Study On Enhanced Coagulation To Treatment Of Humic Acid In Micro-Polluted Water By Modified Bentonite

With the growth of the city population and the development of industry and agriculture, water pollution problems caused by a variety of wastewater discharges have become increasingly prominent, and majority water sources of drinking water were polluted in China. The main pollutants in micro-polluted water are ammonia, organic matters. But conventional water treatment processes typically contains coagulation-sedimentation filtration-sterilization and it can’t remove ammonia and organic matter effectively. Therefore, a sires of safe, efficient, economical and convenient and feasible new decontaminate technologies and materials are needed to be developed.In order to solve the problems exist in conventional water treatment process, this research use C8alkyl glucoside quaternary ammonium compound, C12alkyl glucoside quaternary ammonium compound and AICl3asmodifier. Modified bentonite were prepared by microwave radiation. The removal effect of modified bentonite process homemade humic acid solution was took as a indicator to analysis the prepare conditions of modified bentonite. The modified mechanism of modified bentonite was discussed according to its structural characterization; This experiment examines the factors affecting the modified bentonite to remove HA in micro-polluted water, at the same time, the mechanism that modified bentonite removes HA was explored.Results show that the best modified bentonite in this experiment is C12-Al-bent when the initial concentrate of humic acid is15.0mg/L.The best prepare condition is:M=6.2g/100g, L/S=1.6mL/g, R=20%, Q=120W, t=6min, D=2.0mmol/g.Scanning electron microscope showed that after being modified, the surface characteristics of bentonite changed obviously, the pore structure was improved, and bentonite particles size became small and uniform. Organic salt ions went into the interlayer of montmorillonite mainly includes two kinds of function:ion exchange function and distribution function. But the aluminum-modified bentonite is modified by the interaction function of inorganic metal cations ions exchange, surface reaction, interlayer interaction, hydrolysis reaction, and distribution of the adsorption reaction etc. Modified bentonite has good removal effect on humic acid, and the removal effect of aluminum-bentonite is better than microwave-bentonite due to the coagulation effect of aluminum salt. All reaction conditions include modified bentonite dosage, initial concentration of HA, reaction time, pH value affect the removal of HA. The effect law of Modified bentonite dosage on the removal of humic acid is that the removal rate increased with the dosage increasing, and increasing modified bentonite has little effect on the removal rate of HA after the removal rate peaked. The higher the initial concentration of humic acid was, the worse modified bentonite processed humic acid. The reaction rate of modified bentonite and humic acid is fast, after reacted22minutes, the removal rate of Modified bentonite process humic acid reached more than90%, and it stayed stable when the reaction time increases. Because bentonite has a buffer function, when pH value is among4.0～8.0, so in this range, pH value has little effect on the removal rate of HA, and when it’s strong acid or alkali, modified bentonite poor to process HA. Samples that used modified bentonite combined with PAC had a higher removal rate to HA than those which only used one of them, modified bentonite has enhanced coagulation in this study. Modified bentonite remove humic acid mainly by absortion effect, along with the surface reaction and coagulation effect.