Tannery Sludge Research Articles

Fractionation and risk assessment of metals in sediments of an ocean dumping site

Sediments of Yellow Sea dumping sites (YSDS) collected in 2015 were analyzed using the European Community Bureau of Reference (BCR) sequential extraction method to assess the contamination and potential risk to the environment. Cr, Ni, Cu, and Zn exhibited the most dominant residual fraction, whereas Cd was mostly in the exchangeable fraction and Pb in the reducible fraction. Cr contains a significant amount of oxidizable fraction in the dumping area due to the dumping of tannery sludge with high concentrations of Cr, mainly in the organic matter-bound form. The global contamination factor (GCF) showed that high non-residual fractions of Cd and Pb contributed considerably to contamination. Nevertheless, modified potential ecological risk index (MRI) suggested low ecological risk for metals in YSDS because of the low total content of Cd and the small mobile fraction of other metals.

Soil Pollution Characteristics and Microbial Responses in a Vertical Profile with Long-Term Tannery Sludge Contamination in Hebei, China.

An investigation was made into the effects of tannery sludge on soil chemical properties and microbial communities in a typical soil profile with long-term tannery sludge contamination, North China. The results showed that trivalent chromium (Cr(III)), ammonium, organic nitrogen, salinity and sulfide were the predominant contaminants in tannery sludge. Although the tannery sludge contained high chromium (Cr, 3,0970 mg/kg), the proportion of mobile Cr forms (exchangeable plus carbonate-bound fraction) only accounted for 1.32%. The X-ray diffraction and X-ray photoelectron spectroscopy results further demonstrated that the Cr existed in a stable state of oxides and iron oxides. The alkaline loam soil had a significant retardation effect on the migration of salinity, ammonium, Cr(III) and sulfide, and the accumulation of these contaminants occurred in soils (0–40 cm). A good correlation (R2 = 0.959) was observed between total organic carbon (TOC) and Cr(III) in the soil profile, indicating that the dissolved organic matter from sludge leachate promoted the vertical mobility of Cr(III) via forming Cr(III)-organic complexes. The halotolerant bacteria (Halomonas and Tepidimicrobium) and organic degrading bacteria (Flavobacteriaceae, Tepidimicrobium and Balneola) became the dominant microflora in the soil profile. High contents of salinity, Cr and nitrogen were the main environmental factors affecting the abundance of indigenous microorganisms in soils.

Anaerobic Digestion of Secondary Tannery Sludge: Optimisation of Initial pH and Temperature and Evaluation of Kinetics

The feasibility of retrofitting and operating a low cost anaerobic mesophilic batch reactor for the reduction of secondary tannery sludge (STNS) produced in tannery wastewater treatment plants at varying initial reactor pH (pHin) using acclimated inoculum was demonstrated using the bio-methane potential test protocol. Temperature had a significant effect on process indicators whilst the effect of pHin was negated by the STNS’ high alkalinity and its buffering capacity offered by ammonia/ammonium speciation, eliminating the need for pH control during digestion. Furthermore, there was an insignificant and significant variation in the biodegradability (Bo) and gas yields of STNS, respectively. This nullified the need for reactor heating if gas yields were not prioritised. Nonetheless, optimum conditions (35.5–37.0 °C and pHin 6.5) yielded 200–217 mL biogas/gVS (≈ 55% CH4), 108–118 mL CH4/gVS and 69–74% VS, 54–57% TS and 47–48% COD reduction. Cumulative CH4 generations were accurately modelled using the modified Gompertz, Logistic, First order, Cone (0.828 ≤ Adj R2 ≤ 0.986) and process kinetics were determined. However, the correlations between kinetics and process parameters were mostly non-monotonic. The positive effect of temperature on A (r = 0.84) coincided with a decrease in methanogenesis rate (k) and ratio of hydrolysis and methanogenesis (K/µm) at optimum pHin signifying an inhibited steady state reactor condition.

Screening of most potential candidate among different lemongrass varieties for phytoremediation of tannery sludge contaminated sites

One of the most sustainable approaches for reclamation of heavy metal contaminated sites is by phytoremediation. Cultivation of aromatic plants in such areas has been proposed by a number of researchers as it fulfills the purpose of phytoremediation alongside monetary benefits. A pot experiment was conducted to screen out most potential candidate among different lemongrass varieties which can be recommended to be grown in tannery effluent contaminated sites. Four consecutive harvests of nine varieties of lemongrass were tested. Translocation factor (TF) < 1 for chromium and cadmium whereas >1 for nickel and lead was observed in all varieties. Bioconcentration factor (BF) > 1 was observed for chromium in Suwarna variety. Photosynthetic pigments, growth parameters, antioxidants, oil content, and yield were highly correlated. Neighbor joining (NJ) cluster analysis was performed to predict the relationship between varieties according to their chromium uptake potential. Endurance of varieties towards metal stress was assessed using chlorophyll a fluorescence kinetics. Maximum reduction potential of chromium (70.07%), lead (85.29%), and cadmium (77.36%) was observed in Suwarna variety. Our study indicated that lemongrass acts as potential phytoextractor for nickel and lead. Suwarna variety appeared to be the best candidate among all the varieties tested owing to its higher biomass and metal uptake potential.

Characterization studies of tannery sludge, flyash and GGBS

Characterization studies of tannery sludge, flyash and GGBS

Nodulation, nitrogen uptake and growth of lima bean in a composted tannery sludge-treated soil

ABSTRACT: This study evaluated the responses of lima bean (Phaseolus lunatus L.) to application of composted tannery sludge on nodulation, N uptake and plant growth. For eight years, the compost was applied at rates of: 0, 2.5, 5, 10, and 20 Mg ha-1 (dry basis). Plants of lima bean showed higher nodulation in treatments with compost; however, nodules reported in these treatments presented lower biomass, size and diversity than those reported in treatment without compost. Accumulation of N increased with the application of the highest rate (20 Mg ha-1), while there was an increase in chromium content in shoot with the increase in compost rates. Thus, the use of composted tannery sludge, in long-term, increases the accumulation of chromium in plants, increasing nodulation, while decrease rhizobia diversity in nodules.

Utilization of multi-metal laden spent biosorbent for removal of glyphosate herbicide from aqueous solution and its mechanism elucidation

Extensive uses of glyphosate herbicide pose the environmental concerns of surface and ground water contaminations through leaching. The present investigation is based on potential reuse of multi-metal laden spent biosorbent for glyphosate removal. Our previous study showed effective removal of Ni(II), Co(II), Zn(II) and Cd(II) ions in multi-metal system using waste activated sludge from tannery industry as biosorbent. Glyphosate biosorption efficiency of the waste tannery sludge was enhanced from 26.18% to >92% after increase in the multi-metal loading on the sludge. Feasibility study for actual wastewater treatment showed about 91.7% removal of glyphosate in the simulated agricultural runoff. The glyphosate biosorption exhibited gradual removal process. The rapid 70–75% biosorption was attained in first 2 h of contact time and the final removal of 89–94% was achieved within 24–28 h of contact time. Equilibrium isotherm and kinetics data were obtained by adsorption experiments. Biosorbent characterization and removal mechanism were established. The formation of glyphosate-metal complexation was confirmed by the FTIR, XPS, XRD, XRF, FESEM-EDAX and elemental mapping results. Surface bound multi-metals of the biosorbent could predominantly form mononuclear, bi-, tri- or tetra-dentate complexes through phosphonate group of glyphosate molecule. Weak binding of glyphosate molecule with the carboxyl and amino groups also occurred. The glyphosate loaded biosorbent were successfully inertized up to 10 wt% in phosphate glass matrix as confirmed by XRD for safe disposal of the toxic sludge in the environment.

Do environmentally induced DNA variations mediate adaptation in Aspergillus flavus exposed to chromium stress in tannery sludge?

BackgroundEnvironmental stress induced genetic polymorphisms have been suggested to arbitrate functional modifications influencing adaptations in microbes. The relationship between the genetic processes and concomitant functional adaptation can now be investigated at a genomic scale with the help of next generation sequencing (NGS) technologies. Using a NGS approach we identified genetic variations putatively underlying chromium tolerance in a strain of Aspergillus flavus isolated from a tannery sludge. Correlation of nsSNPs in the candidate genes (n = 493) were investigated for their influence on protein structure and possible function. Whole genome sequencing of chromium tolerant A. flavus strain (TERIBR1) was done (Illumina HiSeq2000). The alignment of quality trimmed data of TERIBR1 with reference NRRL3357 (accession number EQ963472) strain was performed using Bowtie2 version 2.2.8. SNP with a minimum read depth of 5 and not in vicinity (10 bp) of INDEL were filtered. Candidate genes conferring chromium resistance were selected and SNPs were identified. Protein structure modeling and interpretation for protein-ligand (CrO4− 2) docking for selected proteins harbouring non-synonymous substitutions were done using Phyre2 and PatchDock programs.ResultsHigh rate of nsSNPs (approximately 11/kb) occurred in selected candidate genes for chromium tolerance. Of the 16 candidate genes selected for studying effect of nsSNPs on protein structure and protein-ligand interaction, four proteins belonging to the Major Facilitator Superfamily (MFS) and recG protein families showed significant interaction with chromium ion only in the chromium tolerant A. flavus strain TERIBR1.ConclusionsPresence of nsSNPs and subsequent amino-acid alterations evidently influenced the 3D structures of the candidate proteins, which could have led to improved interaction with (CrO4− 2) ion. Such structural modifications might have enhanced chromium efflux efficiency of A. flavus (TERIBR1) and thereby offered the adaptation benefits in counteracting chromate stress. Our findings are of fundamental importance to the field of heavy-metal bio-remediation.

UTILIZAÇÃO DE LODO DE ESTAÇÃO DE TRATAMENTO DE ÁGUA RESIDUÁRIA DE CURTUME NOS PARÂMETROS MICROBIOLÓGICOS DO SOLO

The present work has the objective of evaluating the microbiological properties of the soil that presents increasing doses of tannery sludge. The experiment was carried out under greenhouse conditions, located at Campus II - UNOESTE, in the city of Presidente Prudente. The application of different doses of tannery sludge in microbiological soil parameters was evaluated. The study was conducted in 30 pots of 10 kg during the period of one hundred days, after which samples were collected and sent to the laboratory for the soil biological evaluations of carbon and nitrogen of the microbial biomass and basal respiration of the soil. The data were submitted to analysis of variance, and the comparison was made by regression. The application of the dosage of 2 Mg of sludge ha-1 under the soil surface allowed an increase in the carbon and nitrogen of the microbial biomass being efficient. Higher dosages end up reducing the elements in the biomass.

Removal of toxic pollutants using tannery sludge derived mesoporous activated carbon: Experimental and modelling studies

Safe disposal of tannery activated sludge is a major challenge faced due to its complex nature. The present work focuses on the conversion of the tannery sludge biomass into mesoporous nano-activated carbon through carbonization and physical activation methods The prepared material was characterized by FE-SEM, EDAX, FT-IR, TGA, surface area, pHZPC and surface functionality. The biomass derived activated carbon possesses specific surface area, mean pore diameter, total pore volume and zero point charge of 187.21 m2/g, 3.24 nm, 0.152 cm3/g and 7.80 respectively. The adsorbent was used for the removal of Malachite Green (MG), hexavalent chromium (Cr(VI)) and 2,4-Dichlorophenoxyacetic acid (2,4-D) from aqueous phase. Preliminary studies on the effect of pH, adsorbent load, concentration, kinetics of adsorption and adsorption dynamics were optimized using Response Surface methodology (RSM). Analysis of variance (ANOVA) showed high values of determination coefficient (R2) for the three pollutants. viz., MG dye (R2 = 0.9914), Cr (VI) (R2 = 0.9882) and 2,4-D (R2 = 0.9838). The monolayer adsorption capacity of the adsorbent was 231.34 mg/g, 86.26 mg/g and 20.09 mg/g, respectively for MG, Cr(VI) and 2,4-D. The adsorption data fitted well with Langmuir isotherm and the kinetics followed the pseudo second order model. The thermodynamic studies showed the adsorption process to be endothermic, spontaneous and favourable.

Effective bioremediation and toxicity assessment of tannery wastewaters treated with indigenous bacteria.

This study evaluated the bioremediation capacity of indigenous bacteria isolated from tannery sludge for two different tannery wastewaters collected from Kanpur and Chennai. To identify bacteria which can efficiently degrade a mixture of different pollutants, the isolates were grown in hazardous 100% tannery wastewaters. The reductions in toxicants such as chromium, sulphate, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the wastewater were analysed post-bioremediation. Amongst the isolates, Citrobacter freundii was able to reduce the concentration of multiple toxicants such as chromium by 73% and sulphate was reduced by 68% bringing down the level much below the permissible limit stipulated by Bureau of Indian Standards (BIS). Notably, the organic load characterized by BOD and COD was also lowered by 86 and 80%, respectively. The indigenous isolates, not only bioremediated the Kanpur effluent but, also significantly detoxified the Chennai effluent having higher toxicant load. An interesting observation made during the study was better survival and growth along with the development of appendages of Artemia nauplii in the treated wastewaters which thus further confirmed reduction in toxicity of the effluents. The results thus demonstrate that the tested indigenous strains are promising for bioremediation of tannery wastewater and effectively improve the water quality for safe discharge.

Formulation and durability of a geopolymer based on metakaolin/tannery sludge

In this study, tannery sludge was used as a partial replacement material for a geopolymer. The best raw material composition of the geopolymer and durability of the solidified product were studied. Solidification effect was analyzed via compressive strength and total concentration of chromium leached. Its durability in terms of high-temperature resistance, acid/base resistance property, and resistance to acid rain erosion was studied. Through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric Differential Thermal Analysis (TG-DTA) and scanning electron microscopy (SEM), the compressive strength and total concentration of chromium leached in different environments were analyzed. The results show that the mechanical properties of the solidified product were optimal when the silica/alumina mole ratio and sodium oxide/silica mole ratio were 2.45 and 0.37, respectively. The optimal raw material ratio of the above-mentioned product was used to synthesize a geopolymer containing 20% tannery sludge, with the solidified product showing high durability, as indicated by its good high-temperature resistance, high resistance to acids and alkalis, and great resistance to acid rain erosion.

Activated carbon (prepared from secondary sludge biomass) supported semiconductor zinc oxide nanocomposite photocatalyst for reduction of Cr(VI) under visible light irradiation

Activated carbon prepared from waste tannery sludge biomass was employed in the synthesis of carbon supported ZnO photocatalyst (ZnO-SBAC). Different ratios of ZnO-SBAC (ZC) were synthesized by hydrothermal method. The prepared materials were characterized thoroughly. From the UV–vis-DRS data, zinc: carbon 2:3 ratio (ZC-2:3) was found to have lower band gap energy of 2.96 eV compared to other ratios. FE-SEM analysis revealed the ZnO flakes to lie on the surface of the carbon. The prepared ZC-2:3 nanocomposites has higher surface area of 216.35 m2/g compared to pristine ZnO 11.60 m2/g. The in-situ generation of OH radicals was detected by EPR analysis. The prepared ZC nanocomposite material was employed as a visible active photocatalyst for the reduction of Cr(VI) ions. Among the prepared ratios, ZC-2:3 exhibited the highest activity. The preliminary photocatalytic studies showed acidic medium (pH 2.25) and a catalyst dosage of 10 mg/10 mL to be optimum. The kinetic studies showed the photo reduction of Cr(VI) using pristine (P-ZnO) and ZnO-SBAC to follow pseudo-first order kinetics. The effect of adsorption (dark reaction) was investigated using Langmuir and Freundlich isotherms. ZC has better adsorption capacity (3.54 mg/g) compared to P-ZnO (0.76 mg/g) which may increase the photoreduction of Cr(VI) ions. The ZC-2:3 nanocomposite showed better reusability photocatalyst without affecting its performance up to three cycles when compare to P-ZnO. The prepared ZnO-SBAC exhibits good synergetic effect of adsorption followed by photoreduction for the conversion of Cr(VI) to Cr(III).

Less abundant bacterial groups are more affected than the most abundant groups in composted tannery sludge-treated soil

The application of composted tannery sludge (CTS) has promoted shifts in soil chemical properties and, therefore, can affect the soil bacterial community. This study assessed the effect of the CTS on the soil bacterial community over time. The CTS was applied at five rates (0, 2.5, 5, 10 and 20 t/ha), and the bacterial community was evaluated for 180 days. The principal curve response (PRC) analysis showed that the most abundant phyla were not influenced by the CTS rates over time, while the analysis of the bacterial community showed that some of the less abundant phyla were influenced by the CTS rates. Similarly, the PRC analysis for the bacterial classes showed the significant effect of the CTS rates. The redundancy analyses for the bacterial phyla and classes showed the relationship between the significant chemical properties and the bacterial community of the soil after the CTS amendment over time. Therefore, there was a shift in the bacterial community over time with the application of the composted tannery sludge. Our study has shown that the less abundant bacterial groups were more influenced by the CTS than the most abundant bacterial groups and that these bacterial groups were driven by soil chemical properties, primarily chromium (Cr) and the soil pH.

Use of Sludge Waste as Ingredient in Making of Brick

Waste may be defined as an unwanted material generated after the manufacturing process from industry, agriculture, or from house hold activity. Waste causes many nuisances in the environment. It produces many types of infection, for human and animal. The sludge from tannery effluent plants has problem of disposal. Dewatered sludge is disposed off by land filling. However, it is not an appropriate solution, due to the land limitation. The production of sludge in tannery effluent plant is about to increase every year. In addition, the constraint to treat sludge is very high in cost and time-consuming, which is the disadvantage to the responsible parties. Therefore, this study was carried out to utilize those sludge waste (SW) produced from the tannery effluent plant as a brick. The sludge brick (SB) mixtures were incorporated with many ratios of SW. Tests were conducted such as fineness test, specific gravity, water absorption and compressive strength. As the conclusion, brick with 20% utilization of SW is acceptable to produce good quality of brick. This study shows that the disposal of tannery sludge TSW would act as a suitable material for manufacturing of bricks with proportionate mix and design.

Detoxification of chromium-rich tannery industry sludge by Eudrillus eugeniae: Insight on compost quality fortification and microbial enrichment

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.

Performance evaluation of saponin over other organic acid and tap water for removal of chromium in tannery sludge by electrokinetic enhancement

ABSTRACTThe performance of Saponin over different electrolyte-mediated electrokinetic (EK) process for removal of Cr(III) from tannery sludge was assessed. Saponin exhibited maximum Cr(III) removal efficiency, i.e. 67.6–80.75% as compared to other groups of processing fluids. The possible mechanistic approach for the highest removal efficiency of saponin over other electrolytes may be attributed to synchronized effect of micelle formation and subsequent complexation and sorption of chromium ions. The highest electroosmotic flow rate of saponin indicated low electroosmotic resistance during EK process, which validates the observed trend. Therefore, saponin can be considered as a promising electrolyte for EK treatment of tannery sludge.Abbreviation: CA: Citric acid; LA: lactic acid; OA: oxalic acid; BOD: biochemical oxygen demand; COD: chemical oxygen demand; EK: electokinetic.

Experimental Studies on Solidification and Stabilization of Tannery Sludge

Experimental Studies on Solidification and Stabilization of Tannery Sludge

Effect of Substrate Treated with Tannery Sludge on Growth and Anatomy of Conilon Coffee Cuttings

Effect of Substrate Treated with Tannery Sludge on Growth and Anatomy of Conilon Coffee Cuttings

Substrate Stabilization Using Humus with Tannery Sludge in Conilon Coffee Seedlings

Substrate Stabilization Using Humus with Tannery Sludge in Conilon Coffee Seedlings