Modelling Mixed Microbial Culture Polyhydroxyalkanoate Accumulation Bioprocess towards Novel Methods for Polymer Production Using Dilute Volatile Fatty Acid Rich Feedstocks

. 2022 Mar 21;9(3):125. doi: 10.3390/bioengineering9030125

ATR-FTIR	attenuated total reflection-FTIR
BOD	biochemical oxygen demand
COD	chemical oxygen demand
DO	dissolved oxygen
FTIR	Fourier transform infrared spectroscopy
HRT	hydraulic retention time
MMC	mixed microbial culture
PHA	polyhydroxyalkanoate
PHB	polyhydroxybutyrate
SBR	sequencing batch reactor
SRT	solids retention time
VFA	volatile fatty acid
VSS	volatile suspended solids
WWTP	wastewater treatment plant
$α$	PHA accumulation inhibition exponent
$C_{o}$	DO concentration (mgO₂/L)
$C_{o}^{*}$	apparent maximum DO (saturation) concentration (mgO₂/L)
$C_{s}$	exogenous dissolved substrate concentration (mgCOD/L)
$C_{s i}$	initial or peak upshift $C_{s}$ (mgCOD/L)
$1 - f_{i}$	$q_{s}^{i}$ / $q_{s}^{m}$
$k_{a}$	aeration oxygen mass transfer coefficient (1/min)
$k_{h}$	Haldane substrate inhibition constant (mgCOD/L)
$k_{i}$	substrate induction constant (mgCOD/L)
$k_{o}$	Monod apparent affinity constant on DO concentration (mgO₂/L)
$k_{s}$	Monod apparent downshift affinity constant on substrate concentration (mgCOD/L)
$k_{u}$	Monod apparent upshift affinity constant on peak substrate concentration (mgCOD/L)
$Q_{o a}$	DO supply rate due to aeration (mgO₂/L/min)
$Q_{o e}$	DO consumption rate due to endogenous respiration (mgO₂/L/min)
$Q_{o p}$	DO consumption rate due to stored PHA (mgO₂/L/min)
$Q_{o s}$	DO consumption reate due to substrate consumption (mgO₂/L/min)
$q_{o p}$	specific $Q_{o} p$ (mgO₂/gVSS/min)
$q_{o s}$	specific $Q_{o} s$ (mgO₂/gVSS/min)
$q_{s}^{r}$	biomass resting specific substrate uptake rate (mgCOD/gVSS/min)
$q_{s}$	specific substrate uptake rate (mgCOD/gVSS/min)
$q_{s}^{e}$	maximum extant specific substrate uptake rate (mgCOD/gVSS/min)
$q_{s}^{i}$	initial maximum extant specific substrate uptake rate (mgCOD/gVSS/min)
$q_{s}^{m}$	maximum specific substrate uptake rate (mgCOD/gVSS/min)
t	time (minutes)
$q_{s}^{r}$	biomass maximum upshift in specific substrate uptake rate (mgCOD/gVSS/min)
$X_{a}$	active biomass concentration (gVSS/L)
$X_{p}$	PHA concentration (gCOD/L)
$Y_{o s}$	yield of oxygen consumed with substrate (mgO₂/mgCOD)
$C_{s f}$	influent feedstock substrate concentration (mgCOD/L)
$C_{s m}$	maintenance volume substrate concentration (mgCOD/L)
$C_{s s}$	stimulation volume substrate concentration (mgCOD/L)
$f_{L}$	applied fraction of maximum possible organic loading rate
$f_{P H A i}$	ith-active biomass element specific PHA level ( $x_{p}$ / $x_{a}$ )
$f_{P H A}^{m}$	active biomass maximum PHA level for $x_{p}$ / $x_{a}$
$H R T_{m}$	HRT in $V_{m}$ due to $Q_{m}$ (min)
$H R T_{s}$	HRT in $V_{s}$ due to $Q_{m}$ (min)
$n_{m}$	number of biomass elements in $V_{m}$
$Q_{f}$	substrate feed (and effluent) flow rate (L/min)
$Q_{m}$	recirculation flow rate (L/min)
$q_{s i}^{m}$	ith-biomass element maximum specific substrate uptake rate (mgCOD/gVSS/min)
$V_{m}$	maintenance volume (L)
$V_{s}$	stimulation volume (L)
$x_{a}$	element specific active biomass (gVSS/element)
$x_{p}$	element specific PHA content (gPHA/element)