Following its successful expansion of the sewage treatment plant at the Lucara Diamond’s Karowe Mine in Botswana, WEC Projects has secured further orders from the client. This time for the design and construction of a sedimentation trap, tanker filling station and associated infrastructure including storm drains and fencing.
About the Karowe Mine
Karowe Mine, where a 1174.76-carat high-quality white gem diamond, the third largest found in Botswana, was recently recovered, is located near the village of Letlhakane in the arid eastern Kalahari Basin where temperatures average 35°C. As a result, water is scarce, so much so that the Government of Botswana has imposed severe water restrictions on companies operating in the region. WEC Projects originally designed and built artificial wetlands which the mine uses to treat its effluent water, removing contaminants such as BOD, ammonia, suspended solids and heavy metals, to a standard for reuse as process water.
The Water Recycling Process
The new sedimentation trap will be used in the water recycling process of the mine’s drilling operations. The effluent is pumped from the underground drilling areas to a concrete trap and clarification unit where it is dosed with alum and a polymer to enhance the settling of the solids. The effluent overflows from the trap to the plant’s oil skimmer to remove floating oil. The system treats an average of 34 m3 of effluent per day but can be expanded up to 150 m3 per day if required.
The tanker station draws polished water after the artificial wetlands, which is dosed with chlorine to disinfect the treated effluent. The polished water is not used for human consumption but is stored for use in applications such as dust suppression.
Ruan Kellerman, WEC Projects Contracts Manager
“This project is a fairly standard one for WEC Projects, except for the wetlands section which was certainly the largest of its kind we have undertaken. Our clients, many of whom are located in some of the driest and hottest areas of Africa where water is scarce, rely on us to come up with agile solutions for water reuse and recycling. We can provide solutions capable of treating water to process water reuse standards all the way up to potable standards.”
