REMCO ENGINEERING
ENVIRONMENTAL WATER SYSTEMS AND CONTROLS

AQUEOUS CLEANER RINSE RECYCLING SYSTEMS

Cleaning printed circuit boards after wave soldering is difficult enough without the problems associated with environmental compliance. Up to this point, organic cleaners took care of the problem easily. With the switch to aqueous cleaning, the high water use requirements of hot "pure" water rinsing have increased the cost and potential problems of this process significantly. We have looked at the problem for one large (over 20M U.S. per year) assembler and have developed a system for him that reduces is total water use per week to about 3-4,000 gallons for 6 cleaners.

The water is almost completely recycled. An adjustable feed and bleed is allowed at an average of about 1 gpm. Once a week, the system is dumped to prevent the possible build up of some unknown compound and refilled for the next week. Due to its modular nature, the system can be scaled up or down to almost any size. Very small systems would use a modular regeneration system to achieve the same results as very large systems.

One of the problems associated with recirculation of water from a solder flux cleaning operation is that Lead and possibly Copper can build up in the DI resins and when you regenerate the system, the regenerant contains enough heavy metal to make it hazardous. The costs associated with generating hazardous effluent would more than offset any savings in recycling. Our unique approach is to place scavenging columns ahead of the DI system which capture the heavy metal that is generated in the cleaning operation. The small amount generated is easily held from the DI portion of the system so the regenerant is "clean".

Standard Remco Engineering features such as an epoxy coated, bonded fiberglass frame, air operated valves, and sturdy, fiberglass storage tanks are included. The system also features air blowdowns of columns and leaching during regeneration to minimize the amount of water required for regeneration. System capacities from 2 to 200 gallons per minute are available.

The system that Remco Engineering has developed for aqueous cleaner rinse recycling collects the rinse water from one or all of your cleaners and does the following:

1. Exchanges heat from the spent rinse water to the clean DI water.
2. Holds the return water in a buffer tank to balance the system.
3. Filters the water to remove any particulates.
4. Carbon treats the water to remove any organics that may tend to build up in the system.
5. Selectively removes any heavy metal (Lead and Copper) to prevent it from making the regenerant a hazardous material.
6. Deionizes the water to make it pure. Purity is adjustable.
7. Stores the DI water and provides DI water pressure to the facility.

This is an optimized system for a large manufacturer. Individual requirements may vary so some of the listed stages may not be required in all installations.

Requirements (30 gpm system):

Power.................................................................................230/460V 3ph, 10 amps
Water.................................................................................0-1 gpm maximum
Air......................................................................................1 cfm @ 80 psi
Floor space........................................................................10'x 20'x 10'high

Operating parameters (50 ppm return stream):

Water quality (adjustable)
Better than 200k ohms (2ppm)
Storage capacity
3x flow rate(ie,30gpm=900gal)
Heat exchanger capacity
30-40 deg F. differential
Regeneration water requirements
Approximately 3% of total recycled (depends on tds returning from cleaners).
Estimated chemical cost to operate $12/1000 gallons recycled (tds dependent)

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