Although no process optimisation was performed, data indicate
that combined anaerobic–aerobic designs are superior to anaerobic
or aerobic only options for treating shampoo wastes. Given that
most PCP factories currently treat their wastes using combined
physico-chemical and aerobic treatment systems, this work provides
a wholly new direction for the treatment of PCP industry
wastes. This is especially true when one considers the very high
cost of aerobic-based treatment systems needed to achieve acceptable
effluent quality; i.e., the 8-day HRT aerobic reactor needed
eight times more energy per COD removed than the HUASB-aerobic
combined system. In fact, similar savings have been seen elsewhere
with other waste types. Gašparicová et al. (2005) achieved
25–40% reduction in energy use in a two-stage anaerobic–aerobic
process compared with aerobic treatment alone with domestic
wastes.