The pollutant removal of wastewater treatment has been facing the challenge of increasing energy consumption and varying spatial heterogeneity in China. This paper first employed an input-output (IO) model to calculate the sectoral wastewater pollutant (COD) discharge coefficients and a multi-regional input-output (MRIO) model was employed to explore the provincial virtual wastewater pollutant (COD) flows in China. Then, the energy efficiencies of wastewater treatment plants (WWTPs) in different provinces were inventoried. This study developed an assessment framework combining the multi-regional input-output model, virtual pollutant, and embodied energy. The critical pollutant discharge sectors (Service, Agriculture, Textile industry, Food and tobacco processing, Manufacture of chemical products, Production and distribution of tap water) and provinces (Shandong, Jiangsu, Guangdong, Henan, Zhejiang, Hubei, Sichuan) were identified. It was found that the pattern of virtual wastewater pollutant flows in China was efficient in energy saving. Majority of virtual wastewater COD (wwCOD) was transferred from higher energy efficient provinces to lower energy efficient provinces for saving 1.6×107 kW.h electricity. The study may help optimize the spatial regulation of national energy conservation and pollution reduction.
Keywords Pollutant transfer, energy saving, COD, multi-regional input-output analysis