(105a) Restaurant Food Waste in UAE: Life Cycle Assessment (LCA) and Feasibility of Conversion into Usable Biogas through Anaerobic Digestion

Restaurants contribute 32% of UAE food waste generated annually that ends up mostly in landfills. The associated environmental impacts of food waste landfilling are of concern globally. Consequently, alternative waste management technologies have been considered to replace landfill. This study employs life cycle assessment (LCA) to compare landfilling (BaU) of restaurant food waste with two other scenarios namely, anaerobic digestion (AD) and composting (COMP) to investigate the most environmentally beneficial system. The assessment allocated useful byproducts such as electricity and compost as environmental benefits and assessed how those influence the results.

The results showed that anaerobic digestion (AD) performed better in 5 of 6 impact categories assessed – climate change, freshwater eutrophication, terrestrial human toxicity cancer and non-cancer, and fossil depletion. Composting (COMP) showed a lower environmental impact compared to landfilling in 4 of 6 impact categories. The study found that AD showed a significant net environmental benefit especially in the climate change and fossil depletion categories; −1080 kg CO₂ eq. and −459 oil eq. respectively. The environmental impacts of all the assessed systems are influenced by distance traveled to convey waste to the treatment facilities, thus a strategic siting of anaerobic digestion systems to reduce transportation will further improve its environmental performance as a viable food waste disposal system.

Biogas is the main product from food waste anaerobic digestion, which is a renewable resource that can be used for heating, cocking and electricity production. However, to ensure continuous and feasible production of biogas, restaurant food waste is mixed with cattle manure before being processed by 5 anaerobic digesters in series. Such configuration is expected to treat between 1,500 to 2,200 metric tonnes of restaurant food waste, which is approximately 0.05% of Dubai’s annual food waste based on 2015 figures.

Such AD configuration is expected to produce annually between 0.29 to 0.41 million cubic meters of biogas with expected unit cost of $1.86 – 2.67 per cubic meter. The biogas can be sold directly as cooking gas, or it can be converted into electricity to cover the daily consumption of 130 – 190 persons.

The outcome of the study can be used as a basis by the UAE government to achieve its goal of diverting 75% of municipality solid waste from landfills. Also, the study shows that anaerobic digestion plants integrated with CHP units can be strategically sited across the country to generate clean electricity thereby reducing the environmental impact of transportation. However, further study is required to assess the financial and economic feasibility of suitable AD system for the UAE environment.