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• An integrated framework for optimizing waste valorisation methods is developed. • Three technologies are evaluated: pyrolysis, liquefaction and gasification. • The framework considers technical, economic and environmental factors. • The model supports stakeholders' decision-making on waste management strategies. Waste is the most abundant biomass worldwide for renewable energy and value-added products generation. While technologies for the treatment of multiple waste categories continue to evolve, frameworks that facilitate strategic decision-making within bio-economies are required. Therefore, the aim of this research is to develop a framework that can identify optimal processing route for converting different biomass wastes into valuable products. This study considers five different waste types available in Qatar, including date seed, camel manure, municipal solid waste (MSW), food waste, and sewage sludge. Whereas the investigated technologies include pyrolysis, gasification, and hydrothermal liquefaction (HTL). The three processes were simulated in Aspen Plus® and evaluated in terms of their technical, environmental, and economic performance for the different selected biomass feedstocks. A two-stage optimisation framework was then developed to identify the optimal processing technology for each biomass considering multiple products generation (i.e., syngas, biochar, and bio-oil). Investigating the waste to energy pathways, the presented model maximised net profit and energy generation while minimised the total associated emissions. The model indicated that gasification is the optimal processing technology to achieve higher economic return. While pyrolysis is recommended for the achievement of highest energy return. Nevertheless, HTL exhibited the best environmental performance with the lowest associated emissions. In addition, various wastes such as MSW and food waste are best processed by gasification to fulfil the environmental and economic criteria, while pyrolysis is more energy efficient in processing these wastes. Whereas HTL has been recommended only for high moisture containing biomass like manure and sludge, demonstrating relatively high energy efficiency, but lower economic return relative to gasification and pyrolysis. The presented optimisation framework may provide insights for decision-makers to optimally valorise waste considering national priorities. [ABSTRACT FROM AUTHOR]

In this study, a representation of the Energy-Water-Food (EWF) nexus is developed to capture the trade-offs and synergies between sustainability dimensions within an industrial park. A unique systems approach based on thermodynamics is developed to optimise the nexus and enhance resource efficiency. The case study involves various chemical processes operating in the State of Qatar, which is evaluated to ascertain resource efficiency enhancement possibilities across various scenarios, and considers multiple objectives to capture the trade-offs between minimising the total annual cost and environmental emissions. Furthermore, a sustainability metric is applied to compute the effect of each scenario on EWF resources. In this study, there is emphasis on capturing the synergetic potential from utilising biomass from the food sector. The results indicate that the global warming potential in the best performing scenario decreases by approximately 30 %, while the exergy efficiency of the system is enhanced by 28 %. [ABSTRACT FROM AUTHOR]

The agricultural industry in Qatar is highly dependent on using soil enhancing materials due to challenging soil and climatic conditions. Hence, this work investigated the potential of industrial biosludge from the wastewater treatment plant (WWTP) of a Gas-to-Liquids (GTL) plant to enhance an arid soil compared to fertilizer and compost. A fodder crop, buffel grass (Cenchrus ciliaris), was grown in semi-controlled pots containing a typical Qatari agricultural soil and admixtures over a 12-month period. The treatments included soil plus five biosludge percentage contents: 0.75, 1.5, 3, 6 and 12%. These were compared with soil only, soil plus 20-20-20 NPK fertilizer and soil plus 3% compost controls. Analyses of soil physical and chemical properties, the resulting leachate, and plant growth characteristics were conducted at set periods. The results indicate that up to 3% biosludge content led to better plant growth compared to the controls, with the optimum at 1.5% biosludge content for all growth characteristics studied. Biosludge addition to soil increased the volume of different pore types, especially micropores, which enhanced water retention and influenced plant growth. Regression modelling identified leachate Si and Fe concentrations, and biomass K content as the most influential variables for fresh biomass weight, plant height and the number of tillers, respectively. Biosludge addition to the soil around the optimum level did not cause detrimental changes to the resulting leachate and plant biomass. The findings of this work could lead to minimization of biosludge landfilling and allow for savings in fertilizers and irrigation water in arid regions. Image 1 • Biosludge from wastewater of a gas-to-liquids plant improved arid soil behavior. • Up to 3% biosludge content caused better grass growth than fertilizer and compost. • The optimum level for all growth characteristics studied was 1.5% biosludge content. • Biosludge addition increased micropores volume and enhanced soil water retention. • The findings support waste utilization and fertilizer and irrigation water savings. [ABSTRACT FROM AUTHOR]