the domestic sewage is pre-treated prior to discharge into the
sewer system (Laugesen et al., 2010). Particularly the contents
of oil and grease and the concentrations of nitrogen were unexpectedly
high. The effluent from the system was meeting the Thai
effluent standards for pH, TSS and TKN, but effluentBODconcentrations
were slightly higher (average 25mgL−1) than the 20mgL−1
effluent standard. Also, the outlet concentrations of oil and grease
were higher than the 5mg L−1 requirement. The concentrations
of faecal coliform bacteria were reduced by nearly 2 orders of
magnitude, however variability in both inlet and outlet concentrations
were high.