Uncovering opportunities with waste material assessments

We often hear the phrase “garbage in, garbage out” as it relates to data and analysis. In the waste and recycling industry, when it comes to facilities and operations, this phrase can have both practical and literal connotations. The latest trend is replacing the term “garbage” with “material” to reflect a desire to reduce, reuse and recycle.

To maximize the diversion and recovery of these resources, it makes sense not to refer to our discards as garbage but as materials. But what are we dealing with? What exactly are the materials that we are designing our facilities and operations to manage?

That’s where a waste material assessment comes in.

Waste material assessment basics

A waste material assessment is the systematic study of a material or waste stream to identify the sources, quantities and types of materials generated in a particular area. A material assessment allows an operator to measure the effectiveness of current programs and services, prioritize areas for improvement and, most importantly, create original data that can be used to empower change.

A waste material assessment lays the groundwork for material recovery facility (MRF) design and allows existing MRFs to efficiently address materials management needs. It also can be used to make a justifiable case for funding and resources.

The three main types of waste material assessments are records evaluation, visual assessment and characterization study.

A records evaluation can provide insight into an organization’s material management activities through the examination of a MRF’s operational and financial documentation. Generally, a MRF’s records are essential for demonstrating compliance with regulations and industry standards. This method of assessing a MRF’s material composition can prove cost-effective, as MRF records could readily be available.

A visual assessment is a physical, visual observation (or observations) of materials that can provide a snapshot look at a material stream’s composition but also could include observations of the facility’s conditions and operations. A visual assessment can provide a more rounded and deeper look at a MRF’s processes than a records assessment. However, visual assessments have limitations, including that the data gathered can be based on estimation and, therefore, might not correctly identify and quantify all materials in the waste stream.

A characterization study is the process of collecting random and representative samples of the material or waste stream and manually sorting these samples into individual components by material type. A typical characterization study is more involved than a records evaluation or a visual assessment. It is comprised of three main phases:

• Planning includes organizing the health and safety plan, logistics and staffing and identifying available resources and necessary supplies.
• Fieldwork involves the physical sorting and sampling of materials, typically into approximately 33 different material types for single-stream recyclables.
• Data recording and analysis includes the capture, analysis and management of data to communicate findings.

A material characterization study targets a specific generator or generators (for example, residences, businesses or institutions) or materials (such as organics, pre- or postprocessed materials or residue) to provide reliable, detailed and specific data on the quantity and components of a particular stream.

When combined, MRFs can use vision systems and AI outputs to monitor changes in feedstock characteristics, commodity capture rates and residual composition.

The importance of waste characterization

A MRF’s design ultimately is determined by its local community needs. In general, MRFs typically use a series of mechanical and manual sorting measures to separate a mixed stream of materials from public and private sources. The specific components and technologies of a MRF are based on the volume and composition of materials processed, as well as other factors such as budget goals and/or regulatory requirements.

By studying its feedstock, residuals and commodity characteristics, a MRF will have defensible data to improve its processing capacities and efficiencies to better serve its customers and be more resilient to external challenges, such as fluctuating commodity markets and regulatory changes.

Feedstock assessment

Feedstock assessments are vital to MRF operations, as challenges commonly arise from factors that could be beyond the MRF’s control, such as the uncertainty of material composition (customer compliance), possible variation in material collection programs (source-separated, dual- and single-stream) and hauler methods (compression versus noncompression collection trucks) that impact contamination of the feedstock. Contamination from customers significantly can reduce the value of the processed materials and, therefore, the MRF’s bottom line.

Residual assessment

Residual assessment examines the materials that remain after the recyclable materials have been separated and processed. This is the portion of a MRF’s material stream that generally is considered nonrecyclable or unsuitable for sale and could be sent to landfills for final disposal—typically at a cost to the MRF. Additionally, residual materials such as broken glass can contaminate other material streams given their small size and cause MRF equipment to degrade and malfunction.

Commodity assessment

After a MRF has processed and prepared materials for market, these materials could be sold to a broker, another processor for further treatment or to mills for direct manufacturing use. These materials are commodities with fluctuating values based on factors such as material quality, global events and market demand. MRFs strive to ensure that each bale meets industry and buyer specifications for that material type and grade, which often does include restrictions on contaminants.

A commodity assessment refers to evaluating the price per ton of various materials that a MRF processes and sells. A portion of the income of a MRF is generated by the sale of commodities that are processed at the facility. Each MRF has a unique material composition value that fluctuates with the volume of commodities produced, the amount sold and the price of each commodity type.

Role of artificial intelligence

Artificial intelligence (AI) has the potential to play a significant role in waste material assessments for MRFs and other processing facilities. AI, through vision systems and data outputs from automated equipment, provides the capability to observe and analyze near-real-time material composition and flow rates.

AI’s capabilities have limitations, such as the inability to provide reliable weight information for the individual items it recognizes in the material stream. In addition, if a material is not recognized by AI or is misidentified, it creates an issue as to how to classify that material. With that said, AI can enhance visual assessments and play other roles in MRF operations.

Advances in AI technology introduce the capability to work hand in hand with traditional material assessments. Visual assessments and/or material characterizations can provide valuable calibration data to AI, including individual item weights (or ranges of weights) and boundary parameters for material fractions. Traditional material assessments can provide high precision but are labor-intensive and only provide a snapshot in time. AI can provide an always-on system but must make certain assumptions on material identification and characteristics.

When combined, MRFs can use vision systems and AI outputs to monitor changes in feedstock characteristics, commodity capture rates and residual composition. This then becomes a valuable decision-making tool for owners and operators when they are assessing changes to operations, equipment, maintenance and labor allocations.

The combination of AI and assessments even allows for changes on a more frequent basis. For example, if a MRF services a large event venue that brings material on a sporadic basis, it could change the makeup of the feedstock enough where adjustments to conveyor speeds, tuning of optical sorters and changes to the deployment of manual pickers are justified.

Vision systems and AI do not have to be permanent installations. The camera systems used for AI installations easily can be moved and repurposed for various functions. The same camera system can be repurposed to monitor feedstock, residual content, commodity purity, labor usage, bale counts and safety incidents.

An added benefit is the ability to assist facility operators with recordkeeping. Many metrics can be automated to assist in preparing monthly or annual reports required by regulators or local solid waste planning agencies.

Whether a MRF is looking to improve services, gain industry certification or adapt to new regulations like extended producer responsibility, it is imperative to understand the type and amount of materials that are being generated and managed by local MRFs. A waste materials assessment can uncover opportunities to improve current practices as well as create data for future facilities and investments.

Ricky Phillips is project manager and Steven Schilling is senior project manager at Gershman, Brickner & Bratton Inc., a Vienna, Virginia-based solid waste management consulting firm. They can be reached at rphillips@gbbinc.com and sschilling@gbbinc.com.