Coagulants, flocculation time and mixing intensity were examined in laboratory studies using a synthetic fulvic acid water and three Swedish water supplies. Alum and polyaluminium chlorides (PACs) of various chemistries were effective when used under favorable pretreatment conditions. Alum and PACs had approximately the same optimum dosages for the fulvic acid water when expressed as mg Al added per mg TOC. An exception was the Ca PAC had a lower optimum dose at higher pH. The PACs were effective at flocculation times as low as 5 min while 10 min was needed with alum, especially in cold waters. Dissolved air flotation (DAF) performance improved slightly with increasing flocculation mixing intensity. DAF performed better than settling for aquatic humic or algae type supplies especially with lower flocculation times, and performed better for a river water with turbidity under cold water conditions. Excellent DAF treatment was achieved with Ca, Si, and sulfate PACs.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Dissolved Air Flotation: Pretreatment and Comparisons to Sedimentation
James K. Edzwald
Donald Q. Bunker
- Springer Berlin Heidelberg