Cunninghamella elegans biomass optimisation for textile wastewater biosorption treatment: an analytical and ecotoxicological approach

The effect of pre-treatments on the composition of Cunninghamella elegans biomass and on its biosorption yields in the treatment of simulated textile wastewaters was investigated. The inactivated biomass was subjected to physical treatments, such as oven drying and lyophilisation, and chemical treatments using acid or alkali. The wastewater colour, COD and toxicity variations were evaluated. The lyophilisation sped up the biosorption process, whereas the chemical pre-treatment changed the affinity of biomass for different dyes. The alkali per-treated biomass achieved the highest COD reduction in the treatment of alkali wastewaters, probably because no release of alkali-soluble biomass components occurred under the alkaline pH conditions. Accordingly, only the acid pre-treated biomass decreased the COD of the acidic effluent. The ecotoxicity test showed significant toxicity reduction after biosorption treatments, indicating that decolourisation corresponds to an actual detoxification of the treated wastewaters. Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analyses of biomasses allowed highlighting their main chemical and physical properties and the changes induced by the different pre-treatments, as well as the effect of the chemical species adsorbed from wastewaters.     

Treatment and kinetic modelling of a simulated dye house effluent by enzymatic catalysis

Biocatalytic treatment of a synthetic dye house effluent, simulating a textile wastewater containing various reactive dyestuffs (Reactive Yellow 15, Reactive Red 239 and Reactive Black 5) and auxiliary chemicals, was investigated in a batch reactor using a commercial laccase. A high decolourisation (above 86%) was achieved at the maximum wavelength of Reactive Black 5. The decolourisation at the other dyes wavelengths (above 63% for RY15 and around 41% for RR239) and the total decolourisation based on all the visible spectrum (around 55%) were not so good, being somewhat lower than in the case of a mixture of the dyes (above 89% for RB5, 77% for RY15, 68% for RR239 and above 84% for total decolourisation). Even so, these results suggest the applicability of this method to treat textile dyeing wastewaters. Kinetic models were developed to simulate the synthetic effluent decolourisation by commercial laccase. The kinetic constants of the models were estimated by minimizing the difference between the predicted and the experimental time courses. The close correlation between the experimental data and the simulated values seems to demonstrate that the models are able to describe with remarkable accuracy the simulated effluent degradation. Water quality parameters such as TOC, COD, BOD₅ and toxicity were found to be under the maximum permissible discharge limits for textile industries wastewaters.     

Fungal and enzymatic remediation of a wine lees and five wine-related distillery wastewaters

The aim of this work was to characterise wine-related wastewaters and ascertain the wastewater concentrations that were optimal for treatment by Trametes pubescens. Laccase production was also monitored. Crudely purified laccase was tested independently to determine its role in phenolic compounds degradation and colour change. The fungal treatment resulted in decreases in the wastewater chemical oxygen demand of up to 83+/-2.1%, phenolic compounds of 87+/-1.6% and colour of 88+/-4.7%. Although laccase treatment lowered total phenolics by up to 61+/-0.5%, the colour was increased by up to 160+/-5%, indicating the formation of colour-rich compounds. Trametes pubescens MB 89 greatly improved the quality of all six wastewaters tested, although two wastewaters had to be diluted to below 50% to allow for bioremediation by the submerged fungal culture. Laccase synthesis greater than 1500 U/l was obtained in all wastewaters, with a maximum of 8997 U/l. The complete fungal system was found to be superior to enzymatic treatment alone. Enzymatic treatment reduced the total phenols but did little to improve the colour of the wastewaters, and in the case of wine lees significantly increased the colour.     

Decolourisation of mushroom farm wastewater by <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis>

Mushroom production on coffee pulp as substrate generates an intense black residual liquid, which requires suitable treatment. In the present study, Pleurotus ostreatus growth in wastewater from mushroom farm was evaluated as a potential biological treatment process for decolourisation as well as to obtain biomass (liquid inoculum). Culture medium components affecting mycelial growth were determined, evaluating colour removal. Laccase activity was monitored during the process. P. ostreatus was able to grow in non diluted WCP. Highest biomass yield was obtained when glucose (10 g/l) was added. The addition of this carbon source was necessary for efficient decolourisation. Agitation of the culture improved biodegradation of WCP as well as fungal biomass production. Laccase and manganese-independent peroxidase activities were detected during fungal treatment of the WCP by P. ostreatus CCEBI 3024. The laccase enzyme showed good correlation with colour loss. Both wastewater colour and pollution load (as chemical oxygen demand) decreased more than 50% after 10 days of culture. Phenols were reduced by 92%.     

Decolourisation of cotton bleaching effluent in a continuous fluidized-bed bioreactor using wood rotting fungus

A continuous fluidized-bed bioreactor was developed for the decolourisation of cotton bleaching effluent with a wood rotting fungus. Different initial concentrations of effluent were tested with either glucose or starch as co-substrates. With this system, 75–80% colour removal was achieved with an initial A400 of 4.7, using a 3 day-retention time. It showed high and stable decolourisation activity in long term continuous operation. © Rapid Science Ltd. 1998     

Decolourisation of model and industrial dyes by mitosporic fungi in different culture conditions

Six mitosporic fungi belonging to five species (Aspergillus flavus var. flavus, Aspergillus ochraceus, Cladosporium cladosporioides, Penicillium glabrum and Penicillium verrucosum) were selected from a screening on 258 fungal strains as the most promising for their ability to remove 2 model dyes in solid conditions. Hence they were tested in liquid conditions for their ability to decolourise 3 model dyes and 9 industrial dyes widely used in the textile industry. The influence of the culture medium, particularly its carbon:nitrogen ratio, on biomass development and decolourisation capacity was considered. All the strains were able to grow in the dyed media and displayed various degrees of decolourisation according to the dye and culture medium. The decolourisation was due to biosorption phenomena. Aspergillus ochraceus performed the highest decolourisation yield being able to remove all dyes over 90%. This strain was also found very effective, both in the living and inactivated form, against simulated effluents that mimicked the recalcitrance of real wastewaters being composed of ten different dyes at high concentration (1,000 ppm), in saline solution.     

Decolourisation of a pigment plant effluent by Pycnoporus cinnabarinus in a packed-bed bioreactor

Summary The decolourisation of wastewater from a pigment plant by the white-rot fungus Pycnoporus cinnabarinus was studied in a packed-bed bioreactor. Decolourisation was first observed 48 to 72 h after inoculation and was followed using UV/VIS spectrophotometry. An assessment of the inhibitory properties of the effluent on the growth of Pycnoporus cinnabarinus showed that this fungus can tolerate high levels of potentially toxic waste.     

Chromium removal from a real tanning effluent by autochthonous and allochthonous fungi

Heavy metals represent an important ecological and health hazard due to their toxic effects and their accumulation throughout the food chain. Conventional techniques commonly applied to recover chromium from tanning wastewaters have several disadvantages whereas biosorption has good metal removal performance from large volume of effluents. To date most studies about chromium biosorption have been performed on simulated effluents bypassing the problems due to organic or inorganic ligands present in real industrial wastewaters that may sequestrate the Cr(III) ions. In the present study a tanning effluent was characterized from a mycological point of view and different fungal biomasses were tested for the removal of Cr(III) from the same tanning effluent in which, after the conventional treatments, Cr(III) amount was very low but not enough to guarantee the good quality of the receptor water river. The experiments gave rise to promising results with a percentage of removed Cr(III) up to 40%. Moreover, to elucidate the mechanisms involved in biosorption process, the same biomasses were tested for Cr(III) removal from synthetic aqueous solutions at different Cr(III) concentrations.     

Influence of culture parameters on paper mill effluent decolourization by a white rot fungus Ganoderma lucidum

Efficacy of a white rot fungus G. lucidum for reduction of colour of paper mill effluent under various growth conditions was evaluated. G. lucidum cultured in IBME medium supported maximum colour reduction on 18th day of fungal growth. The optimization of growth parameters further improved colour reduction. The 18 day old culture at 4 g/l inoculum concentration resulted in maximum decolourization (89%) of the effluent with pH adjusted to 6.5 at 35 degrees C along with maximum reduction in biological oxygen demand and chemical oxygen demand. Relative contribution of lignin peroxidase and laccase to the decolourization of paper mill effluent by G. lucidum was also observed.     

Review paper on current technologies for decolourisation of textile wastewaters: perspectives for anaerobic biotechnology

Dyes are natural and xenobiotic compounds that make the world more beautiful through coloured substances. However, the release of coloured wastewaters represents a serious environmental problem and a public health concern. Colour removal, especially from textile wastewaters, has been a big challenge over the last decades, and up to now there is no single and economically attractive treatment that can effectively decolourise dyes. In the passed years, notable achievements were made in the use of biotechnological applications to textile wastewaters not only for colour removal but also for the complete mineralization of dyes. Different microorganisms such as aerobic and anaerobic bacteria, fungi and actinomycetes have been found to catalyse dye decolourisation. Moreover, promising results were obtained in accelerating dye decolourisation by adding mediating compounds and/or changing process conditions to high temperatures. This paper provides a critical review on the current technologies available for decolourisation of textile wastewaters and it suggests effective and economically attractive alternatives.     

Biosorption of simulated dyed effluents by inactivated fungal biomasses

Treatment of dyed effluents presents several problems mainly due to the toxicity and recalcitrance of dyestuffs. Innovative technologies, such as biosorption, are needed as alternatives to conventional methods to find inexpensive ways of removing dyes from large volumes of effluents. Inactivated biomasses do not require a continuous supply of nutrients and are not sensitive to the toxicity of dyes or toxic wastes. They can also be regenerated and reused in many cycles and are both safe and environment-friendly. The sorption capacities (SC) of autoclaved biomasses of three Mucorales fungi (Cunninghamella elegans, Rhizomucor pusillus and Rhizopus stolonifer), cultured on two different media, were evaluated against simulated effluents containing concentrations of 1000 and 5000 ppm of a single dye and a mix of 10 industrial textile dyes in batch experiments. SC values of up to 532.8 mg of dye g(-1) dry weight of biomass were coupled with high effluent decolourisation percentages (up to 100%). These biomasses may thus prove to be extremely powerful candidates for dye biosorption from industrial wastewaters. Even better results were obtained when a column system with the immobilised and inactivated biomass of one fungus was employed.     

Comparison of the performance of one stage and two stage sequential anaerobic-aerobic biological processes for the treatment of reactive-azo-dye-containing synthetic wastewaters

In the present study the performance of anaerobic-aerobic one and two stage processes for the biological treatment of synthetic wastewaters containing Reactive Black 5 (RB5) were studied and compared with each other. In both processes the majority of colour removal by biodegradation occurred under anaerobic environment. The colour change under aerobic conditions was correlated with extent of anaerobic decolourisation in the preceding phase/stage of the process. Partial mineralisation of the anaerobic dye metabolites, roughly to the same extent, was achieved aerobically in both one stage and two stage processes. The majority of COD was removed in the anaerobic stage for two stage processes and aerobic stage in one stage processes. In one stage processes, the exposure of anaerobic sludge to alternating anaerobic-aerobic environment decreased anaerobic decolourisation efficiency and COD removal; when employing activated sludge, the same exposure enhanced anaerobic substrate utilisation whereas the effect on the anaerobic decolourisation efficiency depended on RB5 concentration. The comparative performance of one and two stage processes in terms of overall dye decolourisation depended on RB5 concentration. Both types of processes brought about similar overall COD removal. Increase in RB5 concentration, in the range studied, resulted in decrease in overall COD removal for both processes.     

Capacity of <Emphasis Type="Italic">Aspergillus niger</Emphasis> to Degrade Anionic Surfactants and Coproduce the Detergent Compatible Enzymes

The capacity of fungus Aspergillus niger to degrade anionic surfactants (AS) and coproduce the detergent compatible enzymes in a liquid Czapek-Dox medium supplemented with 0.3% powder detergent Merix (Henkel, Serbia) was examined in this study. The fungus was isolated from wastewater of Lepenica River (Kragujevac, Serbia), at a place where municipal wastewater discharged into the river. The concentration of AS in tested detergent and detergent-supplemented culture media was determined using a methylene blue active substances assay. The physico-chemical and biochemical changes of pH, redox potential, biomass dry weight, activities of alkaline protease and α-amylase were evaluated during fungal growth from 3-rd to 16- th day. The detergent caused an inhibitory effect on fungal growth and biomass dry weight (about 51.4%). Nevertheless, A. niger decomposed approximately 180.2 μg/mL or 30% of AS after 16 days. The results also showed that activities of alkaline protease and α-amylase were enhanced in presence of tested detergent for 372.0 and 12.7%, respectively. Overall, the obtained results indicate the potential application of fungus in wastewater treatment and detergent industry.     

Influence of Culture Medium on Fungal Biomass Composition and Biosorption Effectiveness

Zygomycetes such as Cunninghamella elegans seem to be promising biosorbents for pollutants removal from wastewaters because of their particular cell wall characteristics. In this article the effect of ten culture media on C. elegans biomass composition was investigated by means of Fourier transform infra red spectroscopy (FTIR). Biomasses grown on starches from potatoes and cereals were characterised by high amount of chitin and polysaccharides, the glucose gave rise to a biomass rich in acidic polysaccharides and lipids. By contrast, biomasses grown on corn steep liquor were poor in acidic polysaccharides and, when N sources and micronutrients were added, rich in proteins. The lipid content of the biomass generally increased by halving nutrients. Biosorption yields of these biomasses towards four wastewater models were assessed in terms of colour, salts and toxicity reduction. The biomasses rich in proteins and acid polysaccharides were less effective in removing reactive and direct dyes, whereas those rich in cationic polysaccharides showed a higher affinity for these dyes. Both chromatography and FTIR analyses showed that biomasses cultured in halved C and N had the highest affinity for salts. The wastewaters detoxification was quite always achieved, with values often lower that the Italian legal threshold limit.     

Studies on decolourization, degradation and detoxification of chlorinated lignin compounds in kraft bleaching effluents by Ceriporiopsis subvermispora

Ceriporiopsis subvermispora CZ-3, a wood degrading white rot fungus, was able to decolourize and degrade the first extraction stage effluent from kraft pulp bleaching at lower co-substrate concentration than the basidiomycetes previously investigated. With glucose at 1 g l⁻¹, this fungus removed up to 90% colour, 45% COD, 62% lignin, 32% AOX, and 36% EOX in 48 h at temperatures of 30–35°C and pH 4.0–4.5. In the absence of glucose, the fungus removed up to 62% of the colour. Significant reduction in chlorinated aromatic compounds was observed and toxicity to zebra fish was completely eliminated. The fungal mycelium could be immobilized in polyurethane foam and used repeatedly to treat batches of effluent. The molecular weight of chlorolignins was substantially reduced.     

Decolourisation of Acid Violet 7 with complex pellets of white rot fungus and activated carbon

Complex mycelium pellets of a white rot fungus, Trametes versicolor, with activated carbon powder were prepared and investigated for decolourisation of an azo dye, Acid Violet 7. The pellets had a black core of activated carbon powder that was surrounded by a layer of white fungal mycelium. Compared to the activated carbon powder, the mycelium pellets (activated carbon free), and the mycelium pellets plus the activated carbon powder that was added into a dye solution, the complex pellets showed the highest and the most stable activity of dye decolourisation in batch cultures. The high decolourisation rate of the complex pellets was attributed not only to dye adsorption by the activated carbon in the complex pellets, but also to adsorption of extracellular enzymes and other reagents involved in dye decolourisation as well as the closeness between the dye molecules and the fungal cells. The complex pellets were further evaluated in a fluidized-bed reactor in two operation modes: a continuous flow feeding and a repeated-batch feeding. The latter gave higher and more stable decolourisation efficiency than the former. Production of laccase in flask culture and the fluidized-bed bioreactor was also compared.     

Decolourisation of effluent from the textile industry by a microbial consortium

Summary A microbial consortium, PDW, was isolated capable of the rapid decolourisation of commercially important textile dyes under anaerobic conditions. Decolourisation was dependent upon the presence of a carbon and energy source in addition to the textile dyes. PDW was capable of dye decolourisation when utilising cheap and readily available carbon sources such lactose, starch and distillery waste. PDW removed 76% of colour from textile plant effluent after 3 days.     

Biodegradation of different molecular-mass polyphenols derived from olive mill wastewaters by Geotrichum candidum

The decolourisation of fresh and stored olive mill wastewaters (OMW) and the biodegradation of three groups (F1, F2 and F3) of phenolic compounds by Geotrichum candidum were investigated. Separated phenolic compounds derived from natural OMW ultrafiltration using membranes with a cutoff 2and 100 kDa. G. candidum growth on fresh OMW decreased pH and reduced COD and colour of 75% and 65%, respectively. However, on the stored-black OMW a failure of COD and colour removal were observed. G. candidum activity on this later substrate was enhanced by the addition of a carbon source easily metabolised, misleading an improvement of the COD reduction and decolourization that reached 58% and 48%, respectively. Growth of G. candidum in the presence of F2 or F3 polyphenolic fractions induced high decolourisation and depolymerisation of phenolic compounds. Whereas, very week decolourisation and biodegradation were observed with F1 fraction. Moreover, the highest levels of lignin peroxidase (LiP) and manganese peroxidase (MnP) activities were obtained in the presence of F2 fraction. These results showed that increasing of molecular-mass of aromatics led to an increase in levels of depolymerisation, decolourisation and COD removal by G. candidum culture.     

De-colourization of textile effluent using immobilized Geotrichum candidum: an insight into mycoremediation

Textile effluent is generally complicated to manage because of its extremely noxious and recalcitrant coloured compositions. Mycoremediation is an extensively used strategy for the competent degradation of hazardous pollutants present in textile effluent. Fungus could be immobilized in synthetic or natural matrices. The current study shows the decolourization of the textile effluent by 85·5 and 98·5% within 6 h using suspended and immobilized fungus, Geotrichum candidum with optimized parameters like inoculum size (5%), pH (4·5), and temperature (30°C). To maintain a high biomass of fungal population and enhance the retention of fungal strain in the contaminated sites, the fungi need to be immobilized. Hence, the fungus was immobilized naturally onto the selected inert support that is, coconut fibres by the means of adsorption, where they grew as active films on the fibres after being grown in the culture broth. The optimized process parameters of inoculum size, fibre quantity and agitation speed for immobilized G. candidum were 5%, 2·2 g l⁻¹ of effluent and 100 rev min⁻¹ respectively. High level of laccase (22 and 25 U l⁻¹ in suspended and immobilized fungal cells treatment respectively) was observed during the process of decolourization and it was found that decolourization was directly proportional to the laccase activity. The UV–vis, FTIR, ¹H NMR and GC-MS analyses of treated textile industrial wastewater revealed the degradation of toxic pollutants in the textile effluent and formation of lower molecular weight intermediates. The study revealed a higher efficacy of immobilized G. candidum in comparison to suspended fungal culture, employing ligninolytic enzyme laccase, which catalyzes the degradation/transformation of aromatic dyes in the textile effluent thus decolourizing it.     

Detoxification and mineralization of Acid Blue 74: study of an alternative secondary treatment to improve the enzymatic decolourization

Many reports describe the decolourization of dyes by fungal enzymes. However, these enzymes do not contribute to dye mineralization but only to its biotransformation into less coloured or colourless molecules persisting in solution. Therefore, it is essential to analyse the identity of the metabolites produced during enzymatic treatments and its biodegradation into an appropriate system. The present work examines the decolourization/detoxification of a simulated effluent (containing Acid Blue 74) by fungal enzymes and proposes a secondary treatment using an anaerobic system to improve the enzymatic decolourization through the complete mineralization of the dye. Ligninolytic enzymes were produced by solid culture using the thermo-tolerant fungus Fomes sp. EUM1. The enzymes produced showed a high rate of decolourization (>95 % in 5 h) and were stable at elevated temperature (40 °C) and ionic strength (NaCl, 50 mM). Isatin-5-sulphonic acid was identified via ¹H-NMR as oxidation product; tests using Daphnia magna revealed the non-toxic nature of this compound. To improve the enzymatic degradation and avoid coupling reactions between the oxidation products, the effluent was subjected to an anaerobic (methanogenic) treatment, which achieved high mineralization efficiencies (>85 %). To confirm the mineralization of isatin-5-sulphonic acid, a specific degradation study, which has not been reported before, with this single compound was conducted under the same conditions; the results showed high removal efficiencies (86 %) with methane production as evidence of mineralization. These results showed the applicability of an anaerobic methanogenic system to improve the enzymatic decolourization/detoxification of Acid Blue 74 and achieve its complete mineralization.