E-Andrew Sindt Creative Component S11.pdf

Perecent deviation (predicted - observed)604020TNNO3-NTPNH3-N0-20-40-60-80-100-120-80 -60 -40 -20 0 20 40 60 80Percent adjustment of OHO yieldFigure 4.5 - Percent error plot for OHO yield for regular mode (0% represents default OHO yield value)4.2.1.2 Maximum Specific Growth Rate DiscussionThe maximum specific bacterial growth rate is defined as the grams of new cells generated per gram ofcells per day. Ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) maximum specificgrowth rates have a direct effect on a system’s capacity for nitrification (BioWin user manual). For theIAWPRC ASM1 model, nitrification maximum specific growth rate kinetic coefficient values can varywidely and are directly related to aeration tank volume requirements and SRT (Tchobanoglous et al.,2003). Rate coefficients have been reported in the range of 0.20-0.90 g VSS/g VSS/d (Tchobanoglous etal., 2003).Barker and Dold (1997) found marked variations in the maximum specific growth rate of nitrifiersbetween systems treating different wastewaters. The quantity of industrial input to the wastewaterappears to correlate with the extent of variation observed. This leads to the suggestion that increasedindustrial inputs can lead to an increased risk of nitrification organism inhibition (Barker and Dold,1997).The industrial input in Grundy Center may cause a change in the maximum specific growth rate of AOBand NOB. The flows and loadings of the industry appear to be highly variable, which at a smaller sizedplant, could have significant impacts to the kinetics of the activated sludge microorganisms.4.2.1.3 Ammonia Oxidizing Bacteria (AOB) Maximum Specific Growth RateThe AOB maximum specific growth rate results are shown in Figure 4.6. It appears that increasing AOBmax specific growth rate has much less influence on effluent parameters than decreasing its value. Themodel was run at 13 day SRT. At 13 day SRT, the default AOB maximum specific growth rate is adequate46