138
Table 5.4 Summary of various process design approaches to promote polyhydroxyalkanoates accumulation
Process
Phase Aeration Electron/acceptor
Energy supply
Carbon supply
Nutrient
availability
Cause for
polyhydroxyalkanoates
accumulation
Anaerobic-aerobic Feast
Famine
No
Yes
Polyhydroxyalkanoate
O
2 /NO
3
−
Glycogen/
polyphosphate
Polyhydroxyalkanoates
oxidation
External substrate
Polyhydroxyalkanoates
Yes
Yes
Lack of electron/acceptor
Transient substrate
Aerobic dynamic
feeding (ADF)
Feast
Famine
Yes
Yes
O
2
O
2
Substrate oxidation
Polyhydroxyalkanoates
oxidation
External substrate
Polyhydroxyalkanoates
Yes
Yes/no
Transient substrate
ADF with
intermediate
settling
Feast
Famine
Yes
Yes
O
2
O
2
Substrate oxidation
Polyhydroxyalkanoates
oxidation
External substrate
Polyhydroxyalkanoates
Yes
Yes
Transient substrate
Settling pressure
Elimination of COD from
famine phase
ADF with
feast-phase N
limitation
Feast
Famine
Yes
Yes
O
2
O
2
Substrate oxidation
Polyhydroxyalkanoates
oxidation
External substrate
Polyhydroxyalkanoates
No
Yes
Transient substrate
N limitation during feast
phase
Photosynthetic
sequencing batch
reactor
Feast
Famine
No
No
Polyhydroxyalkanoate
Algal O
2
Light
Polyhydroxyalkanoates
oxidation + light
External substrate
Polyhydroxyalkanoates
Yes
Yes
Lack of external electron/
acceptor in light
Transient substrate
Photosynthetic
dark feast phase
Feast
Famine
No
No
Polyhydroxyalkanoate
Algal O
2
Glycogen
Polyhydroxyalkanoates
oxidation + light
External substrate
Polyhydroxyalkanoates
Yes
Yes
Lack of external electron/
acceptor in light
Transient substrate
Photosynthetic
permanent feast
Feast
only
No
Polyhydroxyalkanoate Light
External substrate
Yes
Lack of external electron/
acceptor in light
Aerobic-anoxic
Feast
Famine
Yes
No
O
2
NO
3 /NO
2
Substrate oxidation
Polyhydroxyalkanoates
oxidation
External substrate
Polyhydroxyalkanoates
Yes
Yes
Transient substrate
S. Sali and H. R. Mackey