polymer plate wash water disposal

I currently manage the type kitchen at the University of Iowa’s Center for the Book. Many of our letterpress students use photopolymer plates, and the water used to wash out their plates has typically been poured down the sink drain. Since much of our city’s greywater goes into the Iowa River (after being treated, of course, though I’m not sure how thoroughly), I’m concerned about trace amounts of polymer ending up in the river.

Does anyone know:

1. what ends up in the water polymer plates are washed in?

2. if these chemicals are removed by the average water treatment facility?

3. a more environmentally-friendly way to dispose of polymer plate wash water than pouring it down the drain?

Thanks,

typekitchenmonitor

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It has been claimed that the dissolved photopolymer is biodegradable, but I don’t have the facts. You definitely need to dilute the waste with more hot water if you send it down the drains, and that is partly to keep the photopolymer from adhering to your drains. It is manufacturer’s recommendation as safe disposal.
One rural printer on septic tank puts the waste waster in a trough, lets it evaporate and harden, and throws the solid waste out with the garbage.

I really like the idea of evaporating the water out from the solution then disposing of the solid. Makes a lot of sense.

I think the essence of the biodegradable aspect is that plastics gradually break down in UV light, but never beyond their polymer base (ie they will always be microscopic strands of plastic), so what gets poured away from a PP wash off is pretty close to what it would break down to.
These pose an environmental risk, as is found in the “plastic soup” in the pacific ocean.

Much depends on the type of plate material you are using. The material in the Jet-manufactured plates is claimed to be both water-soluble and non-hazardous. Here is a link to the product sheet which speaks to this issue:

http://www.jetusa.com/letterpress.html

Of course, if you are dumping any process waste into wastewater heading to the local waste-water processing plant, you may be required to submit data regarding the materials as supplied by the manufacturer. You can contact you plate supplier, they should be able to tell you what the specific nature of the waste suspended in the water would be, and might assure you that it should or should not be dumped into the drain.

typekitchenmonitor

I don’t know that you have to be concerned. Photopolymer plate waste consists of “carbon in organic molecules,” same as your excrement. This does not pose an “environmental risk” when treated. Based on my experience of have to daily clean out my platemaking machine, this stuff doesn’t make it very far as bacteria and associated icky microscopic critters love to eat the stuff.

This isn’t like hard plastic discarded by ships in the Pacific. And the fellow who drys out his photopolymer waste is Patrick Reagh, and he only does so because he has a septic system that he doesn’t want clogged up, because that is what it will do, it adhers. It has even been flushed into drinking water systems to coat over lead in old pipes.

I’ve had various government inspectors of one sort or another look at my set up and they have never issued a concern.

Gerald
http://BielerPress.blogspot.com

Thanks, responders. Very helpful indeed.

tkm