A New Method for the Design of Sequencing Batch Reactors (SBR) using the Concept of the Hindered Settling Velocity of the Sludge

Abstract

The paper presents a new methodology for the design of sequencing batch reactors. The design uses the concept of the hindered settling velocity of the sludge, helping in the definition of the settling and idle times during the cycle. Other design routines presented in the literature use the sludge volume index (30-minute settlement in the test), and the time for sludge settling in the reactor is based purely on experience, regardless of the sludge concentration during the react phase. The hindered settling velocity is calculated based on coefficients obtained for each one of five possible sludge settleability ranges (very good, good, fair, poor and very poor). The settling coefficients have been obtained through the combination of values presented in 16 references, with data from a large number of operating full-scale activated sludge plants in different countries of the world. The design routine introduced in the paper is simple, practical and conceptually justifiable, and is believed to represent a step in advancement in relation to other ones currently described in classic textbooks.

Keywords:

• Wastewater treatment
• activated sludge
• sequencing batch reactors
• hindered settling velocity