As a promising green technology, microwave heating is highlighted by its high efficiency and low consumption, especially in the fast pyrolysis treatment for e-waste recycling. Electric discharge induced by microwave–metal interaction plays a significant role in the process, and its contribution to heat generation is, however, always hard to define qualitatively through direct experiments. In this simulation, a microwave heating model featuring the pulsed microwave–metal (MW-m) discharge was designed in multi-dimensions, using COMSOL Multiphysics software, to emphatically probe the depth and extent of the hot-spot effect as well as its auxo-action on the pyrolysis process of waste printed circuit boards (WPCBs). The energy loss generated by MW-m discharge was added into the models in the form of a built-in fluctuating heat source, and it is found that at a relatively low microwave energy-to-heat conversion rate (31.5%, 220.5 W), due to the unique thermal effect of microwave–metal discharge, it can achieve an ideal pyrolysis effect. Based on the results, the instantaneous heat by discharge is generated in the similar trend of radiation pulses, and the local temperature of discharge spots can reach more than 2000 K the instant the discharge occurs, shortening the overall pyrolysis from dozens of minutes to around 200 s.

Nitrogen fixation is essential for all forms of life, as nitrogen is required to biosynthesize fundamental building blocks of creatures, plants, and other life forms. As the main method of artificial nitrogen fixation, Haber–Bosch process (ammonia synthesis) has been supporting the agriculture and chemical industries since the 1910s. However, the disadvantages inherent to the Haber–Bosch process, such as high energy consumption and high emissions, cannot be ignored. Therefore, developing a green nitrogen fixation process has always been a research hotspot. Among the various technologies, plasma-assisted nitrogen fixation technology is very promising due to its small scale, mild reaction conditions, and flexible parameters. In the present work, the basic principles of plasma nitrogen fixation technology and its associated research progress are reviewed. The production efficiency of various plasmas is summarized and compared. Eventually, the prospect of nitrogen fixation using low-temperature plasma in the future was proposed.

Coal sludge is a seriously polluted solid waste, and the rational utilization of its resources has long being an undoubtedly important research topic. This paper mainly studies the coal sludge partial preheating characteristic, combustion characteristic and the process of migration and conversion of nitrogen with preheating combustion technology. The experimental results indicate that most of the elements in the coal sludge are released during preheating, and the ratio of the fuel-N converted to the N2, NH3 and HCN are 75.5%, 6.74% and 0.64%, respectively. Compared with the coal sludge, the BET surface area and cumulative pore area of preheated char are increased. The surface of preheated char is loose and porous with many fine particles, while raw coal is dense with larger particles. Meantime, the quantity of carbon defect structure, the active sites and the reactivity of preheated char are all increased. In the whole process, the NOx emission is about 156 mg/m3 (@6% O2), the ratio of fuel-N converted to NOx was 2.98%, and the combustion efficiency is 96.5%. This experiment results will play a vital role in efficient and clean utilization of coal sludge.

Solid state anaerobic digestion (SSAD) of water poor feedstock may be a promising technology for energy recovery. Feedstocks having high solid concentration like lignocellulosic biomass, crop residues, forestry waste and organic fraction of municipal waste may be the appropriate feedstock for its biochemical conversion into energy carries like biomethane through SSAD. Compared to liquid state anaerobic digestion (LSAD), SSAD can handle higher organic loading rates (OLR), requires less water and smaller reactor volume and may have lower energy demand for heating or stirring and higher volumetric methane productivity. Besides these, pathogen inactivation may also be achieved in SSAD of biodegradable waste. Around 60% of recently built AD systems have adopted SSAD technology. However, the process stability of an SSAD system may have several constraints like limited mass transfer, process inhibitors and selection of digester type and should be addressed prior to the implementation of SSAD technology. In this article, a comprehensive overview of the key aspects influencing the performance of SSAD is discussed along with the need for mathematical modelling approaches. Further to this, reactor configuration for SSAD and digestate management requirement and practice for solid-state condition are reviewed for a better insight of SSAD technology

In this study, a series of Na2S- and S0-decorated ZSM-5 adsorbents were prepared and their Hg0 adsorption performance was evaluated. Given that S0 and Na2S were co-doped with the mass ratio of S0 to ZSM-5 fixed to 2:1, Hg0 removal efficiency quadruples compared with raw ZSM-5 and reached ca. 100% at 300 °C. Combined with the characterization results, it could be concluded that chemical properties, instead of physical structures, played an important role in Hg0 removal. Among the various gas components, O2, NO, and SO2 made negligible impacts on Hg0 capture over 2:1-S/ZSM-5 adsorbent surface. After recycling four times, Hg0 removal efficiency of 2:1-S/ZSM-5 adsorbent remained higher than 80%, which was indicative of a certain recyclability. Finally, XPS results illustrated that S0 and S2? on 2:1-S/ZSM-5 surface functioned as the active sites for the transformation of Hg0 to HgS, which facilitated the chemisorption process and consequently led to an improved Hg0 capture performance.