HBI-94-006-02
Pub. 10/31/94
The amount of pollutants and waste generated by industrial facilities has become an increasingly costly problem for manufacturers and a significant stress on the environment. Companies, therefore, are looking for ways to reduce pollution at the source as a way of avoiding costly treatment and reducing environmental liability and compliance costs.
The United States Agency for International Development (USAID) is sponsoring the Environmental Pollution Prevention Project (EP3) to establish sustainable programs in developing countries, transfer urban and industrial pollution prevention expertise and information, and support efforts to improve environmental quality. These objectives are achieved through technical assistance to industry and urban institutions, development and delivery of training and outreach programs, and operation of an information clearinghouse.
EP3 pollution prevention diagnostic assessments consist of three phases: pre-assessment, assessment, and post-assessment. During pre-assessment, EP3 in-country representatives determine a facility's suitability for a pollution prevention assessment, sign memoranda of agreement with each facility selected, and collect preliminary data. During assessment, a team comprised of U.S. and in-country experts in both pollution prevention and the facility's industrial processes gathers more detailed information on the sources of pollution, and identifies and analyzes opportunities for reducing this pollution. Finally, the team prepares a report for the facility's management detailing its findings and recommendations (including cost savings, implementation costs, and payback times). During post-assessment, the EP3 in-country representative works with the facility to implement the actions recommended in the report.
This assessment evaluated an electroplating facility. The objective of the assessment was to propose a program of pollution prevention that would:
Overall, the assessment identified 18 pollution prevention pollution opportunities at this facility. Recommendations for pollution prevention include replacing the solvent degreaser with an alkaline cleaner, improving process solution monitoring, and capturing and returning 100 percent of chromium dragout to the process solution.
This facility is an electroplater that performs zinc, nickel, brass, and chrome plating. Seventy percent of production is comprised of brass articles. The facility operates with 23 worker who work in a single 8-hour shift, 300 days a year. Approximately 15 m2 of metal surface is finished per day.
Facility operations can be divided into five main steps:
EPA is sponsored by the U.S. Agency for International Development.
The assessment identified 18 pollution prevention opportunities that could address the problems identified above, with significant environmental and economic benefits to the facility. Table 1 [provided in source document] lists the recommended opportunities for the facility, and presents the environmental benefits and implementation costs for each.
As currently performed, the polishing process leaves considerable debris (consisting of a mixture of polishing compound and solids from the polishing wheel) inside the pieces. These deposits cannot be removed by scraping or wiping.
To alleviate this problem, the facility can take several steps. Reducing the amount of polishing compounds used will reduce the amount of debris. Removing visible residue will allow less debris to harden on the pieces. Reducing the time between buffing and cleaning will also allow less debris to harden on the pieces. Lastly, employing a polishing compound that is compatible with alkaline cleansers will improve the efficiency of the cleaning process (along with recommendations outlined in the next section).
The facility currently employs the chlorinated solvent TCE to degrease parts. TCE is highly toxic and chemically reactive, and has been linked to liver cancer and ozone depletion. Parts can be cleaned equally well, or better, through the use of aqueous alkaline cleaners. Thus, the facility can greatly reduce its environmental impact and improve product quality by implementing an alkaline cleaning system. Further, the alkaline system is more cost effective than the TCE system. A $5,000 investment will yield savings (from eliminated solvent purchases) of $12,000 per year.
In this facility's plating process, an acid dip (usually 10 percent sulfuric acid) is used to remove any oxides that may have developed on the brass or steel surface. With time, copper and organic contamination accumulates in the acid bath. If more than 300 mg/l of copper is present in the acid dip, the bath can cause adhesion problems for the steel substrate. Further, copper contamination also impacts the nickel electroplating solution. While the facility utilizes nickel depassivation to remove the copper contamination, it is not efficient, wasting nickel, brightener, and energy.
Separate acid dips for steel and brass substrates will improve the quality of both the steel substrate cleaning, and the nickel electroplating solution, and hence reduce the number of rejects the facility produces. Additionally, by employing tighter process control over the acid dips, the facility will save $816 a year in reduced solution cost.
Cyanide electroplating cannot be eliminated at this facility because the known non-cyanide alkaline alternatives do not function well in this application. However, improved process control and solution monitoring could enhance product quality, and hence reduce the number of rejects the facility produces.
Currently, the facility purifies the nickel bath six times per year. By improving process control and purifying the nickel bath only once per year, the facility should save between $4,100 and $5,900 a year from recovered nickel solution.
The lost chrome solution is only valued at $180 per year. However, if 100 percent of this chrome could be captured, the facility would not have to install expensive chrome waste treatment required by the facility's government. A porous pot purification system (priced between $500 and $1,000) is capable of removing the chromium from the waste water. While the expected costs of meeting chromium discharge limits have not been determined, they are sure to be greater than the cost of the purification system.
Waste water is generated in significant volumes from the facility's rinse steps. Some fairly simple changes can be made that will reduce water use by 25 percent. The use of air or solution agitation would increase the efficiency of the rinses, and reduce the frequency of changes. Spray rinses would also be more efficient than the current practice. Lastly, water inputs should be installed with switches that turn off the inputs after a set period of inactivity. For an investment of less than $100, the facility should save $1,728 a year from reduced water usage.
For further information on this assessment or other activities sponsored by EP3, call the EP3 Clearinghouse at (703) 351-4004, send a fax to (703) 351-6166, or on Internet apendergathabaco.com.