Composting of biodegradable municipal waste in Ireland

Abstract

The implementation of the Landfill Directive (96/31/EC) will lead to a massive reduction in quantities of Biodegradable Municipal Waste (BMW), which may be landfilled. In 2016, an estimated 2.6 million tonnes of BMW will require diversion from landfill in Ireland. Recycling of dry paper, reuse of textiles and home composting will divert significant quantities of BMW. However, to divert the quantities required to comply with the Directive a significant proportion of the Organic Fraction of Municipal Solid Waste (OFMSW) will require treatment in centralised biological facilities. A survey was undertaken of composting facilities in Ireland to ascertain present capacity, present technology employed and types of feedstock composted. A generic model (consisting of in-vessel composting followed by aerated static pile composting) was generated from technical, economic and environmental data obtained from the survey. The generic model is utilized to ascertain the effect of economies of scale, the effect of gate fees on potential profit per tonne feedstock and the greenhouse gas contribution of the composting process. The model was investigated for four scenarios ranging from small (11ktpa) to very large (220ktpa). The economic analysis indicated that a potential for profit of €52.5/t-€65.4/t was achievable without sale of compost. The direct greenhouse gas production equated to 566kgCO2/t. However considering the "do-nothing" scenario of landfill, 1,175kgCO2 equiv/t is avoided. Thus 1 tonne of BMW saves 609kgCO2 equiv.