Special Report: Energy and material recovery
The Environmental Engineering Group focuses on recovering energy and materials from biodegradable waste and wastewater
The strategic priorities of Horizon 2020 focus on 12 areas of high growth and innovation potential, including competitive low carbon energy, energy efficiency, and waste and water innovation. The programme encompasses the entire research and innovation cycle, supports strong partnerships to build scale and critical mass, and has a significant cross-cutting perspective.
The scientific research activities carried out by the GIA (the Spanish acronym for Environmental Engineering Group) fall within these priority areas. The group’s research focuses mainly on the valorisation of biodegradable waste to recover energy and materials, and on the efficient treatment of wastewater.
Anaerobic digestion
In the area of waste management, the GIA specialises in anaerobic digestion processes. In view of its high greenhouse gas emissions saving potential, using agricultural and other types of organic waste to produce biogas has significant environmental advantages in terms of heat and energy production, and as a biofuel. Anaerobic digestion achieves two useable products: energy (biogas) and matter (a digestate that can be transformed into compost or from which nutrients and other products can be extracted).
Our group studies co-digestion processes using different substrates to compensate for nutrient deficiencies or excesses which may occur in the digestion of a single type of waste. This approach leads to greater efficiency in biogas production and hence greater environmental and economic benefits. We also study the feasibility of applying pre-treatments that favour the hydrolysis and biodegradability of the complex compounds present in some types of waste, such as sewage sludge and cattle slurry.
Waste and wastewater
We have experimented with different types of waste (manure, food waste, supermarket waste, sewage sludge, and biodiesel waste) with the aim of optimising the process parameters involved in biogas production. Depending on the amount and quality of biogas produced, alternatives are proposed for its purification/enrichment and use as an energy source. These include using biogas for co-generation and using biomethane as a fuel, or injecting it into the natural gas network. Similarly, depending on the composition of the digestate, studies are carried out on alternative uses, principally for use in agriculture, to regenerate soil or to obtain biopolymers. The key aspect within the alternative uses for digestates is to have marketable end products that have been declassified as waste materials, and safe end products that meet environmental standards.
Our research within the field of wastewater focuses on biological and physicochemical treatments, prioritising low-energy and low chemical consumption processes, such as the use of low cost or residual adsorbents for the removal of trace pollutants. The GIA has carried out extensive research on wastewater from the steel industry and landfill leachate, and is currently focused on sewage and sewage sludge treatment.
Project participation
All this research has been conducted within the framework of different applied research projects in collaboration with numerous partners from both the public and private sectors. Our participation in the following projects is especially worth highlighting:
- The development of sustainable systems of biogas production and use in Spain (PROBIOGAS), a singular strategic project funded by the Spanish Ministry of Education and Science involving 13 R&D and innovation bodies and 16 SMEs. This research studied the potential of the biodegradable waste produced in Spain, its geographical distribution, the feasibility of developing biogas plants employing co-digestion of waste, and the potential uses of biogas;
- Energy recovery and utilisation of methane in cattle slurry co-digestion systems to reduce greenhouse gases, led by the GIA with the participation of a private company from the energy sector (Abengoa Group) and a publicly owned enterprise from the waste management sector (COGERSA). This project was funded by the Spanish Ministry of the Environment and Maritime and Rural Affairs. The project’s main goal was to reduce the greenhouse effect of gases produced by bovine cattle slurry via co-digestion with food waste, sewage sludge and glycerin from biodiesel plants in order to enhance waste biodegradability and energy efficiency. The application of ultrasound as a pre-treatment to digestion was also studied;
- Marketable sludge derivatives from sustainable processing of wastewater in a highly integrated treatment plant (END-O-SLUDG), funded by the EU’s Seventh Framework Programme, with the participation of 14 partners from industry, academia and government bodies from five European countries. This project aimed to develop energy efficient techniques for reducing sludge production and novel treatment processes to increase biogas yield and to obtain marketable, high-quality sludge products; and
- Recovery of CO2 from the gaseous emissions of waste incinerators and their use in the production of microalgae (ReCO2very), with the participation of six partners from industry and public institutions, funded by the Spanish Ministry of Economy and Competitiveness (Society’s Challenges-Collaborative Projects). This is a strategic R&D and innovation project conceived to find an innovative and integrated solution to reduce the emissions of CO2 from waste incineration by recovering CO2 via the cultivation of microalgae to produce biofuels and other forms of energy. It also aims to address the challenge that European waste treatment plants will face in the coming years in the transition towards a greener and more circular economy.
Recent research
A more recent line of research is related to air particulate matter levels and their relationship to emission sources. Certain chemical species are generally accepted as tracers for road traffic, combustion and different industries. The GIA is currently studying the content in heavy metals, total carbon (organic and elemental carbon), soluble ions, particle size distribution and morphology of particulate matter (PM10 and PM2.5). Air mass origins can be classified by applying back trajectory analysis. This will allow us to identify pollutant sources and propose actions to optimise environmental management plans.
The GIA’s research facilities are located at the Polytechnic Engineering School on Gijón Campus, University of Oviedo. This campus forms part of what is known as Gijón’s ‘Mile of Knowledge’, which is also home to the Laboral City of Culture complex and Gijón Science and Technology Park, which is owned and managed by Gijón City Council. The majority of the region’s leading R&D and innovation companies have their headquarters or facilities in this park, thus facilitating collaboration between researchers, companies and institutions.
Professor Elena Marañón Maison
Chair in Environmental Technology
University of Oviedo
33203 Gijón, Spain
tel: +34 985 182 027
