American Dye Manufacturers Institute Research Articles

Fiberglass cloth coated by coffee ground waste-derived carbon quantum dots/titanium dioxide composite for removal of caffeine and other pharmaceuticals from water

Coffee ground waste from the coffee beverage preparation is mainly discarded and consequently ends up in landfill, which cause the contamination of caffeine in various environmental compartments. This study focuses on the upcycling of coffee-ground waste to carbon quantum dots (CQDs) for use as a modifying material to improve the visible light activity of titanium dioxide (TiO2). The CQD solution was synthesized by hydrothermal method, which has an average size of 2.80 ± 0.63 nm. The CQDs/TiO2 photocatalysts were prepared by combining CQD solutions at various amounts with sol-gel TiO2 and then coated on the fiberglass cloths (FGCs). The photocatalytic application mainly focuses on the removal of caffeine from the water. The photocatalytic experiment was preliminary run in a simple batch reactor under visible light. The 5CQDs/TiO2 coated FGC (5 mL of CQD solution/g of Ti-based on sol-gel) showed the best performance, and it was selected for the removal of caffeine and other pharmaceuticals (i.e., carbamazepine and ibuprofen) in the recirculating reactor. The removals of caffeine, carbamazepine, and ibuprofen after irradiation for 9 h were 82%, 88%, and 84%, respectively. The residual concentrations were significantly lower than the reported toxicity levels based on specific species. The changes in total organic carbon were observed, indicating the mineralization of pharmaceuticals in water. The 5CQDs/TiO2 coated FGC showed good flexible performance. No obvious loss of activity was observed for five runs. The actual wastewater from the coffee pot cleaning process was also tested. The removal was 80% for caffeine and 86% for color in the unit of the American Dye Manufacturers Institute (ADMI).

Synergistic decolorization and detoxication of reactive dye Navy Blue 250 (NB250) and dye wastewater by the UV/Chlorine process

The research aims for the simultaneous use of chlorine and UV irradiation (UV/Chlorine) to decolorize and detoxify Navy Blue 250 (NB250) and raw dye wastewater. The UV/Chlorine was the most effective in removing NB250 and color intensity (American Dye Manufacturers Institute, ADMI unit). The UV/Chlorine removed NB250 approximately 1.47–1.50 times faster than chlorination alone. The degradation constants in UV/Chlorine were 0.3317 mM-1min-1 and 0.3384 mM-1min-1 for NB250 and its ADMI color intensity, respectively. The optimum pH for decolorization was between 6 and 7. The UV/Chlorine with a chlorine dose of 1.0–2.0 mM was recommended for decolorization to meet the industrial discharge standard (300 ADMI). Reactive chlorine species (RCS) were more significant oxidants for NB250 removal than HO•. The presence of NB250 inhibited the germination of morning glory (Ipomoea aquatica) seeds, and exposure to raw dye wastewater (color = 6,658 ± 227 ADMI) completely inhibited seed germination. However, the samples treated by the UV/Chlorine were less toxic to seed germination and root growth. Therefore, the UV/Chlorine has a high potential in the decolorization and detoxification of dye wastewater. This is the first study to use the UV/Chlorine to treat industrial dye wastewater.

Optimization of operational parameters in air-gap membrane distillation using central composite design applied in recovery of dye manufacturing wastewaters

ABSTRACT The challenge for water recovery from dye manufacturing wastewaters that contain high salinity and high dye concentration is recovery efficiency and water quality. The permeate flux and water quality mainly reflect the membrane distillation performance in treatments of these wastewaters. This study investigated the effects of Air Gap Membrane Distillation’s (AGMD) operational parameters and its interactions on permeate fluxes and recovered water quality in treatments of real dye manufacturing wastewaters using design of experiments (DOE). The DOE method used the response surface methodology (RSM) of central composite design (CCD) to predict and optimize the permeate flux and recovered water quality. The results showed a reliable predictive model of actual permeate flux (15.5 kg.m−2.h−1) with the adjusted R2 adj of 0.995 and only 34.4%–73.8% of the theoretical permeate flux because of salt contents’ main effect. The rejection rate of chloride ion (Cl−), sulfate ion (SO4 2-), and ADMI (American Dye Manufacturers’ Institute) color index from real dye manufacturing wastewaters with high salinity was more than 99,9%. The COD removal rate of raw wastewater (C1) from dye manufacturing was 99,4%. This study help in understanding theoretical and actual membrane flux and the scale-up of a membrane treatment plant.

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

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

Treatment of Textile Dye Wastewater using Cynobacteria Spirulina Sp

Along with toxic dyes textile dye wastewater contains various xenobiotic compounds therefore their treatment is necessary before discharging into the environment. Bioremediation was considered as one of the eco-friendly and self-sustainable treatment systems and amongst them cyanobacteria was considered as one of the best resources for the bioremediation of organic pollutants. Thus, in this present study, Spirulina sp. was evaluated for the treatment of real textile dye wastewater (RTDW) along with the removal of metal ions and other organic pollutants. The metabolic activities to Spirulina sp. leads to complete more than 98% decolorization of Reactive Brown GR11, Reactive Magenta HBB 26, Reactive Red Bs11 and Reactive Yellow 160 dye. However, to enhance the treatment efficiency of Spirulina sp. carbon and nitrogen sources were optimized. In the presence of 1% glucose and yeast extract Spirulina sp. showed 86% American Dye Manufacturers’ Institute (ADMI) removal and 83 % chemical oxygen demand (COD) reduction from the undiluted non-sterilize RTDW. The maximum treatment efficiency of Spirulina sp. was observed at pH-7 and 30 °C under optimized co-substrates. Degradation of RTDW and representative four azo dyes were further confirmed by using ultraviolet–visible spectrophotometry (UV–vis), High Performance Liquid Chromatography (HPLC), and Fourier- transform infrared spectroscopy (FTIR) analysis. Additionally, toxicity analysis was considered as the best method to evaluate the efficiency of treatment process. Phytotoxicity and cytotoxicity assay clearly show that Spirulina sp. treatment significantly reduces the toxic characteristics of RTDW.

Electroactive bacterial community augmentation enhances the performance of a pilot scale constructed wetland microbial fuel cell for treatment of textile dye wastewater

This study evaluated the effect of bioaugmentation of a newly enriched electroactive bacterial community DC5 on the performance of a pilot scale sequential two-step Horizontal Sub-surface flow Constructed Wetland-Microbial Fuel Cell (HSCW-MFC) system treating textile dye wastewater. The system consisted of CW-MFC-1 planted with Fimbristylis ferruginea and CW-MFC-2 planted with consortium of Fimbristylis ferruginea and Elymus repens plant species. Before bioaugmentation, HSCW-MFC system showed 62 ± 2% Chemical Oxygen Demand (COD) and 90 ± 1.5% American Dye Manufacturer's Institute (ADMI) removal and 177.3 mW/m2 maximum power density (CW-MFC-1). After bioaugmentation of DC5 into the HSCW-MFC, COD and ADMI removal was enhanced to 74.10 ± 1.75% and 97.32 ± 1.90% with maximum power density of 197.94 mW/m2 (CW-MFC-1). The genera Exiguobacterium, Desulfovibrio and Macellibacteroides of DC5 were significantly enriched at the electrodes of HSCW-MFC after bioaugmentation. These results demonstrate that the performance of the CW-MFC treating textile dye wastewater can be improved by bioaugmentation of electroactive bacterial community.

Bioremediation of cardboard recycling industry effluents using mixed fungal culture

PurposeThis paper aims to evaluate the bioremediation [chemical oxygen demand (COD) and color removal] of the effluent from the cardboard recycling industry in Yazd, central province of Iran, using mixed fungal culture.Design/methodology/approachFirst, the effluent samples from the cardboard recycling industry were cultured on potato dextrose agar medium to isolate native fungal colonies. The grown colonies were then identified using morphological macroscopic and microscopic characteristics to choose the dominant fungi for bioremediations. The mixed cultures of Aspergillus niger, Aspergillus flavus and Penicillium digitatum were finally used for bioremediation experiments of the cardboard recycling industry. A suspension containing 1 × 106 CFU/ml of fungal spores was prepared from each fungus, separately and their homogenous mixture. Sewage samples were prepared and sterilized and used at 25%, 50% and 90% dilutions and pH levels of 5, 7 and 8 for bioremediation tests using mixed fungal spores. Following that, 10 ml of the mixed fungal spores were inoculated into the samples for decolorization and COD removal and incubated for 10 days at 30°C. The amount of COD removal and decolorization were measured before incubation and after 3, 6 and 10 days of inoculation. In this research, the color was measured by American Dye Manufacturer Institute and COD by the closed reflux method. The results of the present study were analyzed using SPSS 21 statistical software and one-way ANOVA tests at p-value < 0.05.FindingsThe results of this research showed that the mean decolorization by mixed fungal culture over 10 days at pH levels of 5, 7 and 8 were 44.40%, 45.00% and 36.84%, respectively, and the mean COD removal efficiency was 71.59%, 73.54% and 16.55%, respectively. Moreover, the mean decolorization at dilutions of 25%, 50% and 90% were 45.00%, 31.93% and 30.53%, respectively, and the mean COD removal efficiency was 73.54%, 62.38% and 34.93%, respectively. Therefore, the maximal COD removal and decolorization efficiency was obtained at dilution of 25% and pH 7.Originality/valueGiven that limited studies have been conducted on bioremediation of the effluent from the cardboard recycling industry using fungal species, this research could provide useful information on the physicochemical properties of the effluent in this industry.

Performance and biofilm-associated bacterial community dynamics of an upflow fixed-film microaerophilic-aerobic bioreactor system treating raw textile effluent

Textile wastewater contains numerous xenobiotic compounds which have several detrimental effects on aquatic and terrestrial ecosystems. Therefore, the adequate treatment of textile wastewater is essential. This study elucidated the biodegradation of raw textile effluent (RTE) in an upflow fixed-film microaerophilic bioreactor (UFMB) along with the characterization of its bacterial community dynamics at different hydraulic retention times (HRTs) and organic loading rates (OLRs). Among the various packing materials tested in the UFMB operation, wood charcoal was found to be the most suitable packing material for the establishment of biofilm and biodegradation of RTE. The steady-state performance of UFMB having wood charcoal as packing material achieved 81.97% of American dye manufacturers institute (ADMI) colour index removal, 73.08% of biochemical oxygen demand (BOD) removal and 80.47% of chemical oxygen demand (COD) removal at 2d HRT. Whereas, upon integration of the UFMB with the sequential aerobic bioreactor (UFMB-AB system), achieved better performances with 98.6% COD, 98% ADMI and 92% BOD removal from the RTE. Additionally, the combined UFMB-AB system effectively removed other contaminants such as sulphate, phenolics and nitrogenous compounds in the RTE. The biofilm was synergistically established by the bacterial community DR4 and the native community of RTE. In response to different HRTs and OLRs, the UFMB bacterial biofilm community experienced various shifts in its composition. However, a core microbiome persisted throughout the bioreactor operation. The imputed metagenome analysis of the established UFMB biofilm using phylogenetic investigation of communities by unobserved state reconstruction (PICRUSt), revealed the presence of several xenobiotic degradation and metabolism pathways with an abundance of various different oxidoreductase genes responsible for the biodegradation of dyes and other organic pollutants present in the RTE.

Study of simultaneous bioremediation of mixed reactive dyes and Cr(VI) containing wastewater through designed experiments.

Xenobiotic azo dyes and chromate (Cr(VI)) containing industrial wastewaters cause severe ecological problems. The present bioremediation study aims to treat wastewater containing Cr(VI) ions and mixed azo dyes (reactive red 21 (RR21) and reactive orange 16 (RO16)) by Pseudomonas aeruginosa 23N1. The process optimization of bioremediation is investigated using statistical designed experimental tool of response surface methodology. The ANOVA analysis is performed to evaluate optimal biodecolourization condition. This study shows that the amount of yeast extract has major influence on biodecolourization performance. The decolourization of individual RO16 and RR21 dye in presence of 60mg/L of Cr(VI) ions is obtained as 88.5 ± 0.8 and 92.3 ± 0.7% for 100 and 150mg/L initial dye concentrations, respectively. In this study, bacteria exhibit high Cr(VI) removal potential of ~99.1% against initial Cr(VI) concentration of 150mg/L. The negative influence of Cr(VI) ions on biodecolourization is only noticed when initial Cr(VI) concentration in wastewater is found above 150mg/L. The results reveal that bacteria studied here could be used to biodecolourize dyes even in high saline condition (> 6000mg/L). The reduction of ~ 80% in American Dye Manufacturers Institute colour index value is achieved for mixed dyes solution containing 50mg/L of both RR21 and RO16 dyes along with 50mg/L Cr(VI) ions. Significant changes in the UV-visible and ATR-FTIR spectra are observed in treated water that confirms the biodegradation of dyes. Toxicity study with Vigna radiata reveals the non-toxicity of degraded metabolites and strain 23N1 is recommended as an effective bioremediation agent.

Microaerophilic biodegradation of raw textile effluent by synergistic activity of bacterial community DR4

Treatment of raw textile effluent (RTE) is very difficult, due to its inherent heterogeneous, low-biodegradable and toxic compositions. Pure and mixed microbial cultures have limited metabolic capabilities in effective mineralization of complex RTE. Therefore, in this study a novel bacterial community DR4 was enriched directly into a complex RTE consisting of 27 different dyes using textile dye polluted soil as an inoculum. The rigorous enrichment process resulted in acclimatization of a taxonomically distinct bacterial population, with an abundance of the genus Comamonas in the bacterial community DR4 as compared to the abundance of Pseudomonas in the RTE respectively, as revealed by high-throughput 16S rRNA gene (V3–V4 region) sequencing. Microaerophilic treatment of RTE by enriched bacterial community DR4, in the presence of optimized electron donor (sucrose) and nitrogen source (yeast extract) resulted in 88% of American Dye Manufacturer's Institute (ADMI) removal and 98% of Chemical oxygen demand (COD) reduction within 32 h at 37 °C. In silico prediction of the functional genes within bacterial community DR4 was made by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. The PICRUSt analysis revealed high abundance of xenobiotic degradation and metabolism genes. The predicted functional genes and textile dye degradation pathways were further validated using Ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared (FTIR) spectroscopy and High Resolution Liquid Chromatography coupled with Mass Spectrometry (HR-LCMS) based characterization of textile dye degradation metabolites. The activity of azoreductases in the cell-free extracts (CFE) of the enriched bacterial community DR4 was induced by 1.83–7.81 folds in the presence of representative textile dyes as compared to uninduced samples, which confirmed their role in textile effluent decolourization. The degradation of four representative azo dyes present in RTE such as Disperse orange 30, Reactive red 152, Direct blue 2 and Acid brown 15 depicted symmetric degradation of azo bonds by bacterial community DR4.

Prospective Application of Palm Oil Mill Boiler Ash as a Biosorbent: Effect of Microwave Irradiation and Palm Oil Mill Effluent Decolorization by Adsorption.

Common conventional biological treatment methods fail to decolorize palm oil mill effluent (POME). The present study focused on using the abundant palm oil mill boiler (POMB) ashes for POME decolorization. The POMB ashes were subjected to microwave irradiation and chemical treatment using H2SO4. The resultant adsorbents were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analyses. The adsorption efficiency was evaluated at various pH levels (2–8.5), adsorption dosages (3–15 g) in 200 mL, and contact times (1–5 h). The microwave-irradiated POMB-retained ash recorded the highest color removal of 92.31%, for which the best conditions were pH 2, 15 g adsorbent dosage in 200 mL, and 5 h of contact time. At these best treatment conditions, the color concentration of the treated effluent was analyzed using the method proposed by the American Dye Manufacturers Institute (ADMI). The color concentration was 19.20 ADMI, which complies with the Malaysia discharge standard class A. The Freundlich isotherm model better fit the experimental data and had a high R2 of 0.9740. Based on these results, it can be deduced that microwave-irradiated POMB-retained ash has potential applications for POME decolorization via a biosorption process.

Application of a downflow microaerophilic fixed film (DFMFF) reactor for the treatment of dye house effluents using a developed bacterial consortium

The present study describes a downflow microaerophilic fixed film (DFMFF) reactor based treatment of dye house effluents. The major characteristics of the two effluents E-2 and E-5 under study were; chemical oxygen demand (COD) 4680-16,266 mg L−1, biological oxygen demand (BOD) 1575–3151 mg L−1 and American Dye Manufacturers' Institute (ADMI) color index of 10,794–21,413. DFMFF reactor was packed with ultra-high molecular weight polyethylene (UHMWPE) shredding. The developed consortium was allowed to grow and form bio-film on packed UHMWPE. Degradation of the effluents at a various hydraulic retention time (HRT) and organic loading rate (OLR) was studied. Batch mode studies in the reactor showed > 80% removal of BOD and COD at OLR of 4.3 kg L−1 day−1 of E-2 and 2.4 kg L−1 day−1 of E-5 at 48 h HRT. Fourier Transform Infrared Spectroscopy (FTIR) and High Performance Liquid Chromatography (HPLC) analysis confirmed biodegradation and obtained results indicated significant induction of oxidoreductive enzyme activities of azoreductase, NADH–DCIP reductase and laccase enzymes. Reduction in phytotoxicity and microbial toxicity was observed after the treatment of both the effluents. The reactor was also operated on continuous mode for treatment of E-2 under sequential anaerobic–aerobic phase and charcoal treatment. Results of sequential effluent treatment resulted in a reduction of > 99% of COD, BOD and ADMI along with > 88% of solids removal from the effluent. The resulting effluent was clear and meets the discharge criteria so as to release into the sewers. .

In situ phytoremediation of dyes from textile wastewater using garden ornamental plants, effect on soil quality and plant growth

In situ phytoremediation of dyes from textile wastewater was carried out in a high rate transpiration system ridges (91.4 m × 1.0 m) cultivated independently with Tagetes patula, Aster amellus, Portulaca grandiflora and Gaillardia grandiflora which reduced American Dye Manufacturers Institute color value by 59, 50, 46 and 73%, respectively within 30 d compared to dye accumulated in unplanted ridges. Significant increase in microbial count and electric conductivity of soil was observed during phytoremediation. Reduction in the contents of macro (N, P, K and C), micro (B, Cu, Fe and Mn) elements and heavy metals (Cd, As, Pb and Cr) was observed in the soil from planted ridges due to phyto-treatment. Root tissues of these plants showed significant increase in the specific activities of oxido-reductive enzymes such as lignin peroxidase, laccase, veratryl alcohol oxidase, tyrosinase and azo reductase during decolorization of textile dyes from soil. Anatomical studies of plants roots revealed the occurrence of textile dyes in tissues and subsequent degradation. A minor decrease in plant growth was also observed. Overall surveillance suggests that the use of garden ornamental plants on the ridges of constructed wetland for the treatment of dyes from wastewater along with the consortia of soil microbial flora is a wise and aesthetically pleasant strategy.

Photocatalytic activity of CuO/Cu(OH)2 nanostructures in the degradation of Reactive Green 19A and textile effluent, phytotoxicity studies and their biogenic properties (antibacterial and anticancer)

In this study, CuO/Cu(OH)2 (denoted as CuONs) nanostructures were synthesized relying to a cheap and rapid chemical co-precipitation method using copper sulfate and liquid ammonia as precursors. Results obtained from X-ray diffraction, and field emission scanning electron microscopy analysis revealed the crystalline nature of synthesized CuONs. Fourier transform infrared spectroscopy and energy dispersive spectroscopy studies showed interactions between copper and oxygen atoms. Synthesized CuONs showed the size in the range of 20–30 nm using high resolution transmission electron microscopy analysis. The photocatalytic degradation performance of Reactive Green 19A (RG19A) dye using CuONs was evaluated. The results showed that CuONs exhibited 98% degradation efficiency after 12 h and also complete mineralization in form of reducing chemical oxygen demand (COD) (84%) and total organic carbon (TOC) (80%). The nanocatalyst was recovered from the dye containing solution and its catalytic activity can be reused up to four times efficiently. CuONs was also able to decolorize actual textile effluent (80% in terms of the American Dye Manufacturers' Institute (ADMI) value) with significant reductions in COD (72%) and TOC (69%). Phytotoxicity studies revealed that the degradation products of RG19A and textile effluent were scarcely toxic in nature, thereby increasing the applicability of CuONs for the treatment of textile wastewater. Additionally, the CuONs showed a maximum antibacterial effect against human pathogens which also displayed synergistic antibacterial potential related to commercial antibiotics. Moreover, CuONs displayed strong antioxidant activity in terms of ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (IC50: 51 μg/mL) and DPPH (1,1-diphenyl-2-picrylhydrazyl) (IC50: 60 μg/mL) radical scavenging. The CuONs exhibited dose dependent response against tumor rat C6 cell line (IC50: 60 μg/mL) and may serve as anticancer agents.

Exploring the potential of fungal-bacterial consortium for low-cost biodegradation and detoxification of textile effluent

AbstractIn the present study, the enrichment and isolation of textile effluent decolorizing bacteria were carried out in wheat bran (WB) medium. The isolated bacterium Providencia rettgeri strain HSL1 was then tested for decolorization of textile effluent in consortium with a dyestuff degrading fungus Aspergillus ochraceus NCIM 1146. Decolorization study suggests that A. ochraceus NCIM 1146 and P. rettgeri strain HSL1 alone re moves only 6 and 32% of textile effluent American Dye Manufacturing Institute respectively in 30 h at 30 ±0.2°C of microaerophilic incubation, while the fungal-bacterial consortium does 92% ADMI removal within the same time period. The fungal-bacterial consortium exhibited enhanced decolorization rate due to the induction in activities of catalytic enzymes laccase (196%), lignin peroxidase (77%), azoreductase (80%) and NADH-DCIP reductase (84%). The HPLC analysis confirmed the biodegradation of textile effluent into various metabolites. Detoxification studies of textile effluent before and after treatment with fungal-bacterial consortium revealed reduced toxicity of degradation metabolites. The efficient degradation and detoxification by fungal-bacterial consortium pre-grown in agricultural based medium thus suggest a promising approach in designing low-cost treatment technologies for textile effluent.

Moringa oleifera-mediated coagulation of textile wastewater and its biodegradation using novel consortium-BBA grown on agricultural waste substratum.

Generation of secondary sludge is a major concern of textile dye removal by coagulation process. Combinatorial coagulation-biodegradation treatment system has been found efficient in degradation of coagulated textile dye sludge. Moringa oleifera seed powder (700mgL-1) was able to coagulate textile dyestuff from real textile wastewater with 98% color removal. Novel consortium-BBA was found to decolorize coagulated dye sludge. Parameters that significantly affect coagulation process were optimized using response surface methodology. The bench-scale stirred tank reactor (50-L capacity) designed with optimized parameters for coagulation process could efficiently remove 98, 89, 78, and 67% of American Dye Manufacturer's Institute (ADMI) in four repetitive cycles, respectively. Solid-state fermentation composting reactor designed to treat coagulated dye sludge showed 96% removal of dye within 10days. Coagulation of dyes from textile wastewater and degradation of coagulated dye sludge were confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. Cell morphology assay, comet assay, and phytotoxicity confirmed the formation of less toxic products after coagulation and degradation mechanism.

Biotransformation of mixture of dyes by enriched bacterial consortium ASD

AbstractDye effluents released from textile industries has gradually entrenched the roots of peril to majority of the water bodies. Considering the alarming need of innovative bioremediation technologies, the present study aims to evaluate the biodegradation potential of a bacterial consortium ASD for mineralization of a mixture of structurally different dyes. Consortium ASD, developed from dye contaminated soil from Vatva industrial estate, constitutes of four bacterial strains viz. Pseudomonas sp., Brevibacillus sp. and two strains of Stenotrophomonas sp. The intense metabolic activity of these strains together, led to 94% ADMI removal (American dye Manufacturers Institute) of 100 mg l−1 of a mixture of dyes in the presence of starch (0.1%, w/v) and proteose peptone (0.4%, w/v) within 24 h at 37°C under static (microaerophilic) condition and could tolerate up to 400 mg l−1 of dye mixture. Consortium was also able to reduce total organic carbon and chemical oxygen demand by 85 and 78% within 24 h. Signif...

Glutaraldehyde cross-linked magnetic chitosan nanocomposites: Reduction precipitation synthesis, characterization, and application for removal of hazardous textile dyes

Magnetic chitosan nanocomposites (MCNCs) were synthesized by an inexpensive reduction precipitation technique using a glutaraldehyde cross-linking agent at room temperature. Successful chitosan coating of iron oxide nanoparticles was confirmed by X-ray photoemission spectroscopy. X-ray diffraction data revealed crystalline particle sizes for the iron oxide and MCNCs to be around 6–7 and 8–9nm, respectively. In addition, the MCNCs exhibited supermagnetic properties having magnetic saturation of 17.5emu/g. The synthesized MCNCs showed 91.60% absorption of Acid Red 2, while iron oxide 16.40% absorption; enhanced performance in MCNCs was resulted from presence of free amino and hydroxyl groups. Furthermore, the optimum pH and adsorbent concentration were 3 and 1.0g/L, respectively. The Redlich–Peterson isotherm fit experimental data better than Langmuir and Freundlich models, based on non-linear regression. Finally, MCNCs showed 96% American Dye Manufacturing Institute (ADMI) value removal and gave recovery efficiency of 100%, making them attractive for further practical applications.

Enhancing biological treatment of dye wastewater with zero-valent iron

Pretreatment of authentic industrial dye wastewater with zero-valent iron (ZVI) was evaluated using a bench-scale integrated anaerobic-aerobic (ZVI-AO) biological treatment system. Average ADMI (American Dye Manufacturers’ Institute) value of dye wastewater was reduced from 245 to 107 units with ZVI column pretreatment. Subsequent treatment of ZVI column effluent by a continuous AO process further reduced the ADMI values to 18-39, resulting in overall decolorization efficiency of 78-89%. A control AO system without ZVI pretreatment, which was operated in parallel, achieved just 44-69% of ADMI removal efficiency. In addition, the ZVI integrated system yielded effluents with much lower COD and BOD concentrations than the control system. The aerobic batch respiration tests confirmed that ZVI treatment transformed the recalcitrant dye compounds to slowly biodegradable fractions, thus enhancing the overall biodegradability of dye wastewater.

Zinc chloride as a coagulant for textile dyes and treatment of generated dye sludge under the solid state fermentation: Hybrid treatment strategy

Dye sludge generation is major drawback of coagulation process. Efficient hybrid technology by combining coagulation and solid state fermentation (SSF) has capacity to solve generated dye sludge problem. Coagulation of 100mg/L Reactive Red 120 (RR120) using ZnCl2 showed 99% color removal. Mixture of textile dyes (MTD) and textile wastewater (TW) showed 96% and 98% ADMI (American Dye Manufacturing Institute) removal after coagulation by ZnCl2. 92% and 94% ADMI removal from MTD and TW dye sludge and 96% decolorization of RR120 sludge was observed respectively by developed microbial consortium (DCM) in 72h under SSF. Scale up of coagulation process by coagulation reactor (CR) having 50L capacity operated for 30min/cycle. CR showed average 94% ADMI removal from TW in 10 successive cycles. Scale up of SSF composting bioreactor (CB) showed complete dye removal from dye sludge obtained from CR (500L of TW) in 30days.