Grey water in buildings: a mini-review of guidelines, technologies and case studies

The aim of the work is to describe the state-of-the-art on the reuse of grey water at building level taking into account (i) the grey water characteristics and amounts produced, (ii) the recycling guidelines, (iii) the treatment systems and reuse technologies, also considering the removal of micro-pollutants as xenobiotic organic compounds, and (iv) an overview of case studies for developed countries. The mini-review highlights how the existing technologies allow the safe reuse of grey water. Attention must be given to the removal of micro-pollutants especially when the discharge takes place in surface water. With reference to 12 case studies of buildings which adopt non-conventional technologies with the aim to optimise energy consumptions, results showed how the use of non-conventional technologies for water is very limited. However, adopting an integrated approach to water-energy, it is possible to use more effectively the water for energy purposes as in the cases of cooling/heating systems.