Fractal characteristics of particle size distribution in dynamic flocculation process

This study selected polyaluminum chloride(PAC) coagulant to remove suspended particles in Kaolin suspension solution and used a turbidimeter and particle counter to monitor the flocculation process online and collected the experiment data. The experiments were conducted to study the dynamic distribution characteristics of suspended particles under different hydrodynamic conditions. The results show the self-similarity and scale invariance of particle size distribution. The study further proposed the concept of fractal dimension of particle size distribution and found out that fractal dimension changed in a similar way as residual turbidity did and could excellently indicate the variation of coagulation effect. Therefore, fractal dimension could be adopted to optimize the addition of coagulants and the quality of outflow could be further improved to reduce production costs.     

The oxidative and adsorptive effectiveness of hydrous manganese dioxide for arsenite removal

This study focuses on the effectiveness of hydrous manganese dioxides (δMnO2) removing arsenite (As(Ⅲ)) from aqueous solution. Effects of such factors as permanganate oxidation, pH, humic acid and Ca2 on As removal and possible mechanisms involved in have been investigated. Permanganate oxidation increases As removal to a certain extent; the higher pH results in the formation of more easily adsorbed As species, contributing to higher As removal; humic acid occupies adsorbing sites and decreases ζ potential of δMnO2, therefore inhibiting As removal; Ca2 facilitates As adsorption on δMnO2, mainly through increasing ζ potential and decreasing repulsive forces between As and surface sites. δMnO2 exhibits oxidative and adsorptive potential for As(Ⅲ), and may be employed as adsorbents or filter coating for As removal in water treatment process.     

Hydrous manganese dioxide adsorbing humic acid： controlling trihalomethane formation

Effectiveness of hydrous manganese dioxide (δMnO2) adsorbing humic acid under different conditions and its subsequent effects on trihalomethane (THMs) formation have been studied. Humicacid removal increases with higher pH and residual TOC decreases from 3.63 mg/L to 1.68 mg/L with pH increasing from 5.5 to 8.5 at 3.0 mg/L δMnO2; δMnO2 exhibits good potential of removing humic acid and the adsorbing potential as high as 1 mg TOC/mg δMnO2 is achieved; the fractional reduction of humic acid with higher molecular weight is about 30% higher than that with lower molecular weight. δMnO2 adsorption obviously reduces subsequent THMs formation; more significant THMs formation reduction is observed for humic acid with higher molecular weight. δMnO2 adsorption is an important factor that contributes to humic acid removal and THMs formation reduction in permanganate pre-oxidation process.     

CFS氧化降解偶氮染料活性黑RB5

研究了复合高铁酸盐溶液(CFS)氧化降解活性黑(RB5)染料废水的反应条件和降解机理.结果表明:CFS氧化降解RB5的最佳pH范围为pH<10,并且在该范围内Fe(VI)的反应速率较快.当pH=8～9,CFS投加量为20 mg·L-1时,氧化反应5 min和20 min时,RB5的脱色率分别为80%和95%.对TOC和COD的去除实验表明,在氧化反应过程中存在有机分子的矿化反应,但矿化速率远低于脱色反应速率.UV-Vis和FTIR结果表明,染料分子中的偶氮基团能被Fe(VI)氧化破坏,并且处理后样品中RB5的特征红外吸收峰消失,说明了染料分子中部分苯环和萘环被破坏,从而使得染料废水的毒性降低、可生化性提高.因此,CFS作为一种高效、低廉的强氧化剂,为染料工业废水的处理提供了一个可行的方法.     

Research of chemical induction unit on mixing effect and chlorine saving

Rapid mixing and chlorine saving are two important problems that most drinking water industries are focus on, and this paper adopts chemical induction unit to compare with water jet injector to study what merits chemical induction unit has. The experiment chose coefficient of variability of chlorine concentration to evaluate the mix effect and used chlorine consumption to compare the two equipments. Distribution reservoir experiments show that chemical induction unit can completely mix chlorine less than 6.2 seconds and water jet injector can not completely mix in 3 minutes. Mixing pool experiments show that chemical induction unit can save chlorine compared with water jet injector, and can save more if more chlorine is consumed.