Nuestros investigadores

Myriam Esteban Gutiérrez

Publicaciones científicas más recientes (desde 2010)

Autores: Garcia Aguirre, Jon (Autor de correspondencia); Esteban Gutiérrez, Myriam; Irizar Picón, Juan; et al.
ISSN 0960-8524  Vol. 282  2019  págs. 407 - 416
This study explored the potential of acidogenic fermentation of sewage sludge (SS) in an 80 L automatized pilot scale platform. A high-rate VFA production was obtained at HRT 5d and pH 9, with a volatile fatty acid (VFA) yield of 336 mg VFA g(-1) VS and a VFA productivity of 2.15 kg VFA m(-3) d(-1). During co-fermentation of SS with OFMSW, a reversible pH shift from pH 9 to pH 6, evidenced a higher acidogenic activity which promoted the butyrate metabolic pathway, with 13.97 g COD L-1 of butyric acid and a VFA peak 23.2 g COD L-1. The results show the degree of flexibility of mixed culture fermentation systems, where other pH control methods other than steady control could be used to enhance the fermentation process. Ultrafiltration was a feasible technology to obtain a VFA rich permeate where 12.3-26.6 g COD L-1 could be recovered.
Autores: Esteban Gutiérrez, Myriam (Autor de correspondencia); Garcia Aguirre, Jon; Irizar, I.; et al.
ISSN 0956-053X  Vol. 77  2018  págs. 203 - 212
Volatile fatty acid (VFA) production through anaerobic fermentation may constitute an innovative solution for organic waste management within the context of circular economy. In the present study, the evolution of individual VFA during laboratory-scale fermentation of sewage sludge (SS), winery wastewater (Www) and meat and bone meal (MBM) was assessed, focusing on the effect of pH (5.5 and 10) and temperature (35 and 55 degrees C). Up-scaling of the fermentation process was evaluated in batch operation. The latter showed that specific VFA could be produced, giving similar individual evolution to lab-scale testing. To be precise, acetic acid percentage ranged within 30-65% and increased up to 5900 mg O-2 L-1 during SS fermentation at 55 degrees C and pH 9. In addition, 60% butyric acid was reached during Www acid fermentation at 55 degrees C, which corresponded to 6670 mg O-2 L-1 concentration in the fermentation broth. Regarding valeric acid, over 20% proportion and 2700 mg O-2 L-1 were reached in MBM acid fermentation at 35 degrees C. Finally, iso-valeric maximum level ranged within 15-17% in SS alkaline fermentation at 55 degrees C, which represented a concentration close to 2000 mg O-2 L-1. Interestingly, co-fermentation of agri-food waste and SS at thermophilic temperature and alkaline pH, boosted the VFA concentration 1.7-2 fold, which suggests that anaerobic co-fermentation of substrates from different nature could give promising outcomes in full-scale operation. (C) 2018 Elsevier Ltd. All rights reserved.
Autores: Irizar Picón, Juan (Autor de correspondencia); Roche, E. ; Beltrán Calaff, Sergio; et al.
ISSN 0043-1354  Vol. 143  2018  págs. 479 - 491
Internal Circulation (IC) anaerobic systems are especially suitable when plant designs that involve both small footprints and high organic loading rates (>25 kg COD m(-3) d(-1)) are required. However, given that operating anaerobic processes at high organic loads increases their vulnerability to external disturbances, real-time indicators of the stability conditions become particularly pertinent for IC reactors. This paper addresses the design and full-scale validation of a software sensor that uses only feeding flow-rate and biogas flow-rate measurements to classify the operating conditions of the reactor as "strongly", "moderately" or "weakly" stable. A simulation-based procedure was used to design the software sensor and configure its parameters. Then, the performance of the software sensor was tested under real conditions in a full-scale IC reactor of 1679 m(3) installed in a recycled paper mill (RPM). (C) 2018 Elsevier Ltd. All rights reserved.
Autores: Astals, S.; Esteban Gutiérrez, Myriam; Fernández Arevalo, Tamara; et al.
ISSN 0043-1354  Vol. 47  Nº 16  2013  págs. 6033 - 6043
Seven mixed sewage sludges from different wastewater treatment plants, which have an anaerobic digester in operation, were evaluated in order to clarify the literature uncertainty with regard to the sewage sludge characterisation and biodegradability. Moreover, a methodology is provided to determine the Anaerobic Digestion Model No. 1 parameters, coefficients and initial state variables as well as a discussion about the accuracy of the first order solubilisation constant, which was obtained through biomethane potential test. The results of the biomethane potential tests showed ultimate methane potentials from 188 to 214 mL CH4 g(-1) CODfed, COD removals between 58 and 65% and two homogeneous groups for the first order solubilisation constant: (i) the lowest rate group from 0.23 to 0.35 day(-1) and (ii) the highest rate group from 0.27 to 0.43 day(-1). However, no statistically significant relationship between the ultimate methane potential or the disintegration constant and the sewage sludge characterisation was found. Next, a methodology based on the sludge characterisation before and after the biomethane potential test was developed to calculate the biodegradable fraction, the composite concentration and stoichiometric coefficients and the soluble COD of the sewage sludge; required parameters for the implementation of the Anaerobic Digestion Model No. 1. The comparison of the experimental and the simulation results proved the consistency of the developed methodology. Nevertheless, an underestimation of the first order solubilisation constant was detected when the experimental results were simulated with the solubilisation constant obtained from the linear regression experimental data fitting. The latter phenomenon could be related to the accumulation of intermediary compounds during the biomethane potential assay. (C) 2013 Elsevier Ltd. All rights reserved.
Autores: Aymerich Soler, Enrique; Esteban Gutiérrez, Myriam; Sancho Seuma, Luis
ISSN 0960-8524  Vol. 144  2013  págs. 107 - 114
The pilot-scale high-solids anaerobic digestion (HS-AD) of agro-industrial wastes and sewage sludge was analysed in terms of stability by monitoring the most common parameters used to check the performance of anaerobic digesters, i.e. Volatile Fatty Acids (VFA), ammonia nitrogen, pH, alkalinity and methane production. The results reflected similar evolution for the parameters analysed, except for an experiment that presented an unsuccessful start-up. The rest of the experiments ran successfully, although the threshold values proposed in the literature for the detection of an imbalance in wet processes were exceeded, proving the versatility of HS-AD to treat different wastes. The results evidence the need for understanding the dynamics of a high-solids system so as to detect periods of imbalance and to determine inhibitory levels for different compounds formed during anaerobic decomposition. Moreover, the findings presented here could be useful in developing an experimental basis to construct new control strategies for HS-AD. (C) 2013 Elsevier Ltd. All rights reserved.
Autores: Aymerich Soler, Enrique; García-Mina Freire, José María; Esteban Gutiérrez, Myriam; et al.
ISSN 1544-8053  Vol. 9  Nº 1  2012  págs. 1 - 7
Dry anaerobic digestion systems work with wastes that have a dry matter content above 20%. This technology has been used above all to treat the organic fraction of municipal solid waste making its application to the agro-food industry waste a novel approach. Co-digestion of vegetable and MBM by means of a batch system shows a good efficiency in spite of the presence of certain compounds at inhibitory levels (N-NH3 and VFA) which are detected in the process leachate.