Basically, there are two systems of domestic wastewater and sludge management in Indonesia, on-site and off-site
or sewerage system. In the on-site system, the addition of sludge treatment is needed. The example of on-site system
is personal septic tank, and communal septic tank. Meanwhile, in the off-site system, the sludge treatment is
separated from the source and the pipes are used to drain the sludge to the sludge treatment plants [7]. The plot of
on-site system can be seen in the Fig. 2