Deliverable 4.3 Decision support guideline based on LCA and cost/efficiency assessment

The environmental sustainability assessments described in this report is based on life cycle assessments (LCA) of selected waste water treatment technology (WWTT) cases included in NEPTUNE. The basic approach in these assessments (avoided against induced impacts) is described in Deliverable 4.1 (Larsen et al. 2007) and other methodological issues (e.g. normalization and weighting) in Deliverable 4.2 (Larsen et al. 2009).

The basic approach is illustrated in a simplified way for the case ozonation in Figure 2.1. The technologies investigated include conventional WWT (reference), ozonation, sand filtration, PAC addition, anammox, sludge incineration (reference), other sludge inertization technologies (wet oxidation, high temperature pyrolysis, gasification) and sludge triage (including sludge disintegration technologies, i.e. thermal hydrolysis and ultrasound disintegration).

They are divided into four clusters related to the main purpose of the treatment, e.g. nutrient removal or micropollutant removal. All are assessed within the cluster by comparing with the reference or by looking at induced versus avoided environmental impacts potentials originated from the various emissions and flows inventoried.

Figure 2.1 Do we induce more environmental impact than we avoid by introducing a new waste water treatment technology (sub-optimisation)? The study is based as much as possible on data obtained directly from NEPTUNE partners for the physical and functional inventory. In particular, the functional inventory of cluster 1 on micropollutant removal, tracks 22 organic micropollutants (pharmaceuticals) that have been sampled in different WWTTs by NEPTUNE partners.

The resulting inventory is then modelled according to the EDIP97 methodology on the GaBi LCA modelling software, i.e. GaBi 4 (PE 2008), with EcoInvent 2.0 database integrated (EcoInvent 2007).