2. Materials and methods
2.1. Reactor set-up
An ABR-septic tank, an YDT-carrier-septic tank and a
conventional septic tank, designated as R1, R2 and R3,
respectively, were installed and operated in parallel. All
three reactors were made from polyvinyl chloride with a
working volume of 24 L (length of 0.52 m; width of 0.23m
and height of 0.3 m). The structure of the three reactors is
shown in Figure 1. R1 was separated into two areas, the
sedimentation area and the baffled flow area, and the volumetric
ratio of the two areas was 1:3. The ratio of the
upflow region to the downflow region was 7:1 in the baffled
flow area. Angles of deflector to the vertical direction
were 45◦. Both R2 and R3 consisted of three compartments.
The YDT carriers had a specific surface area of 300m2 m−3
with a high porosity of 99%. The carriers were added into
the first two compartments of tank R2, and were mounted
in a frame made from wire mesh in the first and second
compartments of tank R2 with a filling ratio of 50%. The
frame was installed in front of the plughole, which is the
hole on the wall between two compartments allowing flow
to pass from the front compartment to the back compartment.
R3 was a scaled down model of a conventional septic
tank available on the market in China.