Long-term evaluation of a sequential batch reactor (SBR) treating dairy wastewater for carbon removal

Abstract

Many dairy industries have been using SBR wastewater treatment plants because they allow optimal working condition to be reached. However, to take advantage of SBR capabilities, strong process automation is needed. The aim of this work is to study the factors that influence SBR performance to improve modelling and control. To better understand the whole process we studied the kinetic modelling, the carbon removal mechanism and the relation between reactor performance, aerobic heterotrophic activity and bacterial population dynamics (by terminal restriction fragment length polymorphisms of 16S rDNA, T-RFLP). The heterotrophic activity values presented high variability during some periods; however, this was not reflected on the reactor performance. As sludge health indicator, the average activity in a period was better than individual values. Although all the carbon removal mechanisms are still unclear for this process, they seemed to be influenced by non-respirometric ways (storage, biosorption, accumulation, etc.). The variability of heterotrophic activity could be correlated with the bacterial population diversity over time. Despite the high variability of the activity, a simple kinetic model (pseudo ASM1) based on apparent constant parameters was developed and calibrated. Such modellisation provided a good tool for control purposes.

The treatment of cheese whey wastewater by sequential anaerobic and aerobic steps in a single digester at pilot scale

“…This population shift was possibly related to the faster growing rate of the acidogens and the fast-acidifying properties of the whey wastewater potentially generating high concentrations of VFA and inhibiting or at least destabilizing the process. While the specific activity on oxygen was, as expected, lower than reported by Gutiérrez et al (2006) for an aerobic SBR (100-400 mgO 2 g VSS À1 d À1 ), it is interesting to note that their calculated specific activity (3400-6900 mgCOD g VSS À1 d À1 ) was not significantly different from the acidogenic activity of our sequential SBR.…”

Molecular Methods in Biological Systems

“…The older system operating at a caravan park had a more diverse community than the newer system at a domestic residence, although bacteria associated with nutrient removal were found at both. In order to model a sequencing batch reactor treating dairy wastewater for process control purposes, the population diversity was determined using T-RFLP and correlated model was calibrated with these findings and kinetic data (Gutierrez et al, 2007). In order to identify aerobic and anaerobic organisms from bioreactors treating different wastewaters, fatty acid methyl esters (FAME) were used as biomarkers.…”