Sustainable Durio zibethinus-Derived Biosorbents for Congo Red Removal from Aqueous Solution: Statistical Optimization, Isotherms and Mechanism Studies

Cloning and characterization of FMN-dependent azoreductases from textile industry effluent identified through metagenomic sequencing

Azo dyes, when released untreated in the environment, cause detrimental effects on flora and fauna. Azoreductases are enzymes capable of cleaving commercially used azo dyes, sometimes in less toxic by-products which can be further degraded via synergistic microbial cometabolism. In this study, azoreductases encoded by FMN1 and FMN2 genes were screened from metagenome shotgun sequences generated from the samples of textile dye industries' effluents, cloned, expressed, and evaluated for their azo dye decolorization efficacy. At pH 7 and 45°C temperature, both recombinant enzymes FMN1 and FMN2 were able to decolorize methyl red at 20 and 100 ppm concentrations, respectively. FMN2 was found to be more efficient in decolorization/degradation of methyl red than FMN1. This study offers valuable insights into the possible application of azoreductases to reduce the environmental damage caused by azo dyes, with the hope of contributing to sustainable and eco-friendly practices for the environment management. This enzymatic approach offers a promising solution for the bioremediation of textile industrial effluents. However, the study acknowledges the need for further process optimization to enhance the efficacy of these enzymes in large-scale applications.Implications: The study underscores the environmental hazards associated with untreated release of azo dyes into the environment and emphasizes the potential of azoreductases, specifically those encoded by FMN1 and FMN2 genes, to mitigate the detrimental effects. The study emphasizes the ongoing commitment to refining and advancing the enzymatic approach for the bioremediation of azo dye-containing effluents, marking a positive stride toward more sustainable industrial practices.

Comparative analysis of the equilibrium, kinetics, and characterization of the mechanism of rapid adsorption of Congo red on nano-biosorbents based on agricultural waste in industrial effluents

This study aims to remove Congo red dye from industrial effluent using economical agriculturally-based nano-biosorbents like magnetic orange peel, peanut shells, and tea waste. The nano-biosorbents were characterized by various analytical techniques like SEM, FT-IR, BET and XRD. The highest adsorption capacity was obtained under the following ideal conditions: pH = 6 (orange peel and peanut shells), pH = 3 (tea waste), and dosages of nano-biosorbents with varying timeframes of 50 min for tea waste and peanut shells and 30 min for orange peel. The study found that tea waste had the highest removal rate of 94% due to its high porosity and responsible functional groups, followed by peanut shells at 83% and orange peel at 68%. The Langmuir isotherm model was found to be the most suitable, with R2 values of 0.99 for tea waste, 0.92 for orange peel, and 0.71 for peanut shells. On the other hand, a pseudo-second-order kinetic model was very feasible, showing an R2 value of 0.99 for tea waste, 0.98 for peanut shells and 0.97 for orange peel. The significance of the current study lies in its practical application, enabling efficient waste management and water purification, thereby preserving a clean and safe environment.

Utilization of Low Cost Biofertilizers for Adsorptive Removal of Congo Red Dye

Presence of colors, organic surface finishing agents and surfactants in textile industry effluent makes it highly detrimental for surrounding environment. Hence the effluent from textile industry needs treatment for removal of these colors, organic and inorganic components before its disposal. Hence applicability of low cost and environmental friendly biosorbents, Azospirillium biofertilizer and Rhizobium biofertilizer were investigated for removal of Congo red dye. Batch experimentation was carried out to check operating parameters like, temperature, dose of adsorbent, pH, agitation speed, contact time and initial concentration. The biosorption capacity for Congo red dye was 67.114 and 101.01 mg/g, for Azospirillium biofertilizer and Rhizobium biofertilizer, respectively at optimized parameters. RL factor was 0.558 and 0.568 for Azospirillium biofertilizer and Rhizobium biofertilizer. The data showed combination of interaction-based separation through better fitting of Langmuir isotherm compared to Freundlich. Its separation is well described by Pseudo-second order and intraparticle diffusion model. Adsorption was favorable at lower temperature suggesting exothermic and spontaneous nature. Reusability for Azospirillium biofertilizer and Rhizobium biofertilizer was checked for 25 mg/land. While the biological nature of Azospirillium and Rhizobium biofertilizer makes removal of Congo red dye environmentally benign.

Adsorptive removal of Safranine T dye from aqueous solutions using sodium alginate-Festuca arundinacea seeds bio-composite microbeads

In this study, composite microbeads were prepared using Festuca arundinacea seeds and sodium alginate biopolymer at different ratios and utilized as sorbents for the sorption of Safranine T from wastewater. The sorbents were characterized by FTIR, SEM, XRD, and BET analysis. According to BET analysis, the specific surface area of the adsorbents was calculated to be 10.99 m2/g and the surface was found to be mesoporous. The optimum conditions for adsorption studies including initial pH (2-12), concentration (10-50 mg/L), contact time (0-150 min), and adsorbent mass (0.05 g/50 mL-0.25 g/50 mL) were determined at 25 °C. The raw data obtained from sorption tests were applied to Freundlich, Langmuir-1, Langmuir-2, Langmuir-3, Langmuir-4, Temkin, Toth, and Koble-Corrigan isotherm models. The best results were obtained from the Langmuir-2 and accordingly the qm values were calculated as 454.54, 833.33, and 625.00 mg/g for FA, FA-SA-20, and FA-SA-30 at 25 °C, respectively. Adsorption kinetic data illustrated that the process followed the PSO model. Reusability and desorption studies were performed for composite microbeads. Additionally, the thermodynamic studies were performed at 25, 35 and 45 °C. Considering all these results, it was seen that the FA-SA-20 composite had the highest adsorption capacity and the best desorption efficiency.

Assessment of Ismailia Canal for irrigation purposes by water quality indices

Ismailia Canal is one of the significant streams of the Nile River in Egypt. The study aimed to determine the water quality of Ismailia Canal based on the regional and seasonal variability of physicochemical parameters, irrigation criteria, and the irrigation water quality index (IWQI). It was observed that the physicochemical parameters were within the acceptable FAO irrigation limits. All cations and anions values were within the acceptable FAO limits for irrigation, except the potassium (K⁺) concentrations were over the permissible irrigation limits. The one-way analysis of variance (ANOVA) suggested a significant seasonal variation in the canal's water quality concerning all parameters (p value ˂ 0.05). However, the regional variation among various sites was statistically insignificant (p value > 0.05). Statistical analysis was used to calculate the correlation coefficient between different parameters, and the study showed highly significant correlation coefficients between different pairs of water quality parameters. The correlation matrix showed that the pH significantly affected IWQI (r = 0.661). The irrigation criterion values for Ismailia Canal were good, and the WQI levels for irrigation utilization at all studied sites were satisfactory. Deterioration of water quality may occur due to industrial, municipal, and agricultural activities. Drainage water should be treated before being mixed with irrigation water to improve its suitability for irrigation.

Bacillus subtilis: As an Efficient Bacterial Strain for the Reclamation of Water Loaded with Textile Azo Dye, Orange II

The azo dye orange II is used extensively in the textile sector for coloring fabrics. High concentrations of it are released into aqueous environments through textile effluents. Therefore, its removal from textile wastewater and effluents is necessary. Herein, initially, we tested 11 bacterial strains for their capabilities in the degradation of orange II dye. It was revealed in the preliminary data that B. subtilis can more potently degrade the selected dye, which was thus used in the subsequent experiments. To achieve maximum decolorization, the experimental conditions were optimized whereby maximum degradation was achieved at: a 25 ppm dye concentration, pH 7, a temperature of 35 °C, a 1000 mg/L concentration of glucose, a 1000 mg/L urea concentration, a 666.66 mg/L NaCl concentration, an incubation period of 3 days, and with hydroquinone as a redox mediator at a concentration of 66.66 mg/L. The effects of the interaction of the operational factors were further confirmed using response surface methodology, which revealed that at optimum conditions of pH 6.45, a dye concentration of 17.07 mg/L, and an incubation time of 9.96 h at 45.38 °C, the maximum degradation of orange II can be obtained at a desirability coefficient of 1, estimated using the central composite design (CCD). To understand the underlying principles of degradation of the metabolites in the aliquot mixture at the optimized condition, the study steps were extracted and analyzed using GC-MS(Gas Chromatography Mass Spectrometry), FTIR(Fourier Transform Infrared Spectroscopy), ¹H and carbon 13 NMR(Nuclear Magnetic Resonance Spectroscopy). The GC-MS pattern revealed that the original dye was degraded into o-xylene and naphthalene. Naphthalene was even obtained in a pure state through silica gel column isolation and confirmed using ¹H and ¹³C NMR spectroscopic analysis. Phytotoxicity tests on Vigna radiata were also conducted and the results confirmed that the dye metabolites were less toxic than the parent dye. These results emphasize that B. subtilis should be used as a potential strain for the bioremediation of textile effluents containing orange II and other toxic azo dyes.

An Overview of Characterisation, Utilisation, and Leachate Analysis of Clinical Waste Incineration Ash

As industrial globalisation and waste output continue to grow, solid waste management is one of the most pressing worldwide environmental challenges. Solid wastes include both the heterogeneous mass of urban throwaways and the homogeneous accumulations of agricultural, industrial, and mineral wastes. Clinical waste (CW) has a significant negative influence on both human health and the environment. To dispose hazardous CW, a proper waste management system should be necessary, and incineration should be the best possible option for reducing the volume of this hazardous waste. Incineration is being developed in Malaysia as a means of disposing clinical and hazardous waste. Currently, 170 common CW treatment facilities with 140 incinerators are accessible around the country. The combustion procedure kills pathogens and reduces waste volume and weight, but it leaves a solid residue known as clinical waste ash (CWA), which raises heavy metal, inorganic salt, and organic compound levels in the environment. Because metals are not eliminated during incineration, dumping CWA in a landfill could contaminate groundwater. Leachate is the liquid created when waste decomposes in a landfill and water filters through it. The most common method of disposing of CW ashes is to transfer them to a landfill. Landfills should install a top cover after closure for hazardous waste landfills. Due to a lack of space and the high expense of land disposal, recycling technologies and the reuse of ash in various systems have developed. Clinical waste incineration fly ash (CWIFA), a solid waste substance from CW incineration, typically includes mobile heavy metals and can cause significant pollution when reused. The standard requirement for removing CWIFA in dumpsites should be below the metal limit stated by the U.S. Environmental Protection Agency (USEPA). Much recent research on the usage of CWIFA has concentrated on mitigating their effects on the environment. Several studies have confirmed the utilisation of CWIFA in the construction field and agriculture to reduce the leaching of its hazardous components into the environment. Compressive strength decreased with the percentage amount of CWIFA due to the substitution of cement with CWIFA. CWIFA mix with 20% cement is the broad-scale application of CWIFA for geotechnical constructions. Heavy metals (Cd, Cu, Ni, Pb, and Zn) are strongly immobilised by the cementitious matrix. Solidification/stabilisation (S/S) materials can be dumped in landfills with less environmental protection than untreated waste. When utilising a CWIFA in mortar, the primary environmental concern is if any harmful materials leach out during the initial curing process or throughout the life of the mortar. Toxicity characteristic of leaching procedure (TCLP) analysis of all CWIFA specimens found amounts of heavy metals below regulatory limits. Solidification of waste with cement and solidified waste has become a popular way of minimising the atmosphere's emissions. The amount of CWIFA generated is expected to increase nationally and globally. There is an immediate need for further evaluation of ash leachate investigations for proper disposal and usage of ash in construction materials.

Biological Degradation of the Azo Dye Basic Orange 2 by Escherichia coli: A Sustainable and Ecofriendly Approach for the Treatment of Textile Wastewater

In this study, initially 11 different bacterial strains were tested for the degradation capabilities against Basic Orange 2 dye. In initial screening with 78.90% degradation activity, Escherichia coli emerged as the most promising strain to degrade the selected dye, and was then employed in subsequent experiments. For further enhancing the degradation capability of selected bacteria, the effects of various physicochemical parameters were also evaluated. Among the tested parameters, 20 ppm dye concentration, 1666 mg/L glucose concentration, a temperature of 40 °C, 666 mg/L sodium chloride concentration, pH 7, 1000 mg/L urea concentration, a 3-day incubation period and the use of sodium benzoate as a redox mediator (666 mg/L) were found to be ideal conditions to get the highest decolorization/degradation activities. Finally, all the mentioned parameters were combined in a single set of experiments, and the decolorization capacity of the bacteria was enhanced to 89.88%. The effect of pH, dye concentration, incubation time and temperature were found to be responsible for the optimum degradation of dye (p < 0.05), as predicted from the ANOVA (analysis of variance) of the response surface methodology. The metabolites were collected after completion of the process and characterized through Fourier transform irradiation (FTIR) and gas chromatography mass spectrometry (GC-MS). From the data obtained, a proposed mechanism was deduced where it was assumed that the azo bond of the dye was broken by the azoreductase enzyme of the bacteria, resulting in the formation of aniline and 3, 4-diaminobezeminium chloride. The aniline was then further converted to benzene by deamination by the action of the bacterial deaminase enzyme. The benzene ring, after subsequent methylation, was transformed into o-xylene, while 3, 4-diaminobezeminium chloride was converted to p-xylene by enzymatic action. These findings suggest that Escherichia coli is a capable strain to be used in the bioremediation of textile effluents containing azo dyes. However, the selected bacterial strain may need to be further investigated for other dyes as well.

Removal of Organic Dyes from Aqueous Solutions by Activated Carbons Prepared from Residue of Supercritical Extraction of Marigold

In the present work, we reported on the efficiency of the removal of organic dyes by adsorption on activated carbons prepared from the residue of supercritical extraction of marigold. The performance of adsorbents prepared was tested towards methyl red, methylene blue, malachite green, and crystal violet at room temperature. The effects of carbonization (500 and 700 °C) and activation (700 and 800 °C) temperatures, textural parameters, and acid-base character of the adsorbent surface on the sorption properties of the activated carbons were established. Activated carbons are characterized by low developed specific surface area, from 2 to 206 m²/g, and have a basic character of the surface (pH of carbons water extracts ranging from 10.4 to 11.2). Equilibrium adsorption isotherms were investigated. The equilibrium data were analyzed in the Langmuir, Freundlich, and Temkin models. The adsorption capacities of activated carbons studied varied from 47.62 to 102.43 mg/g towards methyl red, 53.14 to 139.72 mg/g towards methyl red, 425.46 to 622.80 towards malachite green and 155.91 to 293.75 mg/g towards crystal violet, from their water solutions. Kinetics of the adsorption of the organic dyes studied were found to be described by the pseudo-second-order model. It was proven that through the physical activation of the residue of supercritical extraction of marigold, it is possible to obtain carbonaceous materials of very high adsorption capacity towards organic pollutants.

Porous Biomass Carbon Derived from Clivia miniata Leaves via NaOH Activation for Removal of Dye

Clivia miniata (CM), is an important ornamental plant and has been widely cultivated all over the world. However, there are no reports on Clivia miniata-based porous biomass carbon (CMBC). In this study, for the first time, CM leaves were used to generate porous biomass carbon via NaOH activation. The structures and surface characteristics were determined using scanning electron microscopy, N₂ adsorption/desorption, TGA, FT-IR, X-ray diffraction, Raman and X-ray photoelectron spectra tests. CMBC has a large SSA (2716 m²/g) and a total pore volume of 1.95 cm³/g. To test the adsorption performance via adsorption experiments, the cationic and synthetic dye, malachite green (MG), was utilized as the adsorption model. The CMBC had a greatest adsorption capacity of 2622.9 mg/g at a pH value of 8 and had a fastest adsorption capacity of 1161.7 mg/g in the first 5 min. To explain MG adsorption into CMBC, the Freundlich isotherm and the pseudo-second-order kinetic model were used. The adsorption mechanism of MG was also investigated. After 10 cycles, the adsorption efficiency of CMBC to MG could still reach 85.3%. In summary, CMBC has excellent potential in dyeing wastewater pollution treatment.