Wastewater Reclamation for Potable Supply
Summary
In the 1960s, Windhoek, Namibia, became the first city to turn wastewater into potable drinking water.
Before the mid-twentieth century, Windhoek, Namibia, relied on local springs as its primary water source, but as the city grew, these springs could no longer meet the growing population's water demand. Underscoring this challenge, Namibia is known as the 'driest country south of the Sahara Desert', and 97% of its rainfall evaporates (Scott et al., 2018). Thus, rainwater harvesting and other such methods are ineffective options for augmenting the city's water supply.
Throughout the twentieth century, a growing population, declining rainfall patterns, increasing evapotranspiration, and other such obstacles pushed Windhoek's local water utility to seek alternative sources of water, and the city took innovative measures in the 1960s to ensure its future water security (Onyango et al., 2014). In 1968, the City of Windhoek (CoW) launched the first wastewater reuse facility that transformed wastewater into potable water.
Intervention
Windhoek's municipality turned to recycled water to avoid extreme water shortages and ensure its population had a consistent fresh water supply. In 1968, the city built the Goreangab Wastewater Reclamation Plant, thereby becoming the first city to turn wastewater into drinking water. After lengthy pilot testing (1960?1968), secondary treated effluent was reclaimed, blended with dam water, and directly added to the city's supply to meet up to 12% of the daily demand. On November 24, 1968, Windhoek began drinking treated sewage water (du Pisani & Menge, 2013).
By 1995, Windhoek's annual growth rate was 6-8%, and the city was once more in a position where it could not provide enough water. The city researched the potential for expanding the reclamation plant, but ultimately decided on developing a new plant to cope with the growing population and increasing water demand. In 2001 - in collaboration with Veolia, Berlinwasser International, and WABAG - the New Goreangab Plant was developed and became operational in 2002. The EU investment bank, CoW, and Kreditanstalt fuer Wiederaufbau sponsored this new plant's design and construction (Onyango et al., 2014). Today, citizens take pride in this innovative method, and the original plant is now used to reclaim water for irrigation and other non-potable uses.
The Windhoek Goreangab Operating Company (WINGOC), a consortium of global water operator Veolia, operates the New Goreangab Plant. The plant uses a multiple-barrier system to minimize contamination and protect public health. These barriers include treatment, non-treatment, and operational barriers (see Appendix for the full process).
Today, through this process, the Goreangab plant provides 21,000 m3 of water per day. Depending on seasonal demand, between 35-50% of Goreangab water is used to augment surface water supplies or aquifer recharge. (Onyango et al., 2014; Wingoc, n.d.).
Before the initial opening of the Goreangab plant, the CoW knew that it was imperative to engage and educate its citizens on the need for and process of using treated wastewater. The city's educational campaigns include school tours of the plant (for primary and secondary schools and universities), science fair projects focused on water, and ongoing engagement through municipal newsletters (Onyango et al., 2014).
Challenges
Despite the advantages of utilizing wastewater reclamation, the initial investment for appropriate infrastructure can be costly (Asano & Bahri, 2011). Additionally, it is essential to maintain a strong workforce for the reclamation plant to ensure its maintenance and stability.
Outcomes
Since its commissioning in 2002, the new plant satisfies 35% of the city's and its suburbs' drinking water needs, supplying nearly 300,000 people with 21,000 m3 of water per day (Onyango et al., 2014). Water reclamation in Windhoek has persisted through multiple political regime changes and continues to be a vital source of the water supply. Additionally, no adverse health effects have been detected since the plant's inception in 1968. A ten-year epidemiological study concluded that the reused water was safe for consumption based on bacteriological and virological water quality results; water reuse did not increase incidences of diarrheal disease from water-borne pathogens (Onyango et al., 2014). Maintaining health and safety within the plant is paramount, and the CoW understands that any public health adverse event related to the plant has the potential to ruin the framework of trust established over the past 40 years.
References
Wastewater Reclamation for Potable Supply
Summary
In the 1960s, Windhoek, Namibia, became the first city to turn wastewater into potable drinking water.
Before the mid-twentieth century, Windhoek, Namibia, relied on local springs as its primary water source, but as the city grew, these springs could no longer meet the growing population's water demand. Underscoring this challenge, Namibia is known as the 'driest country south of the Sahara Desert', and 97% of its rainfall evaporates (Scott et al., 2018). Thus, rainwater harvesting and other such methods are ineffective options for augmenting the city's water supply.
Throughout the twentieth century, a growing population, declining rainfall patterns, increasing evapotranspiration, and other such obstacles pushed Windhoek's local water utility to seek alternative sources of water, and the city took innovative measures in the 1960s to ensure its future water security (Onyango et al., 2014). In 1968, the City of Windhoek (CoW) launched the first wastewater reuse facility that transformed wastewater into potable water.
Issue
Intervention
Windhoek's municipality turned to recycled water to avoid extreme water shortages and ensure its population had a consistent fresh water supply. In 1968, the city built the Goreangab Wastewater Reclamation Plant, thereby becoming the first city to turn wastewater into drinking water. After lengthy pilot testing (1960?1968), secondary treated effluent was reclaimed, blended with dam water, and directly added to the city's supply to meet up to 12% of the daily demand. On November 24, 1968, Windhoek began drinking treated sewage water (du Pisani & Menge, 2013).
By 1995, Windhoek's annual growth rate was 6-8%, and the city was once more in a position where it could not provide enough water. The city researched the potential for expanding the reclamation plant, but ultimately decided on developing a new plant to cope with the growing population and increasing water demand. In 2001 - in collaboration with Veolia, Berlinwasser International, and WABAG - the New Goreangab Plant was developed and became operational in 2002. The EU investment bank, CoW, and Kreditanstalt fuer Wiederaufbau sponsored this new plant's design and construction (Onyango et al., 2014). Today, citizens take pride in this innovative method, and the original plant is now used to reclaim water for irrigation and other non-potable uses.
The Windhoek Goreangab Operating Company (WINGOC), a consortium of global water operator Veolia, operates the New Goreangab Plant. The plant uses a multiple-barrier system to minimize contamination and protect public health. These barriers include treatment, non-treatment, and operational barriers (see Appendix for the full process).
Today, through this process, the Goreangab plant provides 21,000 m3 of water per day. Depending on seasonal demand, between 35-50% of Goreangab water is used to augment surface water supplies or aquifer recharge. (Onyango et al., 2014; Wingoc, n.d.).
Before the initial opening of the Goreangab plant, the CoW knew that it was imperative to engage and educate its citizens on the need for and process of using treated wastewater. The city's educational campaigns include school tours of the plant (for primary and secondary schools and universities), science fair projects focused on water, and ongoing engagement through municipal newsletters (Onyango et al., 2014).
Challenges
Despite the advantages of utilizing wastewater reclamation, the initial investment for appropriate infrastructure can be costly (Asano & Bahri, 2011). Additionally, it is essential to maintain a strong workforce for the reclamation plant to ensure its maintenance and stability.
Outcomes
Since its commissioning in 2002, the new plant satisfies 35% of the city's and its suburbs' drinking water needs, supplying nearly 300,000 people with 21,000 m3 of water per day (Onyango et al., 2014). Water reclamation in Windhoek has persisted through multiple political regime changes and continues to be a vital source of the water supply. Additionally, no adverse health effects have been detected since the plant's inception in 1968. A ten-year epidemiological study concluded that the reused water was safe for consumption based on bacteriological and virological water quality results; water reuse did not increase incidences of diarrheal disease from water-borne pathogens (Onyango et al., 2014). Maintaining health and safety within the plant is paramount, and the CoW understands that any public health adverse event related to the plant has the potential to ruin the framework of trust established over the past 40 years.
Issues |
|---|
Water Scarcity and Access |
Solutions |
|---|
Alternative Water Sources & Resource Diversification |
References
Asano, T., & Bahri, A. (2011). Global challenges to wastewater reclamation and reuse. On Water Front, 2, 64–72.
du Pisani, P., & Menge, J. G. (2013). Direct potable reclamation in Windhoek: A critical review of the design philosophy of new Goreangab drinking water reclamation plant. Water Supply, 13(2), 214–226. https://doi.org/10.2166/ws.2013.009
Haarhoff, J., & Van der Merwe, B. (1996). Twenty-five years of wastewater reclamation in Windhoek, Namibia. Water Science and Technology, 33(10), 25–35. https://doi.org/10.1016/0273-1223(96)00403-9
Menge, Jürgen. (2010). Treatment of Wastewater for re-use in the Drinking water system of Windhoek.
Namibia: Windhoek has been producing drinking water from its wastewater for 50 years. (n.d.). Veolia. Retrieved September 15, 2020, from https://www.veolia.com/en/newsroom/news/drinking-water-recycling-wastewater-windhoek-namibia
Onyango, L., Leslie, G., & Wood, J. G. (2014). Project Report Global Potable Reuse Case Study 4: Windhoek, Namibia. Australian Water Recycling Centre of Excellence. http://vuir.vu.edu.au/32234/1/WQ%2BCase%2BStudy%2B4%2B-%2BWindhoek%2BNamibia%2B100815.pdf
PRI. (2016). Recycling sewage into drinking water is no big deal. They’ve been doing it in Namibia for 50 years. (n.d.). The World from PRX. Retrieved September 17, 2020, from https://www.pri.org/stories/2016-12-15/recycling-sewage-drinking-water-no-big-deal-theyve-been-doing-it-namibia-50-years
Scott, D., Iipinge, K. N., Mfune, J. K. E., Muchadenyika, D., Makuti, O. V., & Ziervogel, G. (2018). The Story of Water in Windhoek: A Narrative Approach to Interpreting a Transdisciplinary Process. Water, 10(10), 1366. https://doi.org/10.3390/w10101366
van Rensburg, P. (2016). Overcoming global water reuse barriers: The Windhoek experience. International Journal of Water Resources Development, 32(4), 622–636. https://doi.org/10.1080/07900627.2015.1129319
Veolia. (2016, January 19). In Windhoek, there’s no water but there are ideas. Living Circular. https://www.livingcircular.veolia.com/en/industry/windhoek-theres-no-water-there-are-ideas
Wingoc. Our history. (n.d.). Wingoc. Retrieved September 21, 2020, from https://www.wingoc.com.na/our-history