Phosphorus Competition And Recovery From Wastewater Through Vivianite Production By Dissimilatory Metal Reducing Bacteria

As a required nutrient,phosphorus is involved in almost all biochemical reactions.Phosphorus undergoes a one-way flow from minerals to soil to water,which creates a phosphorus crisis as well as aquatic eutrophication.Wastewater treatment plants serve as enormous urban phosphorus resevoirs,how to achieve an efficient resource recovery with simultaneous wastewater treatment is one of key issues.At the same time,iron has become ubiquitous in modern sewage treatment processes.Dissimilatory metal reduction bacterial(DMRB)are widely distributed in nature.DMRB-induced vivianite recovery from wastewater is a promising route to solve these problems synthetically.However,the current research on vivianite based phosphorus recovery is mainly focused on technological optimization,and the mechanism of vivianite formation mediated by DMRB needs further investigation.In this study,we established the mixed bacterial system which inoculated with sewage,sludge and wastewater biomass,respeciately.In sewage directly inoculated groups,Geobacter was the key microorganism for vivianite formation.Phosphorus recovery rate was 31%-50% and vivianite recovery rate was 7%-33%.Geobacter.sulfurreducens inoculated systems were fed with iron-phosphate mineralization,combining with Scanning Electron Microscope(SEM),XRD,optical microscope and kinetics model,phosphorus competition between biomass growth and bioinduced vivianite mineralization was investigated at the batch scale.An optimal Fe/P stoichiometric ratio of 1:1 was observed for Geobacter-inoculated batches.The highest vivianite recovery rate of 48% was obtained in Fe/P=1:1 group,with values 8% and 45% higher than those at the sewage inoculated systems.Moreover,the vivianite growth series proceeded as follows: tiny blue particles,plain pieces,dark blue nodules,and large spherical crystals.In the optimal Geobacter batch,the μ-S curve indicated biomass growth leads to phosphorus utilization over vivianite mineralization,and a mixed order reaction(0 < x < 1)for both vivianite formation and biomass growth.Overall,our findings provide fundamental data for determining the fate of phosphorus during bioinduced vivianite recovery from wastewater,which has broad implications in phosphorus cycling and vivianite mineralization.