In the laboratory, E-mulse 3® was selected as a surfactant because of its easy handling, good solubilization and mobilization rates of Bailin DNAPL, good behavior in alkaline conditions, compatibility with the selected oxidant and good reaction rate with DNAPL.
Three techniques for treating emulsions generated in DNAPL washing with surfactant (Fenton oxidation, alkaline hydrolysis with aeration and adsorption in activated carbon and subsequent oxidation) have been tested on the laboratory and bench scale, making it possible to pre-treat highly contaminated fluids, reuse already treated fluids and recover activated carbon.
The behavior of oxidant and surfactant mixtures has been evaluated to optimize the destruction of pollutants with the lowest reagent consumption.
2.-Know the detailed operation of the aquifer for efficient and safe reagent applications. Design infrastructures and equipment to meet these objectives.
Seven hydrogeological and six tracer tests have been carried out, adapted to the characteristics of the heterogeneous and fractured Bailín aquifer. This prior research is essential to design the tests, guarantee the contact between the reagents and the contaminants, know their evolution in time and space and adopt measures to guarantee the absence of effects on the receiving environment, in this case, the Gállego river.
An area downstream from the test area was selected to establish a “safety barrier”, where the combined action with injection of soda, oxidant, application of heat and aeration, allowed the plume originating from the test area to degrade before reaching the river.
3.-Reduce the risk to health and the environment, generated by persistent organic pollutants (POPs), by eliminating residual DNAPL.
In the overall tests, 240 kg of DNAPL have been removed from the aquifer (pumped or eliminated in situ).
The removed contaminant load could disable 2400 Hm3 (2,400,000,000,000,000 liters) of water for potable use.
With this technique, and only considering the HCH contained in the DNAPL mass removed from the aquifer, the tested layer has been prevented from discharging under the most unfavorable conditions, the mass equivalent of a period of 500 years of natural discharge into the Gállego river.
4.-Analyze the large-scale applicability of the technique from a technical, economic and environmental point of view.
The large-scale application of this technique has proven viable in Bailín. It is feasible within a period of 5 years to minimize the presence of dense phase in the aquifer, which would effectively mean ceasing to be in a permanent risk situation.
The technique is confirmed to be adaptable to other locations; currently (2023), it has been successfully applied in the Sardas detrital aquifer, with different geological conditions.
To remove the equivalent mass extracted in this test with a single oxidation test, it would have been necessary to treat the sandstone surface more than 50 times.
From an environmental perspective, the application of this methodology does not generate risks for the receiving channel. The surfactant used is biodegradable and after the use of soda and persulfate; in a few months, the aquifer has recovered the possibility of implementing a biostimulation treatment.
This technique reduces treatment periods by more than 10 times, estimating a reduction of more than 50 years in the duration of the contamination period of surface waters.
The treatment of polluted fluids in Bailín, using techniques tested on site, makes it possible to minimize external waste treatments, reuse the treated fluids and recover the active carbon used.
5.-Disseminate the results of the project to stakeholders, as well as raise general public awareness about the problem of this type of pollution, paying special attention to the project environment, affected by the pollution.
Designed for different types of groups, various activities have been organized to raise awareness about the techniques used during the pilot test. For this purpose, the following activities have been carried out:
- 10 sessions for the general public.
- 23 sessions for expert groups and project partners.
- 6 workdays with social, technical and political committees throughout the duration of the project.
- 14th International HCH and Pesticides Forum.
The main disseminations elements that were used as the project progressed have been:
- Educational posters and roll-ups.
- Audiovisual media (project video, short videos).
- Social Networks (X, Youtube).
- Website: https://lifesurfing.eu.
- Evaluation surveys.
6.-Innovate the application of the surfactant-enhanced chemical oxidation technology in DNAPL pollutants.
Ten specialized articles indexed in the JCR database have been developed, acknowledging the LIFE Project, published in high-impact journals 7 in Q1 and 2 in Q2 which have been presented at international conferences (AquaConSoil, 14th International HCH and Pesticides Forum).
These articles are available on the website: https://lifesurfing.eu
7.-Analyze replicability and transferability of the technique to other locations, by defining a strategy to multiply the impact of the results obtained for their use at other sites.
A Replicability and Transferability Plan has been prepared, which examines measures to facilitate the application of the S-ISCO technique at other sites with similar environmental issues. To achieve this, guidelines and implementation under specific conditions have been studied, particularly in porous aquifers, by evaluating surfactants and their solubility, as well as the selection of oxidizing agents and their degradation. The design process of the hydraulic system, injection equipment, and monitoring has also been investigated.
In this case and thanks to the results obtained in the LIFE SURFING project, a real example of transferability of the project was possible through a field-scale test, in the contaminated environment of the Sardas landfill, where techniques have been applied. SEAR and S-ISCO in granular medium, with geological characteristics completely different from those of the Bailín site, where the project was executed.
8.-Create a network to share, exchange and transfer knowledge and experiences for projects related to sites affected by organochlorines, POPs, POP pesticides and other pesticides.
In addition to the 14th International Forum mentioned above, it has participated in work networks whose objective is to exchange knowledge and experiences such as:
- The European LINDANET project, consisting of a work network created to share, exchange and transfer knowledge and experiences at the European level related to sites affected by lindane contamination.
- The European LIFEPOPWAT project, a pilot project that promotes the application of technology based on artificial wetlands for the treatment of water polluted with pesticides.
- The European HCH in EU project, whose objective has been to evaluate and address the presence of lindane in Europe.
In all these projects, experiences and knowledge have been exchanged through meetings, webinars or conferences.
