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Colloidal Iron Oxide Nanoparticles for the REclamation of Toxic Metal Contaminated GROUNDwater Aquifers, Drinking Water Wells, and River Bank Filtrations

Periodic Reporting for period 2 - REGROUND (Colloidal Iron Oxide Nanoparticles for the REclamation of Toxic Metal Contaminated GROUNDwater Aquifers, Drinking Water Wells, and River Bank Filtrations)

Okres sprawozdawczy: 2017-03-01 do 2018-12-31

The basic concept of our technology is the creation of an adsorptive in situ barrier in order to immobilize toxic metal groundwater contaminations. This barrier is made of iron oxide nanoparticles (NPs), which are injected into sediments as colloidal suspension. After injection, the NPs form stable deposits within the aquifer, like a filter, through which the contaminated groundwater flows. During the passage, the heavy metals are adsorbed and thereby immobilized, cleaning the downstream groundwater. The main objective of Reground is the first field application and near-market replication of this innovation and therefore restoring contaminated groundwater aquifers. To do so, we produced Iron oxide NPs that have high adsorption capacity over long-term exposure times, and then inject these NPs in contaminated aquifers. We monitored the efficiency of the innovation by measuring contamination levels in groundwater after application. We then actively commercialized REGROUND via a subsequent Business Plan (BP) and a spin-off company. The REGROUND technology, due to its low costs and wide applicability, will be made highly available. This will enable immobilization of toxic metal contaminations at sites which were left untreated so far due to technical or economic reasons.
From the beginning of the project, > 40 different potential NP suspensions have been synthesized, tested, and characterized. These NPs are tested to meet the criteria for a successful application: they should form a stable suspension in liquid, be small enough to pass through the pores in soil, and provide a large surface area to adsorb heavy metal contaminations. In addition, Reground NPs shall contain no additional toxic elements. Also, we ensured that each NP production process can be performed at industrial-scale and yet meeting the above-mentioned criteria. This up-scaling process is a central focus of Reground technology, because one may produce such NPs with pure, analytical-grade materials in laboratory, but producing several tons of such particles with industrial-grade materials and yet fulfilling the above criteria with low, competitive price is a difficult task. Reground has successfully produced such environmental-friendly particles with industrial-grade materials.
In order to ensure their applicability to each environment, each potential Reground NP suspension was going through a set of laboratory tests. These tests examine the stability, mobility, reactivity, and safety of NPs using materials taken from target aquifers. Briefly, in stability tests, we measured the sedimentation time of NPs in contact with tap water and with groundwater from the aquifer. Therefore, one can avoid injection of unstable suspension that may clog the pore space. Mobility tests provide us with prediction of effective radius of influence (ROI) around well. In reactivity tests, we measured the adsorption of heavy metals to NPs in both batch and column to determine the amount of nanomaterials to be produced and injected to the aquifer according to the remediation target. Additionally, the effect of Reground NPs on living organisms was tested before application to the field. For example, we investigated the ecotoxicity of our NPs to terrestrial and aquatic organisms and found that Reground NPs are of low toxicity in the organisms tested in vivo and in the in vitro assays included in this project.
Another key focus on Reground is the first-time application in full field-scale. During the project, we tested our technology in four different countries. In Spain and in Portugal, two contaminated aquifers were treated using our nanoparticles. In each of these sites, after a pilot study, where the technical design of the injection equipment and NP migration were tested, a large-scale remediation application was carried out. In each aquifer ca. 100 cubic meters of optimized NP suspension were injected. Up to six months monitoring in these contaminated sites proved that the defined remediation goal was successfully achieved. We also applied out technology in Iran, where geogenic Arsenic contaminated an aquifer, and in Germany, where our technology was applied directly on an active industrial site.
Along with application in the field, Reground focused on market implementation of the technology. To this aim, in course of the project we promoted Reground using dissemination tools to public boards and other stakeholders. A Life Cycle Assessment (LCA) was prepared to evaluate the potential environmental impacts and benefits of the technology. The LCA quantifies many indicators such as global warming potential and energy demand, and provides additional material for the promotion of REGROUND, as well as for regulatory compliance. Finally, we performed market assessments, and compiled a business plan for the spin-off company. The consortium has taken additional actions in order to familiarize the coordination team with the basics of entrepreneurship and business development. The coordination team of REGROUND has been selected to participate in two accelerator programs for startups, of which they successfully graduated.
An important challenge in NP-based technologies for groundwater remediation is the issue of particle mobility. Normally NPs such as nZVI show good mobility in column tests. However, when they are injected into the aquifer the resulting ROI is low (sometimes below 1 meter). Thus, many wells are to be drilled to build a reactive barrier. In contrast, Reground NPs showed excellent mobility in both laboratory and field conditions. Indeed, even our diluted NPs can travel up to 4 meters in the aquifer. Total of six pilot- and large-scale applications in different aquifers have confirmed the mobility of our particles. Assuming a conservative ROI of 2.5 meters, ca. 6 times less number of wells are required compared to the case where the ROI is 1 meter, which significantly impacts the costs of operation.
Another advantage of Reground is the devising of a set of decision-making protocols for production and application of NPs. These protocols simplify the process to decide what modifications (in NPs and in the application scenario) are required based on aquifer properties.
More importantly, Reground offers a solution for remediation of heavy metal contaminated aquifers that previously were left untreated due to economical or technical reasons. Many of target sites are located in active industrial locations. Alternative remediation such as pump&treat or soil excavation are extremely expensive due to long-term interruption to activities of industries on site. Reground solution does not require long-term operation, and even during the injection, we do not interfere with daily activities of the site.
Reground is bringing a novel, green and near-market water eco-innovation into the European markets, and beyond. In order to make this possible, the TRL of our technology has been be upgraded in several steps from 4 to 7. As an example, we have started with lab-scale application of NPs and moved to pilot-scale of ca. 20m3 of NP suspension to build a small barrier. The main application with size of > 100m3 of NP suspension will fit into TRL 7. Therefore, we have upgraded our laboratory tests to larger scale and demonstrated that it can be applied in relevant environments as a new tool for the immobilization of toxic metal contaminations.