纳米SiO2与聚合铝PAC对含有机微污染物低浊水的絮凝形态学特性

FLOCCULATION MORPHOLOGIC PROPERTIES OF SILICA NANO-PARTICLES AND POLYMERIC ALUMINIUM CHLORIDE (PAC) TO LOW TURBIDITY RAW WATER CONTAINING ORGANIC MICRO-POLLUTANTS

在含有水溶性有机微污染物-十二烷基硫酸钠(SDS)的6NTU高岭土悬浊液中,投加纳米SiO2稳定分散液与聚合铝PAC进行动态混凝试验与静沉试验,借助图像分析技术与分形理论,探讨了纳米SiO2与PAC对含水溶性污染物低浊水的絮凝形态学特性。结果表明:絮体结构及其形成过程具有分形特征。参数"分维D"可用于定量表征分形絮凝体的形态学特性与分形结构的动态演变规律;絮凝体生长模式从开放的分枝状DLCA结构逐步向密实的RLCA构型演变。分形结构的不断演变引起絮体内部渗透性变化,絮体沉降性能逐步改善,分维值升高;SDS的存在对絮凝初PAC的混凝起阻碍作用,纳米SiO2能使颗粒生长的速度加快。纳米SiO2有助于有机物的去除,但对无机杂质的去除效果不如PAC;以纳米SiO2为助凝剂,能促使PAC絮体有效质量密度增加,使PAC对SDS的去除率提高,分维值增加。

For 6NTU Kaolin suspensions containing an aqueous organic micro-pollutant - sodium dodeeyl sulfate （SDS）, dynamic coagulation experiments and quiescent sealing tests were done by adding silica nanopartieles stable dispersion solution and Polymeric Aluminium Chloride （PAC）. Using image analysis technology and fractal mathematic theory, floceulation morphologie properties of silica nanopartieles and Polymeric Aluminium Chloride （PAC） to low turbidity water was discussed. Results showed as follows： Structures and formation processes of floes have fraetal properties, which can be quantitatively characterized by ＂fractal dimension＂ D; The growth mode of floes can change from open-braehing DLCA structure to compact RLCA configuration little by little. The continuous evolution of fractal structures causes various permeability interior floes. The sealing behaviors of floes can be improved step by step and fractal dimension value increases; SDS can interfere in floes formation at the initial floceulation stage. Aider the addition of silica nanopartieles, the growth rates of particles can be quickened; Silica nanopartieles are beneficial for removal of organic matters, but the removal effi- ciency of silica nanopartieles to the inorganic matters is not as good as PAC; When PAC serves as a primary coagulant, the floeeulant aid- silica nanopartides can enhance efficient mass density of PAC floes, hence,removal rate of PAC to SDS improves markedly and fraetal dimension value increases.