ARO manages blackwater (toilet water) with Wastewater Rooftop Algae Filtration Technology (WRAFT). WRAFT uses algae to absorb nutrients in the wastewater to purify the water for usage. The algae are then harvested for use as biofuels. The algae biofuel is usually in the form of ethanol. This fuel is carbon-neutral as the algae absorbed the same amount of carbon dioxide from the air as what will be released as the fuel burns. This can then be used with a regular internal combustion engine to operate. This way we can improve existing infrastructure and thereby save cost.

     Greywater (semi-contaminated water) is cleaned by using a process called photocatalytic disinfection. This process uses gold nanoparticles to react with light and form hydroxyl radicals, which stop harmful microbes from growing. This filtered water is then used for vertical farming throughout the city. Hydroxyl disinfects water by killing all small organic creatures such as bacteria. This chemically cleans the water for reuse locally for household appliances such as washing machines and for agricultural and gardening purposes.

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