Plants are known to remediate dyes, metals and emerging contaminants from wastewaters. Vetiveria zizanioides, a perennial bunchgrass showed removal of Remazol Red (RR, 100 mg/L) up to 93% within ...40 h. Root and shoot tissues of V. zizanioides revealed induction in dye degrading enzymes viz. lignin peroxidase by 2.28 and 1.43, veratryl alcohol oxidase 2.72 and 1.60, laccase 6.15 and 3.55, and azo reductase 2.17 and 2.65-fold, respectively, during RR decolorization. Substantial increase was observed in the contents of chlorophyll a, chlorophyll b, and carotenoids in the plant leaves during treatment. Anatomical studies of roots, HPLC and GC-MS analysis of metabolites, and phytotoxicity assessment confirmed phytotransformation of RR into nontoxic metabolites. Floating phytobed with V. zizanioides treated textile wastewater (400 L) effectively and reduced ADMI, COD, BOD, TDS, and TSS by 74, 74, 81, 66 and 47%, respectively within 72 h. In-situ treatment of textile wastewater for 5 days in constructed furrows planted with semiaquatic plants, V. zizanioides, Ipomoea aquatica and its consortium-VI decreased ADMI by 68, 61 and 76%, COD by 75, 74 and 79%, BOD by 73, 71 and 84%, TDS by 77, 75 and 83%, and TSS by 34, 31 and 51%, respectively. This treatment was also useful to remove arsenic, cadmium, chromium and lead from wastewater. Overall observation suggests wise strategy to use this plantation in the furrows of high rate transpiration system and phytobeds in deep water for textile wastewater treatment.
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•Remazol Red, dye mixture and textile effluent treated efficiently by V. zizanioides.•Histological analysis confirmed entry and degradation of dyes in roots.•Floating phyto-bed reactor treated textile wastewater effectively.•Textile wastewater was noteworthily treated in plant cultivated furrows of HRTS.•Plant consortium enhanced the potential of textile dye removal.
This review article presents a comprehensive literature survey over the last two decades on the evaluation of production processes of succinic acid (SA) to further direct the research towards the ...membrane-based sustainable and economical production. The traditional chemical and petrochemical-based industries desperately need to switch from the conventional polluting and energy-intensive processes by the clean and green processes due to growing environmental concern, strict discharge limit and emaciated profit margin in a competitive world market. In recent years, the prospect for process intensification by the integration of highly selective customized membranes in an appropriate module with conventional fermenter for downstream separation, purification and concentration of SA seems imminent with the expectation of a turnaround in biochemical industries. Through a comprehensive literature survey of critical aspects, the review article has suggested a novel approach on the application of a multi-staged membrane-based system for the manufacturing of SA leading to the prospect of sustainable business.
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•State-of-art of succinic acid production reviewed.•Major drawbacks of traditional production processes evaluated.•New emerging technologies towards green processes highlighted.•Challenges and prospects of membrane-based succinic acid production assessed.•Membrane-based hybrid processes explored as potential and economical approach.
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•MOFs offer great opportunities in environmental remediation of different pollutants.•MOFs are potential adsorbents for water purification.•Strategies to improve the aqueous phase ...stability of MOFs are reviewed.•Performance of MOFs in aqueous phase emerging contaminants removal are highlighted.
Metal–organic frameworks (MOFs) have gained attention as promising materials for aqueous-phase sorptive removal of emerging contaminants (ECs). Attributes such as large adsorption capacity, high surface area, tunable porosity, hierarchical structure, and recyclability give MOFs an edge over conventional adsorbents. The poor stability of MOFs in water is a major challenge to their real-world environmental application. The performance of MOFs and their selectivity toward targeted pollutants for removal can be regulated by judicious selection of metal ion and organic linker. A range of water-stable MOFs (e.g., MIL-53, MIL-100, MIL-101, UiO-66, and MIL-125) and their composites with other materials have been reported to remove the ECs from water. The present review critically addressed the performance of MOFs for the adsorptive removal of different categories of ECs from water and the adsorption mechanisms involved. The performance of MOFs compared with other adsorbents has also been discussed. This body of rapidly developing research signifies the emerging importance of MOFs in environmental applications and provides a future direction for the development of treatment technology to effectively remove ECs from aqueous environments.
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•The addition of fats, oil and grease enhanced ultimate methane production by 217%.•Firmicutes, Bacteriodetes, Synergistetes and Euryarchaeota were greatly increased.•Dominance of ...Methanosaeta was replaced by Methanosarcina at the end of digestion.•Methane was predominantly generated through acetoclastic pathway by Methanosarcina.
Fats, oil and grease (FOG) are energy-dense wastes that substantially increase biomethane recovery. Shifts in the microbial community during anaerobic co-digestion of FOG was assessed to understand relationships between substrate digestion and microbial adaptations. Excessive addition of FOG inhibited the methanogenic activity during initial phase; however, it enhanced the ultimate methane production by 217% compared to the control. The dominance of Proteobacteria was decreased with a simultaneous increase in Firmicutes, Bacteriodetes, Synergistetes and Euryarchaeota during the co-digestion. A significant increase in Syntrophomonas (0.18–11%), Sporanaerobacter (0.14–6%) and Propionispira (0.02–19%) was observed during co-digestion, which substantiated their importance in acetogenesis. Among methanogenic Archaea, the dominance of Methanosaeta (94%) at the beginning of co-digestion was gradually replaced by Methanosarcina (0.52–95%). The absence/relatively low abundance of syntrophic acetate oxidizers and hydrogenotrophic methanogens, and dominance of acetoclastic methanogens suggested that methane generation during co-digestion of FOG was predominantly conducted through acetoclastic pathway led by Methanosarcina.
A new, simple, clean, and green procedure for the production of a magnetic nanocomposite (MBBC) from waste camel bone biochar was here described. MBBC particles were in the nano-size range (∼12 nm), ...having characteristics of both hydroxyapatite and magnetite. The produced nanocomposite was characterized by FT-IR, XRD, TG, SEM, TEM, BET, XRD, Zeta potential and XPS analyses. MBBC exhibited a paramagnetic behavior, having a saturation magnetization of 50.20 emu/g and a mesoporous structure with a BET surface area of 162 m2/g. The FT-IR spectrum of MBBC displayed doublet peaks at 573–601 cm−1 (corresponding to Fe–O vibrations) and a peak at 1046 cm−1 (associated with HPO4), which support the successful formation of MBBC. The maximum adsorption capacities of MBBC, as for the Langmuir isotherm model fittings, were 344.8, 322.6 and 294.1 mg/g for Pb(II), Cd(II) and Co(II), respectively. MBBC showed rapid heavy metals adsorption rates, accomplishing ∼75% adsorption within 5 min. After adsorption accomplishment, MBBC particles were magnetically separated from treated water and heavy metals from saturated MBBC were efficiently desorbed by elution with 0.01 M HCl. Under such elution, the MBBC stability against acid leaching of Fe was proved. Hence, it could be inferred that the production of MBBC from waste camel bones and its utilization for the removal of heavy metals from water is a novel approach within the cleaner production concept.
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•A magnetic nanocomposite (MBBC) was produced from waste camel bone biochar.•MBBC was ∼12 nm particle size, paramagnetic and mesoporous with 162 m2/g BET area.•Pb(II), Cd(II) and Co(II) adsorption capacities on MBBC were 345, 323 and 294 mg/g.•Metals recovery from saturated MBBC was maximum (85–90%) with 0.01 M HCl.•Deniable leaching of Fe occurred from MBBC during desorption with 0.01 M HCl.
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•Chlorella vulgaris was tolerant to levofloxacin, and could withstand its high doses.•96h EC50 of levofloxacin for C. vulgaris was 58.6mgL−1.•The acclimation of C. vulgaris enhanced ...the removal of levofloxacin.•Sodium chloride stimulated the biodegradation of levofloxacin up to 91%.•NaCl (1%w/v) increased the degradation rate constant (k) of LEV from 0.011 to 0.257d−1.
The extensive contamination of levofloxacin (LEV) in aquatic ecosystems has attracted increasing attention because of the potential for development of bacterial resistance and its eco-toxicity to non-target organisms. Biodegradation of LEV was significantly improved upon the acclimation of a freshwater microalga, Chlorella vulgaris and in the presence of elevated salinity. Among the six wild species (Chlamydomonas mexicana, Chlamydomonas pitschmannii, Chlorella vulgaris, Ourococcus multisporus, Micractinium resseri, Tribonema aequale), C. vulgaris showed the highest removal capacity (12%) of LEV at 1mgL−1. The acclimated C. vulgaris, which was pre-exposed to 200mgL−1 of LEV for 11days, exhibited enhanced removal of 1mgLEVL−1 by 16% after 11days of cultivation. The addition of 1% (w/v) sodium chloride into the microalgal media significantly improved LEV removal by >80% in the C. vulgaris culture. The bioaccumulation of LEV at day 11 in C. vulgaris cells without NaCl was 34μgg−1, which was elevated to 101μgg−1LEV at 1% NaCl. The bioconcentration factor for LEV was 34 and 1004 in 0 and 1% NaCl, respectively. The mass balance analysis of LEV showed that more than 90% of LEV was biodegraded by C. vulgaris at day 11 with the addition of 1% NaCl. These results demonstrated that the enhanced removal of LEV by salinity was mainly through bioaccumulation and subsequent intracellular biodegradation by C. vulgaris cells.
Rare earth elements (REEs) are essential raw materials for emerging renewable energy resources and ‘smart’ electronic devices. Global REE demand is slated to grow at an annual rate of 5% by 2020. ...This high growth rate will require a steady supply base of REEs in the long run. At present, China is responsible for 85% of global rare earth oxide (REO) production. To overcome this monopolistic supply situation, new strategies and investments are necessary to satisfy domestic supply demands. Concurrently, environmental, economic, and social problems arising from REE mining must be addressed. There is an urgent need to develop efficient REE recycling techniques from end-of-life products, technologies to minimize the amount of REEs required per unit device, and methods to recover them from fly ash or fossil fuel-burning wastes.
The increase in worldwide water contamination with numerous pharmaceutical contaminants (PCs) has become an emerging environmental concern due to their considerable ecotoxicities and associated ...health issues. Microalgae-mediated bioremediation of PCs has recently gained scientific attention, as microalgal bioremediation is a solar-power driven, ecologically comprehensive, and sustainable reclamation strategy. In this review, we comprehensively describe the current research on the possible roles and applications of microalgae for removing PCs from aqueous media. We summarize several novel approaches including constructing microbial consortia, acclimation, and cometabolism for enhanced removal of PCs by microalgae, which would improve practical feasibility of these technologies. Some novel concepts for degrading PCs using integrated processes and genetic modifications to realize algal-based bioremediation technologies are also recommended.
Water contamination with numerous pharmaceutical contaminants (PCs) has been one of the most important emerging environmental problems facing humanity due to their ecotoxicities and health issues.
Culturing microalgae in wastewater can create a ‘zero-waste concept’ and stimulate an effective and sustainable practice for the microalgae biofuel industry.
Constructing microbial consortia, acclimating microorganisms, and cometabolic approaches can improve the engineering feasibility of microalgae-based biotechnologies.
Some innovative concepts, such as integrated processes (algae-based technologies with advanced oxidation processes, constructed wetlands, and microbial fuel cells) and genetic modifications, can help to realize algae-based bioremediation technologies.
•Methane productivity of unacclimatized and acclimatized sludge were investigated.•Biogas produced in ASS showed higher methane content (65–76%) than in USS (26–73%).•The ASS exhibited greater ...degradation of LCFAs than in USS.•Firmicutes, Bacteroidetes, Synergistetes and Euryarchaeota were highly increased.•Abundance of Syntrophomonas and Methanosarcina in ASS improved methane generation.
The methane productivity and long chain fatty acids (LCFAs) degradation capability of unacclimatized seed sludge (USS) and acclimatized seed sludge (ASS) at different substrate ratios of fats oil and grease (FOG) and mixed sewage sludge were investigated in this study. Biogas produced in ASS in initial phase of anaerobic digestion had higher methane content (65–76%) than that in USS (26–73%). The degradation of major LCFAs in the ASS was 22–80%, 33–191%, and 7–64% higher for the substrate ratios of 100:10, 100:20, and 100:30, respectively, as compared to the LCFAs’ degradation in USS. Microbial acclimatization increased the population of Firmicutes (40%), Bacteroidetes (32%), Synergistetes (10%), and Euryarchaeota (8%) in ASS, which supported the faster rate of LCFAs degradation for its later conversion to methane. The significant abundance of Syntrophomonas and Methanosarcina genera in ASS supported faster generation rate of methane in an obligatory syntrophic relationship.
•Challenges in biomethane production from anaerobic co-digestion of FOG.•Pretreatment of FOG for improved anaerobic co-digestion.•Metagenomics of population dynamics and interspecies ...interactions.•Process optimization for FOG co-digestion.•Operation of commercial plants and economic feasibility of FOG co-digestion.
Anaerobic digestion (AD) of wastewater sludge is an effective approach to produce biomethane and subsequently reduce the amount of sludge disposal to landfill generated from wastewater treatment plants (WWTPs). Recently, anaerobic co-digestion (ACD) of lipidic-waste such as fat, oil, and grease (FOG) has received much attention for the enhancement of biomethanation in WWTPs. However, there are several major challenges associated with ACD of FOG which includes inhibition by long chain fatty acids, sludge floatation and washout, and scum formation. This review summarizes the scientific and engineering aspects of the FOG supplementation as a co-substrate in AD as well provides appropriate solutions for challenges encountered during the anaerobic operation. The discussion on the existing pretreatment approaches (including mechanical, thermo-chemical, and biological) for rapid degradation of FOG was also highlighted. Metagenomic analysis elucidates the microbial community and the interspecies interactions which are responsible for the degradation of FOG and its biomethanation during ACD. Addition of FOG to AD was found be economically feasible in municipal WWTPs.
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