At the end of continuous operation of the UASB reactor,
batch recirculation experiments were carried out two
times to determine the maximum removal of COD fractions
in grey water. In each batch recirculation experiment,
the storage tank was filled with 28 L of grey water (4 times
of the UASB reactor volume). Then, the UASB reactor was
fed with the wastewater for a period of three HRT
without wastewater recirculation. The aim of this step
is to guarantee that the wastewater in the reactor will be
similar to the recirculated wastewater. After that, the
remaining grey water in the storage tank was recirculated in
the UASB reactor for a period of five days. The COD fractions
of the recirculated wastewater in the storage tank were
measured in time