A Modular Approach to a Polypropylene Recycling Pilot Plant

Hanging Rock, OH

The client engaged Koch Modular for the design and manufacture of a small-scale pilot plant that demonstrates the validity of their patented recycling technology. To provide some background, while polypropylene is one of the most widely used materials in packaging for consumer goods, it is also one of the least recycled. The client’s process addresses this issue by converting waste plastic into ultra-pure recycled polypropylene with properties equal to virgin polymer, tackling global challenges like waste and pollution.

For this process, Koch Modular engineers provided a multi-module pilot plant that incorporates complex mass transfer design, including a series of specialized decantation, extraction, and adsorption processes, to ultimately generate ultra-pure recycled polypropylene. This system simulated commercial production and paved the way to a commercial scale plant.


The complexity of the client’s recycling technology offered unique challenges to Koch Modular engineers. Proper instrumentation selection, piping design that can handle viscous streams, as well as the incorporation of change orders in the project timeline were among these challenges. Given the large amount of equipment necessary for this complex process, Koch Modular engineers were particularly challenged in packaging everything into a working modular system and allowing for proper operator and maintenance access.


The client’s small-scale pilot plant is designed to process various forms of once-used polypropylene to produce polypropylene with effectively virgin or near virgin properties. This is accomplished in a series of process steps involving supercritical absorption, gravity decantation, extraction, and adsorption to remove the contained impurities. Various equipment such as loss-in-weight feeders, extruders, polymer filters, candle filters, adsorbent columns, high pressure pumps, and heat exchangers are used. The final step of the process is a devolatilizing extruder that feeds the purified polymer melt to a pelletizer that generates ultra-pure recycled polypropylene pellets.

Koch Modular also provided an Emerson Process Management DeltaV based DCS control system complete with Main Control Panel, Remote I/O Panels, and Dell PC based Human Machine Interfaces, in addition to the development programming for all control loops, discrete motor/valve control, alarms, interlock function and general operator interfaces.


The system provided by Koch Modular was critical in demonstrating the validity of the client’s technology that converts waste plastic into ultra-pure recycled polypropylene.

A commercial-scale plant now under construction with Koch Modular. The development of this process at commercial scale will provide a much needed response to the global need for recycled polypropylene to reduce landfilling, export of plastic waste, and other environmentally damaging processes.