Final Report: An Economical Alternative for Sorting Polymers on the Small Materials Recovery Facility (MRF) Level

EPA Contract Number: 68D00278
Title: An Economical Alternative for Sorting Polymers on the Small Materials Recovery Facility (MRF) Level
Investigators: Sommer, Edward J.
Small Business: National Recovery Technologies Inc.
EPA Contact: Richards, April
Phase: II
Project Period: September 1, 2000 through September 1, 2002
Project Amount: $225,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2000) Recipients Lists
Research Category: Hazardous Waste/Remediation , SBIR - Waste , Small Business Innovation Research (SBIR)


1. To assess the long-term effects of particulate and gaseous pollutants on risk of cardiovascular disease (CVD), including fatal and non-fatal coronary heart disease (CHD), during 23 years follow-up (1977-1999) using the unique data from the AHSMOG Study.

2. To assess the long-term effects of ambient air pollutants on risk of fatal and non-fatal CHD among sensitive subgroups (e.g., prevalent CVD, hypertensives, diabetics, elderly).

3. To assess the long-term effects of mixed pollutants on the endpoints in objectives 1 and 2.

4. To investigate the effect of lag-times on the ambient air pollution-CVD association.

5. To explore new methods for exposure assessment and analysis.

Summary/Accomplishments (Outputs/Outcomes):

Based on a market analysis, National Recovery Technologies, Inc. (NRT) found that two different sorting technologies were appropriate. In each case, the removal of polyvinyl chloride (PVC) from the product stream was determined to be critical in increasing the value of the product. Hand sorting, which is the typical method used in MRF facilities, suffers from significant error rates and therefore is unreliable as a means of providing an adequately pure technology. Existing automated technologies are based on either x-ray analysis, such as NRT's VinylCycle®, or near-infrared (NIR) spectroscopic analysis, such as NRT's MultiSort® IR. X-ray systems are not significantly cost-scalable and are not attractive for the MRF environment due to radiation regulations.

NIR spectroscopic analysis is more scalable and is appropriate for MRFs, especially if systems are combined for both contaminant removal and color sorting (which has been found to be the second most needed sort). Combining the enclosure, controls, and electronics for contaminant removal and color sorting into a single sorting unit provides several advantages to the intermediate-sized processor. First, the savings resulting from the combined enclosure, controls, and electronics makes the initial capital investment more attractive. Second, the savings resulting from decreased footprint of the equipment and from there being less conveying necessary results in significant continuing cost advantages to the MRF. Third, integration of the controls and electronics into a single control cabinet serves to centralize process control, allowing the MRF operator to make changes to the way the material is processed without having to move to various locations in the plant.

Combining polymer and color sorting into a single sorting unit presents some unique problems with regards to materials handling. There are two primary methods for sensing and sorting that could be applied. The first method is to sense once and sort twice. This method has the disadvantage that either very precise ejection must be accomplished or the second sorting station is far removed from the sensing station. Furthermore, because two distinct identification technologies are utilized, difficulties arise with integrating the two optics into a single sorting location. The other method is to sense twice and sort twice. This method allows for the two sensing technologies to be entirely separate, with the second sensing technology close to the corresponding ejection station. This method has been shown to yield excellent sorting results at feed rates expected at moderately sized MRFs.

Simply scaling the NIR sorting technology for smaller feed rates does not provide a cost-effective sorting solution for the smallest MRFs, however, because several sorting stations still would be required depending on the actual amount of material to be processed. A significant portion of the cost of an NIR sorting system is associated with the optics and electronics required for each individual sorting station. Reducing the number of sorting stations to one and multiplexing this sorting station to view the entire feed region results in a more cost-effective method for removing the contaminant polymer.

Several multiplexing methods were investigated during this research project. High-speed scanning of the entire material stream width utilizing novel scanning techniques in conjunction with innovative identification and sorting routines was determined to provide sorting ability suitable for small MRF applications.


This research project led to the development of two distinct sorting technologies suitable for small to moderately sized MRFs. A single detection station multiplexed NIR polymer sorting system has been developed for the removal of contaminant polymers for low feed rate sorting applications. This technology is expected to have significant application in the recycling industry, especially at the small MRF level, where the increased value of the recycled polymer will have its greatest impact. A sorting technology that combines NIR polymer sorting with color classification has been developed for larger operations where the increased purity of the product stream as well as the increased value of the clear product as opposed to mixed colors provides significant economic advantages.

NRT's commercialization efforts resulted in sale of two systems based upon the Phase II technology for installation in a recycling facility in the United States. Construction of the units is underway, and installation is scheduled for March 2003.

Supplemental Keywords:

materials recovery facility, MRF, polyvinyl chloride, PVC, recycling, plastics, color sorting, near-infrared spectrometry, NIR, x-ray analysis, polymer, SBIR, small business., RFA, Scientific Discipline, Waste, Sustainable Industry/Business, cleaner production/pollution prevention, Municipal, Sustainable Environment, Technology for Sustainable Environment, New/Innovative technologies, Chemistry and Materials Science, Engineering, Environmental Engineering, municipal waste plastics, waste recycling, waste minimization, waste reduction, recovery, plastics sorting, polymer sorting, municipal waste, recycling, high speed automated sorting, polymers, plastics, materials recovery facility, material recovery facility, pollution prevention

SBIR Phase I:

An Economical Alternative for Sorting Polymers on the Small Materials Recovery Facility (MRF) Level  | Final Report