MechChem Africa March-April 2022

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Local water and wastewater treatment EPC contractor,WEC Projects, along with mineral processing plant specialist, Multotec, have joined forces to develop a customised modular solution to remove toxic arsenic from the wastewater of a mine in Mali, West Africa. Wayne Taljaard, managing director of WEC Projects reveals more. Modular wastewater plants ideal for African Mines W EC Projects, in conjunction with its partner Multotec, has designed and custom engineered a wastewater wastewater to themine’sdischargestandards,” he says.

able energy, water reuse, resource recovery, sludge beneficiation and zero liquid discharge. “Our ability to provide a customised and modularsolutionforMultotecunderscoresour ability as amajor player in the industry, both in South Africa as well as across the continent,” Taljaard concludes. www.wecprojects.com

WEC has completed projects in South Africa, in 24 African countries and as far afield as Eritrea, Oman and Australia. The company offers innovative turnkey solutions designed tomeet client requirements including environ- mentallycompatiblesolutionsrequiringrenew-

treatment plant for a goldmine inMali, West Africa. Theplant, used to remove arsenic from the mine’s wastewater stream, incorporates a modular design which simplifies the logis - tics and reduces the costs of transport and installation. The international mine operator is a client of Multotec, a local engineering company spe- cialising inmineral processing plant design and installation. The company approached WEC Projects, a local EPC contractor in the water and wastewater treatment industry, to jointly develop a customised solution to remove toxic arsenic from the mine’s wastewater. A multi- stage removal system was required to meet the strict standards for the mine’s discharge. However, the system also required a modular design to simplify transportation, installation and commissioning of the plant. Says Wayne Taljaard, managing director of WEC Projects: “The mining industry in Africa presents some unique challenges, not the least of which are the remote locations of many of theminingsitesandthedifficultiesexperienced in getting staff and equipment to places where road, power and water infrastructure is often lacking.HencetherequirementbyMultotecfor a modular solution that would allow for rapid transport to site and simpler installation and commissioning. “The COVID-19 pandemic added to the difficulties for us and the client, causing delays that reduced the time frame for delivery,” Taljaard adds. In the treatment process, themine’s waste- water undergoes primary solid/water sepa- ration using coagulation and flocculation in the primary clarifier. From there it enters a two-stage chemical precipitation and second- ary clarification process to reduce the arsenic levels. The final stage sees the sludge undergo dewateringbeforedisposal. The treatedwater, althoughnotpotable, isthenreusedbythemine as process water. The plant has a processing capacity of 150 m 3 /h and is capable of reducing the arsenic levelsfromaround13mg/ ℓ tolessthan0.1mg/ ℓ . “The project incorporates a number of unique features in addition to its modular design, including nine custom-designed, pro- prietary lamella clarifiers and a multi-stage arsenicremoval processcapableof treatingthe

A 3D model of the modular wastewater treatment plant designed to remove arsenic from the mine’s wastewater stream.

WEC Projects custom-engineered a modular wastewater treatment plant for a gold mine in Mali, West Africa.

44 ¦ MechChem Africa • March-April 2022