Fine screen technology simplifies wastewater treatment

Wastewater fine screen technology is designed to curtail blockages, spills and their associated maintenance and safety issues in municipal and industrial wastewater treatment plant (WWTP) applications.

To simplify fine screening processes, CST Wastewater Solutions has engineered horizontal in-channel rotary drum screening technology. The in-channel, low-maintenance, stainless steel design — with low fluid head loss at peak flows for increased solids removal efficiency — is used on wastewater flows and is custom-engineered for conditions in Australia and New Zealand.

“Advantages of this technology when dealing with fine screening of larger flows (5 mm or finer screening on flows up to 2000 L/s flow) include mechanical simplicity, self-cleaning and high-efficiency screening for reduced maintenance and cheaper whole-of-life costs compared with other types of screens, such as band and inclined drum screen designs,” said CST Wastewater Solutions Managing Director Michael Bambridge.

Key to functionality is the configuration of the design — the screening drum is installed horizontally semi-submerged in line with the incoming wastewater. The plate at the back of the drum directs flow radially through the mesh to optimise solids separation and self-cleaning.

An internal hopper collects the screenings, which are flumed out to the integral lifting and dewatering screw, to efficiently dewater and reduce screenings volume. The lifting screw is shaftless to avoid any blockages, even in the presence of long rags and fibrous products, and includes screen and screening washing. Lifting and screenings handling can also be conducted outside the channel, which increases options for additional washing and dewatering, according to individual applications.

“Screening and the solids lifting and dewatering are separate operations, using high-efficiency screening technology to convert the high-flow, low-solids wastewater to low-flow, high-solids dewatering,” Bambridge said.

“Separate screening and lifting equipment makes access simpler for more cost-effective housekeeping and maintenance for lower whole-of-life costs.”

Image caption: CST’s inline rotary fine screening avoids blockages, short-circuiting, maintenance and safety issues.