>>  how should one dispose of sodium persulphate?

Sodium persulphate is used extensively for sanitizing swimming pools (to
oxidze excessive waste products) (at a rate of a pound or so per 10,000
gallons of pool water.)  It's more of a problem once it's got copper
disolved in it, since it's the copper that's more of an enviormental
poison... (you can still potentially throw it into the swimming pool.
Copper is a popular algicide, in much greater quantitites than you'll
get off a couple of PCBs...)  (do make sure it doesn't contain any of
those mercury-based catalysts I hear are sometimes used.)

That doesn't really answer the question, but we are talking about
relatively benign chemicals...

BillW

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