Printed Circuit Board Wastewater Recovery
Staying in Compliance, Saving Money, and Improving Overall Product Quality

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Prepared by: Philip Kemp
Vice President, Water Recovery & Reuse Systems
Tenergy Water – New Britain, Connecticut
Additional Overview & Case study pdf (414k)

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More and more shop owners are depending on the services of water treatment experts to address the environmental and economic cost issues associated with printed circuit board manufacturing. Stringent federal and state environmental standards and the growing expense of water reuse have prompted printed circuit board manufacturers to reexamine their facilities’ processes and to take corrective action to reduce waste and cut costs while staying in compliance with changing environmental regulations.

Today, innovative wastewater treatment systems have become the norm in printed circuit board shops across the nation because they are both economical and reliable to operate. The right wastewater treatment solution, custom-designed for each facility, will help manufacturers meet current and future environmental standards and provide significant relief from burdensome costs resulting from printed circuit board manufacturing.

Environmental Compliance

The printed circuit board industry has come under intense pressure in recent years from the Environmental Protection Agency (EPA), as well as its respective state environmental regulatory bodies, to minimize generation of production wastewater. Now more than ever, printed circuit board shops would benefit from an audit and upgrade of their current wastewater treatment processes.

Typical wastes from printed circuit board processes include industrial wastewater and treatment residues; spent process baths; copper sulfate crystals; acids used for cleaning and etching; and ammonia-based etchers. Although shop owners can reduce waste by maintaining a cleaner work environment, performing routine inspections of their printed circuit board processes, and preventing and containing spills, the ultimate safeguard rests with a reliable and effective wastewater treatment system. A printed circuit board manufacturing shop that has an efficient wastewater treatment system is most likely using chemical and wastewater recovery techniques that conserve and reuse process baths, conserve water, reclaim metals and closely manages the level of contaminants that are discharged from the facility.

The Costs

While shop owners face tougher state and federal regulatory standards, they also must contend with the escalating costs associated with printed circuit board manufacturing and the need to compete in a competitive global market. The water treatment costs associated with this process include water purchases and disposal, regulatory compliance, worker safety, operating conditions, and off-site treatment. In many parts of New England, for example, manufacturers deal with the highest water and sewer costs in the country. These costs continue to climb at an alarming rate with industries paying $10 to $15 per 1,000 gallons to purchase and discharge water.

Nationwide, compliance permits are expensive to obtain and maintain. Pending environmental regulations can place the cost for compliance higher than the costs of wastewater recovery systems. Moreover, existing pretreatment systems require an ever-increasing amount of costly chemical addition and handling to meet compliance requirements.

By upgrading or installing a wastewater treatment system best suited for their manufacturing processes, shop owners can realize thousands of dollars in annual savings and improved product quality. Recycling this wastewater saves money because there is less water to purchase, purify, heat or cool, and discharge from the manufacturing facility.

The Challenge

Designing and installing an effective and reliable wastewater solution comes only after careful consideration of the exact processes used in the manufacturing of printed circuit boards. Printed circuit board manufacturers perform numerous process steps such as cleaning, etching, plating, masking and developing. Prior to the design of a wastewater treatment system, water treatment experts examine the general chemistry used in each process step at a given facility to recommend a solution that minimizes the environmental and economical cost concerns of shop owners. The right solution must balance required recycled water quality, wastewater contaminant types, and the capabilities of various decontamination processes.

For example, a successful recycle system installation starts with an effective segregation scheme. Waste streams that have similar chemistries, or demonstrate compatibility, are isolated for treatment. At this point, a thorough review of a printed circuit board manufacturer’s chemical processing steps is required. This includes reviewing Material Safety Data Sheets and chemical manufacturers’ product bulletins, recording rinse station’s flow rates, calculating drag-out volumes, and determining production rates.

Also, good water quality is essential to effective rinsing during printed circuit board manufacturing. Most printed circuit board manufacturing processes use different chemicals in dissolved waters, which may or may not be compatible with chemicals used in subsequent processes.

A close examination by wastewater treatment experts is required to identify the various rinse waters and define their characteristics. It is imperative that the right process be selected for rinse water recovery. Conceptually, the approach for selecting the appropriate removal process for rinse waters is simple: Match the removal process capability and requirements to the rinse water characteristics. However, this can be difficult because the characteristics of the various rinse water are not well defined and the various streams entering the waste treatment facility are not always known.

The “drag-in” of alkaline cleanser residue can have a catastrophic impact on a copper-etching bath’s overall effectiveness. Therefore, it is essential to prevent cross contamination of the various baths used in the manufacturing process and to remove chemical residues. Not only must the rinse water remove contaminants from the board, it must not add new contaminants. The rinses between the different steps are major contributors to water use and are prime candidates for recycling.

One of the major contaminants in printed circuit board manufacturing is surfactants, which are used in the cleaning operations and plating solutions. Water service experts must devise a scheme that will evaluate the presence of surfactants and isolate them for subsequent removal. This manufacturing process also results in the discharge of hazardous rinse water containing nitric sulfuric acid, iron salts, tin, copper and carbonate salts.

The Solution

The goal of printed circuit board wastewater recovery is to design and install a system that ensures a shop owner stays in compliance with state and federal regulations while minimizing the various costs associated with this process.

The wastewater treatment and recovery system calls for physical processes, including cartridge filtration, reverse osmosis, cross-flow filtration, and physical/chemical processes, which involve ion exchange and sometimes straight chemical addition. An effective system uses activated carbon for removal of oxidizers such as hydrogen peroxide, microfilters for lead bearing and pumice-based wastewaters, reverse osmosis for the removal of salts, and an ion exchange system to remove contaminants such as copper, lead and surfactants.

Other keys to a successful wastewater treatment are to identify the sources, volumes, and composition of rinse waters to be treated; to understand the weakness and capabilities of treatment processes; to match the waste streams to be treated to the appropriate process; and to conduct laboratory tests and onsite pilot studies on the proposed waste streams.

The overall recovery capabilities of a regulated system can easily achieve 85 percent to 90 percent recovery of segregated waste streams. If a printed circuit board company wishes to recycle concentrated wastewater, such as developer and photo resist rinses, additional technology can be employed.

Conclusion

Wastewater recycle and reuse technology is a serious concern that should never be taken lightly by shop owners or wastewater treatment experts. Once an effective system is installed and operational, benefits far outweigh the environmental and economical costs for the printed circuit board manufacturer. The cost advantages include water and energy savings, improved rinsing, chemical recovery, reduced loads on Publicly Owned Treatment Works systems, reduced water consumption from municipal water supplies, and an overall better manufactured product. Also, effective water recycling technology can help to minimize the global environmental effect from the industry.

Printed circuit board wastewater can be successfully treated for recycle and reuse, but it is accomplished only by a close partnership between a team of wastewater treatment experts and the manufacturing plant. The end result is a printed circuit board manufacturer that stays in compliance with environmental regulations, saves money, and improves overall product quality.