WEC Projects, with an undisclosed joint venture (JV) partner, has designed and built a new water treatment plant to supply potable water to one of the most populous communities in Gauteng.
The R270-million plant, in partnership with a local construction, concessions and manufacturing group, has been designed to provide 60 Ml a day and was commissioned as part of a R1-billion upgrade project for a community that has been experiencing a considerable increase in demand for potable water over the last few years.
The scope of work for WEC Projects included the mechanical, electrical and instrumentation work.
While the contract to expand the existing facility, including the mechanical, electrical and control scope, was awarded to WEC Projects and its JV partner in 2016, the complexity of the project and the need for buy-in from the local communities benefiting from the treatment plant meant final commissioning only took place in 2021.
“This project certainly rates as one of the most challenging that we have undertaken. The design of the plant required the water to undergo a complex processing solution in order to achieve the quality level required by the local municipality,” said WEC Projects MD Wayne Taljaard.
“We were also required to integrate the new plant module into the existing treatment plant. As a result the plant integrates a sophisticated and advanced control and instrumentation system to ensure consistent quality and plant uptime.”
While the requirements were for a water treatment plant capable of delivering 60 Ml a day, the new plant has been tested successfully to 120 Ml a day, ensuring that it will be able to handle increased demands in the future.
The company explained that raw water is drawn from a nearby dam and pumped to the facility where it initially undergoes clarification to remove suspended solids, before undergoing dissolved air flotation to remove any remaining solids and oils.
The clarified water then enters a rapid gravity sand filtration system to remove particles.
“This type of filtration system was specified owing to the higher filtration rate it provides compared with conventional sand filters, a necessity for a plant that is required to supply more than 500 000 people,” he said.
After exiting the sand filter the water is pumped to the ozonation facility for rapid oxidation and disinfection, followed by a second filtration process through a filter system containing granular activated carbon.
This process removes organic chemicals and other similar impurities. The final process sees the chlorification of the water to ensure that any harmful impurities such as bacteria are removed.