Browsing by Author "Yogalakshmi K.N."

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Batch fed single chambered microbial electrolysis cell for the treatment of landfill leachate
(Elsevier Ltd, 2020) Rani G.; Nabi Z.; Rajesh Banu J.; Yogalakshmi K.N.
A fed batch membraneless microbial electrolysis cell (MEC) was investigated for treating combined leachate and dairy wastewater at an applied voltage 0.8 V and hydraulic retention time (HRT) of 48 h. The COD (chemical oxygen demand) removal and energy recovery was tested by running several cycles of MEC with increasing ratios of leachate to dairy wastewater. With an increase in percentage of simulated leachate, MEC performance in terms of current generation, COD removal efficiency and hydrogen production showed a gradual decrease. A sudden drop in reactor performance was noticed when the concentration of leachate was increased from 14 to 16% corresponding to an increase in Organic Load Rate (OLR) from 23.89gCOD/m3/d to 24gCOD/m3/d. A continued operation of MEC at an OLR of 24gCOD/m3/d for ten continuous cycles resulted in COD removal efficiency of 73% and hydrogen production of 15 mL/L/d with current density of 10 A/m2 and a power density of 80 mW/cm2.
Biohythane production from food processing wastes – Challenges and perspectives
(Elsevier Ltd, 2020) Meena R.A.A.; Rajesh Banu J.; Yukesh Kannah R.; Yogalakshmi K.N.; Kumar G.
The food industry generates enormous quantity of food waste (FW) either directly or indirectly including the processing sector, which turned into biofuels for waste remediation. Six types of food processing wastes (FPW) such as oil, fruit and vegetable, dairy, brewery, livestock and finally agriculture based materials that get treated via dark fermentation/anaerobic digestion has been discussed. Production of both hydrogen and methane is daunting for oil, fruit and vegetable processing wastes because of the presence of polyphenols and essential oils. Moreover, acidic pH and high protein are the reasons for increased concentration of ammonia and accumulation of volatile fatty acids in FPW, especially in dairy, brewery, and livestock waste streams. Moreover, the review brought to forefront the enhancing methods, (pretreatment and co-digestion) operational, and environmental parameters that can influence the production of biohythane. Finally, the nature of feedstock's role in achieving successful circular bio economy is also highlighted.
Control of sludge microbial biofilm by novel quorum quenching bacteria Pseudomonas nitroreducens JYQ3 and Pseudomonas JYQ4 encapsulated sodium alginate - Magnetic iron nanocomposites
(Elsevier Ltd, 2018) Kaur J.; Yogalakshmi K.N.
Biofouling control via quorum quenching (QQ) approach is becoming popular among other fouling mitigation strategies. In the present study, the mitigation of membrane biofouling problem via disruption of cell-to-cell communication was studied by immobilizing QQ bacteria in sodium alginate magnetic nanocomposite beads. Two QQ bacteria viz. Pseudomonas nitroreducens JYQ3 and Pseudomonas JYQ4 isolated from dairy waste activated sludge was immobilized individually into the beads. Scanning electron microscopy (SEM) analysis revealed the successful immobilization of QQ bacteria into the alginate nanoparticle beads. The Confocal laser scanning microscopy (CLSM) results provided evidence of biofouling controlled activities of Pseudomonas nitroreducens JYQ3 and Pseudomonas JYQ4 immobilized nanocomposite (IMN) beads. Further, the membranes incubated with Pseudomonas nitroreducens JYQ3 and Pseudomonas JYQ4 IMN beads showed better flux (19% and 22% higher, respectively) than the control. Hence, the results revealed that the QQ bacteria IMN beads would be an efficient approach for controlling the biofilm developed on the cellulose acetate membrane surface.
Degradation of chlorpyrifos in soil using laccase immobilized iron oxide nanoparticles and their competent role in deterring the mobility of chlorpyrifos
(Elsevier Ltd, 2020) Das A.; Jaswal V.; Yogalakshmi K.N.
Covalent-immobilization of the laccase enzyme onto the iron oxide nanoparticles was achieved using N-(3-Dimethylaminopropyl)-N?-ethylcarbodiimide hydrochloride (EDAC) as cross-linkers. The presence of sulphur moeity in the laccase immobilized nanoparticles (LNPs) observed through Scanning Electron Microscopy- Energy dispersive X-ray spectroscopy (SEM-EDS) spectra confirmed the immobilization of laccase enzyme. The TEM analysis of iron oxide nanoparticles (FNPs), chitosan coated iron nanoparticles (CNPs) and laccase immobilized nanoparticles (LNPs) confirmed their sizes around 12, 15 and 20 nm, respectively. The effect of LNPs in degrading chlorpyrifos under field conditions was studied by simulating the conditions in a column. Column A, which was used as control showed more leaching of chlorpyrifos as compared to column B containing LNPs. The sorption coefficient (Kd) value obtained for control (column A) and LNPs containing column B were 21.6 and 112.3 L/kg, respectively. LNPs altered the Kd values of soil thereby showing lesser leaching potential. Higher the Kd value, lesser will be the leaching potential in the ground water. Copper in laccase enzyme resulted in hydrolysis of chlorpyrifos. Chitosan used for coating on FNPs and soil organic matter resulted in the adsoption of chlorpyrifos. Current results will allow a better assessment of the role of LNPs as a competent deterrent in chlorpyrifos mobility and degradation.
Screening of quorum quenching activity of the bacteria isolated from dairy industry waste activated sludge
(Center for Environmental and Energy Research and Studies, 2019) 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%.