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Dive into the research topics where Raquel Lebrero is active.

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Featured researches published by Raquel Lebrero.


Environmental Science & Technology | 2011

A comparative analysis of odour treatment technologies in wastewater treatment plants.

José M. Estrada; N. J. R. Bart Kraakman; Raúl Muñoz; Raquel Lebrero

Biofiltration, activated sludge diffusion, biotrickling filtration, chemical scrubbing, activated carbon adsorption, regenerative incineration, and a hybrid technology (biotrickling filtration coupled with carbon adsorption) are comparatively evaluated in terms of environmental performance, process economics, and social impact by using the IChemE Sustainability Metrics in the context of odor treatment from wastewater treatment plants (WWTP). This comparative analysis showed that physical/chemical technologies presented higher environmental impacts than their biological counterparts in terms of energy, material and reagents consumption, and hazardous-waste production. Among biological techniques, the main impact was caused by the high water consumption to maintain biological activity (although the use of secondary effluent water can reduce both this environmental impact and operating costs), biofiltration additionally exhibiting high land and material requirements. From a process economics viewpoint, technologies with the highest investments presented the lowest operating costs (biofiltration and biotrickling filtration), which suggested that the Net Present Value should be used as selection criterion. In addition, a significant effect of the economy of scale on the investment costs and odorant concentration on operating cost was observed. The social benefits derived from odor abatement were linked to nuisance reductions in the nearby population and improvements in occupational health within the WWTP, with the hybrid technology exhibiting the highest benefits. On the basis of their low environmental impact, high deodorization performance, and low Net Present Value, biotrickling filtration and AS diffusion emerged as the most promising technologies for odor treatment in WWTP.


Water Research | 2010

Monitoring techniques for odour abatement assessment

Raúl Muñoz; Eric C. Sivret; Raquel Lebrero; Xinguang Wang; I.H. Suffet; Richard M. Stuetz

Odorous emissions from sewers and wastewater treatment plants are a complex mixture of volatile chemicals that can cause annoyance to local populations, resulting in complaints to wastewater operators. Due to the variability in hedonic tone and chemical character of odorous emissions, no analytical technique can be applied universally for the assessment of odour abatement performance. Recent developments in analytical methodologies, specifically gas chromatography, odour assessment approaches (odour wheels, the odour profile method and dynamic olfactometry), and more recently combined gas chromatography-sensory analysis, have contributed to improvements in our ability to assesses odorous emissions in terms of odorant concentration and composition. This review collates existing knowledge with the aim of providing new insight into the effectiveness of sensorial and characterisation approaches to improve our understanding of the fate of odorous emissions during odour abatement. While research in non-specific sensor array (e-nose) technology has resulted in progress in the field of continuous odour monitoring, more successful long term case-studies are still needed to overcome the early overoptimistic performance expectations. Knowledge gaps still remain with regards to the decomposition of thermally unstable volatile compounds (especially sulfur compounds), the inability to predict synergistic, antagonistic, or additive interactions among odorants in combined chemical/sensorial analysis techniques, and the long term stability of chemical sensors due to sensor drift, aging, temperature/relative humidity effects, and temporal variations. Future odour abatement monitoring will require the identification of key odorants to facilitate improved process selection, design and management.


Bioresource Technology | 2012

Odor abatement in biotrickling filters: Effect of the EBRT on methyl mercaptan and hydrophobic VOCs removal

Raquel Lebrero; Elisa Rodríguez; José M. Estrada; Pedro A. García-Encina; Raúl Muñoz

The performance and microbiology of a biotrickling filter (BTF) treating methyl mercaptan, toluene, alpha-pinene and hexane at the mg m(-3) level was studied at empty bed residence times (EBRT) of 50, 30, 11 and 7 s. Removal efficiencies (REs) higher than 95% were observed for MeSH, toluene and alpha-pinene even at 11 s, while hexane REs exceeded 70%. At 7 s, an irreversible damage of the microbial activity due to the accumulation of toxic metabolites resulted in a decrease of REs. The addition of silicone stabilized process performance but only re-inoculation allowed achieving a complete removal of MeSH, toluene and alpha-pinene, and hexane REs of 80%. The high K(L)a values (ranging from 38 ± 4 to 90 ± 11 h(-1)) explained the good BTF performance at such low EBRTs. A high bacterial diversity, along with a vertical distribution of the bacterial communities was observed, the main phyla being Proteobacteria, Actinobacteria, Nitrospira, Chloroflexi and Gemmatimonadertes.


Critical Reviews in Environmental Science and Technology | 2011

Odor Assessment and Management in Wastewater Treatment Plants: A Review

Raquel Lebrero; Lynne Bouchy; Richard M. Stuetz; Raúl Muñoz

The stricter environmental regulations, encroachment of residential areas on wastewater treatment plants (WWTPs), and increasing public expectations on privatized water companies have resulted in an increase in the number of public odor complaints during the last decades. Despite not being a direct cause of disease, long-term exposure to high-strength odorant emissions actually does negatively affect human health (e.g., causing nausea, headaches, respiratory problems). Therefore, the minimization and abatement of unpleasant odor emissions are becoming two of the major challenges for WWTP utilities worldwide. However, information regarding odor formation, sources, sampling, characterization, impact assessment, and control techniques is rather sparse in the literature. Therefore, there is a need for an integrated approach to odor assessment and management.


Biotechnology Advances | 2012

A sensitivity analysis of process design parameters, commodity prices and robustness on the economics of odour abatement technologies

José M. Estrada; N.J.R. (Bart) Kraakman; Raquel Lebrero; Raúl Muñoz

The sensitivity of the economics of the five most commonly applied odour abatement technologies (biofiltration, biotrickling filtration, activated carbon adsorption, chemical scrubbing and a hybrid technology consisting of a biotrickling filter coupled with carbon adsorption) towards design parameters and commodity prices was evaluated. Besides, the influence of the geographical location on the Net Present Value calculated for a 20 years lifespan (NPV20) of each technology and its robustness towards typical process fluctuations and operational upsets were also assessed. This comparative analysis showed that biological techniques present lower operating costs (up to 6 times) and lower sensitivity than their physical/chemical counterparts, with the packing material being the key parameter affecting their operating costs (40-50% of the total operating costs). The use of recycled or partially treated water (e.g. secondary effluent in wastewater treatment plants) offers an opportunity to significantly reduce costs in biological techniques. Physical/chemical technologies present a high sensitivity towards H2S concentration, which is an important drawback due to the fluctuating nature of malodorous emissions. The geographical analysis evidenced high NPV20 variations around the world for all the technologies evaluated, but despite the differences in wage and price levels, biofiltration and biotrickling filtration are always the most cost-efficient alternatives (NPV20). When, in an economical evaluation, the robustness is as relevant as the overall costs (NPV20), the hybrid technology would move up next to BTF as the most preferred technologies.


Journal of Hazardous Materials | 2011

A comparative assessment of biofiltration and activated sludge diffusion for odour abatement.

Raquel Lebrero; Elisa Rodríguez; Pedro A. García-Encina; Raúl Muñoz

The deodorization performance of a biofilter and an activated sludge diffusion (AS) system was comparatively evaluated in terms of removal efficiency (RE) and process stability at empty bed residence times (EBRT) ranging from 94 to 32s. Both bioreactors were fed with a synthetic odorous emission containing H(2)S, butanone and toluene at 23.6-43.3, 4.3-6.3 and 0.4-0.6 mg m(-3), respectively. While the outlet H(2)S concentration was always lower than 1.4 mg m(-3), the REs for butanone and toluene remained higher than 95% in both bioreactors regardless of the EBRT. The continuous supply of wastewater in the AS unit did not affect removal and appeared to be a requirement for efficient pollutant abatement. Despite the narrow carbon source spectrum treated, the AS system maintained a large bacterial diversity over time. Therefore, the results obtained confirmed the potential of AS systems as a robust and efficient biotechnology for odour treatment in WWTPs.


Water Research | 2010

H2S and VOCs abatement robustness in biofilters and air diffusion bioreactors: a comparative study.

Raquel Lebrero; Elisa Rodríguez; Maria J. Martin; Pedro A. García-Encina; Raúl Muñoz

The robustness of a conventional biofilter and an air diffusion bioreactor (ADB) was comparatively evaluated in laboratory-scale plants treating a mixture of H2S, butanone, toluene and alpha-pinene at gas residence times of 50 s. Under steady state conditions, H2S, butanone and toluene were almost completely degraded, while alpha-pinene removal did not exhibit removal efficiencies (REs) higher than 11.0 +/- 2.3%. Fluctuations in temperature from 8 degrees C to 30 degrees C did not impact significantly process performance in any of the biotechnologies tested. However, while the ADB unit was able to cope with three and six fold step increases in pollutant loadings, volatile organic compounds (VOCs) REs noticeably decreased in the biofilter when subjected to a six fold step change (i.e. 90% reduction for butanone and 30% for toluene). A process shutdown of five days resulted in the temporary loss of butanone and toluene RE in the ADB system. A lack of irrigation during five days caused a slight decrease in the biofilter REs, while a failure in the pH control system drastically affected the ADB performance. Finally, process robustness was quantified. The calculated overall risks showed that both biotechnologies were reliable for H2S and VOCs treatment in wastewater treatment plants, ADB diffusion exhibiting a higher robustness towards fluctuations commonly found under routine operation. This robustness was further confirmed by the high stability of the DGGE profiles.


Journal of Environmental Management | 2015

Selection of odour removal technologies in wastewater treatment plants: a guideline based on Life Cycle Assessment.

Carolina Alfonsín; Raquel Lebrero; José M. Estrada; Raúl Muñoz; N.J.R. (Bart) Kraakman; Gumersindo Feijoo; Ma Teresa Moreira

This paper aims at analysing the environmental benefits and impacts associated with the treatment of malodorous emissions from wastewater treatment plants (WWTPs). The life cycle assessment (LCA) methodology was applied to two biological treatments, namely biofilter (BF) and biotrickling filter (BTF), two physical/chemical alternatives, namely activated carbon tower (AC) and chemical scrubber (CS), and a hybrid combination of BTF + AC. The assessment provided consistent guidelines for technology selection, not only based on removal efficiencies, but also on the environmental impact associated with the treatment of emissions. The results showed that biological alternatives entailed the lowest impacts. On the contrary, the use of chemicals led to the highest impacts for CS. Energy use was the main contributor to the impact related to BF and BTF, whereas the production of glass fibre used as infrastructure material played an important role in BTF impact. Production of NaClO entailed the highest burdens among the chemicals used in CS, representing ∼ 90% of the impact associated to chemicals. The frequent replacement of packing material in AC was responsible for the highest environmental impacts, granular activated carbon (GAC) production and its final disposal representing more than 50% of the impact in most categories. Finally, the assessment of BTF + AC showed that the hybrid technology is less recommendable than BF and BTF, but friendlier to the environment than physical/chemical treatments.


Chemosphere | 2016

Exploring the potential of fungi for methane abatement: Performance evaluation of a fungal-bacterial biofilter.

Raquel Lebrero; Juan C. López; Iiro Lehtinen; Rebeca Pérez; Guillermo Quijano; Raúl Muñoz

Despite several fungal strains have been retrieved from methane-containing environments, the actual capacity and role of fungi on methane abatement is still unclear. The batch biodegradation tests here performed demonstrated the capacity of Graphium sp. to co-metabolically biodegrade methane and methanol. Moreover, the performance and microbiology of a fungal-bacterial compost biofilter treating methane at concentrations of ∼2% was evaluated at empty bed residence times of 40 and 20 min under different irrigation rates. The daily addition of 200 mL of mineral medium resulted in elimination capacities of 36.6 ± 0.7 g m(-3) h(-1) and removal efficiencies of ≈90% at the lowest residence time. The indigenous fungal community of the compost was predominant in the final microbial population and outcompeted the inoculated Graphium sp. during biofilter operation.


Water Research | 2013

Step-feed biofiltration: A low cost alternative configuration for off-gas treatment

José M. Estrada; Guillermo Quijano; Raquel Lebrero; Raúl Muñoz

Clogging due to biomass accumulation and the loss of structural stability of the packing media are common operational drawbacks of standard gas biofiltration inherent to the traditional biofilter design, which result in prohibitive pressure drop buildups and media channeling. In this work, an innovative step-feed biofilter configuration, with the air emission supplied in either two or three locations along the biofilter height, was tested and compared with a standard biofilter using toluene as a model pollutant and two packing materials: compost and perlite. When using compost, the step-feed biofilter supported similar elimination capacities (EC ≈ 80 g m(-3) h(-1)) and CO2 production rates (200 g m(-3) h(-1)) to those achieved in the standard biofilter. However, while the pressure drop in the step-feed system remained below 300 Pa m bed(-1) for 61 days, the standard biofilter reached this value in only 14 days and 4000 Pa m bed(-1) by day 30, consuming 75% more compression energy throughout the entire operational period. Operation with perlite supported lower ECs compared to compost in both the step-feed and standard biofilters (≈ 30 g m(-3) h(-1)), probably due to the high indigenous microbial diversity present in this organic packing material. The step-feed biofilter exhibited 65% lower compression energy requirements than the standard biofilter during operation with perlite, while supporting similar ECs. In brief, step-feed biofiltration constitutes a promising operational strategy capable of drastically reducing the operating costs of biofiltration due to a reduced energy consumption and an increased packing material lifespan.

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Raúl Muñoz

University of Valladolid

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Rebeca Pérez

University of Valladolid

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Sara Cantera

University of Valladolid

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Juan C. López

University of Valladolid

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Esther Posadas

University of Valladolid

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