Effect of cationic polyacrylamide with cationic microblock structure on dual-flocculant sludge conditioning: performance and mechanism

In this study, sludge conditioned by single and dual flocculants was comprehensively investigated. polyaluminium chloride (PAC) was used as inorganic flocculant, whereas TP (cationic polyacrylamide [CPAM] with cationic microblock structure) and SP (CPAM with random distributed units) were used as organic flocculants. First, the effect of single and dual flocculant dosage on sludge conditioning performance was investigated using turbidity, filter cake moisture content (FCMC), and specific resistance of filtration. The effect of dosing sequence on sludge conditioning performance was also studied. Dual-flocculant conditioning of sludge with PAC and then with TP not only improved sludge dewaterability but also decreased flocculant dosage. Settling behavior was determined for studying the floc characteristics. The effect of charge neutralization on sludge conditioning was investigated by zeta potential. The mechanism of dual-flocculant conditioning mechanism was further summarized with the experimental results.