Pumps performing at wastewater plant

Since changing jobs from plumbing to managing a wastewater treatment facility, Wayne Brooking has kept similarities in his role; maintaining piping systems. Now he is responsible for the efficient processing of Kawerau’s wastewater on a much larger scale, and Watson-Marlow Bredel pumps are a key part of this process.

Kawerau District Council is possibly New Zealand’s smallest council entity and correspondingly the wastewater treatment plant is not very big - four settling hoppers and a small chemical room make up most of it. The facility, before being handed over to the council in 2007, used to also process waste pulp from the nearby SCA tissue plant. As the pulp is now bought in, it only made sense for the facility to be used solely for Kawerau’s wastewater treatment.

At the time of upgrade, Watson-Marlow Bredel pumps were selected by the consultant due to their ability to easily handle high solids concentration and dose accurately. The plant has four Bredel SPX pumps for thickener underflow transfer, a 520U electronic cased drive unit for concentrated anioic polymer dosing and a 520 close-coupled pump for concentrated cationic polymer.

In particular, Wayne was impressed with the peristaltic pumps’ ability to handle high concentration fluids. He noted, “This stuff (polymer) is nasty and thick and you don’t want to handle it unless you have to.”  Such a product would undoubtedly cake fluid path intrusions that are associated with other pump types. Peristaltic pumps operate on a simple principle, similar to how blood moves in our bodies; compressions to a hose or tube suck fluid in and push it forward.

Maintaining the plant is a busy job and installing Watson-Marlow Bredel pumps allow Wayne to focus on bigger plant issues such as fixing the centrifuge. The larger Bredel SPX pumps are installed with natural rubber hose and while their service is intermittent, the hoses last about 8 million compressions. The tubing in the dosing pumps also lasts a good distance, being quickly swapped out about every six months.