Skip to main content
European Commission logo print header
Contenu archivé le 2022-12-23

Comparative assessment of technologies for solar detoxification and disinfection of contaminated water

Objectif

- The objective of the joint research project is to develop the basis for an efficient technology of solar water detoxification and disinfection that makes use of dye-sensitised and catalytic photoreactions. For both the photocatalytic detoxification and the photosensitised disinfection, a light source is required. In the Mediterranean countries, the sun is a versatile non-polluting radiation source. Eventually, the application of solar radiation should make the process independent from expensive artificial light sources and power supply. A careful evaluation over a range of conditions and with a range of contaminants shall help to choose the most appropriate technology that should be reliable under the conditions found in the respective regions.
Expected Outcome

- To design, construct and test three different prototype photoreactors;
- To assess and compare feasibility and specific application potential for the three selected approaches in the Mediterranean area;
- To recommend follow-up steps to bring the technologies to the market.



Results

- Oxidative degradation of the following pesticides was tested with homogeneous and heterogeneous photocatalysts : Bromacil, EPTC, Tribufos, Atrazine, butiphos, Lindane. Tests were run both with lamps for achieving basic information and with direct sunlight that covered a range from 1 sun to 3000 - 5000 suns in a solar furnace. Photocatalysts were TiO2 (slurry and film) for OH radical generation, dyes such as methylene blue and rose bengal (homogeneous and fixed) for singlet oxygen generation, and ferric chloride/hydrogen peroxide for OH radical production. It was found that singlet oxygen was effective against some of the pesticides but reacted very slowly or not at all with the others. All pesticides were degraded with OH radical generating agents, both TiO2 and Photo-Fenton. E. coli were effectively destroyed by solar irradiation with methylene blue or ferric chloride catalyst. Dyes were fixed to supports successfully, thus there is a chance that after the water treatment process the dye does not need to be removed. Three prototypes of reactors were constructed and actually they are under on-sun-tests.
- A simple model was developed for estimating the economics of solar detoxification and disinfection. It appears that the cost of treatment with methylene blue is much less than the cost of the Fenton system which in turn promises to be much cheaper than heterogeneous phototreatment with titanium dioxide catalysts. However, these systems have different capabilities that must also be considered, and a direct comparison is not easy to achieve. The cost of heterogenized dyes and titanium dioxide catalysts have not yet been evaluated.

Follow up (so far)

- There will be further tests with other micro-organisms. Attempts will also be made to measure the efficiency of use of the sunlight in selected cases to better define the expected range of costs. The knowledge gained of these processes to ideas to design and operate engineering-scale test systems and to extend the applicability to solve further water problems.
- To determine the influence of key parameters (such as pH-value, temperature, concentration of dissolved oxygen, presence of quenching substances) on the chemical destruction of pollutants and on the killing rates of micro-organisms;
- To determine the most promising conditions for the solar photocatalytic mineralization and dye-sensitised disinfection in the prototype reactors;
- To develop approaches for the fixation of both photocatalysts and dyes and to fabricate prototype samples;
- To design, construct and test photoreactor prototypes for the solar detoxification and disinfection of polluted water according to three technological approaches : highly concentrated radiation (solar furnace applications and fixed focus applications), Hetereogenized titanium dioxide in CPC collectors and Heterogenized dyes in falling film reactors;
- To determine technical and engineering requirements for scale-up.

Thème(s)

Data not available

Appel à propositions

Data not available

Régime de financement

CSC - Cost-sharing contracts

Participants (9)