Mechanical aerators' power and aeration control in bioreactors

Mechanical aerators, used in many industrial plants for wastewater treatmen t, are the largest energy consumers in biological reactors. A number of aer ators of equal or different power may be used with aeration control achieve d by selecting appropriate working aerator combinations, and by changing ae rators' submergence, provided by a control weir lift at the exit of reactor s. Effective control may be implemented by selecting an adequate combinatio n of working aerators and control weir lift for achieving the necessary oxy gen demand. In this paper an approximate method is proposed for determining the characteristics of aerators used for controlling the necessary oxygen supply. The method is based on an experimental determination of power chara cteristics of aerators under field conditions at different water levels in reactors, and on the use of known oxygen transfer rate under normal conditi ons and characteristics of weirs for water level control. Application of th e proposed method has made it possible to obtain a mathematical model, whic h is used for the control of aeration in two biological reactors of Netanya Wastewater Treatment Works (Netanya, Israel).