An online method for estimation of degradable substrate and biomass in an aerated activated sludge process
Journal article, 2011

The activated sludge process for degradation of organic matter is one of the main processes commonly used in biological wastewater treatment, and aeration in that process stands for a large part of the energy consumed in a plant. Hence, there have been many attempts to improve the operation of the activated sludge process using mathematical models of the process. The advanced models used has in general their origin in IWA (former IAWQ) activated sludge model no 1 (ASM1). Unfortunately, optimization w.r.t. discharge and economy is limited for municipal wastewater treatment plants because several of the most important variables; heterotrophic biomass, readily biodegradable soluble substrate, and slowly biodegradable substrate cannot be reliably measured online because of their complexity hiding behind their notation. With the predenitrifying WWTP in Göteborg having post nitrification in trickling filters as an example, we resolve this problem by deriving an observer that estimates these concentrations in the aerobic parts based on only the commonly available online measurements of oxygen, water flows, TSS concentration and supplied air. Based on control theory analysis and simulations it is concluded that estimation does not work for an activated sludge process with aeration in one stirred tank alone, but when the activated sludge process can be described by at least two tanks in series, with oxygen measurements in each tank, the estimates converge. A sensitivity analysis with respect to deviations in model parameters reveals that the derived estimator is also fairly robust to model errors.

Observer

Soft sensor

Extended Kalman filter

Activated sludge control

Author

Marcus Hedegärd

Chalmers, Signals and Systems, Systems and control

Torsten Wik

Chalmers, Signals and Systems, Systems and control

Water Research

0043-1354 (ISSN) 1879-2448 (eISSN)

Vol. 45 19 6308-6320

Driving Forces

Sustainable development

Areas of Advance

Building Futures (2010-2018)

Subject Categories

Industrial Biotechnology

Other Engineering and Technologies not elsewhere specified

Other Biological Topics

Oceanography, Hydrology, Water Resources

DOI

10.1016/j.watres.2011.09.003

PubMed

22001822

More information

Created

10/8/2017