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Electricity driven Low Energy and Chemical input Technology foR Accelerated bioremediation

Periodic Reporting for period 3 - ELECTRA (Electricity driven Low Energy and Chemical input Technology foR Accelerated bioremediation)

Reporting period: 2021-01-01 to 2021-12-31

ELECTRA innovates the way we clean up our environment or protect it from future pollution. The ultimate aim is an improved environmental quality and human health in line with the zero-pollution goal of the Green Deal. The project is part of the EU-China flagship initiative on Biotechnologies for Environmental and Human Health. This 4-year project involves European and Chinese partners for the development of bioremediation technologies based on the principle of electromicrobiology. The consortium gathers 17 academic and industrial partners from six EU countries, an Associated Country, a Chinese company and five Chinese academic institutions.
ELECTRA will accelerate the biodegradation of several classes and mixtures of pollutants in wastewater (WW), groundwater (GW), sediment and soil. Doing so it builds on electromicrobiology to develop innovative environmental biotechnologies that improve electron transfer during microbial degradation processes under environmentally relevant conditions, leading to better elimination rates. The processes encompass bioelectrochemical systems requiring low energy input and no chemicals, or even no energy input and only a minimal addition of chemicals. A total of 14 biotechnological approaches and set-ups are investigated with the final aim to up-scale four advanced technologies, so-called “process champions”, and validate their performance in real sites in Europe and China.
The basis for successful innovation of bioelectrochemical remediation technologies are potent microbial strains and a set of methods to understand and assess the degradation performance. A considerable number of enrichment cultures of pollutant degrading microorganisms capable to oxidise arsenite, to reduce nitrate, to dehalogenate PCB-, TCE-, TCA-, TBBPA or to metabolise antibiotics have been obtained from environmental samples and are utilised in various technologies.
ELECTRA has established a catalogue of (chemical)analytical methods to assess the bioavailability and fate of pollutants in environmental matrices and treatment systems. This also includes methods to characterize microbial communities and to monitor the expression of degradative genes. Lastly, ecotoxicological tests were selected to provide an effect-based assessment of remediation technologies. Samples from EU and Chinese sites were characterised using these methods.
Within the individual treatment concept the following progress can be highlighted.
Low energy and no chemicals technologies: with this approach we targeted contaminated groundwater and soils/sediments. Two types of bioelectrochemical systems (BES) - tubular and fluidized bed- were designed and operated to successfully remove nitrate, and to oxidise arsenite present in GW to compliance with standards. Both systems are now in the piloting phase, as is a bioelectrochemical treatment for hydrocarbons and lower chlorinated solvents pollution in GW. Partners designed an effective sequential reductive/oxidative bioelectrochemical process that permitted the complete mineralization of perchloroethylene into nonharmful compounds, driving microbial dechlorinating metabolism through the use of electric currents.
Four different soil treatment concepts using the ‘Snorkel’ approach and the amendment of biochar in the soil are being tested for the removal of aromatic hydrocarbons and pesticides. Direct interspecies electron transfer (DIET) via electrically conductive materials seems to play a role here in the anaerobic oxidation of petroleum hydrocarbons in contaminated sites.
Controlled mobilisation of heavy metals can help decontaminating soil from toxic substances. Here, the application of a so-called Redox-Stat has selectively mobilized 12% of antimony in shooting range soils, which can then be safely recovered.
No energy and low chemicals technologies: these approaches work by e.g. enlarging the area of influence of electrodes in a reactive barrier for groundwater remediation. So far, (semi-)conductive iron oxides nanoparticles were synthesised and increased the conductivity of sediments up to a factor 5-8 which also improved nitrate reduction.
Further, the use of bio-palladium nanoparticles in another approach reduced halogenated and some other pharmaceuticals in wastewater by 80-95%. Test in continuous reactors for TBBPA and antibiotics are ongoing
Various other ELECTRA approaches pursue the modification of constructed wetlands to electrochemically enhanced systems for wastewater treatment. An electron-sink method for controlling the electron flow through electrochemical wetland was developed. This approach was successfully tested for the removal of pharmaceuticals residues and the reduction of chemical bulk parameters. Another technology tests alternative operational modes of horizontal subsurface flow constructed wetlands with electrochemical production of oxygen nanobubbles and direct oxygenation by oxygen/air nanobubbles.

Bioelectrochemical systems for remediation will have to compete with existing benchmark approaches. ELECTRA uses life cycle assessment and cost-effectiveness analysis to pinpoint environmental and economic advantages of the tested approaches. Initial analyses along these lines have started by compiling the underlying material and energy flows. The piloting of four technologies is ongoing and will show if ELECTRA technologies can really compete with commercially applied treatment processes based on high use of materials, chemicals or energy, such as ion exchange, adsorption or advanced oxidation..
Market uptake and implementation of ELECTRA technologies will also be governed by legal frames and market structures. It is important to know these and to interact with the relevant players in the field. A first stakeholder workshop and attendance to environmental fairs triggered this dialogue with end-users. To foster an improved understanding and acceptance for BES our efforts are also directed to the young researchers in the project. Before the Covid-19 pandemic slowed us down, we realised Young Scientists Knowledge Exchange between EU and China, mainly through research visits and hosted several Chinese students in our labs.
Some bioremediation concepts have already achieved envisaged KPIs and the results obtained at the end of the project can be beyond the initial expectations. The possibility of technology testing on-site together with local decision-makers is a major step to reliably assess the four champions along with techno-economic studies.
On the scientific dissemination, we have published 52 journal papers, further making the case for bio-electrochemical treatment options. This aspect was also highlighted in keynote or invited talks of ELECTRA key researchers. The companies in the consortium already benefited from access to new technologies and know-how, but also new market opportunities in China and Europe, even planning the creation of a novel European Chinese company. The restoration of contaminated groundwater, the supply of clean water and, more generally, a zero-pollutant environment can have a very strong social impact. The use of sustainable bioremediation has also a relevant impact, being more compatible with land use even in densely populated areas. Specifically, the wetland-based approaches solutions might help realise more resilient and biodiverse blue-green infrastructure.
Principle and schematic of a tubular BES reactor for the co-treatment of nitrate and arsenite