3.3. Effects of MLVSS, OLR and SLR on SBR performance
3.3.1. Effect of MLVSS concentration on BOD, COD and TSS removal
An adequate MLVSS concentration is maintained to ensure
biomass concentration (bacterial population) is sufficient for biological
reaction to take place during the aerobic degradation, so that
process does not become overloaded (Ng, 2006; Vijayaraghavan
et al., 2007). A minimum MLVSS concentration is also critical to
allow the development of a flocculent biomass. If the process is
operated at MLVSS concentrations which is below the minimum
value, bioflocculationwill be poor, entrapment of particulate organic
matter will be inadequate, and a good settling activated sludge floc
will not be obtained (Leslie Grady et al., 1999). Metcalf and Eddy (2003) stated a desired biomass concentration of 3000e6000 mg/
L MLSS for effective functioning of an activated sludge reactor.
However, when treating high organic strength wastewaters such as
the anaerobically digested POME with influent COD of
10,000e15,000 mg/L, the MLSS level stated above is insufficient to
treat the wastewater efficiently. It seems plausible that the failure of
the SBR in the study conducted by Fun et al. (2007) which aimed to
bring the treated effluent to within the effluent standard is attributed
to the insufficient MLSS concentration (2500e4000 mg/L)
(Table 1). Hence, MLSS concentration (i.e. MLVSS) is an important
factor in controlling the efficiency of aerobic treatment system and
becoming a greater concern as treatment systems are pushed to
work at their limits to meet more stringent regulations.
3.3. Effects of MLVSS, OLR and SLR on SBR performance3.3.1. Effect of MLVSS concentration on BOD, COD and TSS removalAn adequate MLVSS concentration is maintained to ensurebiomass concentration (bacterial population) is sufficient for biologicalreaction to take place during the aerobic degradation, so thatprocess does not become overloaded (Ng, 2006; Vijayaraghavanet al., 2007). A minimum MLVSS concentration is also critical toallow the development of a flocculent biomass. If the process isoperated at MLVSS concentrations which is below the minimumvalue, bioflocculationwill be poor, entrapment of particulate organicmatter will be inadequate, and a good settling activated sludge flocwill not be obtained (Leslie Grady et al., 1999). Metcalf and Eddy (2003) stated a desired biomass concentration of 3000e6000 mg/L MLSS for effective functioning of an activated sludge reactor.However, when treating high organic strength wastewaters such asthe anaerobically digested POME with influent COD of10,000e15,000 mg/L, the MLSS level stated above is insufficient totreat the wastewater efficiently. It seems plausible that the failure ofthe SBR in the study conducted by Fun et al. (2007) which aimed tobring the treated effluent to within the effluent standard is attributedto the insufficient MLSS concentration (2500e4000 mg/L)(Table 1). Hence, MLSS concentration (i.e. MLVSS) is an importantfactor in controlling the efficiency of aerobic treatment system andbecoming a greater concern as treatment systems are pushed towork at their limits to meet more stringent regulations.
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