Kinetic study for removal of cationic hexamethyl pararosaniline chloride dye using phytoremediation

The present investigation provides a kinetic study for the removal of hexamethyl pararosaniline chloride, a hazardous dye, by phytoremediation using a water plant. It reveals Salvinia molesta has a phytoremediation tendency. The ability of Salvinia molesta to remove crystal violet (CV) dye is investigated with kinetic study in this research. Phytoremediation is done for different concentrations of hexamethyl pararosaniline chloride with varying pH and weight of Salvinia molesta Mitchell. About 88% of hexamethyl pararosaniline chloride has been decolourised from 50 mg L-1 solution at pH of 6 with 4 g of Salvinia molesta Mitchell. The results obtained for hexamethyl pararosaniline chloride removal at pH of 6 are studied for pseudo-first order, pseudo-second order and Elovich kinetics. The resulting curve for removal of hexamethyl pararosaniline chloride indicates that phytoremediation process follows pseudo-second order kinetics with correlation value R2 ≥ 0.985. The Salvinia molesta used at pH 6 has been reused and the decolourisation has been achieved at about 84% for 50 mg L-1 solution of CV dye. The FTIR results reveal the phytoextraction of CV in the roots by interaction of functional groups. From the experimental results, Salvinia molesta Mitchell can be used to treat textile wastewater and wet land.

In situ treatment of real textile effluent in constructed furrows using consortium of Canna indica and Saccharomyces cerevisiae and subsequent biochemical and toxicity evaluation

Emerging contaminants removals like dyes and heavy metals from the textile effluent have an immense challenge. The present study focuses on the biotransformation and detoxification of dyes and in situ textile effluent treatment by plants and microbes efficiently. A mixed consortium of perennial herbaceous plant Canna indica and fungi Saccharomyces cerevisiae showed decolorization of di-azo dye Congo red (CR, 100 mg/L) up to 97% within 72 h. Root tissues and Saccharomyces cerevisiae cells revealed induction of various dye-degrading oxidoreductase enzymes such as lignin peroxidase, laccase, veratryl alcohol oxidase and azo reductase during CR decolorization. Chlorophyll a, Chlorophyll b and carotenoid pigments were notably elevated in the leaves of a plant during the treatment. Phytotransformation of CR into its metabolic constituents was detected by using several analytical techniques, including FTIR, HPLC, and GC-MS and its non-toxic nature was confirmed by cyto-toxicological evaluation on Allium cepa and on freshwater bivalves. Mix consortium of plant Canna indica and fungi Saccharomyces cerevisiae efficiently treated textile wastewater (500 L) and reduced ADMI, COD, BOD, TSS and TDS (74, 68, 68, 78, and 66%) within 96 h. In situ textile wastewater treatment for in furrows constructed and planted with Canna indica, Saccharomyces cerevisiae and consortium-CS within 4 days reveals reduced ADMI, COD, BOD, TDS and TSS (74, 73, 75, 78, and 77%). Comprehensive observations recommend this is an intelligent tactic to exploit this consortium in the furrows for textile wastewater treatment.

Degradation of Diazo Dye and its Kinetic and Equilibrium Studies Using the Potential of Bryophyllum fedtschenkoiin Aqueous System

Phytoremediation is emerging as an eco-friendly, innovative, and cost-effective approach for the removal of textile dyes from wastewater from the previous decade. The current research work aims to explore the potential of a terrestrial ornamental plant, Bryophyllum fedtschenkoi (Raym.-Hamet & H. Perrier) Lauz.-March. for remediating the diazo dye as Congo red (CR) in aqueous form. B. fedtschenkoi was grown hydroponically before treatment with 100 mL of a different concentration of CR dye solution. A maximum decolorization potential of 90% was obtained for 10 mg L^- 1 after 40 h of equilibrium. The kinetic studies have revealed that the experimental results for the removal of CR dye using the B .fedtschenkoi plant are suitable for Pseudo-first order with R² ≥ 0.92, while the equilibrium studies agreed with the Freundlich adsorption isotherm with R² ≥ 0.909. The dye removal by the plant was confirmed with the help of analytical techniques Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Gas Chromatography-Mass Spectrometry (GC-MS) and High-Performance Liquid Chromatography (HPLC) were also performed on dye-degraded metabolites to explore the mechanism of dye degradation.

Application of Salvinia sps. in remediation of reactive mixed azo dyes and Cr (VI) - Its pathway elucidation

The emerging industrialization has resulted in the rapid growth of textile industries across the globe. The presence of xenobiotic pollutants in textile wastewater threatens the ecosystem. Applying different microbes (bacteria, fungi & algae) has paved the way for phytoremediation - the eco-friendly, cost-effective method. The present study focuses on the phytoremediation of reactive dyes - Reactive red, Reactive Brown & Reactive Black and Cr (VI) in synthetic textile wastewater using Salvinia sps. The mixed azo dyes of each 100 mg/L showed decolourization of 75 ± 0.5% and 82 ± 0.5% of removal of 20 mg/L of Cr (VI) after eight days of incubation in a phytoreactor setup. Chlorophyll analysis revealed the gradual decrease in the photosynthetic pigments during the remediation. The degraded metabolites were analyzed using FT-IR and showed the presence of aromatic amines on day zero, which were converted to aliphatic amines on day four. The GC-MS analysis revealed the disruption of -NN- bond, rupture of -CN- bond, scission of -N-N-bond, and loss of -SO₃H from the Reactive Black dye leading to the formation of an intermediate p-Hydroxy phenylhydrazinyl. The rupture of Reactive red dye resulted in the formation of p-Hydrazinyl toluene sulphonic acid, Naphthyl amine -3,6-disulphonic acid and 8-Hydroxy Naphthyl amine -3,6-disulphonic acid. Decarboxylation, desulphonation, deoxygenation and deamination of Reactive Brown dye showed the presence of different metabolites and metabolic pathways were proposed for the reactive azo dyes which were phytoremediated.

Decolorization of safranin using Fissidens species and its ecotoxicological assessments: An in vitro and in silico approach

Decolorization of safranin was investigated using Fissidens species in a batch system under optimized conditions. The decolorization efficiency was improved by optimizing the conditions such as initial pH (3-9), temperature (25-45 °C), initial dye concentration (10-50 mg/L), biosorbent dosage (100-500 mg/L) and contact time (1-6 days). Maximum decolorization (95%) was recorded at initial pH of 6 with dye concentration of 20 mg/L, biosorbent dosage of 200 mg/L at 30 °C and contact time of 2 days. Desorption studies revealed 0.1 N NaOH as the best desorbing agent with 92% recovery on third day. Experimental data well fitted to Langmuir isotherm and Pseudo-second order kinetic model. The negative values of ΔG^o and positive value of ΔS^o and ΔH^o indicates that the reaction is spontaneous, favorable and endothermic. The biosorbent - dye interactions were confirmed using UV-Vis, FT-IR, XRD and FE-SEM with EDX studies. The detoxified nature of the dye degraded metabolites was confirmed by the significant growth of green gram. The color fastness and color strength of the fabrics dyed using Fissidens species treated dye solution were compared with the tap water dyed fabrics which indicated the reuse potential of treated water in textile sector. The decolorization efficiency was further confirmed through in silico approach, where safranin well docked with the active sites of Photosystem II protein D1 of the Fissidens species. Thus, the present study proves that Fissidens species is a promising biosorbent for safranin decolorization and will lay a platform for the control and management of environmental pollution.

Microbial bioremediation strategies with wastewater treatment potentialities - A review

The demand for innovative waste treatment techniques has arisen because of the establishment and operation of rigorous waste discharge guidelines into the environment. Due to the rapid increase in the human population, wastewater treatment is a procedure of increasing significance. As a result, wastewater treatment systems are intended to sustain high activities and densities of such microorganisms which meet the different purification requirements. The waste produced by the pharmaceutical industry, if not adequately treated, has harmful repercussions for the environment as well as public health. Bioremediation is an innovative and optimistic technology that can be used to remove and reduce heavy metals from polluted water and contaminated soil. Because of cost-effectiveness and environmental compatibility, bioremediation using microorganisms has an excellent potential for future development. A diverse range of microorganisms, including algae, fungi, yeasts, and bacteria, can function as biologically active methylators, capable of modifying toxic species. Microorganisms play a crucial role in heavy metal bioremediation. Nanotechnology may minimize industry expenses by producing environmentally friendly nanomaterials to alleviate these contaminants. The use of microorganisms in nanoparticle synthesis gives green biotechnology a positive impetus to cost reduction and sustainable production as a developing nanotechnology sector.

Treatment of the Allura Red food colorant contaminated water by a novel cyanobacterium Desertifilum tharense

The biosorption properties of a newly isolated and identified cyanobacterium called Desertifilum tharense were investigated in the current study. Following morphological and molecular identification (16S rRNA sequencing analysis), the food colorant removal potential of this new isolate was determined. Moreover, the isotherm, kinetic, and thermodynamic studies were performed, and also the biosorbent characterization was studied after and before colorant biosorption with Fourier transform infrared and scanning electron microscopy analysis. Additionally, the changes in chlorophyll content of the biosorbent were examined after and before colorant treatment. The newly isolated cyanobacterial biosorbent removed 97% of Allura Red food colorant/dye at 1,500 mg L^-1 initial dye concentration successfully at optimal conditions. Langmuir isotherm and pseudo-second-order kinetic models were fitted with the biosorption of the dye. The D-R model showed that the biosorption process occurred physically. The chlorophyll-a content of the biosorbent was negatively affected by the biosorption. The newly isolated and identified cyanobacterium seems to be a successful candidate for use to treat highly dye concentrated wastewaters.

A review on application of phytoremediation technique for eradication of synthetic dyes by using ornamental plants

Phytoremediation emerges as an innovative and eco-friendly technique to remediate textile dyes with the use of various categories of plants. In recent years, ornamental plants emerge as more attractive and effective substitute in comparison to edible plants for phytoremediation. Regardless of aesthetic value, some ornamental plants can be grown to remediate the sites contaminated with dyes, heavy metals, pesticides, or other organic compounds. In this review, we focus on pioneer research on synthetic dye removal using ornamental plants and evaluate the phytoremediation capability of ornamental plants for treatment of textile effluent. This paper also emphasized specific ornamental plants having high accumulation and tolerance ability for removal of dyes. The mechanisms explored for the phytoremediation of dyes by ornamental plants have also been explained. This review will also be helpful for researchers for exploring more new ornamental plants in phytoremediation technique.

Efficient Congo Red Removal Using Porous Cellulose/Gelatin/Sepiolite Gel Beads: Assembly, Characterization, and Adsorption Mechanism

Porous sustainable cellulose/gelatin/sepiolite gel beads were fabricated via an efficient 'hydrophilic assembly-floating droplet' two-step method to remove Congo red (CR) from wastewater. The beads comprised microcrystalline cellulose and gelatin, forming a dual network framework, and sepiolite, which acted as a functional component to reinforce the network. The as-prepared gel beads were characterized using FTIR, SEM, XRD, and TGA, with the results indicating a highly porous structure that was also thermally stable. A batch adsorption experiment for CR was performed and evaluated as a function of pH, sepiolite addition, contact time, temperature, and initial concentration. The kinetics and isotherm data obtained were in agreement with the pseudo-second-order kinetic model and the Langmuir isotherm, with a maximum monolayer capacity of 279.3 mg·g^-1 for CR at 303 K. Moreover, thermodynamic analysis demonstrated the spontaneous and endothermic nature of the dye uptake. Importantly, even when subjected to five regeneration cycles, the gel beads retained 87% of their original adsorption value, suggesting their suitability as an efficient and reusable material for dye wastewater treatments.

Phytoremediation of synthetic textile dyes: biosorption and enzymatic degradation involved in efficient dye decolorization by Eichhornia crassipes (Mart.) Solms and Pistia stratiotes L

The effectiveness of four aquatic floating plants: Eichhornia crassipes, Pistia stratiotes, Lemna minor, Salvinia sp., and a submerged plant Hydrilla sp. on decolorization and detoxification of five structurally different textile dyes: CI Direct Blue 201 (DB 201), Cibacron Blue FR, Cibanone Gold Yellow RK, Vat Green FFB, and Moxilon Blue GRL were studied. The E. crassipes and P. stratiotes showed complete decolorization of all the dyes tested, while Salvinia sp. (79-86%), L. minor (16-24%), and Hydrilla sp. (6-13%) were recorded as the least tolerance for all the dyes even after 14 days of incubation. Therefore, E. crassipes and P. stratiotes were selected for further studies using DB 201 as the model dye. E. crassipes and P. stratiotes showed complete decolorization of DB 201 at 48 and 84 h of incubation, respectively, and decolorization was well effective in the pH range 6-9. The crude extract of intracellular enzymes obtained from the roots of E. crassipes (46%) and P. stratiotes (20%) showed significant involvement on decolorization of DB 201, compared with the activity of crude extracellular extract and isolated endophytic bacteria and fungi (p ≤ 0.05). Further, 18 and 22% of biosorption of DB 201 dye were recorded by E. crassipes and P. stratiotes, respectively, suggesting that decolorization mechanisms of DB 201 dye by E. crassipes and P. stratiotes were based on biosorption and intracellular enzyme activities. The FTIR spectra and seed germination assay confirmed biodegradation and detoxification of DB 201 dye by E. crassipes and P. stratiotes plants along with complete color removal. Thus, present study confers the potential applicability of E. crassipes and P. stratiotes plants for textile dye removal and release to the environment without further treatment.

Degradation of moxifloxacin by ionizing radiation and toxicity assessment

The gamma ray induced degradation of moxifloxacin in aqueous media has been evaluated. The drug solutions (50 & 100 mg/L) were irradiated to absorbed doses of 0.3, 0.6, 0.9, 1.2, 1.5, 2, 3 and 4 kGy using Cs-137 gamma radiation source. The parameters such as drug initial concentration, oxidant (H2O2) concentration and gamma ray absorbed doses were optimized. The efficiency of Advanced oxidation processes (AOP) was evaluated on the basis of degradation, reduction in chemical oxygen demand (COD) and toxicity reduction of the drug. The maximum degradation of 94.01 and 88.30% was achieved when drug solutions were exposed to gamma irradiation absorbed dose of 4 kGy which enhanced to 100 and 99.06% in the presence of H2O2 (0.5 mL/L) for 50 and 100 mg/L respectively. A significant reduction in COD 72 and 75% for 50 mg/L while 65 and 69% in case of 100 mg/L was noted using gamma and gamma/H2O2 respectively at absorbed dose of 4 kGy. The parameters such as dose constant (k), removal efficiency (G-value), gamma ray absorbed doses required for 50, 90 and 99% degradation (D 0.50, D 0.90 and D 0.99) have been calculated. The radiolytic degradation was monitored by UV–Vis spectrophotometer and HPLC, FT-IR studies were performed to investigate the change in functional groups before and after treatment, while GC-MS analysis was carried out to monitor intermediates/degraded end-products. The FT-IR spectra has shown complete destruction of aromatic rings after radiation treatment but a minor peak appeared at 1216 cm−1 corresponding to CO stretching. The GC-MS study for the drug samples treated with gamma/H2O2 has shown no any significant peak which confirms the complete degradation. The cytotoxicity of treated samples was carried out by hemolytic assay and mutagenicity using Ames test before and after each treatment. The hemolytic test showed 73.92% hemolysis, while gamma/H2O2 treatment reduced the mutagenicity to 74.08 and 65.66% against TA98 and TA100 bacterial strains respectively. The response surface methodology (RSM) was employed to optimize the data. The obtained data elaborate that gamma/H2O2process is promising approach for the remediation of pharmaceutical waste effluent.

Combined treatment of synthetic textile effluent using mixed azo dye by phyto and phycoremediation

Phytoremediation is one of the biological approaches for remediating textile dyeing effluents. The objective of this study is the use of Pistia stratiotes, an aquatic macrophyte, which was found to degrade the maximum of 83% of mixed azo dye. A phytoreactor was designed and constructed to scale up the process of phytoremediation by P. stratiotes to treat 40 mg/l of synthetic textile effluent. Continuous flow phytoreactor fed with 40 mg/l (cycle 1) which showed maximum decolorization of 84%, COD removal was about 61%, BOD which was reduced up to 71.9%, and TDS removal was about 72% respectively. Further to remove the residual color and toxic effects of the dyes, Phycoremediation was followed for the mixed azo dyes using the microalgae Chlorella vulgaris which showed a maximum decolorization of 99% in the batch study and 74% in the scale-up study where the treated effluent was at the most minimal discharge. Phytotoxicity tests showed 80% of germination in treated effluent, and the plants in untreated wastewater had inhibited growth that indicates only 30% of germination. Such combined biological treatment techniques were put forward to be the most eco-friendly technology, which is cost-effective and attain zero discharge of the textile effluent.

Assessment of Phytoremediation Potential of Chara vulgaris to Treat Toxic Pollutants of Textile Effluent

Textile effluent released into water bodies is prone to be toxic for aquatic flora and fauna. In the present study, the phytoremediation potential of Chara vulgaris (C. vulgaris) is investigated for treatment of textile effluent. The highly concentrated and toxic textile effluent is diluted to different concentrations 10%, 25%, 50%, and 75% to check the accessibility of macroalgae to bear pollutant load of textile effluent. The toxicity of textile effluent is analysed by determining different water quality parameters, namely, pH, TDS, BOD, COD, and EC. The maximum reductions in TDS (68%), COD (78%), BOD (82%), and EC (86%) were found in the 10% concentrated textile effluent after 120 h of treatment. The highly concentrated textile effluent showed its toxic effect on macroalgae and it was found unable to show a remarkable change in water quality parameters of 75% and 100% textile effluent. The correlation coefficient values are determined using correlation matrix to identify the high correlation between different water quality parameters. The removal of toxic organic pollutants by C. vulgaris was confirmed by using UV-visible absorption spectra. Typical X-ray spectra recorded using EDXRF technique indicated the presence of heavy metals Cd in the dried sample of macroalgae after treatment which show its capability to remove toxic heavy metals from textile effluent. The reliability model has been proposed for treated textile effluents to identify percentage level of toxicity tolerance of waste water by macroalgae.

Synthesis of γ-alumina (Al2O3) nanoparticles and their potential for use as an adsorbent in the removal of methylene blue dye from industrial wastewater

Non-toxic nanomaterials have gained significant importance recently in the treatment of industrial wastewater that sometimes contains organic dyes such as methylene blue. We report here an easy approach for the synthesis of γ-alumina (Al₂O₃) nanoparticles via a method that incorporates the use of formamide and the non-ionic surfactant Tween-80. Together, formamide and Tween-80 serve as an effective precipitating agent and a convenient synthetic template, respectively, in directing the growth of the alumina nanoparticles. The morphology and structure of the nanoparticles were investigated by FT-IR, XRD, TGA, SEM, EDX, elemental mapping and TEM methods. The sizes of the nanoparticles are in the 30-50 nm range. The maximum pore size is 4.13 nm and the surface area is 112.9 m² g^-1 as determined by the Brunauer-Emmett-Teller (BET) method. The nanomaterials are excellent adsorbents for the cationic methylene blue dye from aqueous solution. The effects of pH, time, temperature and concentration on the adsorption have been examined and the adsorption capacity increased from 490 to 2210 mg g^-1 as the initial concentration was increased from 50 to 400 mg L^-1 under the following conditions: pH 9, 10 min reaction time, and 60 °C. The adsorption mechanism is considered to encompass electrostatic interactions in water between the Al₂O₃ nanoparticles and the cationic methylene blue dye. These readily made nanoparticles may well prove useful in both wastewater treatment and industrial catalysis.

In situ phytoremediation of dyes from textile wastewater using garden ornamental plants, effect on soil quality and plant growth

In situ phytoremediation of dyes from textile wastewater was carried out in a high rate transpiration system ridges (91.4 m × 1.0 m) cultivated independently with Tagetes patula, Aster amellus, Portulaca grandiflora and Gaillardia grandiflora which reduced American Dye Manufacturers Institute color value by 59, 50, 46 and 73%, respectively within 30 d compared to dye accumulated in unplanted ridges. Significant increase in microbial count and electric conductivity of soil was observed during phytoremediation. Reduction in the contents of macro (N, P, K and C), micro (B, Cu, Fe and Mn) elements and heavy metals (Cd, As, Pb and Cr) was observed in the soil from planted ridges due to phyto-treatment. Root tissues of these plants showed significant increase in the specific activities of oxido-reductive enzymes such as lignin peroxidase, laccase, veratryl alcohol oxidase, tyrosinase and azo reductase during decolorization of textile dyes from soil. Anatomical studies of plants roots revealed the occurrence of textile dyes in tissues and subsequent degradation. A minor decrease in plant growth was also observed. Overall surveillance suggests that the use of garden ornamental plants on the ridges of constructed wetland for the treatment of dyes from wastewater along with the consortia of soil microbial flora is a wise and aesthetically pleasant strategy.

Asparagus densiflorus in a vertical subsurface flow phytoreactor for treatment of real textile effluent: A lab to land approach for in situ soil remediation

This study explores the potential of Asparagus densiflorus to treat disperse Rubin GFL (RGFL) dye and a real textile effluent in constructed vertical subsurface flow (VSbF) phytoreactor; its field cultivation for soil remediation offers a real green and economic way of environmental management. A. densiflorus decolorized RGFL (40 gm L^-1) up to 91% within 48 h. VSbF phytoreactor successfully reduced American dye manufacture institute (ADMI), BOD, COD, Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) of real textile effluent by 65%, 61%, 66%, 48% and 66%, respectively within 6 d. Oxidoreductive enzymes such as laccase (138%), lignin peroxidase (129%), riboflavin reductase (111%) were significantly expressed during RGFL degradation in A. densiflorus roots, while effluent transformation caused noteworthy induction of enzymes like, tyrosinase (205%), laccase (178%), veratryl oxidase (52%). Based on enzyme activities, UV-vis spectroscopy, FTIR and GC-MS results; RGFL was proposed to be transformed to 4-amino-3- methylphenyl (hydroxy) oxoammonium and N, N-diethyl aniline. Anatomical study of the advanced root tissue of A. densiflorus exhibited the progressive dye accumulation and removal during phytoremediation. HepG2 cell line and phytotoxicity study demonstrated reduced toxicity of biotransformed RGFL and treated effluent by A. densiflorus, respectively. On field remediation study revealed a noteworthy removal (67%) from polluted soil within 30 d.

Biodegradation of a monochlorotriazine dye, cibacron brilliant red 3B-A in solid state fermentation by wood-rot fungal consortium, Daldinia concentrica and Xylaria polymorpha: Co-biomass decolorization of cibacron brilliant red 3B-A dye

Efficient decolorization of cibracron brilliant red 3B-A dye by novel white rot fungal consortium was studied in static and shaking conditions using solid state fermentation technology. Daldinia concentrica (DC) and Xylaria polymorpha (XP) consortium showed dye removal efficiency than the individual strains within 5 days. The enzymes analysis revealed significant inductions in laccase (84%), lignin peroxidase (78%) and manganese peroxidase (65%) by the fungal co-culture (DC + XP), Xylaria polymorpha (XP) and Daldinia concentrica (DC) respectively. Enhanced decolorization was recorded when the medium was supplemented with glucose and ammonium nitrate as carbon and nitrogen sources respectively. The GCMS and HPLC analysis of metabolites suggest the different fates of biodegradation of cibracron brilliant red 3B-A dye by DC, XP and DC + XP consortium. The isotherm and kinetic studies revealed the goodness of fit of the experimental data when subjected to Freundlich and pseudo-second order models respectively. Phytotoxicity studies revealed that the biodegradation of the cibracron brilliant red 3B-A dye by the DC + XP consortium and individual strains has also led to the detoxification of the pollutant. This study revealed the effectiveness of white rot fungi in the eco-friendly remediation of dye polluted environment.

Fabrication and Adsorption Behavior of Magnesium Silicate Hydrate Nanoparticles towards Methylene Blue

Magnesium silicate as a high-performance adsorption material has attracted increasing attention for the removal of organic dye pollution. Here, we prepared a series of magnesium silicate hydrates (MSH) in a hydrothermal route, and carefully investigated the corresponding adsorption behavior towards methylene blue (MB) as well as the effect of surface charge on adsorption capacity. The results show that surface charge plays a key role in the adsorption performance of MSH for MB, a negative surface charge density follows the increase of Si/Mg feeding ratio from 1.00 to 1.75, and furthermore the higher negative charge favors the improvement of the adsorption capacity. Among four investigated samples (MSH = 1.00, 1.25, 1.50, and 1.75), MSH-1.75 has the highest negative surface charge and shows the largest adsorption capacity for MB. For example, the equilibrium adsorption quantity is 307 mg·g^−1 for MSH-1.75, which is 35% higher than that of 227 mg·g^−1 for MSH-1.00. Besides, for MSH-1.75, the as-prepared sample with negative charge exhibits ca. 36% higher adsorption quantity compared to the sample at the zero point of charge (pH_ZPC). Furthermore, magnesium silicate hydrate material with Si/Mg feeding ratio = 1.75 demonstrates the promising removal efficiency of beyond 98% for methylene blue in 10 min, and the maximum adsorption capacity of 374 mg·g^−1 calculated from the Langmuir isotherm model.

Phytobeds with Fimbristylis dichotoma and Ammannia baccifera for treatment of real textile effluent: An in situ treatment, anatomical studies and toxicity evaluation

Fimbristylis dichotoma, Ammannia baccifera and their co-plantation consortium FA independently degraded Methyl Orange, simulated dye mixture and real textile effluent. Wild plants of F. dichotoma and A. baccifera with equal biomass showed 91% and 89% decolorization of Methyl Orange within 60h at a concentration of 50ppm, while 95% dye removal was achieved by consortium FA within 48h. Floating phyto-beds with co-plantation (F. dichotoma and A. baccifera) for the treatment of real textile effluent in a constructed wetland was observed to be more efficient and achieved 79%, 72%, 77%, 66% and 56% reductions in ADMI color value, COD, BOD, TDS and TSS of textile effluent, respectively. HPTLC, GC-MS, FTIR, UV-vis spectroscopy and activated oxido-reductive enzyme activities confirmed the phytotrasformation of parent dye in to new metabolites. T-RFLP analysis of rhizospheric bacteria of F. dichotoma, A. baccifera and consortium FA revealed the presence of 88, 98 and 223 genera which could have been involved in dye removal. Toxicity evaluation of products formed after phytotransformation of Methyl Orange by consortium FA on bivalves Lamellidens marginalis revealed less damage of the gills architecture when analyzed histologically. Toxicity measurement by Random Amplification of Polymorphic DNA (RAPD) technique revealed bivalve DNA banding pattern in treated Methyl Orange sample suggesting less toxic nature of phytotransformed dye products.

Concurrent uptake and metabolism of dyestuffs through bio-assisted phytoremediation: a symbiotic approach

Manipulation of bio-technological processes in treatment of dyestuffs has attracted considerable attention, because a large proportion of these synthetic dyes enter into natural environment during synthesis and dyeing operations that contaminates different ecosystems. Moreover, these dyestuffs are toxic and difficult to degrade because of their synthetic origin, durability, and complex aromatic molecular structures. Hence, bio-assisted phytoremediation has recently emerged as an innovative cleanup approach in which microorganisms and plants work together to transform xenobiotic dyestuffs into nontoxic or less harmful products. This manuscript will focus on competence and potential of plant-microbe synergistic systems for treatment of dyestuffs, their mixtures and real textile effluents, and effects of symbiotic relationship on plant performances during remediation process and will highlight their metabolic activities during bio-assisted phytodegradation and detoxification.

Co-plantation of aquatic macrophytes Typha angustifolia and Paspalum scrobiculatum for effective treatment of textile industry effluent

Field treatment of textile industry effluent was carried out in constructed drenches (91.4m×1.2m×0.6m; 65.8m³) planted independently with Typha angustifolia, Paspalum scrobiculatum and their co-plantation (consortium-TP). The in situ treatment of effluent by T. angustifolia, P. scrobiculatum and consortium-TP was found to decrease ADMI color value by 62, 59 and 76%, COD by 65, 63 and 70%, BOD by 68, 63 and 75%, TDS by 45, 39 and 57%, and TSS by 35, 31 and 47%, respectively within 96h. Heavy metals such as arsenic, cadmium, chromium and lead were also removed up to 28-77% after phytoremediation. T. angustifolia and P. scrobiculatum showed removal of Congo Red (100mg/L) up to 80 and 73%, respectively within 48h while consortium-TP achieved 94% decolorization. Root tissues of T. angustifolia and P. scrobiculatum revealed inductions in the activities of oxido-reductive enzymes such as lignin peroxidase (193 and 32%), veratryl alcohol oxidase (823 and 460%), laccase (492 and 182%) and azo reductase (248 and 83%), respectively during decolorization of Congo Red. Anatomical studies of roots, FTIR, HPLC, UV-vis Spectroscopy and GC-MS analysis verified the phytotransformation. Phytotoxicity studies confirmed reduced toxicity of the metabolites of Congo Red.

Detoxification of photo-catalytically treated 2-chlorophenol: optimization through response surface methodology

The present study was conducted to degrade and detoxify 2-chlorophenol (2-CP) under UV irradiation in the presence of titanium dioxide (TiO₂) and hydrogen peroxide (H₂O₂). The treatment efficiency was evaluated on the basis of degradation and cytotoxicity reduction as well as biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) removal. The process variables such as TiO₂, pH, UV irradiation time and H₂O₂ were optimized. Central composite design in combination with response surface methodology was employed to optimize the process variables. A quadratic model was proposed to predict the treatment efficiency and analysis of variance was used to determine the significance of the variables. The correlation between the experimental and predicted degradation was confirmed by the F and P values (<0.05). The coefficient of determination (R² = 0.99) were high enough to support the validity of developed model. At optimized conditions, up to 92% degradation of 2-CP was achieved with 3.5 × 10^-4 s^-1 rate constant. Significant reductions in BOD, COD and TOC values were also achieved. Cytotoxicity was evaluated using bioassays and it was observed that UV/TiO₂/H₂O₂ reduced the cytotoxicity considerably. It is concluded that UV/TiO₂/H₂O₂ could possibly be used to detoxify 2-CP in industrial wastewater.

Development of horseradish peroxidase-based cross-linked enzyme aggregates and their environmental exploitation for bioremediation purposes

In the present study, horseradish peroxidase (HRP), in-house isolated crude cocktail enzyme, from Armoracia rusticana was cross-linked using a new type of cross-linking agent, i.e., ethylene glycol-bis [succinic acid N-hydroxysuccinimide, (EG-NHS)], which is mild in nature as compared to the glutaraldehyde (GA). The HRP-immobilized cross-linked enzyme aggregates (HRP-CLEAs) were developed using a wider range of EG-NHS and notably no adverse effect was observed. In a comparative evaluation, in the case of EG-NHS, a high-level stability in the residual activity was recorded, whereas a sharp decrease was observed in the case of glutaraldehyde. Following initial cross-linker evaluation, the HRP-CLEAs were tested to investigate their bio-catalytic efficacy for bioremediation purposes using a newly developed packed bed reactor system (PBRS). A maximal of 94.26% degradation of textile-based methyl orange dye was recorded within the shortest time frame, following 91.73% degradation of basic red 9, 84.35% degradation of indigo, 81.47% degradation of Rhodamin B, and 73.6% degradation of Rhodamine 6G, respectively, under the same working environment. Notably, the HRP-CLEAs retained almost 60% of its original activity after methyl orange dye degradation in seven consecutive cycles using PBRS. Furthermore, after HRP-CLEAs-mediated treatment in the PBRS, a significant toxicity reduction in the dye samples was recorded as compared to their pristine counterparts. In conclusion, the results suggest that the newly developed HRP-CLEAs have a great potential for industrial exploitation, to tackle numerous industrial dye-based emergent pollutants.

Efficient decolorization and detoxification of textile industry effluent by Salvinia molesta in lagoon treatment

Salvinia molesta, an aquatic fern was observed to have a potential of degrading azo dye Rubine GFL up to 97% at a concentration of 100mg/L within 72h using 60±2g of root biomass. Both root as well as stem tissues showed induction in activities of the enzymes such as lignin peroxidase, veratryl alcohol oxidase, laccase, tyrosinase, catalase, DCIP reductase and superoxide dismutase during decolorization of Rubine GFL. FTIR, GC-MS, HPLC and UV-visible spectrophotometric analysis confirmed phytotransformation of the model dye into smaller molecules. Analysis of metabolites revealed breakdown of an azo bond of Rubine GFL by the action of lignin peroxidase and laccase and formation of 2-methyl-4-nitroaniline and N-methylbenzene-1, 4-diamine. Anatomical tracing of dye in the stem of S. molesta confirmed the presence of dye in tissues and subsequent removal after 48h of treatment. The concentration of chlorophyll pigments like chlorophyll a, chlorophyll b and carotenoid was observed during the treatment. Toxicity analysis on seeds of Triticum aestivum and Phaseolus mungo revealed the decreased toxicity of dye metabolites. In situ treatment of a real textile effluent was further monitored in a constructed lagoon of the dimensions of 7m×5m×2m (total surface area 35m(2)) using S. molesta for 192h. This large scale treatment was found to significantly reduce the values of COD, BOD5 and ADMI by 76%, 82% and 81% considering initial values 1185, 1440mg/L and 950 units, respectively.

Ipomoea hederifolia rooted soil bed and Ipomoea aquatica rhizofiltration coupled phytoreactors for efficient treatment of textile wastewater

Ipomoea aquatica, a macrophyte was found to degrade a highly sulfonated and diazo textile dye Brown 5R up to 94% within 72 h at a concentration of 200 mg L(-1). Induction in the activities of enzymes such as azoreductase, lignin peroxidase, laccase, DCIP reductase, tyrosinase, veratryl alcohol oxidase, catalase and superoxide dismutase was observed in leaf and root tissue in response to Brown 5R exposure. There was significant reduction in contents of chlorophyll a (25%), chlorophyll b (17%) and carotenoids (30%) in the leaves of plants. HPLC, FTIR, UV-vis spectrophotometric and HPTLC analyses confirmed the biotransformation and removal of parent dye from solution. Enzymes activities and GC-MS analysis of degradation products lead to the proposal of a possible pathway of phytotransformation of dye. The proposed pathway of dye metabolism revealed the formation of Napthalene-1,2-diamine and methylbenzene. Toxicity study on HepG2 cell lines showed a 3 fold decrease in toxicity of Brown 5R after phytoremediation by I. aquatica. Hydrophytic nature of I. aquatica leads to its exploration in a combinatorial phytoreactor with Ipomoea hederifolia soil bed system. Rhizofiltration with I. aquatica and soil bed treatment by I. hederifolia treated 510 L of effluent effectively within 72 h. I. aquatica along with I. hederifolia could decolorize textile industry effluent within 72 h of treatment as evident from the significant reductions in the values of COD, BOD, solids and ADMI. Further on field trials of treatment of textile wastewater was successfully carried out in a constructed lagoon.

Bioreactor with Ipomoea hederifolia adventitious roots and its endophyte Cladosporium cladosporioides for textile dye degradation

In vitro grown untransformed adventitious roots (AR) culture of Ipomoea hederifolia and its endophytic fungus (EF) Cladosporium cladosporioides decolorized Navy Blue HE2R (NB-HE2R) at a concentration of 20 ppm up to 83.3 and 65%, respectively within 96h. Whereas the AR-EF consortium decolorized the dye more efficiently and gave 97% removal within 36h. Significant inductions in the enzyme activities of lignin peroxidase, tyrosinase and laccase were observed in roots, while enzymes like tyrosinase, laccase and riboflavin reductase activities were induced in EF. Metabolites of dye were analyzed using UV-vis spectroscopy, FTIR and gas chromatography-mass spectrometry. Possible metabolic pathways of NB-HE2R were proposed with AR, EF and AR-EF systems independently. Looking at the superior efficacy of AR-EF system, a rhizoreactor was developed for the treatment of NB-HE2R at a concentration of 1000 ppm. Control reactor systems with independently grown AR and EF gave 94 and 85% NB-HE2R removal, respectively within 36h. The AR-EF rhizoreactor, however, gave 97% decolorization. The endophyte colonization additionally increased root and shoot lengths of candidate plants through mutualism. Combined bioreactor strategies can be effectively used for future eco-friendly remediation purposes.

The effect of Funnelliformis mosseae inoculation on the phytoremediation of atrazine by the aquatic plant Canna indica L. var. flava Roxb

Funnelliformis mosseaeinoculation exhibited a beneficial effect on the phytoremediation of atrazine in water by the aquatic plantCanna indicaL.

Gamma radiation/H2O2 treatment of a nonylphenol ethoxylates: Degradation, cytotoxicity, and mutagenicity evaluation

Gamma radiation/H2O2 treatment of nonylphenol polyethoxylates (NPEO) was performed and treatment effect was evaluated on the basis of degradation, chemical oxygen demand (COD) and total organic carbon (TOC), and toxicity reduction efficiencies. The radiolytic by-products were determined by Fourier Transform Infrared Spectroscopy (FTIR), High-Performance Liquid Chromatography (HPLC), and Gas Chromatography-Mass Spectrometry (GC-MS) techniques. Low mass carboxylic acids, aldehyde, ketone, and acetic acid were identified as the by-products of the NPEO degradation. NPEO sample irradiated to the absorbed dose of 15 kGy/4.58% H2O2 showed more than 90% degradation. Allium cepa (A. cepa), brine shrimp, heamolytic tests were used for cytotoxicity study, while mutagenicity was evaluated through Ames test (TA98 and TA100 strains) of treated and un-treated NPEO. The reductions in COD and TOC were greater than 70% and 50%, respectively. Gamma radiation/H2O2 treatment revealed a considerable reduction in cytotoxicity and mutagenicity. A. cepa, heamolytic and shrimp assays showed cytotoxicity reduction up to 68.65%, 77%, and 94%, respectively. The mutagenicity reduced up to 62%, 74%, and 79% (TA98) and 68%, 78%, and 82% (TA100), respectively of NPEO-6, NPEO-9, and NPEO-30 irradiated to the absorbed dose of 15 kGy/4.58% H2O2. NPEO-6 detoxified more efficiently versus NPEO-9 and NPEO-30 and results showed that Gamma radiation/H2O2 treatment has the potential to mineralize and detoxify NPEO.

Dye decolorization and detoxification potential of Ca-alginate beads immobilized manganese peroxidase

Background

In view of compliance with increasingly stringent environmental legislation, an eco-friendly treatment technology of industrial dyes and effluents is a major environmental challenge in the color industry. In present study, a promising and eco‐friendly entrapment approach was adopted to immobilize purified manganese peroxidase (MnP) produced from an indigenous strain of Ganoderma lucidum IBL-05 on Ca-alginate beads. The immobilized MnP was subsequently used for enhanced decolorization and detoxification of textile reactive dyes).

Results

MnP isolated from solid-state culture of G. lucidum IBL-05, presented highest immobilization yield (83.9 %) using alginate beads prepared at optimized conditions of 4 % (w/v) sodium alginate, 2 % (w/v) Calcium chloride (CaCl₂) and 0.5 mg/ml enzyme concentration. Immobilization of MnP enhanced optimum temperature but caused acidic shift in optimum pH of the enzyme. The immobilized MnP showed optimum activity at pH 4.0 and 60 °C as compared to pH 5.0 and 35 °C for free enzyme. The kinetic parameters K_m and V_max of MnP were significantly improved by immobilization. The enhanced catalytic potential of immobilized MnP led to 87.5 %, 82.1 %, 89.4 %, 95.7 % and 83 % decolorization of Sandal-fix Red C₄BLN, Sandal-fix Turq Blue GWF, Sandal-fix Foron Blue E₂BLN, Sandal-fix Black CKF and Sandal-fix Golden Yellow CRL dyes, respectively. The insolubilized MnP was reusable for 7 repeated cycles in dye color removal. Furthermore, immobilized MnP also caused a significant reduction in biochemical oxygen demand (BOD) (94.61-95.47 %), chemical oxygen demand (COD) (91.18-94.85 %), and total organic carbon (TOC) (89.58-95 %) of aqueous dye solutions.

Conclusions

G. lucidum MnP was immobilized in Ca-alginate beads by entrapment method to improve its practical effectiveness. Ca-alginate bound MnP was catalytically more vigorous, thermo-stable, reusable and worked over wider ranges of pH and temperature as compared to its free counterpart. Results of cytotoxicity like hemolytic and brine shrimp lethality tests suggested that Ca-alginate immobilized MnP may effectively be used for detoxification of dyes and industrial effluents.

Phytoremediation of sulfonated Remazol Red dye and textile effluents by Alternanthera philoxeroides: An anatomical, enzymatic and pilot scale study

Alternanthera philoxeroides Griseb. a macrophyte was found to degrade a highly sulfonated textile dye Remazol Red (RR) completely within 72 h at a concentration of 70 mg L(-1). An induction in the activities of azoreductase and riboflavin reductase was observed in root and stem tissues; while the activities of lignin peroxidase, laccase and DCIP reductase were induced in leaf tissues. Some enzymes namely tyrosinase, veratryl alcohol oxidase, catalase and superoxide dismutase displayed an increase in their activity in all the tissues in response of 72 h exposure to Remazol Red. There was a marginal reduction in contents of chlorophyll a (20%), chlorophyll b (5%) and carotenoids (16%) in the leaves when compared to control plants. A detailed anatomical study of the stem during uptake and treatment revealed a stepwise mechanism of dye degradation. UV-vis spectrophotometric and high performance thin layer chromatographic analyses confirmed the removal of parent dye from solution. Based on the enzymes activities and gas chromatography-mass spectroscopic analysis of degradation products, a possible pathway of phytotransformation of RR was proposed which revealed the formation of 4-(phenylamino)-1,3,5-triazin-2-ol, naphthalene-1-ol and 3-(ethylsulfonyl)phenol. Toxicity study on Devario aequipinnatus fishes showed that the anatomy of gills of fishes exposed to A. philoxeroides treated RR was largely protected. The plants were further explored for rhizofiltration experiments in a pilot scale reactor. A. philoxeroides could decolorize textile industry effluent of varying pH within 96 h of treatment which was evident from the significant reductions in the values of American dye manufacturers' institute color, chemical oxygen demand, biological oxygen demand, total dissolved and total suspended solids.

Phytoremediation of textile dyes and effluents: Current scenario and future prospects

Phytoremediation has emerged as a green, passive, solar energy driven and cost effective approach for environmental cleanup when compared to physico-chemical and even other biological methods. Textile dyes and effluents are condemned as one of the worst polluters of our precious water bodies and soils. They are well known mutagenic, carcinogenic, allergic and cytotoxic agents posing threats to all life forms. Plant based treatment of textile dyes is relatively new and hitherto has remained an unexplored area of research. Use of macrophytes like Phragmites australis and Rheum rhabarbarum have shown efficient removal of Acid Orange 7 and sulfonated anthraquinones, respectively. Common garden and ornamental plants namely Aster amellus, Portulaca grandiflora, Zinnia angustifolia, Petunia grandiflora, Glandularia pulchella, many ferns and aquatic plants have also been advocated for their dye degradation potential. Plant tissue cultures like suspension cells of Blumea malcolmii and Nopalea cochenillifera, hairy roots of Brassica juncea and Tagetes patula and whole plants of several other species have confirmed their role in dye degradation. Plants' oxidoreductases such as lignin peroxidase, laccase, tyrosinase, azo reductase, veratryl alcohol oxidase, riboflavin reductase and dichlorophenolindophenol reductase are known as key biodegrading enzymes which break the complex structures of dyes. Schematic metabolic pathways of degradation of different dyes and their environmental fates have also been proposed. Degradation products of dyes and their fates of metabolism have been reported to be validated by UV-vis spectrophotometry, high performance liquid chromatography, high performance thin layer chromatography, Fourier Transform Infrared Spectroscopy, gas chromatograph-mass spectroscopy and several other analytical tools. Constructed wetlands and various pilots scale reactors were developed independently using the plants of P. australis, Portulaca grandiflora, G. pulchella, Typha domingensis, Pogonatherum crinitum and Alternanthera philoxeroides. The developed phytoreactors gave noteworthy treatments, and significant reductions in biological oxygen demand, chemical oxygen demand, American Dye Manufacturers Institute color removal value, total organic carbon, total dissolved solids, total suspended solids, turbidity and conductivity of the dye effluents after phytoremediation. Metabolites of dyes and effluents have been assayed for phytotoxicity, cytotoxicity, genotoxicity and animal toxicity and were proved to be non/less toxic than untreated compounds. Effective strategies to handle fluctuating dye load and hydraulics for in situ treatment needs scientific attention. Future studies on development of transgenic plants for efficacious phytodegradation of textile dyes should be focused.

Sandal reactive dyes decolorization and cytotoxicity reduction using manganese peroxidase immobilized onto polyvinyl alcohol-alginate beads

Background

Fungal manganese peroxidases (MnPs) have great potential as bio-remediating agents and can be used continuously in the immobilized form like many other enzymes.

Results

In the present study, purified manganese peroxidase (MnP) enzyme isolated from Ganoderma lucidum IBL-05 was immobilized onto polyvinyl alcohol-alginate beads and investigated its potential for the decolorization and detoxification of new class of reactive dyes and textile wastewater. The optimal conditions for MnP immobilization were 10 % (w/v) PVA, 1.5 % sodium alginate, 3 % boric acid and 2 % CaCl₂ solution. The optimum pH, temperature and kinetic parameters (K_m and V_max) for free and immobilized MnP were found to be significantly altered after immobilization. The immobilized MnP showed high decolorization efficiency for Sandal reactive dyes (78.14–92.29 %) and textile wastewater (61–80 %). Reusability studies showed that after six consecutive dye decolorization cycles, the PVA coupled MnP retained more than 60 % of its initial activity (64.9 % after 6th cycle form 92.29 % in 1st cycle) for Sandal-fix Foron Blue E₂BLN dye. The water quality assurance parameters (BOD, COD and TOC) and cytotoxicity (haemolytic and brine shrimp lethality tests) studies before and after treatment were employed and results revealed that both the dyes aqueous solution and textile wastewater were cytotoxic that reduced significantly after treatment.

Conclusions

The decolorization and cytotoxicity outcomes indicated that immobilized MnP in PVA–alginate beads can be efficiently exploited for industrial and environmental applications, especially for remediation of textile dyes containing wastewater effluents. Graphical abstract

Biodegradation of heptadecane in hydrocarbon polluted dune sands using a newly-isolated thermophilic bacterium, Brevibacillus borstelensis TMU30: statistical evaluation and process optimization

An enrichment culture was established to isolate a thermophilic hydrocarbon-degrading bacterium from contaminated soil samples from the Tehran Petroleum Refinery.

Textile dye degradation potential of plant laccase significantly enhances upon augmentation with redox mediators

A redox mediator significantly enhances the textile dye degradation potential of plant laccase.

Dye–collagen interactions. Mechanism, kinetic and thermodynamic analysis

Dye–collagen interactions. Mechanism, kinetic and thermodynamic analysis.