Simulated Effluent Research Articles

Application of seed residues from Anadenanthera macrocarpa and Cedrela fissilis as alternative adsorbents for remarkable removal of methylene blue dye in aqueous solutions.

Two novel ecological and low-cost adsorbents were prepared from seed residues of the tree species Anadenanthera macrocarpa and Cedrela fissilis for the removal of methylene blue dye in water. The materials were comminuted and characterized by different techniques. The particles of samples have a rough surface with cavities. The optimum dosage and pH for both materials were 1 g L-1 and pH 8. The pseudo-second-order model was the most suitable for describing the adsorption kinetics for both systems. The Anadenanthera macrocarpa presented a maximum experimental capacity of 228 mg g-1, while the Cedrela fissilis, a similar capacity of 230 mg g-1 at 328 K. The Tóth model was proper for describing the equilibrium curves for both systems. The thermodynamic indicators show that the adsorption process is spontaneous and endothermic for both materials. The application of materials for the simulated effluent treatment showed 74 and 78% of color removal using Anadenanthera macrocarpa and Cedrela fissilis samples, respectively. Overall, seed residues of Anadenanthera macrocarpa and Cedrela fissilis could be potentially applied for adsorptive removal of colored contaminants in wastewater.

Evaluating metabolic potential of Thauera sp. M9 for the transformation of 4-chloroaniline (4-CA)

Abstract Thauera sp. M9, was isolated after enrichment of microbial diversity in nitrogen free mineral salt medium (NFMSM) supplemented with 300 mg/l of 4-chloroaniline (4-CA). The isolate M9 was able to achieve complete degradation of 300 mg/l 4-CA supplement to NFMSM, after 30 h incubation. In addition to 4-CA, isolate M9 was able to achieve complete degradation of 300 mg/l 3-chloroaniline (3-CA), 21% degradation of 300 mg/l 2-chloroaniline (2-CA), and complete transformation of 50 mg/l of 3, 4-dichloroaniline (3, 4-DCA), was observed only in the presence of 0.02% (w/v) yeast extract (YE) supplement to NFMSM. The presence of catechol 2, 3-dioxygenase (C23O) activity in cell free extract and detection of 4-chlorocatechol (4-CC); 2-hydroxy muconic semialdehyde (2-HMS) in biologically transformed samples by mass spectroscopy (MS) analysis indicated to meta-cleavage of the aromatic ring. A plug flow reactor (PFR) was developed using polyurethane foam (PUF) and refractory brick pieces (RBP) as immobilization matrix. The treatment of simulated effluent supplemented with 300 mg/l 4-CA through PFR, resulted in 88% transformation of 4-CA and 70% lowering of chemical oxygen demand (COD). These observations suggest that Thauera sp. M9 could be a potential inoculum for developing bioremediation protocols for waste rich in chloroanilines (CAs).

Nitrate removal by electrocoagulation process using experimental design methodology: A techno-economic optimization

The aim of this study was to evaluate nitrate removal from simulated effluent by electrocoagulation (EC) process using experimental designs methodology (EDM). Plackett-Burman design (PBD) was firstly used for screening of five factors, such as current intensity (0.5–2 A), treatment time (20−60 min), initial effluent pH (4–10), electrode type (Fe, Al) and electrolyte type (Na2SO4, NaCl), on nitrate removal. Respective contributions of factors were 41.56 %, 26.51 %, 7.04 %, 23.98 % and 0.91 %. Results showed also that high current intensity, high electrolysis time, low initial pH as well as the use of aluminum electrodes, are favorable to high nitrate removal. Then, Box-Behnken design (BBD) was used to optimize nitrate removal while minimizing ammonium generated and operating cost. The optimal conditions obtained are the following: intensity 1.80 A, time 33.0 min and pH 8.73. Under these conditions, 73.8 % of nitrate were eliminated against 12.02 mg/L of ammonium and 1.8 g of metallic residues generated for an operating cost of 1.3 $ US/m3. Based on these results, EC can be considered as an efficiency process for nitrate removal. Also, it was found that BBD could be a reliable statistical tool to model the process and to determine the optimal conditions in terms of cost-effectiveness.

MATHEMATICAL MODELING OF AN AIRLIFT FLOTATION COLUMN WITH DIFFERENT GEOMETRIES FOR WATER AND OIL SEPARATION

Petroleum is one of the top commodities in the world, which produces some of the most environmentally hazardous wastes, such as produced water. Thus, research on technologies capable of processing wastewater are important for promoting the treatment of this waste and reducing costs in the segment. Among the processes used to treat wastewater, flotation is one of the leading methods used in physical separation operations. The efficiency of this technique has a high influence on internal hydrodynamic flows. This paper proposes a mathematical modeling to fluid dynamics of oil-water separation in an airlift flotation column based on momentum and continuity balance equations. To simplify the modeling used, we considered only the drag force as the most relevant interfacial force in this phenomenon. The software Ansys CFX 13.0 was used to evaluate the data. Three columns were created, and all data were submitted to a simulated effluent, containing 1000 ppm of oil. By evaluating efficiency selection in three columns and observing the countercurrent design, we found 84.72% as the best result achieved. This result can be associated with a column model that allows better phase contact as an ideal turbulence in the recirculation zone. Despite the simplifications in the proposed model, it is possible to observe a good association between the results obtained in the simulations and the ones presented in the literature.

Chemical modification of tannins from Acacia mearnsii to produce formaldehyde free flocculant

Flocculants and coagulants market is expected to grow in a Compound Annual Growth Rate (CAGR) of 5.9% between 2017 and 2022. The development of non-pollutant coagulants/flocculants aiming to replace conventional ones, usually toxic, has been extensively studied and one alternative is the possibility of obtaining tannin-based flocculants, compounds present in many plants and easily extracted. However, in order to use tannins as flocculants, their cationization is necessary, which is normally accomplished by Mannich reaction that requires formaldehyde addition, a toxic compound. In order to fill a gap in the literature, regarding coagulants/flocculants synthesis through green procedures, this paper aims to synthesize a flocculant from tannins with no use of formaldehyde, and optimize this synthesis through a Central Composite Rotatable Design (CCRD). The optimization variables were ammonium hydroxide (NH4OH) to tannin ratio, in the range of 1:1 to 5:1, and reaction time, in the range of 1 to 4 h The evaluation of the synthesized flocculant samples was accomplished by jar tests using a simulated effluent containing humic acid and the effect of reactant ratio and reaction time used in the synthesis was assessed. The flocculant synthesis methodology proposed on this study showed excellent results regarding turbidity and color removal, since 100% of turbidity removal and 89.9% of color removal were achieved. This novel tannin-based flocculant synthesis methodology is a promising technology to replace conventional coagulants/flocculants, once it is environmentally friendly.

Bioremediation of Simulated Textile Effluent by an Efficient Bio-catalyst Purified from a Novel Pseudomonas fluorescence LiP-RL5

Background: Microbial degradation of highly stable textile dyes, using lignin peroxidase, is an eco-friendly, less expensive and much advantageous in comparison to the chemical method. Objective: Biodegradation potential of lignin peroxidase (LiP), from Pseudomonas fluorescens LiP-RL5, was enhanced after optimization and purification so as to use it as a potential bioresource for the treatment of textile effluent. Methods: LiP producing bacterial isolate was primarily screened by methylene blue assay followed by LiP assay. The standard protocol was used for purification of lignin peroxidase and purified LiP was finally used for degradation of textile dyes. Results: 57 bacterial isolates were screened for lignin peroxidase activity. Isolate LiP-RL5 showed maximum activity (19.8 ±0.33 %) in terms of methylene blue reduction in comparison to others. Biochemical and molecular characterization of LiP-RL5 showed 99 % similarity with P. fluorescens. Lignin peroxidase activity was increased by 50 % after optimization of cultural conditions. Maximum enhancement in the activity was achieved when peptone was used as a nitrogen source. LiP from P. fluorescens LiP-RL5 was further purified up to 2 folds. SDS-PAGE analysis revealed a single protein band of approximately 40 kDa. Enzyme also showed high catalytic efficiency with Km= 6.94 mM and Vmax= 78.74 μmol/ml/min. Purified enzyme was able to decolorize the simulated textile effluent up to 45.05 ±0.28 % after 40 minutes. Conclusion: : High catalytic efficiency of purified LiP from P. fluorescens LiP-RL5 suggests its utility as a potential candidate for biodegradation of toxic dyes in the industrial effluent, which could be successfully utilized for wastewater treatment at commercial level.

Characterization and Performance Analysis of an Adsorptive Polyacrylonitrile based Hydrogel for Heavy Metals Removal

is a key technology for heavy metals removal from industrial effluents. The use of adsorbent polymers is considered to be an attractive solution for wastewater treatment due to their high selectivity for certain heavy metals. Through the current study, an adsorptive polyacrylonitrile based hydrogel blend was used to examine heavy metals removal in simulated effluents incorporating chromium and nickel. Moreover, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) in conjunction to an Energy Dispersive X-Ray Spectroscopy (EDX) were used for characterization of the polymeric blend structure. Finally, for surface evaluation, the specific surface area and the pore size distribution Brunauer-Emmett-Teller (BET) analysis techniques were used together with electrical conductivity measurements The obtained results from FTIR showed the appearance of the original bands of raw materials (polyacrylonitrile (PAN), polyvinyl alcohol and polyaniline (PAni) and the change of the peaks position confirmed the hydrolysis and combination of starting materials into the polymeric blend. Surface morphology studies showed that this gel has porous surface with an average pore size and surface area of 0.73 nm and 17.3 m2/g, respectively. Moreover, Electrical conductivity measurements indicated the presence of PAni in the polymeric blend assisted in the increase in conductivity of PAN. Finally, the different parameters of the polymeric hydrogel blend were investigated through swelling water ratio (SWR) and conventional adsorption processes at different operating conditions such as; initial salt concentration, pH and contact time. The maximum chromium adsorption results were (12.44 mg/g for 10 mg/L initial salt concentration), (10.46 mg/g for 5.5 pH) and (4.91 mg/g for 1 hr. contact time). Whereas, the maximum nickel adsorption was (7.67 mg/g for 20 mg/L initial salt concentration), (7.57 mg/g for 7 pH) and (6 mg/g for 2 hrs. contact time).

Simulated solar photocatalytic ozonation of contaminants of emerging concern and effluent organic matter in secondary effluents by a reusable magnetic catalyst

A magnetic TiO2/Fe3O4/activated carbon composite was used as a photocatalyst for the removal of contaminants of emerging concern (CECs) and effluent organic matter (EfOM) of real and simulated effluents from municipal wastewater treatment plants (MWWTPs). While the catalyst showed limited activity under simulated solar irradiation in the absence of ozone, the CECs were completely eliminated and dissolved organic carbon (DOC) removal efficiencies reached up to more than 75% by simulated solar photocatalytic ozonation. The effects of EfOM (0–30 mg·L−1 DOC), carbonate/bicarbonate (0–60 mg·L−1 IC) and PO4-P (0–3.5 mg·L−1) concentrations of the secondary effluent on the photocatalytic activity was studied. Both EfOM and carbonate/bicarbonate concentration accelerated the DOC removal in single ozonation experiments (i.e., absence of catalyst and radiation) due to the presence of initiators of the hydroxyl radical chain, the formation of secondary oxidants (i.e., hydrogen peroxide and carbonate radical) and the buffering capacity of the effluent. However, the interaction of EfOM and carbonate/bicarbonate with the catalyst brought about a decrease of its photocatalytic activity. Phosphates, in the concentration range studied, did not influence appreciably the catalytic activity. The reusability of the catalyst was evaluated through eight consecutive simulated solar phototacalytic ozonation runs. Samples of fresh and reused catalysts were examined by bulk composition analysis, N2 adsorption-desorption isotherms, XRD, XPS, SQUID magnetometry and the pHPZC. Despite some changes in the porous structure and the fixation of some oxygen groups on the carbon surface as a result of ozonation, the catalyst showed good stability and the oxidation efficiency was maintained through runs.

Adsorption of 3-Aminopyridine (3AP) from aqueous solution using sugarcane bagasse activated carbon (SBAC)

Abstract Adsorption of 3-Aminopyridine (3AP) from simulated effluent using sugarcane bagasse activated carbon (SBAC) was studied based on batch and continuous operations. Characterization of synthesized SBAC was performed initially using BET and SEM analysis. Different batch experiments were performed to understand the effect of operating parameters such as initial concentration, pH, SBAC dose, time and temperature to understand the effect on the extent of adsorption. The maximum adsorption capacity for batch adsorption was established as 54.4 mg/g whereas the maximum extent of removal was 97.6 % under optimized conditions. The observed data at equilibrium was found to be best fitted to Freundlich and Langmuir adsorption isotherms. Kinetic study revealed that pseudo-second order mechanism prevailed. Desorption of 3AP using ethanol showed good reuse efficacy for five cycles. Column adsorption experiments were also performed under varying SBAC bed height, concentration of 3AP and volumetric flow rate of 3AP solution to determine the breakthrough parameters. The fitting of the Yoon–Nelson and Thomas adsorption models to the obtained breakthrough data was studied and found to be satisfactory. Maximum adsorption capacity of SBAC for adsorption of 3AP in continuous operation was established as 65.6 mg/g. The obtained results demonstrated very good performance of SBAC for effective removal of 3AP in both batch and column operations.

Powdered biosorbent from pecan pericarp (Carya illinoensis) as an efficient material to uptake methyl violet 2B from effluents in batch and column operations

The application of dyes in industrial processes has become a growing preoccupation due to the high quantities of colored effluents generated, which need previous treatment before being discarded in water bodies. A powdered biosorbent was then prepared from pecan pericarp and HCl, in order to treat colored effluents containing the dye methyl violet 2B (MV2B) using batch and fixed-bed operation modes. The new biosorbent, so-called powdered pecan pericarp (PPP), was characterized by functional groups related to cellulose, lignin, and hemicellulose. In addition, the material was composed of particles with different sizes, amorphous structure, and rugous surface. The best pH for MV2B biosorption on the PPP was 8.5. The kinetic profile was better described by the general order model, being the equilibrium rapidly reached in the first 5 min for different initial concentrations MV2B. The equilibrium curves were better described by the Langmuir model, indicating homogenous biosorption. The maximum biosorption capacity of 642 mg g−1 was reached at 328 K. Biosorption was favorable and endothermic. PPP has removed 94.1% of color in the simulated effluent. The fixed-bed assays revealed that the column packed with PPP could operate during 52.5 h with a height of 25 cm. The Thomas, Bohart-Adams, and Yoon-Nelson models were suitable to describe the dynamic curves. Therefore, PPP can be used as an efficient and fast biosorbent to treat textile effluents containing MV2B dye.

Ca–Al, Ni–Al and Zn–Al LDH powders as efficient materials to treat synthetic effluents containing o-nitrophenol

Abstract Powdered layered double hydroxides (LDH) based on calcium-aluminum (Ca–Al), nickel-aluminum (Ni–Al), and zinc-aluminum (Zn–Al) were synthesized with the purpose to evaluate the removal of o-nitrophenol from synthetic effluents by adsorption. It was verified that Ca–Al, Ni–Al, and Zn–Al LDHs presented a typical layered structure confirming the successful synthesis. o-nitrophenol adsorption on the LDH powders was favored at a pH of 5.0, being attained removal percentages from 70 to 90%, depending on the material. Kinetic experimental data obeyed the general order model, while, Sips represented the experimental equilibrium behavior of the three materials adequately. The maximum adsorption capacities were 135.1 mg g−1,122.1 mg g−1 and 130.3 mg g−1 for Ca–Al, Ni–Al, and Zn–Al LDHs, respectively. For simulated effluent, it was attained a removal of up to 60.3% using Ni–Al LDH. In a general way, the layered double hydroxides based on Ca–Al, Ni–Al, and Zn–Al exhibited an interesting potential as adsorbent materials for the treatment of simulated effluents containing o-nitrophenol. Ni–Al is preferred due to its better performance in the treatment of simulated effluents and higher regeneration potential.

Implication of Greener Biocomposite Bead for Decontamination of Nickel(II): Column Dynamics Study

The present study reports on the potential of greener Biocomposite designed by living cells of mutated Bacillus sp. integrated passively with alginate to decontaminate Nickel(II) from aqueous medium by continuous column process in order to ascertain its actual environmental application. The impact of working parameters was investigated, showing better execution at a low flow rate (4 mL min−1) and highest bed depth (25 cm). The percentage removal was found to be 80.76% at saturation with a sorption capacity of ~ 54 mg g−1 using an influent concentration of 50 mg L−1. The dynamic behaviour of the processes was well defined by Yoon–Nelson and Thomas kinetic model. Special emphasis was directed to mass transfer phenomenon using suitable mathematical expressions while different kinetic models have their limitations. The resistance of mass transfer initially depended on porous diffusion (PD) prior to the proportion of outflow being 3%, ~ 8% and 12% and subsequent metal removal were controlled by both film mass transfer and PD for Nickel(II) solution 100, 50 and 20 mg L−1, respectively. Biocomposite was characterized by FTIR, SEM-EDXA and elemental analyzer which conveniently ascertained the interactions of metal to composite through electrostatic, complexation and/or chelation. Nickel(II) was recovered to the extent of 92% using 0.1 M HCl as eluant in six consecutive cycles. The Biocomposite was also efficient to decontaminate Nickel(II) from simulated effluent, where breakthrough modeling and mass transfer kinetics revealed a similar trend to the monometallic solution, thereby ensuring its prospect for industrial practice.

Evaluation of Ocotea puberula bark powder (OPBP) as an effective adsorbent to uptake crystal violet from colored effluents: alternative kinetic approaches.

The Ocotea puberula bark powder (OPBP) was evaluated as an effective adsorbent for the removal of crystal violet (CV) from colored effluents. OPBP was characterized and presented a surface with large cavities, organized as a honeycomb. The main functional groups of OPBP were O-H, N-H, C=O, and C-O-C. The adsorption of CV on OPBP was favorable at pH9 with a dosage of 0.75gL-1. The Avrami model was the most suitable to represent the adsorption kinetic profile, being the estimated equilibrium concentration value of 3.37mgL-1 for an initial concentration of 50mgL-1 (CV removal of 93.3%). The equilibrium was reached within 90min. The data were better described by the Langmuir isotherm, reaching a maximum adsorption capacity of 444.34mgg-1 at 328K. The Gibbs free energy ranged from - 26.3554 to - 27.8055kJmol-1, and the enthalpy variation was - 11.1519kJmol-1. The external mass transfer was the rate-limiting step, with Biot numbers ranging from 0.0011 to 0.25. Lastly, OPBP application for the treatment of two different simulated effluents was effective, achieving a removal percentage of 90%.

Continuous Sorption of Chromium Ions from Simulated Effluents using Citric Acid Modified Sweet Potato Peels

Adsorptive removal of chromium ion in aqueous medium using activated sweet potato peel (SPP) was studied in a laboratory-scale fixed bed column. Specifically, the effect of process parameters such as bed depth, flowrate and chromium ion concentration in aqueous solution, on the adsorption efficiency of the acid modified sweet potato peel was examined. Column adsorption analysis showed that at the flow rate of 0.5 cm3/min, bed height of 6 cm and column influent concentration of 30 mg/dm3, the optimum chromium (VI) ion removal of 87.5% was attained with the equilibrium adsorption capacity of 2.4548 mg/g. Continuous adsorption models such as Yoon-Nelson, Adam-Bohart and the Bed-Depth Service Time (BDST) model, were used to analyse the experimental data and based on correlation coefficient, BDST model best aligned with the obtained experimental data with correlation coefficient, R2, value of 96.43%. The bed capacity, No, and the rate constant, Ka, were calculated as 4.259 mg/dm3 and 0.01045 L/mgmin respectively at optimum column conditions. Results confirmed that acid modified SPP can be used to remove or reduce concentrations of Cr (VI) ions to allowable limits before disposal into water bodies.
 Keywords: Continuous sorption, chromium ions, sweet potato peel, kinetic isotherms, breakthrough curves

The Treatment of Absorbable Organic Halogens and Organic Compounds in Simulated Bleaching Effluents Through the Response Surface Methodology Optimized Fenton System

In this study, the effects of four main factors on the removal of absorbable organic halogens were evaluated by response surface methodology, and the changes of absorbable organic halogens components were characterized by gas chromatography-mass spectrometer during the Fenton reaction. The high regression coefficient (R2 = 0.9028) and the low coefficient of variation (7.45%) indicated that the model was accurate in predicting the experimental results. The optimized pH, Fe2+ concentration, molar ratio of H2O2/Fe2+ and reaction time were respectively 3.4, 16.3 mM, 22.5 and 1.2 h. Consequently, 93.8% of absorbable organic halogens were removed under the optimized condition. The initial pH is the most important factor impacting the absorbable organic halogens removal. Furthermore, gas chromatography-mass spectrometer revealed that 25 out of 28 organic compounds including 7 absorbable organic halogens were thoroughly removed. Conclusively, Fenton reaction can effectively remove absorbable organic halogens from the simulated bleaching effluent.

Synthesis of a novel polysuccinimide based resin for the ultrahigh removal of anionic azo dyes from aqueous solution

A novel hyper-cross-linked polyamide resin (PSI-PA) has been synthesized for the ultrahigh removal of Congo red (CR) and Eriochrom Black T (EBT) from aqueous solution. The mesoporous resin, having a specific surface area (98.80 m2 g−1), showed maximum adsorption capacity (Qmax) of 522.18 mg g−1 for CR (pH 9.0) and 460.34 mg g−1 for EBT (pH 6) at room temperature. The adsorption of these dyes was rapid and the equilibrium was attained within 4 h. The kinetic data was well-fitted by pseudo-second-order rate equation. Analysis of the surface chemical composition of loaded PSI-PA by XPS revealed the appearance of a new peak at around 166.0 eV (S 2p), confirming the adsorption of the sulfur-based dyes onto the resin. Examination of experimental data of dyes adsorption by a variety of non-linear adsorption isotherms and kinetic models suggested that the Langmuir model exhibited the best fit with high correlation coefficients for both CR (R2 = 0.9966) and EBT (R2 = 0.9934). PSI-PA has been extensively characterized by FT-IR, solid state 13C (CP-MAS) NMR, EDS, TGA and BET analysis. Moreover, PSI-PA exhibited 82% removal efficiency for dyes in simulated effluents, manifesting its promise and utility for treating industrial effluent.

MnO2/Vulcan-Based Gas Diffusion Electrode for Mineralization of Diazo Dye in Simulated Effluent

Treatments of simulated effluent solutions containing the Reactive Black 5 (RB5) were carried out by electrochemical, photoelectrochemical, electro-Fenton and photoelectro-Fenton methods using a one-compartment cell with a boron-doped diamond anode and a 3% of manganese dioxide nanoflowers supported on a carbon Vulcan XC72 gas diffusion electrode cathode. In the photo-assisted processes, the solution was irradiated using a 40-W UVC lamp immersed in the treated solution. For Fenton-based processes, only 5 min was required to attain 95% (photoelectro-Fenton) and 93% (electro-Fenton) RB5 dye degradation. When conversion to CO2 is taken into account after 6-h treatment, electrochemical method mineralized ~ 13% of the organic load whereas removals greater than 90% were attained using the Fenton-based processes. These completely different results can be explained by the distinct spatial availability of the generated hydroxyl radical: only near the anode surface as in electrochemical-based processes or added to those distributed across the solution bulk as in Fenton-based processes.

Powdered biosorbent from the mandacaru cactus (cereus jamacaru) for discontinuous and continuous removal of Basic Fuchsin from aqueous solutions

A powdered biosorbent was developed by the processing of mandacaru (Cereus jamacaru) leaves, and tested as an alternative material to treat solutions containing Basic Fuchsin dye (BF) in discontinuous and continuous systems. A simple model (ILE model) based in the Langmuir isotherm was developed to predict the continuous biosorption. PML was a fast and efficient biosorbent, attaining biosorption capacity near to 400 mg g−1. PML was also efficient to treat a simulated effluent, providing color removal percentages around 90%. In relation to the continuous operation using PML, an excellent bed performance was found, with breakthrough time of 14 h, and length of mass transfer zone of 1.48 cm. The ILE model was able to predict the breakthrough curve. It can be concluded that PML is a low cost and efficient biosorbent to be used for decolorization of liquid streams in discontinuous and continuous systems.

Araticum (Annona crassiflora) seed powder (ASP) for the treatment of colored effluents by biosorption.

Dyes are widely used in many industrial sectors, many contain harmful substances to human health, and their release into the environment entails several environmental problems, generating a major worldwide concern as water resources are increasingly limited. The development of cheap and efficient biosorbents that remove these pollutants is of utmost importance. In this study, powdered seeds of the araticum fruit (Annona crassiflora) were used in the biosorption of crystal violet (CV) dye from aqueous solutions and simulated textile effluents. Through the characterization techniques, it can be observed that the material presented an amorphous structure, containing an irregular surface composed mainly by groups containing carbon, hydrogen, and oxygen. CV biosorption was favored at the natural pH of the solution (7.5) for a dosage of 0.7gL-1 of araticum seed powder. The pseudo-second-order model was the most suitable to represent the biosorption kinetics in the removal of the CV. Biosorption capacity reached equilibrium in the first minutes at the lowest concentrations, and, at the highest, after 120min. The equilibrium data were well represented by the Langmuir model, with a maximum biosorption capacity of 300.96mgg-1 at 328K. Biosorption had a spontaneous and endothermic nature. In the treatment of a simulated effluent, the biosorbent removed 87.8% of the color, proving to be efficient. Therefore, the araticum seeds powder (ASP) can be used as a low-cost material for the treatment of colored effluents containing the crystal violet (CV) dye.

Solid wastes from the enzyme production as a potential biosorbent to treat colored effluents containing crystal violet dye.

Sugarcane bagasse, a largely available waste worldwide, was submitted to solid-state fermentation (SSF) using the fungus Metarhizium anisopliae, aiming to produce enzymes. The solid waste generated from SSF was tested as an alternative biosorbent to treat colored effluents containing crystal violet (CV) dye. The biosorbent, here named BW (bagasse waste), was characterized, and experimental tests were performed to verify the influence of pH and dosage on the CV biosorption. Isotherms and biosorption kinetics were performed, and the biosorption thermodynamic parameters were determined. The potential of BW was also evaluated for the treatment of a simulated textile effluent. The maximum biosorption capacity was 131.2mgg-1 at 328K, and the Liu was the most appropriate model to represent equilibrium data. The biosorption was spontaneous and endothermic. The use of BW in the simulated effluent showed that it is an efficient material, reaching color removal values of 85%. Therefore, the sugarcane bagasse generated from SSF can be considered a potential biosorbent to remove CV from textile effluents. This finding is relevant from the total environment viewpoint, since, at the same time, SSF generates enzymes and a solid waste, which in turn can be used as biosorbent to treat colored effluents.