Water cost for water purification: Renewability assessment of a typical wastewater treatment plant in China

In the context of severe water shortage and water pollution, wastewater treatment plays an important role in recycling water resources and improving water quality. Renewability of the wastewater treatment system as reflected by the water cost for water purification is revealed by a case investigation of a typical wastewater treatment plant in China, by means of the tiered hybrid method combining process analysis and systems input-output analysis. Based on a normalized indicator of water investment in water purified, the industrial freshwater use for per cubic meter of treated wastewater is calculated as 0.0069 m³, demonstrating a high renewability of the case wastewater treatment plant. Tap water and electricity inputs are the main contributors to the industrial water use of the wastewater treatment system that respectively account for 46.4% and 23% of the total, while construction stage contributes a non-negligible proportion of 19%. Compared with previous findings, however, the water cost for water purification by the case wastewater treatment plant is obviously larger, which may be attributed to the adoption of a most comprehensive input inventory and the tiered hybrid method that could effectively incorporate both onsite and offsite water use. The outcome presents a unique perspective for evaluating the renewability of wastewater treatment plants and provides a reference for water conservation.