Nuestros investigadores

Enrique Aymerich Soler

Publicaciones científicas más recientes (desde 2010)

Autores: Alejandro Cerdán, J. M.; Tejido-Nuñez, Y.; Aymerich Soler, Enrique; et al.
ISSN 1877-2641  Vol. 12  Nº 3  2021  págs. 1357 - 1369
In this study, a systematic comparison between methanogenic and acidogenic potential tests of five waste streams from urban and agro-industrial origin was investigated. Methanogenic potential tests were performed under neutral pH (7.0) and thermophilic temperature (55 degrees C). Additionally, acidogenic potential tests consisted of mono-fermentation tests at acidic pH (5.5) and co-fermentation tests performed at alkaline pH (9.0), under thermophilic temperature (55 degrees C). The methanogenic yield increased up to 0.54 gCH(4) g(-1) CODfed while the acidogenic yield ranged within 0.04-0.24 g VFA g(-1) CODfed. The VFA (volatile fatty acids) yield was boosted when adding co-substrates that complemented the optimal C/N balance, i.e. 0.27-0.36 gVFA g(-1) CODfed. Herein, highest total volatile fatty acid (tVFA) concentration was attained by microalgae biomass (MB), with 8769 mg COD L-1. During mono-fermentation tests under acid pH, butyric acid was promoted as main fermentation product, which varied between 1526 and 6114 mg COD L (-1), whereas shifting to alkaline pH in co-fermentation tests promoted acetic production, from 3387 to 5415 mg COD L-1. The results of the current research revealed a significant potential of organic waste to enrich the carboxylic platform (e.g. acetic and butyric acids), which have higher industrial applicability and economic potential than methane. [GRAPHICS] .
Autores: Tejido-Nunez, Y. , (Autor de correspondencia); Aymerich Soler, Enrique; Sancho Seuma, Luis; et al.
ISSN 2211-9264  Vol. 49  2020 
Microalgae biotechnology is of increasing importance and a central application concerns the treatment of wastewater. Here, its implementation in a recirculating aquaculture system (RAS) to lower the discharge of wastewater is studied. To better cope with external variations in culture conditions, a co-cultivation of two species of microalgae, Chlorella vulgaris and Tetradesmus obliquus, was used to obtain a more reliable and robust culture and was compared to monocultures. This approach was tested using RAS water both under sterile and non-sterile conditions at laboratory scale and then compared to a co-culture at pilot-scale in an open thin-layer photobioreactor. Performance of cultures was tested in terms of microalgae growth and nutrient removal efficiency. Furthermore, to better understand the interaction between environmental variables and each microalgae species, their relative frequencies in co-cultures as well as the presence of protozoa and bacteria were monitored. All growth experiments were carried out successfully and, unlike in a previous study, no crashes were observed. However, shifts in species frequency in co-cultures indicated that the two species were differentially affected by cultivation conditions. Despite nutrient limitation, the pilot-scale cultivation had a high productivity (13.3¿g¿m¿2 d¿1) and final dry weight (11.1¿g¿l¿1) after 29¿days and demonstrated its suitability for RAS water treatment.
Autores: Tejido-Nunez, Y., (Autor de correspondencia); Aymerich Soler, Enrique; Sancho Seuma, Luis; et al.
ISSN 0925-8574  Vol. 136  2019  págs. 1 - 9
The ongoing and increasing worldwide demand for fish has caused a steady increase in aquaculture production during the last decades. This emphasizes the importance of farming systems with a low ecological footprint, like recirculating aquaculture systems (RAS), which are an alternative to traditional open systems. Furthermore, implementing microalgae treatments in RAS, sustainable water management and low discharge of concentrated wastewater could be achieved, allowing its reuse in the system. The influence of three factors on microalgae treatment efficiency in RAS water were studied: i) microalgae species (Chlorella vulgaris, Tetradesmus obliquus), ii) water pre-treatment (sterile filtration), and iii) sampling location within the RAS (e.g. from fish tank, after UV-disinfection, etc.). To this end, fully factorial, replicated cultivations were carried out in 100-ml flasks, and nutrient removal, microalgae growth, and density of bacteria and protozoa were measured for up to 18 days. Results show that both species are able to grow in RAS water and effectively remove nutrients in it, yet their performance depended greatly on water quality. In sterile RAS water, growth and nutrient removal efficiency of C. vulgaris surpassed that of T. obliquus. In non-sterile RAS water, the pattern reversed because of grazing protozoa. The location of sampling within the RAS had no discernible effect on microalgae growth or nutrient removal efficiency. The results confirm that a microalgae-based technology to treat and valorise RAS water is technically feasible, yet caution that inferences made can be reversed depending on the choice of the species and the pretreatment of the RAS water prior to cultivation.
Autores: Singh, A. , (Autor de correspondencia); Sawant, M.; Kamble, S. J.; et al.
ISSN 0944-1344  Vol. 26  Nº 21  2019  págs. 21172 - 21188
A Decentralized Wastewater Treatment System (DEWATS) provides an economically feasible and efficient wastewater treatment solution especially in developing countries. It has an enormous potential for developing a sustainable environmental sanitation system. In this study, the treatment efficiency of eight DEWATS plants was evaluated in the state of Maharashtra, India, for their performance in terms of selected physico-chemical parameters of the wastewater. Although the efficiency of some of the plants was lower than that reported in literature, the effluent quality of all the plants was within the permissible discharge limits of the Central Pollution Control Board for all the parameters. Comprehensive assessment of Plant I was carried in terms of its technical and socio-economic aspects. Moreover, LCA tool has been utilized to evaluate the environmental impacts of the operation stage of DEWATS. The midpoint, CML 2001 (April 2015) methodology was adopted, in which 11 impact categories were considered. From the life cycle impact assessment and interpretation, the main impacts are identified as releases of COD, P-PO43-, and N-NH4+ to water bodies and disposal of sludge. Due to negligible energy consumption, the operation stage was found to be less damaging to the environment. It was concluded that DEWATS can be a good alternative for treating wastewater with negligible energy and chemical consumption.
Autores: Starkl, M., (Autor de correspondencia); Anthony, J. ; Aymerich Soler, Enrique; et al.
ISSN 0195-9255  Vol. 71  2018  págs. 132 - 141
Inadequate sanitation is amongst the causes of escalating pollution problems in developing countries, as municipal wastewater treatment systems remove only a fraction of pollutants that could be removed with best available technologies (BAT). Although BAT is a proven instrument of environmental policies, its potential for municipalities remains largely unused in developing countries. In order to ease its implementation, the paper developed a simplified assessment approach towards identifying an approximating of BAT in terms of a "flexible BAT" (FlexiBAT), which is based on the identification of national reference plants assessed with respect to pollutant removal (environmental impact, health impact), costs (economic viability, affordability) and social acceptability. The concept was tested for 58 case studies in India, where none of the technologies passed all tests for FlexiBAT. Therefore, there is a need to improve or develop better and more innovative technologies. Amongst the most promising ones, membrane bioreactors provided good physical water quality, but costs were high, while for moving bed biofilm reactors costs were low, but water quality was insufficient. Conventional onsite systems require separate consideration. In order to ease the identification of FlexiBAT, a national environmental information system with data from the regular monitoring of existing plants would be needed.
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: Singh, A.; Kamble, S. J., (Autor de correspondencia); Sawant, M.; et al.
ISSN 0944-1344  Vol. 25  Nº 3  2018  págs. 2552 - 2569
Moving bed biofilm reactor (MBBR) is a highly effective biological treatment process applied to treat both urban and industrial wastewaters in developing countries. The present study investigated the technical performance of ten full-scale MBBR systems located across India. The biochemical oxygen demand, chemical oxygen demand, total suspended solid, pathogens, and nutrient removal efficiencies were low as compared to the values claimed in literature. Plant 1 was considered for evaluation of environmental impacts using life cycle assessment approach. CML 2 baseline 2000 methodology was adopted, in which 11 impact categories were considered. The life cycle impact assessment results revealed that the main environmental hot spot of this system was energy consumption. Additionally, two scenarios were compared: scenario 1 (direct discharge of treated effluent, i.e., no reuse) and scenario 2 (effluent reuse and tap water replacement). The results showed that scenario 2 significantly reduce the environmental impact in all the categories ultimately decreasing the environmental burden. Moreover, significant economic and environmental benefits can be obtained in scenario 2 by replacing the freshwater demand for non-potable uses. To enhance the performance of wastewater treatment plant (WWTP), there is a need to optimize energy consumption and increase wastewater collection efficiency to maximize the operating capacity of plant and minimize overall environmental footprint. It was concluded that MBBR can be a good alternative for upgrading and optimizing existing municipal wastewater treatment plants with appropriate tertiary treatment.
Autores: Irizar Picón, Juan; Zambrano, J.; Carlsson, B.; et al.
ISSN 1364-8152  Vol. 71  2015  págs. 148 - 158
The literature shows a diversity of real-time algorithms for automatic detection of bending-points in batch-operated waste treatment systems. In this study a new methodology is proposed for tuning the parameters of these algorithms when uncertainty specifications are considered at the outset. In this method the effects of slow and fast dynamic responses on the shape of signal trajectories were treated separately in order to cover via simulation all possible operating scenarios for a real situation. Long-term uncertainty and steady-state simulations were combined to derive probability distributions for biomasses. These probability distributions were then merged with short-term uncertainty to run one-cycle random simulations with which to reproduce the entire diversity of signal trajectories. Finally, an optimisation problem was formulated in terms of the algorithm parameters. The methodology was satisfactorily applied to tune an algorithm for detection of bending-points in an Autothermal Thermophilic Aerobic Digestion (ATAD) process. (C) 2015 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: Raposo, F.; Borja, R.; Cacho, J.A.; et al.
ISSN 0165-9936  Vol. 51  2013  págs. 127 - 143
This first international proficiency-testing scheme evaluated the analytical performance and the state of practice in measurement of volatile fatty acids in aqueous samples. Gas chromatography and high-performance liquid chromatography were used by 25 laboratories from 15 different countries. Two reference materials were selected for analysis. The performance of each laboratory was assessed by the internationally-accepted z-score. The overall performance was rather poor. Among the causes of poor analytical performance, human errors and inadequate calibration were probably the major problems encountered. (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.
Autores: Donoso-Bravo, A.; Perez-Elvira, S.; Aymerich Soler, Enrique; et al.
ISSN 0960-8524  Vol. 102  Nº 2  2011  págs. 660 - 666
Laboratory and pilot-scale experiments were carried out in order to evaluate the influence of thermal pre-treatment time on waste-activated sludge properties and anaerobic biodegradability. Six experimental conditions were analyzed from 0 to 30 min of hydrolysis time. Solubilization of macromolecular compounds, changes in the main sludge properties and anaerobic biodegradability of the sewage sludge were evaluated. A similar carbohydrate solubilization degree was achieved, from 53% to 70% and 59% to 75% for lab- and pilot-scale experiments, respectively. In the case of proteins, the values of solubilization were lower in the pilot-scale experiment than in the laboratory, with 31-45% and 47-70%, respectively. Ammonia and volatile fatty acid did not undergo important changes; however the sludge dewaterability enhanced at increased pre-treatment times. All the pre-treatment conditions had a positive effect with regard to anaerobic biodegradability and by fitting experimental data with a simplified mathematical model, it was concluded that the maximum biogas production rate is more influenced by the pre-treatment time than the total biogas production. (C) 2010 Elsevier Ltd. All rights reserved.