Life cycle assessment of prospective sewage sludge treatment paths in Germany
Due to the amendment of the sewage sludge ordinance, both a thermal post-treatment and a phosphorous recovery from sewage sludge will become mandatory for large-scale wastewater treatment plants in Germany. This study analyzed four prospective treatment paths for sewage sludge by means of life cycle assessment. In the realm of a gate-to-cradle approach, environmental impacts were quantified for all compartments of the ReCiPe Midpoint (H) 2016 method.
Alongside the comparative analysis, a hotspot analysis was carried out and mitigation potentials were identified. For all thermochemical post-treatment paths, it was derived that (i) the share of fossil external energy must be kept to a minimum, (ii) primary or secondary measures to control N2O emissions during the incineration and pyrolysis should be implemented and (iii) the technological approach to recover phosphorous must be carefully selected.
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