An environmental assessment of electricity production from slaughterhouse residues. Linking urban, industrial and waste management systems

The food processing industry continues to grow, generating large amount of organically rich waste flows per year: these processors face significant economic and environmental pressures for appropriate conversion and disposal of these waste flows. Solid waste disposal problems, mostly in highly urbanized environments, energy shortages (primarily oil) and/or high petroleum prices, as well as environmental issues such as the shrinking landfill capacity, can all be addressed by converting waste material into useful and saleable products. This paper brings to the attention a possible strategy in order to meet the general EU directives concerning the residues utilization and percentage contribution for the total energy consumption by 2020, by evaluating the use of animal by-products (category 3, as defined in the directive 2002/1774/EC) for energy purposes. Slaughterhouse waste represents an important potential source of renewable energy: on average, 40-50% of a live animal is waste, with a potential energy content close to diesel fuel. Treatment of animal waste from slaughterhouse and the subsequent conversion to electricity is investigated as a case study in the Campania Region (Italy): the animal waste undergoes a rendering process, to separate a protein-rich fraction useful for animal meal production and a fat-rich fraction, to be combusted in a diesel engine for power and heat generation (CHP). An environmental assessment of the entire process is performed by means of LCA, providing a quantitative understanding of the plant processing. The study aims to understand to what extent electricity production from animal fat is environmentally sound and if there are steps and/or components that require further attention. The environmental impacts of the electricity production from animal waste are investigated adopting different points of view and they are also compared to the impacts of Italian electricity production (mix of fossil fuels and renewables). The study confirms that waste recovery represents a triple win solution, dealing simultaneously with human security, pollution, and, last but not least, energy recovery. (C) 2016 Elsevier Ltd. All rights reserved.