The City of Windhoek runs three wastewater treatment plants: two plants treat domestic sanitary sewer and one plant is exclusively for industrial effluent. Unlike in Cincinnati, here industrial wastewater is treated separately because the effluent from domestic wastewater is reclaimed for drinking water.
You may remeber from my earlier posts that Windhoek is the only city in the world that directly augments its drinking water supplies with reclaimed water from sewage water. Just like most Americans would be, I was frightened (and intrigued at the same time) at the thought of drinking reclaimed sewer water. So I contacted NamWater (the drinking water people) and the City of Windhoek that owns all of the City’s wastewater plants, through my host, the Polytechnic of Namibia. NamWater is owned by the Government of Namibia, which owns every drop of water in the country, whether on the ground, underground, or in the wastewater treatment plant. I was interested in learning more about the Gammams wastewater treatment plant, as the effluent from Gammams serves as the raw water for the Goreangab reclamation plant. At the Goreangab plant, the water is purified to exceed the US EPA’s drinking water standards before it is blended with drinking water. Talk about a complete water cycle!
Both plants I toured (Gammams and Goreangab), are run to meet international standards. The Gammams wastewater treatment plant is also used to harvest methane gas (this gas is naturally produced during wastewater treatment) to run its own small power generator and meet its electricity demand. But I was most intrigued by the water reclamation plant. I saw effluent flowing out of Gammams wastewater plant into a natural reservoir (maturation ponds) from where it is picked by the Goreangab reclamation plant. Ozone gas is used at least at two times during the process to kill any living organisms and chlorine is also used at least at two steps to sanitize water. During the final step, the water is filtered through a series of extremely fine filters which can remove even residual viruses. The whole process of purification is meticulous and quite impressive. The end product is extremely safe and exceeds drinking water standards. The plant manager proved it by drinking it in front of me (see the picture below).
Some pictures from my trip to Gammams wastewater treatment plant and Goreangab Reclamation Plant are below. Please feel free to send me any questions or comments.
Some wildlife pictures are coming soon!
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| Gammams Wastewater Treatment Plant |
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| Wastewater coming into the plant |
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| Methane gas collection tank |
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Wastewater is aerated twice at the Gammams plant. The above picture is of the second aeration process which is much vigorous than the regular aeration process (as done at our MSDGC plants). The second aeration of wastewater is done to inject as much oxygen as possible in the water. After this heavy aeration of sludge water, the solids are separated and effluent is released into the maturation reservoir (pictured below). Because the effluent is going to be purified and mixed with drinking water, it must have high dissolved oxygen contents to meet the standards.
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| Water maturation reservoir. Effluent from the Gammams WW plant flows into this reservoir where remaining solids and other contaminants are removed naturally. This water slowly flows towards the Goreangab Reclamation Plant. The reservoir water sustains aquatic life (fish), an indication that the water has enough dissolved oxygen. |
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| Effluent, "matured raw water" from the reservoir arriving at the Goreangab Reclamation Plant. It takes about 4 days for the water to arrive to this plant after being released in the reservoir by the Gammams plant. |
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| Final filtration step. A series of extremely fine filters are used in a series to remove any viruses and other biological material that might have survived two doses of ozone followed by chlorine treatments and managed to reach to this point. |
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| Inside look of a filter. |
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| If I can drink it, you can too. Plant Manager, Mr. John Esterhuisen, is demonstrating his confidence in the water purification process by collecting a purified sample and drinking in front of me. (No, I still couldn't find the courage to follow his lead). |
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| From wastewater to drinking water. The sample on the left is what comes in the reclamation and purification plant from the maturation reservoir and what goes out after purification (sample on right). You can see the difference. |
And finally, a tangled tree at the Gammams WWT Plant
