Evaluating the performance of conventional DAF and PosiDAF processes for cyanobacteria separation at a pilot plant scale

Abstract In this work, a commercially available water treatment polymer poly(N,N-diallyl-N,N-dimethylammonium chloride) (PDADMAC) and hydrophobically modified (HMP) designed to adhere bubble surfaces were applied for the first time in novel Posi-dissolved air flotation process (PosiDAF) that uses polymer-modified bubbles, at pilot-scale of waste stabilisation pond samples rich algae. It was found PDADMAC PosiDAF gave comparable removal achieved using conventional DAF >95% cell separation. Furthermore, float layer more uniform thicker with up 8% solid contents compared DAF, which comprised discrete floc clusters an average concentration ∼4.1%. contrast use PDADMAC, application HMP did not achieve similarly good separation pilot scale. hypothesised may be due micellisation on surface, creating unstable bubbles coalesced prevented polymer–bubble–cell interactions, are crucial effective On comparison costs it resulted cost-savings 74% low chemical consumption. summary, reduced cost increased metal-free float.