Can landfill diversion goals be met when considering the composition of MSW?

Many municipalities, jurisdictions, corporations and states have landfill diversion goals of varying degrees. Many of these near-term goals involve diversion rates ranging from 50 percent up to 90 percent. This diversion counts all material reduction and reuse, including industrial and commercial diversion of materials that never enter the waste stream (for instance, food scraps used for animal feed and cardboard recycling from large box stores).

For many Gershman, Brickner & Bratton (GBB) clients, this material that is not in the waste stream is considered valid diversion, but it can be difficult to quantify. For most in the solid waste industry, landfill diversion means sending materials that show up at the landfill elsewhere to extend the life of a particular landfill.

With an understanding of the composition of the waste coming into a landfill, more realistic diversion can be modeled based on the materials present and their recoverability, assuming current technologies are applied. Similarly, diversion projections can be made by assuming the use of emerging technologies in efforts to reach the higher diversion goals of 90 percent.

Recently, GBB performed a comprehensive waste characterization study to evaluate how a potential mixed waste processing system would extend the life of a county’s landfill. For a conference presentation, GBB generalized this characterization information to identify what could be diverted from the landfill in several different scenarios. This included using traditional mechanical recycling and a large processing system to recover recyclables and organics.

The first scenario assumed all recycling program materials were collected and recovered at the material recovery facility (MRF), and source-separated items such as electronics and yard waste also were collected and recovered. While it is somewhat unrealistic to expect to collect and capture all program materials, this was an exercise in how much diversion would be possible with the current recycling systems in the county. The resulting diversion turned out to be 34.3 percent. This helps illustrate the limits on how much traditional recycling can divert from a landfill.

The next scenario assumed a large residential and commercial mixed MSW processing facility. This processing system would recover organics for an anaerobic digestion facility to produce renewable natural gas and compost. The system also would recover program recyclables and mixed plastics. While these large systems could recover more than 50 percent of the material processed, other unprocessed landfilled materials such as construction and demolition (C&D) materials would keep the overall diversion from the landfill at 42.3 percent.

Counting other external diversions (reduction, reuse, etc.), it seems like achieving 50 percent overall diversion is possible for these jurisdictions with the current technology available; however, these tactics would extend the life of the landfill moderately, which for many locations is ultimately the goal. The current recovery and circularity limitations of much of the waste stream make diversion greater than 50 percent difficult to achieve. Greater diversion would be possible by using remaining material as a fuel for power or cogeneration, but many of the mandated goals explicitly eliminate counting diversion from such technologies.

To increase the recycling of current materials, new technologies are needed to improve circularity. Advanced recycling technologies focused on creating base chemical products for remanufacturing would be able to recover many of the single-use and packaging materials currently found in the waste stream.

Other collection and processing systems for C&D materials, glass and textiles also would contribute to the recovery of even more materials. If nonmechanically recyclable single-use items are recovered with advanced recycling, and large portions of C&D materials, glass and textiles are recovered for recycling using alternative collection and processing, the total diversion from the waste stream could approach or exceed 90 percent.

This lofty goal would require changes in how materials are collected and would rely on the growth of technologies for advanced recycling and textile recovery to a commercial scale, but this helps show how the materials present in the waste stream can be recovered using identified methods to achieve high diversion.