Post-Removal of Phosphorus from Biologically Treated Wastewater and Recovering It as Fertilizer. A Pilot-Scale Attempt—The Project PhoReSe

Abstract

The major issue of raw materials depletion and more specifically of phosphorous (an important fertilizer) has currently become an emergent aspect, due to expected depletion problems, needing immediate handling. This was the reason for the implementation of PhoReSe project that aimed to remove and recover phosphorus from the secondary (biologically treated) effluent of a municipal wastewater treatment plant (WWTP “AINEIA”, located near Thessaloniki, N. Greece), treating the wastewaters of the nearby touristic area. Regarding the phosphorous supplementary removal and recovery treatment options, two methods mainly examined, initially in laboratory scale (batch experiments), i.e. (1) the adsorption of phosphorous, and (2) the chemical precipitation of phosphorus. Both methods further applied in pilot-scale, by performing initially the adsorption of phosphorous onto the AquAsZero commercial sorbent, which is a mixed manganese iron oxy-hydroxide, followed by the chemical precipitation of phosphorous, implemented after the de-sorption process of previously saturated adsorbent. The final precipitate of this procedure examined as an alternative/supplementary fertilizer, returning with this way phosphorus into the natural cycle. These experiments, as applied successfully in pilot-scale, set the basis for the larger-scale relevant application for similar WWTP facilities.