Evaluation of future food waste management alternatives in Istanbul from the life cycle assessment perspective

In developing countries like Turkey, food waste has the highest share compared to other municipal solid waste components. A detailed life cycle assessment has been performed to evaluate different food waste management options (i.e., landfilling, anaerobic digestion, thermal treatment, co-treatment with municipal wastewater) for Istanbul which is the largest city of Turkey and Europe. The current waste management has the worst environmental performance compared to proposed waste management scenarios as follows: Anaerobic digestion, thermal treatment and co-treatment with municipal wastewater. The thermal treatment scenario has been found to have the best environmental performance in most of the impact categories including climate change. The anaerobic digestion scenario ranks in the first place only in freshwater eutrophication, which is attributed to avoided fertilizer use in this scenario. A drastic improvement with 866% has been found in this category if the anaerobic digestion scenario was followed. Co-treatment with municipal wastewater refers to use of food waste disposers at households and provides improvements especially in marine eutrophication and ecotoxicity. Lower effluent emissions by means of biological wastewater treatment in the co-treatment scenario compared to other proposed scenarios lead to better performance in these categories. Various sub-scenarios have also been investigated such as using biogas as vehicle fuel, replacing a combined heat and power with a condensing plant and increasing food waste addition to sewer lines. Important improvements are not achievable in the first two sub-scenarios; however, increasing food waste addition to sewer lines reduces various environmental impact categories by −41% and −60%.