Eco-efficiency of water and wastewater management in food production: A case study from a large dairy in Denmark

Rising water demands and pressures on water resources call for water management in industrial production. An eco-efficiency framework may provide justification for water consumption and treatment by combining environmental and economic dimensions in a life cycle perspective. We used principles of value added and value chain assessment (VCA) in the life-cycle system boundaries for a consistent assessment of eco-efficiency. The method was demonstrated for a membrane bioreactor-based, decentralized wastewater treatment and reuse in a dairy. The LCA results showed that decentralized wastewater treatment and reuse in the dairy will improve the aquatic environment by 80% (freshwater) and 51% (marine water), but increase the negative impact on climate change by 27% compared to conventional wastewater treatment. The VCA revealed that the decentralized alternatives would increase the value added by 1.3-1.4 euro/m(3) wastewater in the dairy, but also incur a value loss of 1.4-1.9 euro/m(3) for associated stakeholders such as the centralized wastewater treatment plant. The case study revealed the critical nature of a well-defined system boundary that includes impacts along the entire value chain and exposed pros and cons for decision-makers at both the system level and individual stakeholder level.