Effect of Temperature Downshifts on Performance and Microbial Community Structure on Pilot-Scale Sequencing Batch Biofilm Reactors Treating Hypersaline Wastewater

Shihu Liu, Ziyuan Lin, Jiong Zhou, Yongsheng Zhang, Jiale Wang and Jian Zhou
2021 Nature Environment and Pollution Technology  
Low temperature and high salinity can strongly inhibit metabolic activities of the microbial population, resulting in low efficiency of biological wastewater treatment. Using 70 g.L-1 NaCl pickle mustard wastewater as influent, three pilot-scale sequencing batch biofilm reactors (SBBRs), subjected to temperature downshifts and fluctuation ranging from 30 ± 4°C to 10 ± 4°C, were conducted over 200 days. Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR–DGGE) was used to
more » ... E) was used to reveal the microbial community structure succession in reactors. Results showed that when the temperature was 10 ± 4°C, the COD removal efficiencies of SBBRs (1, 2 and 3 kg COD m-3 d-1 organic loading rate), were 91.6% (σ = 0.87), 87.84% (σ = 0.92) and 83.34 % (σ = 0.85), respectively. Compared with the average removal efficiencies when the reactors operated at 30 ± 4°C, the efficiency reductions of 1, 2 and 3 kg COD m-3 d-1 reactors were 4.47%, 4.58% and 4.57%. As the temperature decreased, microbial population diversity did not change remarkably. However, the microbial structure changed significantly, bacteria which had strong adhesion and a wide growth temperature range were competitive. At low temperature, the predominant species were Thalassolituus oleivorans, Halotalea alkalilenta and Kangiella koreensis, which were all related to pollutant-degrading halophilic bacteria.
doi:10.46488/nept.2021.v20i01.039 doaj:11dacdae09144a67a52e76dfc61253f1 fatcat:m36wwipvovbe5eeecmbmwqpb4y