04 Aug 2021

04 Aug 2021

Review status: this preprint is currently under review for the journal ESSD.

Global distribution of wastewater treatment plants and their released effluents into rivers and streams

Heloisa Ehalt Macedo1, Bernhard Lehner1, Jim Nicell2, Günther Grill1, Jing Li2, Antonio Limtong1, and Ranish Shakya1 Heloisa Ehalt Macedo et al.
  • 1Department of Geography, McGill University, Montreal QC H3A 0B9, Canada
  • 2Department of Civil Engineering, McGill University, Montreal QC H3A 2K7, Canada

Abstract. The main objective of wastewater treatment plants (WWTPs) is to remove contaminants such as pathogens, nutrients, and organic and other pollutants from wastewaters using physical, biological and/or chemical processes prior to discharge into receiving waterbodies. However, since WWTPs cannot remove all contaminants, they inevitably represent concentrated point sources of residual contaminant loads into surface waters. To understand the severity and extent of the impact of wastewater discharges from such facilities into rivers and lakes, as well as to identify opportunities of improved management, detailed information about WWTPs is required, including (1) their explicit geospatial locations to identify the waterbodies affected; and (2) individual plant characteristics such as population served, flow rate of effluents, and level of treatment of processed wastewaters. These characteristics are especially important for contaminant fate models that are designed to assess the distribution of substances that are not typically included in environmental monitoring programs, such as contaminants of emerging concern. Although there are several regional datasets that provide information on WWTP locations and characteristics, data are still lacking at a global scale, especially in developing countries. Here we introduce HydroWASTE, a location-explicit global database of 58,502 WWTPs and their characteristics. This database was developed by combining national and regional datasets with auxiliary information to derive or complete missing WWTP characteristics, including the amount of people served. A high-resolution river network with streamflow estimates was used to georeference WWTP outfall locations and calculate each plant’s dilution factor (i.e., the ratio of the natural discharge of the receiving waterbody to the WWTP effluent discharge). The utility of this information was demonstrated in an assessment of the distribution of wastewaters at a global scale. Results show that 1.2 million kilometers of the global river network receive wastewater input from upstream WWTPs, of which more than 90,000 km are downstream of WWTPs that offer only primary treatment. Wastewater ratios originating from WWTPs exceed 10 % in over 72,000 km of rivers, mostly in areas of high population densities in Europe, USA, China, India, and South Africa. In addition, 2,533 plants show a dilution factor of less than 10, which represents a common threshold for environmental concern.

Heloisa Ehalt Macedo et al.

Status: open (until 30 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • EC1: 'Links for ESSD-2021-214', David Carlson, 04 Aug 2021 reply
  • CC1: 'Comment on essd-2021-214', Hilmi S. Salem, 25 Aug 2021 reply
  • RC1: 'Comment on essd-2021-214', Anonymous Referee #1, 03 Sep 2021 reply
  • RC2: 'Comment on essd-2021-214', Anonymous Referee #2, 11 Oct 2021 reply

Heloisa Ehalt Macedo et al.

Data sets

HydroWASTE Heloisa Ehalt Macedo, Bernhard Lehner, Jim Nicell, Günther Grill, Jing Li, Antonio Limtong, Ranish Shakya

Heloisa Ehalt Macedo et al.


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Short summary
We introduce HydroWASTE, a location-explicit global database of 58,502 wastewater treatment plants (WWTPs) and their characteristics to understand the impact of discharges from such facilities. HydroWASTE was developed compiling regional datasets and using auxiliary information to complete missing characteristics. The location of the outfall of the WWTPs into the river system is also included, allowing the identification of the waterbodies most likely affected.