Page 440 - Industrial Wastewater Treatment, Recycling and Reuse

Application of Anaerobic Membrane Bioreactor 411

total nitrogen, and total phosphorus were achieved at 93%, 67.4%, and
94.1%, respectively. Van Zyl et al. (2008) studied the treatment of simulated
petrochemical industry wastewater using a submerged AnMBR, and in that
study, the AnMBR achieved a very high COD removal efficiency at OLRs
3
up to 25 kg COD/m /day during long-term operation.
Bailey et al. (1994) studied upflow anaerobic sludge bed reactor perfor-
mance using cross-flow microfiltration and reported COD removal as high
as 99%, with high effluent quality. Many anaerobic MBR systems have been
3
operated at OLRs ranging from less than 5 to over 30 kg COD/m /day.
AnMBRs are expected to provide more efficient digestion with a smaller
size than conventional anaerobic digesters. These advantages, together with
increased stringency in waste disposal for animal production facilities, have
led to pilot scale testing of AnMBRs to treat swine waste (Du Preez et al.,
2005; Lee et al., 2001).
The main challenge for AnMBRs has been the fouling of membrane
units. High fluid flow velocities resulting in high shear rates at the surface
of the membrane can be used in AnMBRs with external membrane units
to reduce membrane fouling caused by the adhesion of biomass and colloidal
organic matter to the membrane surface (Stephenson et al., 2000). However,
the digestion efficiency in AnMBRs may be negatively affected by exposure
of the biomass to high shear conditions.
An opportunity in applying AnMBR for low-strength wastewater treat-
ment is identified, and literature indicates that few researchers have
attempted studies on AnMBR for low-strength wastewater treatment.
Energy recovery and reuse of treated effluents are major considerations of
interest in using AnMBR for low-strength wastewater treatment. Even
though the energy recovery from low-strength wastewater is fairly low
due to low organic content, the reuse option of treated effluent is another
eye-opening interest. Current trends in research publications indicate a large
number of AnMBR studies in industrial high-strength wastewater treat-
ment. At the same time, the number of studies on municipal wastewater
treatment has also increased considerably. Figure 10.6 shows the number
of articles published in journals on AnMBR research related to municipal
and industrial wastewaters. Given that anaerobic processes have few limita-
tions for complete nutrient removal, the treated effluent consists of higher
concentrations of nitrogen and phosphorus. In such cases the treated effluent
can be reused for irrigation purposes in agriculture.
Many reviews indicate that the AnMBR has advantages over conven-
tional aerobic-based technologies, and the integration of membrane