The effect of oxidants on 2-MIB concentration with the presence of cyanobacteria.
In this study, the effect of three oxidants, sodium hypochlorite, potassium permanganate, and ozone, were tested for the removal of 2-MIB with presence of cyanobacteria. Algae in water samples from the source water of Feng-Shen waterworks (FSW), Taiwan were cultivated at 30 degrees C with continuous light at an intensity between 2,500 and 3,400 lux. During the cultivating process, water samples were analyzed for nutrients, light absorbance at 665 nm (A665), and 2-MIB concentration. The 2-MIB concentrations within the incubated samples increased to as high as 1,000 ng/L to 2,000 ng/L, although no extra nutrients were added to the raw water. After 2 to 3 days incubation, the intracellular 2-MIB concentration was as high as 70% of the total 2-MIB in the samples. The algae that developed were mainly cyanobateria, and more than 90% belonged to the Genus Oscillatorias. An almost 100% removal of both 2-MIB and geosmin in the raw water was observed after ozonation for 10 minutes at a dosing rate of 0.91 mg/l-min. Chlorine and permanganate were much less effective, both removing only about 11% of the 2-MIB within 60 minutes at oxidant concentration of 10 mg/l. Oxidation of the cultivated samples showed that chlorine and permanganate may damage algae cells causing them to release intracellular 2-MIB. During the 60 minutes of reaction time, the total 2-MIB concentrations (intracellular plus dissolved) varied by no more than 10%, however, the ratios between dissolved and total 2-MIB concentrations increased. Two effects of ozonation on the 2-MIB concentration in the cultivated samples were observed when the algae were young, namely 2-MIB release from damaged cells and 2-MIB oxidization. The rates of 2-MIB release and 2-MIB destruction were similar. However, old algae cells were more easily damaged. As a result, intracellular 2-MIB was released faster, and the soluble 2-MIB was destroyed more quickly by ozonation.
Tung
S C
SC
Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan. p5889108@dec4000.cc.ncku.edu.tw
Lin
T F
TF
Liu
C L
CL
Lai
S D
SD
D001892:Camphanes / Q000737:chemistry* / Q000302:isolation & purification*; D000458:Cyanobacteria / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry*; D010083:Oxidants, Photochemical / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*; D011196:Potassium Permanganate / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D001892:Camphanes; D016877:Oxidants; D010083:Oxidants, Photochemical; D011196:Potassium Permanganate; C005536:2-methylisoborneol; D010126:Ozone; D012973:Sodium Hypochlorite