Nanoparticles in wastewater from a science-based industrial park - coagulation using polyaluminum chloride.
The Hsinchu Science-based Industrial Park (HSIP) is the hi-tech manufacturing hub of Taiwan. Wastewater from the HSIP contains numerous nano-sized silicate particles whose size distributions peak at 2 and 90 nm. A 3-5 mg l(-1) as Al dose of polyaluminum chloride (PACl) was used in the field to coagulate these particles, but the removal efficiency was low. Laboratory scale tests indicated that although PACl coagulation removed 52% of the turbidity and 48% of the chemical oxygen demand (COD) from water, its effect on nano-particle removal was minimal. About 58% of the soluble COD was associated with colloidal Si particles. A light scattering test and transmission electron microscopy (TEM) demonstrated that the nano-particles agglomerated in approximately linear aggregates of sizes 100-300 nm. Prolonged contact between residual PACl and the nano-particles generated large aggregates with sizes of up to 10 microm and a fractal dimension of 2.24-2.63. The results presented herein should be of interest in the processing of "high-tech" wastewater that contains nanosized silica particles.
Chang
M R
MR
Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
Lee
D J
DJ
Lai
J Y
JY
D000536:Aluminum Hydroxide / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D013624:Taiwan; D014865:Waste Disposal, Fluid / Q000379:methods*
D007220:Industrial Waste; C016213:aluminum oxychloride; D000536:Aluminum Hydroxide