3.4. Experimental methods
Batch oxidation and precipitation tests were
carried out using a jar test apparatus (mod. VELP,
JLT6) equipped with six mixing paddles, timer
and automatic regulator of mixing speed. Based
on the conventional experimental procedure
[25,26], six prismatic beakers with squared crosssection
(12 cm × 12cm × 18 cm) were used, filled
with 1.8 L of sample. Different oxidant doses and
pHs were considered as well as the use of a 35 μm
filter in order to evaluate a prospective full-scale
application of a commercial (ECOMAC SRL,
Italy) self cleaning tangential flow membrane filters
(35 μm mesh).
The procedures of batch oxidation-precipitation
test involved the following steps: a) initial
pH adjustment to the required value of the raw
water in the beakers; b) oxidant addition in the
required dosage; c) rapid mix at mixing speed of
120 rpm for 2 min; d) slow mix at mixing speed
of 30 rpm for 30 min; e) polyelectrolyte addition
during slow mix (when high turbidity levels were
achieved); g) settling for 60 min; h) filtrationthrough a 35 μm filter and/or a 0.45 μm filter
(the filtration was carried out on samples taken from
the beakers at fifteen minutes intervals after the
beginning of the rapid mix).
Before any experimental run, a sample of influent
was collected and analysed. The measured
Mn concentration was then used to evaluate the
potassium permanganate dose for the following
run.