A model of extracellular polymeric substances on crystal growth and morphogenesis of struvite: Effects of sodium alginate

Abstract Struvite crystallization has been regarded as a sustainable route to recover phosphorus from wastewaters. In this study, sodium alginate (SA) was chosen as model extracellular polymeric substances (EPS) to investigate its impact on struvite crystallization. The experimental results demonstrate that SA can remarkably influence struvite morphogenesis, resulting from the selective adsorption and binding of SA molecules onto the crystal faces with higher Mg content. SA concentration-dependent experiments show that SA significantly inhibits struvite growth, and the growth inhibition is caused by the adsorption of SA onto struvite surface, thus blocking the active growth sites. We also found that the elevation in Mg/P ratio or initial pH (pHi) can promote struvite growth, thus compensating the adverse effect of SA. Considering that SA is model EPS, our results provide a new insight into the role of EPS on struvite crystallization from wastewater. This will help to improve struvite crystallization technique.