Search

Mercury (Hg) is one of the most potent toxic heavy metals that distresses livestock, humans, and ecological health. Owing to uncontrolled exposure to untreated tannery industrial effluents, metals such as Hg are increasing in nature and are, therefore, becoming a global concern. As a result, understanding the thriving microflora in that severe condition and their characteristics becomes immensely important. During the course of this study, two Hg-resistant bacteria were isolated from tannery wastewater effluents from leather factories in Kolkata, India, which were able to tolerate 2.211 × 10− 3 M (600 µg/ml) Hg. 16 S rDNA analysis revealed strong sequence homology with Citrobacter freundii, were named as BNC22A and BNC22C for this study. In addition they showed high tolerance to nickel (Ni) and Chromium (Cr) at 6.31 × 10− 3 M (1500 µg/ml) and 6.792 × 10− 3 M (2000 µg/ml) respectively. However, both the isolates were sensitive to arsenic (As) and cadmium (Cd). Furthermore, their antibiotic sensitivity profiles reveal a concerning trend towards resistance to multiple drugs. Overuse and misuse of antibiotics in healthcare systems and agriculture has been identified as two of the main reasons for the decline in efficacy of antibiotics. Though their ability to produce lipase makes them industrially potent organisms, their competence to resist several antibiotics and metals that are toxic makes this study immensely relevant. In addition, their ability to negate heavy metal toxicity makes them potential candidates for bioremediation. Finally, the green mung bean seed germination test showed a significant favourable effect of BNC22A and BNC22C against Hg-stimulated toxicity. [ABSTRACT FROM AUTHOR]

Heavy metal contamination has emerged as a global environmental concern, with tannery effluents serving as a significant source of these pollutants. The discharge of tannery effluents (TEs) into natural ecosystems has given rise to a spectrum of catastrophic risks, exacerbating concerns related to public health, safety, and environmental integrity. This current study focuses on the mycoremediation of the heavy metals present in TE, employing the mycelia of Pleurotus opuntiae, an environmentally sustainable solution. The toxicity of TE was rigorously characterized by evaluating a range of physicochemical parameters in accordance with the American Standard and Testing Methods. Subsequently, various diluted concentrations of effluent (25%, 50%, 75% and 100%) were incorporated into MDA media to assess the tolerance index (TI) of P. opuntiae. Notably, the highest TI was observed in the 25% and 50% TE concentrations, while no growth was observed in the 75% and 100% groups due to the exceptionally elevated heavy metal content. P. opuntiae demonstrated remarkable efficacy in heavy metal removal, with the most substantial reductions recorded in the 25% diluted effluent (91.3% Pb, 72.2% Cr and 66.5% Zn), closely followed by the 50% diluted effluent. The highest intracellular bioaccumulation was observed for Pb (17.2 µg/g), outperforming Cr (14.5 µg/g) and Zn (8.5 µg/g) in mycelia grown in 25% diluted effluent. To elucidate the detoxification mechanisms underlying metal removal, various characterizations of the mycelium were conducted, including SEM, FTIR, and XRD analyses. Furthermore, LC–MS analysis shed light on the pivotal role of metabolites in regulating heavy metals within the physiological metabolism of P. opuntiae. Moreover, an upsurge in the concentration of the stress marker, metallothionein, and augmented activity of antioxidant enzymes, like SOD, CAT, LPO and GSH, collectively suggested the significant role of antioxidants in mitigating reactive oxygen species (ROS) and heavy metal toxicity. These comprehensive findings provide a solid foundation for understanding the mechanisms responsible for heavy metal removal by P. opuntiae and pave the way for the development of effective remediation strategies for decontaminating the effluents discharged by the leather industry, contributing to the preservation of our environment and to public well-being. [ABSTRACT FROM AUTHOR]

Tannery effluents add pollutants to the aquatic environment. The characterization of responses to toxic exposure at the molecular level of biological systems is a major challenge in ecotoxicology because it enables the unraveling of mechanisms of toxicity, the discovery of novel biochemical markers, and early diagnoses of exposure and effects. The three major classes of antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (Gpx) were analyzed in the liver, testes, and ovary of Channa striatus to delineate the impact of tannery effluents on these enzymes. The oxidative stress biomarkers showed a significant reduction (p<0.05) in their activities among the control and experimental groups exposed to both 10 and 1 % concentrations of the tannery effluents. The SOD activity was reduced to 96.13 % in the ovary compared to the liver (60.73 %) and testes (47.89 %) after 30 days of exposure to a 10 % concentration of the tannery effluents. However, the activities of catalase and glutathione peroxidase decreased to 58.59 % and 43.64 % in the testes when compared to the liver and ovary. [ABSTRACT FROM AUTHOR]

The effluents generated by the tannery industry have a high content of chromium and other toxic elements, representing a potential threat to ecosystems. An eco-friendly alternative to treat these effluents is the use of microorganisms, such as fungi, with the capacity to biosorb heavy metals. The present work aims to determine the effect of the molasses concentration, pH variation, and time on the removal of total chromium using the filamentous fungus Trichoderma spp. An experimental design was adopted using pH (4 and 6), concentrations of molasses (0.5 and 1%), and time (8 and 12 days) as independent variables. The Trichoderma inoculum was constant in all the treatments. The different treatments were evaluated after 0, 8, and 12 days by taking 50 mL of sample from each bioreactor. The chromium concentration was subsequently determined in each sample. The results show that treatment 3 (1% molasses and pH 4) showed higher chromium removal after both 8 and 12 days. The concentrations of total chromium decreased from 665 mg/mL to values of 568 mg/mL by day 8 and 486 mg/mL by day 12. These values are, however, still above the maximum threshold imposed by Peruvian law regarding the discharge of non-domestic effluents into the sewage system. The results show that Trichoderma spp. can increasingly remove chromium from the effluent with longer incubation periods. However, future studies are necessary to determine the mechanisms of chromium biosorption by the fungus and the influence of other physicochemical parameters. [ABSTRACT FROM AUTHOR]

• Isolation and characterization of the bacterial species. • Microorganism resistant to heavy metals was identified. • SEM and FTIR for identifying heavy metal remediation. • Bioremediation confirmation through seed germination studies. In this investigation, heavy metal-resistant microorganisms from tannery effluent were isolated, characterized, and identified. Also, to study their phytotoxicity towards Macrotyloma uniflorum. The characterized bacterium, identified as Stenotrophomonas rhizophila , showed different resistance levels and sensitivity to too many antibiotics tested. In the current investigation, nine aerobic strains of bacteria from the tannery effluent were identified. Based on the tests looked at, such as the lowest inhibitory concentration, the relatively heavy metal analysis showed the maximum percentage of degradation of Na 2 HAsO 4 was 91.6 %, Hg was 91 %, and Cr was 78.66 %, respectively. Furthermore, the IAA generation exhibited greater tolerance and stimulated plant development. The isolated bacteria showed MARI against the evaluated antibiotics at a rate of 30 %. On the other hand, the study found that inoculation with metal-tolerant bacteria dramatically enhanced plant growth and metal accumulation and protected plants from the damaging effects of heavy metals. The selected bacteria shield plants from the growth-inhibiting effects of heavy metals (Cd and Cr). According to these results, such metal-tolerant bacteria that promote plant growth are valuable resources exploited to create bio-inoculants that would increase the effectiveness of heavy metal removal. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of trivalent chromium from leather tanning mud waste leachates (containing ca 6 g.L−1 Cr(III)) to its hexavalent form was carried out using a PbOx/Pb anode electrode in a prototype small (0.4 L) cylindrical batch electrochemical reactor. The PbOx/Pb anode was prepared by electrochemical anodization at constant current (75 mA cm−2 for 30 min) in a sulfuric acid solution and characterized by the cyclic voltammetry technique to investigate the effect of pH on the process. It was found that at pH = 3, Cr(III) oxidation prevails over the competing water oxidation-oxygen evolution reaction (OER), hence increasing the efficiency of the process. A detailed study of pH (0–3), current density (12–24 mA cm−2), and cell type (divided-undivided) effects on bulk electrolysis of Cr(III) leachates in the batch prototype reactor resulted in process optimization. At pH = 3, 12 mA cm−2 and a cathode inserted in a porous diaphragm envelope, nearly 70% conversion was achieved at a nearly 60% current efficiency, among the highest in the previously reported literature. The method (further optimized with an ion-selective membrane separator) could offer an attractive route for tannery Cr(III) conversion to Cr(VI) for reuse as an etchant or electroplating agent. [ABSTRACT FROM AUTHOR]

Effluents from the leather tanning industry contain diverse pollutants, including hazardous heavy metals, posing threats to public health and the surrounding environment. Indigenous bacterial isolates can represent an eco-friendly approach for tannery wastewater treatment; however, phenotypic characterization is necessary to determine whether these strains are suitable for bioremediation. In the present study, we analyzed seven new Enterococcus faecium strains and two new Bacillus subtillis strains isolated from effluents from the Southern Tunisian Tannery (ESTT). We evaluated phenotypic features beneficial for bioremediation, including biofilm formation, hydrophobicity, and exoenzyme activities. Additionally, we examined characteristics naturally occurring in environmental bacteria but less desirable in strains selected for bioremediation, such as antibiotic resistances and pathogenicity indicators. The observed phenotypes were then compared with whole-genome analysis. We observed biofilm production in two slime-producing bacteria, B. licheniformis RLT6, and E. faecium RLT8. Hydrophobicity of E. faecium strains RLT1, RLT5, RLT8, and RLT9, as well as B. licheniformis RLT6 correlated positively with increasing ESTT concentration. Exoenzyme activities were detected in E. faecium strains RLT2, RLT4, and RLT7, as well as B. licheniformis RLT6. As anticipated, all strains exhibited common resistances to antibiotics and hemolysis, which are widespread in nature and do not hinder their application for bioremediation. Importantly, none of the strains exhibited the pathogenic hypermucoviscosity phenotype. To the best of our knowledge, this is the first report consolidating all these phenotypic characteristics concurrently, providing a complete overview of strains suitability for bioremediation. The study evaluates the bioremediation potential of seven Enterococcus faecium strains and two Bacillus subtillis strains isolated from the effluents from the Southern Tunisian tannery (ESTT), which pose threats to public health and environmental integrity. The analysis primarily examines the phenotypic traits crucial to bioremediation, including biofilm formation, hydrophobicity, and exoenzyme activities, as well as characteristics naturally occurring in environmental bacteria related to heavy metal resistance, such as antibiotic resistances. Several strains were found to have high bioremediation potential and exhibit only antibiotic resistances commonly found in nature, ensuring their application for bioremediation remains uncompromised. The results of the exhaustive phenotypic analysis are contrasted with the whole genome sequences of the nine strains, underscoring the appropriateness of these bacterial strains for eco-friendly interventions in tannery wastewater treatment. [ABSTRACT FROM AUTHOR]

Background: The tannery industry is a potent environment polluting agent worldwide. Chromium (VI) is a major heavy metal in tannery effluents and their accumulation in soil and water is a serious environmental problem. This study investigates the capacity of indigenous bacteria isolated from tannery effluents for tolerance to chromium (VI). Methods: The chromium tolerance of isolates assessed through both agar dilution and broth microdilution methods. Isolates were identified by morphological and biochemical analysis. The tolerance of isolates to cadmium, nickel, lead, and vanadium and also their multidrug-resistant (MDR) profile were determined. Then the top isolate was characterized via 16S rRNA sequencing and its growth temperature and pH were optimized. Finally, the kinetic of chromium biosorption and chromium removal efficiency was determined using a Nutrient broth medium and wastewater containing 20 mg/L chromium, respectively. Results: Of 32 screened chromium tolerant isolates, 14 isolates with higher chromium tolerance were selected for further study. 78.57% of isolates represented simultaneous MDR and Multi Heavy Metal tolerance (MHMT) phenotypes and MDR indices of 0.2–1 indicating their source from niches with high antibiotic contamination. However, there was no significant correlation between MDR and MHMT phenotypes among isolates. The top isolate was identified as Lactococcus lactis and showed optimal growth at pH 6 and 25 °C. The maximum chromium biosorption occurred at the end of the exponential phase upon optimized conditions and the approximate chromium removal efficiency of 52.5% was obtained. Conclusion: The isolated bacteria specifically L. lactis after more evaluations, may show the potential for bioremediation of chromium from tannery effluents. [ABSTRACT FROM AUTHOR]

The increase of anthropogenic activities has led to the pollution of the environment by heavy metals, including chromium (Cr). There are two common oxidative states of Cr that can be found in industrial effluents the trivalent chromium Cr(III) and the hexavalent chromium Cr(VI). While the hexavalent chromium Cr(VI) is highly toxic and can trigger serious human health issues, its reduced form, the trivalent chromium Cr(III), is less toxic and insoluble. Leather tanning is an important industry in many developing countries and serves as a major source of Cr(VI) contamination. Globally, tannery factories generate approximately 40 million m3 of Cr-containing wastewater annually. While the physico-chemical treatments of tannery wastewater are not safe, produce toxic chemicals and require large amounts of chemical inputs, bioremediation using chromium-resistant bacteria (CRB) is safer, efficient and does not produce toxic intermediates. Chromium-resistant bacteria (CRB) utilise three mechanisms for Cr(VI) removal: biotransformation, biosorption and bioaccumulation. This review will evaluate the three Cr(VI) detoxification mechanisms used by bacteria, their limitations and assess their applications for large-scale remediation of Cr(VI). This can be helpful for understanding the nature of Cr(VI) remediation mechanisms used by bacteria, therefore, bridging the gap between laboratory findings and industrial application of microorganisms for Cr(VI) removal.

The anaerobic treatment of tannery effluents from the different process stages are limited by the various toxicants that are mainly added as feed chemicals. The segregated effluents present an opportunity for co-treatment to abate inhibition, supplement deficient nutrients and/or promote resource recovery using anaerobic digestion. This study investigated the feasibility of anaerobic co-digestion of beamhouse (BH) and pre-treated tanyard (TY) effluents using the standardised biochemical methane potential (BMP) protocol. It was established that all reactors were active, while those with higher TY compositions and operating at very high/low inoculum to substrate ratios (3

The aim of this work was to evaluate the pollutant load from tannery effluents treated by chemical coagulation (CC) followed by electro-oxidation (EO), performed in two different experimental batch-recirculated setups, one with a BDD anode and the other with Ti/Pt/PbO2 and Ti/Pt/SnO2-Sb2O4 anodes (PS). Results were compared with those obtained from EO of the raw sample. CC was performed with a Fe3+ concentration of 0.25 g L−1, and the applied current densities for EO in each setup were 60 mA cm−2 for BDD and, in the PS setup, 20 and 40 mA cm−2 for Ti/Pt/SnO2-Sb2O4 and Ti/Pt/PbO2, respectively. During CC, removals of 27% in chemical oxygen demand (COD), 14% in total nitrogen, 100% in sulfide, and 73% in Cr(VI) were observed. COD removal in the EO of the raw sample was higher than that obtained for the combined CC + EO, for both setups, showing that the organic compounds removed by CC are mainly those that would be more easily removed by EO. For most of the other parameters related with carbon and nitrogen, the removals for CC + EO were higher than for EO alone. During EO, sulfide is converted to sulfate, especially with BDD. Concerning Cr(VI) concentration, it increases during EO, in particular for PS setup. Combined treatment, with both setups, proved to be an effective choice to treat tannery effluents. [ABSTRACT FROM AUTHOR]

The metabolites of the fungal strain Rhizopus oryaze were used as a biocatalyst for the green-synthesis of magnesium oxide nanoparticles (MgO-NPs). The production methodology was optimized to attain the maximum productivity as follows: 4 mM of precursor, at pH 8, incubation temperature of 35 °C, and reaction time of 36 h between metabolites and precursor. The as-formed MgO-NPs were characterized by UV-Vis spectroscopy, TEM, SEM-EDX, XRD, DLS, FT-IR, and XPS analyses. These analytical techniques proved to gain crystalline, homogenous, and well-dispersed spherical MgO-NPs with an average size of 20.38 ± 9.9 nm. The potentiality of MgO-NPs was dose- and time-dependent. The biogenic MgO-NPs was found to be a promising antimicrobial agent against the pathogens including Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans with inhibition zones of 10.6 ± 0.4, 11.5 ± 0.5, 13.7 ± 0.5, 14.3 ± 0.7, and 14.7 ± 0.6 mm, respectively, at 200 μg mL–1. Moreover, MgO-NPs manifested larvicidal and adult repellence activity against Culex pipiens at very low concentrations. The highest decolorization percentages of tanning effluents were 95.6 ± 1.6% at 100 µg/ 100 mL after 180 min. At this condition, the physicochemical parameters of tannery effluents, including TSS, TDS, BOD, COD, and conductivity were reduced with percentages of 97.9%, 98.2%, 87.8%, 95.9%, and 97.3%, respectively. Moreover, the chromium ion was adsorbed with percentages of 98.2% at optimum experimental conditions. [ABSTRACT FROM AUTHOR]

Several tannery effluent treatments were studied, but there was no process that could remove the total pollution of these effluents. Besides, most of those processes are expensive. In this study, a promising coupled treatment of tannery effluents was performed to eliminate the entire pollution load of these toxic effluents. The treatment of these effluents was by precipitation using ferric chloride coupling with the sequencing batch reactor (SBR) process. For the SBR system, a daily cycle treatment and a high organic load of 1.5 kg of COD d-1 m-3 were used. Concerning the results, this combined system provided very satisfactory outcomes, wherein removals were 99.89%, 99.98%, and 99.99%, respectively, for the chemical oxygen demand (COD), the sulfide ions, and the total chromium. Thus, the treated effluent is strongly conformed to the Moroccan standard of discharge. This result was not reached when these two systems were applied separately in previous studies. Therefore, this combined treatment can be an attractive and economic treatment for tannery effluent treatmen [ABSTRACT FROM AUTHOR]

The increase of anthropogenic activities has led to the pollution of the environment by heavy metals, including chromium (Cr). There are two common oxidative states of Cr that can be found in industrial effluents the trivalent chromium Cr(III) and the hexavalent chromium Cr(VI). While the hexavalent chromium Cr(VI) is highly toxic and can trigger serious human health issues, its reduced form, the trivalent chromium Cr(III), is less toxic and insoluble. Leather tanning is an important industry in many developing countries and serves as a major source of Cr(VI) contamination. Globally, tannery factories generate approximately 40 million m3 of Cr-containing wastewater annually. While the physico-chemical treatments of tannery wastewater are not safe, produce toxic chemicals and require large amounts of chemical inputs, bioremediation using chromium-resistant bacteria (CRB) is safer, efficient and does not produce toxic intermediates. Chromium-resistant bacteria (CRB) utilise three mechanisms for Cr(VI) removal: biotransformation, biosorption and bioaccumulation. This review will evaluate the three Cr(VI) detoxification mechanisms used by bacteria, their limitations and assess their applications for large-scale remediation of Cr(VI). This can be helpful for understanding the nature of Cr(VI) remediation mechanisms used by bacteria, therefore, bridging the gap between laboratory findings and industrial application of microorganisms for Cr(VI) removal. [ABSTRACT FROM AUTHOR]

In Arequipa (Peru), a small-scale tannery industry cannot afford costly or complicated methods for effluent treatment. In this work, we designed and tested a bubble column bioreactor for tannery effluent treatment based on the native filamentous fungi Penicillium citrinum and Trichoderma viride. The bioreactor construction used low-cost materials, with an easy-to-handle design. The parameters considered for testing were based on current Peruvian legislation. In the bioreactor, P. citrinum successfully reduced the effluent content of sulfides, chemical oxygen demand (COD) and total suspended solids (TSS) and removed nearly 80% of the chromium (VI) after 120 h of reaction. The resulting treated effluent had a composition within the maximum limits permitted by Peruvian legislation. Trichoderma viride also reduced the content of TSS, COD and sulfides, but decreased the chromium (VI) concentration by only ~ 20% after the same reaction time. Both filamentous fungi were able to grow in the experimental conditions used and the bioremediation process occurred with no significant alteration in pH. These findings indicate that a bubble column bioreactor using P. citrinum as a bioremediator agent provides low-cost, effective technology for treating effluent waste produced by artisanal and small-size tannery factories in the region of Arequipa. [ABSTRACT FROM AUTHOR]

This work is the first attempt to evaluate suitability of Callitriche cophocarpa Sendtn. (water-starwort) to remove Cr under real-world conditions. Our earlier laboratory-scale studies demonstrated outstanding hyperaccumulation properties of this aquatic higher plant (macrophyte) toward chromium in solution. We introduced C. cophocarpa plants into the watershed with sediments heavily polluted (on average 1400 mg/kg d.w. of Cr) by a tannery. The plants grew vigorously and exhibited no physiological or anatomical disorders. Based on chemical fractionations of bottom sediments, we found low Cr bioavailability. The element was strongly associated with the sediments and could be classified into the following fractions (%): oxidizable III (68.2) > residual IV (28.8) > reducible II (1.6) > exchangeable I (1.4). Despite this, Cr content in plant organs at the contaminated sites was 33 up to 83 times greater than in the control leaf/stem and roots, respectively. Altering redox potential during, i.e., sediment deposition on land may change chemical forms of bound metals in a solid phase, and thus further increase Cr phytoextraction by plants. With this in mind, we concluded that the species, being an outstanding Cr accumulator under laboratory conditions, can be useful in the reclamation of Cr-polluted sediments under controlled, oxidizing conditions. [ABSTRACT FROM AUTHOR]

The tanning industry is the major ehromium eonsuming industry. Tanning industries are present throughout Pakistan, but their presenee is more eoneentrated in small industrial eity Sialkot. The samples of wastewater were eolleeted from different tanneries and Nullah Aik whieh are situated in Sialkot and analyzed for the measurement of pollution level. The effluents sample demonstrated high values of temperature (32-42°C), pH (5.1-10.9), biologieal oxygen demand (335-5818 mg/L), ehemieal oxygen demand (740-14546 mg/L), total solids (2265-19314 mg/L), total dissolved solids (1313-17467 mg/L), hexavalent ehromium (1.8-9.8 mg/L), and total ehromium (3.75-16.7 mg/L). The total ehromium analyzed by atomie absorption speetrometry and hexavalent ehromium determined by UV-Visible Speetrophotometer with DCP. The study foeused on the level of pollution in tannery wastewater to estimate the impairment eaused by them. [ABSTRACT FROM AUTHOR]

The present study aimed that non-toxic, less expensive, easily available, safer to environment and previously unreported Eclipta prostrata leaf extract is used for the green synthesis of iron oxide nano particles. The iron oxide nanoparticles (NPs) were characterised by UV–visible, Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tannery effluents treated by photodegradation process and the removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD) and sulphide were analysed. The maximum removal efficiency correlated with operating parameters was explained using response surface methodology with Boxmen Beckmen design. [ABSTRACT FROM AUTHOR]

Tannery-effluent is one of the top-ranked hazardous waste which is generally discharged into the river. To study the fluvial response toward the tannery-effluents and to trace anthropogenic foot-prints in the fluvial-system, a suite of systematically collected sediment and water samples were analyzed for radioactive (226Ra, 232Th, and 40K) and non-radioactive elements (Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, and Pb). Neutron activation analysis and atomic absorption spectroscopy were used for elemental analysis, whereas HPGe-gamma-detector was used for measuring the primordial-radionuclides. Ranges of Cr-abundances in sediment and water were 63–4373 μg.g−1 and 15.6–52.2 μg.L−1, respectively which were ∼4–14 times higher than the geological background. Radioactivity concentrations of 226Ra, 232Th, and 40K ranged from 17.7–48.5, 36.1–81.6, and 687–1041 Bq.kg−1, respectively which were significantly depleted in effluent discharge point. Hence, primordial-radionuclides were used as natural tracers for tracing anthropogenic foot-prints which were explained in terms of dilution effect, redox environment and differential geo-environmental events/characteristics. From statistical-approaches and geochemical reasoning, elemental sources and responses in fluvial system were explored. Surprisingly, ecological & radiological risks were reduced while sediment quality guideline-based ecotoxicity & water-mediated health risks were increased by the incorporation of tannery effluents. This study describes the sedimentary response toward the received tannery effluents which is particularly explored by the primordial radionuclides. [Display omitted] • 226Ra, 232Th, and 40K are used as tracer to trace the anthropogenic footprints. • Cr-content is upto 14-times higher than the sediment quality guidelines. • Radionuclide contents were depleted in response to the tannery effluent's influx. • Dilution effect & redox environment control the degree of NORMs' alterations. • Ecological, ecotoxicological, radiological & health risks alteration were observed. [ABSTRACT FROM AUTHOR]

NOTE: on 21st May 2015, the authors Mahmud Hossain and M Mohasin were added to the online information about the article. The PDF remains correct.In this study the physicochemical and biochemical qualities of the tannery effluents were analyzed to determine the pollution load of the openly released wastewaters in the environment and the findings were compared with the non-tannery waters. Fourteen samples of factory effluents were collected from the leather tanning industrial zone of Hazaribagh, Dhaka, and 13 non-tannery water samples were collected from different parts of Dhaka city. The effluents were mostly colored; their pH varied from highly acidic to basic values while densities were not much different from the non-tannery waters. The chromium contents of the effluents varied from less than 0.002 to 18.97 mg/L and the chemical oxygen demands (COD) varied from 90 to 6500 mg/L, which were significantly higher than those of non-tannery waters. There was a strong direct correlation between chromium content and COD (pDOI: http://dx.doi.org/10.3126/ije.v4i1.12179International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15, page: 68-81

Abstract: This study reports the development of a functional adsorbent synthesized by the molecular imprinting method in a sol–gel matrix. The adsorption capacity of the organic-inorganic hybrid adsorbent material was tested on tannin compounds, i.e., phenolic substances that are among the most difficult compounds to remove in industrial wastewater. The specific surface area obtained by nitrogen porosimetry analysis was between 2 and 579 m2 g−1 due to each sol–gel synthetic route used. Small-angle X-ray scattering analysis revealed that the hybrid silicas were arranged in a multi-level structure consisting of three levels of organization and a surface fractal structure. Diffuse reflectance spectroscopy revealed the interactions between the tannins and the silica matrix, and confirmed the partial removal of tannins after ultrasound-assisted extraction. Zeta potential analysis showed that the values ranged between −37.9 and +27.8 mV, where non-functionalized xerogels were anionic and those functionalized with organosilane were cationic. The structural and textural characteristics of the hybrid materials were found to depend on the sol–gel synthetic route, which in turn affected the adsorption capacity. The adsorbent functionalized with (3-Aminopropyl) triethoxysilane was an effective adsorbent for the tannin compounds tested here, with approximately 90% removal in aqueous solutions.Graphical abstract: [ABSTRACT FROM AUTHOR]

The levels of hexavalent chromium from direct and treated Sheba tannery effluents, downstream river and spring water samples and upstream river water samples were determined spectrophotometrically by the s-diphenylcarbazide method at 540 nm. Temporal and representative samples were collected from the untreated tannery effluent (S1), sedimentation pond (S2), chromium oxidation pond (S3), downstream river (S4), downstream spring (S5) and 5 kms upstream river (S6). The mean levels of hexavalent chromium in S1, S2, S3, S4, S5 and S6 were 10.54, 9.15, 7.82, 0.58, 0.54 and 0.015 mg/L, respectively. The levels of hexavalent chromium in the downstream river and spring water samples exceed the World Health Organization (WHO) permissible limit of total chromium in drinking waters (0.05 mg/L) as opposed to the levels in the upstream waters. The increased concentrations of Cr(VI) in the water samples indicate the possible environmental pollution of the downstream water bodies by the Sheba tannery effluents. In view of the toxicity and related environmental hazards, the levels of hexavalent chromium from the Sheba tannery effluents must be reduced to a permissible limit before discharging into the down stream waters being used for domestic purposes by the nearby communities.

Globally, the leather industry is currently undergoing radical transformation due to pollution and discharge legislations. The present study is based on the investigation of performance of a hybrid electrocoagulation/electrodialysis process for the removal of COD, NH 3 -N, Cr and color in tannery wastewater. Effects of current density and electrolysis time were analyzed to optimize the electrocoagulation process with aluminum either iron electrodes. The optimized electrocoagulation process was then integrated with electrodialysis (ED) for the treatment of tannery effluents and was found that the hybrid process was capable of promoting the quality of the treated tannery wastewater. In case of treated tannery by EC with aluminum electrodes, ED process was effectiveness where the removal efficiency of COD, NH 3 -N, Cr and color were 92,100,100,100% respectively corresponds to conductivity value of 0.371 mS/cm at 45 minute. While, in the case of treated tannery by EC with iron electrodes, ED process was also efficient for removal pollutants, the removal efficiency of COD, NH 3 -N, Cr and color were 87,100,100,100% respectively corresponds to conductivity value of 1.5 mS/cm at 75 minute. It is noticeable that the effluent treated with combined EC-ED techniques presents very similar values for the same parameter as the ones presented by normal feed water. [ABSTRACT FROM AUTHOR]

This study presents an overview of the existence and effects of six heavy metals, chromium (Cr), lead (Pb), cadmium (Cd), mercury (Hg), manganese (Mn), and aluminum (Al), in tannery effluents released to the Buriganga River in Dhaka, Bangladesh. The pollutants were found in three different sources, such as effluents from tanneries, contaminated river water and three species of fish—climbing perch (Anabas testudineus), spotted snakehead (Channa punctata), and Black tilapia (Oreochromis mossambicus) caught from the river. Tannery effluents, water, and fish samples were collected from three different factories, five sample stations, and three different harvesting points, respectively. Effluents from all three factories contained significant amounts of heavy metals, especially Cr (374.19 ppm in average), whereas lesser amounts were found in the tissues of the three fish species studied. The trends in tissue elemental concentrations of fish were Cr > Pb > Al > Hg > Mn > Cd. In most cases (Cr, Cd, Mn, and Al), heavy metal concentrations were found to be greater in climbing perch than in Black tilapia and spotted snakehead. Although the river water contained high concentrations of harmful heavy metals, the fish species under study had concentrations well below the permissible Food and Agriculture Organization/World Health Organization levels for those metals and seemed to be safe for human consumption. [ABSTRACT FROM AUTHOR]

Chrome tanning activity has contributed intensively towards environmental pollution in the form of effluents. To study the specific contribution of microalgae towards phycoremediation, four heavy-metal tolerant microalgal species were isolated from the estuaries receiving tannery effluents, and their biomass was examined by their interaction. The sequences of the four microalgal species, namely Anabaena (VITMA1), Oscillatoria acuminate (VITMA2), Phormidium irriguum (VITMA3) and Spirogyra maxima (VITMA4), were clustered after isolating their ribosomal DNA. Phylogenetic analysis revealed that VITMA1 showed a distant relationship with Anabaena , having only 63% sequence similarities, and other species such as VITMA2, VITMA3 and VITMA4 showed 82%, 95% and 92% sequence similarities, respectively. Microalgal species were grown in BG11 media along with chromium-contaminated tannery effluents for analysing their growth, biomass and protein contents. The binding site characterisation was assessed by Fourier transform infrared spectroscopy, nuclear magnetic resonance and X-ray diffraction spectral studies. The results obtained from these studies advocate that the interactions are due to the presence of alkynes and aromatic functional groups. Scanning electron microscopy analysis showed the presence of intact cells with chromium accumulation. The biosorption activity was found to be 90% for O. acuminate (VITMA2), followed by 80% for P. irriguum (VITMA3), 65% for Anabaena (VITMA1) and 55% for S. maxima (VITMA4), respectively, and proves their impressive potential for phycoremediation activity. [ABSTRACT FROM AUTHOR]

In this study, the treatment of the effluents of an artisanal tannery by electrocoagulation with iron electrodes was carried out. During electrolytic treatment, a current intensity of 0.4 A was used, and the electrolysis time was varied from 0 to 40 minutes. The performance of electrocoagulation was compared with that of chemical coagulation with ferric sulfate. The results obtained showed that highest removals after electrocoagulation were 71.15, 98.26, and 86.59% for the COD, colour and turbidity respectively. Chemical coagulation reduced the COD up to 83.17%, while colour and turbidity removals were 99.81 and 98.62% respectively. Although chemical coagulation leads to highest percentage removals after treatment, electrocoagulation results in near neutral pH values and also decrease conductivity weakly. By contrast, chemical coagulation increases the acidity of the effluent and its conductivity. Hence with close to neutral pH and weak conductivity values obtained for effluents treated by electrocoagulation, it is inferred that such treated effluents can be recycled. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)