Waste to energy: An experimental study of utilizing the agricultural residue, MSW, and e-waste available in Bangladesh for pyrolysis conversion.

The paper aims to study different aspects of liquid fuel production through pyrolysis from agricultural residues, MSW, and e-waste available in Bangladesh. The abundant production of various crops generates massive amounts of residue such as rice straw, wheat straw, rice husk, jute stick, and sugarcane bagasse in Bangladesh have great potential for liquid fuel production for pyrolysis conversion. Bangladesh produces almost 25,000 tons of solid waste per day from urban areas, and Dhaka city alone contributes to one-quarter of all urban waste in the country. The biomass and waste-derived pyrolysis fuel can be successfully used in turbines, boilers, engines and upgraded to high-quality hydrocarbon transportation fuels through distillation. The concise data obtained from the study is anticipated to provide valuable information regarding the effective utilization of municipal solid waste and agricultural residues by using pyrolysis process so that further detailed work on these resources can pave a pathway towards scientific research and significant energy contribution in Bangladesh. The feasibility study has been conducted through physical properties, proximate analysis, elemental analysis, and thermogravimetric analysis of the selected agricultural residues, municipal solid wastes, and plastic e-wastes for pyrolysis conversion in Bangladesh. It has been found that polythene has a better thermochemical potential than rice straw (13.71 MJ/kg) owing to its high calorific value (46.41 MJ/kg). The foremost volatile matter obtained from plastic waste is 98.1 wt.%, and the minimum from rice husk is 57.19 wt.%. The maximum carbon amount is possessed by plastic waste (84.03 wt.%). The ultimate analysis showed that the MSW sample contains more sulfur content than agricultural residue and e-waste, whereas the case is the opposite in terms of oxygen. Rice husk and tire waste have the highest ash content, i.e., 19.70 and 4.38 (wt.%), respectively, indicating a significant amount of unwanted material. TGA examination of feedstock revealed that the majority of mass loss occurred between 250-450 °C for agricultural residue attributed to the release of volatile materials during the formation of char and the evolution of pyrolysis gases. For MSW samples, the range varies between 350-500 °C, which is the appropriate temperature for optimizing liquid oil production in plastic pyrolysis.

Snapshot fan beam coded aperture coherent scatter tomography.

We use coherently scattered X-rays to measure the molecular composition of an object throughout its volume. We image a planar slice of the object in a single snapshot by illuminating it with a fan beam and placing a coded aperture between the object and the detectors. We characterize the system and demonstrate a resolution of 13 mm in range and 2 mm in cross-range and a fractional momentum transfer resolution of 15%. In addition, we show that this technique allows a 100x speedup compared to previously-studied pencil beam systems using the same components. Finally, by scanning an object through the beam, we image the full 4-dimensional data cube (3 spatial and 1 material dimension) for complete volumetric molecular imaging.

Complementary coded apertures for 4-dimensional x-ray coherent scatter imaging.

X-ray scattering has played a key role in non-destructive materials characterization due to the material-specific coherent scattering signatures. In the current energy dispersive coherent scatter imaging systems, including selected volume tomography and coherent scatter computed tomography, each object voxel is measured at a single scatter angle, which suffers from slow acquisition time. The employment of coded apertures in x-ray scatter imaging systems improves the photon collection efficiency, making it promising for real time volumetric imaging and material identification. In this paper, we propose a volumetric x-ray scatter imaging system using a pair of complementary coded apertures: a coded aperture on the detector side introduces multiplexed measurement on an energy-sensitive detector array; a complementary source-side coded aperture selectively illuminates the object to decouple the ambiguity due to the increased parallelization for 4D imaging. The system yields the 1D coherent scattering form factor at each voxel in 3D. We demonstrate tomographic imaging and material identification with the system and achieve a spatial resolution ~1 cm and a normalized momentum transfer resolution, Δq/q, of 0.2.

Structured illumination for tomographic X-ray diffraction imaging.

Tomographic imaging of the molecular structure of an object is important for a variety of applications, ranging from medical and industrial radiography to security screening. X-ray diffraction imaging is the preeminent technique for performing molecular analysis of large volumes. Here we propose and demonstrate a new measurement architecture to improve the source and detector efficiency for diffraction imaging. In comparison with previous techniques, our approach reduces the required overall scan time by 1-2 orders of magnitude, which makes possible real-time scanning of a broad range of materials over a large volume using a table-top setup. This method, which relies on structuring spatially the illumination incident on an object moving relative to the X-ray source, is compatible with existing systems and has the potential to significantly enhance performance in an array of areas, such as medical diagnostic imaging and explosives detection.