CASE STUDY

CST Wastewater Solutions | Wastewater Screening & Conveying Systems

CST Wastewater Solutions designs and supplies specialist screening and solids handling equipment for municipal and industrial wastewater treatment facilities. Demand increased for robust pre-treatment systems that protect downstream processes and support regulatory compliance, so CST engaged Caliber Design to provide mechanical engineering support across multiple projects.

Over a 15-month period, a Caliber engineer was seconded remotely to work as part of CST’s engineering team. Caliber’s role focused on detailed mechanical design, 3D modelling, and fabrication-ready documentation for rotary drum screening systems and associated screw conveyors.

KEY TASKS

• Refined equipment geometry to improve solids separation, minimise head loss, and simplify maintenance.

• Documented operational parameters, capacities, and component specifications to guide fabrication and installation.

• Validated and refined designs in collaboration with CST engineers to ensure compliance with relevant industry standards and fabrication requirements.

HOW WE DELIVERED

Caliber supported CST Wastewater Solutions across multiple wastewater treatment projects, providing mechanical design expertise from concept refinement through to fabrication-ready documentation. Working remotely as part of CST’s engineering team, our engineer embedded into CST’s workflows and design standards, enabling efficient iteration and consistent delivery across multiple systems.

The work centred on the detailed design of CST’s rotary drum screening systems. These horizontally installed, self-cleaning screens use a stainless steel rotating drum with mesh or wedge-wire panels to capture fine solids while allowing screened water to pass through. Flow plates direct water radially through the drum to improve separation efficiency and support self-cleaning. Captured solids are collected in an integrated hopper and discharged via a shaftless lifting and dewatering screw, with screening and solids handling separated to simplify maintenance.

Using Autodesk Inventor, 2D general arrangement drawings were developed into detailed 3D models of rotary drum screens, tanks, screw conveyors, and supporting structures. These were converted into fabrication and assembly drawings specifying materials, tolerances, finishes, and interfaces for stainless steel manufacture. Designs targeted high screening efficiency for solids in the 2 to 5 mm range while maintaining low head loss for high flow applications.

Screw conveying systems were designed to complement the rotary drums, with shaftless or conventional configurations selected based on solids characteristics. Adjustable pitch and diameter were used to optimise throughput and dewatering, with enclosed stainless steel construction supporting plant hygiene and odour control.

Site-specific layouts integrated new equipment into existing treatment plants, accounting for architectural constraints, existing infrastructure, and maintenance access. The horizontal equipment layout kept critical drive components above water, supporting safe access and simplified long-term maintenance.