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Argiz, L., Reyes, C., Belmonte, M., Franchi, O., Campo, R., Fra-Vazquez, A., et al. (2020). Assessment of a fast method to predict the biochemical methane potential based on biodegradable COD obtained by fractionation respirometric tests. J. Environ. Manage., 269, 9 pp.
Abstract: The biochemical methane potential test (BMP) is the most common analytical technique to predict the performance of anaerobic digesters. However, this assay is time-consuming (from 20 to over than 100 days) and consequently impractical when it is necessary to obtain a quick result. Several methods are available for faster BMP prediction but, unfortunately, there is still a lack of a clear alternative. Current aerobic tests underestimate the BMP of substrates since they only detect the easily biodegradable COD. In this context, the potential of COD fractionation respirometric assays, which allow the determination of the particulate slowly biodegradable fraction, was evaluated here as an alternative to early predict the BMP of substrates. Seven different origin waste streams were tested and the anaerobically biodegraded organic matter (CODmet) was compared with the different COD fractions. When considering adapted microorganisms, the appropriate operational conditions and the required biodegradation time, the differences between the CODmet, determined through BMP tests, and the biodegradable COD (CODb) obtained by respirometry, were not significant (CODmet (57.8026 +/- 21.2875) and CODb (55.6491 +/- 21.3417), t (5) = 0.189, p = 0.853). Therefore, results suggest that the BMP of a substrate might be early predicted from its CODb in only few hours. This methodology was validated by the performance of an inter-laboratory studyconsidering four additional substrates.
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del Rio, A. V., Pichel, A., Fernandez-Gonzalez, N., Pedrouso, A., Fra-Vazquez, A., Morales, N., et al. (2018). Performance and microbial features of the partial nitritation-anammox process treating fish canning wastewater with variable salt concentrations. J. Environ. Manage., 208, 112–121.
Abstract: The partial nitritation-anammox (PN-AMX) process applied to wastewaters with high NaCl concentration was studied until now using simulated media, without considering the effect of organic matter concentration and the shift in microbial populations. This research work presents results on the application of this process to the treatment of saline industrial wastewater. Obtained results indicated that the PN-AMX process has the capability to recover its initial activity after a sudden/acute salt inhibition event (up to 16 g NaCl/L). With a progressive salt concentration increase for 150 days, the PN-AMX process was able to remove the 80% of the nitrogen at 7-9 g NaCl/L. The microbiological data indicated that NaCl and ammonia concentrations and temperature are important factors shaping PN-AMX communities. Thus, the NOB abundance (Nitrospira) decreases with the increase of the salt concentration, while heterotrophic denitrifiers are able to outcompete anammox aftet a peak of organic matter in the feeding. (C) 2017 Elsevier Ltd. All rights reserved.
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Fra-Vazquez, A., Morales, N., Figueroa, M., del Rio, A. V., Regueiro, L., Campos, J. L., et al. (2016). Bacterial community dynamics in long-term operation of a pilot plant using aerobic granular sludge to treat pig slurry. Biotechnol. Prog., 32(5), 1212–1221.
Abstract: Aerobic granular sludge represents an interesting approach for simultaneous organic matter and nitrogen removal in wastewater treatment plants. However, the information about microbial communities in aerobic granular systems dealing with industrial wastewater like pig slurry is limited. Herein, bacterial diversity and dynamics were assessed in a pilot scale plant using aerobic granular sludge for organic matter and nitrogen elimination from swine slurry during more than 300 days. Results indicated that bacterial composition evolved throughout the operational period from flocculent activated sludge, used as inoculum, to mature aerobic granules. Bacterial diversity increased at the beginning of the granulation process and then declined due to the application of transient organic matter and nitrogen loads. The operational conditions of the pilot plant and the degree of granulation determined the microbial community of the aerobic granules. Brachymonas, Zoogloea and Thauera were attributed with structural function as they are able to produce extracellular polymeric substances to maintain the granular structure. Nitrogen removal was justified by partial nitrification (Nitrosomonas) and denitrification (Thauera and Zoogloea), while Comamonas was identified as the main organic matter oxidizing bacteria. Overall, clear links between bacterial dynamics and composition with process performance were found and will help to predict their biological functions in wastewater ecosystems improving the future control of the process. (c) 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1212-1221, 2016
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Palmeiro-Sanchez, T., del Rio, A. V., Fra-Vazquez, A., Campos, J. L., & Mosquera-Corral, A. (2019). High -Yield Synthesis of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Copolymers in a Mixed Microbial Culture: Effect of Substrate Switching and F/M Ratio. Ind. Eng. Chem. Res., 58(48), 21921–21926.
Abstract: The accumulation capacity of a mixed microbial culture (MMC) is affected if the substrate used in the accumulation experiments differs from the one used in the enrichment. For this reason, the effect of substrate switching was studied to determine the versatility of an MMC enriched in a mixture of volatile fatty acids (VFA(max)) to overcome this problem. The MMC was enriched using a VFA(max) composed of 48.3:24.3:7.3:14.7 CmM acetic (HAc), propionic (HPr), butyric (HBu), and valeric (HVa) acids, respectively. The accumulation capacity was tested using single VFAs (HAc, HPr, HBu, and HVa), as well as the VFA,Um used in the enrichment. The accumulation capacities were 52.8 +/- 4.7, 48.8 +/- 4.3, 45.2 3.0, 48.4 +/- 1.0, and 54.5 +/- 8.0 wt% for HAc, HPr, HBu, HVa, and rVFA(max) espectively, with polymer compositions of 50.6 15.1, 0.4 0.1, 63.2 1.5, 0.3 0.0, and 2.0 0.7 g 3-HB/g 3-14V, following the same order. The average yields were 0.84 0.08, 0.76 +/- 0.09, 0.74 0.02, 0.70 +/- 0.01, and 0.68 +/- 0.09 CmolpHA/CmolvF, for HVa, VFAmX, HAc, HBu, and HPr, respectively. The feed -to -microorganism (F/M) ratio showed that values of 1-7 CmolvFA/(Cmolx) in the accumulation experiments led to the optimal yields. Based on the results obtained, it seems feasible to enrich an MMC able to produce tailormade biopolymers from different VFAs at high yields.
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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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