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Electricity driven Low Energy and Chemical input Technology foR Accelerated bioremediation

Periodic Reporting for period 2 - ELECTRA (Electricity driven Low Energy and Chemical input Technology foR Accelerated bioremediation)

Reporting period: 2020-02-01 to 2020-12-31

The ELECTRA 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 ambitions to accelerate the elimination of several classes and mixtures of pollutants in wastewater (WW), groundwater (GW), sediment and soil for improved environmental quality and human health in line with the zero-pollution goal of the Green Deal. ELECTRA builds on the research on electromicrobiology to develop innovative environmental biotechnologies that improve electron transfer during microbial degradation processes under environmentally relevant conditions. A first set of processes encompasses bioelectrochemical systems requiring low energy input and no chemicals. The second set does not require energy input and only a minimal addition of chemicals. A total of 14 biotechnological approaches and set-ups are investigated. During the project, four advanced technologies, so-called “process champions”, are selected for scale-up based on their pollutant removal performance and techno-economic studies. For each matrix, a process champion will be validated at real sites in both, Europe and China.
Preparing the ground
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. Towards these objectives, various enrichment cultures of pollutant degrading microorganisms capable to oxidise arsenite, to dehalogenate PCB-, TCE-, TCA-, TBBPA or to metabolise antibiotics have been obtained.
The consortium has established a catalogue of (chemical)analytical methods to assess the bioavailability and the 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. In this context, the access to sites, also for later piloting of technologies, was agreed with the site managers.
Technology development

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 (Fig. 1).
A bioelectrochemical well is currently developed for the removal of toluene in GW. There is also a bioelectrochemical treatment for hydrocarbons and lower chlorinated solvents pollution in GW.
Four different soil treatment concepts using the ‘Snorkel’ approach and the amendment of biochar in the soil are being tested for the removal of hydrocarbons and bromoxynil. The use of a single electrode is compared to the use of two separated electrodes for the removal of oil and micropollutants in soil.
Controlled mobilisation of heavy metals can help decontaminating soil from toxic substances. Here, the application of a so-called Redox-Stat is tested to selectively mobilize Sb in shooting range soil. The design of a redox-stat bioreactor operated as a Sequencing Batch Reactor is in progress.
No energy and low chemicals technologies: Under this theme we pursued approaches to enlarge the area of influence of electrodes, e.g. in reactive barriers for groundwater remediation. So far, (semi-)conductive iron oxides nanoparticles were synthesised. They will be applied in a multi-functional electrochemical reactor for simulating an aquifer model at lab scale.
The inclusion/immobilisation of degrading bacteria in biofilms might be beneficial for the degradation effectiveness. This can be accomplished very precisely in 3-D printed biofilm. Suitable bioinks were developed and are currently optimized. The first bacterial systems were printed and tested for the removal of chlorinated aliphatic hydrocarbons.
Various 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. Three technologies have already been identified as process champions. For those, in-depth assessments will be elaborated during their on-site piloting phase.
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. So far, ELECTRA has mapped stakeholders and developed a communication and exploitation plan that will guide our outreach activities. To foster an improved understanding and acceptance for BES our efforts are also directed to the young researchers in the project. We realised Young Scientists Knowledge Exchange between EU and China, mainly through research visits and hosted several Chinese students in our labs.
Besides the acquisition of key degraders, the catalogue of reliable (bio)analytical methods as well as ecotoxicological tools are of outmost importance to demonstrate the efficiency of bioremediation processes. The technologies developed in the frame of ELECTRA comprise a variety of designs and operational strategies specifically adapted to each contaminant mixtures and matrices. New knowledge was generated to understand how to adapt electro-bioremediation technologies to the treatment of complex mixtures of pollutants without the need of chemical reagents or without the need of energy supply. Some KPIs have already been reached 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 24 journal papers , further promoting the interest in bio-electrochemical treatment options. This aspect was also highlighted in keynote or invited talks of ELECTRA key research personnel. The companies in the ELECTRA 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.
Principle and schematic of a tubular BES reactor for the co-treatment of nitrate and arsenite