ABSTRACT
Struvite recovered from anaerobically digested sludge can be conducted by a two – step process. The first step consists of electrodialytic extraction of phosphorus and heavy metals from the waste. The second step comprises the chemical precipitation of phosphorus as struvite. This work studied if the quality of phosphorus recovered as struvite is affected by the reduction of energy on the electrodialytic extraction step. Four electrodialytic experiments were carried out to assess the effect of the energy reduction through stirring time. This was followed by four struvite-precipitation experiments. The efficacy of the electrodialytic extraction of heavy metals is not affected by reducing the stirring from continuous mode to just 25% of the time. XRD analysis confirmed that the precipitates were constituted by pure struvite, while no significant accumulation of heavy metals was found in produced struvite. The struvite meets the requirements for use as phosphorus-based fertiliser.
