A synergistic approach combining Adsorption and Biodegradation for effective treatment of Acid Blue 113 dye by Klebsiella grimontii entrapped Graphene Oxide-Calcium Alginate Hydrogel Beads.

This study investigated the degradation of Acid Blue 113 (AB 113) dye using Klebsiella grimontii entrapped Graphene Oxide-Calcium Alginate Hydrogel beads (KG-GO-CA) in a Fluidized Bed Bioreactor (FBBR) under varying inlet loading rates. The minimum fluidization velocity of the KG-GO-CA hydrogel beads in FBBR was found to be 0.15 mm/s. The KG-GO-CA beads showed a maximum removal efficiency of 94.6% at an inlet flow rate of 20 mL/h over 15 days. Reusability studies indicated a removal efficiency of 70.6 ± 2.5% for AB 113 after the 12th cycle. Langmuir adsorption isotherm showed the best fit (R2 = 0.98724) with model parameters of Qm (203.83 mg/g) and Ki (0.0101 L/g). The study also confirmed that treated wastewater was more environmentally safe for domestic and commercial uses than untreated wastewater. The research highlights the potential use of KG-GO-CA hydrogel beads for removing dyes from wastewater.

Construction and performance assessment of Recirculating packed bed biofilm reactor (RPBBR) for effective biodegradation of p-cresol from wastewater.

Wastewater containing excess phenolic compounds is considered a major environmental concern due to its adverse impacts on the ecosystem. In this work, an effort has been given to treat the p-cresol from wastewater using Recirculating Packed Bed Biofilm Reactor (RPBBR). The process parameters, namely inoculum dose, pH, and NaCl (w/v) concentration were optimized to enhance the specific growth and obtained to be 14 ml, 7.0, and 1% NaCl (w/100 ml), respectively. Maximum p-cresol removal efficiency of 99.36±0.2% was achieved at 100 mg L-1 of p-cresol. First-order rate constants were found to be 0.70 day-1 and 0.96 day-1 for batch and continuous mode, respectively. The intermediates were analysed using FT-IR and GC-MS analysis. Pseudomonas fluorescens was used to assess bacterial toxicity and observed that the toxicity was reduced in case of treated wastewater. Finally, the performance of continuous RPBBR was better than the batch mode.

Assessment of biodegradation kinetics and mass transfer aspects in attached growth bioreactor for effective treatment of brilliant green dye from wastewater.

In this study, Bacillus licheniformis immobilized with low-density polyethylene (LDPE) was employed to degrade Brilliant Green (BG) dye from wastewater in a packed bed bioreactor (PBBR). Bacterial growth and extracellular polymeric substance (EPS) secretion were also assessed under different concentrations of BG dye. The impacts of external mass transfer resistance on BG biodegradation were also evaluated at different flow rates (0.3-1.2 L/h). A new mass transfer correlation [Formula: see text] was proposed to study the mass transfer aspects in attached-growth bioreactor. The intermediates, namely 3- dimethylamino phenol, benzoic acid, 1-4 benzenediol, and acetaldehyde were identified during the biodegradation of BG and, subsequently degradation pathway was proposed. Han - Levenspiel kinetics parameters µmax and Ks were found to be 0.185 per day and 115 mg/L, respectively. The new insight into mass transfer and kinetics support the design of efficiently attached growth bioreactor to treat a wide range of pollutants.

Biodegradation of Congo Red Dye Using Lysinibacillus Species in a Moving Bed Biofilm Reactor: Continuous Study and Kinetic Evaluation.

The objective of this work was to develop a low-cost and efficient biocarrier for biodegradation of azo dye (i.e., Congo red (CR) dye). The potential bacterial species, i.e., Lysinibacillus fusiformis KLM1 and Lysinibacillus macrolides KLM2, were isolated from the dye-contaminated site. These bacterial species were immobilized onto the polypropylene-polyurethane foam (PP-PUF) and employed in a moving bed biofilm reactor (MBBR) for the treatment of CR dye. The effectiveness of the MBBR was investigated by operating the bioreactor in a continuous mode at various initial CR dye concentrations (50-250 mg/L) for 113 days. The removal efficiency was found in the range of 88.4-64.6% when the initial dye concentration was varied from 50 to 250 mg/L. The maximum elimination capacity (EC) of 213.18 mg/L.d was found at 250 mg/L of CR dye concentration. In addition, the CR dye utilization rate in the MBBR was studied by using two kinetics, namely, first-order and second-order (Grau) models. The high regression coefficients (R2 > 0.97) and the satisfactory root mean square (RMSE) values (0.00096-0.02610) indicated the reasonable prediction of CR dye degradation rate by the Grau model.

Biodegradation and detoxification study of triphenylmethane dye (Brilliant green) in a recirculating packed-bed bioreactor by bacterial consortium.

In the last few decades, Brilliant green (BG) dye is widely employed to colour the fabric materials in various industries (e.g. textile, pulp and paper, etc.). The wastewater containing BG dye emerges as a major challenge among the researchers due to its toxic, mutagenic, and carcinogenic effects on human beings and marine life. In this context, the present study is mainly focused on the biodegradation of BG dye present in wastewater. The biodegradation of BG dye was performed in an indigenously designed recirculating packed bed bioreactor (RPBBR). Modified Polypropylene-Polyurethane foam (PP-PUF), a support packing material, was immobilised with a newly isolated bacterial consortium of Enterobacter asburiae strain SG43 (BGT1) and Alcaligenes sp. SY1 (BGT2). The bioreactor was operated under various organic loading rates (OLRs) of 2.7, 1.27, 0.93, 0.71, and 0.53 kg COD/m3.d-1 with a hydraulic retention time (HRT) of 4 days. The bioreactor exhibited the maximum BG dye removal efficiency of 91%. Proton Nuclear Magnetic Resonance (1H NMR), UV-Vis spectroscopy, Gas chromatography-mass spectrometry (GC-MS), and Fourier Transform Infrared Spectroscopy (FTIR) depicted the biodegradation of BG dye. Phaseolus mungo seeds germinated in BG dye biodegraded wastewater was significantly high (83.56%) than the untreated wastewater (32.4%), which was reasonably subjected to the detoxification of treated wastewater.

A comprehensive evaluation of the integrated photocatalytic-fixed bed bioreactor system for the treatment of Acid Blue 113 dye.

This work investigated the performance of the integrated system (i.e., a Photocatalytic reactor followed by a Fixed bed bioreactor (PC-FBR)) for the degradation of complex Acid Blue 113 from wastewater. Initially, a Photocatalytic reactor was employed to improve the biodegradability index (i.e., BOD/COD) of wastewater from 0.21 ± 0.0062 to 0.395 ± 0.0058. The preliminary photocatalytic oxidation study revealed a maximum of 86.42 ± 0.33 % dye removal at TiO2 loading of 1.5 g/L and an initial concentration of 50 mg/L of AB 113. An integrated reactor system significantly achieved a maximum of 92 ± 2.6 % of dye removal efficiency under a retention time of 120 hr. The stand-alone FBR dye shock loading study suggested that the reactor system was reasonably able to further restore its degradation efficiency. Langmuir-Hinshelwood kinetic model, Monod model, and Andrew-Haldane model were fitted. The bacterial toxicity assessment was carried out using the Pseudomonas fluorescens.

Removal of gaseous benzene by a fixed-bed system packed with a highly porous metal-organic framework (MOF-199) coated glass beads.

The utility of nanomaterial adsorbents is often limited by their physical features, especially fine particle size. For example, a large bed-pressure drop is accompnied inevitably, if fine-particle sorbents are used in a packed bed system. To learn more about the effect of adsorbent morphology on uptake performance, we examined the adsorption efficiency of metal-organic framework 199 (MOF-199) in the pristine (fine powder) form and after its binding on to glass beads as an inert support. Most importantly, we investigated the effect of such coatings on adsorption of gaseous benzene (0.1-10 Pa) in a dry N2 stream, particularly as a function of the amount of MOF-199 loaded on glass beads (MOF-199@GB) (i.e., 0,% 1%, 3%, 10%, and 20%, w/w) at near-ambient conditions (298 K and 1 atm). A 1% MOF-199 load gave optimal performance against a 0.1 Pa benzene vapor stream in 1 atm of N2, with a two-to five-fold improvement (e.g., in terms of 10% breakthrough volume [BTV] (46 L atm [g.MOF-199)-1], partition coefficient at 100% BTV (3 mol [kg.MOF-199]-1 Pa-1), and adsorption capacity at 100% BTV (20 mg [g.MOF-199]-1 (areal capacity: 8.8 × 10-7 mol m-2) compared with those of 3%, 10%, and 20% loading. The relative performance of benzene adsorption was closely associated with the content of MOF-199@GB (e.g., 1% > 3% > 10% > 20%) and the surface availability (m2 [g.MOF-199]-1) such as 291 > 221 > 198 > 181, respectively. This study offers new insights into the strategies needed to expand the utility of finely powdered MOFs in various environmental applications.

Highly efficient bio-adsorption of Malachite green using Chinese Fan-Palm Biochar (Livistona chinensis).

The discharge of effluents from the textile industry is a multidimensional problem that affects the ecosystem in many ways. Though many new technologies are being developed, it remains to be seen which of those can be practiced in a real scenario. The current investigation attempts to absorb the Malachite Green, an effluent from textile dye using Chinese Fan Palm Seed Biochar. Accordingly, biochar was prepared using fruits of Chinese Fan Palm (Livistona chinensis) tree. The fruit also yielded a significant amount of biochar and bio-oil. 1.346 kg of fresh and cleaned fruit was fast pyrolyzed at 500 °C in a laboratory-scale Pyrolyzer resulting in 0.487 kg of biochar and 0.803 L of bio-oil. The remaining fruit matter was converted to gaseous products. The kinetics of dye removal were studied and the parameters were determined. The study advocates that the Langmuir isotherm model simulates the adsorption experiment, to a good extent. From the plot, the maximum (monolayer) adsorption capacity, Qm was determined to be 21.4 mg/g. The suitability of the Langmuir isotherm model onto biochar was established by the high correlation coefficient, R2 that was higher than 0.97.

Construction of biotreatment platforms for aromatic hydrocarbons and their future perspectives.

Aromatic hydrocarbons (AHCs) are one of the major environmental pollutants introduced from both natural and anthropogenic sources. Many AHCs are well known for their toxic, carcinogenic, and mutagenic impact on human health and ecological systems. Biodegradation is an eco-friendly and cost-effective option as microorganisms (e.g., bacteria, fungi, and algae) can efficiently breakdown or transform such pollutants into less harmful and simple metabolites (e.g., carbon dioxide (aerobic), methane (anaerobic), water, and inorganic salts). This paper is organized to offer a state-of-the-art review on the biodegradation of AHCs (monocyclic aromatic hydrocarbons (MAHs) and polycyclic aromatic hydrocarbons (PAHs)) and associated mechanisms. The recent progress in biological treatment using suspended and attached growth bioreactors for the biodegradation of AHCs is also discussed. In addition, various substrate growth and inhibition models are introduced along with the key factors governing their biodegradation kinetics. The growth and inhibition models have helped gain a better understanding of substrate inhibition in biodegradation. Techno-economic analysis (TEA) and life cycle assessment (LCA) aspects are also described to assess the technical, economical, and environmental impacts of the biological treatment system.

Performance evaluation of a continuous packed bed bioreactor: Bio-kinetics and external mass transfer study.

The biodegradation of naphthalene using low-density polyethylene (LDPE) immobilized Exiguobacterium sp. RKS3 (MG696729) in a packed bed bioreactor (PBBR) was studied. The performance of a continuous PBBR was evaluated at different inlet flow rates (IFRs) (20-100 mL/h) under 64 days of operation. The maximum naphthalene removal efficiency (RE) was found at low IFR, and it further decreased with increasing IFRs. In a continuous PBBR, the external mass transfer (EMT) aspect was analysed at various IFRs, and experimental data were interrelated between Colburn factor (JD) and Reynolds number (NRe) as [Formula: see text] . A new correlation [Formula: see text] was obtained to predict the EMT aspect of naphthalene biodegradation. Andrew-Haldane model was used to evaluate the bio-kinetic parameters of naphthalene degradation, and kinetic constant νmax, Js, and Ji were found as 0.386 per day, 13.6 mg/L, and 20.54 mg/L, respectively.

Biodegradation of Congo red dye in a moving bed biofilm reactor: Performance evaluation and kinetic modeling.

The biodegradation of Congo red dye was performed using polyurethane foam-polypropylene immobilized Bacillus sp. MH587030.1 in a moving bed biofilm reactor (MBBR). The central composite design (CCD) based response surface methodology (RSM) was used to optimize the process parameters; pH, Congo red concentration, and media filling ratio, and optimum conditions were observed to be 7.0, 50 mg/L, and 45%, respectively in batch MBBR. At optimum condition, MBBR was operated in continuous mode at different flow rates (25-100 mL/h) over a period of 564 h. The maximum removal efficiency (RE) and elimination capacity (EC) were obtained as 95.7% and 57.6 mg/L·day, respectively under steady-state. The kinetics of Congo red biodegradation at various flow rates were evaluated by a modified Stover-Kincannon model, and kinetic constants; KB and Umax were found to be 0.253 g/L·day and 0.263 g/L·day, respectively.

A novel comparative study of modified carriers in moving bed biofilm reactor for the treatment of wastewater: Process optimization and kinetic study.

In this work, modified plastic carriers; polypropylene (PP), low-density polyethylene- polypropylene (LDPE-PP), and polyurethane foam-polypropylene (PUF-PP) were developed and used in moving bed bioreactor (MBBR) for the wastewater treatment containing naphthalene. To optimized the process parameters using response surface methodology (RSM), two numerical variables; pH (5.0-9.0) and hydraulic retention time (HRT) (1.0-5.0 day) along with the type of carriers (PP, LDPE-PP, and PUF-PP) were selected as a categorical factor. At 7.0 pH and 5 days HRT, maximum removal efficiencies were observed to be 72.4, 84.4, and 90.2% for MBBR packed with PP, LDPE-PP, and PUF-PP carriers, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis reveals catechol and 2-naphthol were observed as intermediate metabolites for naphthalene degradation. Modified Stover-Kincannon model was applied for biodegradation kinetic and constants were observed as Umax: 0.476, 0.666, and 0.769 g/L.day and KB: 0.565, 0.755, and 0.874 g/L.day for PP, LDPE-PP, PUF-PP, respectively.

Biodegradation of methylene blue dye in a batch and continuous mode using biochar as packing media.

Bacterial species for metabolizing dye molecules were isolated from dye rich water bodies. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting methylene blue (MB) batch degradation studies with the bacterial strains using NaCl-yeast as a nutrient medium. The most suitable bacterial species was Alcaligenes faecalis (A. faecalis) according to 16S rDNA sequencing. Process parameters were optimized and under the optimum conditions (e.g., inoculum size of 3 mL, temperature of 30 °C, 150 ppm, and time of 5 days), 96.2% of MB was removed. Furthermore, the effectiveness for the separation of MB combining bio-film with biochar was measured by a bio-sorption method in a packed bed bioreactor (PBBR) in which microbes was immobilized. The maximum MB removal efficiencies, when tested with 50 ppm dye using batch reactors containing free A. faecalis cells and the same cells immobilized on the biochar surface, were found to be 81.5% and 89.1%, respectively. The PBBR operated in continuous recycle mode at high dye concentration of 500 ppm provided 87.0% removal of MB through second-order kinetics over 10 days. The % removal was found in the order of PBBR>Immobilized batch>Free cell. The standalone biochar batch adsorption of MB can be described well by the pseudo-second order kinetics (R2 ≥ 0.978), indicating the major contribution of electron exchange-based valence forces in the sorption of MB onto the biochar surface. The Langmuir isotherm suggested a maximum monolayer adsorption capacity of 4.69 mg g-1 at 40 °C which was very close to experimentally calculated value (4.97 mg g-1). Moreover, the Casuarina seed biochar was reusable 5 times.