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Item STUDIES ON PRODUCTION AND APPLICATIONS OF ALKALINE PROTEASE FROM BACILLUS PSEUDOFIRMUS(2010) Sen, ShampaMicrobial alkaline proteases are one of the most important hydrolytic enzymes and hence are being studied extensively since last two decades. These enzymes constitute 60% to 65% of the total enzymes sales in the world. These enzymes have versatile applications in many industries viz., tannery, dairy, food, pharmaceutical, silk, detergent, waste management and effluent treatment. Microbial alkaline proteases, especially from Bacillus sp. are most widely exploited industrially. In general, the majority of the commercially available enzymes are not stable in the presence of oxidizing agents, organic solvents and wide range of pH as well as temperature. An efficient alkaline protease producer was isolated from a tannery waste soil, which grew in a wide range of pH. A new screening media was designed containing gelatin as a sole source of carbon and nitrogen. The culture broth (supernatant) was found to hydrolyze natural proteins viz., clotted blood, egg white and poultry feather. Very efficient dehairing was achieved using the culture broth (supernatant). The isolate was identified to be Bacillus pseudofirmus and designated as B. pseudofirmus SVB1 on the basis of 98% similarity in 16s rRNA sequence. Physical parameters viz., initial pH of the medium, temperature and rpm of the shaking incubator were optimized using central composite experimental design to enhance the production of alkaline protease and cell growth simultaneously. The individual optimum levels of parameters were found to be 9.2, 27DC and 195 for initial pH of the medium, temperature and rpm of the shaking incubator, respectively for the 210, respectively for cell growth. From multi-response analysis, the optimal levels were found to be 9.6, 28DC and 191 rpm for initial pH of the medium, temperature and rpm of the shaking incubator, respectively for both production and cell growth. The values of cell growth (A600), alkaline protease activity and specific activity obtained were 0.44, 40.03 U/ml, 6.37 U/mg, respectively, under these optimal conditions. Before optimization the values were 0.30, 30.56 U/ml, 4.7 U/mg, for cell growth (A600), alkaline protease activity and specific activity, respectively. The production of alkaline protease and cell growth were enhanced by 36% and 44%, respectively under optimal levels of the physical parameters. The results obtained from optimization of individual responses and multi-response were compared. Medium was developed to maximize the production of alkaline protease from B. pseudofirmus SVB1 in three steps. In the first step, various carbon/nitrogen source and salts were selected using one variable at a time (OVAT) method. Casein was found to be the most efficient source for both carbon and nitrogen for alkaline protease production along with MgSO4, CaCl2, NH4NO3, FeCl3, K2HPO4, KH2PO4 and NaCl. In the second step, Plakett-Burman experimental design was applied to screen the significantly influencing medium components, and casein, MgSO4, NH4NO3 and CaCl2 were selected for optimization of their levels. These medium components were optimized using central composite experimental design in the third step to improve the production. The optimal levels of casein, MgSO4, CaCl2 and NH4NO3 were found to be 7.636 g/l, 0.811 g/l, 0.086 g/l and 0.576 g/l, respectively. An overall 4.9 fold increase in alkaline protease production (specific activity) was achieved in th..........Item Green Synthetic Methodologies Using Innocuous Reagents and Removel of Nitrobenzene using Cloud Point Extraction(2010) Nath, JayashreeThe contents of this thesis have been divided into two chapters based on the results of experimental works performed during the complete course of the research period. the first chapter of the thesis again has been divided into two parts. ..............Item Biodegradation of Phenolic and Petroleum Wastewater by Isolated Bacillus cereus(2011) Banerjee, AditiThe thesis mainly focuses on the isolation of phenol-degrading bacteria from oilcontaminated sites and their application in the biodegradation of phenolic and petroleum wastewaters. Firstly, two potential phenol-degrading bacterial strains were isolated from two different site specific petroleum wastewaters and identified as Bacillus cereus MTCC 9817 strain AKG1 and Bacillus cereus MTCC 9818 strain AKG2, based on the 16S rDNA gene sequencing. In addition to the various morphological and biochemical characterizations, the optimum growth conditions and growth kinetics for both AKG1 and AKG2 were investigated. Next, biodegradation of phenol at various initial concentrations by isolated B. cereus strains were studied at their optimum physiological condition. The degradation kinetics revealed that the Haldane model fitted the experimental data fairly well. The phenol degradation mechanism in the isolated strains was also elucidated. Treatment of real petroleum wastewater samples, studied in batch mode by free cultures, demonstrated that coculture of the free cells (AKG1 and AKG2) was most efficient in removing COD, TOC and ammonium nitrogen. Probable identification of bio-degradation products was performed by liquid chromatography and mass spectroscopy. Also, an attempt has been made to probe the structural changes of bacterial cell membrane as a result of the bacterial adaptation to the toxic environment of the petroleum wastewater. The investigation with Ca-alginate immobilized AKG1 and AKG2 demonstrated enhanced tolerance of the immobilized cells to higher phenol concentrations (~ 2000 mg L-1). The storage stability of the immobilized strains and their potential application in repeated batch biodegradation has also been evaluated. Degradation kinetics indicated that phenol degradation by immobilized strains could well be fitted by Haldane model. Moreover, biodegradation of petroleum wastewater samples by alginate immobilized strains have been investigated and the reduction in COD, TOC and ammonium nitrogen level evaluated. The immobilized cells were found to be less effective than the free cell systems in treating petroleum wastewater. Finally, the fabrication and initial optimization of lab scale bioreactors for degrading phenolic and petroleum wastewater Ca-alginate immobilized Bacillus cereus (AKG1 and AKG2) were investigated. The performance of immobilized strains in phenol degradation in a packed bed reactor was studied and the combined effect of external mass transfer with biochemical reaction on the mass transfer correlation was determined in terms of Colburn factor (JD) and Reynolds number (NRe). Continuous biodegradation of the petroleum wastewater was carried out in re-circulated packed bed reactors by the isolated strains immobilized in either Ca-alginate beads or polyurethane foam (PUF) cubes. The biodegradation performances of both the immobilized systems demonstrated the excellent efficacy of the immobilized AKG1 and AKG2 strains in treating petroleum wastewater in continuous mode of operation. Continuous biodegradation of petroleum refinery wastewater in re-circulated fluidized bed reactors also demonstrated that the microbial treatment reduced the initial COD level and concentration of phenolic compounds efficiently...Item Traffic Flow Characteristics and Impacts on Air Quality at Urban Roundabout Junction(2011) Suresh, Pandian E.Rapid urbanization and the unprecedented growth in vehicles have resulted in profound deterioration of air quality in urban centers. Traffic junctions of urban centers often attract large number of vehicles creating congested conditions which, as a result, generate higher carbon monoxide (CO) emissions. Since traffic flow characteristics generally observed at junctions complicate dispersion phenomena, understandings on pollutant dispersions in the close vicinity of traffic junctions are important for accurate air quality assessment. Traffic junctions in particular of type conventional roundabouts, where vehicles spiral in and out change lanes and vary speeds in circular pattern, tend to impose behavioural changes on drivers to utilize the free space on road while maneuvering. This generates a zone in which emissions are recirculated within road-width leading to the canyon-type effects between the continuous moving vehicles. Several dispersion models exist to evaluate air quality near roadways and traffic junctions. However, complex pollutant dispersion at a conventional non-signalized roundabout cannot be described accurately by either intersection or open-terrain line source models alone. In order to simulate such a complex dispersion pattern at a nonsignalized roundabout, it is proposed that a line source model is combined with streetcanyon effects. This is demonstrated by estimating 1-min average CO concentration for a period of 30 min by coupling an open-terrain line source model, GFLSM with a streetcanyon (SC) model, STREET to capture the combined (SC-GFLSM) effects to describe the dispersion pattern. This research involves the development of detailed methodologies to quantify traffic flow characteristics and emissions pertinent to local conditions as inputs to the SC-GFLSM model. A time-width occupancy model was developed to simulate traffic flow characteristics and semi-empirical model was developed to simulate emission pattern. The results show that the GFLSM predicted measured concentrations almost three times higher, while the results of the SC-GFLSM matched well with the measurements and the prediction errors reduced by about 50 %. The research, further, demonstrated this with traffic characteristics and emissions calculated by field and semi-empirical methods. The SC-GFLSM model was also validated for another 30 min data set for which the results were equally promising.....Item Studies on Biodegradation of Substituted Phenols by Arthrobacter Chlorophenolicus A6(2011) Sahoo, Naresh KumarThe presence of substituted phenols in water, soil and wastewater is of severe public health concern due to their detrimental effect on human and many other living organisms. Their removal from contaminated water and wastewater is necessary for protection of environment and human well being. Substituted phenols especially chloro, bromo and nitro phenols are one of the most widely used chemical compounds in many industries throughout the world. Although several techniques such as photo-decomposition, physical adsorption, solvent extraction, chemical oxidation and electrochemical methods have been tested for the removal of phenol and phenolic compounds from wastewaters, high cost, low efficiency and generation of toxic by-products are some of the limiting factors of these methods. The ecofriendly biodegradation process has gained maximum attention due to its many advantages over the traditional physico-chemical methods. The main objective of the present investigation was to develop a complete treatment system for substituted phenols bearing wastewater in aerobic process using an actinomycetes strain of Arthrobacter chlorophenolicus A6. The substituted phenols investigated in this study were 4-chlorophenol (4-CP), 4- bromophenol (4-BP) and 4-nitrophenol (4-NP) both as single substrate and mixed substrate system. As a first step, optimization of culture media components were carried out employing statistical design of experiments including 2-level factorial design, central composite design and response surface methodology (RSM). The media optimization results revealed 100% of 4-chlorophenol biodegradation efficiency with a maximum specific growth rate of 0.093 h-1 at an optimum composition of (g l-1) K2HPO4 initial concentration as high as 375 mgl-1 within a time period of 40 h, which is so far the best 4-CP degradation concentration in literature in batch shake flask. 2.62, KH2PO4 0.4, NH4NO3 0.58, MgSO4 0.171, CaCl2 0.038 and FeCl3 0.002 in the medium. Similarly the RSM optimized result of physical parameter revealed that at the optimized settings of 7.5 pH, 207 rpm, 29.6 DC and 39.5 h inoculum age, 100% biodegradation of 4-CP even at a high initial concentration of 300 mg l-1 could be achieved within a short span of 18.5 h of culture. The enhancement in the 4-CP biodegradation efficiency was found to be 23% higher than that obtained at the unoptimized settings of the culture conditions. In addition, at the optimized culture conditions the actinomycetes could degrade 4-CP at an Biomass growth data were also obtained, which sugested that even though 4-NP was degraded prior to 4-CP and 4-BP, it had a stronger negative impact on the cells than the other two. The maximum yield value obtained in the present study (0.2152 gg-1 at 125, 125, and 50 mgl-1 of 4-CP, 4-BP and 4-NP respectively) also less when compared with several literatures reported values which ranges from 0.44-0.88 gg-1 on biodegradation of phenolic compounds using different microbial culture. inhibition constant (Ki) of 5FU. I also persuaded in silico molecular dynamics stimulation to confer interactions of uracil and its selective inhibitor 5FU with UPRT enzyme. The computational results revealed key residues of UPRT involved in ligand binding interactions. In this part of my thesis, I have developed a biodegradable chitosan based nanocarrier (NC) for protein encapsulati.Item Interication of Proteins and Ions at different Tailor-made Solid-Liquid Interface(2011) Saha, BedabrataAbstract not available.Item Optimal Ecological Management Practices for Controlling Sediment and Water Yield from a Hilly Urban System within Sustainable Limit(2012) Sarma, BanasriUrbanization is increasing at a rapid rate and in many places expanding into the hilly areas, thereby inducing significant alteration in the hydrological response of watershed. In the developing world, the process of urbanization is more often unplanned and disorganized, which results in higher yield of sediment and surface runoff, which manifest itself in the form of hazards like flash flood and landslide. Washing off of pollutants from the urbanized impermeable upper catchment is also causing downstream water quality declination. Therefore, urban developments in hilly watersheds require application of efficient management practices that can handle adverse consequences of urban developments in an ecologically sound and sustainable manner. Such ecofriendly sustainable management practices can be termed as Ecological Management Practices (EMPs). However, the cost, efficiencies and applicability of EMPs vary widely from place to place depending upon the site condition. Therefore, it is necessary to determine the optimal combination of EMPs that satisfies all requirements at minimum cost. In this study, allocation of EMPs for managing sediment and water yield from hilly urban watershed has been done through an optimization model. Due emphasis was given towards prioritization of EMP application projects based on severity of watershed degradation and their impacts on surroundings. A GIS based River Water Quality Information System (RWQIS) was developed with a primary objective of identifying most degraded watersheds by considering river water quality as an index of catchment degradation. To demonstrate applicability of the RWQIS, it was applied to Northeastern Region of India and two rivers of Guwahati City- Bharalu and Basistha were identified as most urban impacted rivers of the region. A systematic procedure for studying pattern of urban expansion by using geoinformatics was developed and applied to the Guwahati City along with a socioeconomic survey to help development planning associating hydrological aspects. Two adjacent watersheds were developed as disturbed and undisturbed watershed for studying hydrological response of residential development in terms of sediment and water yield and also for conducting experimentation on performance of some competitive EMPs. The study revealed that sediment yield and water yield per unit area increases by 2 - 21% and 3 - 54% respectively in the disturbed watershed as compared to the undisturbed watershed. Experimentation on erosion control efficiency of EMPs proved Grass (Paspalum conjugatum) and Golden glory (Tradescantia zebrina) to be highly efficient; Grass has efficiency of 75-100% and Golden glory has efficiency of 36-97% as compared to bare land. Analysis of chemical composition of rainwater and runoff samples showed significant ionic contribution from soil to the runoff water. Leaching study of soil revealed that leaching behavior of soil differs from site to site. Based on this study, a conceptual model was developed for determining limiting value of sediment yield from a watershed from the water quality perspective. Three optimization models, namely, OPTEMP-LS (OPTimal EMP model with Linear programming for Single ownership), OPTEMP-LM (OPTimal EMP model with Linear programming for Multiple ownership) and OPTEMP-LDM (OPTimal EMP model.Item Performance evaluation of continuous and fed batch sequential moving bed reactors for removals of phenol thiocyanate and ammonia-nitrogen from wastewater(2012) Sahariah, Biju Prava(SMA) was achieved up to feed SCN- 200 mg/L in R1/B1. Increased HRT enhanced the pollutant removal efficiencies. Phenol and COD removal in R1 was significantly inhibited at feed phenol, SCN- and NH4 +-N concentration 1500, 200, and 500 mg/L or above whereas inhibition in B1 was observed at phenol, thiocyanate and pyridine concentrations of 2000, 400 and 50 mg/L, respectively. Increased fill time negatively affected phenol/COD removal; however, instant fill was strongly unfavorable and gradual short fill facilitated performance of B1. Increased cycle time enhanced pollutant removal efficiency in B1 by increasing reactor HRT. In both R1 and B1 Lactobacillus sp. and Streptococcus sp. were common. Influent to R2/B2 constituted by effluent from R1/B1 and recycle from R3/B3 (recycle ratio 1) with additional nitrate. Simultaneous phenol, thiocyanate, COD and nitrate removals were achieved. NH4 +-N concentration increased along with sulfate due to thiocyanate degradation. SCN- concentration of 54-400 mg/L in influent caused no significant inhibitory effect on phenol, thiocyanate and COD removal in R2/B2; however higher phenol concentration (above 468 mg/L in R2 and 511 mg/L in B2) showed negative effect on SCN- removal. Contribution of R2 and B2 in SCN- removal was significantly high compared to R3 and B3. In FMBR system B1 highly contributed in total phenol and COD removal, whereas in CMBR system both R2 and R3 were significantly responsible for phenol and COD removals. It was observed that nitrate- nitrogen was essential for SCN- removal. COD:N removal ratio was 3-7 in R2 and 2.2-6 in B2. R2 showed presence of Streptococcus sp., Neisseria sp., Corynebacterium sp. and Citrobacter sp.. Similar to thiocyanate removal, B2 showed higher pyridine removal compared to B1 and B3. Pyridine caused no inhibitory affect in B2 in terms of phenol/COD removal though at high concentration (127 mg/L) it affected SCN- removal. Increased cycle time enhanced pollutant removal whereas change in fill time showed insignificant affect on performance of B2 and the optimum fill time was 3-5 hour. Pseudomonas sp., Enterobacter sp., E. coli and Citrobacter sp. were observed in B2..Item Studies on Microbial Reduction of Perchlorate in Batch and Continious Systems(2013) Ghosh, AtreyiPerchlorate contamination of the ground water, soil and surface water is a public health concern of recent times due to their detrimental effect of human health and other living entities. Therefore, its removal from contaminated systems is necessary for the human well being and environment. Perchlorate salts (especially ammonium and sodium) are extensively used mostly in military ammunitions and fireworks industries all over the world. Several removal techniques such as ion exchange, adsorption and precipitation, chemical and electro-chemical processes have been tested for perchlorate from water systems. Those techniques majorly suffer from one or more disadvantages like, high maintenance cost, regeneration of brines and inefficient removal of perchlorate etc. In this scenario, the ecofriendly bioreduction using microbes in pure or mixed cultures shows promising future in the field of perchlorate removal from water and wastewater. The main focus of the present investigation was to develop a complete anaerobic treatment system for perchlorate bearing wastewater in anaerobic process using a mixed microbial consortium. The mixed microbial consortium was collected from an activated sludge reactor and investigated for its potential in perchlorate degradation from synthetic wastewater in batch shake flasks and as well as continuous systems. The capacity of the mixed microbial consortium to reduce perchlorate using phenol and other five different carbon sources and phenol was tested in batch system. Compared to other tested carbon-sources used in this study, succinate has proven to be better for perchlorate degradation by the mixed consortium predominantly Burkholderia sp. on the other hand the mixed microbial consortium predominantly Pseudoxanthomonas sp. was found to utilize phenol as sole C-source for perchlorate bioreduction which is reported for the first time. The mixed microbial culture grown in batch mode with perchlorate along with succinate and phenol separately was isolated to identify the predominant strains. The 16S rDNA analysis of the predominant strain showed to be Burkholderia. sp. using succiante as sole C-source in the mixed culture. For the first time Burkholderia. sp., predominantly present in this mixed culture, has been reported to be involved in perchlorate degradation. Newly isolated bacterial species Pseudoxanthomonas sp. isolated from a sewage sludge consortium was found to reduce perchlorate while taking phenol as electron acceptor. The optimum conditions for perchlorate reduction by the enriched mixed culture predominantly Burkholderia sp. was found to be 30oC and pH 7.0. Plackett and Taguchi design was employed for screening 5 parameters for perchlorate degradation from two isolated bacterial strains Burkholderia sp. and Pseudoxanthomonas sp., utilizing succinate and phenol as C-source. Four physical parameters: temperature, pH, inoculums age and inoculums volume were selected along with the ration of carbon source and perchlorate concentration. Coefficients and sum of squares ratio in percentage (%) of these variables were calculated by subjecting the experimental data to statistical analysis. Temperature, inoculum age and carbon to perchlorate ration showed significant importance in perchlorate degradation by mixed consortium predominantly with Burkholderia sp. using succinate as C .Item Climate Change in the Brahmaputra Valley and Impact on Rice and Tea Productivity(2013) Deka, Rajib LochanGiven the vulnerability of agricultural sector to variations in weather conditions, it will be one of the sectors most affected by climate change. This study assesses the state of climate change and variability in the Brahmaputra valley of India and consequent implications on productivity of two important crops rice and tea grown extensively in the valley. The trends and fluctuations of the major climatic variables were assessed using statistical techniques. A quantitative assessment of the impact of observed as well as projected climate on rice and tea productivity was carried out in the study area through statistical and process-based simulation models. Historical rainfall data from 1901 temperature data from 1951 and sunshine duration data from 1971 were analyzed for assessing long-term trends. A suite of climate change indices derived from daily rainfall (1955 and temperature (1971 data, with a primary focus on extreme events, were computed and analyzed to understand the trends. The impact of climate change and its variability on yield patterns of rice and tea were based on 26 years of district level rice yield data (1985 and 20 years of estate level tea yield data (1991 The CERES-Rice crop simulation model was used to predict rice yield under future climate scenarios. The likely impact of future climate changes on tea yield was based on the statistical models developed for monthly yields and climate data of 1991 to 2010. Annual and monsoon rainfall in the study area exhibited a weak diminishing tendency during 1901 due to significant decrease in rainfall in the eastern part of the valley. Significant declining trend of monsoon rainfall during the recent 30-year period was due to significant decrease of July and September rainfall and this trend was consistent at different spatial scales. The intensity of monsoon rainfall was found to diminish over the entire valley due to decrease in the extreme fractions of rainfall, marked by extremely wet, very wet and moderately wet days during the recent three decades (1981 Decrease of rainfall fraction due to moderately wet days was particularly significant in the eastern and western parts of the valley. Rainfall during pre-monsoon and post monsoon season showed increasing tendency during the most recent 30-year period due rise in extreme rainfall indices over the valley. Increase of rainfall during pre-monsoon was primarily contributed by significant increase of April rainfall in the western part of the valley.Item Ecological study of Brahmaputra River Floodplain in Selected Areas of Majuli and kamrup and Potential Bioresource Utilization Perspectives(2014) Gogoi, NayanmoniA primary objective of ecological monitoring programs is to detect changes in ecosystem functions and processes. Healthy ecosystem functions are the key components to balanced ecosystem services.Item Studies on Superoxide Dismutase: An antioxidative protein from Cicer arietinum seedlings(2014) Singh, SushantSuperoxide dismutase is an important enzyme of the antioxidative defense system. It forms the first line of defense against reactive oxygen species and environment induced oxidative stress. Superoxide dismutase works in coordination with other antioxidative enzymes such as catalase, ascorbate peroxidase and glutathione peroxidase. These enzymes help in maintaining the ionic homeostasis, deplete the level of reactive oxygen species and subsequently limit the oxidative stress condition. Superoxide dismutase enzymes are classified based on their metal cofactor associated with the activity. Because of its high reactive oxygen species scavenging properties, it has numerous therapeutic applications. Recent advancement in the field of proteome research coupled with detailed reaction mechanism, in depth analysis of the crystal structure and in silico analysis suggests that superoxide dismutase is indispensible tool for numerous biological applications. However, search of a novel superoxide dismutase with unique properties is always of significant importance.Item Studies on Sulfate Reduction to Elemental Sulfur Under Anaerobic/Microaerobic Conditions(2014) Brahmacharimayum, BharatiSulfate rich water with low organic content is being released in increasing quantity due to rising industrial activities.Item Direct Electrochemical Reduction of Gaseous Carbon Dioxide to Value Added Products: Investigations on Electrocatalysts(2015) Singh, SuryaThis thesis is aimed to find a solution for one of the environmental problems viz. increasing CO2 concentration in the atmosphere. The thesis focuses over this subject for the mitigation of CO2 through its utilization. Direct electrochemical reduction of gaseous CO2 (dERC) has been found to be a suitable technology which not only helps in the utilization of the CO2, but at the same time produce such reaction products which have the high calorific value. Thus, these reaction products can be used as fuels, which will also help to combat the problem of decreasing fossil fuel reserves. With this aim, the CO2 is electrocatalytically reduced and converted into a variety of products. For screening the suitable electrocatalysts form the group of many, a catalytic activity protocol has also been developed to make the dERC process quick and easy. For the conversion of CO2, different types of electrocatalysts; such as metals, metal oxides, metal complexes, and bimetal, have been developed and successfully used for the electrochemical CO2 reduction and formation of value added products. Keywords: Bimetal, Catalytic activity protocol; Electrocatalysts; Direct electrochemical reduction of CO2; Metal oxides; Salen metal complexes.Item CO2 Sequestration using Microalga Scenedesmus Obliquus SA1 Isolated from Bio-diversity Hotspot Region of Assam(2016) Basu, SamarpitaFlue gases emitted from coal-fired thermoelectric plants is responsible for up to 7% (v/v) of global CO2 emissions, about 10-15% (v/v) of the flue gases emitted from the power plants being in the form of CO2. Increased CO2 concentration in the atmosphere is responsible for global warming and climate change. The thesis focuses on the isolation and characterization of high CO2 and temperature tolerant microalga capable of sequestering CO2 from flue gas and subsequent cultivation of the microalga in bench scale open system and lab scale photobioreactor for enhanced CO2 sequestration. Microalga strain SA1 was isolated from a freshwater body of Assam and identified as Scenedesmus obliquus (KC733762). At 13.8 ± 1.5% inlet CO2 concentration and 25 °C, maximum biomass of 4.975 ± 0.003 g L−1 and maximum CO2 fixation rate of 252.883 ± 0.361 mg L−1 d−1 were obtained in the lab scale closed system studies. Also, at elevated temperature (40 °C) and 13.8 ± 1.5% CO2 supply maximum biomass value of 0.883 ± 0.001 g L−1 and maximum specific growth rate of 0.54 ± 0.020 d−1 were obtained. . The carbohydrate, protein, lipid, and chlorophyll content of the CO2 treated SA1 obtained in the lab scale closed system studies were 30.87 ± 0.64%, 9.48 ± 1.65%, 33.04 ± 0.46 and 6.03 ± 0.19% respectively. The inlet CO2 concentration of 13.8 ± 1.5% was reduced to 0.5% during logarithmic growth phase of SA1. Since the power plant flue gas contains high concentration of CO2 (around 12-15%) and is released from the power plant at high temperature (around 40-50 ºC after the desulfurization process), tolerance of high CO2 concentration and high temperature of 40 ºC temperature by S. obliquus SA1 makes it a potential strain for CO2 sequestration from flue gases. SA1 strain was subsequently cultivated in bench scale open system at varying CO2 levels ranging from 0.03-35% (v∕v) and subsequently the carbonic anhydrase activity (CA) and the biochemical properties were monitored. Maximum biomass concentration (1.39 ± 0.023 g L−1), CO2 fixation rate (97.65 ± 1.03 mg L−1 d−1) and total Carbonic anhydrase (CA) activity (166.86 ± 3.30 E.U. /mg chla) were obtained at 35% CO2 at a culture depth of 0.17 m. The culture depth was varied at 15% CO2 concentration from 0.0425 m to 0.17 m. Overall biomass productivity (54.33 ± 0.19 mg L−1 d−1), CO2 fixation rate (102.13 ± 0.36 mg L−1 d−1) and maximum biomass productivity (156.8 ± 4.37 mg L−1 d−1) were the highest at a culture depth of 0.085m. As evident from literature reports, CA activity is strongly induced when algae are grown in a low-CO2 environment. This fact was evident from our experimental finding, as CA activity of control culture (grown at ambient CO2 concentration) > CA activity of 15% CO2 treated culture > CA activity of 35% CO2 treated culture for most of the experimental period. CA inhibitors: acetazolamide and ethoxyzolamide inhibited the external and internal enzyme activity respectively in SA1, thereby confirming the presence of periplasmic (external) and intracellular CA in the SA1 strain. High CO2 levels were favorable for the accumulation of lipids and chlorophyll in the SA1 strain the values of which were 41.17 ± 0.77% and 8.47 ± 0.15% respectively. The increased lipid content could make the SA1 strain useful in biodiesel production. Also, chlorophyll is a useful commercial pigment and is regarded as an economically valuable co-product of the CO2 sequestration process. Finally, the operational parameters were varied to maximize the CO2 utilization efficiency by the SA1 strain. In these optimization studies, SA1 strain was cultivated in a lab scale cylindrical glass photobioreactor (open system) under 15% CO2 concentration at varied operational conditions (light intensity, CO2 sparging duration and CO2 flow rates). At light intensity of 4351 lux, CO2 sparging duration of 12 h per day and flow rate of 0.43 liter per hour, maximum biomass concentration of 3.32 ± 0.022 g L−1, maximum specific growth rate of 1.24 ± 0.028 d−1, maximum CO2 fixation rate of 1035.25 ± 52.98 mgL−1d−1 and maximum CO2 utilization efficiency of 10.23% were obtained which were higher than most of the relevant literature reports. These parameters were thus inferred to be the optimum condition for maximum CO2 utilization by the microalga in lab scale photobioreactor. SA1 has high biomass productivity, fast growth rates, an attractive biochemical profile, high CO2 fixation rates and utilization efficiency when cultivated in presence of 15% CO2 (typical flue gas concentration). It can thus prove to be a potential candidate for...Item Biological sulfate reduction for batch and continuous removal of heavy metals from wastewater(2017) Kiran, Mothe GopiHeavy metals are extensively used for several applications, and as a consequence of which these metals are discharged into the environment from different sources. Owing to their non biodegradable and non persistent nature, metals can merely be transformed to less toxic and insoluble forms. Besides heavy metals, sulfate is found abundant in wastewater streams which pose many environmental issues. Therefore, elimination of metals and sulfate from wastewater prior their discharge into the environment is mandatory. This study was focused on the application of sulfidogenic bioreactor systems for heavy metal removal from metallic wastewater. Initial studies were carried out to screen suitable anaerobic biomass for the removal of different heavy metals and to investigate the mechanism of metal removal from both single and multi-component systems by SRB. The SRB biomass obtained from the experiments was characterized using FTIR, TEM-EDS and FESEM-EDX and the heavy metal removal mechanism was attributed to the sulfate reducing capability of the biomass, which resulted in precipitation of the metals as their corresponding sulfide salts. FTIR spectroscopy analysis of the biomass confirmed the presence of functional groups in the SRB that were similar to that of an earlier reported SRB, Desulfovibrio. species. For a successful application of this method, the choice of a suitable reactor system is essential. Therefore, continuous metal removal from synthetic wastewater by immobilized SRB was evaluated using two lab-scale sulfidogenic bioreactor systems: anaerobic rotating biological contactor (An-RBC) reactor and a downflow column reactor (DFCR) packed with immobilized SRB beads. Best heavy metal removal results were obtained at 48 h HRT than at 24 h HRT in case of both the reactor systems. However, the removal values were reduced at a high inlet concentration of the heavy metals, which matched well with low COD and sulfate removal efficiencies, but the metal removal results were better using the An-RBC reactor than those results obtained using the DFCR. V3-V4 metagenomics sequencing and analysis revealed that SRB immobilized in the An-RBC reactor is predominant with Desulfovibrio. sp. Combined effect of different heavy metals on the removal of metals, sulfate and COD by SRB using both the reactor systems was evaluated under continuous operating condition by employing the statistically valid fractional factorial design of experiments. Continuous metal removal from a mixture of the heavy metals showed that Cu(II) removal was maximum (> 98%), followed by Zn (II) (96%) and other heavy metals at their respective low inlet concentrations, and metal removal order in the mixture study using both the reactor systems was Cu > Zn > Cd > Pb > Fe > Ni. These results strongly indicate that the passive biofilm based bioreactor (An-RBC reactor) could be preferred over DFCR for large-scale treatment of sulfate and metal rich wastewaterItem Biosorption of Pb(II) by bacterial strain bacillus badius AK isolated from rotary drum compost of water hyacinth(2017) Vishan, IshaComposting of biological waste is mainly governed by the diversity of microorganisms working intermittently or in succession in order to carry out the biochemical reactions for their metabolism. The rotary drum composting is relatively a faster method as compared to the conventional pile (windrow) composting method. The water hyacinth (Eichhornia crassipes) being a free-floating aquatic weed is creating nuisance in waterbodies, composting is found to be one of the most effective method of management and utilization of this weed. From the previous studies it was found that the total content of metal has increased to a significant amount in final compost of water hyacinth. Therefore, current study was performed to detect the microbial succession in the rotary drum composting of water hyacinth along with the stability and maturity analysis in form of different trials. Major microbial communities in the best trial (6:3:1) of water hyacinth compost were observed Bacteria. Therefore, in this thesis work rotary drum compost of water hyacinth was used as a source for isolation of bacteria. Twelve bacterial isolates were isolated and identified, which majorly belonged to the Bacillus and Entrobacter genera. The biosorption study of heavy metals such as lead (Pb(II)) and cadmium (Cd(II)) were performed with isolated bacterial strain Bacillus badius AK. Live (non-pretreated) and dried (pretreated) bacterial cells were utilized for biosorption of Pb(II) and Cd(II). Batch biosorption study of live (non-pretreated) biomass of Bacillus badius AK demonstrated maximum biosorption of Pb(II) at biomass concentration of 1.7×1016 CFU/mL. The specific growth rate and maximum specific growth rate of bacterial cells under the influence of Pb(II) were determined as 0.05/h and 2.54/h. respectively. The rate of biosorption in batch study with dried (pretreated) biomass of Bacillus badius AK was observed to be high in the first 30 min. The maximum adsorption capacity was 138.88 mg (Pb(II)) /g (dried biomass). Biosorption of Cd(II) by dried biomass of Bacillus badius AK was found to have maximum biosorption capacity of 131.58 mg (Cd(II)/g (dried biomass). The continuous column mode operation of dried biomass of Bacillus badius AK in biosorption of Pb(II) was observed with higher breakthrough capacity as compared to the batch process. The dried (pretreated) biomass of Bacillus badius AK has much potential as a biosorbent for removal of heavy metals such as Pb(II) and Cd(II) from aqueous solution at lab scale. Additionally, it is an economical and promising substitute of biosorbent for heavy metal removal as compared with the existing conventional methods of biosorption.Item Anaerobic digestion of water hyacinth : Effect of pretreatment and co-digestion on biogas production(2018) Barua, Visva BharatiWater hyacinth is considered to be the world’s worst aquatic due to its phenomenal reproduction potential. It can grow within a week and cover an entire freshwater body by forming thick dense mats. These thick dense mats hamper the aquatic ecosystem alongwith the health, livelihood and recreation of human beings. Water hyacinth is difficult to manage as it can re-grow miraculously even if it is completely eradicated. Presence of cellulose and its availability in abundance makes water hyacinth an attractive feedstock for biogas production through anaerobic digestion. Biogas production from water hyacinth can effectively manage the aquatic weed as well as mitigate environmental pollution which is caused by burning of fossil fuel. But the presence of lignin in water hyacinth makes hydrolysis the bottleneck of anaerobic digestion thereby delaying the hydrolysis phase and producing decreased amount of biogas. Therefore pretreatment of water hyacinth is essential for accelerated hydrolysis period and enhanced biogas production. In this study, thermal, electrohydrolysis and biological (microbial) pretreatment were investigated to enhance solubilisation of water hyacinth. Hot air oven pretreatment of water hyacinth at 90ºC for 1h demonstrated the highest solubilisation and biogas production when compared to the other pretreatment techniques. Even mono-digestion of water hyacinth produces lesser amount of biogas therefore co-digestion of water hyacinth is essential to balance the nutrients and dilute the toxic inhibitors. During the BMP assay F/M ratio 2 was observed to be ideal for untreated water hyacinth whereas for the pretreated water hyacinth F/M ratio 1.5 was observed to be ideal. Co-digestion of water hyacinth was tried not only with cow dung as inoculum but also with other organic wastes (i.e., food waste, Hydrilla verticillata, banana peels) with and without pretreatment. Pretreatment and anaerobic co-digestion of water hyacinth not only enhanced the quantity of biogas production but also the quality of the produced biogas by increasing the percentage of methane content. At last, a novel anaerobic digester was designed, fabricated and operated in continuous mode. The novel anaerobic digester proved its immense prospective in treating water hyacinth in untreated, pretreated or co-digested form. The design of the novel anaerobic digester is proficient in minimising the cost, difficulty in operation and manages space constraint when compared to the traditional two stage anaerobic digesters with mixing operation.Item Microalgae as candidate for phenol bioremediation and biofuel production(2018) Das, BhaskarPhenol is a xenobiotic released in wastewaters of industries as coal industries, phenol manufacturing, pharmaceuticals, dying, petrochemicals, pulp mill etc. Owing to high ecological toxicity risks of phenol it is considered a priority pollutant requiring efficient phenol removal technologies from industrial wastewater. Biological treatment of phenol has gained wide interest owing to its advantages of complete phenol mineralization and cost effectiveness. Phenol degradation capabilities of bacteria and fungi have been profoundly studied compared to that in algae. Six algal strains were screened for phenol degradation ability of which Spirogyra, Closterium and two unidentified algae were isolated from sewage wastewater, one diatom strain BD1IITG was isolated from petroleum refinery wastewater and Chlorella Pyrenoidosa (NCIM 2738) was obtained from National Collection of Industrial Microorganisms, Pune.Item Evaluation of Aniline formaldehyde condensate polymer in two different forms for heavy metals and anionic dyes adsorption from wastewater(2018) Terangpi, PraisyAdsorption technique for wastewater treatment is considered to be the most economically feasible method. Various literatures reported the removal of dyes, heavy metals, etc., by adsorbents such as activated carbon, fly ash, fruit peels, polymeric adsorbents, clay materials, etc. Removal of metal ions and dyes by functionalized polymer like amine groups have been found to be one of the most efficient functional groups for adsorption in which the mechanisms have been attributed to the formation of complexes between the amine groups present on the adsorbents and the adsorbates to be removed. The objective of the thesis was to investigate anionic dyes removal by two amine coated polymer – a) AFC-silica (aniline formaldehyde coated silica gel) and b) PANI-jute (short chain polyaniline coated jute fiber) and to synthesize a new support less amine based polymer (modified-AFC) with detail characterization and study the removal conditions of heavy metals from very dilute solution. Electrostatic attraction with protonated amine group and hydrophobic-hydrophobic interaction and hydrogen bonding were responsible for dye uptake besides which dye molecular weight was also found to play an important role. The support less amine polymer (modified-AFC) was powdered mesoporous material with round shaped clusters. Batch adsorption experiments of chromium and mercury in single system and lead, coper and chromium in multicomponent system was carried out from aqueous solution under operating conditions. Ion exchange as well as redox interaction between chromate ion and protonated amine group of the polymer was found to be the key factor for chromium adsorption. The residual concentration of total chromium (1.74 mg/L) was found within the discharge limit (2 mg/L) of wastewater which supports the adsorbent application in real wastewater treatment. For mercury removal interaction between protonated amine group and anionic species of mercury was the main adsorption mechanism. In multicomponent metal system adsorption due to the coordinate bond between metal ions and nitrogen present in amine group of modified-AFC was the main factor for the removal mixed metals. Finally, the results obtained from this research work gave an insight view of an efficient amine based polymer with and without any supporting material as a high potential adsorbent.
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