Surface Technology Environmental Resource Center

Toxic Release Inventory (TRI) Pollution Prevention Data

Annually, most metal finishing facilities must submit Toxic Release Inventory (TRI) data by July 1 for the previous calendar year. Among the requirements of TRI reporting, industry must submit information to track progress in reducing waste generation and moving towards better waste management alternatives. In their TRI report some facilities volunteer descriptions of measures they have taken to prevent pollution and reduce the amount of toxic chemicals entering the environment. As a result, TRI serves as a tool for identifying effective environmental practices and highlighting pollution prevention (P2) successes. TRI data are publicly accessible on EPA's TRI Toolbox.

STERC analyzed recent TRI data (2023) to observe what metal finishing facilities are doing in terms of P2. The results of this investigation are summarized in the table below. Column 1 lists the TRI P2 codes most frequently utilized by metal finishers. Column 2 indicates the number of facilities that reported under that code. Column 3 is the sum of waste reduced (from 2022 to 2023) by the reporting facilities. Column 4 presents the methods voluntarily provided by the facilities.

In column 4 there is some overlap of methodology from one P2 code to another. For example, training is mentioned under nearly all of the P2 codes. However, what stands out from this analysis is that waste reduction progress is not complicated. In most cases, it involves:

Communications (e.g., team meetings),
Employee training, and
Process monitoring/control.

And to a lesser extent, it may involve:

Process modifications, or
Equipment purchases

Another key observation is the frequency of which rinsing methods and more specifically drag-out reduction are mentioned. Of the 34 specific P2 methods mentioned by facilities 10 (29%) involve improved rinsing.

In general, P2 methodologies are not capital intensive. They often involve simple changes to procedures, such as rinsing. The TRI reporting facilities also tell us that communications and training are important components to an overall program aimed at reducing waste.

STERC provides a wealth of information relative to P2 and especially rinsing and drag-out reduction. Examples of these resources include:

Pollution Prevention and Control Technologies for Plating Operations (2nd edition). Published by the National Center for Manufacturing Sciences (NCMS), Ann Arbor, MI. this is the most widely referenced book on this subject. The text is now available on-line at no cost. It contains detailed discussion of improved rinsing waste reduction approaches, bath maintenance, processes substitution, chemical recovery, and more.
Rinsing Manual. This manual was produced by the National Center for Manufacturing Sciences (NCMS) through an EPA Grant with assistance from NASF. The purpose of this manual is to help metal finishing facilities improve their rinsing processes. Better rinsing is crucial for high quality production. At the same time, a well-chosen rinse system can save water and minimize sludge generation, leading to reduced pollution and lower operating costs.
Rinsing Systems Calculator. A sophisticated interactive tool that calculates flow requirements and other parameters for multiple rinse tank configurations. The tool takes into account process bath type and concentration, tank temperatures, surface area of parts, drag-out rates, and rinsing criterion.

Drag-out Draining over process tank

Summary of P2 Methodologies Utilized by Metal Finishing Companies

Description of TRI P2 Method (Code)	No. of Facilities Implementing P2 Code	Waste Reduction, lbs.	Facility Specific P2 Methods Implemented
Optimized process conditions to increase efficiency (TRI Code S21)	21	171,146	Better solution control practices led to less bath turnovers, less waste sent offsite, and less zinc used in processes overall. Better management and process control procedures were implemented leading to less bath turnovers and less nitric acid needed for new bath makeups. Our vendors assist in continual efforts to increase efficiency and reduce waste. Extended the process tank life span through increased monitoring which reduced chemical usage (increased life span by 25% which decreased cost and waste). Improved hard chrome amperage calculations for rectifiers to decrease plating duration for reduction of emissions and tank sludge. Implemented quality control testing for electroplating baths and strip solutions and can now rejuvenate tanks for continued reuse as opposed to dumping for offsite treatment and disposal. Were able to eliminate the use of chromic acid flake for solution makeup, resulting in a reduction of chromium purchased and stored onsite. Reduced drag out by increasing rack drip time. Introduction Pt Ti anodes with our PPS plating process.
Other improvements to operating practices and training (TRI Code S44)	17	122,171	Continue to train and monitor processing techniques/methods to identify P2 opportunities. Provided employees with a refresher on drag in and drag methods. Provided dragout reduction training. Fabricated tank covers to lower stack emissions. Quarterly rinse drag-in and drag-out training conducted with production employees to minimize tank dumps. Training events for improved rinsing techniques. Drag-out reduction training and equipment.
Improved scheduling, record keeping, or procedures for operations, cleaning, and maintenance (TRI Code S24)	24	31,944	Implemented production meetings and investigated employee ideas to increase production efficiency and reduce waste. Operating hours on Monday-Friday reduced to decrease utility expenses. Reviewed production schedule on a weekly basis to maintain maximum operating efficiency. Continuously monitor processing techniques that can reduce excess byproducts created during treatment process. Implemented annual dragout training and rinsing techniques to reduce overall bath dumps. Improved rinsing techniques to reduced bath dumps. Conducted dragout reduction training. Reduce the amount of spent chromic acid solution by regular maintenance of hard chrome plating tanks. Held weekly production meetings to optimize production efficiency. All employee suggestions are reviewed for possible improvements to reduce waste. DI unit tanks were repaired which resulted in significantly less hydrochloric acid and sodium hydroxide usages.
Substituted manufacturing aid, processing aid, or other ancillary chemical (TRI Code S04)	4	31,932	Installed a nitric acid recovery unit. Use of alternative masking methods to reduce the use of lead tape. Through vendor assistance changed product to a lesser percentage of nitric acid.
Modified content, grade, or purity of a chemical input (TRI Code S03)	6	6,124	Converted a process from cyanide to a chloride-based plating chemistry. Regularly conduct dragout reduction training. Investigated options for reuse of rinse water. Reduced the amount of sulfuric acid used to brighten aluminum.
Totals	72	363,317