Browsing by Author "Raghuvanshi, Smita"

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Application of a hybrid biofilter column for the removal of Cr(VI) from aqueous solution using an indigenous bacterial strain Pseudomonas taiwanensis
(Taylor & Francis, 2016-02-01) Gupta, Suresh; Raghuvanshi, Smita; Majumder, Subhajit
In the present study, a laboratory-scale biofilter column was designed and fabricated. It was packed with a mixture of coal and compost as a packing medium. The column was enriched with an indigenous bacterial strain Pseudomonas taiwanensis isolated from aerobic mixed culture of Sewage Treatment Plant, BITS-Pilani, Pilani campus. The removal of hexavalent chromium [Cr(VI)] from aqueous solution was investigated in the biofilter column. The entire biofiltration operation was divided into five phases (I to V) for a period of 63 days. Biofilter column was subjected to shock loading conditions for 20 days immediately after 63 days of operation. The maximum removal efficiency of 89.4% was obtained during phase V for Cr(VI) inlet concentration of 40 mg L−1. During shock loading, maximum removal efficiency was obtained as 90% for 48.5–50 mg L−1 of initial Cr(VI) concentration. Kinetic parameters of biofiltration process for Cr(VI) removal were also determined by fitting Michaelis-Menten kinetic model with experimental data. The Michaelis-Menten kinetic constants were obtained as 0.258 mg L−1 min−1 and 26.83 mg L−1. It was found that Ottengraf-Van den Oever model with zero-order diffusion limitation fit the experimental data quite well for phases III, IV, and V with coefficient of determination (R2) values .97, .99, and .984, respectively. A possible method for safe disposal of packing medium was also presented in this study.
Application of novel thermo-tolerant haloalkalophilic bacterium Halomonas stevensii for bio mitigation of gaseous phase CO2: Energy assessment and product evaluation studies
(Elsiever, 2017-04) Gupta, Suresh; Raghuvanshi, Smita; Mishra, Somesh
Present work deals with the bio-mitigation potential of gaseous phase CO2 by chemolithotrophic bacterium Halomonas stevensii isolated from haloalkaliphilic habitat using thiosulfate ion (S2O32−) as an energy source. H. stevensii was tested for various abiotic stress tolerances such as salt [2–12% (w/v)], temperature (10–60 °C) and pH (2–12). Batch studies were conducted for 6 days at 15 (±1) % (v/v) inlet CO2 concentration to find the CO2 fixing capability of H. stevensii under varying concentration of energy substrate i.e. 0, 50 and 100 mM Na2S2O3. Approximately 98% CO2 removal from gaseous phase was achieved at 50 and 100 mM Na2S2O3. Evaluation of CO2 fixation by H. stevensii and carbon allocation into different cellular organic pool (carbohydrate, proteins and primary metabolite) was carried out by growing H. stevensii at 5%, 10% and 15% (v/v) inlet CO2 concentration for the duration of 6 days. The obtained leachate was quantified using chemical technique, FT-IR and GC. Utilization of gaseous phase CO2 by H. stevensii was also proven by conducting the approximate materials balance and energy assessment for the present CO2 fixation process. The mechanism of CO2 metabolism by H. stevensii was evaluated using GC–MS and carbon partitioning into cellular organic pool analysis.
Assessing the bacterial consortium's potential to bio-mitigate CO2 and SO2 from simulated flue gas, wastewater bioremediation, and product characterization
(Elsevier, 2024-12) Raghuvanshi, Smita; Gupta, Suresh
The present study aims to fix carbon dioxide (CO2) and sulfur dioxide (SO2) simultaneously by conducting extensive semi-continuous experiments on the 3 L glass bioreactor to evaluate the potential of bacterial consortium for CO2 (C), SO2 (S), and CO2 + SO2 (CS) gaseous mixture. In this study, the bacterial consortium (Bacillus tropicus SSLMC1, Bacillus cereus SSLMC2) utilizes thiosulfate as an energy source and domestic wastewater (DWW) supplemented with additional minerals as a nutrient source. The maximum CO2 and SO2 mitigation efficiency was obtained as 93.8 % and 91.4 % for CS and S gaseous mixtures, respectively. The biomass concentration, biomass productivity, removal efficiency, and utilization efficiency for the CS gas mixture are comparable with the C and S gas mixture. Simultaneously, various nutrients and pollutants such as BOD, COD, PO43- and CO32- were removed. Fourier Transform Infrared Spectroscopy (FT-IR) and Gas Chromatography-Mass spectroscopy (GC-MS) analysis of cell lysate and cell-free supernatant have indicated the presence of fatty alcohols and long-chain hydrocarbons in all three gaseous mixtures. The present study showed that bacterial consortia can bio-mitigate CO2 and SO2 simultaneously and implement the bio-mitigation study of CO2 and SO2 in a real scenario
Bio-Mitigation of Carbon Dioxide Using Desmodesmus sp. in the Custom-Designed Pilot-Scale Loop Photobioreactor
(MDPI, 2021-09) Gupta, Suresh; Raghuvanshi, Smita; Verma, Sanjay Kumar
Today’s society is faced with many upfront challenges such as the energy crisis, water pollution, air pollution, and global warming. The greenhouse gases (GHGs) responsible for global warming include carbon dioxide (CO2), methane (CH4), nitrous oxide (NOx), water vapor (H2O), and fluorinated gases. A fraction of the increased emissions of CO2 in the atmosphere is due to agricultural and municipal solid waste (MSW) management systems. There is a need for a sustainable solution which can degrade the pollutants and provide a technology-based solution. Hence, the present work deals with the custom design of a loop photobioreactor with 34 L of total volume used to handle different inlet CO2 concentrations (0.03%, 5%, and 10% (v/v)). The obtained values of biomass productivity and CO2 fixation rate include 0.185 ± 0.004 g L−1 d−1 and 0.333 ± 0.004 g L−1 d−1, respectively, at 10% (v/v) CO2 concentration and 0.084 ± 0.003 g L−1 d−1 and 0.155 ± 0.003 g L−1 d−1, respectively, at 5% (v/v) CO2 concentration. The biochemical compositions, such as carbohydrate, proteins, and lipid content, were estimated in the algal biomass produced from CO2 mitigation studies. The maximum carbohydrate, proteins, and lipid content were obtained as 20.7 ± 2.4%, 32.2 ± 2.5%, and 42 ± 1.0%, respectively, at 10% (v/v) CO2 concentration. Chlorophyll (Chl) a and b were determined in algal biomass as an algal physiological response. The results obtained in the present study are compared with the previous studies reported in the literature, which indicated the feasibility of the scale-up of the process for the source reduction of CO2 generated from waste management systems without significant change in productivity. The present work emphasizes the cross-disciplinary approach for the development of bio-mitigation of CO2 in the loop photobioreactor.
Biodegradation kinetics of Cr (VI) by acclimated mixed culture
(JCE, 2011-05) Raghuvanshi, Smita; Gupta, Suresh
Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being investigated. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. It is highly toxic in nature and causes adverse effects on human beings. The present study deals with the removal of hexavalent chromium compound from industrial waste water using biodegradation by an acclimated mixed culture developed from activated sludge. The biodegradation studies are conducted for an initial Cr(VI) concentration ranging from 10-50 mg/L. The enrichment of culture is carried out for a period of 7 days. In these experiments, 100 mL of minimum salt medium (MSM) is autoclaved and added with known amount of acclimated mixed culture obtained from the enrichment procedure. Known amount of Cr(VI) is added in autoclaved MSM to maintain the required concentration of Cr(VI). The flasks are kept in the rotary shaker which is maintained at 37 C and at 150 rpm throughout the biodegradation process. The samples are collected at different intervals. The obtained biomass growth is significant and indicate the considerable decrease in Cr(VI) concentration in the solution The biodegradation rate kinetic parameters are obtained for zero order and three and half order kinetic models.
Biodegradation kinetics of methyl iso-butyl ketone by acclimated mixed culture
(Elsiever, 2009-06-26) Raghuvanshi, Smita
Methyl iso-butyl ketone (MIBK) is a widely used volatile organic compound (VOC) which is highly toxic in nature and has significant adverse effects on human beings. The present study deals with the removal of MIBK using biodegradation by an acclimated mixed culture developed from activated sludge. The biodegradation of MIBK is studied for an initial MIBK concentration ranging from 200–700 mg l−1 in a batch mode of operation. The maximum specific growth rate achieved is 0.128 h−1 at 600 mg l−1of initial MIBK concentration. The kinetic parameters are estimated using five growth kinetic models for biodegradation of organic compounds available in the literature. The experimental data found to fit well with the Luong model (R 2 = 0.904) as compared to Haldane model (R 2 = 0.702) and Edward model (R 2 = 0.786). The coefficient of determination (R 2) obtained for the other two models, Monod and Powell models are 0.497 and 0.533, respectively. The biodegradation rate found to follow the three-half-order kinetics and the resulting kinetic parameters are reported.
Biofilter column for removal of divalent copper from aqueous solutions: Performance evaluation and kinetic modeling
(INFOFNA, 2015) Gupta, Suresh; Raghuvanshi, Smita; Majumder, Subhajit
In recent years, the biofiltration technique has gained significant importance for the removal of toxic organic compounds. However, very limited studies on biofiltration were carried out for the removal of divalent copper [Cu(II)] from aqueous solution using indigenous packing material. There are no reports in the literature that deal with the performance evaluation and kinetic modeling of the biofilter column for the removal of Cu(II). In the present study, a lab- scale biofilter column was fabricated and packed with a mixture of compost and coal as a packing material. The seeding of the column was done using an indigenous bacterial strain Acinetobacter guillouiae. The removal of divalent copper [Cu(II)] was investigated in this column for a period of 55 days. The maximum removal efficiency of 97.5% was achieved during phase II for Cu(II) inlet concentration of 20 mg L−1. During shock loading, maximum removal efficiency obtained was 87% for initial Cu(II) concentration 28.5–30 mg L−1. The Michaelis–Menten kinetic constants obtained were 0.2 mg L−1 min−1 and 13.03 mg L−1. It was found that the Ottengraf model with zero-order diffusion-limitation fits the experimental data quite well for phase II, III and V.
Biofiltration for removal of methyl isobutyl ketone (MIBK): Experimental studies and kinetic modelling
(Taylor & Francis, 2009-08-26) Raghuvanshi, Smita
The present study deals with the biofiltration of methyl isobutyl ketone (MIBK), which is considered to be a highly toxic volatile organic compound. It is released from the paint and petrochemical industries and is one of the major contributors to air pollution. The biofiltration study was carried out on a lab scale for two months in the presence of acclimated mixed culture. The performance of the biofilter column was evaluated for different inlet loads of MIBK at air flow rates ranging from 0.18 to 0.3 m3 h−1. The maximum removal efficiency of 93% was obtained after 60 days of biofilter operation for an inlet MIBK concentration of 0.45 g m−3, and a microbial concentration of 2.36 × 108 CFU g−1 of packing material was obtained. This led to a study of shock loadings for 20 days, by varying the inlet MIBK load and air flow rate after every five days, to observe the behaviour of the biofilter column in removing sudden loads of MIBK. The biokinetic constants r max and K s were obtained using the Michaelis–Menten kinetics and were found to be 1.046 g m−3 and 0.115 g m−3 h−1, respectively, with a coefficient of determination (R 2) of 0.993. The obtained experimental results were validated with the Ottengraf and Van den Oever kinetic model. The critical inlet concentration, critical inlet load and biofilm thickness were also estimated using the results obtained from the model predictions.
Biofiltration: Essentials, Research and Applications
(Wiley, 2012-03) Raghuvanshi, Smita; Gupta, Suresh
Biofiltration: Essentials, Research and Applications
(Wiley, 2012-03-26) Gupta, Suresh; Raghuvanshi, Smita; Majumder, Subhajit
Bioprocess scale-up through experimental design and process simulation: a case study of succinic acid and 3-hydroxypropionic acid
(AIChE, 2025) Raghuvanshi, Smita
The bioprocess scale-up is at the center when developing an upstream process for mass production [1]. Process understanding at the laboratory scale can guide the scale-up rules [2-4]. These rules are broadly classified into maintaining (1) the same mixing time, (2) constant power supplied per unit volume (P/V), (3) constant overall mass transfer coefficient (kLa), and (4) impeller flow numbers [3,4]. Accordingly, different scale-up correlations have been derived and are functions of impeller Reynolds number (Re), impeller tip speed, power transfer per unit volume, and agitation rate [2-4]. At different scales, this correlation-based scale-up can produce comparable biomass [4 and 5]. Thus, in the process of SA mass-production via fermentation, different studies have attempted to scale up fermentative succinic acid (SA) production via yeast. In one study, from an engineered Yarrowia lipolytica PSA02004 via two-stage pH regulation between 5-6 in fed-batch mode a SA titer value of 42.2 g.L-1 with 0.38 g.g-1 yield and 0.84 g.L-1.h-1 productivity is obtained [6]. In the same study, the shake flask scale is translated to the lab-scale reactor at 6.7 L (Working volume: 3L) [7]. Another study in batch mode resulted in an SA titer of 18.4 g.L-1 with a yield of 0.23 g.g-1 at pH 3.0. However, in fed-batch mode, with seven-time feeding, a higher titer value of 76.8 g.L-1 is achieved. The study utilizes an in situ fibrous bed bioreactor (isFBB) of volume 2.5 L [8]. In other studies, via batch or fed-batch mode with multiple feeding mostly near pH 6, the SA values titer and yield in the range of 53.6 g.L-1-209.7 g.L-1 and 0.92 g.g-1 are reported, respectively [9, 10]. However, almost all these studies are limited either to shake flask or to the bioreactor total volume in the range of 1-10 L [6-10].
Carbon dioxide to bio-fuels by mixed and pure microbial cultures isolated from activated sludge: relative evaluation of CO2 fixation, biodiesel production, and thermodynamic analysis
(Wiley, 2019-08-31) Gupta, Suresh; Raghuvanshi, Smita; Mishra, Somesh
In the present work, the CO2(g) bio-mitigation potential (15% [v/v]) of a mixed microbial population, Enterobacter cloacae and Pseudomonas putida, is thermodynamically assessed and compared at different Fe(II) concentrations (energy source). CO2(g) removal efficiency values are evaluated on per-day basis for all cultures and found maximum for the mixed microbial population. Approximate material balance and thermodynamic assessment of the CO2(g) bio-mitigation studies have revealed that among all cultures, the mixed microbial population shows the highest actual CO2 utilization efficiency (R.RCO2) of 57.67 (±0.04)%. Leachate (biomass + cell free supernatant) obtained from CO2 bio-mitigation batch studies were analyzed using FTIR and gas chromatography–mass spectroscopy. The results obtained have shown the presence of fatty acids and hydrocarbons in considerable amounts. The fatty acids obtained from cultures have shown the presence of a carbon chain length in the range of C7–C25, which makes it a potential source of biodiesel. Biodiesel yields of 91.55%, 77.49%, and 38.69% were obtained for the mixed microbial population, E. cloacae and P. putida. The hydrocarbons obtained from all the microbial cultures were found to have a carbon chain length in the range of C9–C32 and comprised saturated and unsaturated groups, which make them comparable to light oil.
Climate - adaptive anaerobic digestion of food waste in household digesters: insights from extreme temperature conditions
(Elsevier, 2025-06) Raghuvanshi, Smita
Anaerobic digestion (AD) is a widely used method for organic waste treatment, but the energy requirement for temperature control poses challenges, especially for household digesters. This study focuses on the semi-continuous AD process of FW in household digesters at an ambient temperature in Pilani, adjusting organic loading rates (OLR) based on daily temperature fluctuations. Additionally, it assesses ammonium removal efficiency during the degradation of FW using a low-cost magnesite-derived stabilizing agent. The findings highlight the feasibility of generating inoculum from cow dung in anaerobic conditions within a few weeks. The average specific biogas production was 0.591 ± 0.20 m3/kgVS, with a 58 ± 3 % methane concentration. The addition of the stabilizing agent resulted in a 30.3 % increase in biogas production by precipitating struvite, which led to a 22.6 % reduction in total ammonia nitrogen, thereby preventing the inhibition of methanogenic bacteria. Characterization studies, including FTIR, XRF, XRD, and SEM analyses, validate the stabilizing agent's formation and struvite precipitation. However, during a sudden and significant drop in winter temperatures, biogas production decreased to 0.210 ± 0.052 m3/kg VS, with methane content falling to 49 %, highlighting the need for microbial acclimatization. The study indicates that anaerobic digesters can operate effectively at low temperatures with a reduced OLR when the microbial community is adequately acclimatized. Furthermore, the effluent characteristics post-digestion exhibits favorable nitrogen and potassium values, and phosphate recovery through struvite precipitation is evident. Economically, the study demonstrated that replacing non-subsidized LPG with biogas yielded a pay-back period of 6 years and an internal rate of return of 15.6 %. Additionally, the challenges of household biogas production and corresponding potential recommendations are thoroughly addressed. The study highlights the potential of the investigated AD system at ambient conditions, incorporating cost-effective innovations to enhance the efficiency of the process. It provides valuable insights for decision-makers and waste management planners, extending its relevance beyond Pilani to similar settings.
CO2 sequestration potential of halo-tolerant bacterium Pseudomonas aeruginosa SSL-4 and its application for recovery of fatty alcohols
(Elsiever, 2017-10) Jha, Prabhat N.; Mishra, Somesh; Gupta, Suresh; Raghuvanshi, Smita
Bio-mitigation of CO2 utilizing prokaryotes and simultaneous extraction of valuable bio-molecule is fast gaining interest now-a-days. Present work discusses the thermodynamic assessment of CO2 bio-mitigation capability of Pseudomonas aeruginosa SSL-4 isolated from halo alkalophilic habitat in the absence of light. The maximum specific growth (μMax, h−1) of isolate was found to be 0.425 (±0.0025) and 0.34 (±0.0063) at 3% (w/v) salt concentration and 35 °C, respectively. The isolate was cultivated in the environment having initial CO2 (g) concentration of 17(±0.8) % (v/v) using Fe[II] as an energy source (0, 50 and 100 ppm) for evaluating CO2 fixing ability of microorganisms. The maximum CO2 removal efficiency of 92.37 (±2.46) % (v/v) was obtained at 100 ppm of Fe[II] concentration. The isolate has shown the maximum CO2 fixation rate () of 0.04 (±0.003) and 0.06 (±0.001) g/L/d at 50 and 100 ppm of Fe[II] concentration, respectively. FT-IR and GC–MS analysis of obtained leachate revealed the presence of fatty alcohols (C12–C28) and total product recovery (C12–C18) of 0.371 g per g of biomass. The thermodynamic assessment revealed the actual CO2 utilization efficiency of 41.16%. Thus, the isolated strain from extreme hyper saline environment has shown the potential for research dedicated to carbon capture and utilization.
Comparative Study Using Life Cycle Approach for the Biodiesel Production from Microalgae Grown in Wastewater and Fresh Water
(Elsevier, 2018) Sangwan, Kuldip Singh; Raghuvanshi, Smita
Use of bio fuels is a sustainable solution in the current energy scenario, which is marked by unsustainable use of fossil fuels. Production of biodiesel requires microalgae as feedstock. The micro algae require nutrients, CO2 & light source for its growth. An approach where waste water treatment plant can act as source of nutrients for the growth of microalgae would be beneficial. Hence the present work was carried out to understand the life cycle assessment of biodiesel production from microalgae grown in waste water and associated impacts compared with biodiesel production from fresh water. The system boundary considered in the process includes cultivation of microalgae, flocculation, centrifugation, extraction, and transesterification. The functional unit considered for the study is 1 MJ of energy produced from biodiesel. The life cycle assessments (LCA) for the present case was carried out using Umberto NXT software and inventory was taken from Eco invent database v3.0 and literature. Results has shown that the microalgae grown in waste water requires lesser energy as compared to algae grown in fresh water.
A comprehensive review of flue gas bio-mitigation: chemolithotrophic interactions with flue gas in bio-reactors as a sustainable possibility for technological advancements
(Springer, 2024-04) Raghuvanshi, Smita; Gupta, Suresh
Flue gas mitigation technologies aim to reduce the environmental impact of flue gas emissions, particularly from industrial processes and power plants. One approach to mitigate flue gas emissions involves bio-mitigation, which utilizes microorganisms to convert harmful gases into less harmful or inert substances. The review thus explores the bio-mitigation efficiency of chemolithotrophic interactions with flue gas and their potential application in bio-reactors. Chemolithotrophs are microorganisms that can derive energy from inorganic compounds, such as carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur dioxide (SO2), present in the flue gas. These microorganisms utilize specialized enzymatic pathways to oxidize these compounds and produce energy. By harnessing the metabolic capabilities of chemolithotrophs, flue gas emissions can be transformed into value-added products. Bio-reactors provide controlled environments for the growth and activity of chemolithotrophic microorganisms. Depending on the specific application, these can be designed as suspended or immobilized reactor systems. The choice of bio-reactor configuration depends on process efficiency, scalability, and ease of operation. Factors influencing the bio-mitigation efficiency of chemolithotrophic interactions include the concentration and composition of the flue gas, operating conditions (such as temperature, pH, and nutrient availability), and reactor design. Chemolithotrophic interactions with flue gas in bio-reactors offer a potentially efficient approach to mitigating flue gas emissions. Continued research and development in this field are necessary to optimize reactor design, microbial consortia, and operating conditions. Advances in understanding the metabolism and physiology of chemolithotrophic microorganisms will contribute to developing robust and scalable bio-mitigation technologies for flue gas emissions.
A comprehensive study on the behavior of a novel bacterial strain Acinetobacter guillouiae for bioremediation of divalent copper
(Springer, 2015-05-28) Gupta, Suresh; Raghuvanshi, Smita; Majumder, Subhajit
Biological methods have been successfully used to mitigate heavy metal pollution problem in wastewater. The present study was aimed towards isolation of a novel indigenous bacterial strain, Acinetobacter guillouiae from activated sludge and its subsequent application in remediation of copper (Cu2+) from aqueous solution. Kinetic study of bioremediation was performed for initial Cu2+ concentrations ranging from 40 to 150 mg L−1. Optimum values of nutrient dosage, pH, macronutrients [Nitrogen (N)–Phosphorus (P)–Potassium (K)] dosage, aerobic and facultative anaerobic conditions, temperature, and inoculum volume were determined by conducting separate batch bioremediation studies at 80 mg L−1 initial concentration of Cu2+. Kinetic study showed that A. guillouiae removed 98.7 % Cu2+ for 80 mg L−1 initial concentration of Cu2+ after 16 h at an optimum solution pH of 7.0. Results also revealed that A. guillouiae showed maximum growth at double the standard composition of N, P and standard composition of K in nutrient dosage. Experimental data obtained in present study were utilized to validate different growth kinetic models such as Monod, Powell, Haldane, Luong, and Edwards. Growth kinetics of A. guillouiae was better understood by Luong model (R 2 = 0.97). Higher values of coefficient of determination (R 2 = 0.97–0.99) confirmed the suitability of the three-half-order kinetic model for representing the Cu2+ bioremediation. A. guillouiae showed a robust removal mechanism for the bioremediation of Cu2+.
Deducing the Bio-Perspective Capabilities of Fe(II) Oxidizing Bacterium Isolated from Extreme Environment
(BAB, 2015) Jha, Prabhat N.; Mishra, Somesh; Raghuvanshi, Smita; Gupta, Suresh
Rigorous utilization of chemical fertilizers, monoculture and irrigation with surface saline water is globally deteriorating the quality of surface soil. In present work, the halo and alkalo tolarent bacterium strain isolated from extreme environment, was explored for producing plant growth hormones, that could be used for salt stress up gradation of the crops. The 16S rRNA gene sequencing was used for analysis of salt tolerant bacterium. The bacterium was identified as Pseudomonas aeruginosa KP163922. The Pseudomonas aeruginosa KP 163922 showed plant growth promotion traits, production of industrially important enzymes (amylase, protease and cellulase) and tolerance to more than 4% NaCl. The antagonistic test reveals that, the growth of pathogenic gram negative bacterium E. coli and Pseudomonas putida was repressed by Pseudomonas aeruginosa KP163922
Defluoridation studies using graphene oxidebased nanoadsorbents
(Elsevier, 2021) Raghuvanshi, Smita; Gupta, Suresh
The groundwater of many developed and developing countries including India has reported excessive fluoride concentrations. Various technologies are being used to remove fluoride from water but still the problem has remained unsolved. Among the available different technologies, adsorption is one of the best methods due to its easy handling, high efficiency, and lower cost. Adsorption technique with the application of nanoadsorbents has become more efficient, as the adsorption capacity is found to increase significantly due to the large surface area provided by the nanoparticles. Since the last few years, nanomaterial-related technologies have gained much attention in the field of water treatment. The previous studies have discussed the possible mechanism for fluoride ion adsorption on nanoparticles. This chapter discusses the possibility of magnesium oxide nanoparticles as adsorbents for the removal of fluoride from wastewater. This chapter demonstrated the use of modified Hummers' method for synthesizing nano-magnesium oxide (n-MgO) and nanocomposites (n-MgO-coated GOs). The developed adsorbents were characterized using various methods such as FTIR, XRD, SEM-EDX, TEM, etc. The effect of various influencing parameters such as initial pH, initial fluoride concentration, adsorbent dosage, and contact time on fluoride adsorption using developed adsorbents was studied. This chapter demonstrated the efficient removal of fluoride ions from aqueous solution using n-MgO and nanocomposites.
Effect of inoculation of zinc-resistant bacterium Enterobacter ludwigii CDP-14 on growth, biochemical parameters and zinc uptake in wheat (Triticum aestivum L.) plant
(Elsiever, 2018-03) Jha, Prabhat N.; Mishra, Somesh; Raghuvanshi, Smita
A metal resistant bacterium was isolated from the rhizosphere of Kair ‘Capparis decidua’ and screened for its phytoextraction ability under gradient metal stress conditions. Based on 16S rDNA analysis, the strain was identified as Enterobacter ludwigii. Among the plant growth promoting traits, isolate showed the ACC (1-aminocyclopropane-1-carboxylate) deaminase activity, production of indole-3-acetic acid in tryptophan supplemented medium and solubilize the inorganic phosphate. The isolate was resistant to heavy metals like zinc (Zn), nickel (Ni), copper (Cu), and cadmium (Cd). The fatty acid adaptation of isolate growing at different concentration of Zn (100–300 mg kg−1) was also studied, which indicated that metal concentration strongly influenced the fatty acid composition of bacterium, particularly by increasing the unsaturated fatty acids. Furthermore, inoculation with the test isolate was found to significantly (p < 0.01) increase the various growth parameters of wheat plants and also improve the photosynthetic pigments. In addition, inoculation with isolate resulted in significant (p < 0.01) increase in the Zn content in wheat plant under metal stress. Moreover, bacterial application significantly (p < 0.01) increased the various compatible solutes such as proline content (30–65%), total soluble sugar (9–49%), and decreased the malondialdehyde (MDA) content (38–47%) as compared to control, illustrating its protective effect under metal induced oxidative stress. Inoculation with test isolate also increased the total protein content in range of 16–52%. Our work revealed that metal resistant plant growth promoting rhizobacterium could be exploited as microbial mediated phytoremediation of metal polluted soils.