Ole manaoga ole okesene vailaʻau, e taʻua foi o le faʻaaogaina o le okesene vailaʻau, poʻo le COD mo le pupuu, faʻaaogaina vailaʻau faʻamaʻi (e pei o le potassium dichromate) e faʻamaʻi ma faʻaleagaina mea faʻamaʻi (e pei o mea faʻalaʻau, nitrite, masima ferrous, sulfides, ma isi) i le vai, ona fa'atatau lea o le fa'aaogaina o le okesene...
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