Postaeration of Wastewater

Abstract

Recommendations for the design of pneumatic and mechanical aerators and weirs for postaeration are presented. The recommendations are based on experimental results from pilot plant scale and full scale installations. Recommended alternatives are either a series of baffled reservoirs for pneumatic or mechanical aeration or a series of tooth-shaped weirs or openings. Baffling results in a reduction of both required vessel volume and energy consumed. Recommended design parameters for aeration systems are different than those usually accepted for the activated sludge process, for example, intensities of pneumatic aeration as high as 50 to 100 m³/m²/hr, with aerators covering up to 50% to 100% of the tank bottom. Tooth-shaped weirs or openings produce the largest increase in aeration of all the configurations examined, owing to the high degree of nappe conversion.