Air Diffusion In Biological Wastewater Reactor: Blocking Phenomena And Aeration Performances

The behavior of different commercial types of polymeric membranes in real activated sludge reactors for urban wastewaters was studied. Accelerated tests were carried out to evaluate the effect of the on/off switching in the elastomeric diffusers used for the aeration in the biological processes for urban wastewater. The pressure trends incremented ranging from 2% to 18% at different flow rates (2, 3.5 and 6 m3/h/diff). The main mechanism of this increase was related to the fouling of the internal channels of the pores. The pores were characterized by significant change of their geometry comparing with their initial shapes by increasing the crystallization phenomena mainly of Calcium and Iron compounds. Final chemical cleaning was carried out testifying the reversibility of the fouling phenomena with the main removal effect on the formed carbonates. Any changes in terms of oxygen transfer parameters were found. However, reduction of standard aeration efficiency (SAE kgO2/kW) was highilithed with impact in terms of global carbon footprint.