Life Cycle Assessment Of Treated Water Reuse Systems In Industrial Parks

The rapid development of industrial parks in China caused large resource consumption and pollutant emissions, especially freshwater usage and wastewater discharge, which constraint the sustainable development of industrial parks in China. Treated water reuse has attracted much attention from governments because of its potential to conserve freshwater and reduce pollutant emissions. However, treated water reuse usually means adding advanced treatment which consumes chemicals, materials and energy. Is the treated water reuse beneficial for the environment from a life cycle perspective?The objective of this study was to quantify the environmental impacts of reusing treated wastewater of a typical industrial park in China under different scenarios through a comparative life-cycle assessment (LCA). The reverse osmosis and electrodeionization process were applied as the wastewater tertiary treatment. Four scenarios are assessed:wastewater is treated and discharged,20%and99%of wastewater is treated and reused as industrial process water, and99%treated wastewater is used for horticulture. Inventory data were mainly obtained from a facility which manages the wastewater treatment and reuse system. Environmental impacts were evaluated using the CML2001method built into the GaBi version4.3database.The results show that marine aquatic toxicity potential (MAETP) is the most significant impact category related to the water reuse system, while abiotic depletion potential (ADP), acidification potential (AP), eutrophication potential (EP), fresh water aquatic ecotoxicity potential (FAETP), global warming potential (GWP), human toxicity potential (HTP), terrestrial ecotoxicity potential (TETP) and photochemical oxidation potential (POCP) are also major impact categories. Chemical production mainly contributes to the ADP. EP and FAETP highly depend on the pollutants contained in the wastewater discharged. The key contributor to other environmental impacts is energy consumption.Unlike municipal water reuse systems, the tertiary treatment for industrial water reuse greatly increases the environmental impacts of the system; however, it can be offset because of the larger credit from avoiding traditional production of industrial deionized water. The scenario with higher water recycling rate(99%) results in the lower environmental impacts. In summary, water reuse in an industrial park is beneficial from the environmental perspective.Different applications of reclaimed water affect the environmental performance of the system, which implicates that tertiary treatment should match with the reuse purpose. The results of the system life cycle cost of the operation phase show that the operation cost of water reuse project is higher than the traditional wastewater treatment system, emphasizing the importance of the pricing of the reclaimed water and a good market mechanism.Decision makers are recommended to take water demand, local water resource, water quality and environmental impact into consideration in the water management at an industrial park, and reuse as much wastewater as possible for the proper application. Using renewable energy and waste heat from the power plant can improve the environmental performance of the system, and alternatives to better dispose the sludge can be adopted.