An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly- aluminum-silicate-chloride （PASiC） in terms of the residual A1 fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual A1 ratio of the composite PASiC coagulant. The main residual A1 sources were the A1 fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00-7.00, while the concentrations of various residual A1 species and the residual A1 ratio of PASiC were minimal at an initial pH range of 7.00-8.00. Under the conditions of OH/AI molar ratio = 2.00 and Si/A1 molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual A1 concentrations. The A1 fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended （filterable） AI fraction was the dominant species, and organic-bound or organo-A1 complex A1 was considered to be the major species of dissolved A1 in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric A1 species dominated the dissolved monomeric A1 fraction.
A coagulation/flocculation process using the composite flocculant polyaluminum chloride-epichlorohydrin dimethylamine （PAC- EPI-DMA） was employed for the treatment of an anionic azo dye （Reactive Brilliant Red K-2BP dye）. The effect of viscosity 01）, basicity （B = [OH]/[Al]） and organic content （Wp） on the flocculation performance as well as the mechanism of PAC-EPI-DMA flocculant were investigated. The η was the key factor affecting the dye removal efficiency of PAC-EPI-DMA. PAC-EPI-DMA with an intermediate η （2400 mPa.sec） gave higher decolorization efficiency by adsorption bridging and charge neutralization due to the co-effect of PAC and EPI-DMA polymers. The Wp of the composite flocculant was a minor important factor for the flocculation. The adsorption bridging of PAC-EPI-DMA with η of 300 or 4300 mPa.sec played an important role with the increase of Wp, whereas the charge neutralization of them was weaker with the increase of Wp. There was interaction between Wp and B on the removal of reactive dye. The composite flocculant with intermediate viscosity and organic content was effective for the treatment of reactive dyeing wastewater, which could achieve high reactive dye removal efficiency with low organic dosage.
