| Abstract
| - Life cycle assessment (LCA) methodology was used tocompare the environmental loads from wastewater systemswith different technical solutions. This study comparedproposed conventional wastewater systems, both large andsmall scale, with separation systems: one in whichurine is handled separately and one in which black wateris treated in a liquid composting process. The studyshowed that large economies of scale, in environmentalterms, could be gained both for the operation and for theconstruction phase. The separation systems outperformedthe conventional systems by showing lower emissions towater and more efficient recycling of nutrients to agriculture,especially of nitrogen but also of phosphorus. Thisimplies that the use of separation systems could significantlyreduce the need for, and hence the production of,mineral fertilizers and thus reduce the overall use ofenergy and phosphate minerals. The combination of large-scale wastewater treatment and urine separation wasfound to be especially advantageous in these respects. Itis concluded that some of the most important environmentaladvantages of separation systems emerge only when modelsof wastewater systems are expanded to also includepotential effects on the production of fertilizers.
|
