The growing awareness of the need to improve water management has led to the development of the Water Footprint (WF) concept. Introduced by Hoekstra in 2002, WF is an indicator to assess the exploitation of water resources to realize products and services. There are many WF studies on agricultural products, few instead deal with industrial products and even fewer relate to waste. This case study analyzes the
WF of Granella®, an agglomerate obtained from the slag of the smelting furnace of a steel mill used in the production of bituminous pavements. First the WF of the process steps were analyzed, distinguishing between direct and indirect water uses.
Subsequently, the WF of all input materials were examined, paying particular attention to the evaluation of the energy used in the production of each single material.
The analysis shows that water consumption in each process step and for each material
considered is mainly due to electricity consumption, particularly high during the
melting phase from which steel and slag are obtained. The crucial aspect to define
Granella® WF is the method used for the allocation of water consumption to the two
co-products, steel and slag.
