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

A new process alternating aerobic and anaerobic conditions has been tested for continuous removal of phosphorus from wastewaters. Preliminary batch runs have been carried out at different temperatures (5 divided 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 relatively high phosphate levels, is now studied mainly during the transitions 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 and phosphorus routes.