Present study deals with the isolation and characterization of a bacterium capable for the effective reduction of Cr(VI) from tannery wastewater. Based on the 16S rRNA gene sequence analysis, this ...bacterium was identified as Cellulosimicrobium sp. (KX710177). During the Cr(VI) reduction experiment performed at 50, 100, 200,and 300mg/L of Cr(VI) concentrations, the bacterium showed 99.33% and 96.98% reduction at 50 and 100mg/L at 24 and 96h, respectively. However, at 200 and 300mg/L concentration of Cr(VI), only 84.62% and 62.28% reduction was achieved after 96h, respectively. The SEM analysis revealed that bacterial cells exposed to Cr(VI) showed increased cell size in comparison to unexposed cells, which might be due to either the precipitation or adsorption of reduced Cr(III) on bacterial cells. Further, the Energy Dispersive X-ray (EDX) analysis showed some chromium peaks for cells exposed to Cr(VI), which might be either due to the presence of precipitated reduced Cr(III) on cells or complexation of Cr(III) with cell surface molecules. The bacterium also showed resistance and sensitivity against the tested antibiotics with a wide range of MIC values ranging from 250 to 800mg/L for different heavy metals. Thus, this multi-drug and multi-metal resistant bacterium can be used as a potential agent for the effective bioremediation of metal contaminated sites.
•Characterization of Cr(VI) reducing bacterium from tannery wastewater.•16S rRNA gene sequence analysis identified bacterium as Cellulosimicrobium sp.•SEM, EDX & FTIR analysis.•MIC values ranging from 250 to 800mg/L for different heavy metals.
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•Polyhydroxyalkanoates a potential biopolymer substitute for conventional plastics.•Critically reviewed various waste streams for sustainable and inexpensive PHA production.•Recent ...advances on fermentation strategies & synthetic biology for higher PHA production.•Discussed PHA- nanocomposites and their application in various sectors.•Future perspectives & technical challenges for efficient waste-bioplastic production addressed.
Polyhydroxyalkanoates (PHA) are appealing as an important alternative to replace synthetic plastics owing to its comparable physicochemical properties to that of synthetic plastics, and biodegradable and biocompatible nature. This review gives an inclusive overview of the current research activities dealing with PHA production by utilizing different waste fluxes generated from food, milk and sugar processing industries. Valorization of these waste fluxes makes the process cost effective and practically applicable. Recent advances in the approaches adopted for waste treatment, fermentation strategies, and genetic engineering can give insights to the researchers for future direction of waste to bioplastics production. Lastly, synthesis and application of PHA-nanocomposites, research and development challenges, future perspectives for sustainable and cost-effective PHB production are also discussed. In addition, the review addresses the useful information about the opportunities and confines associated with the sustainable PHA production using different waste streams and their evaluation for commercial implementation within a biorefinery.
Crystal Violet (CV), a triphenylmethane dye, has been extensively used in human and veterinary medicine as a biological stain, as a textile dye in textile processing industries and also used to ...provide a deep violet color to paints and printing ink. CV is also used as a mutagenic and bacteriostatic agent in medical solutions and antimicrobial agent to prevent the fungal growth in poultry feed. Inspite of its many uses, CV has been reported as a recalcitrant dye molecule that persists in environment for a long period and pose toxic effects in environment. It acts as a mitotic poison, potent carcinogen and a potent clastogene promoting tumor growth in some species of fish. Thus, CV is regarded as a biohazard substance. Although, there are several physico-chemical methods such as adsorption, coagulation and ion-pair extraction reported for the removal of CV, but these methods are insufficient for the complete removal of CV from industrial wastewaters and also produce large quantity of sludge containing secondary pollutants. However, biological methods are regarded as cost-effective and eco-friendly for the treatment of industrial wastewaters, but these methods also have certain limitations. Therefore, there is an urgent need to develop such eco-friendly and cost-effective biological treatment methods, which can effectively remove the dye from industrial wastewaters for the safety of environment, as well as human and animal health.
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•Rapid Remazol Brilliant Blue R dye decolourisation achieved by laccase without redox mediator.•Optimization by Box–Behnken designenhanced dye decolourisation (97.18%).•Dye ...degradation has been affirmed by UV–visible spectroscopy and FTIR analysis.•Laccase treated dye found relatively less phyto- and cytotoxic.•Molecular docking analysis revealed the significant binding affinity between RBBR-laccase.
Biodegradation of environmentally hazardous synthetic dyes by enzymes has been achieved the highest interest in recent years. In this work, we optimized Remazol Brilliant Blue R (RBBR) dye biodegradation by Arthrographis kalrae derived laccase via the Box-Behnken design (BBD) approach of the surface response methodology (RSM). Optimization of dye decolourisation by one variable at a time (OVAT) approach resulted in optimal dye decolourisation at laccase dose (2 IU mL−1), pH (7.0), temperature (35 °C), incubation time (240 min), and initial dye concentration (100 mg L-1). The optimized process through BBD enhanced dye decolourisation (97.18%). Fourier Transform Infrared Spectroscopy and UV–Visible Spectrophotometry have proven biodegradation. In addition, in comparison to untreated samples, the laccase-treated dye sample showed relatively less phyto- and cytotoxic effect on Allium cepa L. Extra Precision Glide docking exhibited the binding affinity score of −5.355 kcal mol−1, between laccase-RBBR complex.
Textile industry wastewater (TIWW) is considered as one of the worst polluters of our precious water and soil ecologies. It causes carcinogenic, mutagenic, genotoxic, cytotoxic and allergenic threats ...to living organisms. TIWW contains a variety of persistent coloring pollutants (dyes), formaldehyde, phthalates, phenols, surfactants, perfluorooctanoic acid (PFOA), pentachlorophenol and different heavy metals like lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr), zinc (Zn) and nickel (Ni) etc. TIWW is characterized by high dye content, high pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), total suspended solids (TSS), total organic carbon (TOC), chlorides and sulphates. Thus, requires adequate treatment before its final discharge into the water bodies to protect public health and environment. The treatment of TIWW is a major challenge as there is no particular economically feasible treatment method capable to adequately treat TIWW. Therefore, there is a need to develop a novel, cost-effective and eco-friendly technology for the effective treatment of TIWW. This review paper emphasizes on the different textile industry processes, wastewater generation, its nature and chemical composition, environmental impacts and health hazards and treatment approaches available for TIWW treatment. It also presents various analytical techniques used to detect and characterize TIWW pollutants and their metabolites, challenges, key issues and future prospectives.
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•Textile wastewater has unfixed dyes, salts, phthalates, phenols and toxic metals.•Textile wastewater pollutants have environmental and health hazards.•Textile wastewater pollutants have carcinogenic, mutagenic and cytotoxic effects.•Various existing and advanced treatment methods are discussed.•Various analytical techniques used to characterize pollutants are discussed.
Melanoidins are natural condensation products of sugar and amino acids produced by non-enzymatic Maillard amino–carbonyl reaction taking place between the amino and carbonyl groups in organic ...substances. Melanoidins extensively exist in food products, drinks and wastewaters released from distilleries and fermentation industries. Melanoidins are very important from the nutritional, physiological and environmental aspects and due to their structural complexity, dark colour and offensive odor, these pose serious threat to soil and aquatic ecosystem that release of melanoidins cause increased load of recalcitrant organic material to natural water bodies. This then causes the problems, like reduction of sunlight penetration, decreased photosynthetic activity and dissolved oxygen concentration whereas on land, it causes reduction in soil alkalinity and inhibition of seed germination. Further, due to the possibility of complexation reactions of introduced melanoidins with metal ions, they could influence the biogeochemical cycle of many constituents in natural waters. This review presents an overview to dramatic progress to understand the synthesis, chemical structure and degradation pathway of melanoidins as well as microbial strategies for the degradation and decolourisation of melanoidins.
The leather industry is a major source of environmental pollution in India. The wastewater generated by leather industries contains very high pollution parameters due to the presence of a complex ...mixture of organic and inorganic pollutants even after the treatment at a Common Effluent Treatment Plant (CETP) and disturbs the ecological flora and fauna. The nature, characteristics and toxicity of CETP treated wastewater is yet to be fully elucidated. Thus, this study aims to characterize and evaluate the toxicity of CETP treated tannery wastewater collected from the Unnao district of Uttar Pradesh, India. In addition to measuring the physico-chemical parameters, the residual organic pollutants was identified by GC-MS analysis and phytotoxicity, cytotoxicity and genotoxicity of the treated wastewater was evaluated using Vigna radiata L. and Allium cepa L. Results showed that the treated wastewater contained very high pollution parameters (TDS 3850 mg/L, BOD 680 mg/L, COD-1300 mg/L). GC-MS analysis revealed the presence of various types of residual organic pollutants including benzoic acid, 3-4,-(T-butyl) Phenyl furan-2-5-dione, benzeneacetamide, resorcinol, dibutyl phthalate, and benzene-1,2,4-triol. Further, toxicological studies showed the phytotoxic nature of the wastewater as it inhibited seed germination in V. radiata L. and root growth of A. cepa. Genotoxicity was evidenced in the root tip cell of A. cepa where chromosomal aberrations (stickiness, chromosome loss, C-mitosis, and vagrant chromosome) and nuclear abnormalities like micronucleated and binucleated cells were observed. Thus, results suggested that it is not safe to discharge these wastewater into the environment.
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•Tannery wastewater rich in organic and inorganic pollutants.•Tannery wastewater possesses genotoxic and cytotoxic pollutants.•Phytotoxic nature of tannery wastewater was evaluated by Vigna radiata seeds.•Allium cepa chromosomal tests revealed genotoxic nature of treated tannery wastewater.•Wastewater also induced chromosomal aberrations and nuclear abnormalities in cells.
Tannery wastewater (TWW) is of serious environmental concern to pollution control authorities, because it contains highly toxic, recalcitrant organic and inorganic pollutants. The nature and ...characteristics of recalcitrant organic pollutants (ROPs) are not fully explored to date. Hence, the purpose of this study was to characterize and identify the ROPs present in the treated TWW. Gas chromatography–mass spectrometry data analysis showed the presence of a variety of ROPs in the treated TWW. Results unfolded that benzyl chloride, butyl octyl phthalate, 2,6-dihydroxybenzoic acid 3TMS, dibutyl phthalate, benzyl alcohol, benzyl butyl phthalate, 4-chloro-3-methyl phenol, phthalic acid, 2′6′-dihydroxyacetophenone, diisobutyl phthalate, 4-biphenyltrimethylsiloxane, di-(-2ethy hexyl)phthalate, 1,2-benzenedicarboxylic acid, dibenzyl phthalate, and nonylphenol were present in the treated TWW. Due to endocrine disrupting nature and aquatic toxicity, the U.S. Environmental Protection Agency classified many of these as “priority pollutants” and restricted their use in leather industries. In addition, the physicochemical analysis of the treated TWW also showed very high BOD, COD, and TDS values along with high Cr and Pb content beyond the permissible limits for industrial discharge. Furthermore, phytotoxicity assessment unfolds the inhibitory effects of TWW on the seed germination, seedling growth parameters, and
α
-amylase activity in
Phaseolus aureus
L. This indicates that the TWW discharged even after secondary treatment into the environment has very high pollution parameters and may cause a variety of serious health threats in living beings upon exposure. Overall, the results reported in this study will be helpful for the proper treatment and management of TWW to combat the environmental threats.
Enzyme-based catalysis has become one of the most important disciplines in organic synthesis and plays a noteworthy role in the establishment of many chemical industries, e.g. fine chemicals, food or ...energy, textiles, agricultural, cosmeceutical, medicinal and pharmaceutical industries. However, pristine enzymes fail to demonstrate requisite functionalities for an industrial setting where extremely specific and stable catalysts are required. Immobilization enhances the catalytic stability and activity of enzymes and trims the overall cost burden of the enzyme. Therefore, it widely endeavours for proficient, sustainable, and environmentally responsive catalytic processes. Amongst several immobilization strategies, e.g. (1) supports-assisted, i.e. physical or covalent coupling and (2) supports-free techniques, i.e. cross-linked enzyme crystals (CLECs) or aggregates are the most promising ones and widely pursued for enzyme immobilization purposes. This perspective review focuses on up-to-date developments in the area of enzyme immobilization and presents their potentialities to upgrade and/or modify enzyme properties. Both types of immobilization strategies, i.e. supports-assisted and supports-free techniques are discussed with particular reference to CLECs or aggregates and protein-coated microcrystals. Also, several useful traits achieved after immobilization are also discussed in the second half of the review.
Distillery industries are the key contributor to the world's economy, but these are also one of the major sources of environmental pollution due to the discharge of a huge volume of dark colored ...wastewater. This dark colored wastewater contains very high biological oxygen demand, chemical oxygen demand, total solids, sulfate, phosphate, phenolics and various toxic metals. Distillery wastewater also contains a mixture of organic and inorganic pollutants such as melanoidins, di-n-octyl phthalate, di-butyl phthalate, benzenepropanoic acid and 2-hydroxysocaproic acid and toxic metals, which are well reported as genotoxic, carcinogenic, mutagenic and endocrine disrupting in nature. In aquatic resources, it causes serious environmental problems by reducing the penetration power of sunlight, photosynthetic activities and dissolved oxygen content. On other hand, in agricultural land, it causes inhibition of seed germination and depletion of vegetation by reducing the soil alkalinity and manganese availability, if discharged without adequate treatment. Thus, this review article provides a comprehensive knowledge on the distillery wastewater pollutants, various techniques used for their analysis as well as its toxicological effects on environments, human and animal health. In addition, various physico-chemicals, biological as well as emerging treatment methods have been also discussed for the protection of environment, human and animal health.
•Endocrine disrupting chemicals of distillery wastewater.•Environmental and health hazards of distillery wastewater pollutants.•Analytical techniques used for distillery wastewater pollutants analysis.•Physico-chemical, biological and emerging treatment methods of distillery wastewater.•Merits and demerits of various distillery wastewater treatment approaches.
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