Sustainable Asset Valuation of Wastewater Treatment Infrastructure in South Africa

An integrated assessment of infrastructure solutions for reducing nutrient-related pressures in the Hartenbos estuary

This report presents the results of a Sustainable Asset Valuation (SAVi) assessment for wastewater treatment infrastructure in South Africa. Specifically, the study analyzes different wastewater treatment options for improving water quality in the Hartenbos estuary. It also explores opportunities for reusing water for irrigation and related impacts on nutrient loads to the estuary.
By Georg Pallaske, Andrea Bassi, Ronja Bechauf, Liesbeth Casier, Matthew Gouett, David Uzsoki on May 17, 2022
  • Recycling treated wastewater for irrigation offers considerable benefits for climate adaptation and the agriculture sector. Reusing 50% of the water by 2060 would cover the water demand of 330 additional hectares of agricultural land, resulting in higher water security, agricultural productivity, and job creation.

  • The economic viability of the wetland option depends on whether its implementation increases habitat quality and biodiversity, which in turn attracts additional tourists relative to the baseline. Practically, when ecological and tourism benefits are considered, the wetland is the most economical option; when these are excluded, it is the least economical option.

  • The results of the analysis illustrate that planners and policy-makers need to carefully consider the benefits and trade-offs of different infrastructure options for wastewater treatment. While the hybrid solution performs best for reducing nutrient pollution, the potential to create additional revenues from tourism through the implementation of the artificial wetland would result in even higher net benefits relative to the hybrid option.

The results of this assessment provide an overview of the societal costs and benefits of different water treatment options, considering outcomes for citizens, businesses, Mossel Bay Municipality, and the Western Cape Government. The comparative valuation provides several insights. Examples of research questions include: how efficient are the different technologies for treating the wastewater, and what contribution would they provide to the water quality of the Hartenbos estuary? Do the different options comply with national water quality standards? What would be the direct and indirect economic outcomes of improving water quality and recycling water? These questions (and more) are answered in this SAVi assessment.