Marie Holmgard wrote:- >Hi >i work at PCB shop in New Zealand and i am looking at waste treatment >options and water savings for the whole factory. > Hi Marie, We are currently looking at installing an ion exchange recycling plant and the payback period looks like being 3 years on water savings. You still need to treat the regenerant chemicals which have a high metal content. There is also the question of waste chemistry such as tin-lead strippers, copper cleaners, micro-etches, and waste acids which also have to be separately treated. We have a simple settling plant at the moment which keeps our effluent within 4ppm, which is quite generous by todays standards. Acidifying the stream with waste acids, then neutralising with lime to pH 9, then adding flocculating agent and passing through a settling tank give us a good clear effluent stream. This has to be a large plant to cope with the volume and we have to have a regular tanker collection to take away the sludge which is around 99% lime and water. If I had my time again I would go for ion exchange and recycling all rinse waters, with a smaller treatment plant for the concentrated chemistry and regenerants from the ion exchange. You can treat some concentrated copper cleaners which are complexing by passing through selective ion exchange to remove metals only and then neutralise and discharge to drain. This is very cheap. Small ion exchange units can also be fitted to rinses containing metals so they can be discharged without treatment. Your idea of recycling cooling water is good and, as you say, you do need a water cooler in the summer as we found. Your approach will depend on your water costs as recycling is expensive. As Rudy Sedlak has pointed out, you can't put everything in one stream but have to keep certain waste streams from getting into the recycling plant. Also, you can cut down contamination from the worst processes such as the etchants, by using anti-pollution units which rinse boards in clean replenisher solution. By re-using as much water as possible in counterflow rinses, and using water savers to switch off rinses when no panels are going through, a lot of water can be saved and the reduced volume is easier to treat whichever option you choose. To conclude, you will need some form of treamtment of the non-recyclable waste which can be by precipitation and settling. The size of the plant will depend on whether you go for this as an intermediate solution, or implement recycling at the same time in a comprehensive package. Good luck with your plans. -- Paul Gould [log in to unmask] Isle of Wight,UK ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################