In Vietnam, a concept was suggested more than 10 years
ago that includes primary sedimentation, anaerobic treatment
in an UASB reactor and aerobic post-treatment
comprising an attached growth reactor and oxidation
ponds (Hien et al. ). However, due to high investment
costs caused by interest rates of more than 20% and slow
enforcement of wastewater regulations, the treatment so far
has been to let the wastewater flow through a series of anaerobic
ponds before being discharged into a river. In the period
2008–2012 a few large factories built anaerobic treatment
units, usually UASB reactors, combined with aerobic ponds
as part of clean development mechanism (CDM) projects.
energy conservation in the production process have been
studied.