# Disposal of rinsing water



## siddharta (Dec 21, 2012)

Hello,

I am prepairing papers for an environmental approval. I have to state what I will be doign with waste water from processes. 
I am stating that I will be using only AP process and waste water will be rinsing water frop AP. What would be best way of disposing it legally? 
I don't remember to read about metal and salt contamination of rinsing water. In my mind there would be some Ph issues, but nothing you can't deal with. But I doubt that only neutralization will solve this issue. Any thoughts on this matter?

B.


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## Geo (Dec 21, 2012)

remove metals and bring the PH to neutral. if you use iron to cement with, all you will have left is rusty salt water. test PH with test strips or PH meter and bring PH to near 7.


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## siddharta (Dec 21, 2012)

I was thinking in the same direction. But what if Ph is not acidic enough to cement with iron? Add acid, cement and neutralize?


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## Geo (Dec 21, 2012)

any solution that holds metal salts has to be acidic. if it was not acidic, the salts would drop out on their own. i dont believe you would have to add any more acid to cement with iron.


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## siddharta (Dec 21, 2012)

Ok I will write this down and keep you posted what will answer be.  Thanx


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## ericrm (Dec 21, 2012)

Geo said:


> remove metals and bring the PH to neutral. if you use iron to cement with,* all you will have left is rusty salt water.* test PH with test strips or PH meter and bring PH to near 7.


that is not thru geo...
what you have is dissoved iron chloride in water.... and if you use .sodium hydroxide to raise your ph, your making some kind of hydroxide (now i dont know about the lagality to dump iron hydroxide...)

also i aint even sure that it is legal to dump massive ammount of salt water without proper autorisation...


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## Geo (Dec 21, 2012)

dont use hydroxide. use limestone.its cheap and plentiful.limedust is used to spread on gardens to raise the PH in the soil to make it less acidic. salt is used as a melting agent for ice in the winter. i cant imagine a country that doesnt use it for that purpose. its cheap and plentiful.salt is in everything even in the foods we eat to the urine we expel.every waste we produce contains salt. what makes a liquid toxic is chemical content and heavy metals. after you remove all the metals higher in the reactivity series than iron, all you have to worry about are the chemicals.raising the PH only makes it less acidic but if you are only using the chemicals we normally use and not something exotic you should be ok just neutralizing the solution.


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## ericrm (Dec 21, 2012)

geo the probleme is the same
he is trying to get a paper for a legal autorisation , using limestone will make iron carbonate rather than an hydroxide but still, as soon as you talk legality theyr is always more issue than just working just for you... if i may say it like that...


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## Geo (Dec 21, 2012)

i certainly hope rust never becomes illegal here. i cant say what may or may not be considered acceptable in other countries but it seems to me that naturally occurring compounds should pose no problems. i hope everything turns out ok for him. i can think of a couple other processes that consolidates and collects all the contaminants in a sludge like substance but that leaves you with truly toxic waste to dispose of.


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## NoIdea (Dec 22, 2012)

Hmmm, disposal? Why not try a more creative approach, where by, recover, and reuse rather than disposal.

I personally evaporate my solutions. 

One possible method would be to use the aluminium from electrolytic capacitor and sodium hydroxide to generate hydrogen gas, which in turn, with a little heat can reduce metal salts to their metals and regenerate the acid. The metal produced this way appears (visually) cleaner.

Yes you could still use the aluminium to drop the copper from solution butt the above is more fun. :lol:

Deano


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## lazersteve (Dec 22, 2012)

Somehow my reply to this thread seems to have ended up in another thread with several other posts here:

More on disposal of waste solutions

Using iron and pH shift to 7 alone is not sufficient to guarantee removal of all hazardous metals in the solution. A lot of the effectiveness of this (iron then pH 7) quick disposal technique, depends on the source scrap, the method use to recover, and the source of iron used to cement the dissolved metals.

Here's the MSDS for red iron oxide (Rust):

Red Iron Oxide

and the definition of rust:

Define Rust

Steve


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