Linkage of microbial kinetics and bacterial community structure of MBR and hybrid MBBR–MBR systems to treat salinity‐amended urban wastewater

Abstract

Three pilot-scale bioreactors were started up and operated under salinity-amended urban wastewater feeding. The bioreactors were configured as membrane bioreactor and two different hybrid, moving bed biofilm reactor-membrane bioreactor and operated with a hydraulic retention time of 9.5 h, a solid residence time of 11.75 days and a total solids concentration of 2500 mg L . The three systems showed excellent performance in suspended solids, BOD , and COD removal (values of 96-100%, 97-99%, and 88-90%, respectively), but poor nitrogen removal (values of 20-30%). The bacterial community structure during the start-up phase and the stabilization phase were different, as showed by β-diversity analyses. The differences between aerobic and anoxic biomass-and between suspended and attached biomass-were higher at the start-up phase than at the stabilization phase. The start-up phase showed high abundances of Chiayiivirga (mean values around 3-12% relative abundance) and Luteimonas (5-8%), but in the stabilization phase, the domination belonged to Thermomonas (3-14%), Nitrobacter (3-7%), Ottowia (3-11.5%), and Comamonas (2-6%), among others. Multivariate redundancy analyses showed that Thermomonas and Nitrosomonas were positively correlated with fast autotrophic kinetics, while Caulobacter and Ottowia were positively correlated with fast heterotrophic kinetics. Nitrobacter, Rhodanobacter, and Comamonas were positively correlated with fast autotrophic and heterotrophic kinetics. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1483-1495, 2017.

Biofouling Formation and Bacterial Community Structure in Hybrid Moving Bed Biofilm Reactor-Membrane Bioreactors: Influence of Salinity Concentration

“…The absence of attached biofilm in the bioreactors showed that microbial communities in the bioprocesses could not form biofilms over the carrier surface in the presence of constant and variable 3.6 g L −1 NaCl maximum salinity. This result has been observed previously in hybrid MBBR-MBR systems [7] by proposing that salinity inhibits the ability of microorganisms in urban wastewater for the formation of attached biofilms. In practice, the hybrid MBBR-MBR systems operated under both scenarios of salinity operated as MBR systems.…”

“…Additionally, a recycling flow was imposed from the membrane tank to the first chamber. This configuration has been called a hybrid MBBR-MBRn/anox [6,7,20].…”

“…Furthermore, different physico-chemical parameters were measured in the influent wastewater and the effluent of the MBBR-MBR system such as the five-day biochemical oxygen demand (BOD 5 ) and chemical oxygen demand (COD), according to the standard protocols and inorganic nitrogenous ions ammonium, nitrite, and nitrate through ionic chromatography analysis [6,7].…”

“…For the constant salinity scenario, the removal rates of BOD 5 and COD were 98.09% and 88.55% for influent concentrations of 408.33 ± 46.18 mg-BOD 5 L −1 and 654.07 ± 154.57 mg-COD L −1 , respectively. In the case of total nitrogen removal, the influent mean value of 181.14 ± 28.59 mg-N L −1 yielded a 22.97% removal rate [6,7]. For both salinity conditions, the attached biofilm over the carrier media had small concentrations (< 20 mg L −1 and < 40 mg L −1 for the constant and variable salinity scenarios, respectively) with respect to the biomass concentrations in the MLSS (around 2500 mg L −1 ).…”

“…Salinity has been reported to affect microbial activity due to their impact in the bacterial cell mortality increase, in the increase in transmembrane osmotic pressure, and in the inhibition of different metabolic pathways [6]. The effect of salinity over the membrane bioreactor (MBR) and MBBR-MBR systems has been evaluated and is still being investigated in order to fully understand its role in the functioning of these systems and to develop tools to mitigate its impact and increase the performance of salinity wastewater treatment systems [7].…”