Kinetic parameters and inhibition response of ammonia‐ and nitrite‐oxidizing bacteria in membrane bioreactors and conventional activated sludge processes

Abstract

Ammonium and nitrite oxidizing biomasses (AOB and NOB) were investigated in parallel pilot plants: a membrane bioreactor (MBR) and a conventional activated sludge process (CASP) fed with domestic wastewater. The kinetics of AOB and NOB were monitored through titrimetric tests. The maximum specific growth rate of the AOB (micro(max,AOB)) was affected by the solids' retention time (SRT) maintained during the start up: by varying the start up SRT from 20 d to 8 d, micro(max,AOB) in the CASP varied from 0.45 d(-1) +/- 0.04 to 0.72 d(-1) +/- 0.2 respectively; the mean value of micro(max,AOB) in the MBR samples (always maintained at SRT = 20 d) was in the range 0.45-0.49 d(-1). The endogenous decay coefficients of the NOB and AOB and the maximum specific growth rates of the NOB were similar in both MBR and CASP. Inhibition tests with different concentrations of allylthiourea (ATU) were carried out on samples from both activated sludge systems: the MBR sludge exhibited higher sensitivity to a low ATU concentration; however, the maximum nitrification activity recovered more rapidly than the CASP sludge.

Fast start-up and controlled operation during a long-term period of a high-rate partial nitrification activated sludge system

“…On the other hand, the average specific nitrifying capacity in this study (1.5 ± 0.3 g N g −1 VSS d −1 at SRT = 8 d) was clearly higher than the one obtained by Jubany et al [7] (0.7 ± 0.2 g N g −1 VSS d −1 at SRT = 30 d). This result agrees with those studies reporting an increase of the specific nitrifying capacity with a decrease of the SRT [18][19][20]. However, the main data for the design of a full-scale system is the treatment capacity or volumetric TAN oxidation rate (in g N L −1 d −1 ), which is a combination of the biomass concentration (in g VSS L −1 ) and its specific nitrifying capacity (in g N g −1 VSS d −1 ).…”

“…Email: juanantonio.baeza@uab.cat (HRT = SRT), as in the SHARON process [17]. Moreover, the lower the SRT, the higher are the specific nitrifying rates [18][19][20]. However, the activated sludge systems working at low SRT have a limited treatment capacity due to the low biomass concentration that can be achieved and it was reported that the SHARON process could be limited by this restriction [21].…”

“…With this system, it was possible to achieve and maintain stable complete nitritation working at high SRT (30 d) with a significant nitrifying biomass concentration (1800 mg VSS L −1 ). However, the nitrification rate was probably limited in that system by the high SRT used [18][19][20]. Moreover, the start-up of ISSN 0959-3330 print/ISSN 1479-487X online that partial nitrification system was carried out using an inoculum with high AOB percentage [7].…”

From the affinity constant to the half-saturation index: Understanding conventional modeling concepts in novel wastewater treatment processes

“…The previous statement can be illustrated simply with the example of half-saturation indices in MBR systems. Some studies have claimed that MBR systems select for bacterial groups with low half-saturation indices (K-strategists) as compared to CAS due to the high solids retention times (and thus low substrate levels) commonly employed in these types of systems (Munz et al, 2010). Other studies have reported these lower half-saturation indices to be due to the fact that floc sizes are smaller in MBR systems than in CAS (Manser et al, 2005).…”

Comparison of vertical-flow constructed wetlands with and without supplementary aeration treating decentralized domestic wastewater

“…The treatment of decentralized domestic wastewater urgently requires measures which not only can meet environmental criteria for downstream discharge but also can satisfy realistic conditions [3]. Conventional wastewater treatment technologies such as activated sludge treatment methods [4][5][6], etc. are complicated and require overwhelming investment in terms of construction, operation and maintenance [7,8].…”