Estimation of Attached Growth Process Aeration Requirement in Wastewater Treatment

Abstract

Attached growth process in wastewater treatment is widely used in order to achieve the sufficient biodegradation of organic matter and nutrient removal. Since the biofilm is attached to a carrier in this process, the substrate and oxygen shall be transported to the biomass surface and reach the deeper layer of the biofilm via diffusion. The driving force of the process is the dissolved oxygen (DO) concentration difference, therefore at least 4–5 mg/L DO is required in this system, which is relatively high compared to activated sludge, where the DO is 1.8–2.5 mg/L. In the attached growth systems, where the suspended matter concentration is low, the relative oxygen diffusion rate (α) is about 0.7–0.8, which is an elevated value compared to the activated sludge system, where alpha is 0.4–0.5. The aim of this paper is to estimate the aeration requirement of the wastewater system applying biofilm; the above mentioned two properties are to be taken into account and the results will be compared to the conventional activated sludge system aeration need.