Environmental burdens of source-selected biowaste treatments : comparing scenarios to fulfil the European Union landfill directive. The case of Catalonia

The Organic Fraction of Municipal Solid Waste (OFMSW), or biowaste, can be valorized using different treatment technologies, such as anaerobic digestion and composting or the combination of them. The use of the end products (biogas and/or compost) generates benefits over the alternative of sending waste to landfill. The European Union regulations (i.e. Landfill Directive) encourage the diversion of untreated biodegradable waste from landfilling. However, OFMSW treatment installations also produce environmental impacts that must be assessed. This paper presents different future scenarios at regional scale proposed to accomplish the Landfill Directive and their environmental assessment in terms of environmental impact categories. The geographical area under study is Catalonia (Spain). Field data obtained in previous studies undertaken in the same geographical area are used to determine the environmental burdens of the present situation in order to compare them with different future scenarios. A combined scenario to treat 921 Gg of OFMSW source selected including the increase of the quantity of biowaste treated by anaerobic digestion (61.2% of the total biowaste), the modification of composting plants to ensure the treatment of all the gaseous emissions (25.3% and 8.1% of the total biowaste treated in in-vessel composting plants and in enclosed windrows composting plants respectively) and the incorporation of home composting as a waste treatment alternative (5.4% of total biowaste) results in the lowest impact scenario considered in the present study. Energy recovery through anaerobic digestion and benefits of gaseous emissions reduction are the key factors in the impact reduction of biowaste treatment