Influence of temperature on struvite precipitation by CO2-deagassing method

The present study explores struvite precipitation by degassing method under different temperature (14.5-35 degrees C). It is shown that an increase of temperature does not affect the nucleation kinetics but strongly influences the growth rate and the efficiency of the phosphate removal. This was attributed to the effect of temperature on the struvite solubility and then the reached supersaturation coefficient. It was also shown, by using degassing method, that the determined solubility constant (pK(s)) values of struvite, at 14.5, 20, 25 and 35 degrees C are 13.00, 12.82, 12.63 and 13.20, respectively, are close to those presented in the literature. The results show that temperature influences the kinetics of precipitation. First-order kinetics were found to be sufficient to describe the rate data. The rates decreased with increasing temperature and the apparent rate constants for the reaction were determined. Arrhenius plots yielded a relatively apparent high activation energy E-a = 31.0 kJ.mol(-1). (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim