Abstract:In response to significant organic waste generation, environmental policies are increasingly mandating diversion of organic waste from landfills and promoting alternative management practices to produce energy and reduce greenhouse gas emissions (GHG). Anaerobic digestion and composting are organic waste treatment alternatives, however, both practices require careful management to prevent similar environmental impacts as landfills. A model was developed to assess the impact of anaerobic digestion followed by composting of food waste and green waste mixtures on net energy production, global warming potential and scarce water use. The model included the ability to vary the initial organic waste composition, decomposition kinetics and treatment time. Energy needs for composting aeration and water pumping, and water use decreased as anaerobic digestion time increased. Composting water use savings for an organic waste anaerobically digested for 90 days prior to composting compared to zero days prior to composting ranged between 25%–53% for different organic waste compositions (from 1:0 to 0:1 green waste to food waste ratios), and energy use savings for composting aeration and water pumping ranged between 15%–17% and 24%–54%, respectively, for the same conditions. For an anaerobic digestion pretreatment time of 30 days prior to composting, the analysis predicted scarce water use to be 0.31–1.09 m³ sw_e/Mg waste, primary energy use to be −168.5–298.3 MJ/Mg waste, and global warming potential to be 8.1–26.4 kg CO₂e/Mg waste. The results will help inform the design and maintenance of waste treatment in resource-limited environments.