BIOLOGICAL REMOVAL OF PHOSPHORUS FROM WASTEWATERS BY ALTERNATING AEROBIC AND ANAEROBIC CONDITIONS

A new process alternating aerobic and anaerobic conditions has been te sted for continuous removal of phosphorus from wastewaters. Preliminar y batch runs have been carried out at different temperatures (5 divide d by 35 degrees C) to study the effect of stress related to changes of temperature, inoculating a synthetic medium with the biomass from the same plant operating in continuous mode. The continuous system, which appeared capable of ensuring phosphorus removals higher than 90% at r elatively high phosphate levels, is now studied mainly during the tran sitions between aerobic and anaerobic stages. The present results show , for the first time, a direct influence of dissolved oxygen level on pH and allow reasonable hypotheses on the mechanisms for both carbon a nd phosphorus routes.