Urban water management and recycling: assessment of current practices and development of future economic projections

Today, more than ever, dynamics of human interaction both among themselves and with nature are dictated by an economic-financial dimension that was born and nurtured on a linear Take-Make-Waste model. Far from having a moralistic intent, the paper would like to underline how, in this dimension, the yardstick is growth and profit, relatively unimportant figures if related to the concept of sustainability or better survival. Finance, an abstraction that should represent the complexity and interconnection of our planet, sins of pride in believing that roles are reversed, and that nature obeys rules written on paper by economists. As a consequence of capitalism, the social problem evident today is, unfortunately, the proof. What is measured inevitably becomes the unit upon which targets are set, the result are goals which are orphan of dimensions that have an impact, although not immediately apparent, potentially devastating. Nature, intended as a system, is the definition of survival, and, as skillfully described by Taleb [Taleb, 2012] in a world dominated by black swans, nature is antifragile. The key attributes of complex systems, biological systems fall into this category, which grant its antifragile properties are redundancy and decentralization. These two terms strongly clash with the business mentality oriented towards growth and profit, where efficiency and economy of scale are seen to be the north star. In this discussion, the problem of urban water management will be challenged with this approach. Starting from the technical definition of urban wastewater in the first chapter, a second section will follow explaining how cities have in the past and are today dealing with this issue, from adduction and distribution, through collection, to treatment and disposal. The third section consists of a future outlook in light of the rising demand in terms of both quantity and quality when facing a growing uncertainty and scarcity of the offer. The state of the art of decentralized water treatment technology in the fourth section will end up arranging all the pieces which will star in the comparative model developed and analyzed in the fifth section. The outline of the problem will attempt to reveal some black swans converting them to grey swans, and then the model will try to give robustness to tackle these and other uncertain scenarios. The red thread followed in the model, unrolls from the comparison between two key resources for our modern survival, water, and electricity. Given that these two worlds are closely related, and we cannot afford to lose either, we shall consider that power shortage would eventually result in a water shortage. Therefore, not building a robust power grid is not an option. On the other side water distribution infrastructure, as we will see in section two, requires significantly more physical space, ties up water resources in the cycle that could be implemented elsewhere, and relies on forecasts which inevitably lead to uncertainties finally resulting in inefficient use of economic resources.