Jar tests were performed using a six-paddle stirrer. The procedures
consisted of a 2 min rapid mix (200 rpm), 30 min slow mix
(40 rpm), and a 30 min settling period, after which the supernatants
were sampled and filtered by a 0.45 lm pore size membrane
filter. The filtrates were tested for Se concentration. A small
amount of sample was taken immediately to measure Zeta potential
(Zetasizer 2000, Malvern, UK) during the slow mix period.
Before the coagulant dose a predetermined amount of 0.2 mol/L
NaOH or 0.05 mol/L HCl solution was added into water samples
to approximately get an expected pH value. After dosing with coagulants,
water pH was accurately adjusted to the expected value
during the rapid mix period by adding HCl or NaOH solution, after
which the water pH was constant during the subsequent flocculation
process.
Jar tests were performed using a six-paddle stirrer. The proceduresconsisted of a 2 min rapid mix (200 rpm), 30 min slow mix(40 rpm), and a 30 min settling period, after which the supernatantswere sampled and filtered by a 0.45 lm pore size membranefilter. The filtrates were tested for Se concentration. A smallamount of sample was taken immediately to measure Zeta potential(Zetasizer 2000, Malvern, UK) during the slow mix period.Before the coagulant dose a predetermined amount of 0.2 mol/LNaOH or 0.05 mol/L HCl solution was added into water samplesto approximately get an expected pH value. After dosing with coagulants,water pH was accurately adjusted to the expected valueduring the rapid mix period by adding HCl or NaOH solution, afterwhich the water pH was constant during the subsequent flocculationprocess.
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