Indus is a biologically integrated wall, designed using computational algorithms to create ceramic scaffolds which contain microalgae for bioremediation of polluted water. In a system of interlocking modular tiles, vein-like channels are pressed into clay – inspired by the architectural form of leaves, whose surfaces distribute water evenly –and filled with a seaweed-based hydrogel with microalgae suspended in it. Computational fluid simulations further optimise the water distribution throughout the structure, enabling a more efficient algae-wastewater contact. As waste water flows over the tiles, the microalgae, which can remain active for up to several months, extract heavy metals like cadmium. The reusable tiles can be removed one by one to be maintained and refilled with fresh hydrogel.

The design of INDUS reflects our interdisciplinary approach to water pollution. The project is developed from a series of site visits, case studies and interviews conducted by our team with panchayats of artisans in India that have reiterated the need for a simple, scalable and a sustainable system to treat heavy metal contaminated wastewateron a local level. Alongside this, we have conducted experimental validation ofperformance with a range of algal species and studied uptake kinetics of heavy metals such as cadmium.

Microalgae have several mechanisms through which they are able to remove heavy metal contaminants from their environment. Exposure to low concentrations of heavy metals result in the adsorption of heavy metal ions to the cell surface as part of a passive process. However,when cells of algae or plants encounter more severe levels of pollution theymay initiate other mechanisms to try to detoxify their environment by activating phytochelatins and metallothioneins that mop up the heavy metals and deposit them within the cell where they are converted into, and stored as, nanoparticles.

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In this project we make use of the binding of heavy metal ions to charged functional groups within the algae-hydrogel matrixfor initial capture of pollutants. In future stages, the hydrogel can be treated with a second bioremediation step to upgrade heavy metals such ascadmium into valuable metal nanoparticles, leading to the formation of acircular economy, where value may be derived from waste.

The design of the Indus wall tile takes inspiration from the intricate veins on a leaf that have evolved to transportwater uniformly and efficiently to the entire plant. Each plant consists of itsown unique set of venations, just the way each panchayat would have its own version of Indus wall specific to its built environment, volume of polluted water and contaminants present. Wastewater - algal contact is optimised via the density and the distribution of the venation network. The tiles are connected using half-lap watertight joints and assembled into a wall. Each tile can beeasily removed without dismantling the entire system. Watertight connections can also be plugged in when replacing old/broken tiles, allowing the system to continue to perform while maintenance works are underway. Users are required to simply pour the heavy metal polluted water into the inlets present at the top of the wall. The water then enters the system through the branched channels running onto the algae-laden hydrogel allowing for heavy metal uptake. Water can be recirculated through the wall for further treatment, depending upon the level of contamination.

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Links of articles:

Malik S., Hagopian J., Mohite S., Lintong C., Stoffels L., Giannakopoulos S., BeckettR., Leung  C., Ruiz R., Cruz M., ParkerB.. 'Robotic Extrusion of Algae‐Laden Hydrogels for Large‐Scale Applications'. In Global Challenges. Wiley, 2019

Rawat, D.; Sharma, U.; Poria, P.; Finlan, A.; Parker, B.; Sharma, R.S.; Mishra, V. 'Iron-dependent mutualism between Chlorella sorokiniana and Ralstonia pickettii forms the basis for a sustainable bioremediation system'. ISME Communications. 21 2022, 2, 1–14

Parker,B; Rawat, D; Malik, S.; Vilatte, A.; Cruz M. 'A Design Manifesto for Bioremediation: 10 Principles for the Creationof Sustainable Systems for Environmental Benefit. AR#0 Algae Review-Bioremediation', In Atelier Luma, Arles, 2022

Credits:

Team: Shneel Malik, Brenda Parker, Marcos Cruz with UCL Bio-ID

Technical collaboration: Laura Stoffels; Anete Salmane; Kayan Patel

Fabrication (Indus 2.0): Froyle Tiles

Support: Pure Earth and Delhi University India; Algae UK and EPSRC Global Challenges Research Fund

Collaboration (Indus 2.0): Dali Al-Naeb, Aurora Tairan Li

Year: 2018-2021