Overall, the company sees an increasing drive from industry to do more wastewater treatment in less space, reduce waste disposal costs and extract value in the form of water reuse and energy. "We are working to make our oxygen technologies more efficient and, with partners, are developing complete treatment systems designed to take advantage of the benefits of oxygen," he says.
At its Rotterdam site in the Netherlands, Akzo Nobel has cut fresh water consumption while increasing the concentration of saline water that its treatment plant can handle. Salt concentration has risen from its original maximum concentration of 2% as process intensification and expansion projects took place.
"Our first choice, an anaerobic biological system, did not work. But we found we could use an aerobic system instead. By slowly creating and maintaining a biomass that was adjusted to the higher salt concentrations, we were able to operate at 3% salts. Large water savings were realized and we could operate the installation at a higher total capacity," notes a spokeswoman.
At its Delfzijl, the Netherlands, site, Akzo has installed an efficient co-generation plant to generate steam for a multi-effect evaporation process, with condensate purified and reused in a continuous recycling system.
Half a world away, the BP refinery in Kwinana, Australia, (Figure 3) now sends its wastewater to a water recycling plant instead of discharging it into the Cockburn Sound. In addition, the company is taking in treated sewage water from a nearby effluent plant. This water, treated by intense microfiltration and RO, is so pure that it would leach metal from standard piping. So BP has installed glass-reinforced epoxy pipelines.
Seán Ottewell is Chemical Processing's Editor at Large. You can e-mail him at firstname.lastname@example.org.