216
A. Z. Yaser and N. N. Safie
Table 3
(continued)
TOT
Sewage treatment
Advantages
Disadvantages
References
Attached growth
Trickling filters
Rotating biological contactors (RBC)
Fixed media submerged biofilters
Granular media biofilters
Fluidized bed reactors
Conventional biofilm reactors (FBR
and MBBR)
High biomass concentrations are
reached in trickling filters and RBC (>
20 kg TSS/m 3
) resulting in a high
treatment capacity
Provided with some variants a higher
biomass concentration is feasible,
leading to an efficient treatment with a
more compact system
Greater resistance to toxicity due to
physiological differences and also by
the protective effect of the
extracellular matrix to the attached
biofilm
The trickling filter is not
volume-effective.
Conventional RBC was reported to
have long start-up time and low
capacity and low COD removal. It is
difficult to get even distribution of the
load on the whole carrier surface in
fixed media submerged biofilters.
The granular media biofilters have to
be operated discontinuously because
of the need for backwashing and many
of the fluidized bed reactors show
hydraulic instability.
Conventional biofilm reactors are
prone to clogging at high organic
loading rate and particulate matter
which resulting in frequent backwash
Odegaard et al. (1994), Gupta and
Gupta (1999), von Sperling (2007),
Cervantes et al. (2006)
TOT—Type of treatment