Palmeiro-Sanchez, T., Fra-Vazquez, A., Rey-Martinez, N., Campos, J. L., & Mosquera-Corral, A. (2016). Transient concentrations of NaCl affect the PHA accumulation in mixed microbial culture. J. Hazard. Mater., 306, 332–339.
Abstract: The present study explores the feasibility of the accumulation of polyhydroxyalkanoates (PHAs) under the presence of transient concentrations of added sodium chloride, by means of a mixed microbial culture (MMC). This culture was enriched on a mixture of volatile fatty acids (VFAs) containing 0.8 g Na+/L, as NaOH. This MMC presented a maximum PHA accumulation capacity of 53 wt% with 27 Cmol% HV. Accumulation experiments performed with added NaCI at concentrations of 7, 13 and 20 g/L shown that this salt provoked a decrease of the biomass PHA production rate, with an IC50 value close to 7 g NaCl/L. The accumulated PHA was lower than the corresponding value of the assay without the addition of salt. Furthermore, the composition of the biopolymer, in terms of HB:HV ratio, changed from 2.71 to 6.37 Cmol/Cmol, which means a HV decrease between 27 and 14 Cmol%. Summarizing, the PHA accumulation by a MMC non-adapted to saline conditions affected the polymer composition and lead to lower production yields and rates than in absence of added NaCl. (C) 2015 Elsevier B.V. All rights reserved.
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Pichel, A., Fra, A., Morales, N., Campos, J. L., Mendez, R., Mosquera-Corral, A., et al. (2021). Is the ammonia stripping pre-treatment suitable for the nitrogen removal via partial nitritation-anammox of OFMSW digestate? J. Hazard. Mater., 403, 123458.
Abstract: Treating the organic fraction of municipal solid waste (OFMSW) can be performed by coupling the anaerobic digestion (AD) and partial nitritation-anammox (PN-AMX) processes for organic matter and nitrogen removal, respectively. Besides, an ammonia stripping (AS) step before the AD benefit the removal of organic matter. In the present study, the operation of two PN-AMX sequencing batch reactors with and without AS pre-treated OFMSW digestate (AS-SBR and nAS-SBR, respectively) was assessed. The specific anammox activity decreased by 90 % for increasing proportions of fed OFMSW in both cases, indicating no differences over the anammox activity whether the AS pre-treatment is implemented or not. For 100 % OFMSW proportion, the AS-SBR achieved better effluent quality than the nAS-SBR (127 +/- 88 vs. 1050 +/- 23 mg N/L) but with lower nitrogen removal rates (58 +/- 8 vs. 687 +/- 32 g N/(L.d)). Still, the latter required successive re-inoculations to obtain higher removal rates. Changes in the microbial communities were mainly correlated to sCOD/N ratios in the OFMSW, being Candidatus Brocadia the dominant anamnmox species. The results proved the AS to be a suitable pre-treatment, despite the higher sCOD/N ratios in the OFMSW digestate, achieving good synergy between the PN-AMX and heterotrophic denitrification processes.
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