Requirements and performances of a façade integrated microalgae photo-bioreactor for domestic wastewater recycling

In the last decades new functions have been attributed to the building envelope, such as, among others, energy saving, energy production, control of environmental peaks, dynamic response to climate, communication. Beside building related energy waste and environmental emissions, addressed as top priorities by European 2020 policy, buildings are among the main contributors to freshwater consumption and pollution in cities. Alarming water consumption figures suggest the need for investigating methods for urban water purification and recycling in the near future. Among existent systems for water phyto-purification at building scale the use of microalgae photo-bioreactors seems to be a promising technology. Microalgae can grow quickly under certain condition of temperature, solar radiation, carbon dioxide, PH and nourishment. They need, among others, phosphorus and nitrogen, that are among the main pollutant of building wastewater. The strengths of the growing phase of microalgae on the building envelope represent an interesting field of research for the integration of photosynthetic phyto-purification systems on building envelopes. After describing the main characteristics of domestic wastewater and the potentiality related to the use of microalgae for wastewater treatment, the paper introduces the technological concept of an advanced façade system of a microalgae photo-bioreactors integrated in the building water system. Performances and potential application of the façade are discussed. The proposed technical element, called Algae Façade Integrated Envelope (AL.F.I.E.), is the output of a research work and a MS theses, and it is currently entering the patent process.