View Full Version : Anodising legalities

03-01-2014, 10:07 PM
While metal finishing is on my mind, does anybody know the legalities of annodising commercially?

Reason being I'm looking to annodise some small batches, and there's no local annodisers, so I'm looking at fairly high costs/lead times, so I'm looking at the costs of doing it myself.

I've tried googling, but everything I've found so far is for the opposite of the big pond, which seems to be for the vast majority of areas if you're dealing with small quantities, you can just pour the waste produce down the drain provided it's diluted enough!
I some how think our enviromental bods may have a different view on that, but I'm struggling to find an answer.

The only hits I've found for this side of the pond are for companies dealing with hazardous waste, who obviously have an interest in me paying for disposal. So has anybody got any knowledge of this area?

03-01-2014, 11:33 PM
Can you sell it back to the people you bought it off, like they do with waste oil ?

03-01-2014, 11:53 PM
I don't think there's much demand for waste sulphuric acid with various bits of dissolved aluminium...

04-01-2014, 07:21 PM
From Wikipedia

"Anodizing is one of the more environmentally friendly metal finishing processes. With the exception of organic (aka integral color) anodizing, the by-products contain only small amounts of heavy metals, halogens, or volatile organic compounds. Integral color anodizing produces no VOCs, Heavy Metals, or Halogens as all of the byproducts found in the effluent streams of other processes come from their dyes or plating materials.[15]

The most common anodizing effluents, aluminium hydroxide and aluminium sulfate, are recycled for the manufacturing of alum, baking powder, cosmetics, newsprint and fertilizer or used by industrial wastewater treatment systems."

06-01-2014, 09:38 AM
Before disposal you will need to neutralize the waste to PH7 using an alkali which results in non-toxic chemicals, dilution is not usually acceptable as it's impossible for you to add enough water for it to make any difference once your effluent has mixed with all the other waste water feeding into the treatment system.
Water companies usually require initial application & approval followed by testing and logging of quantities with PH readings and occasional lab analysis to ensure that nothing which shouldn't be disposed of is going down the drain, they'll also usually advise if asked,

- Nick

(I've worked in food factories (sweets & jaffa cakes) where neutralization & dumping of acid waste with general waste water is fairly common and wrote the software to run the jam cleanup/neutralization/dumping system for a mini-jaffa cake production line.)

06-01-2014, 01:08 PM
Thanks for that magicniner.

My only issue now is finding out who to speak to!
Where I stay just now, we're essentially off-grid in terms of sewage, using ye olde septic tank and effluent run-off into the local river, so not sure if it'll fall under Scottish Water or SEPA juristiction.
Given how little I'm likely to use, commercial disposal when the need arises may be a cheaper option than any licence fees to the above...

06-01-2014, 02:03 PM
Given that you can buy concentrated (91%) sulphuric acid from B&Q, sold as drain cleaner (http://www.diy.com/nav/fix/plumbing-central-heating/waste-overflows/power_cleaners/One-Shot-Drain-Cleaner-ONESHOT-9271678?noCookies=false), it's surely legal to pour that down the drain, especially when diluted? However I tend to agree that neutralizing it is a kinder idea.

I've used the drain cleaner for anodizing solution and it seems fine. You can also do some fun chemistry experiments with it...

07-01-2014, 07:42 PM
I had a problem disposing of waste sudsoil. My local recycling centre would not take it and the only place that would take it was miles away.
I was eventually advised (by the local council environmental officer !!!) to pour it down the drain (YES). In the end I put it in the bin in a closed container.

In your case, I would imagine that neutralising the solution with sodium carbonate (washing soda) would convert the effluent to chemicals which the sewage system could cope with. I.E. sodium sulphate, aluminium sulphate and carbon dioxide. The Ali sulphate is used in water treatment anyway - remember Camelford ?