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Sodium chloride (NaCl) is commonly used as a curing/preservative agent for raw hides and skins in tanneries and is removed through a soaking process with total dissolved solids (TDS) and other organic pollutants in effluent, causing significant pollution load to the environment. Hence, the present study evaluated to apply dried neem leaf powder (DNL) as an additive to reduce the usage of salt in skin processing and preservation. To make certain of DNL antimicrobial properties, solvent extracts were performed against proteolytic bacteria isolated from raw skins. Initial characterization of DNL revealed the presence of bioactive compounds nimbolide and dehydro salannol and acetone extract with 16.9-mm, 10-mm and 8-mm zone of inhibition against Salmonella sp., E. coli sp. and Bacillus sp. identified using phenotypic conventional biochemical screening method. Further, skin curing experiments were carried out using four different treatments of DNL (10% 15%, 20% and 25% w/w) along with 15% w/w of conventional salt to obtain an optimum concentration for pilot-scale studies. Thus, the application of optimal DNL (15%) and salt (15%) resulted in no physical changes such as smell and hair slip and was taken for further studies for hydroxyproline activity, pollution load and organoleptic properties along compared with control 40% salt. DNL-aided salt less preservation of freshly flayed goat skins at ambient condition showed no hair slip or putrefaction during the preservation period with significant reduction of TDS (86%) and chloride (71%) in soak liquors compared to conventional salt preservation and enhanced organic load requiring additional treatment. However, the application of the organoleptic, physical and hydrothermal properties of resulting leathers produced from the DNL applied skins was on par with results of leather obtained from conventional salt. Thus, our results demonstrate DNL-aided salt less preservation method is able to reduce the amount of salt for preservation of goat skins significantly, leading to reduced salinity issues during leather processing.

BACKGROUND In March 2014, the European Commission issued a new regulation restricting the content of hexavalent chromium (Cr) in leather to no more than 3 mg/kg. We previously performed a questionnaire study in January 2014 to characterize our patients with Cr contact allergy prior to regulatory intervention. OBJECTIVES To assess whether clinical characteristics, self-reported sources of Cr exposure, and burden of disease changed in patients with Cr allergy over time. METHODS A questionnaire study was performed among 172 adult dermatitis patients with Cr allergy and 587 age- and sex-matched dermatitis patients without Cr allergy. A questionnaire was sent to all dermatitis patients patch tested from 2003 to 2018 in August 2019. RESULTS The overall response rate was 61.2% (759/1241). Patients with Cr allergy were still more commonly affected by current foot dermatitis (odds ratio [OR] 3.82, 95% confidence interval [CI] 2.07-7.08) and hand dermatitis (OR 1.98, 95% CI 1.13-3.49) compared with controls diagnosed during 2013 to 2018. The proportion of patients with Cr allergy reporting dermatitis caused by leather exposure did not change during 2003 to 2012 vs 2013 to 2018 (71.0% vs 66.2%, P = .5). Furthermore, estimates on occupational performance and disease severity (eg, current dermatitis), number of anatomical locations with dermatitis, worst-case dermatitis, and effect on work were similar in patients with Cr allergy for 2003 to 2012 vs 2013 to 2018. CONCLUSION No immediate sign of improvement was found in patients with Cr allergy concerning severity of disease and dermatitis from leather exposures 5 years after adoption of the regulation against hexavalent Cr in leather. The regulation may have to be revised for better protection of those already sensitized.

The removal of anionic and cationic dyes from aqueous solutions was investigated by different leather shavings, which are solid wastes generated in the leather industry. Wet-blue leather shavings (WB), vegetable-tanned leather shavings (VT), pickled hide (not tanned) shavings (PIC) and wet-white leather (pre-tanned) shavings (WW) were used. The cationic dye was Basic Red 2 and the anionic dye was Acid Brown 414. Point of zero charge, functional groups, shrinkage temperature and adsorbent surface area were characterized. The point of zero charge was 4.0, 6.0, 3.9 and 4.1 for WB, VT, PIC and WW, respectively. The specific surface area showed low values which was expected for this type of material. Tanning agent influence was verified through shrinkage temperature analysis of leather shavings. Main functional groups of the acid dye and the collagen structure of the solid wastes were determined. The tests with Basic Red 2 solutions showed only VT had a considerable removal for this cationic dye (96.7%). The tests with Acid Brown 414 were carried out with different contact times and adsorbent mass. Results showed high efficiency of WW and PIC, whose percentages of dye removal were above 96% at contact time of 30 min and above 90% using 20 mg of adsorbent. In this way, the final dye removal was 98.1% and 98.3% for contact time tests and 97.7% and 98% for adsorbent mass tests for WW and PIC, respectively. These results highlight the promising use of leather shavings as alternative adsorbents for the treatment of wastewater containing dyes.

Leather manufacturing involves a number of unit processes, out of which tanning is the most important in so far as it converts the putrescible hides/skins into non-putrescible leather. In this study, glutaraldehyde has been exploited as a means to reduce the use of basic chromium sulfate for the production of quality shoe upper crust leather. The paper consists in studying the physical properties of aldehyde-tanned leather and chrome-tanned leather. The aim is to find out the possibility of replacing the wet-blue leather, containing Cr(III) salts, with the glutaraldehyde-tanned wet-white leather. The physical properties of the aldehyde-tanned leather were evaluated, analyzed and compared with the conventional chrome-tanned shoe upper crust leather. Statistical analysis illustrated that the tensile strength, the percentage of elongation, stitch tear strength, Baumann tear strength and grain crack strength of the leather was 211±1 kg/cm2, 38±0.5 %, 89±0.11 kg/cm, 63±0.4 kg/cm and 23±0.4 kg respectively. It was observed that the property of the experimental leather was quite comparable with the conventional chrome-tanned leather and able to meet the requirements of the shoe upper crust leather after re-tanning. The shrinkage temperature of the experimental tanned leather was found to be 87 °C,lower than that of corresponding control, which indicates lesser tanning power of aldehyde. However, the morphology of the aldehyde-tanned leather was quite akin with the conventional leather. This study suggests that using glutaraldehyde in the tanning process in order to minimize the chromium load in the tanning and the re-tanning process during the production of shoe upper crust leather reduces the generation of toxic waste and its impact on the environment.

Industrial activities that consume water generate wastewater as a by-product of processing which introduces various contaminants such as heavy metals into the neighbouring water bodies that creates adverse effects on the surrounding environment. Tannery industry releases more toxic effluent than most industries, which directly and indirectly exerts stress on various ecosystems. The heavy metal chromium (Cr), one of the pollutants found in tannery effluent, is very much detrimental to human health, animals, and plants. Conventional physico-chemical and biological processes can remove this heavy metal in considerable amounts. Recently, various applications of advanced technologies such as membrane technology, electrocoagulation, ion exchange, and electrodialysis for tannery wastewater have been growing due to their relative advantages over other technologies in terms of sustainability. This paper represents the review of various available techniques as well as represents a case study of chromium removal from tannery effluent by a low-cost absorbent.

Pelt obtained by deliming with peracetic acid can be chromed after additional treatment with sodium chloride or oxalic acid solution, or directly tanned using synthetic tannins. The results of differential scanning calorimetry and thermogravimetric analyses have suggested that any tanning increases thermal stability of leather collagen. The produced chrome-free leather, despite its high tensile strength, is not characterized by high shrinkage temperature what indicates insufficient thermal stability of such leather. This fact contradicts the results of differential scanning calorimetry and thermogravimetric analyses results which show the high thermal stability of the chrome-free leather. It has been concluded that scanning calorimetry and thermogravimetric analyses are not sufficient for the appropriate assessment of leather obtained by the methods of various tanning, and the conclusions about changes in leather structure and quality of leather can not be drawn only upon results of the mentioned analyses.

Accumulation of hair waste is a major burden to the leather industry, causing a negative impact on the industry's sustainable development. The industry is already bogged down by the usage of synthetic re-tanning agents that are not only extremely challenging for biodegradation but also release free-form of formaldehyde in the final leather stage. This research work focuses on developing a formaldehyde-free bio-based re-tanning agent from hair waste. In order to do so, hair waste is subjected to alkali hydrolysis and subsequently graft-copolymerized with methacrylic acid (MAA). These treatments were optimal using 20 % (w/w) sodium hydroxide and thermal activity at 90 °C. This resulted in effective hydrolysis of red sheep hair, which was the ideal candidate in this study. The hydrolysate was subjected to monomer in situ polymerization (using MAA) with potassium per sulfate/sodium meta-bisulphite redox system, leading to the development of keratin hydrolysate-g-methacrylic acid (KH-g-MA) copolymer (this was noted both at a laboratory level and pilot scale). The obtained KH-g-MA copolymer exhibited ideal characteristics such as increased protein content (78.3 ± 1.2), appropriate particle size (1516 nm), suitable pH (5) and required viscosity of 512 cP. The developed KH-g-MA copolymer was then applied as a re-tanning agent in the leather manufacturing process. Significant improvement in leather's mechanical strength characteristics was observed. In addition, the organoleptic properties of leather such as fullness, softness and grain tightness showed much improvement. Scanning electron microscopy (SEM) showed an enhanced surface smoothness and filling of the voids in experimental leather in comparison to the control leather. This recycle and reuse strategy of hair waste not only helps resolve issues with handling of hair solid waste but also results in producing an eco-friendly re-tanning agent in leather manufacturing, thereby paving the way for cyclic economic utilization and cleaner environment.

The utilization of biotechnology in leather sector has more extensive in modern years; more particular to proteolytic enzymes and employed in several steps of the leather making such as soaking, dehairing, bating, solid waste management etc. The current study evaluates the performance of alkaline protease from Bacillus crolab MTCC 5468 in single soaking of goat skins matrix by comparing with the conventional multiple soaking processes. According to the obtained results, the optimum concentration for maximum rehydration of goat skins was accomplished at 1.0% (v/w) of alkaline protease at duration of 3 h over traditional rehydration method (4–6 h). The moisture level, total protein, chloride content and total organic carbon of enzymatic rehydration was superior to that of conventional rehydration and it was also used to measure the effectiveness of rehydration process. Scanning electron microscopic images of enzymatically processed leather exhibits enhanced opening of fiber bundles and smooth grain surface than conventional method. Furthermore, the alkaline protease treated leather exhibited improved moisture uptake, removal of chlorides and suppleness because of hydrolysis of non-collagenous proteins as indicated by well opened up fiber bundles in histological analysis. The application of alkaline protease in rehydration operation of leather production confirmed scope for diminishing water quantity around 66.6%, soaking duration at 50%, minimizing use of harmful dehairing chemicals at 50–60%, thereby, eliminating the bating operation during pre-tanning. These outcomes suggest that alkaline protease have potential application in rehydration of skins for immense environmental concerns of leather tanning sectors.

Cr(VI) tolerance in Aspergillus flavus, strain SFL, isolated from tannery effluent was measured and compared with a reference strain of A. flavus, A1120. On solid medium, SFL had a high level of Cr(VI) tolerance (1,600 mg/L), which was 16 times that of A1120 and greater than most previously analyzed fungal strains. When in 100 mg/L of Cr(VI), SFL completely depleted Cr(VI) within 72 h while A1120 depleted 85% of Cr(VI). SFL was more effective in reducing extracellular Cr(VI) than A1120. While A1120 showed greater biosorption of Cr(VI) than SFL, intracellular accumulation was approximately 50% greater in SFL and was more energy-dependent than A1120. Cr(VI) modified the external surface of the hyphae. Cr speciation detected the presence of only Cr(III), corresponding to Cr(OH)3 , which precipitated on the hyphal surface. Cr(VI) bound to the functional groups carboxyl, amine, and hydroxyl in both SFL and A1120. Transmission electron microscopy energy-dispersive X-ray detected Cr on the fungal wall and within membrane-bound organelles of the cytoplasm. In conclusion, the greater tolerance of SFL to Cr(VI) relative to A1120 is due to more effective energy-dependant uptake of Cr(VI) into the cell and increased capacity of SFL to store Cr in intracellular vacuoles compared with A1120.

The ability of Aspergillus Niger strain to reduce organic and mineral pollution as well as the toxicity of two tannery wastewaters, the unhairing effluent (UE) and the final effluent (FE), taken from a local Tunisian tannery and under nonsterile conditions, was studied. Raw effluents show alkaline pH ?11; thus experiments were carried out at initial pH values and at pH adjusted to 6. Characterization of effluents also revealed high salt levels (EC > 17 mS/cm) and high organic matter content (25 g/L for the UE and 7.2 g/L for the FE) but a low biodegradability since BOD5 did not exceed 2.5 and 1.25 g/L for the UE and the FE, respectively. The results of the biological treatment showed that A. Niger was able not only to grow at high pH and salinity values, but also to reduce organic and mineral pollutant load. After treatment, the COD reduction for the UE reached 90% and 70% at pH=6 and at initial pH (12.13), respectively. For the FE, the decrease of COD values reached 75% at pH=6 and 64% at initial pH (11.64). Monitoring of mineral pollution levels showed a reduction in chromium (Cr) concentrations reaching 70% for the FE. This was reflected by an increase of the biomass of A. Niger from 9.25 g/L (control) to 9.84 g/L for the FE. To confirm the efficiency of the biological treatment using A. Niger, phytotoxicity (tomato seeds) and microtoxicity (Escherichia coli and Bacillus subtilis) tests were carried out. Results of this monitoring showed an important decrease in the toxicity levels for both effluents. - 2019 Raouia Boujelben et al. The present research study was supported by the Ministry of Higher Education and Scientific Research-Tunisia under Research Contract Program of the Environmental Bioprocesses Laboratory. The authors thank Mr. Slim LOUKIL and Mr. Nidhal BACCAR for their technical assistance. Scopus

Resumen En este estudio se evaluó la remoción de sulfuros en aguas residuales del proceso de pelambre o depilado de pieles, utilizando ozono como agente oxidante. Se determinó el efecto del pH inicial sobre el proceso de remoción, para este fin se usó un diseño experimental completamente al azar, en el cual el pH del agua se varió entre 10, 11, 12 y 13, el ozono fue dosificado a una tasa de 0,5 g h-1 por un periodo de 3 horas tomando muestras cada 30 minutos. Los ensayos fueron realizados para el agua residual real, suministrada por una curtiembre y agua residual sintética, a fin de comparar la remoción alcanzada en cada caso. El análisis de los resultados obtenidos permitió señalar que la mayor remoción se logró a pH 11 en el agua residual real, alcanzando un valor de 77,78%, aproximadamente 39% superior al alcanzado al mismo pH para el agua residual sintética. También se evaluó la cinética del proceso, obteniendo que los resultados se ajustan a una cinética de pseudo primer orden para la cual el coeficiente cinético fue de -0,0001 s-1, por último, se observó que después de cada ensayo se presentó disminución pH, lo cual confirma lo que químicamente debería suceder, formación de H2SO4 por la oxidación de sulfuros a sulfatos. Finalmente, se concluye que la remoción de sulfuros empleando ozono es una técnica aplicable para pH alcalino, permitiendo reducir tiempos de oxidación y convirtiéndose en una alternativa viable para aplicar en la industria del curtido de pieles. Abstract In this study, the removal of sulfides in wastewater from the process of peeling or depilating skins was evaluated, using ozone as an oxidizing agent. The effect of the initial pH on the removal process was determined, for this purpose a completely randomized experimental design was used, in which the pH of the water was varied between 10, 11, 12 and 13, the ozone was dosed at a rate 0.5 g h-1 for a period of 3 hours taking samples every 30 minutes. The tests were performed for the real wastewater, supplied by a tannery and synthetic wastewater, in order to compare the removal achieved in each case. The analysis of the results obtained showed that the highest removal was achieved at pH 11 in the actual wastewater, reaching a value of 77.78%, approximately 39% higher than that reached at the same pH for the synthetic wastewater. The kinetics of the process were also evaluated, obtaining that the results are adjusted to a kinetic of pseudo first order for which the kinetic coefficient was -0,0001 s-1, finally, it was observed that after each test there was a decrease pH, which confirms what chemically should happen, formation of H2SO4 by the oxidation of sulphides to sulfates. Finally, it is concluded that the removal of sulfides using ozone is a technique applicable for alkaline pH, allowing to reduce oxidation times and becoming a viable alternative to apply in the leather tanning industry. Resumo Neste estudo avaliou-se a remoção de sulfetos em águas residuais do processo de pelagem ou depilado de peles, utilizando ozônio como agente oxidante. Determinou-se o efeito do pH inicial sobre o processo de remoção, para este fim usou-se um desenho experimental completamente ao azar, no qual o pH da água variou-se entre 10, 11, 12 e 13, o ozônio foi dosificado a uma taxa de 0,5 g h-1 por um período de 3 horas tomando amostras a cada 30 minutos. Os ensaios foram realizados para a água residual real, subministrada por um curtume e água residual sintética, a fim de comparar a remoção alcançada em cada caso. A análise dos resultados obtidos permitiu assinalar que a maior remoção se logrou a pH 11 na água residual real, alcançando um valor de 77,78%, aproximadamente 39% superior ao alcançado ao mesmo pH para a água residual sintética. Também avaliou-se a cinética do processo, obtendo com que os resultados se ajustem a uma cinética de pseudo primeira ordem para a qual o coeficiente cinético foi de -0,0001 s-1, por último, observou-se que depois de cada ensaio apresentou-se diminuição do pH, o qual confirma o que quimicamente deveria suceder, formação de H2SO4 pela oxidação de sulfetos a sulfatos. Finalmente, conclui-se que a remoção de sulfetos empregando ozônio é uma técnica aplicável para o pH alcalino, permitindo reduzir tempos de oxidação e convertendo-se em uma alternativa viável para aplicar-se na indústria do curtimento de peles.

Microbial reduction of Cr(VI) to Cr(III) can mitigate environmental chromium toxicity. A chromium, cadmium and nickel tolerating strain TCL with 97% 16S rRNA gene sequence homology to Bacillus cereus was isolated from a derelict open-cast, Tasra Coalmine Lake of Jharia, India. It could tolerate up to Cr2000 [2,000 mg L−1 Cr(VI)] and completely reduce Cr200 within 16 h under heterotrophic condition. TCL grown in ≥ Cr500 exhibited multifarious stress responses particularly in its prolonged lag-phase, like cell aggregation, up to two-fold elongation, increased exopolysaccharide production, and stress enzyme activities. These were relieved by increasing inoculum size or nutrient content. Chromium reduction was constitutive, with maximum activities detected in loosely-bound exopolysaccharides and membrane fractions, followed by cytoplasm and spent media. Cr(VI) was efficiently reduced to Cr(III) and >90% was released in spent media. Cells also expressed Cr-induced active efflux pumps. Growing cells or its crude enzyme extracts could efficiently reduce Cr(VI) in diverse temperatures (15–45 °C), pH (5–9); and in presence of other metals (Cd, Cu, Mo, Ni, Pb), oxyanions (SO4−2, NO2−), and metabolic inhibitors (phenol, NaN3, EDTA). Growth and reduction were also detected in nutrient-limited minimal salt media, and contaminated leather industry effluent thereby making TCL a potential candidate for bioremediation.

BACKGROUND In 2012, Danish authorities submitted a proposal to the European Chemical Agency restricting the content of hexavalent chromium to a maximum of 3 ppm in leather goods. Following its adoption, this proposal was implemented in 2015 as a directive in the EU. OBJECTIVES To examine the temporal trend of chromium contact allergy in adult dermatitis patients patch tested between 2002 and 2017, and to determine clinical characteristics and causative exposures in these patients. METHODS All adult dermatitis patients patch tested between 2002 and 2017 were included. Patch test data were reviewed retrospectively. Comparisons were performed with the χ 2 test and logistic regression analysis. RESULTS A total of 13 379 adults aged 18 to 99 years were patch tested between 2002 and 2017. The overall prevalence of chromium allergy was 2.2%. An overall decreasing trend was found for the prevalence of chromium allergy (Ptrend = 0.00002). Specifically, a significant difference was found for the study periods 2010 to 2013 (Ptrend = 0.002) and 2014 to 2017 (Ptrend < 0.0001) as compared with 2002 to 2005. Leather remained the most important single cause of allergic contact dermatitis caused by chromium. The proportion of clinically relevant leather exposures increased from 42.3% during 2002 to 2009 to 54.8% during 2010 to 2017 (P = 0.04). CONCLUSIONS The prevalence of chromium allergy is decreasing. The EU Directive restricting the use of hexavalent chromium in leather goods is thought to be playing a central role in this change.

For the sake of the safe and efficient cyclic utilization of chrome leather shavings (CLS), the temporary stabilization of CLS during the storage and transport processes was optimized. Afterwards, the large-scale stabilized CLS degradation and collagen degradation product (CDP) extraction were completed. In this research, hydroxyapatite (HAP) and calcium hydroxide (Ca(OH)2) were for the first time used as stabilizers in the stabilization of CLS. The results showed that both Ca(OH)2 and HAP displayed resistance to chrome leaching, but HAP provided better stabilization effect than Ca(OH)2. The optimized stabilization conditions giving lower chromium leaching concentration were selected: 2% HAP, temperature 300 °C, reaction time 60 min, and initially added water contents of 50%. The reason for HAP and Ca(OH)2 stabilization was proved by energy dispersive X-ray spectroscopy (EDS). Subsequently, the exploitation value of the stabilized CLS was described by large-scale experiment. The hydrolysis of stabilized CLS could obtain the collagen degradation product (CDP), which had 3.52% of free amino content and a molecular weight of 3.4~30 kDa. The filter residue was treated by 5% sulfuric acid solution extraction and pressure filtration again. The extraction solution and final filter residue were dried separately to obtain chromium-containing organic compounds (COP) and industrial gypsum. The COP, used as a filling for tannery, contains 9.37% Cr2O3 content and 90.6% organic content. The industrial gypsum contains 68.37% CaSO4, 0.13% Cr2O3, and 31.5% residual organic or inorganic compounds, which can be used in building materials. No waste water or solid waste was discharged in this experiment process.

Leather manufacturing is the process of transforming animal skin into high value-added commodity. As a crucial step in the leather producing process, conventional chrome tanning could lead to discharge of chromium contaminant due to the low efficiency of chromium uptake. In this paper, a series of polyethylene glycol triazine derivatives’ tanning agent (PT) with different molecule weight was synthesized with one-step method and applied in the main tanning of hide. The chemical structure of the PT was detected by FT-IR and 1H-NMR. The application experimental results indicated that after 16% of PT tanning at pH of 6, the wet-white was endowed with shrinkage temperature over 80°C and thickening rate over 108%. The experimental results indicated that the PT tanning leather not only have a better physical and mechanical properties than commercial triazine derivatives tanning agent, but also the leather is endowed with the effects of outstanding thermal properties. Considering that the pickling process became unnecessary, a large number of neutral salts could be avoided, the chromium load in spent liquor decreased from 1288 mg/L to 0, and the total dissolved chlorine in spent liquor decreased from 15,360 to 9581 mg/L; no toxic and harmful substances such as chromium and aldehyde are introduced into the tanning process. Compared with the leather tanned with commercial triazine derivatives’ tanning agent, the leather tanned with PT showed a similar overall tanning properties and better environmental friendliness, which makes PT matches the integral requirements of the modern sustainable leather industry.

Leather industry plays an essential role in the world's economy; however, it also has a negative environmental impact due to the generation of significant quantities of wastes, some of which are classified as hazardous chemicals. Chrome tanning, the most popular tanning process, employs chromium salts, acids, and some other chemicals. Some dyes can be also a source of chromium. As a result, hexavalent chromium, a known carcinogenic and mutagenic, can be found in leather products and cause allergic dermatitis or trigger other diseases. For this reason, it is important to quantify the total amount of chromium in final leather goods, as well as the oxidation state in which this element is found. This paper aims to summarize chromium contamination due to the leather production processes, and to review the analytical methods that have been used to determine chromium's most abundant species: Cr(III) and Cr(VI) in leather and other matrices (foodstuffs, cosmetic products, environmental, and pharmaceutical samples). The international and European regulations are presented as well as the last academic developments to extract and quantify chromium species. The future outlook of pretreatment and quantification techniques are also discussed in this work, with a special focus on chromium interconversions.

International audience; Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract. The mix- ture was prepared at ambient temperature and prepared at 80°C to determine what reactions, if any, did occur between the collagen protein through its amino acids and the polyphenolic condensed tannin. The reaction pro- ducts obtained were analyzed by matrix assisted laser desorption ionization time-of-flight (MALDI ToF) mass spectrometry. Reactions between the two materials did appear to occur, with the formation of a relatively small proportion of covalent and ionic linkages at ambient temperature but a considerable proportion of covalent lin- kages tannin-protein amino acids and the disappearance of ionic bonds. The linkages between the two materials appeared to be by amination of the phenolic –OHs of the tannin by the amino groups of the non-skeletal side chains of arginine, and by esterification by the –COOH groups of glutamic and aspartic acid of the aliphatic alcohol-OH on the C3 site of the flavonoid units heterocycle of the tannin. The proportion of covalent linkages increases markedly and predominate with increasing temperatures. This tightening of the tannin-protein covalent network formed may be an additional contributing factor both to leather wear resistance and performance as well to leather shrinking when this is subjected to excessive temperatures.

Water pollution caused by tannery wastewater is an important issue in developing countries. Most studies have focused on inorganic chemicals represented by chromium as a tannery-related main pollutant. This is the first study in which pollution of water by tannery-related organic chemicals was assessed by a combination of qualitative and quantitative analyses. Our quantitative analysis showed that the maximum concentration of total phenolic compounds (phenols), consisting of phenol, bisphenol F, p-cresol and chlorocresol, in canal water in a tannery built-up area in Bangladesh was >67-fold higher than the Environmental, Health and Safety (EHS) guideline value. Mapping of our results indicated tanneries as the sources of phenols pollution. Our original depurative, a hydrotalcite-like compound consisting of magnesium and iron (MF-HT), could adsorb all kinds of phenols and exhibited the highest phenol adsorption ability (115.8 mg/g) among reported hydrotalcite-like compounds. The levels of phenols in canal water samples were reduced to levels below the guideline value by using MF-HT with assistance of a photocatalytic reaction. Moreover, the mean level of chromium (112.2 mg/L) in canal water samples was decreased by 99.7% by using the depurative. Thus, the depurative has the potential for solving the problem of tannery-related water pollution by phenols and chromium.

Food waste and fashion pollution are two of the most prominent global environmental issues. To alleviate the problems associated with food waste, while simultaneously contributing to sustainable fashion, the feasibility of making an alternative textile material with leather-like properties from fungal biomass cultivated on bread waste was investigated. The filamentous fungus, Rhizopus delemar, was successfully grown on waste bread in a submerged cultivation process, and fungal biomass was treated with vegetable tannin of chestnut wood. NMR and FTIR confirmed interactions between tannin and fungal biomass, while OM, SEM and AFM visualised the changes in the hyphae upon the tannin treatment. Thermal stability was assessed using TGA analysis. The wet-laid technique commonly utilised for paper-making was used to prepare sheets of hyphae. Some of the sheets were treated with glycerol and/or a biobased binder as post-treatment. Overall, three of the produced materials exhibited leather-like properties comparable to that of natural leather. Sheets from untreated biomass with only glycerol post-treatment showed a tensile strength of 7.7 MPa and an elongation at break of 5%. Whereas sheets from untreated biomass and tannin treated biomass with both glycerol and binder treatments led to tensile strengths of 7.1 MPa and 6.9 MPa, and the elongation at break of 12% and 17%, respectively. The enhancement of hydrophobicity after the binder treatment, helped to preserve the absorbed glycerol within the sheet and thereby the flexibility was retained when in contact with moisture. These findings demonstrate that bread waste-derived fungal sheets have great potential as environmentally friendly materials with leather-like properties.

BACKGROUND Allergic contact dermatitis caused by shoes is common and new relevant allergens have been identified. OBJECTIVES To investigate the pattern of type IV sensitization in patients with suspected allergic contact dermatitis of the feet related to shoes as a presumed culprit trigger. METHODS Retrospective analysis of data of the Information Network of Departments of Dermatology (IVDK), 2009-2018. RESULTS Six hundred twenty-five patients with presumed shoe dermatitis were identified in a cohort of 119���417 patients. Compared to patients with suspected contact sensitization from other allergen sources (n��=��118���792), study group patients were more frequently sensitized to potassium dichromate (10.8% vs 3.5%), colophony (7.2% vs 3.7%), mercaptobenzothiazole (MBT; 4.0% vs 0.6%), mercapto mix (4.6% vs 0.6%), and p-tert-butylphenol formaldehyde resin (1.6% vs 0.5%). Sensitizations to urea formaldehyde resin, melamine formaldehyde resin, glutaraldehyde, tricresyl phosphate, and phenyl glycidylether were rare. Moreover, reactions to compounds in the leather or textile dyes test series were scarce. CONCLUSION A distinct sensitization pattern was observed in patients with suspected allergy to shoe materials. Although substances with low sensitization rates should be removed from the leather and shoe patch test series, novel potential allergens should be added.

Chrome-free metal tanning agent has been considered as eco-friendly in the leather industry. However, extensive crosslinking reactions of metal species on the leather surface restrain their uniform penetration into the hierarchical nanoscale leather matrix. Thus, masking agents with appropriate coordination ability are needed. Herein, the selective degradation of hemicellulose in corncob was achieved with 92.5% of conversion in an AlCl3–H2O system, obtaining oligosaccharides masking agent with high purity and leaving cellulose and lignin in the solid residue for other valuable use. Subsequently, H2O2 oxidation was performed to introduce –CHO/–COOH into oligosaccharides and reduce their molecular weights, thereby enhancing coordination ability and reducing ligand dimension. The post-oxidized reaction fluids together with additional Zr species were subjected to leather tanning, in which the oligosaccharides could coordinate with Al/Zr species and promote the penetration of metal species into the leather matrix. By controlling the hemicellulose degradation and oligosaccharide oxidation, an appropriate concentration of oligosaccharides with proper –CHO/–COOH contents allowed the efficient masking effect of the oligosaccharides. As a result, a uniform distribution of Al/Zr species was observed on the cross section, and 83.5 °C of shrinkage temperature was obtained for the chrome-free tanned leather.

Tannery sludge usually has high content of trivalent chromium (Cr(III)) and ammonium-nitrogen (NH4+-N). It is important to make a critical evaluation of the releasing behaviors of Cr(III) and NH4+-N from tannery sludge before its use on improving soil fertility in agricultural applications. For this purpose, static batch and dynamic leaching experiments with different mathematical models were carried out to simulate the Cr(III) and NH4+-N releasing kinetics from tannery sludge sampled in a typical tannery disposal site in North China, and their influencing factors were also discussed. The results showed that a larger solid-liquid ratio, a higher temperature, and a lower pH value of the leaching solution were beneficial for the release of Cr(III) and NH4+-N from the tannery sludge. The release kinetics of Cr(III) and NH4+-N followed parabolic diffusion and simple Elovich models both in the static and dynamic leaching conditions, indicating that the release was a complex heterogeneous diffusion process. The NH4+-N was easy to be leached out and its released amount reached 3.14 mg/g under the dynamic leaching condition (pH 7), whereas the released amount of the Cr(III) was only 0.27 &mu, g/g from the tannery sludge. There was a positive correlation coefficient between dissolved Fe and Cr(III) in the leachate under different leaching conditions, and the calculated average ratio of Fe/Cr(III) concentration was 3.56, indicating that the small amount of the released Cr(III) came from the dissolution of Cr0.25Fe0.75(OH)3 minerals in tannery sludge.

Tanning leather using green biomass-derived polyaldehyde (BPA) is a promising approach to eliminate the widespread Cr pollution in leather industry, but unsatisfactory thermal stability and mechanical strength of the correlated resultant leather limited its industrial application. Herein, we report a green methodology to strengthen BPA tanned leather via introducing chitosan derivatives to crosslink with free aldehyde groups on dialdehyde carboxymethylcellulose (DCMC) tanned leather. H2O2 was employed for purposely modifying chitosan to prepare low-molecular chitosan (LMC) with lower positive charge. The interactions between chitosan/LMC and DCMC were investigated to elucidate the strengthening mechanism. Owing to the weakened hydrogen bonding network and higher accessibility of amino groups on LMC, LMC could react much easier with aldehyde groups on DCMC. Moreover, LMC could efficiently penetrate into the internal fiber networks of leather for further interlocking, which enhanced the thermal stability and the lubricating degree of crust leather and, as a result, the tensile and tear strengths were significantly improved by 79.3% and 25.3%, respectively. Therefore, the use of LMC can promote the widespread application of BPA tanned leather, benefiting to the complete elimination of hazardous Cr pollution.

Chromium-rich tannery sludge (TS) is a hazardous industrial waste. Although vermicomposting can be an effective remediation pathway; but, the unique waste degrading efficiency of Eudrillus eugeniae is least explored. The present work showcases an efficient earthworm-mediated protocol for TS sanitization deploying E. eugeniae. Changes in pH, TOC (%), nutrients (NPK), metals (Cr, Cd etc.) and microbial diversity were monitored in various E. eugeniae mediated TS based vermibed. Total N, P, and K availability increased by 2–5 folds upon vermicomposting with 3–4 folds reduction in C/N ratio. Moreover, substantial removal of Cr (89%), Cd (88%), and Zn (79%) was recorded in the substrate. Bioaccumulation of these metals in the gut significantly reduced the pollution load in the finished products. The corresponding augmentation of microbial density and low respiratory CO2 release from the vermibeds substantiated the environmental proficiency of vermitechnology.

Due to its carcinogenic character, the presence of formaldehyde in leather continues to be a subject of great concern. By using formaldehyde scavengers, it is possible to reduce the formaldehyde content in leather. In this work, the potential ability of three different compounds (ethylene urea, pyrogallol and gallic acid) to reduce the formaldehyde content in splits leathers treated with formaldehyde resins (melamine-formaldehyde and dicyandiamide-formaldehyde) is assessed. This capacity is compared with that of a fourth scavenger (hydroxylamine sulphate) already used in tanneries. The evolution of the formaldehyde content with time is also considered, as well as the potential coadjuvant effect of other compounds such as mimosa extract and an acid dye (Acid Black 234). Hydroxylamine sulphate initially showed the highest ability to reduce formaldehyde content. However, after a certain time, this ability proved to be inferior to the ability of other compounds due to the reversibility of the reaction between hydroxylamine and formaldehyde. Pyrogallol showed a higher ability than gallic acid when used in the final wash of leather processing. However, the treatment with pyrogallol results in a darkening of the leather; this darkening limits its use. Gallic acid may be a good alternative to formic acid as the final fixing agent in leather processing when the presence of formaldehyde in leathers is suspected. The use of gallic acid in the final wash or as a fixing agent fulfils the formaldehyde content limit (65–75¿mg/kg) of the major brands in leather goods in direct contact with the skin. The addition of 2% of gallic acid in the final wash of leather processing resulted in formaldehyde content reductions that varied from 65% to 85%. However, further experiments are required to assess the influence of gallic acid on the fastness properties and the coloration acquired by the treated leathers. The joint effect of gallic acid in the final wash or as a fixing agent and mimosa extract as a retanning agent in formaldehyde content reduction is even enhanced by subsequently using a dye with amino groups in its chemical structure. Reducing the formaldehyde content by using scavengers can contribute to the achievement of a cleaner production in those sectors (leather, textile, wood) that use formaldehyde resins.

In order to assess the effects of tannery effluents (TE) in organism health, juveniles of Prochilodus lineatus were submitted to in situ tests at four different river locations: site A – upstream of the tannery; site B – next to the tannery; and sites C and D – downstream of the tannery. After 96 h exposure in the river, samples of fish tissue, river water and sediment were collected in order to quantify chromium (Cr) concentrations. Tissue samples were used to assess the activity of ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), the content of glutathione (GSH) and metallothionein (MT) and the occurrence of lipid peroxidation (LPO) and DNA damage. Higher Cr concentrations were detected in the water and sediments from site B and in the liver of fish confined at site B, compared to the other sites. Fish caged at site B demonstrated higher levels of liver MT and hepatic EROD activity in relation to fish caged at the other sites. Moreover, fish from site B presented increased liver and branchial GST activities, as well as more GSH in the liver, than fish from site A. There were no significant variations in the occurrence of LPO and DNA damage among fish caged at the different sites. Thus, TE increased Cr levels in the water, sediments, and fish livers and stimulated the synthesis of MT and GSH and the activities of EROD and GST. In conclusion, TE affect the quality of the river and promote changes in biochemical biomarkers and Cr accumulation in P. lineatus.

In artisanal tanneries, the skins are immersed in cereals fermented by naturalmicrobial flora in order to reduce the pH of the skin, an essential condition for carrying out the final step. The environmental thermal variation alters thefermentation process and affects the quality of the final product. The aim of this work was to isolate lactic acid bacteria from cereals mixture fermented in an artisanal tannery and to evaluate in vitro the acidifying activity of the strains as a first step for the formulation of a starter culture. In most samples, a prevalence of cocci (95%) was observed with respect to bacilli. The best acidifying strains were identified by phenotypic and genotypic techniques as Enterococcus faecium CRL 1943 (rapid acidification at 37 °C) and Leuconostoc citreumCRL1945 (high acidifying activity at 18 °C). In addition, the biomass production of the selected strains was analyzed at free and controlled pH (bioreactors 1.5 L). The production of biomass was optimal at controlled pH, with a higher growth (0.5?1.1 log units). Both strains were compatible,allowing their inclusion in a mixed culture. These lactic strains could contribute to the systematization of the tanning process. Fil: Correa Deza, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Martos, Gladys Irma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Nuñez, Martha Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad del Norte Santo Tomás de Aquino; Argentina Fil: Fiori, Mario. Instituto Nacional de Tecnología Industrial; Argentina Fil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina

The prosperity and development of tannery industry have brought about rapid economic growth. However, the tannery landfill without anti-seepage measures in the early stage has generated masses of environmental hazards owing to the lack of awareness in environmental protection. Therefore, it is imperative to pay much attention to the understanding of environmental hazards from tannery waste. In this study, solid samples and groundwater samples were collected from a tannery landfill to study the effect of the characteristic pollutants produced by tanning on chromium distribution with other coexisting substances. The results showed that significant correlations were demonstrated between multiple coexisting substances (total organic carbon, total petroleum hydrocarbons, total nitrogen, Cr, F, Ca, Cu and Pb), indicating the possible same source or they coming from the same tannery production stage. The weights of positive effects and negative effects of coexisting substances on total Cr distribution in the profile decreased in the order: total nitrogen > Cu > Ca > Pb > total organic carbon > F > SO42– > Cd, and Ni > Cl > Hg, respectively. Moreover, the simulation of Visual MINTEQ showed that the cations were mainly bound to Cr as CrO42−, while the anions were bound to Cr3+. This study provided a new perspective on the selection of remediation strategies for Cr-contaminated sites to avoid secondary environmental pollution caused by the release of coexisting heavy metals.

In the present study, a pilot scale horizontal subsurface flow constructed wetland (CW) system planted with Phragmites karka; longitudinal profile was studied. The wetland was fed with tannery wastewater, pretreated in a two-stage anaerobic digester followed by a sequence batch reactor. Samples from each CW were taken and analyzed using standard methods. The removal efficiency of the CW system in terms of biological oxygen demand (BOD), chemical oxygen demand (COD), Cr and total coliforms were 91.3%, 90%, 97.3% and 99%, respectively. The removal efficiency for TN, NO3− and NH4+-N were 77.7%, 66.3% and 67.7%, respectively. Similarly, the removal efficiency of SO42−, S2− and total suspended solids (TSS) were 71.8%, 88.7% and 81.2%, respectively. The concentration of COD, BOD, TN, NO3−N, NH4+-N, SO42 and S2− in the final treated effluent were 113.2 ± 52, 56 ± 18, 49.3 ± 13, 22.75 ± 20, 17.1 ± 6.75, 88 ± 120 and 0.4 ± 0.44 mg/L, respectively. Pollutants removal was decreased in the first 12 m and increased along the CW cells. P. karka development in the first cell of CW was poor, small in size and experiencing chlorosis, but clogging was higher in this area due to high organic matter settling, causing a partial surface flow. The performance of the pilot CW as a tertiary treatment showed that the effluent meets the permissible discharge standards.

El proceso productivo de transformación de las pieles en cuero desarrollado en la industria curtiente genera diferentes tipos de residuos que deben tener un adecuado manejo. Esta investigación consistió en buscar un tratamiento de separación de cal de los residuos de descarne de la etapa de desencalado del proceso de curtición que le permitan ser aprovechados en diferentes usos. Se seleccionaron descarnes encalados, para la aplicación de 6 tratamientos con tres repeticiones de desencalado mediante baños con agua a temperatura ambiente controlando los factores tiempo en 3 niveles (2,3 y 4 Horas) y ácido sulfúrico como agente desencalante en dos niveles (1 y 2 N) . Los mejores resultados en este proceso se obtuvieron con el tratamiento con una concentración de ácido sulfúrico al 2N y un tiempo de agitación de 3 horas.

Made available in DSpace on 2018-11-29T03:50:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Composting has been suggested as an efficient method for tannery sludge recycling before its application to the soil. However, the application of composted tannery sludge (CTS) should be monitored to evaluate its effect on the chemical and microbial properties of soil. This study evaluated the time-dependent effect of CTS on the chemical and microbial properties of soil. CTS was applied at 0, 2.5, 5, 10, and 20 Mg ha(-1) and the soil chemical and microbial properties were evaluated at 0, 45, 75, 150, and 180 days. Increased CTS rates increased the levels of Ca, Cr, and Mg. While Soil pH, organic C, and P increased with the CTS rates initially, this effect decreased over time. Soil microbial biomass, respiration, metabolic quotient, and dehydrogenase increased with the application of CTS, but decreased over time. Analysis of the Principal Response Curve showed a significant effect of CTS rate on the chemical and microbial properties of the soil over time. The weight of each variable indicated that all soil properties, except beta-glucosidase, dehydrogenase and microbial quotient, increased due to the CTS application. However, the highest weights were found for Cr, pH, Ca, P, phosphatase and total organic C. The application of CTS in the soil changed the chemical and microbial properties over time, indicating Cr, pH, Ca, phosphatase, and soil respiration as the more responsive chemical and microbial variables by CTS application. Univ Fed Piaui, Soil Qual Lab, Agr Sci Ctr, Teresina, PI, Brazil Sao Paulo State Univ, Brasil Univ, Dept Technol, Descalvado, SP, Brazil Wageningen Environm Res Alterra, Wageningen, Netherlands Wageningen Univ, Aquat Ecol & Water Qual Management Grp, Wageningen, Netherlands Sao Paulo State Univ, Brasil Univ, Dept Technol, Descalvado, SP, Brazil CNPq: 471347/2013-2 CNPq: 305102/2014-1 CAPES: CAPES 23038.007660/2011-51

Some of the most polluting activities occur in bovine skin processing. Tannery generates effluents containing high concentrations of heavy metals and organic compounds. The phases composing the leather production process generate a large volume of tannery effluents that are often discarded in aquatic environments without any previous treatment. However, the effect these xenobiotics have on adult representatives belonging to the class Amphibia remains unknown. Thus, the aim of the present study is to assess the geno- and cytotoxic effects of tannery effluent on adult male bullfrogs (Lithobates castesbeianus) exposed to it. Accordingly, the animals were divided into the following groups: negative control (tannery effluent-free water), positive control (cyclophosphamide), and effluent (water added with 5% tannery effluent). The animals were euthanized for blood collection, and erythrocyte analyses were conducted after 35 and 90 days of exposure. The micronuclei (MN) frequency and the frequency of other nuclear abnormalities in each of the animals in the experimental groups were assessed in 2000 erythrocytes. According to the present results, the exposure to tannery effluents increased MN frequency as well as other nuclear abnormalities (i.e., lobed nuclei, binucleated cell, kidney-shaped nuclei, notched nuclei, and apoptotic cell) in the erythrocytes of animals in the effluent group and in the positive control group after 35 and 90 exposure days. Thus, the current study corroborated the hypothesis that the tannery effluent has aneugenic and clastogenic potential in adult male bullfrogs (L. castesbeianus). The present study is the first to report such effect.

Previous studies involving the oral exposure of mice to tannery effluents have found neurotoxic effects. However, studies about the effects the dermal exposure to pollutant have on the cognitive function of females have not been found in the literature. Thus, the aim of the current study is to investigate whether the dermal exposure of female Swiss mice to tannery effluents (2 h/day for 20 days) can cause cognitive impairment, as it was already evidenced in male Swiss mice. Furthermore, based on the administration of vitamin C (before or after the exposure to the xenobiotic), the current study also aims to assess the protective effect of vitamin C in female Swiss mice dermally-exposed to the tannery effluent. Female Swiss mice exposed to the tannery effluent (without vitamin supplementation) have shown lower novel object recognition index during the test session of the novel object recognition task, and they have descended significantly faster from the inhibitory avoidance platform when they were compared to mice belonging to the other groups, therefore evidencing memory deficit. However, the test performance of females receiving vitamin C was similar to that of control animals. Thus, the current study confirms the initial hypothesis that the dermal exposure to the pollutant, even for a short period, causes cognitive deficit in female Swiss mice. The herein presented findings also provide evidence that the mechanisms of action of the tannery effluent in these animals are related to oxidative damages in specific brain regions directed to the formation of short memory to perform aversive and object recognition tasks.

Galactomyces geotrichum was utilized as a potential biosorbent for the treatment of tannery effluent under controlled environmental conditions. Tannery effluent treatment was studied through parametric experiments to study the effect of effluent pH (3.0–10.0), initial COD (1100–4400 mg/L), and biosorbent dosage (0.3–3.0 g/L).The zeta potential of the biosorbent was determined and found to influence the optimal pH. Increase in effluent COD values resulted in decreased COD removal percentages which attributed to limited availability of surface active sites. The equation relating the COD removal efficiency and biosorbent dose was proposed. Two popular kinetic models, namely pseudo-second order and power function models, were employed to the experimental data. Pseudo-second order model proved to be a good fit with high values of regression coefficient (R 2 > 0.960). Potential application of a fungal biosorption process was explored and the optimal process parameters were identified.

A global demand for efficient re-utilization of produced solid wastes, which is based on the principles of re-use and recycling, results to a circular economy, where one industry's waste becomes another's raw material and it can be used in a more efficient and sustainable way. In this study, the influence of a by-product addition, such as aluminum anodizing sludge, on tannery waste (air-dried sludge) stabilization was examined. The chemical characterization of tannery waste leachate, using the EN 12457-2 standard leaching test, reveals that tannery waste cannot be accepted even in landfills for hazardous wastes, according to the EU Decision 2003/33/EC. The stabilization of tannery waste was studied applying different ratios of tannery waste and aluminum anodizing sludge, i.e. 50:50, 60:40, 70:30 and 80:20 ratios respectively. Subsequently, the stabilization rate of the qualified as optimum homogenized mixture of 50:50 ratio was also tested during time (7, 15 and 30 days). Moreover, this stabilized product was subjected to phytotoxicity tests using the Lepidium sativum, Sinapis alba and Sorghum saccharatum seeds. The experimental results showed that aluminum anodizing sludge managed to stabilize effectively chromium and organic content of tannery waste, which are the most problematic parameters influencing its subsequent disposal. As a result, tannery waste stabilized with the addition of aluminum anodizing sludge at 50:50 ratio can be accepted in non-hazardous waste landfills, as chromium and dissolved organic carbon concentrations in the respective leachate are below the relevant regulation limits, while the stabilized waste shows decreased phytotoxicity.

The effect of adding position for tannery sludge in a co-processing cement rotary kiln on the chromium leachability of the cement produced was assessed in laboratory scale. Cement clinkers and pastes were produced and evaluated based on analysis of the cement quality, characterization of the clinker crystalline phases, and extraction toxicity of heavy metals in the resulting cements (using the toxicity characteristic leaching procedure (TCLP) and the Chinese GB/T 30810-2014 standard). It was found that the amount of sludge added (up to 0.7% of the feed composition) and use of different addition points for the sludge had no detrimental effect on the resulting cement quality. The retention ratios of heavy metals during sintering were related to their volatilities and the sludge addition points. The Cr concentration in leachate generated by the TCLP was far below the regulatory limit (5mg/L); however, when using the GB/T 30810-2014 procedure, the Cr concentration in the leachate exceeded the regulatory limit (200μg/L) when the sludge addition was greater than or equal to 0.5% and it was added at the kiln main burner position. Based on our laboratory study, tannery sludge might be added at the decomposing furnace addition point to reduce the Cr leachability of the resulting cement.

The vitrification process was applied for the stabilization and solidification of a rich in chromium ash that was the by-product of incineration of tannery sludge. Six different batch compositions were produced, based on silica as the glass former and sodium and calcium oxides as flux agents. As-vitrified products (monoliths) were either composed of silicate matrices with separated from the melt Eskolaite (Cr2O3) crystallites or were homogeneous glasses (in one case). All as-vitrified products were thermally treated in order to transform them to partially crystallized, i.e. devitrified products. Devitrification is an important part of the work since studying the transformation of the initial as-vitrified products into glass-ceramics with better properties could result to stabilized products with potential added value. The devitrified products were diversified by the effective crystallization mode and separated crystal phase composition. These variations originated from differences in: (a) batch composition of the initial as-vitrified products and (b) thermal treatment conditions. In devitrified products crystallization led to the separation of Devitrite (Na2Ca3Si6O16), Combeite (Na4Ca4Si6O18) and Wollastonite (CaSiO3) crystalline phases, while Eskolaite crystallites were not affected by thermal treatment. Leaching test results revealed that chromium was successfully stabilized inside the as-vitrified monoliths. Devitrification impairs chromium stabilization, only in the case where the initial as-vitrified product was a homogeneous glass. In all other cases, devitrification did not affect successful chromium stabilization.

A spent tanning bath contains high concentration of salts, chromium and protein. The treatment system for removal of chlorides or chromium from this effluent is expensive. In this context this waste has to be reused. Our study focuses on the application of advanced oxidation processes for protein removal present in a tanning bath. To improve the quality of the chromium tanning bath, two electrochemical processes (electrooxidation and peroxi-electrocoagulation process, PEP) are investigated in a batch reactor. The effects of operational parameters such as reactor configuration, current density and electrolysis time on chemical oxygen demand (COD) and protein removal efficiency are examined. Results indicated that under the optimum operating range for process, the COD and protein removal efficiency reached 53 and 100%, respectively. The optimum values are determined for the hybrid process (PEP) under 0.13 A·cm−2 over 2 h. The treated tanning bath is used as a tanning solution in leather processing. The influence of chromium salt dose, pH solution, stirring time and contact time on the leather characteristic is evaluated. The hides tanned after the addition of 0.25% of commercial chromium salt, at pH solution, leaving them stirring for 4 h with a contact time of 2 days, and showed good hydrothermal stability and physical characteristics of leather.

This paper presents the comprehensive evaluation results of physical and environmental performances for a novel wet-white (chrome-free) leather manufacturing. The tanning process is optimized as 15 wt% tannic acid (TA) combination with 4 wt% Laponite nanoclay, giving the leather with shrinkage temperature (Ts) above 86 °C. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) measurements indicate that Laponite can be evenly and tightly bound within the leather matrix, which is further confirmed by scanning electron microscopy and energy dispersive X-ray (SEM-EDX) spectroscopy analysis. The resultant wet-white leathers have reasonable good physical properties that can meet the standard requirements for furniture leather without containing hazardous Cr(VI) and formaldehyde. Further life cycle assessment (LCA) studies shows that tanning process is the main contributor to environmental impact categories in the wet-white tanning process, and tannic acid is the most significant substance factor. Compared to conventional chrome tanning, the wet-white tanning process exhibits much lower abiotic depletion potential (ADP), and reduced global warming potential (GWP) and human toxicity potential (HTP) impacts due to the nature of vegetable tanning; whereas, GWP excluding biogenic carbon and energy consumption are higher owing to prolonged run time.

The effectiveness of heat-inactivated fungal biomass a fermentation waste of newly isolated laccase enzyme producer Leiotrametes flavida was studied for Cr (VI) removal in water and applied for Cr (VI) removal from tannery effluent. Adsorption parameters pH, biomass concentration and contact time were optimized using Box-Behnken design of response surface methodology. The adsorption process fits the Langmuir isotherm. Thermodynamic and kinetic studies showed that the process is spontaneous at ambient temperature and followed the second-order kinetics model, respectively. The values of the kinetic model indicated that the adsorption process is a combination of physisorption and chemisorption. Chromium adsorption onto the biomass was confirmed by SEM-EDAX, FTIR, XPS and XRD analysis. XPS analysis confirmed the reduction of Cr (VI) to Cr (III). The amount of chromium adsorbed was 72.38 % and 68.33 % for water and effluent, respectively. Chromium adsorbed onto biomass was desorbed at pH 9 with 1 M NaOH. Total chromium desorbed was 61.40 and 59.38 percent from water and effluent, respectively. The amount of Cr (III) in the desorbed sample was 71 and 68 percent, respectively. The heat-inactivated biomass of Leiotrametes flavida is a suitable material for efficient Cr (VI) removal and detoxification.

The work reports the use of polyamidoamine dendrimers (PAMAM) and a cross-linking agent, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide (EDC/NHS) or 4-(4,6-dimethoxy[1,3,5]triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM), for the thermal stabilization of dermal bovine collagen. The efficiency of EDC/NHS/PAMAM and DMTMM/PAMAM in the cross-linking of collagen is correlated to the increase of the collagen shrinkage temperature (Ts), measured by differential scanning calorimetry (DSC). An alternative enzymatic protocol was adopted to measure the degradability of EDC/NHS/PAMAM tanned hides, these data are correlated to the thermal stability values measured by DSC. In the presence of PAMAMs, EDC/NHS provides very high stabilization of bovine dermal collagen, giving Ts of up to 95 &deg, C, while DMTMM achieves lower stabilization. Preliminary tanning tests carried out in best reaction conditions show that EDC/NHS/PAMAM could be an interesting, environmentally-sustainable tanning system which is completely free of metals, formaldehyde, and phenols. Two new unreported dendrimeric species were synthesized and employed.

Chemical transformations of modified collagen for prediction of effective formation and stabilization of the derma structure with the use of montmorillonite dispersions treated by different modifying agents were studied. Identification of chemical interactions was estimated using infrared spectroscopic studies on gelatin, amino acid composition of which is close to collagen. The existence of active in interaction carboxylic, amino-, peptide and hydrogen groups in the collagen structure contributes to effective structuring of derma. During processing of skins into leather, the transformation of bonds in collagen occurs. In this case, chemical materials interact with the functional groups of protein and form new chemical bonds. This contributes to stabilization of the structure of derma. This results in the formation of a capillary-porous structure with the required level of operational and hygienic properties of leather. IR spectroscopic analysis revealed effective physical and chemical interactions between collagen and modified montmorillonite dispersions. This is proved by the formation of numerous bonds involving functional groups of gelatin and active centers of the mineral. The biggest changes are observed in high-frequency and low-frequency regions. Accordingly, the spectra characterize valence fluctuations involved in the formation of hydrogen, ionic and covalent bonds. This allows claiming that pre-chromed gelatin subsequently treated with aluminum-modified montmorillonite dispersion has more coordination bonds. This is caused by the hydroxo-complex ions of Cr (ІІІ) and Al (ІІІ), which are located between the silicate layers. At the same time, the presence of pre-chromed gelatin ensures the formation of additional intermolecular bonds, which can influence the stability of properties and structuring of derma collagen. Thus, there are grounds to argue about the possibility of more efficient use of chromium compounds during the tanning process. Due to the introduction of the composition based of montmorillonite modified by aluminum compounds, a decrease in consumption of chromium compounds will be achieved. This will make it possible to solve the problem of making production ecologically friendly and to enhance safety of leather for children’s footwear.

A possible impact of sample preparation on the chemical fractionation results is generally underestimated in studies of forms of occurrence of heavy metals in river sediments. Our analysis of the recently published results of sequential extraction of chromium has revealed the effect of sample grinding on the result of determination of mobile chromium fractions in river sediments. This observation has been experimentally verified along with the analysation of potential effect of river sediment drying conditions on chromium distribution pattern. The studies were carried out on river sediments polluted with tannery effluents (Cr, 29.2–233 mg/kg). The determined content of chromium bound to carbonates in powdered samples was 2 to 7 times higher than those in raw river sediment samples. It was shown that the main reason was the different kinetic characteristics of chromium leaching in these sediments. Using the shrinking core model, it was found that diffusion through the “ash layer” was the rate-controlling step during the extraction of the carbonate fraction of chromium. It has been additionally confirmed that common air drying of sediment samples does not affect the results of chemical fractionation of chromium. The results of our studies are also vital for the assessment of environmental risk posed by river sediments polluted with heavy metals. In the case of sediment samples used in this study, powdering changed the risk category (RAC) from low risk to high risk. Hence, in order to achieve a realistic assessment of chromium mobility and environmental risk, it is advisable to use raw samples, despite their poorer homogeneity, and thus, lower precision of chemical fractionation results. Electronic supplementary material The online version of this article (10.1007/s10661-019-7727-2) contains supplementary material, which is available to authorized users.

The leather industry is a major source of environmental pollution in India. The wastewater generated by leather industries contains very high pollution parameters due to the presence of a complex mixture of organic and inorganic pollutants even after the treatment at a Common Effluent Treatment Plant (CETP) and disturbs the ecological flora and fauna. The nature, characteristics and toxicity of CETP treated wastewater is yet to be fully elucidated. Thus, this study aims to characterize and evaluate the toxicity of CETP treated tannery wastewater collected from the Unnao district of Uttar Pradesh, India. In addition to measuring the physico-chemical parameters, the residual organic pollutants was identified by GC-MS analysis and phytotoxicity, cytotoxicity and genotoxicity of the treated wastewater was evaluated using Vigna radiata L. and Allium cepa L. Results showed that the treated wastewater contained very high pollution parameters (TDS 3850 mg/L, BOD 680 mg/L, COD-1300 mg/L). GC-MS analysis revealed the presence of various types of residual organic pollutants including benzoic acid, 3-[4,-(T-butyl) Phenyl] furan-2-5-dione, benzeneacetamide, resorcinol, dibutyl phthalate, and benzene-1,2,4-triol. Further, toxicological studies showed the phytotoxic nature of the wastewater as it inhibited seed germination in V. radiata L. and root growth of A. cepa. Genotoxicity was evidenced in the root tip cell of A. cepa where chromosomal aberrations (stickiness, chromosome loss, C-mitosis, and vagrant chromosome) and nuclear abnormalities like micronucleated and binucleated cells were observed. Thus, results suggested that it is not safe to discharge these wastewater into the environment.

Use of sodium chloride to preserve animal skins and hides is becoming increasingly untenable due to stringent environmental regulations. In the present research work, a combination of sparingly soluble alkali and water-soluble polymer of ethylene oxide has been used to preserve skins with an objective of total elimination of common salt for preservation. A comprehensive study has been made for evaluating various parameters, such as dehydration and rehydration behaviours of skins, microbial growth, emission loads and physico-chemical characteristics of the cured skin to validate the salt-free preservation system developed. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. The new curing system has been found to be effective in preserving the skin as indicated by the various parameters studied and the final leather quality. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional preservation method is evident from environmental impact assessment studies.

This investigation focused on the simultaneous decrease of tannery sludge and the reduction of its high chromium (Cr(VI)) content. This was accomplished through the addition of mixed bacterial strains that were cultured in the laboratory, subsequent to their isolation from tannery sludge. The results indicated that under anaerobic conditions, the amount of the tannery sludge was decreased by 27% with these mixed bacteria. The impacts of various parameters were explored, such as pH, processing duration, strain inoculation, and temperature. Along with the decreased volume of sludge, the Cr(VI) concentration was lowered as well. Among the isolated bacterial strains, WY601 (belonging to Stenotrophomonas sp.) demonstrated the highest Cr(VI) resistance; from an initial concentration of 300 mg L−1, the Cr(VI) level was decreased by 90% within 65 h. Hexavalent chromate reductase was found to be localized primarily within the extracellular membrane or adsorbed to its surface, and a mechanism was proposed for the removal of Cr(VI) via WY601. Further, the WY601 isolate was found to be tolerant to other toxic heavy metals. In summary, the isolated mixed bacterial strains in our study demonstrated a strong potential for the treatment of tannery sludge, as they could simultaneously decrease its volume while lowering high Cr(VI) levels.

Salt-based preservation is practiced for decades in the leather industry because of its versatility, cost-effectiveness, and availability. The salt removed from the soaking process causes significant pollution including organic and elevated total dissolved solids (TDS). Hence, a low-salt skin preservation method using commercial sodium polyacrylate with a reduced quantity of sodium chloride aiming to retain leather properties and pollution reduction was the principal focus of the study. Commercial sodium polyacrylate initially characterized for water absorption capacity along with structural and functional properties is confirmed by NMR and IR spectroscopic techniques. In preliminary experiments, the process parameters attained optimized conditions of sodium polyacrylate (SPA) quantity (5%), a minimal amount of salt (15%), and contact time (4 h) required for skin preservation. Besides, reusability studies after SPA recovery (95%) were applied to skins with an optimized quantity of SPA and salt subsequently stored for 15 days along with control (40% salt). The results revealed that SPA with low salt aided an adequate curing efficiency with a substantial reduction (> 65%) of TDS and comparable physical and organoleptic properties on par with the conventional method. Overall, SPA supported low-salt skin preservation reduces pollutant load (TDS) caused due to using of 40% sodium chloride in the conventional curing process.

The populations of wild animals are declining in many parts of the world in response to man-made alterations in the environment. Environmental contamination due to heavy metals discharge from industry may contribute to the decline of wild animal populations by impacting their reproduction, growth, and development. In the leather tanning industry, chromium (Cr) is used as a basic component, but it is a potent toxicant that can affect many of the physiological functions of animals. In the current study, we investigated the reproductive toxicity of industrial Cr in female small Indian mongooses inhabiting a tannery area. Adult female specimens were live trapped from February 2015 to January 2016. Blood and other body tissues (ovaries, kidneys and liver) of the captured specimens were collected along with soil and water samples from the environment for analysis. The Cr concentrations were found significantly ( p < 0.0001) increased compared to control in the environment, blood, and all body tissues of the animals. Estradiol and progesterone levels were found to be significantly decreased in comparison with control ( p < 0.0001), along with reduced ovarian weights, while follicle stimulating hormone (FSH) and luteinizing hormone levels were found significantly ( p < 0.0001) elevated. Light microscopy revealed significantly decreased in comparison with control ovarian follicle numbers ( p < 0.0001) and diameters, vacuolization of the oocytes, and a significantly higher percentage of atretic follicles inside the ovary. We conclude that Cr discharged from the tanneries is absorbed by the exposed female small Indian mongoose, leading to ovarian dysfunction with potential impairment of reproductive function.