A comprehensive review on anaerobic digestion of organic fraction of municipal solid waste

© 2020 Elsevier Ltd This article aims to comprehensively review the anaerobic digestion (AD) process utilising the organic fraction of municipal solid waste (OFMSW) substrate. The AD of OFMSW has received considerable attention due to its significant energy and nutrient recovery as well as its greenhouse gas (GHG) mitigation potential. AD is a biological process involving treating and stabilising organic matter in the absence of oxygen accomplished by a consortium of microorganisms and occurs under hydrolysis, acidogenesis, acetogenesis, and methanogenesis phases. The hydrolysis phase is recognised as the primary rate-limiting step. Thus, exploring the ways to speed up the hydrolysis process will maximise biogas production. The key factors affecting the digestion efficiency include feedstock quality, pre-treatment process, design and selection of digestion process and process conditions including pH, temperature, carbon to nitrogen (C: N) ratio, organic loading rate and hydraulic retention time. The review reveals that solid-state anaerobic digestion (SSAD) is best suited for OFMSW due to its high solid concentration (>15%) and better process performance. The continuous digestion with thermophilic temperatures was found to be the best condition for high solid AD process. The plug flow and continuous stir tank reactors were the best performing options to control the biological conditions for the digestate post-treatment. Proper selection of the parameters for the whole process is crucial in ensuring process feasibility and economic sustainability of AD of OFMSW. The study revealed that the AD of OFMSW could play a significant role to mitigate waste and waste-related problems

A comprehensive defect study of tungsten disulfide (WS2) as electron transport layer in perovskite solar cells by numerical simulation

In this study, an ideal planar perovskite solar cell (PSC) has been proposed and simulated by using Tungsten Disulfide (WS2) as an electron transport layer (ETL). Effects of various amphoteric defect states of PSC based on CH3NH3PbI3−xXx absorber layer and the interface properties of both ETL and hole transport layer (HTL) are quantitatively analysed by SCAPS-1D numerical simulator. Results show that the device performance is highly influenced by amphoteric defects in the absorber layer rather than the interface defects layer (IDL). It is also revealed that the quantitative tolerable range in CH3NH3PbI3−xXx and IDLs are less than 1015 cm−3 and 1016 cm−3, respectively. The PSC exhibits better performance in the range of 10 °C–40 °C and degrades gradually at higher temperature. With the proposed structure, the simulation finds the highest power conversion efficiency (PCE) of PSC to be 25.70% (Voc = 1.056 V, Jsc = 25.483 mA/cm2, and FF = 88.54%). Keywords: Perovskite solar cells, WS2 thin films, Hole transport layers, Electron transport layer, Amphoteric defects, Interface properties, Numerical simulation, SCAPS-1