Towards water resource factories

Abstract

In the current linear take-make-waste pattern the production of goods starts with raw material extraction followed by industrial conversion into products that are used and finally wasted. This linear system accelerates resource depletion and therefore hinders the development of sustainable societies. This is also valid for the use of water and the implied production of wastewater. The ongoing rapid urbanisation in many areas of the world including Europe has led to high increases in wastewater since the beginning of the 20th century. The initial goal of wastewater treatment was to protect surface water users from health risks due to pollution. Then, during the last decades the protection of the environment itself from nutrient pollution has been enforced by implementing stricter legal wastewater treatment plant (WWTP) effluent standards. The conventional activated sludge process is the currently most widely applied wastewater treatment technology in these plants. It succeeds in reaching legal standards for chemical oxygen demand (COD), nitrogen, and phosphorous effluent concentrations but in its currently applied form, it is considered unsustainable due to its low resource recovery potential and cost-effectiveness on the one hand and its high energy demand and environmental footprint on the other. To adapt wastewater treatment practices to urgent requirements for more sustainable urban environments, a paradigm shift has been proposed by academia since over a decade. It recognises the potential of wastewater as a resource and demands to perceive it as such instead of a waste stream....