Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
19 results
Search Results
Item Novel NiWO4-ZnO-NRGO Ternary Nanocomposites with Enhanced Photocatalytic Activity(Elsevier Ltd, 2018) Mohamed, M.; Krishna Bhat, D.A novel NiWO4-ZnO-NRGO ternary nanocomposite was efficiently synthesized via a facile, fast and easy microwave irradiation technique and its capability to photodegrade organic dye in aqueous solution was investigated. The products were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic activity was evaluated by estimating the extent of photodegradation of methylene blue (MB) under irradiation of visible light source, which showed 9 times enhancement for the ternary composites compared to that for pure NiWO4. The outcomes reveal that the novel NiWO4-ZnO-NRGO ternary nanocomposite could be a highly efficient visible light photocatalyst for the removal of environmental contaminants in wastewater. © 2018 Elsevier Ltd.Item The present study deals with the treatment of weak domestic wastewater in UASB(up flow anaerobic sludge blanket) reactor system. An experimental reactor, made of PVC tubes, 24 litre capacity was used for the experiment to evaluate the performance of the reactor. The HRT(hydraulic retention time) was maintained as 3 days. The study was carried out for a period of 40 days. The results of the experiment indicate that the anaerobic treatment of domestic wastewater in UASB reactor is a promising technique for tropical countries. © Enviromedia.(Treatment of domestic wastewater by UASB system for tropical countries) Srinikethan, G.; Shrihari, S.; Pradeepan, V.S.2004Item Petrochemical wastewater treatment using constructed wetland technique(EM International rktem@pn3.vsnl.net.in, 2016) Sudarsan, J.S.; Annadurai, R.; Subramani, S.; George, R.B.Constructed Wetlands are artificially developed ecosystem created to treat the wastewater it was normally like wetlands that occur where water conditions are intermediate between uplands and deep-water aquatic systems. Natural wetlands are capable of improving; the water quality. The ability of natural wetland systems has been recognized for more than 25 years and during this period, the use of engineered wetlands has evolved from a research concept to an accepted pollution control technology. The engineered wetland systems or Constructed Wetland Technology are treatment technologies that mimic natural wetland systems and these treatment techniques were incorporated as components of waste water treatment systems. Two general types of shallow vegetated ecosystems are being used for water quality treatment: (1) free water surface (surface flow) and (2) subsurface flow (vegetated submerged bed) systems. This paper reviews treatment of petrochemical wastewater using constructed wetland. The analysis was done on a lab scale model developed using a PVC tub with a size of 70X40X30 cm and a slight slope of (<1%) between inlet and outlet zones. This technology acts as a natural and low cost treatment facility for wastewater. In this study the plants used were Typha latifolia and Pragmites Australis. The parameters like Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Nitrogen, Phosphorus, Phenolic Compounds were studied based on APHA guidelines. The pollutant removal mechanism was also reviewed. It was found that the reduction efficiency of BOD, COD, TSS was found to be 90 to 95 % and the Phenolic compound removal efficiency was found to be 65 to 90%. Pollutant removal was highly dependent on retention time and influent concentration and by the action of internal plant communities and microorganisms, water depth. © © EM International.Item The combined effects of carbon/nitrogen ratio, suspended biomass, hydraulic retention time and dissolved oxygen on nutrient removal in a laboratory-scale anaerobic–anoxic–oxic activated sludge biofilm reactor(IWA Publishing, 2018) Manu, D.S.; Thalla, A.K.The current trend in sustainable development deals mainly with environmental management. There is a need for economically affordable, advanced treatment methods for the proper treatment and management of domestic wastewater containing excess nutrients (such as nitrogen and phosphorus) which can cause eutrophication. The reduction of the excess nutrient content of wastewater by appropriate technology is of much concern to the environmentalist. In the current study, a novel integrated anaerobic–anoxic–oxic activated sludge biofilm (A2O-AS-biofilm) reactor was designed and operated to improve the biological nutrient removal by varying reactor operating conditions such as carbon to nitrogen (C/N) ratio, suspended biomass, hydraulic retention time (HRT) and dissolved oxygen (DO). Based on various trials, it was seen that the A2O-AS-biofilm reactor achieved good removal efficiencies with regard to chemical oxygen demand (95.5%), total phosphorus (93.1%), ammonia nitrogen concentration (NH4þ-N) (98%) and total nitrogen (80%) when the reactor was maintained at C/N ratio of 4, suspended biomass of 3 to 3.5 g/L, HRT of 10 h, and DO of 1.5 to 2.5 mg/L. Scanning electron microscopy (SEM) of suspended and attached biofilm showed a dense structure of coccus and bacillus bacteria with the diameter ranging from 0.3 to 1.2 ?m. The Fourier transform infrared (FTIR) spectroscopy results indicated phosphorylated macromolecules and carbohydrates mix or bind with extracellular proteins in exopolysaccharides. © IWA Publishing 2018.Item Visible light-induced photocatalytic degradation of Reactive Blue-19 over highly efficient polyaniline-TiO2 nanocomposite: a comparative study with solar and UV photocatalysis(Springer Verlag service@springer.de, 2018) Kalikeri, S.; Kamath, N.; Gadgil, D.J.; Shetty K, V.Polyaniline-TiO2 (PANI-TiO2) nanocomposite was prepared by in situ polymerisation method. X-ray diffractogram (XRD) showed the formation of PANI-TiO2 nanocomposite with the average crystallite size of 46 nm containing anatase TiO2. The PANI-TiO2 nanocomposite consisted of short-chained fibrous structure of PANI with spherical TiO2 nanoparticles dispersed at the tips and edge of the fibres. The average hydrodynamic diameter of the nanocomposite was 99.5 nm. The band gap energy was 2.1 eV which showed its ability to absorb light in the visible range. The nanocomposite exhibited better visible light-mediated photocatalytic activity than TiO2 (Degussa P25) in terms of degradation of Reactive Blue (RB-19) dye. The photocatalysis was favoured under initial acidic pH, and complete degradation of 50 mg/L dye could be achieved at optimum catalyst loading of 1 g/L. The kinetics of degradation followed the Langmuir-Hinshelhood model. PANI-TiO2 nanocomposite showed almost similar photocatalytic activity under UV and visible light as well as in the solar light which comprises of radiation in both UV and visible light range. Chemical oxygen demand removal of 86% could also be achieved under visible light, confirming that simultaneous mineralization of the dye occurred during photocatalysis. PANI-TiO2 nanocomposites are promising photocatalysts for the treatment of industrial wastewater containing RB-19 dye. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.Item Solar light-driven photocatalysis using mixed-phase bismuth ferrite (BiFeO3/Bi25FeO40) nanoparticles for remediation of dye-contaminated water: kinetics and comparison with artificial UV and visible light-mediated photocatalysis(Springer Verlag service@springer.de, 2018) Kalikeri, S.; Shetty K, V.Mixed-phase bismuth ferrite (BFO) nanoparticles were prepared by co-precipitation method using potassium hydroxide as the precipitant. X-ray diffractogram (XRD) of the particles showed the formation of mixed-phase BFO nanoparticles containing BiFeO3/Bi25FeO40 phases with the crystallite size of 70 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the formation of quasi-spherical particles. The BFO nanoparticles were uniform sized with narrow size range and with the average hydrodynamic diameter of 76 nm. The band gap energy of 2.2 eV showed its ability to absorb light even in the visible range. Water contaminated with Acid Yellow (AY-17) and Reactive Blue (RB-19) dye was treated by photocatalysis under UV, visible, and solar light irradiation using the BFO nanoparticles. The BFO nanoparticles showed maximum photocatalytical activity under solar light as compared to UV and visible irradiations, and photocatalysis was favored under acidic pH. Complete degradation of AY-17 dyes and around 95% degradation of RB-19 could be achieved under solar light at pH 5. The kinetics of degradation followed the Langmuir–Hinshelhood kinetic model showing that the heterogeneous photocatalysis is adsorption controlled. The findings of this work prove the synthesized BFO nanoparticles as promising photocatalysts for the treatment of dye-contaminated industrial wastewater. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.Item Performance evaluation of horizontal and vertical flow constructed wetlands as tertiary treatment option for secondary effluents(Springer Verlag, 2019) Thalla, A.K.; Devatha, C.P.; Anagh, K.; Sony, E.Constructed wetlands (CWs) are simple low-cost wastewater treatment units that use natural process to improve the effluent water quality and make it possible for its reuse. In the present study, a comparison is made between horizontal subsurface flow (HSSF-CW) and vertical flow (VFCW) constructed wetland in effectively post-treating the effluents from the secondary biological treatment system. Locally available plants, viz. Pennisetum pedicellatum and Cyperus rotundus, which are abundantly available in the Western Ghats, were used in the wetland. A pilot-scale study was undertaken in National Institute of Technology, Karnataka Campus. The experiments were conducted at two hydraulic retention times, i.e., 12 h and 24 h. The experimental study was carried out in February 2018 to May 2018. Concentration-based average removal efficiencies for HSSF-CW and VFCW were BOD, 77% and 83%; COD, 60% and 65%; NH4 +–N, 67% and 84.47%; NO3–N, 69% and 66.75%; and PO4–P, 85% and 90%, respectively. VFCW showed a better overall removal efficiency than HSSF-CW by 7.14%. Thus, constructed wetland can be considered as a sustainable alternative to the tertiary conventional treatment of domestic wastewater, thus making it possible for reuse. © 2019, The Author(s).Item Removal of ametryn and organic matter from wastewater using sequential anaerobic-aerobic batch reactor: A performance evaluation study(Academic Press, 2019) Mahesh, G.B.; Manu, B.The present study was aimed to investigate biodegradation of 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryn) in a laboratory-scale anaerobic sequential batch reactor (ASBR) and followed by aerobic post-treatment. Co-treatment of ametryn with starch is carried out at ambient environmental conditions. The treatment process lasted up to 150 days of operation at a constant hydraulic retention time (HRT) of 24 h and an organic loading rate (OLR) of 0.21–0.215 kg-COD/m3/d. Ametryn concentration of 4 and 6 mg/L was removed completely within 48–50 days of operation with chemical oxygen demand (COD) removal efficiencies >85% at optimum reactor conditions. Ametryn acted as a nutrient/carbon source rather causing toxicity and contributed to methane gas production and sludge granulation in the anaerobic reactor. Biotransformation products of ametryn to cyanuric acid, biuret, and their further conversion to ammonia nitrogen and CO2 are monitored during the study. Adsorption of ametryn on to reactor sludge was negligible, sludge granulation, presence of ANAMMOX bacteria, and low MLVSS/MLSS ratio between 0.68 and 0.72. The study revealed that ametryn removal occurred mainly due to biodegradation and co-metabolism processes. Aerobic post-treatment of anaerobic effluent was able to remove COD up to 95%. The results of this study exhibit that anaerobic-aerobic treatment is feasible due to easy operation, economic, and highly efficient. © 2019 Elsevier LtdItem Use of redox mediators for the enhanced degradation of selected nitrophenols(Springer Verlag, 2019) Yaseen, M.; Manu, B.; Kudri, N.; Govardhanaswamy, H.S.In the present study, sequential anaerobic–aerobic treatment was used for the enhanced degradation of selected nitrophenols. Five identical reactors were used to assess the degradation of 2-nitrophenol and 2,4-dinitrophenol. Reactor 1 was used as control, and another four reactors were operated in anaerobic phase followed by sequential aerobic treatment. The performance of reactors was studied for nitrophenol concentrations of 5, 10, 20 and 40 mg/l and in next phase effect of redox mediators [lawsone and anthraquinone sulphonic acid (AQSA)], along with kinetics of degradation studied for 40 mg/l of nitrophenols. More than 98% degradation of nitrophenols was achieved at lower concentrations but for 40 mg/l removal percentage was reduced, and also COD inhibition was observed. However, with the addition of redox mediators, both nitrophenols and COD removal percentage were greater than 95% and 85%, respectively. Kinetics of degradation revealed that the rate of degradation was found to increase with the increase in concentration of redox mediators from 10 to 20 mg/l, and it was found that degradation was faster with the use of AQSA in comparison with lawsone solution. It indicates that use of redox mediators is favourable for the enhanced degradation of nitrophenols. Sequential anaerobic–aerobic treatment is possible potential treatment method for treating nitrophenolic wastewaters. © 2019, The Author(s).Item Floating bed reactor for visible light induced photocatalytic degradation of Acid Yellow 17 using polyaniline-TiO2 nanocomposites immobilized on polystyrene cubes(Springer, 2020) Nair, V.R.; Shetty K, V.In the present study, PANI-TiO2 nanocomposites have been used in suspended and immobilized form for photocatalytic degradation of Acid Yellow 17 (AY-17) dye under visible light. PANI-TiO2 nanocomposites were immobilized in polystyrene cubes to form PANI-TiO2 @ polystyrene cubes. The nanocomposites were found to be visible light active both in suspended and immobilized form. PANI-TiO2 nanocomposite with 13% TiO2 loading was found to be the optimum in terms of maximum degradation of AY-17. The efficiency of floating bed photoreactor (FBR) operated in liquid recycle mode using PANI-TiO2 @ polystyrene cubes was studied. In this reactor, around 89% degradation of 1 L of AY-17 with an initial concentration of 10 mg/L could be achieved with 2.83 g/L per pass of immobilized catalyst. The FBR operated with PANI-TiO2 @ polystyrene cubes has exhibited good performance as a photocatalytic reactor and may be recommended over other conventional photo reactors for treatment of wastewater contaminated with synthetic dyes. The kinetics of degradation of AY-17 by photocatalysis under visible light with suspended PANI-TiO2 and PANI-TiO2 @ polystyrene cubes followed first-order kinetics. The values of apparent kinetic parameter for degradation by immobilized photocatalysts are lower than the corresponding kinetic parameter for suspended photocatalysts. It confirms the existence of diffusional limitations in photocatalysis by PANI-TiO2 @polystyrene cubes. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.