Efficiency of decolorization of different dyes using fungal biomass immobilized on different solid supports

Rhodamine B, an organic environmental pollutant induces reproductive toxicity in parental and teratogenicity in F1 generation in vivo

This study investigated the reproductive toxicity of rhodamine B in zebrafish and its transgenerational effects on the F1 generation. In silico toxicity predictions revealed high toxicity of rhodamine B, mainly targeting pathways associated with the reproductive and endocrine systems. In vivo experiments on zebrafish demonstrated that rhodamine B exposure at a concentration of 1.5 mg/L led to significant impairments in fecundity parameters, particularly affecting females. Histopathological analysis revealed distinct changes in reproductive organs, further confirming the reproductive toxicity of rhodamine B, with females being more susceptible than males. Gene expression studies indicated significant suppression of genes crucial for ovulation in rhodamine B-treated female fish, highlighting hormonal imbalance as a potential mechanism of reproductive toxicity. Furthermore, bioaccumulation studies showed the presence of rhodamine B in both adult fish gonads and F1 generation samples, suggesting transgenerational transfer of the dye. Embryotoxicity studies on F1 generation larvae demonstrated reduced survival rates, lower hatching rates, and increased malformations in groups exposed to rhodamine B. Moreover, rhodamine B induced oxidative stress in F1 generation larvae, as evidenced by elevated levels of reactive oxygen species and altered antioxidant enzyme activity. Neurotoxicity assessments revealed reduced acetylcholinesterase activity, indicating potential neurological impairments in F1 generation larvae. Additionally, locomotory defects and skeletal abnormalities were observed in F1 generation larvae exposed to rhodamine B. This study provides comprehensive evidence of the reproductive toxicity of rhodamine B in adult zebrafish and its transgenerational effects on the F1 generation.

Microalgal and activated sludge processing for biodegradation of textile dyes

The textile industry contributes substantially to water pollution. To investigate bioremediation of dye-containing wastewater, the decolorization and biotransformation of three textile azo dyes, Red HE8B, Reactive Green 27, and Acid Blue 29, were considered using an integrated remediation approach involving the microalga Chlamydomonas mexicana and activated sludge (ACS). At a 5 mg L-1 dye concentration, using C. mexicana and ACS alone, decolorization percentages of 39%-64% and 52%-54%, respectively, were obtained. In comparison, decolorization percentages of 75%-79% were obtained using a consortium of C. mexicana and ACS. The same trend was observed for the decolorization of dyes at higher concentrations, but the potential for decolorization was low. The toxic azo dyes adversely affect the growth of microalgae and at high concentration 50 mg L-1 the growth rate inhibited to 50-60% as compared to the control. The natural textile wastewater was also treated with the same pattern and got promising results of decolorization (90%). Moreover, the removal of BOD (82%), COD (72%), TN (64%), and TP (63%) was observed with the consortium. The HPLC and GC-MS confirm dye biotransformation, revealing the emergence of new peaks and the generation of multiple metabolites with more superficial structures, such as N-hydroxy-aniline, naphthalene-1-ol, and sodium hydroxy naphthalene. This analysis demonstrates the potential of the C. mexicana and ACS consortium for efficient, eco-friendly bioremediation of textile azo dyes.

Biodegradation and detoxification study of triphenylmethane dye (Brilliant green) in a recirculating packed-bed bioreactor by bacterial consortium

In the last few decades, Brilliant green (BG) dye is widely employed to colour the fabric materials in various industries (e.g. textile, pulp and paper, etc.). The wastewater containing BG dye emerges as a major challenge among the researchers due to its toxic, mutagenic, and carcinogenic effects on human beings and marine life. In this context, the present study is mainly focused on the biodegradation of BG dye present in wastewater. The biodegradation of BG dye was performed in an indigenously designed recirculating packed bed bioreactor (RPBBR). Modified Polypropylene-Polyurethane foam (PP-PUF), a support packing material, was immobilised with a newly isolated bacterial consortium of Enterobacter asburiae strain SG43 (BGT1) and Alcaligenes sp. SY1 (BGT2). The bioreactor was operated under various organic loading rates (OLRs) of 2.7, 1.27, 0.93, 0.71, and 0.53 kg COD/m3.d-1 with a hydraulic retention time (HRT) of 4 days. The bioreactor exhibited the maximum BG dye removal efficiency of 91%. Proton Nuclear Magnetic Resonance (1H NMR), UV-Vis spectroscopy, Gas chromatography-mass spectrometry (GC-MS), and Fourier Transform Infrared Spectroscopy (FTIR) depicted the biodegradation of BG dye. Phaseolus mungo seeds germinated in BG dye biodegraded wastewater was significantly high (83.56%) than the untreated wastewater (32.4%), which was reasonably subjected to the detoxification of treated wastewater.

Harnessing the potential of white rot fungi and ligninolytic enzymes for efficient textile dye degradation: A comprehensive review

The contamination of wastewater with textile dyes has emerged as a pressing environmental concern due to its persistent nature and harmful effects on ecosystems. Conventional dye treatment methods have proven inadequate in effectively breaking down complex dye molecules. However, a promising alternative for textile dye degradation lies in the utilization of white rot fungi, renowned for their remarkable lignin-degrading capabilities. This review provides a comprehensive analysis of the potential of white rot fungi in degrading textile dyes, with a particular focus on their ligninolytic enzymes, specifically examining the roles of lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase in the degradation of lignin and their applications in textile dye degradation. The primary objective of this paper is to elucidate the enzymatic mechanisms involved in dye degradation, with a spotlight on recent research advancements in this field. Additionally, the review explores factors influencing enzyme production, including culture conditions and genetic engineering approaches. The challenges associated with implementing white rot fungi and their ligninolytic enzymes in textile dye degradation processes are also thoroughly examined. Textile dye contamination poses a significant environmental threat due to its resistance to conventional treatment methods. White rot fungi, known for their ligninolytic capabilities, offer an innovative approach to address this issue. The review delves into the intricate mechanisms through which white rot fungi and their enzymes, including LiP, MnP, and laccase, break down complex dye molecules. These enzymes play a pivotal role in lignin degradation, a process that can be adapted for textile dye removal. The review also emphasizes recent developments in this field, shedding light on the latest findings and innovations. It discusses how culture conditions and genetic engineering techniques can influence the production of these crucial enzymes, potentially enhancing their efficiency in textile dye degradation. This highlights the potential for tailored enzyme production to address specific dye contaminants effectively. The paper also confronts the challenges associated with integrating white rot fungi and their ligninolytic enzymes into practical textile dye degradation processes. These challenges encompass issues like scalability, cost-effectiveness, and regulatory hurdles. By acknowledging these obstacles, the review aims to pave the way for practical and sustainable applications of white rot fungi in wastewater treatment. In conclusion, this comprehensive review offers valuable insights into how white rot fungi and their ligninolytic enzymes can provide a sustainable solution to the urgent problem of textile dye-contaminated wastewater. It underscores the enzymatic mechanisms at play, recent research breakthroughs, and the potential of genetic engineering to optimize enzyme production. By addressing the challenges of implementation, this review contributes to the ongoing efforts to mitigate the environmental impact of textile dye pollution. PRACTITIONER POINTS: Ligninolytic enzymes from white rot fungi, like LiP, MnP, and laccase, are crucial for degrading textile dyes. Different dyes and enzymatic mechanisms is vital for effective wastewater treatment. Combine white rot fungi-based strategies with mediator systems, co-culturing, or sequential treatment approaches to enhance overall degradation efficiency. Emphasize the broader environmental impact of textile dye pollution and position white rot fungi as a promising avenue for contributing to mitigation efforts. This aligns with the overarching goal of sustainable wastewater treatment practices and environmental conservation. Consider scalability, cost-effectiveness, and regulatory compliance to pave the way for sustainable applications that can effectively mitigate the environmental impact of textile dye pollution.

Optimization of dye-contaminated wastewater treatment by fungal Mycelial-light expanded clay aggregate composite

Dye-contaminated wastewaters from the printing batik industry are hazardous if discharged into the environment without any treatment. Finding an optimization and reusability assessment of a new fungal-material composite for dye-contaminated wastewater treatment is important for efficiency. The study purposes to optimize fungal mycelia Trametes hirsuta EDN 082 - light expanded clay aggregate (myco-LECA) composite for real priting batik dye wastewater treatment by using Response Surface Methodology with Central Composite Design (RSM-CCD). The factors included myco-LECA weight (2-6 g), wastewater volume (20-80 mL), and glucose concentration (0-10%) were applied for 144 h of incubation time. The result showed that the optimum condition was achieved at 5.1 g myco-LECA, at 20 mL wastewater, and at 9.1% glucose, respectively. In this condition, the decolorization values with an incubation time of 144 h were 90, 93, and 95%, at wavelengths 570, 620, and 670 nm, respectively. A reusability assessment was conducted for 19 cycles and the result showed that decolorization effectiveness was still above 96%. GCMS analysis showed the degradation of most compounds in the wastewater and the degradation products of the wastewater demonstrated detoxification against Vigna radiata and Artemia salina. The study suggests that myco-LECA composite has a good performance and therefore is a promising method for the treatment of printing batik wastewater.

Microbial biodegradation of recalcitrant synthetic dyes from textile-enriched wastewater by Fusarium oxysporum

The present study reported the improvement of biological treatment for the removal of recalcitrant dyes including aniline blue, reactive black 5, orange II, and crystal violet in contaminated water. The biodegradation efficiency of Fusarium oxysporum was significantly enhanced by the addition of mediators and by adjusting the biomass density and nutrient composition. A supplementation of 1% glucose in culture medium improved the biodegradation efficiency of aniline blue, reactive black 5, orange II, and crystal violet by 2.24, 1.51, 4.46, and 2.1 folds, respectively. Meanwhile, the addition of mediators to culture medium significantly increased the percentages of total removal for aniline blue, reactive black 5, orange II, and crystal violet, reaching 86.07%, 68.29%, 76.35%, and 95.3%, respectively. Interestingly, the fungal culture supplemented with 1% remazol brilliant blue R boosted the biodegradation up to 97.06%, 89.86%, 91.38%, and 86.67% for aniline blue, reactive black 5, orange II, and crystal violet, respectively. Under optimal culture conditions, the fungal culture could degrade these synthetic dyes concentration up to 10⁴ mg/L. The present study demonstrated that different recalcitrant dye types can be efficiently degraded using microorganism such as F. oxysporum.

Sorghum-grown fungal biocatalysts for synthetic dye degradation

The synthetic dye discharge is responsible for nearly one-fifth of the total water pollution from textile industry, which poses both environmental and public health risks. Herein, a solid substrate inoculated with fungi is proposed as an effective and environmentally friendly approach for catalyzing organic dye degradation. Pleurotus ostreatus was inoculated onto commercially available solid substrates such as sorghum, bran, and husk. Among these, P. ostreatus grown on sorghum (PO-SORG) produced the highest enzyme activity and was further tested for its dye biodegradation ability. Four dye compounds, Reactive Blue 19 (RB-19), Indigo Carmine, Acid Orange 7, and Acid Red 1 were degraded by PO-SORG with removal efficiencies of 93%, 95%, 95%, and 78%, respectively. Under more industrially relevant conditions, PO-SORG successfully degraded dyes in synthetic wastewater and in samples collected from a local textile factory, which reveals its potential for practical usage. Various biotransformation intermediates and end-products were identified for each dye. PO-SORG exhibited high stability even under relatively extreme temperatures and pH conditions. Over 85% removal of RB-19 was achieved after three consecutive batch cycles, demonstrating reusability of this approach. Altogether, PO-SORG demonstrated outstanding reusability and sustainability and offers considerable potential for treating wastewater streams containing synthetic organic dyes.

Preparation and characterization of low-cost adsorbents for the efficient removal of malachite green using response surface modeling and reusability studies

Malachite green used in textile and dyeing industries is a common persistent pollutant in wastewater and the environment causing major hazards to human health and aquatic organisms. In this study, the response surface methodology was applied to optimize the adsorptive removal of malachite green using nano-bentonite, MgO-impregnated clay, and Mucor sp. composites. The nano materials and Mucor sp. composite were characterized by FTIR, SEM and X-ray diffractometry. According to the obtained results, nano-bentonite exhibits a maximum MG adsorption efficiency of 98.6% at 35 °C, pH 7.0, 60 min contact time, 1.0 g/L adsorbent dosage, and 50 mg/L initial MG concentration. On the other hand, the maximum efficiency for MG adsorption on MgO-impregnated clay of 97.04% is observed at pH 9.0, 60 min contact time, 0.7 g/L adsorbent dosage, and 50 mg/L initial MG concentration. The Malachite green (MG) adsorption isotherm on MgO-impregnated clay corresponded with the Freundlich isotherm, with a correlation coefficient (R²) of 0.982. However, the Langmuir adsorption isotherm was a superior fit for nano-bentonite (R² = 0.992). The adsorption activities of nano-bentonite and MgO-impregnated clay were fitted into a pseudo-second-order kinetic model with R² of 0.996 and 0.995, respectively. Additionally, despite being recycled numerous times, the adsorbent maintained its high structural stability and removal effectiveness for nano-bentonite (94.5-86%) and MgO-impregnated clay (92-83%).

Decolorization of dye effluents via immobilized glycoprotein peroxidase on post-consumer polystyrene foam

Development of sustainable approaches to manage industrial wastes such as plastic waste and dye effluents is a major research endeavor, owing to escalating environmental and health concerns arising from discharge of such wastes into water bodies. In this context, this study aims to convert packaging waste of expanded polystyrene foam (EPS) into effective biocatalyst for enzymatic degradation of dye effluent. Briefly, crushed EPS were decorated with amine groups via chlorosulfonation followed by conjugation of branched polyethylenimine. Carbohydrate rich turnip peroxidase (TPOD) was purified to homogeneity from Brassic rapa roots followed by periodate oxidation to introduce reactive dialdehyde groups. Such oxidized TPOD glycoprotein was covalently immobilized on aminated EPS through Schiff base formation. Immobilized TPOD exposed noticeable tolerance toward elevated temperatures (80 °C) that qualifies it as viable biocatalyst for decolorization of dye effluents that is frequently hot. Indeed, immobilized TPOD could successfully decolorize methyl orange (90 %) and crystal violet (96 %) within 2 h. Due to the floating nature of EPS, the immobilized TPOD was simply separated by skimming and reused in fifteen subsequent catalytic cycles. Ultimately, this work demonstrates the conversion of post-consumer EPS into a value-added biocatalyst for the ecofriendly enzymatic treatment of dye effluents.

In vivo toxicity assessment of Remazol Gelb-GR (RG-GR) textile dye in zebrafish embryos/larvae (Danio rerio): Teratogenic effects, biochemical changes, immunohistochemical changes

Dyes, which are very important for various industries, have very adverse effects on the aquatic environment and aquatic life. However, there are limited studies on the toxic properties of dyes on living things. This research elucidated the sublethal toxicity of acute exposure of the textile dye remazol gelb-GR (RG-GR) using zebrafish embryos and larvae for 96 h. The 96 h-LC₅₀ for RG-GR in zebrafish embryos/larvae was determined to be 151.92 mg/L. Sublethal 96 hpf exposure was performed in RG-GR concentrations (0.5; 1.0; 10.0; 100.0 mg/L) to determine the development of toxicity in zebrafish embryos/larvae. RG-GR dye affected morphological development, and decreased heart rate, hatching, blood flow, and survival rates in zebrafish embryos/larvae. The immunopositivity of 8-hydroxy 2 deoxyguanosine (8-OHdG) in larvae exposed to RG-GR at high concentrations was found to be intense. Depending on the RG-GR dose increase, some biochemical parameters such as glutathione peroxidase (GSH) level, acetylcholinesterase (AChE) activity, catalase (CAT) activities, superoxide dismutase (SOD), and nuclear factor erythroid 2 (Nrf-2) levels were detected to be decreased in larvae, while malondialdehyde (MDA) content, nuclear factor kappa (NF-kB), tumor necrosis factor-α (TNF-α), DNA damage (8-OHdG level), interleukin-6 (IL-6) and apoptosis (Caspase-3) levels were found to be increased. The experimental results revealed that RG-GR dye has high acute toxicity on zebrafish embryo/larvae.

Textile dyeing wastewater treatment by Penicillium chrysogenum: Design of a sustainable process

In this work a parametric study and a bench bioreactor degradation test of Direct Black 22 (DB22) by Penicillium chrysogenum was performed as a first approach to an industrial application, framed within a policy of sustainable processes development. Three ancillary carbon sources and their optimum initial concentrations were studied. These were: glucose, potato starch and potato industry wastewater. Their optimum initial concentration was 6 g/L. The use of potato starch as co-substrate showed the highest decolorization rate and COD removal. Degradation of DB22 using different immobilization supports (stainless steel sponge, loofah sponge and polyethylene strips) was studied and the results showed that the time needed for the treatment decreased from 6 to 4 d. Phytotoxicity was evaluated in the final products of the immobilized cells assays, using Lactuca sativa seeds. For all treatments phytoxicity was reduced with respect to the untreated wastewater, except for the assays using polyethylene strips. Finally, the reuse of the biomass attached to different carriers and the performance of the treatment of DB22 in a 1 L bench scale bioreactor were tested. P. chrysogenum decolorized at least four sucesives reuses. The reactor assays showed a better performance of the treatment.

Role of ascomycete and basidiomycete fungi in meeting established and emerging sustainability opportunities: a review

Fungal biomass is the future's feedstock. Non-septate Ascomycetes and septate Basidiomycetes, famously known as mushrooms, are sources of fungal biomass. Fungal biomass, which on averagely comprises about 34% protein and 45% carbohydrate, can be cultivated in bioreactors to produce affordable, safe, nontoxic, and consistent biomass quality. Fungal-based technologies are seen as attractive, safer alternatives, either substituting or complementing the existing standard technology. Water and wastewater treatment, food and feed, green technology, innovative designs in buildings, enzyme technology, potential health benefits, and wealth production are the key sectors that successfully reported high-efficiency performances of fungal applications. This paper reviews the latest technical know-how, methods, and performance of fungal adaptation in those sectors. Excellent performance was reported indicating high potential for fungi utilization, particularly in the sectors, yet to be utilized and improved on the existing fungal-based applications. The expansion of fungal biomass in the industrial-scale application for the sustainability of earth and human well-being is in line with the United Nations' Sustainable Development Goals.

Biological activated carbon process for biotransformation of azo dye Carmoisine by Klebsiella spp

The feasibility of employing the biological activated carbon (BAC) process to debilitate azo dye Carmoisine by Klebsiella spp. was investigated. Plate assay revealed the capability of Klebsiella spp. for removal of Carmoisine via degradation. Kinetic parameters were measured for Carmoisine debilitation by Klebsiella spp. using the suspended anaerobic process. Two types of granular and rod-shaped activated carbon were used to form the biological beds in order to study the Carmoisine debilitation in batch processes. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to indicate the colonization and biofilm formation of bacteria grown on activated carbon particles (ACPs). Thin-layer chromatography (TLC), liquid chromatography-mass spectrometry (LC-MS), high-pressure liquid chromatography (HPLC) and biosorption studies demonstrated biotransformation of Carmoisine into its constituent aromatic amines during the Carmoisine debilitation in suspended anaerobic and BAC processes. The porosity of activated carbons, inoculation size and age of biological beds were the important factors affecting the viability of bacterial cells grown on ACPs and, consequently, the rate and efficiency of the Carmoisine debilitation process determined through spectrophotometry. The reusability of biological beds was demonstrated by conducting sequential batch experiments. In conclusion, the BAC process proved to be an efficient method for anaerobic dye degradation.

Study on the preparation conditions and degradation performance of an efficient immobilized microbial agent for marine oil pollution

In the process of handling marine oil spills accidents, the biological method has attracted wide attention due to its low cost and no secondary pollution. However, in the process of practical application, there are problems such as low microbial density and great influence of environmental factors when the oil is treated by spraying microorganisms on the sea surface. This study used immobilized microorganism technology to solve the above-mentioned problems. In this study, the bacteria immobilized on cinnamon shell (CS) with good degradation performance were obtained by optimizing preparation conditions. Under the optimal conditions of sodium alginate (SA) concentration of 4.57%, CS concentration of 1.28%, and the CaCl₂ concentration of 2.45%, the degradation rate of diesel in 5 days reached 74.04%. The reusability of immobilized microbial agents was further studied. The study designed three cycles of repeated degradation experiments. The results showed that the degradation rate of diesel can still reach 60.12% after three times of reuse, which indicated the reusability of the immobilized microbial agents was excellent. The decrease in degradation rate of diesel was mainly related to the fragmentation of immobilized microbial agents and the decrease in microbial biomass.

High Potential Decolourisation of Textile Dyes from Wastewater by Manganese Peroxidase Production of Newly Immobilised Trametes hirsuta PW17-41 and FTIR Analysis

Coloured wastewater from the textile industry is a very serious global problem. Among 16 different white-rot fungal isolates, Trametes hirsuta PW17-41 revealed high potential for decolourisation of mixed textile dyes (Navy EC-R, Ruby S3B and Super Black G) from real industrial wastewater samples. The efficiency of dye decolourisation was evaluated using the American Dye Manufacturers’ Institute (ADMI) standard methodology. The suitable support for fungal mycelium immobilisation was nylon sponges. The optimal dye decolourisation (95.39%) was achieved by using palm sugar and ammonium nitrate as carbon and nitrogen sources, respectively. The initial pH was 5 and the agitation speed was 100 rpm at 30 °C. The ADMI values of textile dyes decreased from 2475 to 114 within two days, reducing the treatment time from seven days before optimisation. The major mechanism of dye decolourisation was biodegradation, which was confirmed by UV–visible and FTIR spectra. Manganese peroxidase (MnP) (4942 U L⁻¹) was found to be the main enzyme during the decolourisation process at an initial dye concentration of 21,200 ADMI. The results indicated the strong potential of immobilised fungal cells to remove high concentrations of textile dyes from industrial wastewater and their potential ability to produce high MnP and laccase activities that can be used in further application.

Microbial Degradation of Azo Dyes: Approaches and Prospects for a Hazard-Free Conversion by Microorganisms

Azo dyes have become a staple in various industries, as colors play an important role in consumer choices. However, these dyes pose various health and environmental risks. Although different wastewater treatments are available, the search for more eco-friendly options persists. Bioremediation utilizing microorganisms has been of great interest to researchers and industries, as the transition toward greener solutions has become more in demand through the years. This review tackles the health and environmental repercussions of azo dyes and its metabolites, available biological approaches to eliminate such dyes from the environment with a focus on the use of different microorganisms, enzymes that are involved in the degradation of azo dyes, and recent trends that could be applied for the treatment of azo dyes.

Myco-remediation: A mechanistic understanding of contaminants alleviation from natural environment and future prospect

Industrialization and modernization of agricultural systems contaminated lithosphere, hydrosphere, and biosphere of the Earth. Sustainable remediation of contamination is essential for environmental sustainability. Myco-remediation is proposed to be a green, economical, and efficient technology over conventional remediation technologies to combat escalating pollution problems at a global scale. Fungi can perform remediation of pollutants through several mechanisms like biosorption, precipitation, biotransformation, and sequestration. Myco-remediation significantly removes or degrades metal metals, persistent organic pollutants, and other emerging pollutants. The current review highlights the species-specific remediation potential, influencing factors, genetic and molecular control mechanism, applicability merits to enhance the bioremediation efficiency. Structure and composition of fungal cell wall is crucial for immobilization of toxic pollutants and a subtle change on fungal cell wall structure may significantly affect the immobilization efficiency. The utilization protocol and applicability of enzyme engineering and myco-nanotechnology to enhance the bioremediation efficiency of any potential fungus was proposed. It is advocated that the association of hyper-accumulator plants with plant growth-promoting fungi could help in an effective cleanup strategy for the alleviation of persistent soil pollutants. The functions, activity, and regulation of fungal enzymes in myco-remediation practices required further research to enhance the myco-remediation potential. Study of the biotransformation mechanisms and risk assessment of the products formed are required to minimize environmental pollution. Recent advancements in molecular "Omic techniques"and biotechnological tools can further upgrade myco-remediation efficiency in polluted soils and water.

Roles and applications of enzymes for resistant pollutants removal in wastewater treatment

Resistant pollutants like oil, grease, pharmaceuticals, pesticides, and plastics in wastewater are difficult to be degraded by traditional activated sludge methods. These pollutants are prevalent, posing a great threat to aquatic environments and organisms since they are toxic, resistant to natural biodegradation, and create other serious problems. As a high-efficiency biocatalyst, enzymes are proposed for the treatment of these resistant pollutants. This review focused on the roles and applications of enzymes in wastewater treatment. It discusses the influence of enzyme types and their sources, enzymatic processes in resistant pollutants remediation, identification and ecotoxicity assay of enzymatic transformation products, and typically employed enzymatic wastewater treatment systems. Perspectives on the major challenges and feasible future research directions of enzyme-based wastewater treatment are also proposed.

Decolorization and detoxification of different azo dyes by Phanerochaete chrysosporium ME-446 under submerged fermentation

Azo dyes are widely used in the textile industry due to their resistance to light, moisture, and oxidants. They are also an important class of environmental contaminant because of the amount of dye that reaches natural water resources and because they can be toxic, mutagenic, and carcinogenic. Different technologies are used for the decolorization of wastewater containing dyes; among them, the biological processes are the most promising environmentally. The aim of this study was to evaluate the potential of Phanerochaete chrysosporium strain ME-446 to safely decolorize three azo dyes: Direct Yellow 27 (DY27), Reactive Black 5 (RB5), and Reactive Red 120 (RR120). Decolorization efficiency was determined by ultraviolet-visible spectrophotometry and the phytotoxicity of the solutions before and after the fungal treatment was analyzed using Lactuca sativa seeds. P. chrysosporium ME-446 was highly efficient in decolorizing DY27, RB5, and RR120 at 50 mg L-1, decreasing their colors by 82%, 89%, and 94% within 10 days. Removal of dyes was achieved through adsorption on the fungal mycelium as well as biodegradation, inferred by the changes in the dyes' spectral peaks. The intensive decolorization of DY27 and RB5 corresponded to a decrease in phytotoxicity. However, phytotoxicity increased during the removal of color for the dye RR120. The ecotoxicity tests showed that the absence of color does not necessarily translate to an absence of toxicity.

Simultaneous removal of Cu(II) and reactive green 6 dye from wastewater using immobilized mixed fungal biomass and its recovery

Immobilized fungal biomass (Aspergillus niger and Aspergillus flavus) was prepared and analysed for the simultaneous removal of Cu(II) ion and Reactive Green 6 dye from aqueous phase. Different characterization analysis was utilized to exploit the adsorption characteristics of fungal biomass. Batch biosorption tests, performed to investigate the factors influencing biosorption process inferred optimal values of 25 mg/L of adsorbate with equilibrium time of 60 min, 2.5 g of immobilized fungal biomass, temperature of 303 K and pH of 5.0 for the maximal removal of pollutants. The obtained experimental data was utilized to evaluate the kinetic, thermodynamic and equilibrium models. Langmuir isotherm model has higher correlation coefficient [Cu(II) ion = 0.8625 and RG 6 dye = 0.8575] with small values of errors (RMSE = 3.746 and SSE = 56.12 for Cu(II) ion; RMSE = 4.872 and SSE = 11.87 for RG 6 dye). Kinetic studies performed to evaluate the adsorption rate mechanism of this present study indicated that pseudo-first order and pseudo-second order kinetics to be most fitting model for removal of Cu(II) ions and Reactive green dye respectively. Thermodynamic analysis inferred the spontaneous, random, and exothermic nature of the biosorption process based on ΔG^o, ΔH^o, and ΔS^o values respectively. The prepared biomass can be an alternative for the elimination of toxic pollutants from wastewater.

Current Trends on Role of Biological Treatment in Integrated Treatment Technologies of Textile Wastewater

Wastewater discharge is a matter of concern as it is the primary source of water pollution. Consequently, wastewater treatment plays a key role in reducing the negative impact that wastewater discharge produce into the environment. Particularly, the effluents produced by textile industry are composed of high concentration of hazardous compounds such as dyes, as well as having high levels of chemical and biological oxygen demand, suspended solids, variable pH, and high concentration of salt. Main efforts have been focused on the development of methods consuming less water or reusing it, and also on the development of dyes with a better fixation capacity. However, the problem of how to treat these harmful effluents is still pending. Different treatment technologies have been developed, such as coagulation-flocculation, adsorption, membrane filtration, reverse osmosis, advanced oxidation, and biological processes (activated sludge, anaerobic-aerobic treatment, and membrane bioreactor). Concerning to biological treatments, even though they are considered as the most environmentally friendly and economic methods, their industrial application is still uncertain. On the one hand, this is due to the costs of treatment plants installation and, on the other, to the fact that most of the studies are carried out with simulated or diluted effluents that do not represent what really happens in the industries. Integrated treatment technologies by combining the efficiency two or more methodologies used to be more efficient for the decontamination of textile wastewater, than treatments used separately. The elimination of hazardous compounds had been reported using combination of physical, chemical, and biological processes. On this way, as degradation products can sometimes be even more toxic than the parent compounds, effluent toxicity assessment is an essential feature in the development of these alternatives. This article provides a critical view on the state of art of biological treatment, the degree of advancement and the prospects for their application, also discussing the concept of integrated treatment and the importance of including toxicity assays to reach an integral approach to wastewater treatment.

Marine associated microbial consortium applied to RBBR textile dye detoxification and decolorization: Combined approach and metatranscriptomic analysis

The combination of different microorganisms and their metabolisms makes the use of microbial consortia in bioremediation processes a useful approach. In this sense, this study aimed at structuring and selecting a marine microbial consortium for Remazol Brilliant Blue R (RBBR) detoxification and decolorization. Experimental design was applied to improve the culture conditions, and metatranscriptomic analysis to understand the enzymatic pathways. A promising consortium composed of Mucor racemosus CBMAI 847, Marasmiellus sp. CBMAI 1062, Bacillus subtilis CBMAI 707, and Dietzia maris CBMAI 705 was selected. This consortium showed 52% of detoxification and 86% of decolorization in the validation assays after seven days of incubation in the presence of 500 ppm of RBBR. Reduction in RBBR color and toxicity were achieved by biosorption and microbial metabolisms. Metatranscriptomic data indicate that the consortium was able to decolorize and breakdown the RBBR molecule using a coordinated action of oxidases, oxygenases, and hydrolases. Epoxide hydrolases and glyoxalases expression could be associated with the decrease in toxicity. The efficiency of this marine microbial consortium suggests their use in bioremediation processes of textile effluents.

Crude Enzyme of Aspergillus sp. 3 Immobilized in Chitosan-Beads to Decolorize Batik Effluent

Batik is one of Indonesian’s cultures which has a unique symbolic meaning and has high aesthetic value for the Indonesian. The number of industries engaged in this business will bring new problems to the surrounding environment because batik effluent can pollute the river. This untreated dye effluent is very dangerous and can damage the environment because it is toxic, carcinogenic, and even mutagenic. One of the effluent treatment methods is by a biological method. The indigenous Aspergillus sp. 3 fungi are isolated from batik effluent, taken from the batik industry in Banyumas regency. The utilization of fungi for effluent treatment can be done by adsorption and enzymatic method. Degradation using enzymes is known to be more effective. Aspergillus fungi contain ligninolytic enzymes. Ligninolytic enzymes play an important role in degrading lignin on lignocellulosic substrates. This research is aimed to apply fungal enzyme immobilization for decolorization of batik effluent. Chitosan-based beads components are made with a combination of chitosan, STPP 2%, and phosphate buffer. Enzyme immobilization is done by immersing the chitosan solution in the Ligninolytic enzyme solution. Ligninolytic enzymes that are immobilized into chitosan will form beads that will be dissolved into batik effluent. The development of enzyme immobilization techniques is applied to batik effluent with a percentage of effluent decolorization until 96,8%. The best treatment results can reduce the value of Total Dissolved Solids (TDS) from 16,500 mg/L to 4005 mg/l and can also reduce the pH value of the effluent.

Synthetic dyes biodegradation by fungal ligninolytic enzymes: Process optimization, metabolites evaluation and toxicity assessment

This work aimed to provide information that contributes to establishing environmental-friendly methods for synthetic dyes' degradation. The potential decolorization capacity of the crude enzymatic extract produced by Phanerochaete chrysosporium CDBB 686 using corncob as a substrate was evaluated on seven different dyes. Critical variables affecting the in-vitro decolorization process were further evaluated and results were compared with an in-vivo decolorization system. Decolorization with enzymatic extracts presented advantages over the in-vivo system (higher or similar decolorization within a shorter period). Under improved in-vitro process conditions, the dyes with higher decolorization were: Congo red (41.84 %), Poly R-478 (56.86 %), Methyl green (69.79 %). Attempts were made to confirm the transformation of the dyes after the in-vitro process as well as to establish a molecular basis for interpreting changes in toxicity along with the degradation process. In-vitro degradation products of Methyl green presented a toxicity reduction compared with the original dye; however, increased toxicity was found for Congo red degradation products when compared with the original dyes. Thus, for future applications, it is crucial to evaluate the mechanisms of biodegradation of each target synthetic dye as well as the toxicity of the products obtained after enzymatic oxidation.

Decolorization and detoxification of triphenylmethane dyes by isolated endophytic fungus, Bjerkandera adusta SWUSI4 under non-nutritive conditions

Biodecolorization by microorganisms is a potential treatment technique because they seem to be environmentally safe. In the present study, the decolorization and detoxification of cotton blue, crystal violet, malachite green and methyl violet by endophytic fungi were investigated. Preliminary screening result indicated that SWUSI4, identified as Bjerkandera adusta, demonstrated the best decolorization for the four TPM dyes within 14 days. Furthermore, optimization result demonstrated the decolorization rate could reach above 90% at 24 h by live cells of isolate SWUSI4 when 4 g biomass was added into 100-mL dyes solution with the concentration 50 mg/L and shaking (150 rpm) conditions. Moreover, decolorization mechanism analysis shows that the decolorization was caused by the isolate SWUSI4 that mainly includes both absorption of biomass and/or degradation of enzymes. Biosorption of dyes was attributed to binding to hydroxyl, amino, phosphoryl alkane, and ester–lipids groups based on Fourier transform infrared (FTIR) analyses. The biodegradation potential of SWUSI4 was further suggested by the change of peaks in the ultraviolet–visible (UV–vis) spectra and detection of manganese peroxidase and lignin peroxidase activities. Finally, the phytotoxicity test confirmed that the toxicity of TPM dyes after treatment with SWUSI4 was significantly lower than that before treatment. These results indicate that an endophytic SWUSI4 could be used as a potential TPM dyes adsorption and degradation agent, thus facilitating the study of the plant–endophyte symbiosis in the bioremediation processes.

Myco-decontamination of azo dyes: nano-augmentation technologies

Effluents of textile, paper, and related industries contain significant amounts of synthetic dyes which has serious environmental and health implications. Remediation of dyes through physical and chemical techniques has specific limitations. Augmented biological decontamination strategies 'microbial remediation' may involve ring-opening of dye molecules besides the reduction of constituent metal ions. Both bacterial and fungal genera are known to exhibit metabolic versatility which can be harnessed for effective bio-removal of the toxic dye contaminants. Ascomycetous/basidiomycetes fungi can effectively decontaminate azo dyes through laccase/peroxidase enzyme-mediated catalysis. The extent, efficacy, and range of fungal dye decontamination can be enhanced by the conjugated application of nanomaterials, including nanoparticles (NPs) and their composites. Fungal cell-enabled NP synthesis- 'myco-farmed NPs', is a low-cost strategy for scaled-up fabrication of a variety of metal, metal oxide, non-metal oxide NPs through oxidation/reduction of dissolved ions/molecules by extracellular biomolecules. Augmented and rapid decontamination of azo dyes at high concentrations can be achieved by the use of myco-farmed NPs, NPs adsorbed fungal biomass, and nano-immobilized fungi-derived bio-catalytical agents. This manuscript will explore the opportunities and benefits of mycoremediation and application of fungus-NP bionanoconjugate to remediate dye pollutants in wastewaters and land contaminated with the effluent of textile industries.

Resuscitation, isolation and immobilization of bacterial species for efficient textile wastewater treatment: A critical review and update

Given highly complex and recalcitrant nature of synthetic dyes, textile wastewater poses a serious challenge on surrounding environments. Until now, biological treatment of textile wastewater using efficient bacterial species is still considered as an environmentally friendly and cost-effective approach. The advances in resuscitating viable but non-culturable (VBNC) bacteria via signaling compounds such as resuscitation-promoting factors (Rpfs) and quorum sensing (QS) autoinducers, provide a vast majority of potent microbial resources for biological wastewater treatment. So far, textile wastewater treatment from resuscitating and isolating VBNC state bacteria has not been critically reviewed. Thus, this review aims to provide a comprehensive picture of resuscitation, isolation and application of bacterial species with this new strategy, while the recent advances in synthetic dye decolorization were also elaborated together with the mechanisms involved. Discussion was further extended to immobilization methods to tackle its application. We concluded that the resuscitation of VBNC bacteria via signaling compounds, together with biochar-based immobilization technologies, may lead to an appealing biological treatment of textile wastewater. However, further development and optimization of the integrated process are still required for their wide applications.

Potential of residual fungal biomass: a review

In this study, it was evaluated and documented the potential uses of the residual fungal biomass from fermentation. The chemical composition of the biomass was determined by instrumental analysis techniques for its characterization and its possible application. It was found that this biomaterial is generally composed of sugars, proteins, and lipids, which provide it certain properties and applications that must be characterized morphologically, chemically, and mechanically. The residual fungal biomass could be used for two processes: the extraction of biopolymers, with several applications in the food industry, cosmetics, and pharmaceutical, among others; and the removal of contaminants by mechanisms of adsorption with biopolymers, known also as biosorption, in tertiary treatments of wastewater.

Nano-engineered Adsorbent for the Removal of Dyes from Water: A Review

Background:

The huge quantity of wastewater, containing poisonous and hazardous dyes, is released by various industries which pollute water in direct and indirect ways. Most of the dyes are a dangerous class of water contaminants which have affected the environment drastically. Some dyes such as congo red, rhodamine B, methylene blue, methyl violet, and crystal violet are a serious threat to human beings.

Remediation Method:

Numerous methods are available for the removal of dyes from water. Adsorption, being a superior and eco-friendly technique, has advantage of eliminating organic dyes because of the availability of materials as adsorbents. The inexpensive nanomaterials are a more attractive choice for remediation of various dyes due to their unique properties and offer an adequate pathway to adsorb any organic dye from water to overcome its hazardous effects on human health.

Results:

In this review, we have discussed the latest literature related to various types of synthesis, characterization and uses as adsorbent for highly adsorptive removal capacity of nanoparticles for organic dyes.

Conclusion:

Adsorption technology provides an attractive pathway for further research and improvement in more efficient nanoparticles, with higher adsorption capacity, for numerous dyes to eliminate the dyes discharged from various industries and thus reduce the contamination of water. Therefore, nanocomposites may contribute to future prospective water treatment process.

Lignolytic mushroom Lenzites elegans WDP2: Laccase production, characterization, and bioremediation of synthetic dyes

A mycoremedial study was undertaken for decolourization of synthetic dyes using wood rot fungal culture Lenzites elegans WDP2. The culture was isolated from decaying wood as fruiting body, and identified on the basis of 5.8S ITS rRNA gene sequence analysis. Qualitative plate screening of culture showed extracellular laccase and lignin peroxidase production, while only laccase enzyme was produced in higher amount (156.793 Uml^-1) in minimal salt broth medium containing glucose and veratryl alcohol. Laccase activity was increased up to 189.25 Uml^-1 after optimization of laccase production by optimization of one variable at a time approach. Molecular characterization of laccase enzyme was done using SDS PAGE and Native PAGE based isozyme analyses. The culture was able to decolorize three synthetic dying compounds (congo red, Malachite green and brilliant green) in broth media, while showed very less decolourization in plate assay. The fungal culture varied in their dye decolourizing potential in broth culture, showing 92.77%, 21.27% and 98.8% maximum decolourization of brilliant green, malachite green and congo red respectively. The congo red dye was completely bio-absorbed by fungal culture within one month. The fungal decolourized broth also revealed the extracellular laccase activity; varied from 10 Uml^-1 to 68.5 Uml^-1 in all the three cases, supports the involvement of laccase enzyme in decolorization. Phase contrast microscopy clearly revealed bio-sorption of the dyes by fungal culture into the mycelium/spores in the photomicrographs.