Chromium In Effluents Research Articles

Risk Assessment of Hydrogen Sulfide (H₂S) Gas and Its Impact on Human Health: Evidence from Tannery Industry of a Developing Country

Hydrogen sulfide (H₂S) gas is quite risky and harmful for the tannery industry workers in Bangladesh. A proper measurement or assessment of this risk will help policymakers make crucial policy decisions, which will surely help the continued positive growth of this industry. This study has three specific objectives: identifying potential sources of hydrogen sulfide gas generation, assessing the root causes of hydrogen sulfide gas generation, and suggesting proper activities to reduce the impact of hydrogen sulfide gas generation. In order to carry out this study, a qualitative approach has been used, where qualitative data are used to find out the results. It started with reviewing the secondary documents but also included key informant interviews (KIIs), focus group discussions (FGDs), and a sample survey. This study has collected data from 20 different tanneries. Out of 20 tanneries, 80 respondents were selected via the purposive sampling method. Information has been taken from 80 respondents via Key Informant Interviews and Focused Group discussions, where each group consists of a different number of individuals and is selected on the basis of the location of the production process in tanneries. The study has found major sources and causes of H₂S generation. The major sources include the tanning chemical store, pre-tanning (Beam house area), Re-tanning area, Chrome effluent drain, Mix effluent drain, etc. The major causes of H₂S gas generation include intermixing of incompatible chemicals, lack of proper cleanliness, reaction of liming liquors, etc. The study also suggested various measures such as proper ventilation, separating chromium and re-tanning effluent from alkaline effluent, and reducing solid waste.

Recovery and Reuse of Chromium from Tannery Waste Chrome-liquor using Solar Evaporation Process

Recovering and reusing chrome from chrome effluent is critical for improving the mass balance of the tanning process and implementing the zero liquid discharge concept in the tanning industry. Conventional chrome recovery methods require a large amount of chemicals or energy to recycle the chromium. Chrome recovery by solar evaporation has not been implemented yet in the tanning industry. It is mainly practised in seawater salt extraction. In this study, we demonstrate the construction of highly efficient solar evaporators, using photothermal materials. Our focus is on efficient solar-to-vapour conversion and chrome recovery. The average evaporation rate was calculated and found 38.69 mL/hour, which remained almost steady within 2.5 months of data collection. The highest temperature observed during the process was 108 °C and 62°C in the focal region and condenser respectively. After collecting the solid chromium, basicity was measured at 85.02%, and treated with sulphuric acid to achieve 33% basicity. Recovered chrome and fresh chrome at 0:8, 5:3, and 8:0 were used for chrome tanning and tested for various chemical and physical parameters of tanned leather. The shrinkage temperature of the produced leather was found to be more than 100 °C. Physical characteristics such as tensile strength and percentage of elongation test, stitch tear strength, ball bursting strength and flexing endurance showed better results than conventional methods. This new kind of research offers a promising solution that can reduce the environmental impact of the tanning industry while also providing a sustainable source of chromium for a low-cost strategy and high-performance evaporation approach.

A continuous process in mixers-settlers for the removal/recovery of chromium in effluents from the tanning industry.

One of the main environmental issues caused by the tanning industry is given by the high concentration of chromium contained on its effluents. The removal of this pollutant has become a technological challenge. To solve this issue, this work proposes a continuous process based on mixers-settlers for the removal of the chromium present in effluents from the tanning industry. The process involves the use of liquid-liquid extraction systems. The study includes the development of isotherms for the removal and stripping, which are further represented through a mathematical model to determine the number of theoretical extraction stages and other operational variables. The results show that a better extraction is achieved in a system with two theoretical stages using Cyanex 272 as extractant, reaching more than 94% of removal of chromium with an extractant concentration of 0.32 mol/L. For stripping, sulfuric acid is used, obtaining a maximum recovery of 94%.

ANALYSIS OF HEAVY METALS IN EFFLUENT AND SOIL FROM RANIPET DISTRICT, INDIA

The present study was focussed about the analysis of selected heavy metal in the five sampling stations from the Ranipet district. Effluent and soil (surface:<30cm and deep: >30cm) samples are collected from all the stations (TCC limited, Emerald Nagar, Puliyanganu lake, Puliyanganu and Karai SRP nagar). By acid digestion method, the heavy metal composition of the samples were analysed. Among the five stations, effluent chromium levels found high in Puliyanganu (S4) whereas high incidence of surface and deep soil Cr levels observed as 990.28±121.3 and 1685.47±221.6mg/Kg respectively.Our results evidenced that the heavy metal levels in the tested sampling stations were above the permissible limits.

Chromium (VI) removal using cerium doped iron oxide nanoparticles

The presence of high concentrations of hexavalent chromium in effluents is extremely harmful to the environment. To solve this environmental problem, several chemical treatments are applied in order to reduce the concentration of these ions in aqueous solutions, generally involving the reduction of Cr (VI) to Cr (III). Adsorption is a simple, efficient and economical method for the removal of contaminants, when a low-cost adsorbent is used. In this work, particles of cerium-doped iron oxides with different stoichiometric ratios were produced, with the adsorption capacity being evaluated by the removal of hexavalent chromium present in aqueous solution. Doping with cerium produced iron oxides with high surface area and certain textural characteristics, which favored the ability to remove chromium from aqueous solutions with a mechanism that combines adsorption and photoreduction of Cr (VI).

Greener Approach for Leather Tanning Using Less Chrome with Plant Tannins and Tannins Mediated Nanoparticles

Making out animal skins or hides to leather is commonly called as tanning. This research was done for utilizing tannins of some medicinal plants and tannin induced green-synthesized silver nanoparticles along with minimal concentration of chromium to enhance the physical and mechanical properties of leather and thereby reducing the pollution caused by chromium in effluent which crucially affect the soil fertility, ground and surface water. In this study, Cassia alata, Euphorbia hirta, Thespesia populnea and Wrightia tinctoria were collected and tannins were extracted from the leaves. Tannins were utilized for production of silver nanoparticles. The extracted tannins and tannin induced silver nanoparticles were characterized, where the silver nanoparticles were found to be crystalline. Further, the tannin and tannin induced silver nanoparticles were used in leather processing either alone or in combination with chromium. The quality of tannin/silver nanoparticle treated leather was compared with chemically tanned leather for its tensile strength, tear strength, shrinking temperature, etc.

Hexavalent chromium removal from municipal wastewater using ferrous salts

Abstract Hexavalent chromium is difficult to remove during conventional biological wastewater treatment. This is because the hexavalent form is dissolved and is only sparingly removed by adsorption onto biomass in conventional processes. Hexavalent chromium is of particular concern because of its aquatic toxicity, and an increasing number of wastewater works have effluent discharge limits to protect receiving water courses, some as low as 8 μg Cr L−1. A relatively simple improvement to the removal of chromium could be made by switching the aluminium or ferric solution dosed at most treatment works for the removal of solids, organic load and phosphorus, to a ferrous salt. Ferrous reduces hexavalent chromium to insoluble trivalent chromium, which can be readily settled out of waste streams as a particulate. In the present study, laboratory experiments using real wastewater and ferrous doses of 10 mg Fe L−1 achieve the chromium discharge consent of 8 μg L−1 from initial solution concentrations of up to 40 μg L−1. A ferrous chloride dosing system was subsequently installed at an operational sewage treatment works that has produced an average final effluent chromium concentration of 2.4 μg L−1 (with a maximum of 4.2 μg L−1), despite influent spikes >300 μg L−1.

Phytoextraction of chromium from electroplating effluent by Tagetes erecta (L.)

Abstract Industrialization has made developing countries ‘hot-spots’ of metal pollution. Being non-biodegradable, they persist in the environment and result in bioaugmentation. To remediate this persistent pollutant, the green technology, phytoremediation has been attempted in the present study. Analysis of variance showed the probability (P) of significant chromium (Cr) uptake by shoot (P ≤ 0.03) and highly significant Cr accumulation in root (P ≤ 0.0001). Cr-induced physiological changes were observed in the form of significant decrease in chlorophyll content (P ≤ 0.004) and significant increase in biomass (P ≤ 0.002), from day 7 to day 35 when exposed to 2, 4 and 6 mg kg−1 of chrome effluent. Tagetes erecta in association with rhizobacteria (Bacillus cereus-CK 505 and Enterobacter cloacae-CK 555) was found to accumulate high levels (94%) of Cr within a short period of 35 days.

Akumulasi dan Toksisitas Effluen yang Mengandung Kromium pada Ikan Gupi (Poecilia reticulata)

Accumulation and toxicityofchromium in leather-tannery effluent on guppies were investigated. An acute (96 hour) statictoxicitytestingusing 5 serialdilution of theeffluentwas conducted. Each serial dilution consisted of 3 replicates, with eachreplicate contained 5litres of diluted effluent and 10 fish. Theeffluent was diluted 0.2%to 3.2%(v/v).Theconcentrations of chromium in thedilutedeffluent and fishrange from 0.9 - 9.1 µg.mL-1and 1.4 - 58.9 µg.g-1w.w, respectively. Bioconcentration factors inthisstudy vary from 1 to 39, with a median value of 6.2. The values of LC50and ILC50are 4.2 µg.mL-1and 56 µg.g-1w.w, respectively. The results show that chromiumaccumulates in guppy and causesacute toxicity. A comparison withthe concentrations of chromium in effluent, water, and fish from otherstudies was also reported.

A novel chrome tanning process for minimization of total dissolved solids and chromium in effluents

Presence of chlorides and chromium in the tannery effluents are serious environmental concerns of leather making. Elimination or minimization of these is active area of global leather research. Treatment system for removal of chlorides from effluents is very expensive and affects seriously the viability of the tanning industry. Long lasting and convincing solution to the problem rests on development of a common salt free tanning system with high chromium exhaustion levels. Common salt, also known as sodium chloride, is most responsible for the salinity in tannery effluents. In this context a new common salt free tanning process has been developed to overcome the stated problems of industrial leather making. The new process affords use of less chromium tanning agents apart from completely eliminating use of common salt in tanning. The reduction in specific consumption of chromium (ton of equivalent chromium per ton of pelts treated) for tanning in the prescribed method provides significant economic benefits to the new process. Substantial reduction of Total Dissolved Solids (TDS) reduction in effluents has been achieved by adopting the new process. The process essentially is based on modification of the reactants activity to ensure high uptake of tanning material. The process also affords uniform distribution of chromium in the leather. The chemical, physical and microscopical analyses indicate comparable leather properties processed by new method when assessed along with conventionally processed leathers. The innovation which has been commercially implemented provides an economical and simple solution to a century old problem.

Microbial Waste Biomass for Removal of Chromium(VI) from Chrome Effluent

ABSTRACT Microbial waste biomass, a by-product of the fermentation industry, was developed as a biosorbent to remove hexavalent chromium (Cr) from the acidic effluent of a metal processing industry. In batch sorption, 100% Cr(VI) removal was achieved from aqueous solution in 30 min contact at pH 4.0–5.0. The Cr(VI) sorption equilibrium was evaluated using the Langmuir and Freundlich models, indicating the involvement of ion exchange and physicochemical interaction. Fourier transform infrared (FTIR) analysis revealed the presence of amine, hydroxyl, and imine functional groups present on the surface of microbial biomass that are involved in Cr binding. In a continuous sorption system, 95 mg L−1 of Cr(VI) was adsorbed before the column reached a breakthrough point of 0.1 mg L−1 Cr(VI) at the column outlet. An overall biosorption capacity of 12.6 mg Cr(VI) g−1 of dry microbial waste was achieved, including the partially saturated portion of the dynamic sorption zone. Insignificant change in metal removal was observed up to 10 cycles. In pilot-scale studies, 100% removal of Cr(VI) was observed up to 5 weeks, and the method was found to be cost-effective, commercially viable, and environmentally friendly, as it does not generate toxic chrome sludge.

Estimation of Chromium in Effluents from Tanneries of Korangi Industrial Area

Estimation of Chromium in Effluents from Tanneries of Korangi Industrial Area

Activity levels of phosphatases of the air-breathing catfish Mystus cavasius exposed to electroplating industrial effluent chromium

In India chromium is widely used in all electroplating industries. Chromium in electroplating industrial effluent has been shown to inhibit many enzymes at different segments of metabolism. Chromium especially inhibits pyruvate oxidases system and phosphatases. The present study was undertaken to evaluate the effect of effluent chromium on phosphatases on exposure to sub-lethal concentration (0.25%) for a period of 24, 48, and 72 h and 15 d. Activity levels of acid phosphatase and alkaline phosphatase decreased significantly in the gill and air bladder tissues of experimental catfish, Mystus cavasius, when compared with that of controls.

Studies on Chromate Removal by Chromium-Resistant Bacillus sp. Isolated from Tannery Effluent

A chromate-removing strain was isolated from spent chrome effluent and identified as Bacillus circulans strain MN1. The isolated strain was studied for resistance to Cr (VI) and its ability to remove Cr (VI). The strain was found to tolerate Cr (VI) concentration as high as 4500 mg/L, but the cells growth was heavily influenced when initial Cr (VI) concentration was increased between 1110 mg/L and 4500 mg/L while Cr(VI) at 500 mg/L to 1110 mg/L did not suppressed the cells growth. The experiments also demonstrated that the cells removed toxic Cr (VI) more efficiently at 30?C compared with that at 25?C and 35?C. The optimum initial pH for Cr (VI) removal was 5.6 and final pH values of 5.1-5.6 were observed for initial pH 5.2-5.7.

Detoxification and accumulation of chromium from tannery effluent and spent chrome effluent by Paecilomyces lilacinus fungi

The tannery industry process involves chromium (Cr) salts as a main constituent of the process. The Cr recovery is a part of the process where other salts are used to achieve separation and recovery for using Cr back in the process. The process steps may contain both forms of Cr [Cr(VI): hexavalent and Cr(III): trivalent]. The recovery of Cr from tannery industry effluent through biological systems is much needed. The diverse physicochemical characteristics of these effluents may limit the growth of microorganisms and hence the limitation towards possible practical application of microorganisms in real industrial effluent conditions. The present study attempted the ability of the Cr-resistant fungus Paecilomyces lilacinus [isolated through an enrichment culture technique at 25 000 mg l−1 of Cr(III)] to grow and remove Cr [Cr(VI) and Cr(III)] from two physicochemically different undiluted tannery industry effluents (tannery effluent and spent chrome effluent) in the presence of cane sugar as a carbon source. Such attempts are made keeping in view the potential integration of biological processes in the overall Cr removal and recovery processes to improve its efficiency and environmental sustainability. The fungus has broad pH tolerance range and can reduce Cr(VI) both in acidic (pH 5.5) and alkaline (pH 8.0) conditions. The fungus showed the ability to remove Cr(VI) (1.24 mg l−1) and total Cr (7.91 mg l−1) from tannery effluent below the detection level within 18 h and 36 h of incubation, respectively, and ability to accumulate 189.13 mg Cr g−1 of dry biomass within 600 h of incubation from spent chrome effluent [containing 3731.4 mg l−1 of initial Cr(III) concentration].At 200 mg l−1 of Cr(VI) in growth media, with 100% detoxification and with only 10.54% of total Cr accumulation in the biomass, P. lilacinus showed Cr(VI) reduction as a major mechanism of Cr(VI) detoxification. The time-course study revealed the log phase of the growth for the maximum specific reduction of Cr(VI) and stationary phase of the growth for its maximum specific accumulation of both the forms of Cr [Cr(III) and Cr(VI)] in its biomass. In growth media at 50 mg l−1 and 200 mg l−1 of Cr(VI), P. lilacinus showed 100% reduction within 36 h and 120 h of incubation, respectively. The high degree of positive correlation and statistically high degree of relationship (r2 = 0.941) between the fungal growth and % Cr(VI) reduction by the fungus support the role of metabolically active cellular growth in Cr(VI) reduction by the fungus. Results indicate that expanded solid (sludge) retention times (SRTs) (stationary phase) can be recommended for the removal of Cr(III) through accumulation. In case of Cr(VI), reduction needs a priority; therefore, a non-expanded SRT is recommended for designing a continuous-flow completely stirred bioreactor so that a log phase of cellular growth can be maintained during the reduction process. This study reveals the strong potential of P. lilacinus fungi for the removal of Cr from tannery effluent and spent chrome effluent.

Removal of Cr(VI) from aqueous solution by fungal biomass

AbstractChromium compounds are released by industrial processes including leather production, mining, petroleum refining, in textile industry and dyeing. They are a significant threat to the environment and public health because of their toxicity. Removal of hexavalent chromium by living biomass of different fungi was effective in the order of Aspergillus terricola>Aspergillus niger>Acremonium strictum>Aureobasidium pullulans>Paecilomyces variotii>Aspergillus foetidus>Cladosporium resinae>Phanerochaete chrysosporium. Non‐living dried fungal biomass showed higher potential for metal removal than living cells. Among all fungi dead biomass of P. chrysosporium, C. resinae and P. variotii had the maximum specific chromium uptake capacity, which was 11.02, 10.69 and 10.35 mg/g of dry biomass respectively at pH 4.0–5.0 in batch sorption. Removal of Cr(VI) by P. chrysosporium from multi‐metallic synthetic solution as well as chrome effluent was significant by bringing down the residual concentration to 0.1 mg/L in the effluent, which falls within the permissible range and its removal was not affected by the presence of other metal ions such as Fe, Zn and Ni. Fourier transform infrared spectral analysis revealed the presence of carboxylate (C=O) and amine (−NH, −NH) functional groups commonly present on the cell surface of all fungi, with possible involvement in chromium binding. The result indicates that non‐living fungal biomass either obtained as a by‐product of fermentation industry or mass produced using inexpensive culture media can be used for bioremediation of Cr(VI) from chrome effluent on large scale.

Bioremediation of chromium in tannery effluent by microbial consortia

Chromium is the most toxic and common among the heavy metal pollutants of industrial effluents. In the present work the chromium remediation ability of Bacillus subtilis, Pseudomonas aeruginosa and Saccharomyces cerevisiae in consortia and in their immobilized forms was studied and their efficiencies were compared. Flame Atomic Absorption Spectroscopy and diphenyl carbazide method was used to quantify chromium in the effluent. The chromium content of the effluent was around 770 mg/l before remediation, after which it reduced to 5.2 – 5.7 mg/l. The best activity was observed by S. cerevisiae - P. aeruginosa consortia, followed by immobilized beads of S. cerevisiae and S. cerevisiae - B. subtilis consortia.

Efficiency assessment of Common Effluent Treatment Plant (CETP) treating tannery effluents

The efficacy of Common Effluent Treatment Plant (CETP) based on activated sludge process employed for treatment of tannery effluent was analyzed for the efficiency to reduce chromium and other contaminants. Physico-chemical parameters of treated effluent were found within permissible levels of statutory limits. A significant reduction in COD and BOD levels were achieved during the course of treatment in CETP. A reduction of 98.46%, 87.5%, and 96.15% in bacterial counts especially in pathogens like Escherichia coli, Vibrio spp., and Pseudomonas spp. were observed after treatment. Pathogens were not detected in the dried sludge. Complete elimination of fecal streptococci was observed in treated effluent. Around 10.8% of microbial isolates from the effluent showed ability to reduce chromate >90%. In treated effluent chromium level was 5.48 mg/L, which exceeds the statutory limit of Indian standards. Cleaner production options to reduce chromium levels before discharging into water bodies is discussed.

Studies of chromium removal from tannery wastewaters by algae biosorbents, Spirogyra condensata and Rhizoclonium hieroglyphicum

Chromium in the effluent is a major concern for tanning industry. Chemical precipitation methods are commonly employed for the removal of chromium but this leads to formation of chrome-bearing solid waste, plus it is uneconomical when the concentration of chromium in the effluent is low. Ion exchange and membrane separation methods are relatively expensive. In this study, two algae namely, Spirogyra condensata and Rhizoclonium hieroglyphicum have been employed to remove chromium from tannery effluent. The effect of pH and chromium concentration showed S. condensata to exhibit maximum uptake of about 14 mg Cr(III)/g of algae at optimum pH of 5.0 whereas R. hieroglyphicum had 11.81 mg of Cr(III)/g of algae at pH of 4.0. Langmuir and Freundlich models were applied. Increase of initial concentration of Cr resulted to a decrease in adsorption efficiency. Dilute sulphuric acid (0.1 M) showed good desorption efficiency (>75%). Interference from cations negatively impacted on biosorption of chromium. Immobilized algae on Amberlite XAD-8 in a glass column, gave better recovery of chromium in tannery effluent compared to a batch method with unimmobilized algae. Fourier transform infra red (FT-IR) analysis of the two algae revealed the presence of carboxyl groups as possible binding sites.

Thermodynamic and breakthrough column studies for the selective sorption of chromium from industrial effluent on activated eucalyptus bark

Studies were carried out on adsorption of Cr(VI) on an adsorbent made from eucalyptus bark. Results revealed that sorption of chromium on activated eucalyptus bark (AEB) was endothermic in nature. Thermodynamic parameters such as the entropy change, enthalpy change and Gibb’s free energy change were found out to be 100.97 J mol −1 K −1, 33 kJ mol −1 and −0.737 kJ mol −1, respectively. Industrial chrome effluent of different chromium concentration at different pH was used as feedstock for the fixed bed adsorption studies. When effluent was fed to the column at low pH of 2, the breakthrough volume increased significantly compared to effluent at higher pH of 4.85. The surface properties of sorbent were characterized by the Scanning electron microscopy, X-ray diffraction technique and Infrared techniques. It was concluded that AEB sorbent column could be used effectively for removal of chromium from industrial effluents by reducing the pH of chrome effluent to two and at optimal column conditions.