Browsing by Author "Yogalakshmi, K.N."

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Anode modification: An approach to improve power generation in microbial fuel cells (MFCs)
(Elsevier, 2023-01-27T00:00:00) Rani, Gini; Jaswal, Vijay; Yogalakshmi, K.N.
Global energy demand is continuously increasing and has become a matter of concern. At present, 86% of the energy demand are accomplished by fossil fuels, but these deliver harmful effects on the environment by releasing CO2 in the atmosphere. Contrary, though nonrenewable resources such as solar, wind, and bioenergy possess minimal carbon footprints, they suffer from limitations of higher installation cost, low efficiency, and complex operation system. Since the past two decades, a relatively new sustainable technology, the microbial fuel cells (MFCs) have emerged with potential to convert the bond energy of molecules present in organic/inorganic waste into electric energy with the help of microbes. The electricity produced through the release of electrons during microbial degradation of organic waste can be used to offset the running cost of wastewater treatment plants. The performance of the MFCs is influenced by a number of cofactors, viz. type of reactor, nature of feed, microbial consortia, electrode material, and mode of operation. Anode plays a significant role in the power enhancement. Across the globe, various research groups are working to enhance the efficiency and power output of anode through its modification using conductive polymers (polypyrrole and polyaniline), metal oxides, nanomaterials, and many others. MFC operated with the electrochemically reduced graphene oxide modified anode evidenced a power density enhanced by 17.5 times as compared to carbon cloth. In the past 5 years, power density ranging from 6.12 to 6119mWm?2 was observed with various modified anode. The chapter will throw light on anode materials popularly used in MFC, method/techniques used for its modification to enhance energy output and limitations that restrict its wide-scale application. � 2023 Elsevier Inc. All rights reserved.
Biofiltration in wastewater treatment plants: An overview
(Elsevier, 2022-01-15T00:00:00) Yogalakshmi, K.N.; Sharma, Avimanu; Mittal, Sunil
Biofilters or biological filters are a technology that uses attached biomass on a media to degrade and remove pollutants from the air, water, and wastewater treatment plants. They are natural systems which are engineered and simulated to remove a varied range of contaminants, that is, organic matter, suspended solids, natural organic matter, and organic micropollutants. Biofiltration systems are popular among wastewater treatment process due to its simple operation, robust nature, and low energy requirement. Trickling filters, aerated biological filters, and membrane bioreactors are some of the popular biofiltration systems used for wastewater treatment. The efficiency of the biofiltration systems depends on the nature, composition, and community structure of microorganisms in the biofilm developed on the medium. Immobilized biofilters are also popular in wastewater treatment. This chapter would provide an overview on the concept of biofiltration, the mechanism involved, types, and application of biofiltration process. The chapter will also throw light on the microbial ecology and community structure of the biological filters. Further, the different methods of identification of the microbial community will also be discussed in the chapter. � 2022 Elsevier Inc.
Degradation of n-hexanoyl homoserine lactone with quorum quenching bacteria immobilised magnetic nanocomposite beads
(Taylor and Francis Ltd., 2020-08-20T00:00:00) Kaur, Jaskiran; Yogalakshmi, K.N.
N-acyl homoserine lactones (AHLs) based quorum sensing controls various phenotype expressions, including biofilm formation, hence its interruption is considered to be an ideal option for membrane biofouling control. Bead entrapped quorum quenching bacteria was reported to be an efficient approach for degradation of signal molecules in recent years. In the present study, we investigated the potential of quorum quenching (QQ) bacteria immobilised magnetic nanocomposite beads (IMN) in degradation of signalling molecule, n-hexanoyl homoserine lactone (C6-HSL). Three QQ bacteria, named Acinetobacter baumannii JYQ2, Pseudomonas nitroreducens JYQ3 and Pseudomonas JYQ4 isolated from dairy industry waste activated sludge (WAS) were immobilised in the magnetic nanocomposite (IMN) beads. The scanning electron microscopy (SEM) of the IMN beads has indicated the successful entrapment of QQ bacteria within the alginate matrix. The GC-MS analysis showed that all the QQ bacteria immobilised magnetic nanocomposite (IMN) beads degraded the signalling molecule, n-hexanoyl homoserine lactone (C6-HSL) within 72 h of incubation. The nanocomposite beads containing the QQ bacteria Pseudomonas JYQ4 showed the maximum degradation percentage of 97 � 0.13% leaving a residual HSL of 0.7 mg/L. All the other isolates showed C6-HSL degradation percentage in the range of 87% to 95%. The data suggest the potential of C6-HSL degradation by QQ bacteria IMN beads. Hence, the study offers possibilities of controlling biofilm developed on the membrane surface during wastewater treatment processes. � 2020 Informa UK Limited, trading as Taylor & Francis Group.
Effect of chemo-mechanical disintegration on sludge anaerobic digestion for enhanced biogas production
(Springer Verlag, 2016) Kavitha, S.; Saji Pray, S.; Yogalakshmi, K.N.; Adish Kumar, S.; Yeom, I.-T.; Rajesh banu, J.
The effect of combined surfactant-dispersion pretreatment on dairy waste activated sludge (WAS) reduction in anaerobic digesters was investigated. The experiments were performed with surfactant, Sodium dodecyl sulfate (SDS) in the range of 0.01 to 0.1?g/g suspended solids (SS) and disperser with rpm of 5000?25,000. The COD (chemical oxygen demand) solubilization, suspended solids reduction, and biogas generation increased for an energy input of 7377?kJ/kg total solids (TS) (12,000?rpm, 0.04?g/g SS, and 30?min) and were found to be 38, 32, and 75?%, higher than that of control. The pretreated sludge improved the performance of semicontinuous anaerobic digesters of 4?L working volume operated at four different SRTs (sludge retention time). SRT of 15?days was found to be appropriate showing 49 and 51?% reduction in SS and volatile solids (VS), respectively. The methane yield of the pretreated sample was observed to be 50?mL/g VS removed which was observed to be comparatively higher than the control (12?mL/g VS removed) at optimal SRT of 15?days. To the best of the authors? knowledge, this study is the first to be reported and not yet been documented in literature. ? 2015, Springer-Verlag Berlin Heidelberg.
Effect of enzyme secreting bacterial pretreatment on enhancement of aerobic digestion potential of waste activated sludge interceded through EDTA
(Elsevier Ltd, 2013) Kavitha, S.; Adish Kumar, S.; Yogalakshmi, K.N.; Kaliappan, S.; Rajesh Banu, J.
In this study, the effect of Ethylene diamine tetra acetic acid (EDTA) on Extracellular polymeric substance (EPS) removal tailed with bacterial enzymatic pretreatment on aerobic digestion of activated sludge was studied. In order to enhance the accessibility of sludge to the enzyme secreting bacteria; the extracellular polymeric substances were removed using EDTA. EDTA efficiently removed the EPS with limited cell lysis and enhanced the sludge enzyme activity at its lower concentration of 0.2. g/g SS. The sludge was then subjected to bacterial pretreatment to enhance the aerobic digestion. In aerobic digestion the best results in terms of Suspended solids (SS) reduction (48.5%) and COD (Chemical oxygen demand) solubilization (47.3%) was obtained in experimental reactor than in control. These results imply that aerobic digestion can be enhanced efficiently through bacterial pretreatment of EPS removed sludge. ? 2013 Elsevier Ltd.
Effect of organic loading rate on electricity generating potential of upflow anaerobic microbial fuel cell treating surgical cotton industry wastewater
(Elsevier Ltd, 2017) Tamilarasan, K.; Banu, J.R.; Jayashree, C.; Yogalakshmi, K.N.; Gokulakrishnan, K.
In this study, the performance of continuous fed upflow anaerobic microbial fuel cell operated with surgical cotton industry wastewater was investigated at different Organic Loading Rate (OLR). The potency of power generation, COD and TSS removal efficiency was determined. The highest TCOD and SCOD removal of 78.8% and 69%, respectively was accomplished at an optimum OLR of 1.9 gCOD/L d. A 62% TSS removal efficiency was obtained, with an initial TSS concentration of wastewater as 970 ? 70 mg/L. The maximum power density 116.03 mW/m2 (2.2 W/m3) and corresponding coulombic efficiency of 17.8% was achieved at the OLR of 1.9 gCOD/L/d while treating surgical cotton industry waste water. ? 2017 Elsevier Ltd.
Electrode modification and its application in microbial electrolysis cell
(Elsevier, 2022-02-04T00:00:00) Rani, Gini; Banu, J. Rajesh; Yogalakshmi, K.N.
The microbial electrolysis cell (MEC) is a sustainable technology that degrades organic substrate to produce hydrogen, an important energy carrier. However, its large-scale practical application is hampered because of several factors including electrodes material, reactor designs, substrates, and high-cost catalysts. Electrodes in particular are fundamental components which determine redox reaction and transport of electric charge. The surface of the electrode is where the equilibrium of redox reaction is established between the electrode surface and the electrolyte (substrate). Therefore, modification of electrodes is emphasized much recently. Modified electrodes have wide application as electrochemical devices, chemical analysis, biosensors, and many more. The electrode modification is carried out to bring improved properties in the electrode by altering its morphology or molecular structure. Apart from high conductivity and low resistance, the modified electrodes develop increased sensitivity, selectivity, corrosion resistance, electrochemical, and chemical stability. They also possess large potential window. Moreover, electrode modification using nanomaterials and conductive polymers favors electrocatalysis process. Studies related to MEC using modified electrodes have reported improved wastewater treatment and hydrogen production along with enhanced energy recovery. In the present chapter, the mechanics of electrode in an electrochemical system, in general, is explained in detail. Moreover, the overview of different techniques for the modification of the electrodes and their applications in MEC has been expensively entailed. � 2022 Elsevier Inc.
Enhancing the electrochemical performance of Fe3O4 nanoparticles layered carbon electrodes in microbial electrolysis cell
(Elsevier Ltd, 2021-09-10T00:00:00) Rani, Gini; Krishna, Kadirvelu; Yogalakshmi, K.N.
The present study assesses the performance of microbial electrolysis cell (MEC) to generate electric current using (I) uncoated/untreated electrodes and (II) Fe3O4 nanoparticles (FNPs) coated electrodes. The cyclic voltammetry (CV) reports highest conductivity of 58 Sm?1 in (II) while lowest (0.18 Sm?1) in (I) electrodes. The impedance spectroscopy confirms bulk resistivity of 375 k? in (I) electrodes while relatively lowest resistivity of 0.4 k? in (II) electrodes. Two sets of single chamber membraneless MECs is operated simultaneously at different applied voltage (300 mV, 500 mV and 700 mV): RI (uncoated electrodes) and RII, (FNP coated electrodes). The RII attains maximum current density and power density of 15.2 mAcm?1 and 10.6 mWcm?2 respectively at 0.7 V while RI achieves the maximum current density and power density of 4.03 mAcm?2 and 2.8 mWcm?2 respectively at same voltage. Moreover, the current density recorded in electrodes (II) is significantly higher compared to electrodes (I) measured using CV. The result suggests FNP to be an excellent catalyst which improves biosynthesis of electric current. The biologically active environment consisting of anaerobic electrogenic microbes supported biosynthesis/generation of high electric current along with other metabolites produced from the microbes mediated redox reaction. � 2021 Elsevier Ltd
Enzyme assisted biodegradation of chloropyrifos pesticide: A mini review
(2013) Anamika; Yogalakshmi, K.N.
Graphitic carbon nitride for photocatalytic CO2 reduction. Energy and Air Pollution.
(Elsevier, 2022-01-15T00:00:00) Teja, Y.N.; Sakar, M.; Yogalakshmi, K.N.
Among the various emerging photocatalytic materials, graphitic carbon nitride (g-C3N4) has gained significant importance due to their two-dimensional (2D) structure, promising electronic, optical, and interfacial properties. The features such as narrow band gap energy, reduced recombination process, enhanced transportation of charge carriers to the surrounding, and appropriate band edge potential to produce the required redox species are making the g-C3N4 as a promising candidate for various photocatalytic applications, especially for CO2 reduction into hydrocarbon fuels. It should be noted that the CO2 conversion essentially involves two simultaneous process known as the CO2 reduction and protonation. The effectiveness in such simultaneous process requires the appropriate positioning of band edge potential in the system, which can be effectively engineered in g-C3N4-based materials as compared to the other metal oxide-based systems. Interestingly, in addition to the chemical induced redox process, the CO2 conversion properties of g-C3N4 can also be attributed to their physical structures such as 2D layers and porous structures, where it causes the shifting of band edge positions and enhanced CO2 adsorption in g-C3N4. To this end, this chapter provides a glimpse of structure-property relationship of g-C3N4 based materials towards their photocatalytic CO2 conversion properties, where it discusses the various g-C3N4 material systems and their efficiency towards the conversion of CO2 into various hydrocarbon fuels under light visible light/sunlight irradiations. � 2022 Elsevier Inc. All rights reserved.
An Insight into Biological Photovoltaic Cell Based Electrochemical System
(Springer Singapore, 2021-02-02T00:00:00) Rani, Gini; Jaswal, Vijay; Banu, Rajesh; Yogalakshmi, K.N.
Biological photovoltaic cells can be called as living solar cells. They use oxygenic photoautotrophs such as cyanobacteria and algae, instead of silicon, to capture light energy for photolysis. The organisms such as cyanobacteria and algae capture light energy during the process of photosynthesis and perform charge separation of water molecules (photolysis), producing protons, electrons, and oxygen molecules. The electrons thus produced are transferred to the anode and through external circuit they move to cathode to get reduced to water, producing electric current. Biophotovoltaic (BPV) are different from traditional silicon based solar photovoltaics (SPV) cells in a number of ways. Unlike SPV, the presence of water is imperative in BPV for the algae/cyanobacteria to perform photolysis. The BPV are self-renewing in nature and do not require any external carbon source for growth. The technology of BPV can be incorporated in bioelectrochemical systems (BES) to generate green energy. BPV based electrochemical technology can be used as solar bio-battery or bio-solar panel. It can also be utilized in low powered devices such as alarm clocks. Despite the multiple advantages of BPV, still they are in the threshold of its development due to its energy conversion efficiency. The chapter would comprehensively explain the principle, working, and application of biological photovoltaic systems. � Springer Nature Singapore Pte Ltd. 2020.
Isolation of indigenous butachlor (Herbicide) degrading bacteria from the agricultural fields of punjab
(Central University of Punjab, 2014) Singh, Jatinder; Yogalakshmi, K.N.
Butachlor (N-Butoxymethyl-2-chloro-2', 6'-diethyl acetanilide) is a chloroacetalanilide herbicide widely used in paddy fields. Due to extensive application, high stability and persistence in soil and water, has resulted in its ubiquitous presence as a pollutant. Hence, it becomes necessary to degrade the herbicide through an eco friendly and cost effective method. In this study, the degradation of butachlor herbicide was studied under controlled laboratory condition. The soil was collected from the agricultural fields of Punjab. The inoculum from the soil was enriched in 0.16mmol/L of butachlor at 130 rpm and 30 ?C. The enriched culture was plated and the best growing bacteria was isolated and designated as JF. The biodegradation of strain JF was evaluated at 0.16 and 0.32mmol/L concentration of butachlor. The isolate showed a degradation efficiency of 91.87% and 78.08% at 0.16mmol/L and 0.32mmol/L of butachlor, respectively in 120 hours (pH 7). The bacterial isolate JF was identified as Staphylococcus sp. through biochemical characterization. This study highlights the first report of isolation of butachlor degrading bacteria from the native soil of Punjab.
Laccase enzyme and its role in degradation of pesticide – A mini review
(2013) Anamika; Yogalakshmi, K.N.
Laccase immobilized magnetic iron nanoparticles: Fabrication and its performance evaluation in chlorpyrifos degradation
(Elsevier Ltd, 2017) Das, A.; Singh, J.; Yogalakshmi, K.N.
Chlorpyrifos degradation was studied using laccase immobilized on magnetic iron nanoparticles (CENPs). The magnetic iron nanoparticles (MNPs) prepared by co-precipitation method were characterized using Transmission electron microscopy (TEM), Scanning electron microscopy- Energy dispersive spectroscopy (SEM-EDS) and Thermogravimetric analysis (TGA). The size of the nanoparticles ranged between 10 and 15 nm. The MNPs were coated with chitosan, surface modified with carbodiimide (EDAC) immobilized with laccase enzymes. The chlorpyrifos degradation studies were performed in batch studies under constant shaking for a period of 12 h. Results of the study showed that laccase immobilized on magnetic iron nanoparticles were effective in degrading more than 99% chlorpyrifos in 12 h at pH 7 and 60 ?C. In the overall degradation percentage, MNPs contributed to 32.3% of chlorpyrifos removal while ENPs resulted in 58.8% chlorpyrifos degradation. Immobilization of enzyme decreased the overall activity of the free enzyme. The CENPs showed 95% activity after five repeated washing and hence possess good reusability potential. ? 2017 Elsevier Ltd
Optimization of Copper (II) Removal by Response Surface Methodology Using Root Nodule Endophytic Bacteria Isolated from Vigna unguiculata
(Springer International Publishing, 2016) Manohari, R.; Yogalakshmi, K.N.
The present study was conducted to investigate copper tolerance and bioremediation potential in endophytic bacteria isolated from Vigna unguiculata root nodules. Total ten endophytes were isolated on yeast mannitol agar and enriched in copper (II) sulfate (CuSO4) up to 500?mg/L. Four endophytes belonging to genera Bacillus and Arthrobacter showed copper tolerance. The isolates were identified as Arthrobacter tumbae MYR1, Bacillus safensis MYR2, Bacillus pumilus MYR3 and Bacillus sp. MYR4 using 16S ribosomal RNA (rRNA) analysis. Response surface methodology was used for copper (II) removal optimization. The model was significant with R2, P and F value of 0.9780, <0.0001, and 34.54, respectively. Results showed that highest copper (II) bioremoval of 82.8?% was obtained at pH 5.0, temperature 32.5??C, and 600?mg/L copper concentration after 168?h of incubation. The isolates were tested for plant growth promotion and all the strains produced indole acetic acid (IAA) and showed 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. The study concludes that endophytic bacteria possessed greater potential for copper tolerance and bioremediation. ? 2016, Springer International Publishing Switzerland.
Performance of magnetic iron nanoparticle decorated electrodes single chambered MEC fed with combined leachate and dairy industry wastewater
(Central University of Punjab, 2017) Deepika; Yogalakshmi, K.N.
Increased human activity and consumption of natural energy resources have led to decline in the stock of fossil fuels. The current technologies used for energy generation are not environment friendly. Microbial electrolysis cell (MEC) represents a new approach for harnessing the energy contained in the organic matter of wastewater. It is a type of bioelectrochemical systems in which chemical energy stored in organic compounds are converted to biogas such as hydrogen through biocatalytic oxidation by microorganisms. But it still suffers from the lack of efficiency in terms of hydrogen production and current generation. Previous studies have demonstrated that the electrodes coated with nanoparticles such as Fe, Au, Pd, and Ni nanoparticles have the potential to enhance energy recovery in MEC. Hence, the present study aims to use single chambered membrane-less microbial electrolysis cell with magnetic iron nanoparticle coated electrodes for treating combined leachate and dairy industry wastewater. The performance of the MEC was assessed through COD removal, current and biogas generation at an applied voltage of 0.8 V and HRT of 48 hours. Results demonstrated that the maximum current density achieved by nanoparticles decorated electrodes was 3.86 times higher than iv generated by plain electrodes. The highest COD removal efficiency of 96.5% was achieved at OLR equal to 17.14 gCOD/L/d. The maximum coulombic efficiency of 155% represents the conversion of maximum chemical energy stored in the combined wastewater into electrical energy. The hydrogen production rate of 3.192 L/L/d was achieved in this study. The results shows that magnetic iron nanoparticle coated electrodes enhance the current generation and COD removal in single chambered MEC operated with combined leachate and dairy wastewater treatment.
Photosynthetic Microbial Fuel Cells: From Fundamental to Potential Applications
(Springer Singapore, 2021-02-09T00:00:00) Jaswal, Vijay; Rani, Gini; Yogalakshmi, K.N.
In photosynthetic microbial fuel cell (MFC), algae and photosynthetic bacteria undergo photosynthesis to generate electricity by harnessing the solar energy. The microorganisms on absorbing solar energy initiate a series of reactions to generate protons (H+ ions), electron, and oxygen through splitting of water. The energy from these reaction series is harnessed by placing photosynthetic organisms in anodic chamber separated from cathodic chamber by a semipermeable membrane selective for hydrogen ions. The electrons generated in an anodic chamber by photosynthetic activity of microbes travel through an outer circuit to the cathodic chamber, where they combine with protons and oxygen at the reductive electrode (cathode) to generate water. This technology has huge potential for converting solar energy into electrical energy and might also help to reduce the carbon footprint. The chapter discusses the concept, fundamentals, process design and operation of photosynthetic MFC. Furthermore, the role of photosynthetic organisms in MFC, various bottlenecks faced by MFC systems and their potential applications are also outlined in the chapter. � Springer Nature Singapore Pte Ltd. 2020.
Phylogenetic analysis of viral protein 2 of blue tongue virus
(New Delhi Publisher, 2016) Prajapati, Leena; Yogalakshmi, K.N.; Kulharia, Mahesh
Phylogenetic analysis of viral protein 2 of blue tongue virus
Polyelectrolyte modificaion of microfiltration for removal of arsenic lons
(Central University of Punjab, 2017) Bala, Bindu; Yogalakshmi, K.N.
Increased human activity and consumption of natural energy resources have led to decline in the stock of fossil fuels. The current technologies used for energy generation are not environment friendly. Microbial electrolysis cell (MEC) represents a new approach for harnessing the energy contained in the organic matter of wastewater. It is a type of bioelectrochemical systems in which chemical energy stored in organic compounds are converted to biogas such as hydrogen through biocatalytic oxidation by microorganisms. But it still suffers from the lack of efficiency in terms of hydrogen production and current generation. Previous studies have demonstrated that the electrodes coated with nanoparticles such as Fe, Au, Pd, and Ni nanoparticles have the potential to enhance energy recovery in MEC. Hence, the present study aims to use single chambered membrane-less microbial electrolysis cell with magnetic iron nanoparticle coated electrodes for treating combined leachate and dairy industry wastewater. The performance of the MEC was assessed through COD removal, current and biogas generation at an applied voltage of 0.8 V and HRT of 48 hours. Results demonstrated that the maximum current density achieved by nanoparticles decorated electrodes was 3.86 times higher than iv generated by plain electrodes. The highest COD removal efficiency of 96.5% was achieved at OLR equal to 17.14 gCOD/L/d. The maximum coulombic efficiency of 155% represents the conversion of maximum chemical energy stored in the combined wastewater into electrical energy. The hydrogen production rate of 3.192 L/L/d was achieved in this study. The results shows that magnetic iron nanoparticle coated electrodes enhance the current generation and COD removal in single chambered MEC operated with combined leachate and dairy wastewater treatment.
Screening of quorum quenching activity of the bacteria isolated from dairy industry waste activated sludge
(Center for Environmental and Energy Research and Studies, 2018) Kaur, J.; Yogalakshmi, K.N.
Intercellular bacterial communication process via exchange of signalling molecules acyl homoserine lactone results in various group activities like bioluminescence, antibiotic production, biofilm formation, sporulation, and virulence. The signalling molecules are targeted, and the communication is interrupted by a group of bacteria termed quorum quenching bacteria. The present study aims to isolate the quorum quenching bacteria from the waste activated sludge collected from the dairy industry effluent treatment plant and explore for its quorum quenching potential. The bacteria were cultured in the KG medium containing n-hexanoyl homoserine lactone as a sole source of carbon and nitrogen. The isolates were identified by the 16S ribosomal deoxyribonucleic acid analysis and subsequently were evaluated for its quorum quenching activity through Chromobacterium violaceum CV026 biosensor assay. The n-hexanoyl homoserine lactone degradation was quantified by GC–MS analysis. The 16S ribosomal deoxyribonucleic acid analysis revealed the isolated bacteria as Klebsiella pneumoniae (JYQ1 and JYQ5), Acinetobacter baumannii JYQ2, Pseudomonas nitroreducens JYQ3, and Pseudomonas JYQ4. The biosensor strain assay and GC–MS analysis indicated that all the isolates possessed an inherent ability to degrade N-hexanoyl homoserine lactone. The strain Pseudomonas JYQ4 exhibited the highest quorum quenching activity of 84 ± 3.3% within 6 h of incubation. The strain A. baumannii JYQ2 acted both as quorum sensing and as quorum quenching bacteria as evidenced by the decrease in quorum quenching from 79 ± 3.1 to 76.8 ± 2.5%.