Disperser-induced bacterial disintegration of partially digested anaerobic sludge for efficient biomethane recovery

Banu, J. Rajesh,Kannah, R. Yukesh,Kavitha, S.,Gunasekaran, M.,Yeom, Ick Tae,Kumar, Gopalakrishnan Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.347 No.-

<P><B>Abstract</B></P> <P>The present study highlights the options to enhance the methane potential of partially digested anaerobic sludge using disperser-induced bacterial disintegration. Floc dispersion with no biomass disintegration was achieved at a disperser-specific energy input of 9.5 kJ/kg TS. The outcomes of both sole bacterial disintegration (S-BD) and disperser-induced bacterial disintegration (D-BD) were assessed in terms of changes in lysate, biopolymer release and increase in biodegradability and methane generation. A higher lysate solubilization of about 22.4% was achieved in D-BD compared to S-BD (11.3%), indicating the efficiency of floc dispersion prior to bacterial disintegration. The biochemical methane result implies that D-BD shows higher methane potential of 0. 279 gCOD/gCOD. Considering the overall outcome achieved in this study, disperser-induced bacterial disintegration is proved to be an effective disintegration process for enhanced biodegradation and higher methane production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Disintegration of digested sludge is a promising technique for bioenergy generation. </LI> <LI> Floc dispersion was achieved at lesser disperser input energy of 9.5 kJ/kg TS. </LI> <LI> A higher lysate solubilization of 22.4% was achieved in floc dispersed sample. </LI> <LI> Biopolymer release of floc dispersed sludge was higher (1379.8 and 394.2 mg/L) </LI> <LI> Result of methane reveals the effect of floc dispersion prior to disintegration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis and Antimicrobial Activity of 1-Benzhydryl-sulfonyl-4-(3- (piperidin-4-yl) propyl)piperidine Derivatives against Pathogens of Lycopersicon esculentum: A Structure-activity Evaluation Study

K. Vinaya, R. Kavitha,C. S. Ananda Kumar,S. B. Benaka Prasad,S. Chandrappa,S. A. Deepak,S. Nanjunda Swamy,S. Umesha,K. S. Rangappa 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.1

Several 1-benzhydryl-sulfonyl-4-(3-(piperidin-4-yl)propyl)piperidine derivatives 8(a-j) were prepared by the treatment of substituted benzhydryl chlorides with 4-(3-(piperidin-4-yl)propyl)piperidine followed by N-sulfonation with sulfonyl chlorides in the presence of dry methylene dichloride and triethyl amine. The synthesized compounds were characterized by 1H-NMR, IR, and elemental analysis. All the synthesized compounds were evaluated in vitro for their efficacy as antimicrobial agents by artificial inoculation technique against standard strains of two important bacterial viz., Xanthomonas axonopodis pv. vesicatoria and Ralstonia solanacearum as well as and two fungal pathogens namely Alternaria solani and Fusarium solani of tomato plants. We have briefly investigated the structure-activity relation studies and reveal that the nature of substitutions on benzhydryl ring and sulfonamide ring influences the antibacterial activity. Among the synthesized new compounds 8b, 8d, 8g, 8h, 8i, and 8j were showed significant potent antimicrobial activities compared to the standard drugs Chloramphenicol, Mancozeb.

Enhancement of biogas production from microalgal biomass through cellulolytic bacterial pretreatment

Kavitha, S.,Subbulakshmi, P.,Rajesh Banu, J.,Gobi, Muthukaruppan,Tae Yeom, Ick Elsevier 2017 Bioresource technology Vol.233 No.-

<P><B>Abstract</B></P> <P>Generation of bioenergy from microalgal biomass has been a focus of interest in recent years. The recalcitrant nature of microalgal biomass owing to its high cellulose content limits methane generation. Thus, the present study investigates the effect of bacterial-based biological pretreatment on liquefaction of the microalga <I>Chlorella vulgaris</I> prior to anaerobic biodegradation to gain insights into energy efficient biomethanation. Liquefaction of microalgae resulted in a higher biomass stress index of about 18% in the experimental (pretreated with cellulose-secreting bacteria) vs. 11.8% in the control (non-pretreated) group. Mathematical modelling of the biomethanation studies implied that bacterial pretreatment had a greater influence on sustainable methane recovery, with a methane yield of about 0.08 (g Chemical Oxygen Demand/g Chemical Oxygen Demand), than did control pretreatment, with a yield of 0.04 (g Chemical Oxygen Demand/g Chemical Oxygen Demand). Energetic analysis of the proposed method of pretreatment showed a positive energy ratio of 1.04.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microalgal biomass pretreatment by bacteria enhances liquefaction of about 18%. </LI> <LI> Bacterial pretreatment increases the macromolecular release considerably. </LI> <LI> Experimental microalgae improves the methane to 0.08gCOD/gCOD comparing to control. </LI> <LI> Methane production rate increased with hydrolysis constant of about 0.24day<SUP>−1</SUP>. </LI> <LI> A positive energy ratio of about 1.04 was achieved in experimental microalgae. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Super-hydrophobicity: Mechanism, fabrication and its application in medical implants to prevent biomaterial associated infections

Kavitha Sri A.,Deeksha P.,Deepika G.,Nishanthini J.,Hikku G.S.,Antinate Shilpa S.,Jeyasubramanian K.,Murugesan R. 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

In this report, the insights for mimicking the natural phenomenon found in lotus leaves i.e. super-hydrophobic surface are compiled. Recently, there are reports that critically evaluated the application ofthis nature inspired property to many artificial substrates like metals, plastics, fabrics, paper, etc. Fromthe summarized reports, it is evident that the two important prerequisites for fabricating super-hydrophobic surfaces are necessary nano/micron scale topographical roughness and subsequentmodification by the low surface energy compounds. Detailed description about the water repellentnature, rolling-off properties of the water droplet with the nano/micro engineered surfaces in terms ofWenzel and Cassie-Baxter models are explored. Extending this application in the biotechnologicalfield asimplants is an innovative thought since employing the non-wettable character in the implants surfacecan eliminate many drawbacks. More thoughts and insights have been focused on developing super-hydrophobicity over bio-materials to reduce bacterial biofilm formation to overcome the drawback ofbiomaterial associated infections. The possible mechanisms behind the biofilm formation and how thesuper-hydrophobic surface can effectively mitigate the bacterial adhesion are also covered in detail.

Impact of thermo-chemo-sonic pretreatment in solubilizing waste activated sludge for biogas production: Energetic analysis and economic assessment

Kavitha, S.,Rajesh Banu, J.,Subitha, G.,Ushani, U.,Yeom, I.T. Elsevier Applied Science 2016 Bioresource technology Vol.219 No.-

The objective of this study was to determine the impact of solubilization during thermo-chemo-sonic pretreatment of waste activated sludge (WAS) on anaerobic biodegradability and cost for biogas production. The results revealed that it was possible to achieve 40-50% of solubilization of WAS when ultrasonic energy input was doubled (11,520-27,000kJ/kgTS). The cost to achieve 30-35% of solubilization of WAS was calculated to be 0.22-0.24USD/L, which was relatively lower than the cost of 0.53-0.8USD/L when 40-50% of solubilisation of WAS was achieved. There was no significant difference in biodegradability (0.60-0.64gCOD/gCOD) for samples with solubilization efficiency of 35-50%. Comparing energetic balance and economic assessment of samples with different solubilization percentages, the results showed that samples with 30-35% of solubilization had lower net cost (7.98-2.33USD/Ton of sludge) and negative energy balance compared to samples with other percentages of solubilization.

Seismic behavior of steel and sisal fiber reinforced beam-column joint under cyclic loading

S.M. Kavitha,G. Venkatesan,Siva Avudaiappan,Chunwei Zhang 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.5

The past earthquakes revealed the importance of the design of moment-resisting reinforced concrete framed structures with ductile behavior. Due to seismic activity, failures in framed structures are widespread in beam-column joints. Hence, the joints must be designed to possess sufficient strength and stiffness. This paper investigates the effects of fibers on the ductility of hybrid fiber reinforced self-compacting concrete (HFRSCC) when subjected to seismic actions; overcoming bottlenecks at the beam-column joints has been studied by adding low modulus sisal fiber and high modulus steel fiber. For this, the optimized dose of hooked end steel fiber content (1.5%) was kept constant, and the sisal fiber content was varied at the rate of 0.1%, up to 0.3%. The seismic performance parameters, such as load-displacement behavior, ductility, energy absorption capacity, stiffness degradation, and energy dissipation capacity, were studied. The ductility factor and the cumulative energy dissipation capacity of the hybrid fiber (steel fiber, 1.5% and sisal fiber, 0.2%) added beam-column joint specimen is 100% and 121% greater than the control specimen, respectively. And also the stiffness of the hybrid fiber reinforced specimen is 100% higher than the control specimen. Thus, the test results showed that adding hybrid fibers instead of mono fibers could significantly enhance the seismic performance parameters. Therefore, the hybrid fiber reinforced concrete with 1.5% steel and 0.2% sisal fiber can be effectively used to design structures in seismic-prone areas.

Synthesis and Cytotoxic Evaluation of Novel 2-(4-(2,2,2-Trifluoroethoxy)-3-methylpyridin-2-ylthio)-1H-benzo[d]imidazole Derivatives

S. R. Ranganatha,C. V. Kavitha,K. Vinaya,D. S. Prasanna,S. Chandrappa,Sathees C. Raghavan,K. S. Rangappa 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.10

The present work deals with the anticancer effect of benzimidazole derivatives associated with the pyridine framework. By varying the functional group at N-terminal of the benzimidazole by different L-amino acids, several 2-(4-(2,2,2-trifluoroethoxy)-3-methylpyridin-2-ylthio)-1Hbenzo[d]imidazole derivatives 9(a-j) were synthesized. Their chemical structures were confirmed by 1H NMR, IR and mass spectroscopic techniques. The synthesized compounds were examined for their antiproliferative effects against human leukemia cell lines, K562 and CEM. The preliminary results showed most of the derivatives had moderate antitumor activity. Compound 9j containing cysteine residue exhibited good inhibition compared to other amino acid resides. In addition DNA fragmentation results suggest that 9j is more cytotoxic and able to induce apoptosis.

Deposition of zinc–zinc phosphate composite coatings on steel by cathodic electrochemical treatment

Kavitha, C.,Sankara Narayanan, T. S.,Ravichandran, K.,Park, I. S.,Lee, M. H. Springer Science + Business Media 2014 Journal of coatings technology and research Vol.11 No.3

The present work aims at the development of an energy-efficient and eco-friendly approach for the deposition of zinc phosphate coatings on steel. The study describes the possibility of preparing zinc-zinc phosphate composite coatings by cathodic electrochemical treatment using dilute phosphoric acid as an electrolyte and zinc as an anode. The methodology enables the preparation of coatings with different proportions of zinc and zinc phosphate by suitably varying the applied current density, pH, and treatment time. Adhesion of the coating on mild steel and adhesion of paint film on the phosphate coating were found to be good. The surface morphology of the coatings exhibited platelet-type features and small white crystals (agglomerated at some places) which represented zinc and zinc phosphate, respectively. An increase in current density (from 20 to 50 mA/cm(2)) increased the size of the zinc crystals, and coatings prepared at 40 and 50 mA/cm(2) resembled that of electrodeposited zinc. Since the proportions of zinc and zinc phosphate could be varied with applied current density, pH, and treatment time, it would be possible to use this methodology to prepare coatings that would offer different degrees of corrosion protection.

Multifaceted thermoresponsive poly(N-vinylcaprolactam) coupled with carbon dots for biomedical applications

Kavitha, T.,Kim, J.O.,Jang, S.,Kim, D.P.,Kang, I.K.,Park, S.Y. Elsevier 2016 Materials Science and Engineering C Vol.61 No.-

<P>A fluorescent thermoresponsive polymer consisting of poly(N-vinylcaprolactam) (PVCL) coupled with carbon dots (CDs) (PVCL-CDs) was synthesized by reacting a carboxyl-terminated PVCL derivative with CDs via N-hydroxysuccinimide and N-(3-(dimethylamino)propyl)-N-ethylcarbodiimide hydrochloride coupling. The temperature-dependent fluorescence properties of this material were studied for biomedical applications. Fluorescence quenching in PVCL-CDs was observed above the lower critical solution temperature (LCST) due to thermo-induced aggregation of the PVCL chains. This fluorescent thermoresponsive PVCL-CDs showed good biocompatibility and was demonstrated as a thermometer for sensing intracellular temperatures and also as a marker for bioimaging. In addition, PVCL-CDs showed a significant fluorescence turn-on response to proteins above the LCST, which allows for the utilization of this material in biosensors. Thus, PVCL-CDs, with its tuneable size, low cytotoxicity, good photostability, ease of bioconjugation, and resistance to metabolic degradation, is a novel material for biomedical applications. (C) 2015 Elsevier B.V. All rights reserved.</P>

Profitable ultrasonic assisted microwave disintegration of sludge biomass: Modelling of biomethanation and energy parameter analysis

Kavitha, S.,Rajesh Banu, J.,Kumar, Gopalakrishnan,Kaliappan, S.,Yeom, Ick Tae Elsevier 2018 Bioresource technology Vol.254 No.-

<P><B>Abstract</B></P> <P>In this study, microwave irradiation has been employed to disintegrate the sludge biomass profitably by deagglomerating the sludge using a mechanical device, ultrasonicator. The outcomes of the study revealed that a specific energy input of 3.5 kJ/kg TS was found to be optimum for deagglomeration with limited cell lysis. A higher suspended solids (SS) reduction and biomass lysis efficiency of about 22.5% and 33.2% was achieved through ultrasonic assisted microwave disintegration (UMWD) when compared to microwave disintegration – MWD (15% and 20.9%). The results of biochemical methane potential (BMP) test were used to estimate biodegradability of samples. Among the samples subjected to BMP, UMWD showed better amenability towards anaerobic digestion with higher methane production potential of 0.3 L/g COD representing enhanced liquefaction potential of disaggregated sludge biomass. Economic analysis of the proposed method of sludge biomass pretreatment showed a net profit of 2.67 USD/Ton respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Floc deagglomeration happens significantly at 3.5 kJ/kg TS of ultrasonic energy. </LI> <LI> Biomass lysis efficiency of 33.2% was achieved in phase separated disintegration. </LI> <LI> Phase separation shows better amenability towards anaerobic biodegradation. </LI> <LI> Net profit of about 2.67 USD/Ton was achieved in phase separated disintegration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>