2.1. Treatment ponds
A schematic of waste stabilization pond system
(WSPS) of the starch factory is presented in Fig. 1
(Choi, 2001). The wastewater treatment system consists
of 21 APs and facultative ponds (FPs) connected in
series with total area of about 36.5 ha. Out of these, 6
are AP with area of 7.39 ha and 15 are FP with 29.11 ha.
The study concentrated on anaerobic ponds system.
During the study period only four anaerobic ponds were
in operation. The typical size of an AP is approximately
250 m in length, 100 m in width and 4–5 m in depth.
The pond parameters are presented in Table 1. The
anaerobic ponds treat wastewater from a starch as well
as from a glucose factory. The wastewater from the
starch factory was first introduced to Pond #2 and
subsequently flows to Pond #4 while the effluent from
the glucose factory was introduced to Pond #3 and then
flows to Pond #5 where wastewater from the starch and
glucose factory were combined. The combined wastewater
then flows into a series of FPs and treated effluent
was finally discharged on to the groundwater recharge
spreading basins.