Integrated fungal biomass and activated sludge treatment for textile wastewaters bioremediation

Self-doped N, S porous carbon from semi-coking wastewater-based phenolic resin for supercapacitor electrodes

Contamination of phenolic compounds has devastating effects on the environment. Therefore, its harmless treatment and recycling have received extensive attention. Herein, a novel method for preparing N-S doped phenolic resin (NSPR) from phenols, N and S groups in semi-coking wastewater, and formaldehyde are developed. The KOH is consequently incorporated into the NSPR through simultaneous carbonization and activation in a single step to produce porous carbon material (NSPC). The as-obtained NSPC exhibits a high specific capacitance of 182 F g^-1 at 0.5 A g^-1, a high energy density of 9.1 Wh kg^-1 at a power density of 0.15 kW kg^-1, and remarkable cycling stability in aqueous KOH electrolyte. This outstanding electrochemical performance is attributed to its ultrahigh specific surface area (SSA, 2,523 m² g^-1), enormous total pore volume (V_t, 1.30 cm³ g^-1), rational pore structure, and N-S heteroatom self-doping (0.76 at% N and 0.914 at% S), which ensures adequate charge storage, rapid electrolyte ion diffusion, and contributed pseudo-capacitance. This work not only provides a facile method for transforming phenolic wastewater into high-value products but also offers a cost-effective and high-performance porous carbon material for supercapacitors.

Diversity and Metabolic Activity of Fungi Causing Biodeterioration of Canvas Paintings

Research into the biodeteriorative potential of fungi can serve as an indicator of the condition of heritage items. Biodeterioration of canvas paintings as a result of fungal metabolic activity is understudied with respect to both the species diversity and mechanisms involved. This study brings new evidence for the physiology of fungi biodeteriorative capacity of canvas paintings. Twenty-one fungal isolates were recovered from four oil paintings (The Art Museum, Cluj-Napoca) and one gouache painting (private collection), dating from the 18th to 20th centuries. The species, identified based on the molecular markers Internal Transcribed Spacer (ITS), beta-tubulin (tub2), or translation elongation factor 1 (TEF-1), are common colonisers of canvas paintings or indoor environments (e.g., Penicillium spp., Aspergillus spp., Alternaria spp.). Fungi enzymatic profiles were investigated by means of hydrolysable substrates, included in culture media or in test strips, containing components commonly used in canvas paintings. The pigment solubilisation capacity was assessed in culture media for the primary pigments and studied in relation to the organic acid secretion. Caseinases, amylases, gelatinases, acid phosphatase, N-acetyl-β-glucosaminidase, naphthol-AS-BI-phosphohydrolase, and β-glucosidase were found to be the enzymes most likely involved in the processes of substrate colonisation and breakdown of its components. Aureobasidium genus was found to hold the strongest biodeteriorative potential, followed by Cladosporium, Penicillium, Trichoderma, and Aspergillus. Blue pigment solubilisation was detected, occurring as a result of organic acids secretion. Distinct clusters were delineated considering the metabolic activities detected, indicating that fungi specialise in utilisation of certain types of substrates. It was found that both aged and modern artworks are at risk of fungal biodeterioration, due to the enzymatic activities’ diversity and intensity, pigment solubilisation capacity or pigment secretion.

Succession of diversity, functions, and interactions of the fungal community in activated sludge under aromatic hydrocarbon stress

Although fungi are regarded as the important degraders of aromatic hydrocarbons (AHs) in various environments, the dynamic succession and interaction of their community under aromatic hydrocarbon stress has been rarely reported. In this study, we systematically investigated the responses of the fungal community and the associations among fungal species when facing the continuous stress of two typical AHs, benzene and naphthalene. Using high-throughput sequencing technology, we demonstrated that fungal diversity displayed a significant downward trend during six weeks of continuous aromatic hydrocarbon treatment. Community succession was observed during the operational period, and the relative abundance of some typical degraders, such as Exophiala sp. and Candida sp., increased during the later period of operation. Meanwhile, by predicting the functions of the fungal community through PICRUSt2, we found that some relevant enzymes, such as peroxidase, dioxygenase, and monooxygenase, may play an important role in the degradation process and maintaining overall community multifunctionality. Furthermore, the measurement of modified normalized stochasticity ratio (MST) indicated that continuous aromatic hydrocarbon stress resulted in a stronger deterministic process in community assembly over time, suggesting environmental selection dominated succession of the fungal community in activated sludge. Finally, molecular ecological network analysis (MENA) demonstrated that, the cooperative behaviors among members, the network keystone genera related to biodegradation, such as Exophiala sp. and Haglerozyma sp., and a well-organized topological structure, together, maintained the structural stability of the fungal community under AH stress. Our study provides new insights for understanding the stability of fungal communities during the degradation of contaminants in activated sludge.

Multifunctional Membranes-A Versatile Approach for Emerging Pollutants Removal

This paper presents a comprehensive literature review surveying the most important polymer materials used for electrospinning processes and applied as membranes for the removal of emerging pollutants. Two types of processes integrate these membrane types: separation processes, where electrospun polymers act as a support for thin film composites (TFC), and adsorption as single or coupled processes (photo-catalysis, advanced oxidation, electrochemical), where a functionalization step is essential for the electrospun polymer to improve its properties. Emerging pollutants (EPs) released in the environment can be efficiently removed from water systems using electrospun membranes. The relevant results regarding removal efficiency, adsorption capacity, and the size and porosity of the membranes and fibers used for different EPs are described in detail.

Engineering globins for efficient biodegradation of malachite green: two case studies of myoglobin and neuroglobin

Engineered globins such as H64D Mb and A15C/H64D Ngb were efficient in the degradation of malachite green, with activities much higher than those of some native enzymes.

Talaromyces cellulolyticus as a promising candidate for biofilm construction and treatment of textile wastewater

Screening of microorganisms with broad-spectrum adaptability to extreme acid-base conditions and highperformance is essential for the construction of high-efficient biochemical wastewater treatment system. Herein, an acid-tolerant fungus isolated from acid medium was successfully identified through micromorphological observation and molecular characterization. The isolated fungus matched well with the filamentous fungus and was eventually identified as Talaromyces cellulolyticus. Considering the wide-range adaptability to pH condition (2.0-9.0), high cellulase activity (11.25 U mL^-1), ideal biofilm-forming property (17.87 mg cm^-3) on the surface of ceramsites, high tolerance to metal ions, and potential adsorption performance for aniline dyes, T. cellulolyticus issuitable for the construction of biofilm treatment system and treatment of textile wastewater based on the investigation of the removal efficiency of chemical oxygen demand and chromaticity of the synthetic textile wastewater. A promising candidate filamentous fungus for the treatment of textile wastewater was provided.

Treatment of NSAPs-rich petrochemical wastewaters using a two-stage combined process of fungi and activated sludge

A two-stage biological process using fungi and bacteria was set-up and tested for treating a petrochemical wastewater containing naphthalene sulphonic acid polymers. The fungal treatment was carried out through a trickling filter inoculated with Pleurotus ostreatus attached on Luffa cylindrica acting as both physical support and carbon source. The fungal reactor was operated in non-sterile conditions setting two pH values (5 and 6) and two hydraulic retention times (2 d and 3 d). The effluent was then sent to an activated sludge reactor operating the second stage of the treatment. Using an HPLC-based technique, it was observed that the fungal reactor was capable of reducing the polymerization grade of naphthalene sulphonic acid polymers up to 35%, thus increasing significantly the biodegradability of the petrochemical wastewater, from the initial 9% to 46%. The two-stage process allowed to remove about 50% of the total COD much higher than 9% that can be achieved with activated sludge alone. The use of Luffa cylindrica as support for fungi allowed to limit bacterial contamination of the trickling filter and enhanced enzymatic production (on average 20 U/L of Laccase) without any release of non-biodegradable by-products in the effluent. Extraction and PCR-amplification of fungal DNA was carried out along with over 70 d running process in order to monitor the changes of the fungal community inside the reactors. Results showed that Meyerozyma, Fusarium and Thricoderma, spp. developed inside the reactor with Thricoderma, spp. representing the main constituent of fungal biomass at the end of the experiment.

Bioaugmentation with immobilized endophytic Penicillium restrictum to improve quorum quenching activity for biofouling control in an aerobic hollow-fiber membrane bioreactor treating antibiotic-containing wastewater

The effects of bioaugmentation with immobilized Penicillium restrictum on the removal efficiency of sulfamethoxazole (SMX), erythromycin (ERY) and tetracycline (TC) antibiotics as well as membrane biofouling was studied using hollow-fiber membrane bioreactor (HF-MBR). Bioaugmentation with P. restrictum led to a significant change in the antibiotic removal efficiency and relative abundance of aerobic microbial community, most probably as a result of its quorum quenching activity. Furthermore, in addition to its role in the increase of SMX and ERY removal efficiencies and the decrease of their sorption on solid phase, bioaugmentation significantly reduced the transmembrane pressure which in turn reduced membrane clogging. The most abundant phyla in sludge and biofilm samples in the presence of P. restrictum were observed to be Proteobacteria, Bacteroidetes and Firmicutes. Differences in bacterial compositions and their specificity in biodegradation of antibiotics in different reactors showed that bacteria were specifically selected under the pressure of antibiotics and growing fungus.

Possibility to Biotransform Anthracyclines by Peroxidases Produced by Bjerkandera adusta CCBAS 930 with Reduction of Geno- and Cytotoxicity and Pro-Oxidative Activity

The aim of this study was to evaluate the bioremoval mechanism of anthracycline antibiotics by the white-rot fungus B. adusta CCBAS 930. The activity of oxidoreductases and levels of phenolic compounds and free radicals were determined during the biotransformation of anthraquinone antibiotics: daunomycin (DNR) and doxorubicin (DOX) by B. adusta strain CCBAS 930. Moreover, phytotoxicity (Lepidium sativum L.), ecotoxicity (Vibrio fischeri), genotoxicity and cytotoxicity of anthraquinone dyes were evaluated before and after biological treatment. More than 80% and 90% of DNR and DOX were removed by biodegradation (decolorization). Initial solutions of DNR and DOX were characterized by eco-, phyto-, geno- and cytotoxicity. Despite efficient decolorization, secondary metabolites, toxic to bacteria, formed during biotransformation of anthracycline antibiotics in B. adusta CCBAS 930 cultures. DNR and DOX metabolites did not increase reactive oxygen species (ROS) production in human fibroblasts and resazurin reduction. DNR metabolites did not change caspase-3 activity.

The role of cosubstrate and mixing on fungal biofilm efficiency in the removal of tannins

Tannins are polyphenolic compounds produced by plants and they are used in industrial vegetable tanning of leather. Tannins represent one of the low biodegradability substances in tannery wastewaters with high recalcitrant soluble chemical oxygen demand, furthermore high concentration of tannins can inhibit biological treatment. In the present study, four novel rotating submerged packed bed reactors were inoculated with a selected fungal strain to reach a biological degradation of tannins in non-sterile conditions. The selected fungal strain, Aspergillus tubingensis MUT 990, was immobilised in polyurethane foam cubes carriers and inserted inside a submerged rotating cage reactors. The reactors were feed with a solution composed of four tannins: Quebracho (Schinopsis spp.), Wattle (Mimosa spp.), Chestnut (Castanea spp.) and Tara (Caesalpinia spp.). Four reactors with a volume of 4 L each were used, the co-substrate was pure malt extract, the hydraulic retention time was 24 h and the pH setpoint was 5.5. The reactors configuration was chosen to allow the study of the effect of rotation and the co-substrate addition on tannins removal. The experiment lasted two months and it was achieved 80% of chemical oxygen demand and up to 90% dissolved organic carbon removal, furthermore it was detected an important tannase activity.

Performance of a Newly Isolated Salt-Tolerant Yeast Strain Sterigmatomyces halophilus SSA-1575 for Azo Dye Decolorization and Detoxification

The effective degradation of hazardous contaminants remains an intractable challenge in wastewater processing, especially for the high concentration of salty azo dye wastewater. However, some unique yeast symbionts identified from the termite gut system present an impressive function to deconstruct some aromatic compounds, which imply that they may be valued to work on the dye degradation for various textile effluents. In this investigation, a newly isolated and unique yeast strain, Sterigmatomyces halophilus SSA-1575, was identified from the gut system of a wood-feeding termite (WFT), Reticulitermes chinensis. Under the optimized ambient conditions, the yeast strain SSA-1575 showed a complete decolorization efficiency on Reactive Black 5 (RB5) within 24 h, where this azo dye solution had a concentration of a 50 mg/L RB5. NADH-dichlorophenol indophenol (NADH-DCIP) reductase and lignin peroxidase (LiP) were determined as the key reductase and oxidase of S. halophilus SSA-1575. Enhanced decolorization was recorded when the medium was supplemented with carbon and energy sources, including glucose, ammonium sulfate, and yeast extract. To understand a possible degradation pathway well, UV-Vis spectroscopy, FTIR and Mass Spectrometry analyses were employed to analyze the possible decolorization pathway by SSA-1575. Determination of relatively high NADH-DCIP reductase suggested that the asymmetric cleavage of RB5 azo bond was mainly catalyzed by NADH-DCIP reductase, and finally resulting in the formation of colorless aromatic amines devoid of any chromophores. The ecotoxicology assessment of RB5 after a decolorization processing by SSA-1575, was finally conducted to evaluate the safety of its metabolic intermediates from RB5. The results of Microtox assay indicate a capability of S. halophilus SSA-1575, in the detoxification of the toxic RB5 pollutant. This study revealed the effectiveness of halotolerant yeasts in the eco-friendly remediation of hazardous pollutants and dye wastewater processing for the textile industry.

Role of bacterivorous organisms on fungal-based systems for natural tannin degradation

Tannery wastewater presents high concentrations of organic load and pollutant recalcitrant molecules (e.g. tannins), which reduce the efficiency of biological treatment processes. Recent studies showed that several fungal species and strains are effective in the degradation of tannins. However, high bacterial load can negatively affect fungal growth, reducing system stability and degradation performances.

The aim of the present study was to evaluate the effects of the introduction of bacterivorous grazers (ciliates and/or rotifers) in batch scale experiments using fungi to remove Tara tannin, i.e. to check the potential synergistic effect between fungi and bacterivorous grazers in the degradation of recalcitrant compounds. In this context, the ciliated grazers Paramecium calkinsi, Tetrahymena sp., Pseudovorticella sp., and the rotifer Lecane inermis, preliminary selected according to their ability to grow in a solution prepared with Tara tannin, were separately tested. Activated sludge, including a complex mixture of native grazers, was used as experimental control. The following parameters were monitored: bacterial load, number of grazers/mL and Soluble Chemical Oxygen Demand (SCOD). Colony Forming Unit (CFU)/grazers ratio was also calculated. Particular attention was paid to: i) bacterial load reduction and ii) enhancement of recalcitrant compounds degradation, and we observed that in all experimental conditions where grazers occurred bacterial load was significantly reduced and the system achieved a higher SCOD removal in a shorter time. Our findings provide useful insights for the stabilization of fungal-based systems in non-sterile conditions.

Stability of fungal biomass continuously fed with tannic acid in a non-sterile moving-packed bed reactor

A number of bacteria and fungi are known to degrade tannins. In this study, the efficiency of the white-rot fungus, Bjerkandera adusta MUT 2295, was evaluated for the treatment of a synthetic solution prepared with tannic acid. Tests were performed in continuously fed, bench-scale, packed-bed reactors, operated under non-sterile conditions with biomass immobilized within PolyUrethane Foam cubes (PUFs). The main parameters monitored to evaluate the process efficiency were: soluble Chemical Oxygen Demand (sCOD), Total Organic Carbon (TOC) removal, and activities. of Tannase and Lignin Peroxidase. At the end of the process, additional parameters were evaluated, including the increase of fungal dry weight and the presence of ergosterol. The reactor was operative for 210 days, with maximum sCOD and TOC removal of 81% and 73%, respectively. The reduction of sCOD and TOC were positively correlated with the detection of Tannase and Lignin Peroxidase (LiP) activities. Increases in biomass within the PUF cubes was associated with increases in ergosterol concentrations. This study proved that the fungal-based system tested was efficient for the degradation of tannic acid over a period of time, and under non-sterile conditions.

Determination of the effect of RBBR on laccase activity and gene expression level of fungi in lichen structure

This study provides information about the differential transcription regulation of laccase genes in response to RBBR dye. To this purpose, we determined the laccase gene expression, laccase activity, and protein profile of lichen-forming fungi supported to RBBR dye. For those obtained from optimal laccase genes expression profiles, we modified different RNA extraction protocols to obtain high quality and quantity RNA to be used in downstream applications in lichen-forming fungus. We also determined the expression of ten laccase genes in response to RBBR dye by qRT-PCR and validated protein profile. As a result of our study, a high laccase activity of 522 U mL^-1 was obtained after submerged fermentation for 17 days. The maximal laccase activity to RBBR dye was obtained at 408 h. The expression profiles of laccase gene expression on ten laccase genes showed up- or down-regulation in course of eight fermentation times. The most up-regulated gene during the process was lac8. However, poxa1b gene expression was lowest in lichen-forming fungi biomass supplemented with RBBR dye. This study has revealed the influence of RBBR dye on laccase activity levels and the determination of gene expression levels in lichen-forming fungi.

Removal of Quebracho and Tara tannins in fungal bioreactors: Performance and biofilm stability analysis

Tannins are polyphenolic compounds produced by plants that are used in the vegetable tanning of leather at industrial scale. Quebracho tannin and Tara tannin are intensively used by the tanning industry and are two of the most recalcitrant compounds that can be found in tannery wastewaters. In this study two reactors fed with Quebracho tannin and Tara tannin, respectively, were inoculated with polyurethane foam cubes colonized with a fungal strain biofilm of Aspergillus tubingensis MUT 990. A stable biofilm was maintained in the reactor fed with Quebracho tannin during 180 days of operation. Instead, biofilm got detached from the foam cubes during the start-up of the reactor fed with Tara tannin and a bacterial-based suspended culture was developed and preserved along the operational period (226 days). Soluble chemical oxygen demand removals up to 53% and 90% and maximum elimination capacities of 9.1 g sCOD m^-3 h^-1 and 37.9 g sCOD m^-3 h^-1 of Quebracho and Tara tannins, respectively, were achieved in the reactors without the addition of co-substrates. Next generation sequencing analysis for bacteria and fungi showed that a fungal consortium was developed in the reactor fed with Quebracho tannin while fungi were outcompeted by bacteria in the reactor fed with Tara tannin. Furthermore, Quebracho and Tara tannins were successfully co-treated in a single reactor where both fungi and bacteria were preserved.

Bioremediation of Landfill Leachate with Fungi: Autochthonous vs. Allochthonous Strains

Autochthonous fungi from contaminated wastewater are potential successful agents bioremediation thanks to their adaptation to pollutant toxicity and to competition with other microorganisms present in wastewater treatment plant. Biological treatment by means of selected fungal strains could be a potential tool to integrate the leachate depuration process, thanks to their fungal extracellular enzymes with non-selective catalytical activity. In the present work, the treatability of two real samples (a crude landfill leachate and the effluent coming from a traditional wastewater treatment plant) was investigated in decolorization experiments with fungal biomasses. Five autochthonous fungi, Penicillium brevicompactum MUT 793, Pseudallescheria boydii MUT 721, P. boydii MUT 1269, Phanerochaete sanguinea MUT 1284, and Flammulina velutipes MUT 1275, were selected in a previous miniaturized decolorization screening. Their effectiveness in terms of decolorization, enzymatic activity (laccases and peroxidases), biomass growth and ecotoxicity removal was compared with that of five allochthonous fungal strains, Pleurotus ostreatus MUT 2976, Porostereum spadiceum MUT 1585, Trametespubescens MUT 2400, Bjerkanderaadusta MUT 3060 and B. adusta MUT 2295, selected for their well known capability to degrade recalcitrant pollutants. Moreover, the effect of biomass immobilization on polyurethane foam (PUF) cube was assessed. The best decolorization (60%) was achieved by P. spadiceum MUT 1585, P. boydii MUT 721 and MUT 1269. In the first case, the DP was achieved gradually, suggesting a biodegradation process with the involvement of peroxidases. On the contrary, the two autochthonous fungi seem to bioremediate the effluent mainly by biosorption, with the abatement of the toxicity (up to 100%). The biomass immobilization enhanced enzymatic activity, but not the DP. Moreover, it limited the biomass growth for the fast growing fungi, MUT 721 and MUT 1269. In conclusion, robust and versatile strains coming from well-characterized collections of microorganisms can obtain excellent results comparing and even exceeding the bioremediation yields of strains already adapted to pollutants.

The divergence between fungal and bacterial communities in seasonal and spatial variations of wastewater treatment plants

In this study, quantitative PCR (qPCR) and high-throughput sequencing were used to simultaneously examine both bacteria and fungi across temporal and spatial scales in activated sludge from wastewater treatment plants (WWTPs). The ratio of fungi to bacteria was 0.43% on average after accounting for the multicopies in 16S rRNA gene (54.63%), indicating the number of fungi was far lower than bacteria in active sludge. The Miseq sequencing results revealed obvious seasonal and spatial variations in bacterial and fungal distribution patterns in WWTPs. Compared to bacteria, fungi showed a lower divergence in alpha and beta diversity, and exhibited less taxonomic diversity in both abundant and rare subcommunities at the class level, suggesting that the fungal community was less variable in this artificial ecosystem. Such variation of microbial communities was significantly correlated with geographical distance, DO, temperature, HRT, SRT, COD, TN and TP. In activated sludge, the main function of bacteria was chemoheterotrophy, fermentation, and nitrogen cycling processes, while the dominant functional guilds of fungi were saprotroph, animal pathogen, and animal endosymbiont. Moreover, both bacteria and fungi could play important roles in the degradation of toxicants, like hydrocarbon and aromatic compounds.

Tannery mixed liquors from an ecotoxicological and mycological point of view: Risks vs potential biodegradation application

Fungi are known to be present in the activated sludge of wastewater treatment plants (WWTP). Their study should be at the base of an overall vision of the plant effectiveness and of effluents sanitary impact. Moreover, it could be fundamental for the implementation of successful bioaugmentation strategies aimed at the removal of recalcitrant or toxic compounds. This is one of the first studies on the cultivable autochthonous mycoflora present in the mixed liquors of two WWTP treating either vegetable or chromium tannery effluents. All samples showed a risk associated with potential pathogens or toxigenic species and high ecotoxicity (Lepidium sativum and Raphidocelis subcapitata were the most sensitive organisms). Diverse fungal populations developed, depending on the origin of the samples (63% of the 102 identified taxa were sample-specific). The use of a fungistatic was determinant for the isolation and, thus, for the identification of sample-specific species with a lower growth rate. The incubation temperature also affected the mycoflora composition, even though at lower extent. A selective medium, consisting of agarised wastewater, allowed isolating fungi with a biodegradation potential. Pseudallescheria boydii/Scedosporium apiospermum species complex was ubiquitously dominant, indicating a possible role in the degradation of pollutants in both WWTP. Other species, i.e. Trichoderma spp., Trematosphaeria grisea, Geotrichum candidum, Lichtheimia corymbifera, Acremonium furcatum, Penicillium simplicissimum, Penicillium dangeardii, Fusarium solani, Scopulariopsis brevicaulis potentially could be involved in the degradation of specific pollutants of vegetable or chromium tannery wastewaters. However, several of these fungi are potential pathogens and their application, for an in situ treatment, must be carefully evaluated.

Removal of pharmaceutical compounds in water and wastewater using fungal oxidoreductase enzymes

Due to recalcitrance of some pharmaceutically active compounds (PhACs), conventional wastewater treatment is not able to remove them effectively. Therefore, their occurrence in surface water and potential environmental impact has raised serious global concern. Biological transformation of these contaminants using white-rot fungi (WRF) and their oxidoreductase enzymes has been proposed as a low cost and environmentally friendly solution for water treatment. The removal performance of PhACs by a fungal culture is dependent on several factors, such as fungal species, the secreted enzymes, molecular structure of target compounds, culture medium composition, etc. In recent 20 years, numerous researchers tried to elucidate the removal mechanisms and the effects of important operational parameters such as temperature and pH on the enzymatic treatment of PhACs. This review summarizes and analyzes the studies performed on PhACs removal from spiked pure water and real wastewaters using oxidoreductase enzymes and the data related to degradation efficiencies of the most studied compounds. The review also offers an insight into enzymes immobilization, fungal reactors, mediators, degradation mechanisms and transformation products (TPs) of PhACs. In brief, higher hydrophobicity and having electron-donating groups, such as amine and hydroxyl in molecular structure leads to more effective degradation of PhACs by fungal cultures. For recalcitrant compounds, using redox mediators, such as syringaldehyde increases the degradation efficiency, however they may cause toxicity in the effluent and deactivate the enzyme. Immobilization of enzymes on supports can enhance the performance of enzyme in terms of reusability and stability. However, the immobilization strategy should be carefully selected to reduce the cost and enable regeneration. Still, further studies are needed to elucidate the mechanisms involved in enzymatic degradation and the toxicity levels of TPs and also to optimize the whole treatment strategy to have economical and technical competitiveness.

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

Different technologies may be used for decolorization of wastewater containing dyes. Among them, biological processes are the most promising because they seem to be environmentally safe. The aim of this study was to determine the efficiency of decolorization of two dyes belonging to different classes (azo and triphenylmethane dyes) by immobilized biomass of strains of fungi (Pleurotus ostreatus – BWPH, Gleophyllum odoratum – DCa and Polyporus picipes – RWP17). Different solid supports were tested for biomass immobilization. The best growth of fungal strains was observed on the washer, brush, grid and sawdust supports. Based on the results of dye adsorption, the brush and the washer were selected for further study. These solid supports adsorbed dyes at a negligible level, while the sawdust adsorbed 82.5% of brilliant green and 19.1% of Evans blue. Immobilization of biomass improved dye removal. Almost complete decolorization of diazo dye Evans blue was reached after 24 h in samples of all strains immobilized on the washer. The process was slower when the brush was used for biomass immobilization. Comparable results were reached for brilliant green in samples with biomass of strains BWPH and RWP17. High decolorization effectiveness was reached in samples with dead fungal biomass. Intensive removal of the dyes by biomass immobilized on the washer corresponded to a significant decrease in phytotoxicity and a slight decrease in zootoxicity of the dye solutions. The best decolorization results as well as reduction in toxicity were observed for the strain P. picipes (RWP17).

Influence of ozonation and biodegradation on toxicity of industrial textile wastewater

The textile industry demands huge volumes of high quality water which converts into wastewater contaminated by wide spectrum of chemicals. Estimation of textile wastewater influence on the aquatic systems is a very important issue. Therefore, closing of the water cycle within the factories is a promising method of decreasing its environmental impact as well as operational costs. Taking both reasons into account, the aim of this work was to establish the acute toxicity of the textile wastewater before and after separate chemical, biological as well as combined chemical-biological treatment. For the first time the effects of three different combinations of chemical and biological methods were investigated. The acute toxicity analysis were evaluated using the Microtox^® toxicity test. Ozonation in two reactors of working volume 1 dm³ (stirred cell) and 20 dm³ (bubble column) were tested as chemical process, while biodegradation was conducted in two, different systems - Sequence Batch Reactors (SBR; working volume 1.5 dm³) and Horizontal Continuous Flow Bioreactor (HCFB; working volume 12 dm³). The untreated wastewater had the highest toxicity (EC50 value in range: 3-6%). Ozonation caused lower reduction of the toxicity than biodegradation. In the system with SBR the best results were obtained for the biodegradation followed by the ozonation and additional biodegradation - 96% of the toxicity removal. In the second system (with HCFB) two-stage treatment (biodegradation followed by the ozonation) led to the highest toxicity reduction (98%).

Performance of a newly isolated salt-tolerant yeast strain Pichia occidentalis G1 for degrading and detoxifying azo dyes

A salt-tolerant yeast named G1 which could decolorize various azo dyes was recently isolated and identified as Pichia occidentalis. Systematic researches on characterization, degradation pathway, detoxification effects and enzymes analysis of this yeast were done. The results showed that the optimal metabolism and growth parameters for strain G1 were: 2.0gL^-1 glucose, 0.6gL^-1 ammonium sulfate, 0.08gL^-1 yeast extract, 30gL^-1 NaCl, 160rmin^-1, 30°C and pH 5.0. More than 98% of 50mgL^-1 Acid Red B (ARB) could be decolorized within 16h under the optimal conditions. Additionally, strain G1 degraded and obviously detoxified ARB through a possible pathway successively consisting of decolorization, deamination/desulfonation and TCA cycle processes. Moreover, NADH-DCIP reductase was estimated as the key reductase for decolorization and ligninases including lignin peroxidase, manganese peroxidase and laccase were important oxidoreductases for further degradation of decolorization intermediates.

Study of the effect of the bacterial and fungal communities present in real wastewater effluents on the performance of fungal treatments

The use of the ligninolytic fungi Trametes versicolor for the degradation of micropollutants has been widely studied. However, few studies have addressed the treatment of real wastewater containing pharmaceutically active compounds (PhAC) under non-sterile conditions. The main drawback of performing such treatments is the difficulty for the inoculated fungus to successfully compete with the other microorganisms growing in the bioreactor. In the present study, several fungal treatments were performed under non-sterile conditions in continuous operational mode with two types of real wastewater effluent, namely, a reverse osmosis concentrate (ROC) from a wastewater treatment plant and a veterinary hospital wastewater (VHW). In all cases, the setup consisted of two parallel reactors: one inoculated with T. versicolor and one non-inoculated, which was used as the control. The main objective of this work was to correlate the operational conditions and traditional monitoring parameters, such as laccase activity, with PhAC removal and the composition of the microbial communities developed inside the bioreactors. For that purpose a variety of biochemical and molecular biology analyses were performed: phospholipid fatty acids analysis (PLFA), quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) followed by sequencing. The results show that many indigenous fungi (and not only bacteria, which were the focus of the majority of previously published research) can successfully compete with the inoculated fungi (i.e., Trichoderma asperellum overtook T. versicolor in the ROC treatment). We also showed that the wastewater origin and the operational conditions had a stronger impact on the diversity of microbial communities developed in the bioreactors than the inoculation or not with T. versicolor.

Biodegradation of phenolic compounds by Basidiomycota and its phenol oxidases: A review

The phylum Basidiomycota include organisms with enormous bioremediation potential. A variety of processes were proposed at the lab scale for using these fungi and their phenol oxidases in the degradation of phenolics. Here we present a survey of this topic using literature published mostly over the last 10 years. First, the sources of the enzymes are summarized. The laccase and tyrosinase were mainly from Trametes versicolor and Agaricus bisporus, respectively. Recently, however, new promising wild-type producers of the enzymes have emerged and a number of recombinant strains were also constructed, based mainly on yeasts or Aspergillus strains as hosts. The next part of the study summarizes the enzyme and whole-cell applications for the degradation of phenols, polyphenols, cresols, alkylphenols, naphthols, bisphenols and halogenated (bis)phenols in model mixtures or real wastewaters from the food, paper and coal industries, or municipal and hospital sewage. The enzymes were applied as free (crude or purified) enzymes or as enzymes immobilized in various supports or CLEAs, and optionally recycled or used in continuous mode. Alternatively, growing cultures or harvested mycelia were used instead. The products, which were characterized as quinones and their polymers in some cases, could be eliminated by filtration, flocculation or adsorption onto chitosan. The purity of a treated wastewater was monitored using a sensitive aquatic organism. It is concluded that low-cost sources of these enzymes should be searched for and the benefits of enzymatic, biological and physico-chemical methods could be combined to make the processes fit for industrial use.

Evaluation of an eventual ecotoxicity induced by textile effluents using a battery of biotests

Textile industry is considered as one of the important factors of the economic growth in Tunisia. However, this prominent role has certainly some drawbacks mainly represented by the huge amounts of textile wastewaters generated that become a real menace to nature. Many previous studies showed the purifying potential of some activated sludge and bacteria (Pseudomonas putida) to decolourize textile effluents. However, in many cases, decolourization of wastewaters is not necessary associated with detoxification, generating a real risk for the ecosystem in general. We evaluated in this work the induced toxicity of a textile effluent before and after its treatment with activated sludge followed by P. putida, using a battery of biotests. This study proved the detoxifying power of the activated sludge according to most of ecotoxicity tests. The treatment with P. putida did not improve the quality of the effluent; on the contrary, it could increase its toxicity. Daphnia magna and Raphidocelis subcapitata appear to be the most sensitive organisms in assessing eventual toxicity caused by this kind of wastewaters.

Treatment of heavy oil wastewater by UASB-BAFs using the combination of yeast and bacteria

A novel system integrating an upflow anaerobic sludge blanket (UASB) reactor and a two-stage biological aerated filter (BAF) system was investigated as advanced treatment of heavy oil wastewater with large amounts of dissolved recalcitrant organic substances and low levels of nitrogen and phosphorus nutrients. #1 BAF, inoculated with two yeast strains (Candida tropicalis and Rhodotorula dairenensis), was installed in the upper reaches of #2 BAF inoculated with activated sludge. During the 180-day study period, the chemical oxygen demand (COD), ammonia nitrogen (NH3-N), oil and polyaromatic hydrocarbons (PAHs) in the wastewater were removed by 90.2%, 90.8%, 86.5% and 89.4%, respectively. Although the wastewater qualities fluctuated and the hydraulic retention time continuously decreased, the effluent quality index met the national discharge standard steadily. The UASB process greatly improved the biodegradability of the wastewater, while #1 BAF played an important role not only in degrading COD but also in removing oil and high molecular weight PAHs. This work demonstrates that the hybrid UASB-BAFs system containing yeast-bacteria consortium has the potential to be used in bioremediation of high-strength oily wastewater.

Decolouration of industrial metal-complex dyes in successive batches by active cultures of Trametes pubescens

The decolouration of the metal-complex dyes Bemaplex Navy M-T (150 mg/L) and Bezaktiv Blue BA (150 mg/L) in nine successive batches by immobilised cultures of the white-rot fungus Trametes pubescens was studied. Two different types of immobilisation supports were used: the commercial carriers Kaldnes™ K1 (synthetic supports) and sunflower-seed shells (SS) (natural supports). Bemaplex showed more resistance to degradation by T. pubescens cultures than Bezaktiv, especially in the K1 cultures. Thus, SS cultures led to decolouration percentages higher than 59% for Bemaplex in all the batches save for the last two and higher than 50% for Bezaktiv in all the batches except for the 2nd and 9th ones. K1 cultures showed decolouration percentages for Bemaplex higher than 42% in batches 1, 3, 4, 5 and 7 and for Bezaktiv higher than 70% in all the batches save for the last one. Dye decolouration was mainly due to enzyme action (biodegradation).

Degradation of azo dye acid orange 7 in a membrane bioreactor by pellets and attached growth of Coriolus versicolour

The aim of this study was to systematically compare the degradation of azo dye acid orange 7 by spongy pellets and attached biofilm of Coriolus versicolour (NBRC 9791) in a membrane bioreactor (MBR) under non-sterile conditions. Mild stirring (35 rpm) resulted in spherical (φ=0.5 cm), spongy pellets and concomitantly triggered high enzymatic activity of the fungus, allowing for excellent decolouration (>99%) of a synthetic wastewater containing the dye. However, bacterial contamination eventually damaged the fungus pellets, leading to decreased decolouration efficiency. Promotion of attached growth on a plastic support along with formation of spherical spongy pellets allowed maintenance of high enzymatic activity and decolouration/degradation for an extended period. Hydraulic retention time (HRT) could influence the level of enzymatic activity and decolouration; however, even at the shortest HRT (1 day) examined, the MBR could accomplish >95% decolouration.

Biotreatment of textile effluent in static bioreactor by Curvularia lunata URM 6179 and Phanerochaete chrysosporium URM 6181

Investigations on biodegradation of textile effluent by filamentous fungi strains Curvularia lunata URM 6179 and Phanerochaete chrysosporium URM 6181 were performed in static bioreactors under aerated and non-aerated conditions. Spectrophotometric, HPLC/UV and LC-MS/MS analysis were performed as for to confirm, respectively, decolourisation, biodegradation and identity of compounds in the effluent. Enzymatic assays revealed higher production of enzymes laccase (Lac), lignin peroxidase (LiP) and manganese-dependent peroxidase (MnP) by P. chrysosporium URM 6181 in aerated bioreactor (2020; 39 and 392 U/l, respectively). Both strains decolourised completely the effluent after ten days and biodegradation of the most predominant indigo dye was superior in aerated bioreactor (96%). Effluent treated by P. chrysosporium URM 6181 accumulated a mutagenic metabolite derived from indigo. The C. lunata URM 6179 strain, showed to be more successful for assure the environmental quality of treated effluent. These systems were found very effective for efficient fungal treatment of textile effluent.

Production of lipids containing high levels of docosahexaenoic acid from empty palm fruit bunches by Aurantiochytrium sp. KRS101

The oleaginous microalga Aurantiochytrium sp. KRS101 was cultivated in enzymatic hydrolysates of alkali-pretreated empty palm fruit bunches (EFBs), without prior detoxification process. The maximal levels of lipid and docosahexaenoic acid synthesized were 12.5 and 5.4 g L⁻¹ after cultivation for 36 h. Similar lipid levels were also obtained via simultaneous saccharification and cultivation. The results suggested that EFB is a promising source for production of useful lipids by the microalgal strain.