A cross flow microfiltration module fed with a low pressure centrifugal
pump was used to process the pre-filtered wastewater. MF permeate
was directed to a spiral-wound RO membrane by a high pressure centrifugal
pump. A 0.45 μm pore size hydrophilic PVDF membrane (Millipore
Co.) and a thin-film composite polyamide membrane (DOW Filmtec Co.)
were applied for MF and RO, respectively. MF duty was mainly to reject
very small oil droplets and remaining organic materials to reduce RO
fouling. Pretreated water was gathered in the MF feed tank and
was used as feed to MF module. The retentate was circulated to the
feed tank and permeate was gathered in the RO feed tank. The same
procedure was applied for RO and the permeate was collected as water
product of the process. RO was used to separate monovalent and
multivalent dissolved ions, and to produce high quality water product.
Samples were collected in different stages of the process and
chemical analyses were performed based on EPA and APHA standard
methods