This study tested new GreenDune photobioreactors to clean urban wastewater in a pilot project at a wastewater treatment plant in Portugal. The system effectively removed up to 95% of the main wastewater pollutant, ammonium, in as little as 24 hours. The treated water could be reused for various purposes, including seed production and restricted area irrigation. The resulting biomass was rich in proteins and carbohydrates, suitable for making biofuels and biofertilizers. The GreenDune system was more environmentally friendly compared to the existing treatment system, with significantly lower environmental impacts. While it may not entirely replace conventional wastewater treatment, it can be used alongside it, reducing environmental impact and costs, especially in rural or developing areas where traditional treatment systems may not be available.