A R30-million state-of-the-art water treatment plant at AECI Mining Explosives’ nitrates manufacturing facility in Modderfontein, in Johannesburg, is saving the city 400-million litres of potable water a year, which is enough for 4 624 people a year.

This is only the beginning according to AECI Water group executive Dean Mulqueeny, who is on a mission to move industry off the potable water grid as far as possible. The aim is to replace one-billion litres over the next five years.

“To get the ball rolling, we are working with other AECI Group businesses on water recycling projects, specifically in Chloorkop, Sasolburg and Umbogintwini where we have large-scale manufacturing operations. Test work is currently being done to enable front-end engineering design,” he says.

As far as the AECI Mining Explosives project is concerned, there were three water sources available:

• Process sewage effluent (PSE) water
• Effluent water from site run-off
• Cooling tower blowdown from the No. 9 and No. 11 Nitric Acid plants’ cooling towers

Since each source has different chemistry, different technologies were applied to ensure they were all treated properly and sustainably. A unique approach was designed and developed including three technology blocks, namely:

Dissolved Air Flotation (DAF)

DAF reduces precipitated phosphates and suspended solids.

Ultrafiltration (UF)

UF removes proteins, suspended solids and turbidity as well as most bacteria and some viruses. At AECI Mining Explosives, the three UF “trains” installed were aquasource, membrane and submerged systems.

Reverse Osmosis (RO)

RO removes dissolved ions and lowers the dissolved salt concentration. The treated water is then stored in a tank before being distributed to the cooling towers and demineralisation plant.

The benefits for AECI Mining Explosives include:

• Cost savings of about R11/m3
• Less potable water usage, alleviating pressure on the water network and enabling “business with purpose”
• Less wastewater discharged from site, leading to additional savings in operating expenses

This success story shows AECI’s collective commitment to shaping a better world in line with the global sustainability agenda.

This is One AECI, for a better world.