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In this study, the production of activated biochar capsules from sawdust for multipurpose medicinal use was investigated as a value addition strategy. The sawdust was chemically activated using phosphoric acid at a temperature of 450 °C in the absence of oxygen to give a 52.2% of activated biochar from the sawdust. The activated biochar’s ash content was 4.0%, moisture content 2.0% and the iodine number 431 mg/g. A process was designed for the production of activated biochar capsules for multipurpose medicinal use. An environmental analysis was done taking for proper site selection and plant layout. An economic analysis carried out indicated a return on investment of 44% and a payback period of 2.3 years. Saw dust can be economically value added to activated biochar capsules as a waste management initiative. [ABSTRACT FROM AUTHOR]

Huge amounts of municipal sewage sludge, a form of solid waste, are being generated daily from municipal sewage treatment plants. This sewage sludge if not properly treated can cause landfilling problems that can result in climate change effects due to greenhouse gases emissions. This generated sewage sludge is rich in phosphorous and other nutrients which has potential to be recovered. The current study evaluates the potential to recover phosphorous from municipal sewage sludge using gasification as a thermal method followed by alkali treatment using NaOH. The sewage sludge was first dewatered to 60% moisture content before it was gasified using hot air to convert it into ash for 120 minutes. Gasification at 800 °C was considered as the waste management option for the sewage sludge due to its flexibility and energy efficiency. In this study, 50% of the phosphate was recovered from the sewage sludge ash with a phosphorous nutrient composition of 6.5-7.5 wt. %. Gasification of sewage sludge to recover phosphate oxide and its subsequent alkali treatment to recover phosphate promotes environmental preservation at the same time creating a resource for fertilizer production. [ABSTRACT FROM AUTHOR]

The brewery industry generates a lot of bio waste with potential for valorisation to bio energy. This study evaluated the possibility to produce environmentally friendly bio coal pellets from brewers spent grains through hydrothermal carbonisation technology. The bio coal pellets had a heating value of 26.1 MJ/Kg and a fixed carbon of 53.1% which were both higher than fossil coal. The bio coal also had a moisture content of 3.8%, ash content of 21.6% and volatile matter of 21.5%. The process designed had an energy integration system to use heat from the waste gases to reduce production costs. The total capital investment was USD 7.6 million, with the bio coal pellets production costs of USD 190.60 per tonne and a selling price of USD 200.00. The net present value was positive with a 21.7% return on investment and a payback period of 4.6 years. [ABSTRACT FROM AUTHOR]

Bauxite Metallurgical Residue (BR) is a highly alkaline and very fine-grained by-product of the Bayer process for alumina production. Its huge global annual production has resulted in increasing accumulation of BR, causing deposition problems and serious environmental issues. RM contains oxides and salts of the main elements Fe, Al, Ca, Na, Si, Ti, and rare earths—REEs (Sc, Nd, Y, La, Ce, Ds)—many of which have been categorised by EU as critical metals (CMs). The valorisation of BR as a low-cost secondary raw material and metal resource could be a route for its reduction, introducing the waste into the economic cycle. REEScue constitutes a research project that aims to instigate the efficient exploitation of European bauxite residues, resulting from alumina production from Greece (MYTILINEOS SA), Turkey (ETI Aluminium), and Romania (ALUM SA), containing appreciable concentrations of scandium and REEs, through the development of a number of innovative extraction and separation technologies that can efficiently address the drawbacks of the existing solution. The consortium consists of three alumina producers from Greece (MYTILINEOS SA), Turkey (ETI Aluminium), and Romania (ALUM SA) and two academic partners from Greece (National Technical University of Athens) and Turkey (Necmettin Erbacan University). We present preliminary characterization results of three different BR samples that originate from the three aluminium industries, in respect of bulk chemical analysis (XRF, ICP), mineralogical investigation (XRD), and morphological observation through microscopy. [ABSTRACT FROM AUTHOR]

Electrolysis experiments to produce Al-Sc alloys were carried out in galvanostatic mode using a cryolitic melt with a NaF/AlF3 molar ratio of 2.2 at 980 °C, using both synthetic and waste feeds. After elucidation of the cryolite electrolyte bath chemistry when adding Sc2O3, small-laboratory scale trials allowed for the demonstration of the process and the study and for the optimisation of the electrolysis parameters. Experiments in large-scale electrolysis cells allowed us to run long-term trials in continuous operation, while the on-line monitoring of the cell off-gases ensured the environmentally benign performance of the process. The aluminium product obtained contained 0.6–2.6 wt% Sc, depending on the current density applied. The material is suited to prepare Al-Sc master alloys for 3D printing powders. [ABSTRACT FROM AUTHOR]

Climate change remains a major topic of global concern in the twenty-first century. Recent research in this area has been focused on managing its impact and halting the increase of anthropogenic atmospheric greenhouse gases (GHGs). The construction and waste management industries remain one of the important players in the production of GHGs. Research works involving the calcination of eggshells has often been done by burning both shell and its constituent proteins and membrane. In the pursuit of a circular economy, this research investigated the effect of membrane separation on the calcination process and quality of CaO produced. Acetic and nitric acid was used to leach the eggshells and aid separation of the shell membrane. XRD, XRF, AA, and RGB analysis were used to characterize the calcined shells and leachate. Leaching was optimum at 60 minutes and averaged at 17 minutes. Optimum calcination occurred at 900°c. Leached and separated shells produced higher calcium concentration and crystallinity after calcination. Leaching duration beyond 17 minutes did not affect calcium content of the calcined shells as seen in the XRF results, however, XRD peaks of CaO experienced a reduction after 17 minutes of leaching. AA analysis also indicates that nitric acid dissolved more Ca during leaching. [ABSTRACT FROM AUTHOR]

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