) and total nitrogen (490 ± 10 mg/L). The toxicological responses of certain bioindicator species tested were evaluated after exposure to 0, 1.5, 3.0, and 4.5% untreated tannery wastewater blended with dechlorinated tap water. L. minor experienced a significant decrease in the number of fronds, wet weight, and dry weight at the lowest blended wastewater of 1.5%. Bioassays with D. magna showed the effect on neonatal mortality with a calculated LC₅₀ of 1.1% for 48 h. Bioassays with P. venustula embryos showed high sensitivity to diluted effluent with complete mortality at 3.0% wastewater and above. Finally, X. laevis showed a high sensitivity to the dilutions with an LC₅₀ of 1.6 for embryos and 1.8% for tadpoles. Although RSIP wastewater contains many potentially toxic components, chromium and total dissolved solids, with a major contribution from sodium, are best correlated with acute toxicity variables. This suggests that conductivity or analogous measurements could provide a rapid and affordable forensic tool to query acute ecosystem pressures. Collectively, the results indicate that the release of untreated tannery wastewater from RSIP can exert pronounced acute impacts across trophic levels with the need for treatment or dilution to below 1% of total flow. As the assays addressed acute toxicity, the necessary treatment and/or dilution to mitigate chronic effects is likely much lower. In conclusion, untreated RSIP tannery wastewaters represent an ecological risk to downstream aquatic ecosystems; this needs to be addressed to prevent current and future environmental consequences. Full article

This review delves into the processing of tannery solid waste, emphasizing fleshings and chromium-tanned leather waste. This paper centers on fat recovery, chromium elimination, and protein preservation, aiming to make them apt for animal consumption. This paper also assesses the potential of introducing such recycled products to the global market. Drawing on the literature from the past two decades, sourced comprehensively from Scopus and Web of Science, 36 articles were selected because of their significant contributions from leather production powerhouses such as India and Brazil. Fleshings have shown immense potential as animal feed, and the extraction of tallow and collagen from rawhide trimmings yields up to 98% and 93%, respectively. Fermented tannery fleshings, notably with Enterococcus faecium HAB01, also demonstrate strong antioxidant capabilities. The overarching consensus emphasizes the need for rigorous purification when dealing with chromium-containing wastes, addressing concerns tied to Cr (III) and Cr (VI). Furthermore, raw tannery fleshings stand out as a sustainable, cost-effective, and globally marketable solution for animal feed production. Full article

Due to the variety of benefits over traditional cutting techniques, the usage of laser cutting technology has risen substantially in recent years. The attributes of laser technology for leather cutting include adaptability, mass production, capability of cutting complicated patterns, ease of producing tailored components, and reduction in leather waste. In the present study, vegetable chrome-tanned buffalo leather specimens were cut using a 20 W laser diode with conventional and pulse width control in a photodiode-assisted laser cutting process. Emission rate, kerf width, carbonization, and material removal rate were considered as quality indicators. The higher power density associated with the pulse width approach reduces the interaction with the specimen, which results in a better emission rate and material removal rate, along with a lesser kerf width and carbonization. Using the MOORA approach, the optimal parameters of the present study were found to be a stand-off distance of 22 mm, a feed rate of 200 mm/min, a duty cycle of 75%, and a frequency of 20 kHz. The duty cycle can effectively control the pulse width at which the energy has been dissipated across the cutting zone. Full article