Page 433 - Industrial Wastewater Treatment, Recycling and Reuse

Application of Anaerobic Membrane Bioreactor 405

include the moving bed biofilm reactor (MBBR), the fluidized aerobic
bioreactor (FAB), the sequencing batch reactor (SBR), and the membrane
bioreactor (MBR). In principle, the MBBR uses a combination of sus-
pended and attached growth processes of biological wastewater treatment.
Such systems utilize specially designed carrier material for the growth of bio-
film, which is held in suspension within the bioreactor. The MBBR system
is a great improvement over conventional extended aeration or ASP and
provides a robust and compact facility in a fully enclosed design. No sludge
recirculation is required to maintain an active biomass in the bioreactor as in
the case of conventional ASP. The MBBR system takes higher shock loads
without reducing the plant performance because of the large quantity of
active biomass available inside the reactor.
The SBR is a fill-and-draw activated sludge system for wastewater treat-
ment. In this system, wastewater is added to a single “batch” reactor, treated
to remove undesirable components, and then discharged. Equalization, aer-
ation, and clarification can all be achieved using a single batch reactor. To
optimize the performance of the system, two or more batch reactors are used
in a predetermined sequence of operations. The unit processes of the SBR
and conventional activated sludge systems are the same. The difference
between the two technologies is that the SBR performs equalization, bio-
logical treatment, and secondary clarification in a single tank using a timed
control sequence.
MBBR and SBR technologies are gaining acceptance due to a small foot-
print area and recyclable quality of effluent. MBR technology, which com-
bines the biological-ASP and membrane filtration, has also become more
popular recently. In MBR technology, the suspended solids and microorgan-
isms are separated from the treated water by membrane filtration. Compared
with conventional wastewater treatment processes, MBRs offer several
advantages including high biodegradation efficiency, excellent effluent qual-
ity, smaller sludge production, and compactness. As a result, MBR can offer
an attractive option for the treatment and reuse of municipal wastewater.
Because of further technical developments and significant cost reductions
to some extent, the interest in MBR technology for municipal wastewater
treatment has sharply increased; however, deployment of MBR technology
inIndiaisfacingsomechallengesbecauseofhugecapitalrequirementsandthe
operating cost of the technology. Other factors, such as membrane fouling,
necessity of critical pretreatment, and membrane replacement cost are also
impacting on the implementation of MBR technology in India.