Closed-loop control of ammonium concentration in nitritation: Convenient for reactor operation but also for modeling

Efficient and automated start-up of a pilot reactor for nitritation of reject water: From batch granulation to high rate continuous operation

“…Figure 3). This control strategy is feasible due to the on-line measurement of ammonium concentration in the bulk liquid, confirming the convenience of this measurement for the high performance of nitritation in this type of reactors, as recently highlighted in the literature [26]. Quantification of NOB fraction in the sludge at day 85 yielded a percentage <1%(0.8±0.3%), whereas the AOB fraction was 53±9%, demonstrating the efficiency of the control strategy to prevent NOB development in the sludge.…”

“…Granulation of conventional activated sludge in SBR is linked to the selection pressure applied when operating at short settling time as already discussed in the introduction. Nevertheless, in the case of autotrophic granular sludge (like for instance, nitrifying granules) the formed granules are very stable [12,15,[26][27][28][29]. The main characteristics of the granular sludge obtained with the batch start-up (as presented in Table 1) remained rather steady, as expected, once the continuous mode of operation was imposed.…”

Effects of the residual ammonium concentration on NOB repression during partial nitritation with granular sludge

“…The change in the bulk ammonium concentrations impacts the nitrate concentration 271 immediately, in a period of hours. This fast response is a clear indication that the residual 272 ammonium concentration can be used as controlled variable for nitritation as pointed out 273 previously (Jemaat et al, 2013). 274…”

A novel control strategy for enhancing biological N-removal in a granular sequencing batch reactor: A model-based study

“…Total biofilm area was defined as a function of granule size and number of granules (see Jemaat et al [34] for further details). The granule size used as model input was the volume-weighted average diameter experimentally determined in the lab-reactor.…”

“…The secondary control loop (Fig. 9) was assumed to have a fast response because the control of DO in the model was described with a high gas-liquid oxygen transfer rate (see the details in SI and Jemaat et al [34]). Before applying the control strategy, the model was run until steady state with a DO concentration of 4 mg O 2 L -1 , obtaining complete nitrification at the end of the cycle and 48% of N-removal efficiency (see Fig.…”