Raul Muñoz

Raul Muñoz
Universidad de Valladolid | UVA · Departamento de Ingeniería Química y Tecnología del Medio Ambiente

PhD Enviromental Biotechnology

About

402
Publications
108,189
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13,311
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Introduction
Dr. Muñoz holds a PhD in Environmental Biotechnology from Lund University (2005). Raúl is Full Professor of the Department of Chemical Engineering and Environmental Technology at the University of Valladolid. His main fields of expertise are biological gas treatment, biogas upgrading and wastewater treatment in algal-bacterial photobioreactors. Over the last 15 years, Raúl has published 264JCR papers (H index = 58), 33 book chapters, 140 International Conference proceedings.
Additional affiliations
September 2014 - December 2014
Universidad de La Frontera
Position
  • Invited Professor
August 2013 - February 2014
Metropolitan Autonomous University
Position
  • Invited Professor
July 2007 - October 2007
Nanyang Technological University
Position
  • Invited Professor

Publications

Publications (402)
Article
Full-text available
The lack of tax incentives for biomethane use requires the optimization of both biogas production and upgrading in order to allow the full exploitation of this renewable energy source. The large number of biomethane contaminants present in biogas (CO2, H2S, H2O, N2, O2, methyl siloxanes, halocarbons) has resulted in complex sequences of upgrading p...
Article
The influence of biogas flow rate (0, 0.3, 0.6, and 1.2 m(3) m(-2) h(-1)) on the elemental and macromolecular composition of the algal-bacterial biomass produced from biogas upgrading in a 180 L photobioreactor interconnected to a 2.5 L external bubbled absorption column was investigated using diluted anaerobically digested vinasse as cultivation m...
Article
The potential of a bioscrubber composed of a packed bed absorption column coupled to a stirred tank denitrification bioreactor (STR) was assessed for 95 days for the continuous abatement of a diluted air emission of N2O at different liquid recycling velocities. N2O removal efficiencies of up to 40 ± 1 % were achieved at the highest recirculation ve...
Article
This work aimed at integrating the anaerobic digestion of food waste (FW) with photosynthetic biogas upgrading at pilot scale in order to obtain a high quality biomethane and a nutrient-laden algal biomass as the main byproducts from FW treatment. The performance of a 100 L anaerobic digester treating food waste integrated via raw biogas and digest...
Article
Full-text available
The abatement of indoor volatile organic compounds (VOCs) represents a major challenge due to their environmental risk, wide nature and concentration variability. Biotechnologies represent a cost-effective, robust and sustainable platform for the treatment of hazardous VOCs at low and fluctuating concentrations. However, they have been scarcely imp...
Article
Full-text available
Anaerobic digestion can biotransform the biodegradable fraction of sewage sludge into biogas, while the symbiotic action of algal-bacterial consortia can remove both the CO2 and H2S from biogas and nutrients from digestate. A 100 L anaerobic digester operated at 20 days of retention time coupled with a 180 L high-rate algal pond (HRAP) engineered t...
Article
Full-text available
The utilization of methanotrophic haloalkaliphilic bacteria for the production of ectoine in waste treatment plants has demonstrated a great potential to upgrade the traditional use of biogas as energy vector and the current industrial routes for the production of this high added-value chemical (600–1000 €·kg⁻¹). However, the influence of socio-eco...
Article
The present work investigated for the first time the feasibility of the anoxic biodegradation of siloxanes (hexamethyldisiloxane, L2; octamethyltrisiloxane, L3; octamethylcyclotetrasiloxane, D4; and decamethylcyclopentasiloxane, D5) in a two-phase partitioning biotrickling filter (TP-BTF) using silicone oil as the organic phase. The influence of th...
Article
Full-text available
The hazard and operability analysis (HAZOP) is one of the most popular approaches for risk management, although weaknesses such as the limited number of risk factors considered, the inaccuracy of experts’ opinions or the limited process knowledge might compromise the quality of the results. In this context, conventional HAZOP analysis can be improv...
Article
In this work, the validation of a Computational Fluid Dynamics (CFD) model coupled with a 3D computational tomography (CT) bed description of the gas flow field inside a packed column used for gas biofiltration was conducted using a low-cost metal oxide sensor. The validation was carried out in terms of gas residence time distribution (RTD), which...
Article
The influence of suspended solids and pH in anaerobically digested piggery wastewater on membrane-based NH3 extraction was evaluated in batch tests. The increase in pH in the anaerobic broth from 8 to 9 resulted in an increase in NH3 removal efficiencies from 15.8% ± 0.1% to 20.9% ± 0.4% regardless of the suspended solids. The influence of membrane...
Article
The use of microalgae-bacteria consortia (MBC) for wastewater treatment have received increasing attention because of its high capacity for nutrients and organic matter removal, using sunlight as an energy source, through self-sufficient oxygen production provided by photosynthesis. This review addresses the research hotspots and main challenges of...
Article
Biogas-based biopolymer production represents an alternative biogas valorization route with potential to cut down plastic pollution and greenhouse gas emissions. This study investigated for the first time the continuous bioconversion of methane, contained in biogas, into poly(3-hydroxybutyrate) (PHB) by a mixed methanotrophic culture using an innov...
Article
Full-text available
This work systematically compared the potential of a conventional fungal biofilter (BF) and a fungal biotrickling filter (BTF) for the abatement of a mixture of hydrophobic volatile organic compounds (VOCs). Candida subhashii was herein used for the first time, to the best of the author's knowledge, to remove n-hexane, trichloroethylene, toluene an...
Article
Full-text available
The feasibility of producing volatile fatty acids (VFAs) from five commercial bioplastics via acidogenic fermentation by a non-pretreated anaerobic sludge was investigated. Mesophilic, anaerobic, acidogenic batch assays at 1, 10 and 20 g/L feed concentrations revealed the feasibility of producing VFAs from polyhydroxyalkanoates (PHA), i.e., PHB and...
Article
Biogas desulfurization is in many cases the main purification step required for energy generation. This is the case of wastewater treatment plants, waste management facilities or intensive livestock farms where the produced biogas is burned in situ to generate thermal and electrical power. The potential of compact H2S/CO2 absorption units coupled t...
Article
The feasibility of producing volatile fatty acids (VFAs) from five commercial bioplastics via acidogenic fermentation by a non-pretreated anaerobic sludge was investigated. Mesophilic batch acidogenic assays were set up for PHB, PHBV, PLA, PCL, PBS at 1.0, 10.0 and 20.0 g/L. The results obtained showed the feasibility of producing VFAs from PHB and...
Article
High rate algal ponds (HRAPs) can efficiently treat digestates but large area footprints limit their wider application. Deep HRAPs combining sunlight with light-emitting diodes (LEDs) can reduce area requirements if enough light is supplied for microalgae photoaeration. In this work, microalgae and bacterial communities were characterized in-depth...
Article
Nowadays, piggery wastewater (PWW) management still represents an unsolved global environmental problem. Photosynthetic processes have emerged as an innovative biological platform capable of performing a cost-effective treatment of wastewater with a concomitant assimilation of nutrients into biomass. In this work, the performance of a purple photot...
Article
Full-text available
In regions highly dependent on fossil fuels imports, biomethane represents a promising biofuel for the transition to a bio-based circular economy. While biomethane is typically produced via anaerobic digestion and upgrading, biomethanation of the synthesis gas (syngas) derived from the gasification of recalcitrant solid waste has emerged as a promi...
Article
The global quest for sustainability in industrial activities and waste management has recently boosted biogas production worldwide. However, the rapid decrease in the levelized cost of electricity of renewable energies will soon entail electricity prices from biogas much higher than those from solar or wind power. In this context, the upgrading of...
Article
Full-text available
Wastewater-based epidemiology has shown to be a promising and innovative approach to measure a wide variety of illicit drugs that are consumed in the communities. In the same way as for illicit drugs, wastewater-based epidemiology is a promising approach to understand the prevalence of viruses in a community-level. The ongoing coronavirus disease...
Article
Full-text available
This study proposed a lactate-based two-stage anaerobic digestion (AD) process to enhance bioenergy production rate from food waste (FW) and investigated the effect of inoculum addition and culture pH on hydrolysis-acidogenesis and further methanization. A series of batch fermentations were performed with an enriched lactate-producing consortium an...
Article
Full-text available
The application of biogas as a low-priced substrate for the production of ectoines constitutes an opportunity to decrease their production costs and to enhance the viability of anaerobic digestion. The influence of operational conditions on CH4-biogas biodegradation and on ectoines production yields was assessed in continuous pilot bubble column bi...
Article
Dark fermentation is gaining importance as a bioprocess able to valorize different organic wastes/wastewaters through the co-production of organic acids and biogenic hydrogen (bioH2). In this study, the process performance and microbial community structure of a mesophilic lab-scale fermenter inoculated with an enriched hydrogenogenic consortium and...
Article
The effect of the inoculum and operational pH on the hydrolysis-acidogenesis of food waste (FW) and on the further biomethanization of the resulting acidogenic broths was investigated. A series of batch fermentations was performed with and without inoculum (enriched lactate-producing onsortium) addition under controlled (5.7) and uncontrolled pH (i...
Article
Full-text available
Methylocystis parvus OBBP accumulates polyhydroxybutyrate (PHB) using methane as the sole carbon and energy source. In this work, the feasibility of producing (R)-3-hydroxybutyric acid (R3HBA) via intracellularly accumulated PHB through depolymerization (in-vivo) was investigated. Results showed that a PHB to R3HBA conversion of 77.2 ± 0.9% (R3HBA...
Chapter
Full-text available
The water sector is in the middle of a paradigm shift from focusing on treatment and meeting discharge permit limits to integrated operation that also enables a circular water economy via water reuse, resource recovery, and system level planning and operation. While the sector has gone through different stages of such revolution, from improving ene...
Article
Full-text available
The physical/chemical abatement of gas pollutants creates many technical problems, is costly and entails significant environmental impacts. Biological purification of off-gases is a cheap and ecologically safe way of neutralization of gas pollutants. Despite the recent advances, the main technological challenge nowadays is the purification of volat...
Article
Full-text available
This work evaluated, for the first time, the performance of an integral microalgae-based domestic wastewater treatment system composed of an anoxic reactor and an aerobic photobioreactor, coupled with an anaerobic digester for converting the produced algal-bacterial biomass into biogas, with regards to the removal of 16 contaminants of emerging con...
Article
Full-text available
The design of efficient cultivation strategies to produce bioplastics from biogas is crucial for the implementation of this biorefinery process. In this work, biogas-based polyhydroxybutyrate (PHB) production and CH4 biodegradation performance was investigated for the first time in a stirred tank bioreactor inoculated with Methylocystis parvus OBBP...
Article
Full-text available
New odour prevention strategies in wastewater treatment facilities need to be investigated to find effective and low-cost technologies for the control of malodorous emissions. In this study, the potential of activated sludge (AS) and oxidized nitrogen (N-NOx) recycling as an environmentally-friendly and cost-effective strategy for the prevention an...
Chapter
Biogas has received an increasing attention in the past decade as a renewable and sustainable energy vector that can be used for the generation of household heat, steam, and electricity in industries or as a natural gas substitute after upgrading. The raw biogas has multiple impurities at varying concentrations that limit the widespread use of this...
Chapter
The increasing number of microalgae-based applications has contributed for development of new models to describe the complex interactions taking place in mixed algal-bacterial wastewater treatment systems. Mathematical models contribute to system optimization in terms of operation and control. The goal of this work is modeling and simulation of an...
Article
Full-text available
Ammonia recovery from synthetic and real anaerobic digestates was accomplished using hydrophobic flat sheet membranes operated with H2SO4 solutions to convert ammonia into ammonium sulphate. The influence of the membrane material, flow rate (0.007, 0.015, 0.030 and 0.045 m3 h−1) and pH (7.6, 8.9, 10 and 11) of the digestate on ammonia recovery was...
Article
Full-text available
The capacity of haloalkaliphilic methanotrophic bacteria to synthesize ectoine from CH4-biogas represents an opportunity for waste treatment plants to improve their economic revenues and align their processes to the incoming circular economy directives. A techno-economic and sensitivity analysis for the bioconversion of biogas into 10 t ectoine·y–1...
Article
Anaerobic digestion (AD) is a robust biotechnology for the valorisation of organic waste into biogas. However, the rapid decrease in renewable electricity prices requires alternative uses of biogas. In this context, the engineering of innovative platforms for the bio-production of chemicals from CH4 has recently emerged. The extremolyte and osmopro...
Article
Full-text available
The biodegradation of PHB, PHBV, PBS, PBAT, PCL, PLA, and a PLA-PCL blend was systematically compared under aerobic and anaerobic aqueous conditions assessing biodegradation kinetics, extent, carbon fate and particle size influence (in the range of 100–1000 µm). Under standard test conditions, PHB and PBHV were biodegraded anaerobically (83.9±1.3%...
Poster
Full-text available
X Taller Internacional de Energía y Medio Ambiente / X International Workshop of Energy and Environment
Article
This study investigated the algal and prokaryotic community structure in an outdoors pilot High Rate Algal Pond (HRAP) that was simultaneously used for the treatment of high-strength wastewater and biogas upgrading. The algal and prokaryotic diversity was analyzed and correlated with biological and environmental parameters, and process quality indi...
Article
Full-text available
Biotechnologies have emerged as a promising solution for indoor air purification with the potential to overcome the inherent limitations of indoor air treatment. These limitations include the low concentrations and variability of pollutants and mass-transfer problems caused by pollutant hydrophobicity. A new latex-based biocoating was herein optimi...
Chapter
En este trabajo se presenta el modelado mecanístico de una configuración reactor anóxicofotobiorreactor aerobio de algas y bacterias con recirculación de biomasa para el tratamiento de aguas residuales domésticas. El modelo desarrollado permite estimar la concentración total de sólidos en suspensión en cada uno de los elementos que conforman la ins...
Article
High Rate Algal Ponds (HRAP) are a sustainable alternative for wastewater treatment. However, HRAPs must be shallow (h = 0.2–0.3 m) for adequate sunlight penetration and require relatively long hydraulic retention times (HRT, >5 d) for effective pollutant removal, which results in high area footprints. In this context, a deep HRAP (h = 1.2 m) was e...
Article
Photosynthetic biogas upgrading has recently emerged as an alternative to physical/chemical technologies in order to decrease the energy demand and environmental impact of biomethane production. Despite enclosed photobioreactors (PBRs) provide higher photosynthetic efficiency and CO2 capture capacity than open ponds, the number of studies of PBRs d...
Article
The domestic wastewater treatment performance of an integrated anoxic-aerobic photobioreactor with biomass settling and recycling, coupled with anaerobic digestion of the produced bacterial-algal biomass and biogas upgrading in the photobioreactor was investigated. Hydraulic retention time in the photobioreactor initially was 4 days (stage I and II...
Article
Full-text available
This study investigated microalgal CO2 fixation at the CO2 concentration ranging from 5 to 40% and the CO2 loading rate of 14.4 to 57.6 L/L-d. Chlorella sp. (AG10133) was selected as the optimal strain for CO2 fixation among examined algal strains. The microalgal CO2 fixation was highly dependent on the CO2 loading rate as well as CO2 concentration...
Article
Full-text available
Studies on human exposure to indoor air pollution reveal that indoor environments could be at least twice as polluted as outdoor environments. Indoor air pollution has not received as much attention than outdoor air pollution, despite an adult spending now most of the time indoors as a result of the global shift in the economy from the manufacturin...
Article
This review paper aims to identify the main sources of carbon dioxide (CO2) emissions from wastewater treatment plants (WWTPs) and highlights several technologies developed to capture CO2 in this milieu. CO2 is emitted in all the operational units of conventional WWTPs, and even after the disposal of treated effluents and sludges. CO2 emissions fro...
Article
Full-text available
The present work reviews the role of biogas as advanced biofuel in the renewable energy system, summarizing the main raw materials used for biogas production and the most common technologies for biogas upgrading and delving into emerging biological methanation processes. In addition, it provides a description of current European legislative framewo...
Article
The global environmental pollution by micro- and macro-plastics reveals the consequences of an extensive use of recalcitrant plastic products together with inappropriate waste management practices that fail to sufficiently recycle the broad types of conventional plastic waste. Biobased and biodegradable plastics are experiencing an uprising as thei...
Article
Full-text available
Biogas contain minor concentration of volatile methyl siloxanes (VMS), responsible for severe damages in turbines or internal combustion engines. Sustainable biological processes for VMS abatement are limited by the low aqueous solubility of VMS. In order this limitation, the siloxanes (D4, D5, L2 and L3) removal performance of a two-phase partitio...
Article
Microalgae-bacteria biomass cultured in wastewater is an interesting renewable material capable of metabolising nutrients from wastes into carbohydrates, proteins, and lipids through photosynthesis. Despite the interest in the valorisation of this biomass to improve the viability of microalgae-based wastewater treatment processes, very scarce resea...
Article
Extracellular Polymeric Substances (EPS) existent in anaerobic sludge proves to be a barrier for sludge liquefaction and biomass lysis efficiency. Hence EPS deaggregation heightens the surface area for the subsequent pretreatment thereby uplifting the sludge disintegration and biomethanation rate. This review documents the role of EPS and its compo...
Article
Full-text available
Packing materials used in biofiltration of gaseous pollutants represent a key design parameter, as a proper selection might not only determine the adequate performance of the system but also its cost-effectiveness. This study systematically assessed and compared the performance of a conventional plastic carrier with that of two novel clay-based mat...
Article
Full-text available
Microalgae-based technologies, usually configured as high rate algal ponds (HRAP), are efficient, sustainable, and cost-effective alternatives for wastewater treatment due to their high removal efficiencies at low energy demand, ability to recover nutrients and ease of operation. HRAPs and other photobioreactors have been intensively studied in rec...
Article
Three innovative operational strategies were successfully evaluated to improve the quality of biomethane in an outdoors pilot scale photobioreactor interconnected to an external absorption unit: i) the use of a greenhouse during winter conditions, ii) a direct CO2 stripping in the photobioreactor via air stripping during winter conditions and iii)...
Article
The potential of the filamentous N2-fixing cyanobacterium Nostoc muscorum for CO2 capture from high-loaded streams (i.e. flue gas or biogas) combined with the accumulation of glycogen (GL) and polyhydroxybutyrate (PHB), was evaluated under nutrient-sufficient and nutrient-limited conditions. N. muscorum was able to grow under CO2 contents from 0.03...
Article
Indoor air pollution has traditionally received less attention than outdoors pollution despite indoors pollutant levels are typically twice higher, and people spend 80–90% of their life in increasing air-tight buildings. More than 5 million people die every year prematurely from illnesses attributable to poor indoor air quality, which also causes m...