Country-level and gridded estimates of wastewater production, collection, treatment and reuse

Abstract

Abstract. Continually improving and affordable wastewater management provides opportunities for both pollution reduction and clean water supply augmentation, while simultaneously promoting sustainable development and supporting the transition to a circular economy. This study aims to provide the first comprehensive and consistent global outlook on the state of domestic and manufacturing wastewater production, collection, treatment and reuse. We use a data-driven approach, collating, cross-examining and standardising country-level wastewater data from online data resources. Where unavailable, data are estimated using multiple linear regression. Country-level wastewater data are subsequently downscaled and validated at 5 arcmin (∼10 km) resolution. This study estimates global wastewater production at 359.4×109 m3 yr−1, of which 63 % (225.6×109 m3 yr−1) is collected and 52 % (188.1×109 m3 yr−1) is treated. By extension, we estimate that 48 % of global wastewater production is released to the environment untreated, which is substantially lower than previous estimates of ∼80 %. An estimated 40.7×109 m3 yr−1 of treated wastewater is intentionally reused. Substantial differences in per capita wastewater production, collection and treatment are observed across different geographic regions and by level of economic development. For example, just over 16 % of the global population in high-income countries produces 41 % of global wastewater. Treated-wastewater reuse is particularly substantial in the Middle East and North Africa (15 %) and western Europe (16 %), while comprising just 5.8 % and 5.7 % of the global population, respectively. Our database serves as a reference for understanding the global wastewater status and for identifying hotspots where untreated wastewater is released to the environment, which are found particularly in South and Southeast Asia. Importantly, our results also serve as a baseline for evaluating progress towards many policy goals that are both directly and indirectly connected to wastewater management. Our spatially explicit results available at 5 arcmin resolution are well suited for supporting more detailed hydrological analyses such as water quality modelling and large-scale water resource assessments and can be accessed at https://doi.org/10.1594/PANGAEA.918731 (Jones et al., 2020).

Ecofriendly remediation technologies for wastewater contaminated with heavy metals with special focus on using water hyacinth and black tea wastes: a review

“…Huge amounts of contaminated wastewater are released into the environment due to population growth, urbanization, and industrialization (Rezania et al, 2015 ), approximately 359.4 × 10 9 m 3 year −1 (Jones et al, 2021 ). According to the United Nations, 80% of all industrial and urban wastewater in developing countries is released into the environment with no treatment (Joseph et al, 2019 ).…”

Precious Data from Tiny Samples: Revealing the Correlation Between Energy Content and the Chemical Oxygen Demand of Municipal Wastewater by Micro-Bomb Combustion Calorimetry

“…For extrapolating the annual worldwide chemical energy potential with the obtained Δ c H-COD correlation, further assumptions are required. Recently, it was estimated that the global wastewater production amounts to 369 billion m 3 y −1 (Jones et al, 2021). Assuming that all wastewater has a comparatively low COD (0.4 gCOD L −1 ), is treated, and that the energy extraction efficiency is 20 %, the global chemical energy potential of wastewater amounts to 1.2×10 5 GWh (see Supplementary Material S3 for details on calculations).…”

“…Obviously, these calculations included several uncertainties. For instance, substantial fractions of wastewater could have higher COD (especially industrial wastewaters), and at present, only 51% of the produced wastewater is also treated (Jones et al, 2021).…”

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

“…Globally produced domestic and municipal wastewater is estimated to amount to 360 km 3 year -1 , of which 41 km 3 year -1 (11.4%) is treated in wastewater treatment plants (WWTPs) and then re-used, 149 km 3 year -1 (41.4%) is treated in WWTPs and then discharged, and 170 km 3 year -1 (47.2%) is not treated in WWTPs but released directly to the environment (Jones et al, 2021). According to recent assessments, approximately 3.1 billion people worldwide had access to sewage systems connected to WWTPs in 2017 (WHO & UNICEF, 2017).…”

“…Also at the global scale, Jones et al (2021) recently produced a modeled, spatially disaggregated map of the amounts of wastewater production, collection, treatment and re-use. Besides estimating previously unavailable country-level wastewater statistics, the authors downscaled the country-level data to a 5 arc-minute resolution grid using return-flow data from the global hydrological model PCR-GLOBWB 2.…”