Woody lignocellulosic biomass is identified as a promising feedstock for liquid biofuel production since it is available throughout the year at a low cost in addition to carbon negative emission capability and no scrutiny as a food source. However, using woody biomass incurs expensive and energy-intensive pretreatment and processing steps in fuel production. This chapter covers woody biomass processing through biochemical routes for liquid transportation fuels (bioethanol and biobutanol) and aviation fuel production. It includes sources of various hardwood and softwood species alongside their compositions. Available pretreatment and hydrolysis techniques and different biochemical conversion approaches are discussed. Lastly, this chapter critically analyzes different studies to identify their processing approaches and operating conditions used for liquid biofuel yield enhancement. It is seen that biochemical conversion fermentation is primarily used for bioethanol and biobutanol production, whereas various thermochemical conversion processes are dominated in bio-jet fuel production from woody biomass. This critical discussion can be helpful for future liquid biofuel production planning, scale-up, and energy policy preparation.

Per- and poly-fluoroalkyl substances (PFAS) are concerning contaminants due to their ubiquity, persistence, and toxicity. Conventional PFAS water treatments such as granular activated carbon are limited by low adsorption rates and capacities. Carbon-based nano-adsorbents with enhanced surface areas address these limitations but are hindered by their high cost and toxicity. Cellulose nanocrystals (CNC) are promising PFAS adsorbents due to sustainable sourcing, large surface areas, and amenable surface properties. In this study, CNC was synthesized from the agro-food waste, apple pomace (APCNC), and coated with Moringa oleifera cationic protein (MOCP) aqueous extract to produce MOCP/APCNC for the removal of perfluorooctanoic acid (PFOA) from water. APCNC and MOCP/APCNC were manufactured, characterized, and utilized in PFOA batch adsorption kinetics and equilibrium trials. APCNC was successfully produced from apple pomace (AP) and determined through characterization and comparison to commercial CNC (CCNC). APCNC and MOCP/APCNC exhibited rapid PFOA adsorption, approaching equilibrium within 15 min. MOCP coatings inverted the MOCP/CNC surface charge to cationic (−15.07 to 7.38 mV) and enhanced the PFOA adsorption rate (2.65 × 10−3 to 5.05 × 10−3 g/mg/s), capacity (47.1 to 61.1 mg/g), and robustness across varied water qualities. The sustainable sourcing of APCNC combined with a green surface coating to produce MOCP/CNC provides a highly promising environmentally friendly approach to PFAS remediation.

This study aimed to investigate the effect of chemical-free two-stage hydrothermal and mechanical refining pretreatment on improving the sugar yields during enzymatic hydrolysis of forest residue biomass (FRB) and optimize the pretreatment conditions. Hot-water pretreatment experiments were performed using a central composite design for three variables: temperature (160–200 °C), time (10–20 min), and solid loading (10–20%). Hydrothermally pretreated biomass was subsequently pretreated using three cycles of disk refining. The combined pretreatment was found to be highly effective in enhancing sugar yields during enzymatic hydrolysis, with almost 99% cellulose conversion for biomass pretreated at 213.64 °C, 15 min, and 15% solid loading. However, the xylose concentrations in the hydrolysate were found to be low under these conditions due to sugar degradation. Thus, less severe optimum pretreatment conditions (194.78 °C, 12.90 min, and 13.42% solid loading) were predicted using a second-order polynomial model. The response surface model optimized the hydrothermal pretreatment of FRB and predicted the glucan, xylan, and overall conversions of 94.57%, 79.78%, and 87.84%, respectively, after the enzymatic hydrolysis. The model-predicted biomass conversion values were validated by the experimental results.

Marine Protected Areas (MPAs) are widely used tools for conserving coastal and marine biodiversity and ecosystem health. However, the goal of declaring and managing at least 10% of coastal and marine waters as MPAs has not been achieved in Bangladesh and many other countries. This study aimed at prioritizing the potential areas for MPA delineation in the south-west coastal zone of Bangladesh. The study also examined the socio-economic status, environmental and ecological characteristics of the study areas. Data on socio-economic, environmental, ecological, and management variables were collected through intensive field surveys from August 2023 to December 2023. The data were integrated using a multi-criteria analytical technique. Fishing was identified as the primary occupation for all fishermen surveyed, with secondary occupations including fish selling, marketing, and drying activities. The fishing areas for fishermen from the three survey sites were mainly concentrated in the offshore area. All three areas were identified as biodiversity hotspots, with Kuakata coast showing the highest species diversity, followed by Salimpur and Sandwip coasts. The study revealed that the Kuakata coast has the highest conservation importance, especially for IUCN red-listed species, juvenile fisheries species, and megafauna species. Salimpur coast is important for the conservation of saltmarshes, mangroves, and their dependent communities, while Sandwip is crucial for juvenile fish species conservation. Based on socio-ecological criteria, Kuakata was recommended as the most potential site for MPA delineation, followed by Salimpur and Sandwip. Implementing these recommendations can improve the management and execution of existing MPAs by focusing conservation efforts on areas with the highest biodiversity and ecological importance, ensuring better protection for vulnerable species, and enhancing the sustainability of local fishing communities. This, in turn, will ultimately enhance biodiversity conservation and ecosystem health in the southwest coastal area of Bangladesh.

Carbon capture storage and utilization (CCSU) has the potential to become a key tool to mitigate climate change, thus, aiding in achieving the objectives of the 2015 Paris Agreement. Even though the relevant remediation technology has achieved technical maturity to a certain extent, implementation of CCSU on a larger scale is currently limited because of non-technical parameters that include cost, legalization, lack of storage reservoir, and market mechanism to penalize CO2 emitter. Among these, cost emerges as the primary barrier to the dissemination of CCSU. Hence, necessary policy frameworks and incentives must be provided by governing agencies to enable faster dissemination of carbon capture and utilization (CCU) and carbon capture and storage (CCS) globally. Meanwhile, strict implementation of a carbon tax across nations and market demand for products generated using captured CO2 can aid in the fast adoption of CCU and CCS. This review assessed the economic feasibility and sustainability of CCS and CCU technologies to identify the barriers to commercializing these technologies.

Absorption of CO2 from flue gas using solvents has been considered an effective process although its commercial implication still requires rigorous study. In this work, detailed process flowsheets of monoethanolamine (MEA), diethanolamine (DEA), and chilled ammonia solvent systems were developed in Aspen Plus to determine the maximum CO2 capture efficiency by varying process parameters. The effects of several process parameters, such as absorber stages, temperature, regeneration duty of the solvent, and blended solvents, were evaluated through sensitivity analyses. The results showed that 15 stages and 30 °C temperature in the absorber column resulted in the maximum CO2 capture efficiency using alkanolamine (MEA and DEA) solvent, but a lower temperature (5 °C) was needed for the maximum CO2 capture efficiency using chilled ammonia. Moreover, DEA had a 10

The ultrasonic-aided co-precipitation method was used to create SnO2-TiO2 nanocomposite particles. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and UV-vis spectroscopy were used to characterize the nanocomposite particles. XRD patterns revealed the crystalline structure of particles and the average particle size determined by Debye Scherrer’s equation was found to be 11.355, 4.9577, and 4.333 nm for TiO2 nanoparticles, SnO2 nanoparticles, and SnO2-TiO2 nanocomposites, respectively. The Ti, Sn, and O species were confirmed to exist by energy-dispersive X-ray spectroscopy (EDS). The UV absorption peaks at 288, 305, and 350 nm were attributed to SnO2, TiO2-SnO2, and TiO2 respectively. The photocatalytic aspect was investigated in a model organic contaminant (methyl orange). Data obtained by the above-mentioned characterization methods confirmed the superior photocatalytic activity of SnO2-TiO2 nanostructure than SnO2 or TiO2 alone.

Rapid population growth creating an excessive pressure on the marine environment and thus monitoring of marine ecosystem is essential. However, due to high technical and financial involvement, monitoring of coastal ecosystem is always challenging in developing countries. This study aims to develop an integrated coastal ecosystem monitoring system that combines scientific sampling, numerical model simulation and citizen science observations to monitor the coastal ecosystem of Bangladesh. This concept of integrated monitoring approach was piloted from January 2022 to April 2023 at the South East coastal zone of Bangladesh. Scientific sampling and numerical model simulations were performed for temperature and salinity data collection. Citizen science approach was employed to collect data on environmental conditions, fisheries, plankton, other marine resources, and plastic pollution. Numerical model simulations and citizen scientists observations of temperature and salinity showed good agreement with the scientifically collected data. In addition, citizen scientists observations on fisheries, plankton, other marine resources and plastic pollution were also in line with the existing database and previous studies. The proposed integrated monitoring approach presents a viable technique, creating a new avenue for coastal and marine ecosystem monitoring where infrastructural facilities are limited.

Phytoplankton form the base of food chain and play a key role in maintaining the global climate system. However, very limited knowledge is available about the phytoplankton ecology of Bangladesh coast which is a representation of sub-tropical coastal ecosystem. Thus, this study aimed to understand the spatial and temporal variability of phytoplankton community in-relation to environmental variables in the South East coast of Bangladesh. Monthly data on essential oceanographic variables (i.e. temperature, salinity, dissolved oxygen, turbidity, silicate, nitrate and phosphate) and phytoplankton species abundance were collected from January 2022 to December 2022. We found a strong spatial and temporal variability in essential oceanographic variables and phytoplankton community compositions in Naf – Saint Martin Peninsula of Bangladesh. Estuarine ecosystem is characterized by high nutrients and low salinity while offshore ecosystem was found with comparatively low nutrients and high salinity. About 154 phytoplankton species were identified from the study area through year round sampling events. In the estuarine ecosystem Skeletonema marino, Coscinodiscus centralis, Coscinodiscus argus and Coscinodiscus traducens were found as the major contributing species at the estuarine ecosystem while Chaetoceros radican, Tripos trichoceros, Cylindrotheca Closterium, Chaetoceros convulutus, Tripos muelleri, and Cyclotella striata were found as the major contributing species at the offshore ecosystem. Our study found that 6 explanatory variables (i.e. temperature, salinity, turbidity, silicate, nitrate and phosphate) jointly explained about 78% variability in phytoplankton community dynamics. Nitrate concentration explained maximum variability (19%) followed by phosphate (17%), salinity (15%), silicate (12%), turbidity (10%) and surface temperature (5%). This study will play a key role in understanding the spatial and temporal variability of phytoplankton dynamics in the sub-tropical coastal ecosystem.

Methanol is expected to be a possible solution for reducing global greenhouse gas emissions and minimizing the dependency on fossil fuels. This paper presents a systematic approach of methanol (MeOH) production from industrial waste gases including flue gas (FG) and coke oven gas (COG) that are considered an important threat to the environment. The impact of process parameters, including dimensional parameters (length, diameter, and number of tubes) and operational parameters (reactor temperature, pressure, and thermal fluid temperature) over the MeOH synthesis, are investigated by Aspen Plus. Firstly, the synthesis process is designed and optimized using syngas (SG) as a feed material. Secondly, by replacing the feed material with FG and COG, methanol production variability is investigated and demonstrated for the same optimized process. Afterward, an efficient heat exchange network system is developed for all three different processes using Aspen Energy Analyzer. The optimized dimensional parameters of the MeOH synthesis reactor are determined to be a length of 12 m, a diameter of 0.06 m, and 5000 tubes for achieving a conversion rate of 75%. Meanwhile, the optimized operational parameters are identified as a reactor temperature of 209 °C, reactor pressure of 70 bar, and thermal fluid temperature of 196 °C. Furthermore, the influence of the stoichiometric number (SN) on the process was observed with higher SN values resulting in increased hydrogen (H2) concentration and an improved forward reaction of MeOH synthesis, leading to higher conversion rates. The findings and insights gained from this study can serve further improvements and advancements in MeOH synthesis processes.

Per- and polyfluoroalkyl substances (PFASs) are aqueouscontaminantsassociated with serious health consequences. Conventional PFAS adsorbentsare limited by slow kinetics and low short-chain PFAS uptake, drivinginterest in high-performing alternatives. Here, beta-zeolites wereinvestigated for short- (= C8) PFASremoval. beta-zeolites with high (CP811C) and low (CP814E) silica/aluminaratios were coated with cetyltrimethylammonium bromide (CTAB) or poly-(diallyldimethylammoniumchloride) (PDADMAC) to enhance short- and long-chain PFAS retention,represented by heptafluorobutyric acid (PFBA) and perfluorooctanoicacid (PFOA). PFAS rapidly adsorbed onto beta-zeolites, reachingequilibrium within 1-2 h. Greater PFOA uptake (91.87 vs 57.77mg/g) was reported onto the silica-rich beta-zeolite, CP811C. Whilethe CTAB coatings reduced PFOA adsorption capacity by 58.7%, the PDADMACcoatings increased PFBA adsorption capacity by 51.3%. On unmodifiedCP811C, PFOA and PFBA exhibited maximum adsorption capacities of 181.87and 27.89 mg/g, respectively. Fast and high-capacity adsorption make beta-zeolites highly promising PFAS adsorption technology.

Fossil fuel reserve is declining gradually which results in serious scarcity of fuels and chemicals across the globe. In addition, fossil fuels' versatile usage is also responsible for the ever-increasing global warming. All together a potential solution to those two problems could be the use of lignocellulosic biomass for fuel production because this alternative energy source is renewable, inexpensive, and readily available. Moreover, this biomass has neutral emission during the total biomass conversion process for fuels and chemicals coproduction. This chapter discusses bioethanol production from lignocellulosic biomass in two conversion routes - biochemical and hybrid conversion (combination of thermochemical and biochemical conversion) route. In the first biorefinery route, non-woody lignocellulosic biomass is converted into bioethanol through a biochemical conversion process that involves the conversion of biomass carbohydrates to sugars and subsequent fermentation by genetically modified Saccharomyces cerevisiae to bioethanol. The second biorefinery route uses gasification and consecutive synthesis gas fermentation in presence of Clostridium species for bioethanol production from the woody lignocellulosic biomass. In each route, the biomass pretreatment process, biomass sugar conversion process, and down-stream separation process are discussed in detail. Pretreatment processes by microbial consortia are discussed to show their impact on biomass crystallinity reduction and surface area increase in first route. Then separate hydrolysis and fermentation (SHF) process is utilized to hydrolyze lignocellulosic sugar and finally fermentation of all soluble sugars to bioethanol is discussed in the biochemical conversion process. On the contrary, in hybrid conversion process, gasification of woody biomass is carried out at first and later synthesis gas fermentation is discussed for bioethanol production. As a result, this chapter enables one to understand the details of process design steps required for second generation bioethanol production based on two large microbial consortia, genetically modified S. cerevisiae yeast and Clostridium bacteria species.

Phytoplankton are the floating microscopic organisms which form the base of aquatic food chain, and their ecology is controlled by biotic and abiotic variables. However, a little is known about the response of phytoplankton to changed environmental conditions especially in the sub-tropical regions. Therefore, this study aimed to understand the response of phytoplankton community in variable temperature and salinity conditions in the Naf River estuary of Bangladesh. Phytoplankton, temperature and salinity data were collected from the Naf River estuary of Bangladesh from February 2022 to December 2022. Predicted data of temperature and salinity under two climate change scenarios were also gathered from a hydrodynamic model. Response of phytoplankton to different temperature and salinity scenarios were then analyzed by using a logistic model. This study identified about 154 phytoplankton species from the study area. Temperature had significant negative impacts on the 50 phytoplankton species while 83% species were correlated to the change in salinity. About four phytoplankton species disappeared under the changed environmental conditions. Abundance of one species significantly reduced (50% reduction) while environmental conditions were changed. About 18 phytoplankton species responded positively to the changed environmental conditions. This study provides necessary insights to understand the consequences of climate change on phytoplankton ecology in the sub-tropical ecosystems.

As the global demand for sustainable energy increases, lignocellulosic (such as agricultural residues, forest biomass, municipal waste, and dedicated energy crops) and algal (including macroalgae and microalgae) biomass have attracted considerable attention, because of their high availability of carbohydrates. This is a potential feedstock to produce biochemical and bioenergy. Pretreatment of biomass can disrupt their complex structure, increasing conversion efficiency and product yield. Therefore, this review comprehensively discusses recent advances in different pretreatments (physical, chemical, physicochemical, and biological pretreatments) for lignocellulosic and algal biomass and their biorefining methods. Life cycle assessment (LCA) which enables the quantification of the environmental impact assessment of a biorefinery also be introduced. Biorefinery processes such as raw material acquisition, extraction, production, waste accumulation, and waste conversion are all monitored under this concept. Nevertheless, there still exist some techno-economic barriers during biorefinery and extensive research is still needed to develop cost-effective processes.

Bangladesh earned lower middle-income country status in 2015 due to satisfactory level of (previous) continuous economic growth. Later the country entered into the United Nations' list of Least Developed Countries (LDC) in 2018 and is on track to achieve the middle-income country status by 2024. Key criteria for this achievement will be the nationwide rapid sustainable economic growth in coming years. Economic advancement of the country will be largely depended on its energy sector flourish, more explicitly on electricity generation. At present more than 90% of the electricity in Bangladesh is produced from fossil fuels (from imported and national reserve) such as diesel oil, furnace oil, natural gas, and coal. Irrational burning of these fossil fuels expedites the rapid depletion of national coal and natural gas reserve as well as put additional burden on national economy due to oil import, threatening continuous electricity supply for the future economic prosperity. At the same time deterioration of environmental quality as a whole is also associated with this fossil fuels usage. Thus, to ensure an unremitting supply of electricity in coming days, the country needs to have both sustainable and environment friendly energy sources and technologies. Hence, this article discusses the potentiality of various renewable energy resources (solar, hydro, biomass, and wind), their current contribution in country's energy sector, and relevant challenges for utilization. In addition, this paper includes the future government policies for renewable energy integration with the conventional energy generation for overall energy security attainment and economic development of Bangladesh.

Lignocellulosic biomass are plentiful low-cost resources available in nature having significant bioenergy potential with a low environmental burden. Sawdust, one of the major low-value byproducts of wood processing facilities, is such an abundant feedstock. Brewer‘s spent grains (BSG), a major byproduct of the brewing industry, is another high potential feedstock for bioenergy production. The objective of this work is the co-production of biogas and hydrochar using integrated anaerobic digestion (AD) and hydrothermal carbonization (HTC) processes from a mixture of sawdust (from sugar maple) and brewer‘s spent grains (BSG). A two-step mechanical hydrothermal pretreatment, combining liquid hot water pretreatment followed by disk milling, was used to reduce the biomass recalcitrance. Various mixtures of raw and pretreated biomass were investigated for biogas production AD for 21 days. The pretreatment was effective in increasing the biogas yield during the AD process. In the case of sawdust, the biogas yield increased by 3.3 folds compared to raw biomass. The co-digestion resulted in high biogas yield, with the maximum biogas yield of 611.1 mL/g VS for a mixture of raw BSG and pretreated sawdust at a 1:4 ratio. The proximate and ultimate analysis of hydrochar obtained from the hydrothermal carbonization of the digestatewere performed to identify the carbon densification and to study the thermogravimetric analysis.

Due to the boon of globalization, the aviation industry is booming at a rate higher than ever, depleting the limited fossil fuel resources while taking great toll on the environment. Hence, it is imperative to search for alternate, renewable, and economically comparable resources of jet fuel. On that account, lignocellulose-based biofuel is gaining an increasing interest as a potential source of biojet fuel, showing a great promise for the reduction of operating cost and environmental impacts. However, the fuel obtained from biomass cannot be directly used for aviation purposes and must go through certain upgradation processes to meet the strict jet fuel requirements. Catalysts play a crucial role in different stages of upgradation including hydrogenation, hydrodeoxygenation, alkylation, hydroisomerization, hydrocracking, aromatization, CC coupling, etc. The present chapter summarizes the different types of catalysts along with their catalytic reaction mechanism used in the catalytic conversion of different biomass feedstocks to biojet fuel. The chapter also addresses the limitations associated with some catalytic processes with suggestions regarding possible future research directions.

This study is aimed to apply dry anaerobic digestion (DAD) for methane (CH4) enriched biogas production from unsorted organic municipal solid waste (MSW). Cumulative biogas production was monitored for 35 days of operation in batch digesters at fixed feedstock to inoculum (F/I) ratio 2. Anaerobic sludge (AS) and cow manure (CM) were used as inoculum in single and mixed modes. Several process parameters such as inoculum flow pattern (single layer, multilayer, and spiral), digestion temperature (25 to 40 °C), inoculation modes (single and mixed mode), and inoculation proportion (AS:CM = 1:1, 1:2, 1:3, and 2:1) were investigated to determine the optimum DAD conditions to maximize the CH4 laden biogas yield. The study of inoculum flow pattern showed that digester with multilayer inoculum configuration generated the maximum 555 mL cumulative biogas with the production rate of 195 mL/day (at 25 °C). Biogas production rate and cumulative biogas production were found to increase with a rise in temperature and the maximum values of 380 mL/day and 1515 mL respectively were observed at 37 °C. The mixed mode of inoculation containing AS and CM augmented the biogas yield at previously optimized conditions. Final results showed that digester with multilayer inoculum flow pattern at 37 °C produced 1850 mL cumulative biogas with 1256.58 mL CH4/kg volatile solid (VS) when the mixed inoculum was used at the AS:CM-1:2 ratio. Biogas production with this significant amount of CH4 justifies the use of the DAD process for energy (biogas) generation from widely available biomass feedstock (MSW), offering various advantages to the environment.