Decarbonization in waste recycling industry using digitalization to promote net-zero emissions and its implications on sustainability.

Digitalization and sustainability have been considered as critical elements in tackling a growing problem of solid waste in the framework of circular economy (CE). Although digitalization can enhance time-efficiency and/or cost-efficiency, their end-results do not always lead to sustainability. So far, the literatures still lack of a holistic view in understanding the development trends and key roles of digitalization in waste recycling industry to benefit stakeholders and to protect the environment. To bridge this knowledge gap, this work systematically investigates how leveraging digitalization in waste recycling industry could address these research questions: (1) What are the key problems of solid waste recycling? (2) How the trends of digitalization in waste management could benefit a CE? (3) How digitalization could strengthen waste recycling industry in a post-pandemic era? While digitalization boosts material flows in a CE, it is evident that utilizing digital solutions to strengthen waste recycling business could reinforce a resource-efficient, low-carbon, and a CE. In the Industry 4.0 era, digitalization can add 15% (about USD 15.7 trillion) to global economy by 2030. As digitalization grows, making the waste sector shift to a CE could save between 30% and 35% of municipalities' waste management budget. With digitalization, a cost reduction of 3.6% and a revenue increase of 4.1% are projected annually. This would contribute to USD 493 billion in an increasing revenue yearly in the next decade. As digitalization enables tasks to be completed shortly with less manpower, this could save USD 421 billion annually for the next decade. With respect to environmental impacts, digitalization in the waste sector could reduce global CO2 emissions by 15% by 2030 through technological solutions. Overall, this work suggests that digitalization in the waste sector contributes net-zero emission to a digital economy, while transitioning to a sustainable world as its social impacts.

Spent coffee ground as renewable energy source: Evaluation of the drying processes.

Spent coffee ground (SCG) is an environmental nuisance material, but, if appropriately processed it can be converted into pellets, and thus, used as an energy source. The moisture content of the final product should be below 10%, to ensure safe storage, and elimination of microorganism growth (particularly moulds). The present study aims to identify the optimal drying process for removing moisture from SCG and to investigate changes to the composition of SCG due to drying, at temperatures around 75 °C, so that the dried SCG to qualify as renewable energy source. Three drying processes were employed for SCG drying (with initial moisture content of about 65%): oven drying, solar drying and open air sun drying, while SCG samples were placed in aluminium trays with thicknesses of 1.25, 2.5 and 4 cm. Based on the experimental results for SCG samples with thickness 2.5 cm, the open air sun drying process required 10 h to reach final moisture content of 37%, while solar drying achieved 10% moisture content in 10 h and oven drying achieved 7% moisture content in 6 h. The solar drying process proved as the most advantageous, due to low energy requirements and adequate quality of dried SCG. Also, experiments indicated that SCG storage at "normal room conditions" resulted to equilibrium moisture content in SCG of 8%, regardless of the initial moisture content. Furthermore, instrumental analyses of the SCG, revealed changes to its composition for a number of chemical groups, such as aldehydes, ketones, phytosterols, alkaloids, lactones, alcohols, phenols, pyrans and furans, among others. It was also identified that the SCG colour was affected due to the drying process.