Odour and Life Cycle Assessment (LCA) in Waste Management: A Local Assessment Proposal

Abstract

Environmental assessment of municipal solid waste management is essential. Life cycle assessment (LCA) is a powerful and widely used method, which implements causal chains (impact pathways) between the studied processes and their environmental impacts. However, in waste management, the method presents some weaknesses. For example, there is no impact category related to odour, whose assessment is nevertheless essential, especially when the organic fraction of waste is concerned. Odour interferes with human welfare and comfort. Sometimes, it can become a nuisance and be described as a “socio-environmental” impact. To integrate the impact of odour in waste management plans, it is necessary to build an odour-impact pathway. The aim of this paper is to present a first attempt to build such an impact pathway up to the so-called midpoint step (i.e. the level of discomfort to human beings). The methodology we developed is based on the cause/effect chain according to the descriptors of the Site Dependent approach. Unlike classical LCA, the classification step is more important and characterization is aimed at computing the characterization factor. The change in this classification step allows for working on the occurrence of odour impacts. To determine impact occurrence, it is necessary to integrate local conditions into odour assessment. This was done using (1) the USEtox model in which local conditions to assess odour impacts are integrated and (2) the framework of a new methodology that takes into account background concentrations. The methodology was implemented in a case study, i.e. by computing atmospheric emission of ethyl benzene during composting (2.93 × 10−2 kg·day−1). The characterization factor for ethyl benzene was equal to 3.02 × 10−3 kg eq. Benzene per kg emitted ethyl benzene. The daily emission of ethyl benzene generated an odour impact equal to 6.6 × 10−5 kg eq. benzene. With that first odour mid-point impact, we paved the way for the construction of a whole odour pathway (going up to end-point impacts or damages). However, several limits were identified such as data availability, the model under use and the use of average daily data which is less relevant than emission peaks. We should also recall that our methodology is not intended for predicting nuisance likely to disturb populations living nearby the facility. Its first objective is to provide an indicator that fits with LCA methodology in order to help local decision-makers to differentiate waste management scenarios based on exhaustive LCA.