Cost assessment of different routes for phosphorus recovery from wastewater using data from pilot and production plants

Abstract

Phosphorus recovery from wastewater has considerable potential to supplement limited fossil phosphorus reserves. Reliable cost data are essential for investor and policymaker decisions. In this study, investment and operational costs for nine phosphorus (P) recovery processes were calculated from the investor's perspective, taking into account all relevant side effects on the sludge treatment or the wastewater treatment plant. The assessment was based on pilot and full-scale data which were thoroughly consolidated and standardized with technical and cost data from the German wastewater-sludge treatment train to enable direct comparison. The cost influence of precipitation processes on the current wastewater-sludge treatment train ranges from −0.14 (generating profit) to 0.23 EUR per population equivalent (PE) and year, while the cost influence of sludge leaching processes is around 2.50 EUR/(PE y). The cost influence of processes using dry sludge and mono-incineration ash varies between 0.33 and 3.13 EUR/(PE y), depending on existing disposal pathways, mono-incineration, co-incineration or agricultural use of sludge. The specific costs per kg phosphorus recovered (−4 to 10 EUR/kg P) are in general higher than conventional fertilizer production (1.6 EUR/kg P). However, annual costs per PE represent less than 3% of the total costs for wastewater disposal.