MechChem Africa November-December 2022

Geotextile dewatering bags: the emergency solution for dewatering and solid waste management

MechChem Africa visited the ZebraTube stand at Electra Mining Africa and talked to Tshepang Dolamo, the company’s technical sales engineer, about the significant difference ZebraTube geotextile dewatering tubes and bags can make in preventing sewage and mine-impacted wastewater from contaminating freshwater ecosystems.

W ith a Bachelor of Technology degree in chemical engineer ing from the University of Johannesburg, Tshepang Dolamo began her career as a water treat ment process engineer on the goldmines in the Carletonville area. “I have a background as a process engineer looking after the plants treating mine-impacted water to potable or environmental discharge quality levels,” she tells MechChem Africa. “I worked on a Crystalactor ® plant with a treatment capacity of 5.0 M ℓ per day for removing hardness ions and heavy metals, including uranium and arsenic, for example. The system consists of a vessel filled with small sand pebbles. The contaminated mine water is dosed with chemicals that trigger precipitation and introduced from the sides of the vessel. The heavy metals come out of solutionandattach themselves to thepebbles, while near potable water is taken off the top. The only thing other thing we had to adjust was the pH, adding a little acid if the pH was

too high or alkaline chemicals if we needed to increase the pH,” Dolamo explains. “We also ran a dual-stage ion exchange plant, which was able to remove water hard ness elements using ion exchange resins to produce potable water,” she says, adding that she was involved in managing a 40 M ℓ /day settler plant in the Carletonville area. Dolamo resigned fromher job as a process engineer to join ZebraTube because she felt her skills and personality were better suited to technical sales. “With my background in water treatment, I thought I could add more value to the wastewater sector if I were out talking to people and helping them to imple ment newprojects. So, I amnow the technical sales engineer for ZebraTube, out in the field looking for opportunities touseour geotextile tubes and bags to help people better meet theirdewateringneeds andmanage their solid waste,” she informs MechChem Africa . Describing a more unusual project on the West Coast, Dolamo says that ZebraTube has supplied large low-flow tubular geotextile

bags to a diamond processing plant close to the shore. “We put our tubes along the beach front at lowtide andwent as far aswepossibly could, effectively building a berm wall to en able the processing plant to be moved closer to the shore,” she says. To fill the bags, sea sandwas pumped from 50 to 100moffshore using slurry pumps. The water immediatelybegins todrainout, leaving behind a very efficient retaining wall about 1.8 m high to keep the Cape’s stormy seas at bay. Acore focus for ZebraTube inSouthAfrica, though, is for emergency dewatering applica tions for mine impacted water or municipal wastewater. “Wehave started toassistwaste water plants along theVaal River. For example, aclient inSebokeng isfilling sixof ourhighflow tubes every month to reduce the amount of effluent overflow entering the Vaal river,” she tells MechChem Africa.

The desludging of Diepsloot Northern Wastewater treatment works.

6 ¦ MechChem Africa • November-December 2022