Urban Mining for a Circular Economy

Abstract

Inherently related to the quadrupling of global population and the 20-fold increase of global economic output in the last century, is the increase of inputs of raw materials and energy into society and its corresponding outflows. In order to lower the volume of outflows and effectively control pollution, a reduction of raw material use throughout the economy is required. A shift from a linear to a circular economy plays an important role in achieving global climate goals. In a circular economy materials are kept in use for as long as possible so that the need for virgin materials is as little as possible. From a perspective of a circular economy material stocks in urban areas can be considered as ‘natural resources’. These in-use stocks can be described as the urban mine, a concept that is defined as the systematic reuse of anthropogenic materials from urban areas such as buildings and infrastructure for example. Although using the urban mine is desirable, knowledge about stocks and flows of the potential urban mines is limited. One of the infrastructure stocks that has not been assessed yet is the infrastructure of the urban water cycle in the Netherlands. The Dutch urban water cycle as assessed in this study consists of the drinking water production sites and supply network as managed by the 10 drinking water companies, the sewage network, gully pots and a large part of the sewage pumping stations as managed by the municipalities, and some of the sewage pumping stations, transportation pipelines and wastewater treatment plants as managed by the 21 water boards in the Netherlands. In order to analyse the urban mine of the Dutch urban water cycle infrastructure, stock data was gathered about the current size and historic development of the different components of the urban water cycle infrastructure. Per component, the material composition and share is determined to calculate the total material stocks of the urban water cycle between 1950 and 2020…