Cross-media transfer footprint control for sustainable environment management - a perspective from wastewater...

Current policy and technology development for pollutants removal are mostly dedicated to improving the efficiency of pollutants removal from one medium, rather than reducing the simultaneous impact on other environmental media. Here, we introduce cross-media transfer footprint (CMTF), a new environmental footprint (EF) metric, to reveal and quantify the environmental impacts of pollutants transferred across media. As an illustrative example, we assess the spatio-temporal trajectories of carbon (C), nitrogen (N), and phosphorus (P) CMTF during wastewater treatment plant (WWTP) operations across China for the period 2014-2019. The results indicate that, in 2019, wastewater treatment in China directly or indirectly resulted in the transfer of 7163 kt of C and 1018 kt of N to the atmosphere, as well as 3092 kt of C, 562 kt of N, and 228 kt of P to sediments. These processes led to an increase of 4.9 × 10⁹ EUR in CMTF towards the atmosphere and sediments (as calculated in Impact World+ after normalization and weighting of various environmental impacts). In 2014-2019, the growth in population and wastewater per capita were dominant drivers for increasing CMTF of C, N, and P, contributing to an increase of 693 million EUR (MEUR) (36 %), 359 MEUR (35 %), and 2.3 MEUR (44 %), respectively. With resource-oriented technological transformation, the CMTF of WWTPs have potential to decrease 86 % by 2050, compared with 20 % under the baseline scenario. We suggest a shift from single-media EF management by every isolated sector to more sustainable multi-media integrated approaches involving inter-sector collaboration.