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A simulation model of high ash Indian coal based Fluidized Bed Gasifier has been developed using Aspen Plus simulation software and the predicted results were validated against the experimental data available in literature for three different types of coals having different ash content which was as high as 48.9%. The hydrodynamic parameters as well as reaction kinetics were both adapted from standard literature data. To complete the gasification modeling, various unit operation blocks available in Aspen Plus was used. The three different coal samples which consisted of different proximate and ultimate analysis values was used for the simulation. Parameters such as steam to coal ratio and temperature were varied while the coal feed rate and air to coal (A/C) ratio were kept constant throughout the simulation process as per the standard literature data. The model predicted very well in determining the final synthesis gas compositions. The simulation experiment also yielded various more critical information which otherwise was not found in the followed literature. The simulation shows that the production of H2 increases with higher steam to coal ratio but follows a decreasing trend after a certain temperature while the amount of CO and CH4 was found to increase with temperature but follows a slight average decreasing trend on increasing the steam to coal ratio. The amount of CO2 formed was found to have increased in the temperature range of 750–950°C which further decreased with the increasing temperature. The carbon conversion efficiency was also found to have increased with increasing temperature as well as steam to coal ratio.

The hydrodynamic behavior of a 2-D gas–solid fluidized bed has been studied using computational fluid dynamics (CFD) software package ANSYS Fluent. The modeling results were validated using the experimental data carried out in a lab-scale perspex column based fluidized bed having a diameter of 0.1 m and height of 0.62 m. The modeling studies showed a very good resemblance with the experimental observations. Studies were carried out by using 0.0003 m biomass fine powder having a density of around 1242 kg/m3 at different inlet gas velocities. Eulerian-Eulerian model approach along with the kinetic theory of granular flow is used for simulating the gas–solid fluidization behavior. In the present work, the effects of inlet gas velocity, pressure drop and bed expansion ratio was studied. The minimum fluidization velocity condition was predicted by using the simulated contour plot of the computational software. The momentum exchange coefficients were calculated using Syamlal-O’Brien functions. The comparison study showed that the CFD simulation of a gas–solid fluidized bed can be used effectively for the designing and operation of a lab-scale fluidized bed column. Moreover the simulation studies would also help in the scaling up of the fluidized bed further for industrial usage.

A typical combination of spiral wound ultra-filtration and spiral wound reverse-osmosis membranes were used to treat grey water obtained from washing machine discharge in order to recover the surfactant solution as well as water both of which could be reused for another couple of washes. The process leads to the separation of dirt and dust particles from the grey water using the UF process and later the surfactant solution and water is separated from the mixture using the reverse osmosis membrane. Various backwash and backwash-backflush methods were used to increase the membrane performance by decreasing the fouling problems which generally occurs in such types of membranes. These backwashing procedures were found to have enhanced the life of the membrane by cleaning the membranes. The TDS and turbidity of the solution mixtures were analyzed by conductivity meter and turbidity meter respectively and the results obtained from these instruments provided a good idea regarding the separation processes. The UF membranes could decrease the turbidity of a dirty mixture solution but allows the surfactant solution to pass though it which is finally treated using the RO membranes which could decrease both the turbidity and TDS of the solution. The experiment provides a comprehensive idea related to the treatment of grey water which could help in better waste water reuse as well as economic ways of reusing detergents for subsequent washes.

A detailed study was conducted to investigate the applicability of various ligno-cellulosic biomasses for clean energy generation purposes using thermo-chemical treatments like gasification, pyrolysis etc. The samples were selected depending on their robust availability in the form of unutilized wastes. In the present investigation, characteristics data of seven forest wood residues, one agricultural residue and one household waste have been reported. The biomasses were analysed by various physical and chemical methods to characterize their composition and structure. The proximate and ultimate analysis of the biomass samples were also carried out. Characterization techniques like HPLC, DSC, FTIR and CHNS elemental analyser were also carried out and presented in this article. The high heating value (HHV) of these biomasses were analysed to be as high as 21.42 MJ/kg. This detailed study will provide a comprehensive idea about the feasibility of the biomass samples found extensively in the areas of Northeast India for generation of clean energy using gasification, pyrolysis etc.

Heavy metal-contaminated water can be effectively treated using adsorbents made from abundantly available biomass. The present investigation was carried out to adsorb Cd(II) from synthetic solution by banana pseudo-stem (BP) and Moringa oleifera stem bark (MB). Adsorption efficiencies of both adsorbents were studied in the batch reactor by conducting experiments to determine the consequences of changes of pH, adsorbent dosages, initial Cd(II) concentrations, incubation time, and temperature. The process parameters were tuned to attain the highest possible removal percentage. The characterization of the adsorbents was performed by utilizing Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) for the fresh and metal-loaded adsorbents. Atomic absorption spectroscopy (AAS) was employed to calculate the amount of Cd(II) in an aqueous solution. The experimental data were entirely consistent with the pseudo-second-order model for BP and MB. The findings of the study illustrated the better adsorption efficiency of BP-derived adsorbent (≈ 99%) at optimum conditions over the MB (≈ 97%), and the corresponding adsorption capacities were 11.98 and 7.04 mg/g, respectively. The 4 (four) well-known isotherm models were attempted both in linear and non-linear forms. BP (R

Introduction: It is a well-known fact that the demand of water increases with population increase. W.H.O. reported that by 2025, half of the population will be not able to have a clean source of water (1). Thus, water has to be used judiciously and should not be wasted. Estimates vary, but a typical household use about 80-100 gallons of water per day. The largest use of water in every house is for washing clothes, bathing, toilet flush, washing dishes. Urban waste water which includes water from bath, shower, hand basins, washing machine, dishwashers and kitchen sinks, but excludes streams from toilets is called grey water (2). Grey water which is also primarily discharged from washed laundry contains high in surfactants and is also very high in suspended solids, turbidity and oxygen demand. When the grey water is released without treatment it can cause environmental pollution and serious threat to living being. Currently treatment of laundry water is a challenge because of rapid population growth and also it is not accompanied by infrastructure improvements, especially in the field of sanitation. It is important that wastewater should be treated in order to save water as a future source and protect the environment from pollution. Previously grey water treatment was done physically where pollutants from grey water were removed by coarse sand and soil filtration (3). Now with the advancement of membrane-based water treatment technologies, such treatment methods have come into focus (4). The main object of this study to recover the valuable surfactant solution and generate potable water both of which could be reused again thereby leading to a cost effective, sustainable and environment friendly process. Methods: An experimental setup has been developed which uses a spiral wound UF membrane that essentially removes the suspended matter from the grey water that was taken as the feed solution. The reject from this membrane is recycled back to the feed tank whereas the permeate enters a spiral wound RO membrane where the surfactant is removed from the solution thereby allowing potable water pass as a permeate. Both the membrane modules were optimized for its operating pressure and flowrates. Results & Discussions: The collected grey water used for the experiment was found to have TDS of 749 ppm, Turbidity of 106 NTU and BOD of 290 mg/l. On treating it using the UF membranes, the recovered surfactant was found to have a TDS of 830 ppm, turbidity of 12.6 NTU and BOD of 110 mg/l indicating the collection of concentrated surfactant solution. The potable water which was collected later as RO permeate tested to have a TDS of 25 ppm, turbidity of 0.41 NTU and BOD of just 20mg/l indicating that the RO permeate is now potable. Conclusions: The process leads to an effective separation process where the grey water obtained from washing machine was first cleaned of dirt materials using UF membranes and further separating the surfactant solution from the mixture and yielding potable water. The recovered concentrated surfactant solution as well as potable water could be reused again for future washes. The process thus leads to conservation of water too in addition to being cost effective and environment friendly. Keywords: Grey water treatment; surfactant recovery; potable water recovery; UF and RO membranes. Acknowledgment: The authors would like to thank the Vice Chancellor, Tripura University for providing necessary research facility. References 1. WHO. No Title [Internet]. W.H.O. 2019 [cited 2021 Sep 11]. Available from: https://www.who.int/news-room/fact-sheets/detail/drinking-water. 2. Reang S, Nath H. Grey water treatment with spiral wound UF and RO membranes. Mater Today Proc. 2021 Jan 1;46:6253–9. 3. A. Carmalin Sophia Harjeet Nath and N. V. S. Praneeth. Synthesis of nano-porous carbon from cellulosic waste and its application in water disinfection. Curr Sci (Research Commun. 2016;111(No. 8):1377. 4. Venkatesh T, Senthilmurugan S. Grey water treatment and simultaneous surfactant recovery using UF and RO process. Sep Sci Technol. 2017. &nbsp

In the current study, activated carbons (ACs) prepared from some biomasses available in North East India were tested for its antibacterial capacity. The biomasses used for the preparation of ACs we...

Nanotechnology is one of the key and most promising technologies of the 21st century. The materials at nanoscale, i.e. nanomaterials, exhibit various novel properties when compared to their bulk counterparts mainly due to quantum confinement effect and large surface area to volume ratio. Various studies have revealed that these novel properties, which essentially make nanomaterials unique, might be one of the main reasons for their potential toxicity. Day by day, there has been various intended as well as non-intended exposure of human beings to nanomaterials. However, currently very few regulatory guidelines on the testing, evaluation, and disposal of nano-particulate materials are available. Although developed countries and many developing countries have invested for research in nanoscience and nanotechnology, the studies are not adequate on social justice, ethics, civil liberties, and good laboratory practice including proper nanomaterial disposal issues. Nanotechnology practitioners are also not updated with the latest critical issues associated with nanomaterials. This chapter will discuss various issues and challenges in nanotechnology at global level and will primarily focus on various similar issues and policies which must be followed by the technologists, engineers, and scientists of developing countries, like India. The workforce of the developed and developing countries must learn about the adverse effects of working with nanomaterials.

In the current study red mud is used as a medium to adsorb the hazardous exhaust gas containing gaseous fluorides coming out of aluminum industries as a measure to control environmental pollution. A high temperature fluidized bed reactor is used in this case which can be operated at around 300°C using a ceramic heater connected to the fluidized bed column. Optimally sized red mud powder having good fluidization quality is used to check the adsorbing properties of the gaseous fluorides on the metallic components present in red mud. Various characterization techniques like PSA, TGA-DTA, FT-IR, ICP-MS, FESEM, EDX and XRD are used. These characterization techniques proves the reaction between the metallic components present in red mud with the gaseous fluorides due to the presence of AlF 3 , FeF 2 , FeF 3 and NaF observed in the products. This report thus proves the applicability of fluidized bed reactor in treating the gaseous exhaust containing fluorides using red mud which otherwise is considered as a waste in the aluminum industry itself.

article i nfo Article history: Red Mud (RM) is fluidized at different temperatures in a fluidized bed reactor (FBR). The phase composition and structural transition of RM fluidized at different temperatures are investigated. RM is treated in the FBR at differ- ent temperatures and above minimum fluidization velocity. The characteristic properties of RM treated in FBR at different temperatures are analyzed using XRD, TGA-DTA, PSA, FESEM, FT-IR and BET apparatus. It is observed that the different components of RM decompose on treatment of high temperature. The results thus obtained from RM treated at room and at higher temperatures are found to be much more promising where the temper- aturerequiredforthe decompositionofcertaincomponentsismuch lessthantheconventional heatingmethods. It is observed that gibbsite (Al(OH)3) decomposes into Al2O3 &H 2O and calcite decomposes into CaO and CO2 at higher temperatures. The particle size of treated RM is also analyzed where the particle size is found to increase initially and then decrease with the increase in temperature. The results obtained will thus provide an important base for the comprehensive utilization of RM for different applications.

Red Mud (RM) is a solid waste product obtained from aluminum industries via Bayer’s process. India is one of the largest producers of RM producing around 4 million tons annually. Its disposal is one of the major concerns as it is highly alkaline in nature and is a potential threat to air, water and land. Currently RM is being dumped on land or in RM ponds near the alumina refineries and with the cost of the land going high it is becoming a big problem for the industries. Due to the differences in the ore type in its production process, there is a variation in the mineralogical composition between the residues from India and other countries. Its properties such as iron content in the form of ferric oxide (Fe2O3), high surface area etc. makes it attractive potential reactants for many reactions. In this paper the structural and phase compositions of RM is being studied with the help of PSA, XRD, FESEM, EDX, BET and FT-IR techniques.

The present study deals with the preparation of new cellulosic catalyst materials, viz. paper and textile industry waste. Activated nano-carbons were prepared from these waste materials using thermo-chemical method. Nano-silver particles (AgNP) were embedded into the synthesized carbons to incorporate antimicrobial properties. The catalyst materials were characterized using FESEM-EDX, XRD, FTIR, etc. The characterization results showed that the materials were nanoporous and silver was uniformly distributed throughout the catalyst. The suitability of the catalyst as an antimicrobial agent was studied using pour plate technique. The main advantages of the disinfecting materials over conventional materials were: (i) only small quantities (mg) of catalysts are required to deactivate microorganism for up to 1 litre of water; (ii) time required for more than 99% disinfection is less (60 min); (iii) carbon has been synthesized from cellulosic wastes which otherwise would pollute the environment, hence it is a waste recycling process. The carbons exhibited more than 99% E. coli removal within 60 min.