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Summary The processing of waste through pyrolysis technology is gaining momentum worldwide and is considered to be a green technology to reduce CO2 emissions. This study is devoted to analysing the lignocellulosic biomass (date palm) and wastewater‐derived microalgae and the carbon‐rich char produced between temperature range (400°C‐600°C) from these biomass types. The properties of microalgae char showed that significant variation with date palm char exhibited high heating values (24‐28 MJ/kg), low ash content (11%‐16%), and high energy yield (48%‐42%). Algal biomass char showed considerably high nitrogen content (6%‐7%) as compared with date palm char (<1%), lower stability, and more significant influence on the price with respect to treatment temperature. Quaternary, pyrrolic, and pyridinic nitrogen species were found on the surface of the microalgae char, whereas no nitrogen species detected on date palm char due to low nitrogen content. The activation energy was also noted to be high for algal char during pyrolysis and combustion process. It can be concluded that date palm char is suitable for energy applications, whereas, algal char can be used for soil amendment, wastewater treatment, and applications requiring nitrogen‐doped char.

<p>Microalgae-derived char contains low stability and heating values with relatively high nitrogen content than lignocellulosic char. This study showed that co-pyrolysis helped improve the overall properties of char than individual pyrolysis of these feedstocks. Two batches of experiments were conducted (a) single step pyrolysis and (b) two-step pyrolysis in the range of highest treatment temperature of 400 – 600 °C. Single step pyrolysed char showed, lower aromaticity, higher yield, ash content and heating values of the char than two-step pyrolysed char. Similarly, ignition temperature and activation energy were higher during combustion by single step pyrolysed char than two-step char. Hence, two-step pyrolysed char is suitable in the energy applications, and low-temperature processing (400 – 500 °C) will result in optimum properties in terms of yield and heating values. </p>

The ignition and combustion behavior of biomass and biomass blends under typical heating conditions were investigated. Thermogravimetric analyses were performed on stalk and woody biomass, alone and blended with various additive weight ratios. The combustion process was enhanced by adding oxygen to the primary air. This led to shorter devolatilization/pyrolysis and char burnout stages, which both took place at lower temperatures than in air alone. The results of the ignition study of stalk biomass show a decrease in ignition temperature as the particle size decreases. This indicates homogeneous ignition, where the volatiles burn in the gas phase, preventing oxygen from reaching the particle surface.The behavior of biomass fuels in the burning process was analyzed, and the effects of heat production and additive type were investigated. Mixing with additives is a method for modifying biofuel and obtaining a more continuous heat release process. Differential scanning calorimetric-thermogravimetric (DSC-TGA) analysis revealed that when the additive is added to biomass, the volatilization rate is modified, the heat release is affected, and the combustion residue is reduced at the same final combustion temperature.

Date palm biomass generates a huge amount of waste throughout the world which can be utilized to produce energy through thermochemical or biochemical conversion technologies. The objective of this study is to present a detailed characterization of parts of date palm branches (twig) and analyse the trace elements including heavy metals for environmental safety and potential slagging and fouling in a reactor. The biomass was divided into four parts: L (leaf ribs), SB (small part of the branch attached to the ribs), MB (middle part of the branch), and LB (large part of the branch attached to the trunk). Different characterization techniques applied were X-ray diffraction, Thermogravimetric analysis, FT-IR, Inductively coupled plasma mass spectrometry, X-Ray Fluorescence, Higher heating values, and ultimate (CHNSO) analysis. High crystallinity was observed in LB with all the heavy metals present in permissible limits. However, it showed a considerably high moisture holding capability. Conversely, SB was found to have low moisture holding capability, moderate higher heating values, and one heavy metal (As) higher than the permissible limit defined by the European Union standards. It can be concluded that LB can be used directly for energy generation after sun drying. The other parts are required to be treated for heavy metal reduction before being used for energy production, keeping in mind the environmental safety.