Tannery Waste Research Articles

Isolation and biochemical characterization of a novel serine protease identified from solid tannery waste metagenome

Isolation and biochemical characterization of a novel serine protease identified from solid tannery waste metagenome

Spatial distribution and morphological transformation of chromium with coexisting substances in tannery landfill

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.

Sauaeda Fruticusa is Hyperaccumulator of Chromium and Lead

Sauaeda Fruticusa is Hyperaccumulator of Chromium and Lead

Production of Bio-Fertilizer through Composting of Tannery Wastes with Cow- Dung and Rice Bran

Tannery waste is made from nutrients and organic compounds that enhance soil fertility thereby improving plants and microbial growths. This study was designed to investigate the application of tannery wastes to form compost material in a mixture with cow-dung and rice brand. The treatments were prepared and tested for a period of sixty (60) days. The compost was characterized by electric conductivity (EC) of 10.11µs/cm, pH of 7.62 and Carbon-Nitrogen (C:N) ratio of 28.8. Total concentrations of Chromium, Lead, Cadmium, Copper, Zinc and Iron in mg/kg were 57.2, 0.92, 12.50, 60.50, 13.60 and 1101.00 respectively. However, total bacterial counts decreased from 8.2 x108cfu/g to 1.8 x106cfu/g after the 60days. The compost characteristics indicate about 80% germination index which may suggest the removal of most of the phototoxic compounds.

PROCESS FOR CHROMIUM (VI) REMOVAL FROM MECHANIZED TANNERY WASTEWATER USING ACTIVATED CARBON OBTAINED FROM TANNERY SOLID WASTES

This study offers an integrated process for treatment and recycling of tannery waste, it has a dual purpose. First the activated carbon has been prepared from leather shaving and buffing dust by physical activation. Both the raw material (leather waste) and the prepared activated carbon were analyzed by DTG, Thermo Gravimetric Analysis TGA, and scanning electron microscope. The adsorption tests of methylene blue and iodine onto the raw material and the prepared adsorbent were carried out and it was found that the adsorption capacity of the activated carbon was enhanced by the physical activation. The Activated Carbon was then characterized by equation of Brunauer-Emmett-Teller surface area and Fourier transforms infrared spectroscopy (FTIR). The Brunauer-Emmett-Teller surface area was found to be 491.05 and 242.60 m2/g for activated carbons prepared from Leather Savings and Buffing Dust respectively and the functional groups on the adsorbent surface were mainly CN, NH, OH, CO and CS. Secondly, the performance of the prepared activated carbon was assessed by adsorption of chromium (VI) from a synthetic solution, and then the chromium (III) present in the tanning effluent. The results revealed a decrease of chromium by 76% and 73% for the activated carbons prepared from Leather Savings and Buffing Dust, respectively

Anaerobic Co-Digestion of Tannery Wastes and Untreated/Pretreated Oat Straw

Anaerobic Co-Digestion of Tannery Wastes and Untreated/Pretreated Oat Straw

Progress in sustainable technologies of leather wastes valorization as solutions for the circular economy

The tanning industry generates a large amount of waste, which should be managed following the principles of the circular economy. It is estimated that leather processing produces 200 times more waste than total product output. This paper presents a review of the methods that offer recycling of materials or energy from tannery waste, including chemical, thermal and biological techniques. These processes can recover a number of secondary feedstocks such as chromium, nutrients, collagen hydrolysate, fat, biogas, and anaerobic digestate, which can be used in other industrial processes. The review also covers the current legislative status of waste and its impact on the environment. Smart and sustainable valorization technologies enable a high degree of recycling with no burden on the environment.

Simple strategy synthesis of manganese cobalt oxide anchored on graphene oxide composite as an efficient electrocatalyst for hazardous 4-nitrophenol detection in toxic tannery waste

Hazardous 4-nitrophenol (4-NP) and its isomers are very harmful to humans, plants, and animals even at very low concentrations. Consequently, it is very urgent and essential to identify 4-NP in the environment with a simple and accurate method. Herein, MnCo2O4 (MCO) nanosphere was synthesized by simple co-precipitation process using sodium hydroxide as a precipitating agent and subsequent elimination by calcination. The MCO@GO is prepared by ultrasound irradiation at room temperature. Graphene oxide was anchored with MCO nanospheres were performed excellent electrocatalytic activity owing to their Mn2+/Mn3+ and Co2+/Co3+ have an impressive synergistic effect (MCO) and large active surface area (GO). The prepared MCO@GO nanocomposite was characterized by different analytical techniques namely XRD (crystal nature), FTIR (functional group), FESEM, TEM (morphological analysis), XPS (elemental state). The electrochemical characterization was monitored by CV and DPV. The MCO@GO nanocomposite was drop cast on a glassy carbon electrode is referred to as MCO@GO/GCE for the electrochemical determination of 4-NP with good practical applicability. The peak current was increased while increasing the concentration of 4-NP from 0.5 µM to 151.5 µM with a regression equation y = 0.4952(µM) + 3.092 and correlation coefficient R2 = 0.9921. From this slope value, the LOD and sensitivity were determined to be 0.012 µM and 6.868 μA μM−1 cm−2. The sensor was successfully used for practical application of the 4-NP determination in toxic tannery wastes with a strong agreement with the added value and the recovery results. The objective of our work has afforded to readers a thorough understanding of the synthesis and electrochemical sensing applications of MCO@GO and some guidance in future research.

Small scale photo bioreactor treatment of tannery wastewater, heavy metal biosorption and CO2 sequestration using microalga Chlorella sp.: a biodegradation approach

Recently, mass production of lipid along with heavy metal reduction is gaining momentum due to their cost-effective and greener approach towards waste water treatment. The purpose of this study is to investigate the small scale photo bioreactor treatment of tannery effluent using Chlorella sp. isolated form Yercaud lake, Tamil Nadu, India. The results showed a significant decrease in the heavy metals content in the tannery effluent after the treatment. Maximum reduction of the heavy metal Chromium (Cr) of 10.92 mg L−1 was recorded, followed by Cobalt (Co)-7.37 mg L−1, Nickel (Ni)-9.15 mg L−1, Cadmium (Cd)-8.48 mg L−1, Lead (Pb)-12.54 mg L−1, Zinc (Zn)-11.56 mg L−1 and Copper (Cu)-10.71 mg L−1 at the end of the 20th day of treatment. The microalgae, Chlorella sp. was analyzed for their biosorption ability and the maximum biosorption capacity (qmax) rate against heavy metals was 81.36, 70.53, 82.15, 63.29, 58.92, 83.43, 64.83 µg L−1 for Cr, Pb, Ni, Cd, Co, Zn, and Cu respectively. It matched with the Langmuir and Freundlich kinetics models. The maximum CO2 utilization was found to be 60.50% and maximum concentration of lipid, carbohydrate and protein was found to be 0.95 g L−1, 250 µg mL−1 and 160 µg mL−1, respectively. The presence of various groups such as hydroxyl, alkyl, carbonyl and carboxylic acids was confirmed using Fourier transform infrared analysis. Thus, the isolated microalgae showed good biosorption ability towards the various heavy metal pollutants from tannery waste water.

Trace elements concentration in soil and plant within the vicinity of abandoned tanning sites in Bangladesh: an integrated chemometric approach for health risk assessment

An effective toxicological assessment of soil-metal bioavailability and plant translocation processes is needed in view of the growing negative impact of trace element pollution on the terrestrial environment and human health. This study was conducted to assess the toxicological processes that regulate the plants’ trace element absorption into their tissues, the suitability for human use, the potential sources of trace elements, and the risk to human health, using an integrated research methodology. Soils and sweet potato plants were collected from agricultural fields near the tannery waste disposal sites of Dhaka City, Bangladesh and inductively coupled plasma mass spectrometers (ICP-MS) were used to analyze the essential and toxic elements. The mean concentrations of total elements in soil followed the descending order of Fe > Zn > Mn > Cr > Ni > Pb > Cu > As > Cd and in plant Fe > Zn > Cu > Cr > Ni > Mn > Pb > As > Cd. In the edible tissues of sweet potato, the concentrations of essential and toxic elements exceeded the maximum permissible levels, indicating not safe for human consumption. The translocation factor (TF) revealed that studied elements are more accumulated in the leaves than tubers. The enrichment factor revealed minimal to very high enrichment of essential and toxic elements in the plant parts while the contamination factor showed low to very high contamination. Considering the health risk of toxic elements from plant samples, As and Pb caused non-cancer and cancer risk on human health. However, the present results suggested that regular monitoring of these essential and toxic elements in soil and plants as well as other food materials around the abandoned tannery waste disposal sites are necessary to prevent excessive build-up of these elements in the food chain.

Tannery sludge and urban waste compost in the production of Solanum melongena L. through regression and multivariate analysis

In vegetable production, seedling propagation is one of the most important steps as it directly influences the final performance of the plants. In order for such condition, the propagation substrate must be in good condition. The objective of this work was to evaluate the effect of different combinations of tannery sludge and urban waste compost as substrates in comparison to the commercial substrate Maxfértil® on the growth and quality of eggplant seedlings. The experiment was conducted in a greenhouse using a randomized block design with eight treatments and six replications. The commercial substrate was Maxfértil®, a crushed pine bark, with limestone, and seven treatments with increasing proportions of tannery sludge/decreasing urban waste compost (0/100; 10/90; 30/70; 50/50; 70/30; 90/10 and 100/0 v/v). Characteristics of emergence, growth, quality and leaf nitrogen (N) content were evaluated. No difference was found in the emergence of eggplant seedlings among the different treatments used; however, the growth characteristics, quality and N content featured significant effects when the seeds were propagated in alternative substrates. Regression adjustments pointed to an optimal range of 41–49% of tannery sludge associated with urban waste compost for the evaluated characteristics. The strong correlation between SPAD and N content shows its potentiality in detecting N deficiencies in seedlings. The use of tannery sludge residues associated with urban waste compost seems to be an appropriate and sustainable practice for recycling with high agronomic potential.

Synergistic effect of the activated carbon addition from leather wastes in chitosan/alginate-based composites.

In this work, chitosan/alginate composites were developed by the gelation method with the addition of different amounts of activated carbon produced from tannery waste (ACTW). The performance of these composites was verified through the adsorption of the textile dye Remazol Brilliant Blue R (RBBR). A synergistic effect was observed by the addition of ACTW; with a specific surface area up to 45.584 m2/g, the maximum adsorption capacity was 300.96 mg/g. The synergy was due to the reduction in steric hindrance, with the adsorption capacity 1.2 times higher than expected. The material was regenerated with sodium hydroxide for 10 cycles. The composite containing 30% ACTW (AC30) was applied in the treatment of real textile effluent, with 30% reductions in the biochemical oxygen demand (BOD), 39% in the chemical oxygen demand (COD), 78% in turbidity, and 67% in color.

Teknologi Pengolahan Kandungan Kromium dalam Limbah Penyamakan Kulit Menggunakan Proses Adsorpsi: Review

The waste management issue is one of the biggest problems in the industries recently. Every industry has a high probability of releasing toxic by-product to the environment in the form of waste. One example is in the leather tanning industry. Leather tanning waste still removes harmful metals in its waste, such as heavy metal chromium (Cr). Chromium is used to produce finer skin products. About 30-40% chromium will be carried in the tanning liquid waste. The high chromium levels remaining and carried away in the waste can cause acute and chronic toxicity to the environment and even very harmful to living things. Adsorption is one of the highly recommended methods available to overcome this problem. Relatively low handling costs, simple processes, and the possibility of being recycled are some of the adsorption process's advantages. In addition, the adsorption process can be maximized by using adsorbents that have specific potential specifications for chromium absorption. This article reviews batch and continuous adsorption methods in the processing of chromium content in tannery waste.

Continuous photocatalytic set-up assisted with nano TiO2 plate for tannery wastewater treatment.

A novel photocatalytic continuous system has been proposed for the treatment of tannery waste water, which has high levels of environmental pollutants. The purification process was performed by passing wastewater on a titanium dioxide (TiO2)-coated surface, which is continuously activated by irradiation of ultraviolet light. To improve the yield of the process, ferric chloride (FeCl3) was used as a coagulation agent. The organic and inorganic compounds, as well as the microorganisms in the tannery wastewater media, were degraded through a photocatalytic process. The results revealed that total dissolved solids and total suspended solids contents were significantly decreased from 8,450 and 8,990 mg·L-1 to 4,032 and 4,127 mg·L-1, respectively. Furthermore, the chemical oxygen demand content of the sample was reduced from 370 to 50 mg·L-1 after the addition of 100 mL of FeCl3 and 4 h of treatment. The same results were observed for the elimination of sulfate and chromium ions, which led to a decline in electrical conductivity. This suggests that introducing 100 mL of FeCl3 as the coagulation agent and continuous treatment with photocatalityc set-up could be considered as an effective method for the purification of tannery wastewaters.

Metagenomic insights into taxonomic diversity and metabolic potential of bacterial communities associated with tannery waste-contaminated soils

Long-term exposure to anthropogenic stressors can lead to perturbations in microbiomes, either selecting for novel and biotechnologically important biotypes, or reductions in the microbial diversity and disequilibrium of ecosystem services. Consequently, analysis of variations in microbial structure and function in stressful environments remains a critical issue in microbial ecology. In this study, the taxonomic structure of bacterial communities inhabiting tannery waste dumpsite soils was evaluated comparatively with those from non-contaminated soils using 16S rRNA gene sequencing. Furthermore, the metabolic potential of these communities was inferred from community level physiological profiling fingerprints. The dumpsite has been receiving tannery waste since 1982; hence, the soils are laden with heavy metals including chromium, zinc, sodium, and potassium. Consequently, the following significant differences between bacterial communities from contaminated and non-contaminated soils were observed: (1) bacterial communities from the contaminated soils were characterized by lower species diversity, albeit at comparable species evenness (Simpson index); (2) long term contamination of soil shifted the bacterial community structure to a distinct core microbiome dominated by bacterial groups such as Halomonas, Balneolaceae, Aliifodinibius, Serinicoccus, Gracilimonas, Marinobater, Penticoccus, Fordinicurvata, Dietzia, and Norcadioides. These are characteristic of saline, metal-laden environments and have potentially high organo-pollutant degradative properties; and (3) bacterial communities from the contaminated soils exhibited a robust metabolic potential utilizing both natural and anthropogenically derived polymers at a higher rate. Overall, these results highlight tannery waste dumpsite soils as microbial diversity hotspots and potential reservoirs for exploration of novel biotechnological tools for bioremediation and industrial applications.

Investigating the chromium status, heavy metal contamination, and ecological risk assessment via tannery waste disposal in sub-Saharan Africa (Kenya and South Africa).

To mitigate the negative environmental and public health concerns associated with increased industrial discharges amid the rapid industrial growth, sub-Saharan African countries have instituted several environmental regulations and policies. However, a paradox of good environmental policies but inadequate enforcement exists in most of these countries, with information on the pollution level unknown due to poor monitoring resources. In this study, potentially toxic heavy metal contamination and physicochemical characteristics in effluents and dumpsite soils of two tanneries in Kenya (DB) and South Africa (BO) were evaluated during the dry and rainy season of 2018. Pollution levels and ecological risk in the dumpsite soils were assessed by adopting geoaccumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and ecological risk index (PRI). The results showed that the mean final effluent concentration fortotal dissolved solids (TDS), chemical oxygen demand (COD), and Cr, Cu, Fe, Ni, Zn, and Cd for BO (2127, 890, 1.82, 1.38, 1.96, 0.60, 1.21, and 1.16, respectively) and DB tanneries (8157, 1369, 7.90, 0.69, 1.05, 0.60, 1.72 mg/L, respectively) were above the limits of emission guidelines. The mean Cr and Cr(VI) concentrations in tannery dumpsite soils (204.9 ± 29.1 and 0.31 ± 0.01 and 943 ± 29.8 and 0.4 ± 0.07 mg/kg for BO and DB, respectively) and Fe (2498 ± 62 mg/kg in DB) exceeded acceptable thresholds of the World Health Organization (WHO), Food and Agriculture Organization (FAO), and local background levels. A positive strong correlation was observed between Cr and organic matter, OM (r > 0.7, p < 0.001), electrical conductivity, EC (r=0.99, p < 0.05), and As (r = 0.62; p < 0.05), suggesting a common anthropogenic point source. The mean PLI values of 5.3 and 1.6 for DB and BO dumpsites indicated significant pollution of the soils with heavy metals, specifically Cr (Igeo = 18 and 2.4 for DB and BO, respectively). Similarly, PRI values of 174.8 and 57.4 indicated a moderate and low potential ecological risk for DB and BO tannery dumpsite, respectively, with several plants sampled within the two sites exhibiting elevated levels of Cr contamination. In summary, these results provide scientific insights on the need for both improved effluent management and treatment technologies of tannery wastes, coupled with the strengthening of continuous monitoring and enforcement for compliance of industrial discharges in sub-Saharan countries.

A New Multibranch Model for Metals in River Systems: Impacts and Control of Tannery Wastes in Bangladesh

A new multibranch Integrated Catchment (INCA) model INCA-Metals has been developed to simulate the impact of tannery discharges on river systems. The model accounts for the key chemical reaction kinetic processes operating as well as sedimentation, resuspension, dilution, mixing and redistribution of pollutants in rivers downstream of tannery discharge points and for mine discharges or acid rock drainage sites. The model is dynamic and simulates the daily behaviour of hydrology and eight metals, including cadmium, mercury, copper, zinc, lead, arsenic, manganese and chromium, as well as cyanide and ammonia. The model is semi-distributed and can simulate catchments, tributaries and instream river behaviour. The model can also account for diffuse pollution from rural runoff as well as point sources from effluent and trade discharges. The model has been applied to the new Savar tannery complex on the Dhaleshwari River system in Bangladesh to assess the impacts on pollution levels in the river system and to evaluate a set of treatment scenarios for pollution control, particularly in the dry season. It is shown that the new effluent treatment plant at Savar needs to significantly improve its operation and treatment capability in order to alleviate metal pollution in the downstream Dhaleshwari River System and also protect the Meghna River System that falls in the Bay of Bengal.

Structural characterization and functional annotation of microbial proteases mined from solid tannery waste metagenome

We report structural characterization of proteases mined in silico from solid tannery waste (STW) metagenome. The physico-chemical analysis revealed the molecular weight of selected query proteases in the range of 34–43 kDa except 52.46 kDa for Cp-6. Secondary structure analysis suggested the dominance of α-helices (26–51 %) followed by β-sheets (13–34 %). Conserved regions in the selected proteases were identified using multiple sequence alignment. Diversity analysis of the proteases was performed by aligning with their best hits and already characterized proteases of similar families. The 3D structures of 19 selected amino acid sequences were deduced using homology modeling and evaluated following Ramachandran plots (R-plots), stability of the 3D conformation, and overall quality factor (G factor). The R-plots of all structures had 96.4–98.9 % residues in the favoured region, whereas 0-0.8 % lied in the outlier region. Fifteen modeled protein structures passed the quality assessment criteria and were subsequently used for molecular docking. All models showed two domains except Cp-6, which had an extra domain. Ligand binding sites and active sites were identified using sequence and structural homologs of the respective protease molecules. Serine, lysine, and serine of different conserved motifs were specified as the active site residues in carboxypeptidases, whereas serine, aspartate, and histidine were specific to aminopeptidases Ap-1, Ap-2, and Ap-4. Further, Ap-8 and Ap-9 required Mn2+ for enzyme activity along with histidine and glutamate in their active sites. These 3D structures were used for molecular docking with their specific peptide ligands to obtain stable docked conformations. Successfully docked complexes indicated the catalytic activity of these enzymes in hydrolyzing the peptide ligand. The structural and functional insights gained from our study may help in the identification of novel industrially important proteases after validation through experimental studies.

Transglutaminase Crosslinked Gelatin Films Extracted from Tanned Leather Waste

The production of biodegradable polymers has proved to be a promising alternative, since these materials have accelerated degradation, contributing to the reduction of residues and the reduction of environmental pollution. The tannery wastes contain considerable collagen and can be used for gelatin extraction and film production for use in agriculture. Gelatin-based films, however, present some challenges for practical application, such as permeability and solubility in water, parameters that can be improved through the crosslinking process by employing enzymes, promoting the union of polymeric gelatin chains. In this context, the action of the enzyme transglutaminase was investigated to improve the properties of gelatin films recovered from leather and chitosan residues, which were evaluated according to thickness, solubility, permeability, mechanical properties, and soil degradation. The results indicated that the enzyme concentration in the films had a significant effect on the properties of water permeability and solubility and strain to rupture. The evaluation of soil degradation showed that films with higher enzyme addition took longer to be degraded.

Combination of Thermal, Hydrometallurgical and Electrochemical Tannery Waste Treatment for Cr(III) Recovery

A combination of thermal (500–750 °C in air) and hydrometallurgical (acidic) treatments have been applied to dried tannery sludge, resulting in the initial conversion of Cr(III) to Cr(VI) and its subsequent leaching as wastewater with high Cr(VI) concentration content (3000–6000 mg/L), presenting an extraction efficiency over 90%. The optimal electrochemical conditions for the subsequent Cr(VI) reduction with respect to acid concentration and acid kind were established by applying appropriate rotating disc electrode (RDE) experiments, using a glassy carbon (GC) electrode, and found to be equal or higher than 0.5 M H2SO4 (for the respective Cr(III) concentration range studied). The result from leaching Cr(VI) wastewater was further treated in small electrochemical bench-scale reactor for its conversion back to Cr(III) form, potentially reusable in the tanning industry. Ti-based anodes and a reticulated vitreous carbon (RVC) cathode were used to treat small (350–800 mL) samples in batch, as well as in batch-recirculation prototype electrochemical reactors, under the application of constant current or appropriately applied potential to achieve Cr(VI) conversion/reduction efficiency over 95%.