Sulphonated aromatic pollutants. Limits of microbial degradability and potential of phytoremediation

Deciphering the black box of microbial community of common effluent treatment plant through integrated metagenomics: Tackling industrial effluent

Identifying the microbial community and their functional potential from different stages of common effluent treatment plants (CETP) can enhance the efficiency of wastewater treatment systems. In this study, wastewater metagenomes from 8 stages of CETP were screened for microbial diversity and gene profiling along with their corresponding degradation activities. The microbial community displayed 98.46% of bacterial species, followed by Eukarya (0.10%) and Archaea 0.02%. At the Phylum level, Proteobacteria (28.8%) was dominant, followed by Bacteroidetes (16.1%), Firmicutes (11.7%), and Fusobacteria (6.9%) which are mainly capable of degrading the aromatic compounds. Klebsiella pneumoniae, Wolinella succinogenes, Pseudomonas stutzeri, Desulfovibrio vulgaris, and Clostridium sticklandii were the most prevalent species. The functional analysis further demonstrated the presence of enzymes linked with genes/pathways known to be involved in the degradation/metabolization of aromatic compounds like benzoate, bisphenol, 1,2-dichloroethane phenylalanine. This information was further validated with the whole genome analysis of the bacteria isolated from the CETP. We anticipate that integrating both shotgun and whole-genome analyses can reveal the rich reservoir for novel enzymes and genes present in CETP effluent that can contribute to designing efficient bioremediation strategies for the environment in general CETP system, in particular.

Remediation of emerging environmental pollutants: A review based on advances in the uses of eco-friendly biofabricated nanomaterials

The increased environmental pollutants due to anthropogenic activities are posing an adverse effects and threat on various biotic forms on the planet. Heavy metals and certain organic pollutants by their toxic persistence in the environment are regarded as significant pollutants worldwide. In recent years, pollutants exist in various forms in the environment are difficult to eliminate by traditional technologies due to various drawbacks. This has lead to shifting of research for the development of cost-effective and efficient technologies for the remediation of environmental pollutants. The adaption of adsorption phenomenon from the traditional technologies with the modification of adsorbents at nanoscale is the trended research for mitigating the environmental pollutants with petite environmental concerns. Over the past decade, the hidden potentials of biological sources for the biofabrication of nanomaterials as bequeathed rapid research for remediating the environmental pollution in a sustainable manner. The biofabricated nanomaterials possess an inimitable phenomenon such as photo and enzymatic catalysis, electrostatic interaction, surface active site interactions, etc., contributing for the detoxification of various pollutants. With this background, the current review highlights the emerging biofabricated nano-based adsorbent materials and their underlying mechanisms addressing the environmental remediation of persistent organic pollutants, heavy metal (loid)s, phytopathogens, special attention to the reduction of pathogen-derived toxins and air pollutants. Each category is illustrated with suitable examples, fundamental mechanism, and graphical representations, along with societal applications. Finally, the future and sustainable development of eco-friendly biofabricated nanomaterial-based adsorbents is discussed.

Identification of Sulfonated and Hydroxy-Sulfonated Polychlorinated Biphenyl (PCB) Metabolites in Soil: New Classes of Intermediate Products of PCB Degradation?

In this paper we describe the identification of two classes of contaminants: sulfonated-PCBs and hydroxy-sulfonated-PCBs. This is the first published report of the detection of these chemicals in soil. They were found, along with hydroxy-PCBs, in soil samples coming from a site historically contaminated by the industrial production of PCBs and in background soils. Sulfonated-PCB levels were approximately 0.4-0.8% of the native PCB levels in soils and about twice the levels of hydroxy-sulfonated-PCBs and hydroxy-PCBs. The identification of sulfonated-PCBs was confirmed by the chemical synthesis of reference standards, obtained through the sulfonation of an industrial mixture of PCBs. We then reviewed the literature to investigate for the potential agents responsible for the sulfonation. Furthermore, we predicted their physicochemical properties and indicate that, given the low pK_a of sulfonated- and hydroxy-sulfonated-PCBs, they possess negligible volatility, supporting the case for in situ formation from PCBs. This study shows the need of understanding their origin, their role in the degradation path of PCBs, and their fate, as well as their (still unknown) toxicological and ecotoxicological properties.

The effect of oil sludge contamination on morphological and physiological characteristics of some tree species

Although petroleum plays an important part in world economy, its exploitation can bring about a great deal of contamination in soil. To select the tree species being tolerant to soil pollution, a pot experiment has been carried out to assess and compare the growth potential of the seedlings of black locust (Robinia pseudoacacia L.), Chinaberry (Melia azedarach L.), Ailantos (Ailanthus altissima Mill.) and Ash (Fraxinus rotundifolia Mill.) in petroleum-hydrocarbon contaminated soils. The seeds of the mentioned species were subjected to different oil sludge concentrations (0, 10, 20 and 40%) for a growth season of 240 days and then seedling emergence, growth performance, biomass production, photosynthetic parameters and heavy metal absorption were measured to find the species with higher resistantce. For all the species, seedling emergence was significantly reduced under the soil pollution among which F. rotundifolia exhibited a better performance. Besides, growth and biomass of F. rotundifolia and R. pseudoacacia were seldom influenced by oil sludge. In addition, seedlings of A. altissima accumulated higher percentage of the heavy metals (particularly Ni, Cu, Cd) in their leaves by virtue of their wider leaf surface area. This study provides valuable insights into phytoremediation of sites contaminated by oil sludge, using tree species.

Characterization of physiochemical and anatomical features associated with enhanced phytostabilization of copper in Bruguiera cylindrica (L.) Blume

Copper is an essential micronutrient for normal plant metabolism and it is involved in number of physiological processes in plants but at the same time, at concentrations above threshold level, it acts as a potential stress factor. In this study, the phytoremediation potential of Bruguiera cylindrica (L.) Blume with respect to Cu was evaluated for the first time. Various physiochemical and anatomical parameters were analyzed in three-month-old healthy plantlets of B. cylindrica on exposure to different concentrations of CuSO₄ (0, 0.05, 0.15, and 0.25 mM)for 20 d. Higher uptake and accumulation of Cu in the roots indicates that the roots are the primary site of Cu accumulation and thus the plant perform as an excluder. Tolerance index values (TI > 60) reveals the phytoremediation potential of this plant. Metabolites are accumulated in plants to cope up with the oxidative damage due to Cu stress. Increased rate of proline and free amino acids content and soluble sugar content especially in leaves of B. cylindrica subjected to CuSO₄ contributes toward higher osmolality so as to counter the reduced water transport from roots. Nonenzymatic antioxidants like ascorbic acid, glutathione, and phenolics are the ROS scavenging compounds in the Defense system of B. cylindrica toward higher concentrations of CuSO₄, and of these, phenolics accumulation plays greater role in the antioxidative function in B. cylindrica in response to Cu stress. The histochemistry of B. cylindrica revealed the prominent occurrence of star-shaped calcium oxalate crystals when exposed to 0.25 mM CuSO₄, and it seems to be a prominent defense mechanism under Cu stress. Also a remarkable finding was the accumulation of Cu in the xylem vessels of plants on exposure of 0.25 mM CuSO₄ as compared to control. The infrared spectra were analyzed to compare the functional groups in the phenolics and carbohydrate constituents of control and CuSO₄-treated B. cylindrica plantlets and it indicated that carboxyl and hydroxyl groups are involved in the Cu binding so as to achieve tolerance to Cu. Thus this study revealed the potential role of B. cylindrica as a promising candidate for phytostabilization of copper.

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

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

Structure and function of the microbial consortia of activated sludge in typical municipal wastewater treatment plants in winter

To better understand the relationship between the environmental variables and microbial communities of activated sludge, we took winter samples from different biological treatment units (anaerobic, oxic, etc) from the WWTP's of a number of Chinese cities. Differences in influent organic components and activated sludge microbial communities were identified by gas chromatography-mass spectrometry and high-throughput sequencing technology, respectively. Liquid nitrogen grinding pretreatment of samples was found to aid in the obtaining of a more bio-diversified sample. Influent type and dissolved oxygen concentration influenced the activated sludge microbial community structure. Nitrospira, Caldilineaceae and Anaerolineaceae were highly related to domestic wastewater treatment systems, whereas Thauera was the most abundant putative refractory aromatic hydrocarbon decomposer found in industrial wastewater treatment systems. Within the influent composition, we speculate that Thauera, Macellibacteroides and Desulfomicrobium are the key functional genera of the anaerobic environment of the textile dyeing industry wastewater treatment systems, whilst Thauera and Thiobacillus are key functional microbes in fine chemical wastewater treatment systems.

Ultrasound based AOP for emerging pollutants: from degradation to mechanism

Ultrasound is known to degrade organic compounds by pyrolysis and by the reaction of free radicals. In this work, sonolytic degradation of an identified water pollutant, coomassie brilliant blue (CBB), has been carried out in pure water as well as in river water. In the case of pure water, 90 % degradation was obtained after 30 min of sonication (350 kHz frequency, 60 W power), whereas in river water, the same efficiency was achieved only after 90 min. The degradation was also performed in the presence of varying concentration of (10-100 mg L^-1) inorganic ions such as chloride, sulfate, nitrate, bicarbonate, and carbonate ions which were detected in the river water sample. Higher concentration of chloride enhanced the degradation due to the salting out mechanism. The enhancement of degradation in the presence of nitrate is mainly due to the change in the surface potential at the interface of the cavitating bubble. Bicarbonate ion and carbonate ion enhanced the degradation due to the involvement of carbonate radicals. A possible degradation mechanism is proposed based on the product profile determined by LC-Q-ToF-MS. The low efficiency of degradation in river water compared to that in pure water is likely due to the increased rate of bubble dissolution or escape of bubbles (degassing effect), and the scavenging of ^•OH by the organic content (high chemical oxygen demand (COD)).

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

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

The Hydractinia echinata test-system. III: Structure-toxicity relationship study of some azo-, azo-anilide, and diazonium salt derivatives

Structure-toxicity relationships for a series of 75 azo and azo-anilide dyes and five diazonium salts were developed using Hydractinia echinata (H. echinata) as model species. In addition, based on these relationships, predictions for 58 other azo-dyes were made. The experimental results showed that the measured effectiveness Mlog(1/MRC₅₀) does not depend on the number of azo groups or the ones corresponding to metobolites, but it is influenced by the number of anilide groups, as well as by the substituents’ positions within molecules. The conformational analysis pointed out the intramolecular hydrogen bonds, especially the simple tautomerization of quinoidic (ST_OH) or aminoidic (ST_NH2) type. The effectiveness is strongly influenced by the “push-pull” electronic effect, specific to two hydroxy or amino groups separated by an azo moiety (double alternate tautomery, (DAT), to the –COOH or –SO₃H groups which are located in ortho or para position with respect to the azo group. The levels of the lipophylic/hydrophilic, electronic and steric equilibriums, pointed out by the Mlog(1/MRC₅₀) values, enabled the calculation of their average values Clog(1/MRC₅₀) (“Köln model”), characteristic to one derivative class (class isotoxicity). The azo group reduction and the hydrolysis of the amido/peptidic group are two concurrent enzymatic reactions, which occur with different reaction rates and mechanisms. The products of the partial biodegradation are aromatic amines. No additive or synergic effects are noticed among them.

Enhanced phytotransformation of Navy Blue RX dye by Petunia grandiflora Juss. with augmentation of rhizospheric Bacillus pumilus strain PgJ and subsequent toxicity analysis

This study reveals the beneficial synergistic phytoremediation potential of Petunia grandiflora Juss. with its rhizospheric bacterial isolate Bacillus pumilus strain PgJ to decolorize reactive Navy Blue RX (NBRX) dye by their active enzymatic machinery. In vitro cultures of P. grandiflora and B. pumilus gave 80.01% and 76.80% while their consortium decolorized NBRX up to 96.86% within 36 h. Significant induction in the enzyme activities of lignin peroxidase (207%), tyrosinase (133%), laccase (161%), riboflavin reductase (78%) were seen in the roots of tissue cultured plants while enzymes tyrosinase (660%), laccase (689%), riboflavin reductase (528%) were induced significantly in the B. pumilus cells. Metabolites of treated NBRX were analyzed using UV-vis spectroscopy, gas chromatography and biotransformation was visualized using high performance thin layer chromatography profile. Metabolites of the dye exhibited reduced phytotoxicity Sorghum vulgare and Phaeseolus mungo and significant reduction in cytogenotoxicity on Allium cepa roots when compared to NBRX.

Is phytoremediation a sustainable and reliable approach to clean-up contaminated water and soil in Alpine areas?

BACKGROUND, AIM AND SCOPE

Phytoremediation does exploit natural plant physiological processes and can be used to decontaminate agricultural soils, industrial sites, brownfields, sediments and water containing inorganic and organic pollutants or to improve food chain safety by phytostabilisation of toxic elements. It is a low-cost and environment friendly technology targetting removal, degradation or immobilisation of contaminants. The aim of the present review is to highlight some recent advances in phytoremediation in the Alpine context.

MAIN FEATURES

Case studies are presented where phytoremediation has been or can be successfully applied in Alpine areas to: (1) clean-up industrial wastewater containing sulphonated aromatic xenobiotics released by dye and textile industries; (2) remediate agricultural soils polluted by petroleum hydrocarbons; (3) improve food chain safety in soils contaminated with toxic trace elements (As, Co, Cr and Pb); and (4) treat soils impacted by modern agricultural activities with a special emphasis on phosphate fertilisation.

CONCLUSIONS, RECOMMENDATIONS AND PERSPECTIVES

Worlwide, including in Alpine areas, the controlled use of appropriate plants is destined to play a major role for remediation and restoration of polluted and degraded ecosystems, monitoring and assessment of environmental quality, prevention of landscape degradation and immobilisation of trace elements. Phytotechnologies do already offer promising approaches towards environmental remediation, human health, food safety and sustainable development for the 21st century in Alpine areas and elsewhere all over the world.

The role of Aster amellus Linn. in the degradation of a sulfonated azo dye Remazol Red: a phytoremediation strategy

Phytoremediation is a novel and promising approach for the treatment of pollutants. This study did explore the potential of Aster amellus Linn. to decolorize a sulfonated azo dye Remazol Red (RR), a mixture of dyes and a textile effluent. Induction in the activities of lignin peroxidase, tyrosinase, veratryl alcohol oxidase and riboflavin reductase was observed during RR decolorization, suggesting their involvement in the metabolism of RR. UV-Visible absorption spectrum, HPLC and FTIR analysis confirmed the degradation of RR. Four metabolites after the degradation of the dye were identified as 2-[(3-diazenylphenyl) sulfonyl] ethanesulfonate, 4-amino-5-hydroxynaphthalene-2,7-disulfonate, naphthalene-2-sulfonate and 3-(1,3,5-triazin-2-ylamino)benzenesulfonate by using GC/MS. Textile effluent and mixture of dyes showed 47% and 62% decrease respectively in American Dye Manufacturers Institute value. BOD of textile effluent and mixture of dyes were reduced by 75% and 48% respectively, COD of industrial effluent and mixture of dyes was reduced by 60% and 75% and TOC was reduced by 54% and 69% respectively after the treatment by A. amellus for 60 h; this indicated that the plant can be used for cleaning textile effluents. Toxicity study revealed the phytotransformation of RR into non-toxic products.

Köln-Timişoara Molecular activity combined models toward interspecies toxicity assessment

Aiming to provide a unified picture of computed activity – quantitative structure activity relationships, the so called Köln (ESIP-ElementSpecificInfluenceParameter) model for activity and Timisoara (Spectral-SAR) formulation of QSAR were pooled in order to assess the toxicity modeling and inter-toxicity correlation maps for aquatic organisms against paradigmatic organic compounds. The Köln ESIP model for estimation of a compound toxicity is based on the experimental measurement expressing the direct action of chemicals on the organism Hydractinia echinata so that the structural influence parameters are reflected by the metamorphosis degree itself. As such, the calculation of the structural parameters is absolutely necessary for correct evaluation and interpretation of the evolution of M(easured) and the C(computed) values. On the other hand, the Timişoara Spectral-SAR analysis offers correlation models and paths for H.e. species as well as for four other different organisms with which the toxicity may be inter-changed by means of the same mechanism of action induced by certain common chemicals.

The role of cytochromes P450 and peroxidases in the detoxification of sulphonated anthraquinones by rhubarb and common sorrel plants cultivated under hydroponic conditions

BACKGROUND, AIM AND SCOPE

Sulphonated anthraquinones are precursors of many synthetic dyes and pigments, recalcitrant to biodegradation and thus not eliminated by classical wastewater treatments. In the development of a phytotreatment to remove sulphonated aromatic compounds from dye and textile industrial effluents, it has been shown that rhubarb (Rheum rabarbarum) and common sorrel (Rumex acetosa) are the most efficient plants. Both species, producing natural anthraquinones, not only accumulate, but also transform these xenobiotic chemicals. Even if the precise biochemical mechanisms involved in the detoxification of sulphonated anthraquinones are not yet understood, they probably have cross talks with secondary metabolism, redox processes and plant energy metabolism. The aim of the present study was to investigate the possible roles of cytochrome P450 monooxygenases and peroxidases in the detoxification of several sulphonated anthraquinones.

MATERIALS AND METHODS

Both plant species were cultivated in a greenhouse under hydroponic conditions, with or without sulphonated anthraquinones. Plants were harvested at different times and either microsomal or cytosolic fractions were prepared. The monooxygenase activity of cytochromes P450 toward several sulphonated anthraquinones was tested using a new method based on the fluorimetric detection of oxygen consumed during cytochromes P450-catalysed reactions. The activity of cytosolic peroxidases was measured by spectrophotometry, using guaiacol as a substrate.

RESULTS

A significant activity of cytochromes P450 was detected in rhubarb leaves, while no (rhizome) or low (petioles and roots) activity was found in other parts of the plants. An induction of this enzyme was observed at the beginning of the exposition to sulphonated anthraquinones. The results also indicated that cytochromes P450 were able to accept as substrate the five sulphonated anthraquinones, with a higher activity toward AQ-2,6-SS (0.706 nkat/mg protein) and AQ-2-S (0.720 nkat/mg protein). An activity of the cytochromes P450 was also found in the leaves of common sorrel (1.212 nkat/mg protein (AQ-2,6-SS)), but no induction of the activity occurred after the exposition to the pollutant. The activity of peroxidases increased when rhubarb was cultivated in the presence of the five sulphonated anthraquinones (0.857 nkat/mg protein). Peroxidase activity was also detected in the leaves of the common sorrel (0.055 nkat/mg protein), but in this plant, no significant difference was found between plants cultivated with and without sulphonated anthraquinones.

DISCUSSION

Results indicated that the activity of cytochromes P450 and peroxidases increased in rhubarb in the presence of sulphonated anthraquinones and were involved in their detoxification mechanisms.

CONCLUSIONS

These results suggest the existence in rhubarb and common sorrel of specific mechanisms involved in the metabolism of sulphonated anthraquinones. Further investigation should be performed to find the next steps of this detoxification pathway.

RECOMMENDATIONS AND PERSPECTIVES

Besides these promising results for the phytotreatment of sulphonated anthraquinones, it will be of high interest to develop and test, at small scale, an experimental wastewater treatment system to determine its efficiency. On the other hand, these results reinforce the idea that natural biodiversity should be better studied to use the most appropriate species for the phytotreatment of a specific pollutant.

Metabolism of sulphonated anthraquinones in rhubarb, maize and celery: the role of cytochromes P450 and peroxidases

Sulphonated anthraquinones are precursors of many synthetic dyes and pigments, recalcitrant to biodegradation, and thus contaminating many industrial effluents and rivers. In the development of a phytotreatment to remove sulphonated aromatic compounds, rhubarb (Rheum rhaponticum), a plant producing natural anthraquinones, as well as maize (Zea mays) and celery (Apium graveolens), plants not producing anthraquinones, were tested for their ability to metabolise these xenobiotics. Plants were cultivated under hydroponic conditions, with or without sulphonated anthraquinones, and were harvested at different times. Either microsomal or cytosolic fractions were prepared. The monooxygenase activity of cytochromes P450 towards several sulphonated anthraquinones was tested using a new method based on the fluorimetric detection of oxygen consumed during cytochromes P450-catalysed reactions. The activity of cytosolic peroxidases was measured by spectrophotometry, using guaiacol as a substrate. Results indicated that the activity of cytochromes P450 and peroxidases significantly increased in rhubarb plants cultivated in the presence of sulphonated anthraquinones. A higher activity of cytochromes P450 was also detected in maize and celery exposed to the pollutants. In these two plants, a peroxidase activity was also detected, but without a clear difference between the control plants and the plants exposed to the organic contaminants. This research demonstrated the existence in rhubarb, maize and celery of biochemical mechanisms involved in the metabolism and detoxification of sulphonated anthraquinones. Taken together, results confirmed that rhubarb might be the most appropriate plant for the phytotreatment of these organic pollutants.

Treatment of bromoamine acid wastewater using combined process of micro-electrolysis and biological aerobic filter

The wastewater originated from the production of bromoamine acid was treated in a sequential system of micro-electrolysis (ME) and biological aerobic filter (BAF). Decolorization and COD(Cr) removal rate of the proposed system was investigated with full consideration of the influence of two major controlling factors such as organic loading rate (OLR) and hydraulic retention time (HRT). The removal rate of COD(Cr) was 81.2% and that of chrominance could be up to 96.6% at an OLR of 0.56 kg m(-3)d(-1) when the total HRT was 43.4h. Most of the chrominance was removed by the ME treatment, however, the BAF process was more effective for COD(Cr) removal. The GC-MS and HPLC-MS analysis of the contaminants revealed that 1-aminoanthraquinone, bromoamine acid and mono-sulfonated 1,2-dichlorobenzene were the main organic components in the wastewater. The reductive transformation of the anthraquinone derivatives in the ME reactor improved the biodegradability of the wastewater, and rendered the decolorization. After long-term of operation, it was observed that the predominant microorganisms immobilized on the BAF carriers were rod-shaped and globular. Four bacterial strains with apparent 16S rDNA fragments in the Denaturing Gradient Gel Electrophoresis (DGGE) profiles of BAF samples were identified as Variovorax sp., Sphingomonas sp., Mycobacterium sp., and Microbacterium sp.

Efficient removal of aromatic sulfonates from wastewater by a recyclable polymer: 2-naphthalene sulfonate as a representative pollutant

As a family of hydrophobic ionizable organic compounds, aromatic sulfonates can be present at high levels in industrial wastewaters. They tend to exist as anions over a wide range of pH and cannot be effectively trapped by conventional adsorbents. In the current study, a recyclable acrylic ester polymer (NDA-801) was synthesized for effective removal of aromatic sulfonates from wastewater of high acidity (e.g., pH < 1) and inorganic salts (e.g., approximately 5-10% Na2SO4 in mass), for which sodium 2-naphthalene sulfonate (2-NS) was chosen as a representative target contaminant 2-NS uptake onto NDA-801 increased with the increasing acidity of the solution. The zeta potential of NDA-801 measured at different pH levels as well as batch 2-NS adsorption from methanol/water binary systems demonstrated the favorable roles of electrostatic and hydrophobic interaction in 2-NS adsorption. As compared to a granular activated carbon GAC-1, NDA-801 exhibited much higher removal efficiency and capacity of 2-NS in fixed-bed adsorption. Moreover, the exhausted NDA-801 beads by 2-NS can be completely regenerated by water wash for repeated use, which is more economically desirable than by other regenerants, such as NaOH solution. Continuous column adsorption-regeneration cycles indicated negligible capacity loss of NDA-801 during operation and further validated its feasibility for potential application in associated wastewater treatment.

Decolourization and removal of some organic compounds from olive mill wastewater by advanced oxidation processes and lime treatment

BACKGROUND

Olive mill wastewater (OMW) generated by the olive oil extracting industry is a major pollutant, because of its high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Mediterranean countries are mostly affected by this serious environmental problem since they are responsible for 95% of the worldwide olive-oil production. There are many methods used for OMW treatment, such as adsorption, electro coagulation, electro-oxidation, biological degradation, advanced oxidation processes (AOPs), chemical coagulation, flocculation, filtration, lagoons of evaporation and burning systems, etc. Currently, there is no such economical and easy solution. The aim of this study was to evaluate the feasibility of decolourization and removal of phenol, lignin, TOC and TIC in OMW by UV/H2O2 (AOPs). The operating parameters, such as hydrogen peroxide dosage, times, pH, effect of UV and natural sunlight were determined to find the suitable operating conditions for the best removal. Moreover, there is no study reported in the literature related to the use of

METHODS

OMW was obtained from an olive-oil producing plant (Muğla area of Turkey) which uses a modern production process. No chemical additives are used during olive oil production. This study was realised by using two different UV sources, while taking the time and energy consumption into consideration. These two sources were mercury lamps and natural sunlight. Before starting AOPs experiments, one litre of OMW was treated by adding lime until a pH of 7.00. Then, 100 ml was taken from each sample, and 1 to 10 ml of a 30% H2O2 (Riedel-deHaen) solution was added. These solutions in closed vessels were laid in the natural sunlight for a week and their compositions and colour changes were analysed daily by UV-Vis spectrophotometer. At the end of the one-week period, they were treated with lime. In this study, the effect of changes in the initial pH, times and H2O2 concentrations on removal was investigated. At the end of all experiments, changes in colour, phenol, lignin, TOC and TIC concentrations were analysed according to standard methods.

RESULTS AND DISCUSSION

In the samples exposed to natural sunlight and having an H2/OMW ratio of 3 ml/100 ml, a significant colour removal was achieved approximately 90% of the time at the end of 7 days. When the same samples were treated with lime (pH: up to 7), 99% efficiency was achieved. When phenol and lignin removals were examined in the same concentration, phenol and lignin removal were found 99.5%, 35%, respectively. However, for maximum lignin removal, more use of H2O2 (10 ml H2O2/100 ml OMW) was found to be necessary. Under these conditions, it was found that lignin can be removed by 70%, but to 90% with lime, at the end of a seven-day period. Rate constants obtained in the experiments performed with direct UV were found to be much higher than those of the samples exposed to natural sunlight (k(a)lignin=0.3883>> k(b)lignin=0.0078; k(a)phenol=0.5187>> k(b)phenol = 0.0146). Moreover, it should be remembered in this process that energy consumption may induce extra financial burden for organisations.

CONCLUSIONS

It was found, in general, that colour, lignin, total organic carbon and phenol were removed more efficiently from OMW by using H2O2 UV and lime OMW. Moreover, in the study, lime was found to contribute, both initially and after radical reactions, to the efficiency to a great extent.

RECOMMENDATIONS AND PERSPECTIVES

Another result obtained from the study is that pre-purification carried out with hydrogen peroxide and lime may constitute an important step for further purification processes such as adsorption, membrane processes, etc.

Activation of the heat shock response in plants by chlorophenols: transgenic Physcomitrella patens as a sensitive biosensor for organic pollutants

The ability to detect early molecular responses to various chemicals is central to the understanding of biological impact of pollutants in a context of varying environmental cues. To monitor stress responses in a model plant, we used transgenic moss Physcomitrella patens expressing the beta-glucuronidase reporter (GUS) under the control of the stress-inducible promoter hsp17.3B. Following exposure to pollutants from the dye and paper industry, GUS activity was measured by monitoring a fluorescent product. Chlorophenols, heavy metals and sulphonated anthraquinones were found to specifically activate the hsp17.3B promoter (within hours) in correlation with long-term toxicity effects (within days). At mildly elevated physiological temperatures, the chemical activation of this promoter was strongly amplified, which considerably increased the sensitivity of the bioassay. Together with the activation of hsp17.3B promoter, chlorophenols induced endogenous chaperones that transiently protected a recombinant thermolabile luciferase (LUC) from severe heat denaturation. This sensitive bioassay provides an early warning molecular sensor to industrial pollutants under varying environments, in anticipation to long-term toxic effects in plants. Because of the strong cross-talk between abiotic and chemical stresses that we find, this P. patens line is more likely to serve as a direct toxicity bioassay for pollutants combined with environmental cues, than as an indicator of absolute toxicity thresholds for various pollutants. It is also a powerful tool to study the role of heat shock proteins (HSPs) in plants exposed to combined chemical and environmental stresses.

Screening of plant species for the phytotreatment of wastewater containing sulphonated anthraquinones

Sulphonated anthraquinones are known to be recalcitrant to biodegradation and are not eliminated by traditional wastewater treatment plants, leading to their accumulation in fresh water. Due to the high cost and limited efficiency of existing physical-chemical treatments, alternative cheaper processes are required to remove these compounds from industrial effluents. Four plant species were tested under hydroponic conditions for their ability to treat model effluents contaminated with mono- and disulphonated anthraquinones. Among them, Rheum rabarbarum (rhubarb) showed the most promising results and was chosen for further investigation. The apparent transpiration stream concentration factor obtained with this plant species reached up to 2.5, indicating a strong phytotreatment potential that should be further explored then exploited.

Determination of Linear Alkylbenzenesulfonates and Their Degradation Products in Soils by Liquid Chromatography-Electrospray-Ion Trap Multiple-Stage Mass Spectrometry

Linear alkylbenzenesulfonates (LAS) (C(10)-C(13)) and their degradation products, sulfophenyl carboxylate compounds (SPCs) (C(2)-C(6), C(8), C(11)), have been extracted from soil samples with methanol, isolated, concentrated by solid-phase extraction, and determined by liquid chromatography/negative ion electrospray quadrupole ion-trap tandem mass spectrometry (MS(n)). The ion fragmentation processes and pathways were studied in detail by MS, MS(2), and MS(3). Upon collision-induced dissociation, the deprotonated molecules of LASs render the ethylene-substituted benzenesulfonate ion (m/z 183), the fragmentation of which gave the intense signal at m/z 119, corresponding to the ethylene-substituted phenoxide ion formed by the loss of sulfur dioxide. The fragmentation pattern of SPCs shows that, for the analytes of large carbon atom chains (>5C), the neutral loss of water is favored whereas for those of short carbon atoms chain, the loss of carbon dioxide is more frequent. Multiple reaction monitoring using isolation only for MS and using isolation and fragmentation for MS(2) and MS(3) were used to identify and quantify each compound. The three MS modes have been validated in terms of sensitivity, selectivity, and precision, showing that each MS stage used reduces sensitivity 10 times. Recoveries from soil were higher than 65% at LOQ level for all the analytes tested, except for C(2)-C(4) SPCs by any MS mode, with relative standard deviation lower than 19%. The utility of the method is demonstrated by successfully quantifying real samples treated with these products. Quantification limits for the methodology developed in this work ranged from 0.5 to 50 microg kg(-1) by MS, from 2 to 400 microg kg(-1) by MS(2), and from 20 to 4000 microg kg(-1) by MS(3). Concentration levels of LASs and SPCs-ranging from 0.1 to 15 mg kg(-1)-were found in soil samples amended with sludges, thus indicating their input and persistence in the soil compartment.