Recuperación de fósforo en forma de hidroxiapatita a partir del agua residual generada en campus universitarios: caso de estudio Universidad Autónoma de Occidente

Abstract

In this project, the potential for the hydroxyapatite formation from wastewater was evaluated as a strategy for reducing the impacts generated by wastewater discharges on aquatic and terrestrial ecosystems and for the recovery of nutrients from wastewater treatment. The experimental work was carried out using the tributary wastewater (ARC) and effluent (ART) of the Wastewater Treatment Plant of the Universidad Autónoma de Occidente. In defining the tests, a characterization of the ARC and ART was carried out where it was established that the operational conditions to be ensured to promote the formation and precipitation of hydroxyapatite should consider a solubility product (pKso) value between 52.3 and 57.9 in a reaction pH range between 8.7 and 13.7 units for ARC characteristics and a pKso value between 46.9 and 52.2 in a reaction pH range between 8.4 and 11.9 units for ART.

To evaluate nutrient recovery processes, laboratory-scale chemical precipitation tests were performed using a PB-900 Phipps and Bird programmable mixer, with 700 mL jars. For each type of wastewater, 2 types of tests were performed, one reaction pH adjustment and MgCl2 as a precipitation reagent and another with reaction pH adjustment to promote precipitation.

Analysis of wastewater quality in study showed that the amount of potentially recoverable is 51.14 ± 28.92 g per m3 of treated ARC and of 20.36 ± 13.92 g per m3 of treated ART, this considering maximum use of available phosphate in both types of wastewater. The results of the precipitation process performance with both reaction pH adjustment and MgCl2 as precipitation reagent and only with reaction pH adjustment, showed that in terms of particulate matter reduction, reduction efficiencies were presented in intervals between 51,4 and 71,6% and between 64,1 and 100% for ARC tests and between 55,3 and 100% and between 54,6 and 100% for ART tests, respectively, measures such as the reduction in terms of SST