Water footprint and water pinch analysis techniques for sustainable water management in the brick-manufacturing industry

Brick-manufacturing is an intensive water-consuming industry that requires a sustainable and integrated water management strategy to reduce reliance on freshwater consumption. This study aims to develop a rigorous analytical tool based on water footprint principles and water pinch analysis techniques that can be used to manage and optimise water consumption. By performing thorough water audits, the water consumption footprint (the sum of blue and green water footprints) and the theoretical water pollution footprint (grey water footprint) were quantified. The total water consumption footprint of a brick is determined as 2.02 L, of which blue water is identified as 1.71 L (84.8%) and green water as 0.31 L (15.2%). The theoretical grey water footprint of a brick was found to be 1.3 L, a value that would have been higher if in-situ wastewater treatment had not been operated before effluent discharge. In order to reduce the water footprint of a brick, water pinch analysis techniques were applied for the brick-manufacturing processes. Two water recovery schemes were explored, i.e. direct re-use/recycle and water regeneration. For the former, water targeting was first carried out using the material recovery pinch diagram. Next, an algebraic technique was utilised for the targeting of water regeneration, where an interception unit is used to partially purify the water sources for further re-use/recycle. The network that fulfils the water flow rate targets was then designed using the nearest neighbour algorithm. The calculation indicates that direct re-use/recycle scheme reduces with the standard water consumption footprint reduced only by 15.6%. Water regeneration scheme, on the other hand improved the current value (which relies on an unsystematic water regeneration scheme) by 56.4%. The analysis clearly shows that the water consumption footprint of a brick is improved when the brick-manufacturing industry operates sustainable water management strategies. This study, a first of its kind, demonstrates that integration of water pinch analysis coupled with water footprint concepts, provides a robust and effective tool for the manufacturing industries that aim for sustainable water consumption. (C) 2017 Elsevier Ltd. All rights reserved.