2.1. Physical–biological hybrid system
Physical–biological hybrid system can be applied when pollutants
consist of high suspended solids, oil and grease, organic and
inorganic components. Membrane bioreactor (MBR) is one of the
most common physical–biological hybrid systems where it is
increasingly applied in wastewater treatment plants. The advantages
of using MBR technology for wastewater include: (1) capability
of dealing with high volumetric organic loading rates
[13,14]; (2) improved effluent water quality for water reuse since
bacteria and suspended solids which are larger than the membrane
pore size will be retained by membrane [15–17]; and
(3) complete and stable nitrification owing to the retention of
slow-growing nitrifying bacteria at a prolonged solids retention
time