Optical sorters and robotic sorters may work in two different areas of an MRF. For heavy volumes of a few related commodities (i.e., plastic containers) the optical sorters would be located closer to the front end of the MRF, potentially following an initial separation of light materials versus heavy materials or two-dimensional items such as fiber and paper from three-dimensional items (i.e., containers) by other equipment such as a screen or drum.
In general, a robotic sorter would likely perform better anywhere in the MRF where there is some presorting to spread material evenly across the belt and remove oversize and bulky material, or two-dimensional material like paper and foil, that can obscure the targeted materials. An MRF’s control systems are typically upgraded when optics or robotics are installed to provide the operator more local control of all sorting equipment on the line, more flexibility to address waste stream changes, and simpler control interfaces.
Read up on system information via trade publications; inquire about system performance with other operators; and talk with experienced consultants and vendors. These options will help you narrow down the best option for a facility’s needs. This same information can then be used as a resource when vetting providers.
Allow companies to come into your facility and make an initial assessment, review data you may have on material volume, material changes, and percent recovery and residue. Then request a written report. That report should include: feasibility of employing the machine(s); expected tangible improvements (i.e., rate of recovery, reduction of residue, removal of additional targeted material(s), etc.; any other modifications needed to your system to allow the new equipment to perform properly, a budget cost estimate or range, and estimated operating costs.
Send a representative waste stream sample to potential vendors and have the sample run through the vendor’s test facilities to gauge the equipment’s effectiveness. Operators should visit facilities currently running the equipment under consideration for purchase to see how it operates in person. If visiting a site isn’t possible, review a site’s system layout and analyze its efficiency results.
Bruce Clark, PE, BCES, LEED AP®, is SCS Engineers’ National Expert on Waste Conversion.