As an increasingly abundant lignocellulosic biomass with high moisture content, spent coffee grounds (SCG) are an ideal feedstock for hydrothermal carbonization (HTC). The few examples that have converted SCG into a solid fuel hydrochar have yet to address the char's prohibitively high nitrogen content (∼3 wt %)−a barrier to commercialization due to NOx emission regulations. In this work, an alkaline pretreatment is presented that reduces the N content prior to carbonization under regimes optimized for maximum calorific value (HHV), energy yield, and a conflation of both fuel properties. Characterization of hydrochars and secondary chars, the extractable volatile phase, revealed the highest calorific value for the secondary chars (max HHV = 40.69 MJ/kg) and a minimum N content of 0.1 wt % in hydrochars derived from the alkali pretreated feedstock. Char thermal stability and oxidative reactivity were also determined, with pretreated primary chars exhibiting superior combustion reactivities, ignition, and burnout temperatures. Management of HTC process water is both an environmental and operational challenge due to the presence of phytotoxic organic components and the energy expenditure associated with heating large volumes of water. To this end, the process water was recirculated for up to five cycles resulting in an increase in HHV, energy, and solid yield as well as compositional change of the char products.

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volume provides a glimpse of diverse European views on major religions in Africa. The essays clearly balance the contributions made by Europeans' participation and traditions in their historical value to situate African religions, something that may interest anthropologists, historians, missiologists, and all those interested in African studies in general.

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