A kinetic modeling for carbon metabolism in sequencing batch reactor under multiple aerobic/anoxic conditions

Abstract

In order to further investigate activated sludge system for better carbon metabolism and nitrogen removal with less energy consumption, a new kinetic model was established. The detailed description of the proposed model was introduced for understanding the mechanisms involved in the activated sludge system, especially simultaneous substrate storage and biomass growth (SSSG) processes and soluble microbial product generation. The evaluation of the proposed model was demonstrated by a lab-scale sequencing batch reactor (SBR) operated with three different sets, i.e., aeration/non-aeration (set 1), non-aeration/aeration/non-aeration (set 2), and alternating aeration/non-aeration (set 3) processes. The purpose was to investigate carbon metabolism under multiple aerobic/anoxic conditions. The calibrated results showed quite an acceptable model fit to the on-line measured dissolved oxygen (DO) data for the three SBR sets. Predictions of the calibrated model were successfully confirmed using off-line analyses of soluble chemical oxygen demands (COD) and nitrogen dynamic variations, respectively. The simulated results showed that more SMP was generated under aerobic condition than that under anoxic condition, and more nitrate (S (NO)) consumption resulted in less SMP generation, i.e., approximately 7% and 57% less extra carbon source in sets 2 and 3 were required to remove 8% and 58% of S (NO), respectively, compared with set 1. And the kinetics of SSSG process in the proposed model was indirectly validated by comparisons between experimental DO profiles and simulations. Therefore, the new model provides an effective technique for better optimizing the effluent COD and nitrogen with low energy cost in biological wastewater treatment plants.

Modeling microbial growth and dynamics

“…This trade-off has recently been considered in several models (Fan et al 2012;Insel et al 2012;Tamis et al 2014). The model by Fan et al (2012) also incorporated specifically the production of soluble microbial products (SMP) which play an important role in wastewater treatment effluent (Barker and Stuckey 1999). Several models considered the effect of protozoan and metazoan predation on microbial biomass in activated sludge (Moussa et al 2005;Ni et al 2010;Ni et al 2011).…”

“…However, even if only one resource is considered, it remains often unclear how it is divided between microbial growth and investment into storage molecules for growth during famine conditions. This trade-off has recently been considered in several models (Fan et al 2012;Insel et al 2012;Tamis et al 2014). The model by Fan et al (2012) also incorporated specifically the production of soluble microbial products (SMP) which play an important role in wastewater treatment effluent (Barker and Stuckey 1999).…”

“…Ideally, the data for comparison consists of direct measurements, as it is the case in some kinetic modeling studies (e.g. Fan et al 2012;Insel et al 2012).…”