The Lighthouse – From Waste to value: Regenerative Architecture for Ecological and Social Transformation in Barreiro | Architecture Thesis

Site Context

The silos are located on a triangular plot of land that was artificially constructed to extend the industrial complex. This site was strategically selected for its convenient access to both maritime and railway transport routes. To convert the original marshland into stable ground suitable for industrial activity, retaining walls were erected to shield the area from tides and river currents. After the enclosure was completed, the basin was filled with industrial waste—mainly by-products from CUF’s chemical production and dredged sediments from the riverbed.

The primary waste material used was phosphogypsum, a by-product of phosphoric acid manufacturing. Phosphoric acid played a key role in CUF’s production of fertilizers and animal feed, where it was neutralized to provide phosphorus and calcium. For every ton of phosphoric acid produced, between four and five tons of phosphogypsum were generated. Because of its availability and low cost, phosphogypsum was widely used at the time as landfill material. However, despite being largely composed of gypsum, it can also contain heavy metals and radioactive substances, posing risks of soil, air, and water contamination. Recent research, however, indicates that this material has potential for revalorization.

Final Outcome

The Lighthouse Project reimagines the existing silos as a center for soil regeneration and material recovery, processing phosphogypsum to extract valuable components for industries like paper, detergents, and agriculture. The project begins by excavating the contaminated soil, which is temporarily stored in the silos. These silos contain 21 cells with a combined capacity of 18,700 cubic meters, sufficient to hold about one-third of the soil at a time.

Following the ground floor plan, the soil is transported by conveyor belts into a washing facility. Adjacent to this, a research laboratory enables continuous testing and analysis. The material is then lifted via bucket elevators, separated, and treated with acids and leaching agents. The second silo, composed of rectangular cells of varying sizes, allows different treatment methods to be applied simultaneously to different batches.

A key aspect of the project is addressing the building’s current abandoned and unsafe condition. The plan includes engaging Barreiro’s youth—who previously vandalized the site—to redirect their energy into constructive activity. A metal workshop will allow young people to contribute to securing the building, transforming destructive behavior into creativity by producing railings, outdoor furniture, and safety elements for the site.

Once stabilized, the silos will be opened to the public. Visitors can explore the full height of the structure, observe the ongoing processes, and actively engage in the transformation. Upper levels will be dedicated to public use, offering panoramic views of the industrial operations, Barreiro, and Lisbon. Researchers will operate from the former employee facilities, working and staying on-site during studies.

After decontamination, the site will continue functioning as a soil washing and resource recovery center, receiving materials via ship, train, and truck. This ensures the project’s long-term sustainability, turning industrial waste into a valuable, renewable resource for the future.

Conclusion: Ultimately, the project illustrates the potential of revitalizing industrial heritage into a center for sustainability, innovation, and community involvement. Through soil regeneration, resource recovery, and public engagement, it converts a contaminated, abandoned site into a valuable asset for Barreiro, laying the groundwork for a greener and more creative future.

[This Academic Project has been published with text and images submitted by the student]