# -*- coding: utf-8 -*-
# BioSTEAM: The Biorefinery Simulation and Techno-Economic Analysis Modules
# Copyright (C) 2020-2024, Yoel Cortes-Pena <yoelcortes@gmail.com>
# 2023-2024, Yalin Li <mailto.yalin.li@gmail.com>
#
# This module is under the UIUC open-source license. See
# github.com/BioSTEAMDevelopmentGroup/biosteam/blob/master/LICENSE.txt
# for license details.
"""
This module contains unit operations for wastewater treatment of a
cellulosic ethanol biorefinery as in [1]_.
.. contents:: :local:
Data
----
.. autodata:: biosteam.wastewater.conventional.non_digestables
Unit operations
---------------
.. autoclass:: biosteam.wastewater.conventional.AnaerobicDigestion
.. autoclass:: biosteam.wastewater.conventional.AerobicDigestion
.. autoclass:: biosteam.wastewater.conventional.ReverseOsmosis
.. autoclass:: biosteam.wastewater.conventional.WastewaterSystemCost
Utilities
---------
.. autofunction:: biosteam.wastewater.conventional.get_digestable_organic_chemicals
System factories
----------------
.. autofunction:: biosteam.wastewater.conventional.create_conventional_wastewater_treatment_system
References
----------
.. [1] Humbird, D., Davis, R., Tao, L., Kinchin, C., Hsu, D., Aden, A.,
Dudgeon, D. (2011). Process Design and Economics for Biochemical
Conversion of Lignocellulosic Biomass to Ethanol: Dilute-Acid
Pretreatment and Enzymatic Hydrolysis of Corn Stover
(No. NREL/TP-5100-47764, 1013269). https://doi.org/10.2172/1013269
"""
from biosteam.utils import remove_undefined_chemicals, default_chemical_dict
import biosteam as bst
import thermosteam as tmo
from thermosteam import (
utils,
settings,
separations,
Reaction as Rxn,
ParallelReaction as PRxn,
)
cost = bst.decorators.cost
__all__ = (
'AnaerobicDigestion',
'AerobicDigestion',
'ReverseOsmosis',
'WastewaterSystemCost',
'SludgeCentrifuge',
'get_digestable_organic_chemicals',
'create_conventional_wastewater_treatment_system',
)
# %% Functional utilities
#: list[str] IDs for non-digestible components in wastewater
non_digestables = ['WWTsludge', 'Cellulose', 'Xylan', 'CellulaseNutrients',
'Mannan', 'Lignin', 'Galactan', 'Glucan', 'Acetate',
'Biomass', 'Arabinan', 'Tar', 'CO', 'CO2', 'CH4']
[docs]
def get_digestable_organic_chemicals(chemicals):
"""
Return a list of digestible organic chemical IDs.
Parameters
----------
chemicals : :class:`~thermosteam.Chemicals`
Digestible organic chemicals will be retrieve from this parameter.
"""
non_digestable_chemicals = set([chemicals[i] for i in non_digestables if i in chemicals])
digestables = [i for i in chemicals if i not in non_digestable_chemicals]
return [i for i in digestables if i.locked_state != 'g' and 'C' in i.atoms]
def anaerobic_digestion_reactions(
chemicals, MW_sludge,
biogas_CH4_fraction=0.51, # mol-CH4 / mol-biogas
organics_to_biogas=0.86, # g-biogas / g-reactant
organics_to_biomass=0.05, # g-biomass / g-reactant
thermo=None,
):
# Defaults are based on P49 in Humbird et al., 91% of organic components is destroyed,
# of which 86% is converted to biogas and 5% is converted to sludge,
# and the biogas is assumed to be 51% CH4 and 49% CO2 on a dry molar basis
MW_CH4 = 16.04246
MW_CO2 = 44.0095
x_CH4 = biogas_CH4_fraction
x_CO2 = (1. - x_CH4)
MW_biogas = x_CH4 * MW_CH4 + x_CO2 * MW_CO2 # g-biogas / mol-biogas
conversion = organics_to_biogas + organics_to_biomass # g-reacted / g-reactant
f_biogas = organics_to_biogas / (conversion * MW_biogas) # mol-biogas / g-reacted
f_sludge = organics_to_biomass / (conversion * MW_sludge) # mol-biomass / g-reacted
f_CH4 = x_CH4 * f_biogas # mol-CH4 / g-reacted
f_CO2 = x_CO2 * f_biogas # mol-CO2 / g-reacted
thermo = settings.get_default_thermo(thermo)
parsable_name = thermo.chemicals.get_parsable_synonym
isvalid = utils.is_valid_ID
def anaerobic_rxn(chemical):
reactant = chemical.ID
if not isvalid(reactant): reactant = parsable_name(reactant)
if reactant == 'H2SO4':
return Rxn("H2SO4 -> H2S + 2O2", 'H2SO4', 1.)
else:
MW_inv = 1. / chemical.MW
return Rxn(f'{MW_inv}{reactant} -> {f_CH4}CH4 + {f_CO2}CO2 + {f_sludge}WWTsludge',
reactant, 0.91, chemicals=thermo.chemicals)
return PRxn([anaerobic_rxn(i) for i in chemicals])
def aerobic_digestion_reactions(chemicals, MW_sludge, X_combustion=0.74, X_growth=0.22, thermo=None):
# Based on P49 in Humbird et al. Defaults assume 96% of remaining soluble
# organic matter is removed after aerobic digestion, of which 74% is
# converted to water and CO2 and 22% to cell mass
isvalid = utils.is_valid_ID
thermo = settings.get_default_thermo(thermo)
parsable_name = thermo.chemicals.get_parsable_synonym
def growth(chemical):
f = MW_sludge / chemical.MW
reactant = chemical.ID
if not isvalid(reactant): reactant = parsable_name(reactant)
return Rxn(f"{f}{reactant} -> WWTsludge", reactant, X_growth, chemicals=thermo.chemicals)
return PRxn([i.get_combustion_reaction(conversion=X_combustion) + growth(i)
for i in chemicals])
# %% Unit operations
[docs]
@cost('Flow rate', 'Wastewater system', units='kg/hr', CE=551,
cost=50280080., n=0.6, BM=1, kW=7139/1.05, S=393100)
class WastewaterSystemCost(bst.Unit):
"""
Create a unit that estimates the capital cost and electricity demand
of a wastewater treatment system.
Parameters
----------
ins :
Wastewater.
"""
[docs]
class AnaerobicDigestion(bst.Unit):
"""
Create an anaerobic digestion unit operation. The model is based on
stoichiometric reactions and a specified fraction of water evaporated.
Parameters
----------
reactions : ReactionSet, optional
Anaerobic digestion reactions. Default assumes 91% of organic components
is destroyed, of which 86% is converted to biogas and 5% is converted to
sludge. The biogas is assumed to be 51% CH4 and 49% CO2 on a dry molar
basis.
sludge_split : Array, optional
Split between wastewater and sludge.
ins :
* [0] Wastewater
outs :
* [0] Biogas
* [1] Wastewater
* [2] Sludge
"""
purchase_cost = installation_cost = 0
_N_ins = 1
_N_outs = 3
def _init(self, reactions=None, sludge_split=None):
chemicals = self.chemicals
if not reactions:
digestables = get_digestable_organic_chemicals(chemicals)
reactions = anaerobic_digestion_reactions(digestables, chemicals.WWTsludge.MW, thermo=self.thermo)
self.reactions = reactions
if sludge_split is None:
sludge_split = dict(
Water=0.07087,
Ethanol=0.0625,
Furfural=0.06667,
Glycerol=0.07377,
LacticAcid=0.07084,
SuccinicAcid=0.07377,
HNO3=0.0678,
Denaturant=0.07377,
DAP=0.0678,
AmmoniumAcetate=0.07084,
AmmoniumSulfate=0.0678,
H2SO4=0.0678,
NaNO3=0.0678,
Oil=0.07377,
HMF=0.06667,
NH3=0.07048,
Glucose=0.06667,
Xylose=0.07609,
Sucrose=0.06915,
Mannose=0.06915,
Galactose=0.06915,
Arabinose=0.06915,
Extract=0.07084,
Tar=0.7473,
CaO=0.7473,
Ash=0.7473,
NaOH=0.0678,
Lignin=0.744,
SolubleLignin=0.07084,
GlucoseOligomer=0.07143,
GalactoseOligomer=0.07143,
MannoseOligomer=0.07143,
XyloseOligomer=0.07143,
ArabinoseOligomer=0.07143,
Z_mobilis=0.7438,
T_reesei=0.7438,
Cellulose=0.76,
Protein=0.7391,
Enzyme=0.7391,
Xylan=0.75,
Xylitol=0.07377,
Cellobiose=0.06915,
DenaturedEnzyme=0.7391,
Arabinan=1,
Mannan=1,
Galactan=1,
WWTsludge=0.7438,
Cellulase=0.07084
)
remove_undefined_chemicals(sludge_split, chemicals)
default_chemical_dict(sludge_split, chemicals, 0.07087, 0.07087, 0.744)
self.sludge_split = chemicals.isplit(sludge_split)
self._load_components()
def _load_components(self):
self.multi_stream = tmo.MultiStream(thermo=self.thermo)
def _run(self):
feed, = self.ins
biogas, waste, sludge = self.outs
biogas.phase = 'g'
biogas.T = waste.T = sludge.T = 35+273.15
sludge.copy_flow(feed)
self.reactions(sludge)
self.multi_stream.empty()
self.multi_stream.copy_flow(sludge)
self.multi_stream['g'].receive_vent(self.multi_stream['l'], energy_balance=False)
biogas.mol[:] = self.multi_stream.imol['g']
liquid_mol = self.multi_stream.imol['l']
sludge.mol[:] = liquid_mol * self.sludge_split.data
waste.mol[:] = liquid_mol - sludge.mol
biogas.receive_vent(waste)
[docs]
class AerobicDigestion(bst.Unit):
"""
Create an aerobic digestion unit operation. Model is based on
stoichiometric reactions and a specified fraction of water evaporated.
Parameters
----------
ins :
* [0] Wastewater
* [1] Air
* [2] Caustic
outs :
* [0] Vent
* [1] Treated wastewater
reactions : ReactionSet, optional
Aerobic digestion reactions. Defaults assume 96% of remaining soluble
organic matter is removed after aerobic digestion, of which 74% is
converted to water and CO2 and 22% to cell mass.
evaporation : float, optional
Fraction of water evaporated. Defaults to 0.0113.
"""
_N_ins = 3
_N_outs = 2
purchase_cost = installation_cost = 0
def _init(self, reactions=None, evaporation=0.0113):
if not reactions:
chemicals = self.chemicals
digestables = get_digestable_organic_chemicals(self.chemicals)
reactions = aerobic_digestion_reactions(digestables, chemicals.WWTsludge.MW, thermo=self.thermo)
self.reactions = reactions
self.evaporation = evaporation
def _run(self):
waste, air, caustic = self._ins
vent, water = self.outs
vent.phase = 'g'
water.copy_like(waste)
water.mol[:] += caustic.mol
self.reactions.force_reaction(water)
O2 = - water.imass['O2']
N2 = 0.78 / 0.22 * O2
air.empty()
air.imass['O2', 'N2'] += [1.5 * O2, 1.5 * N2]
water.imol['O2'] = 0.
water.imass['N2'] = N2
vent.copy_flow(water, ('CO2', 'O2', 'N2'))
water_index = self.chemicals.index('7732-18-5')
vent.mol[water_index] = water.mol[water_index] * self.evaporation
water.mol[:] -= vent.mol
class SludgeCentrifuge(bst.SolidsSeparator):
"""
Create a centrifuge to separate sludge. The model is based on
component splits.
Parameters
----------
ins :
Inlet fluid to be split.
outs :
* [0] Liquid
* [1] Sludge
split : Defaults to Should be one of the following
* [float] The fraction of net feed in the 0th outlet stream
* [array_like] Componentwise split of feed to 0th outlet stream
* [dict] ID-split pairs of feed to 0th outlet stream
order=None : Iterable[str], defaults to biosteam.settings.chemicals.IDs
Chemical order of split.
moisture_content : float, optional
Moisture content of sludge. Defaults to 0.79 based on stream 623 in [1]_
(or 20% for insolubles).
"""
purchase_cost = installation_cost = 0
def _init(self, split=None, order=None, moisture_content=None, strict_moisture_content=None):
chemicals = self.chemicals
ID_water = chemicals['7732-18-5'].ID # Water must be defined
if split is None:
split = dict(
Furfural=1,
Glycerol=0.8889,
LacticAcid=0.935,
SuccinicAcid=0.8889,
HNO3=0.9344,
Denaturant=0.8889,
DAP=0.9344,
AmmoniumAcetate=0.935,
AmmoniumSulfate=0.9344,
H2SO4=0.935,
NaNO3=0.9344,
Oil=0.8889,
HMF=1,
NH3=0.9388,
H2S=0.9394,
SO2=0.9394,
CO2=0.9333,
NO2=0.9394,
NO=0.9394,
CO=0.9394,
Glucose=1,
Xylose=1,
Sucrose=0.9286,
Mannose=0.9286,
Galactose=0.9286,
Arabinose=0.9286,
Extract=0.935,
Tar=0.05155,
CaO=0.05155,
Ash=0.05155,
NaOH=0.9344,
Lignin=0.04943,
SolubleLignin=0.935,
GlucoseOligomer=0.9,
GalactoseOligomer=0.9,
MannoseOligomer=0.9,
XyloseOligomer=0.9,
ArabinoseOligomer=0.9,
Z_mobilis=0.04991,
T_reesei=0.04991,
Cellulose=0.03846,
Protein=0.05455,
Enzyme=0.05455,
Xylitol=0.8889,
Cellobiose=0.9286,
DenaturedEnzyme=0.05455,
WWTsludge=0.04991,
Cellulase=0.935
)
remove_undefined_chemicals(split, chemicals)
default_chemical_dict(split, chemicals, 0.9394, 0.9286, 0.04991)
split.pop(ID_water) # Remove water from split
if ID_water not in split and moisture_content is None:
# Only set moisture content if water split is not given
moisture_content = 0.79
bst.SolidsSeparator._init(
self, split=split, order=order,
moisture_content=moisture_content, strict_moisture_content=strict_moisture_content
)
def _run(self):
ins = self.ins
retentate, permeate = self.outs # Filtrate, solids
separations.mix_and_split(ins, retentate, permeate, self.split)
separations.adjust_moisture_content(permeate, retentate, self.moisture_content, None, self.strict_moisture_content)
# TODO: Split values seem arbitrary in NREL 2011 model, perhaps work on a better model
class MembraneBioreactor(bst.Splitter):
"""
Create a membrane bioreactor to clarify sludge. The model is based on
component splits.
Parameters
----------
ins :
Inlet fluid to be split.
outs :
* [0] Liquid
* [1] Sludge
split : Defaults to Should be one of the following
* [float] The fraction of net feed in the 0th outlet stream
* [array_like] Componentwise split of feed to 0th outlet stream
* [dict] ID-split pairs of feed to 0th outlet stream
order=None : Iterable[str], defaults to biosteam.settings.chemicals.IDs
Chemical order of split.
"""
purchase_cost = installation_cost = 0
def _init(self, split=None, order=None):
if split is None:
chemicals = self.chemicals
split = dict(
Water=0.1454,
Glycerol=0.125,
LacticAcid=0.145,
SuccinicAcid=0.125,
HNO3=0.1454,
Denaturant=0.125,
DAP=0.1454,
AmmoniumAcetate=0.145,
AmmoniumSulfate=0.1454,
H2SO4=0.1454,
NaNO3=0.1454,
Oil=0.125,
N2=0.1351,
NH3=0.1579,
O2=0.15,
CO2=0.1364,
Xylose=0.25,
Sucrose=0.125,
Mannose=0.125,
Galactose=0.125,
Arabinose=0.125,
Extract=0.145,
NaOH=0.1454,
SolubleLignin=0.145,
GlucoseOligomer=0.1429,
GalactoseOligomer=0.1429,
MannoseOligomer=0.1429,
XyloseOligomer=0.1429,
ArabinoseOligomer=0.1429,
Xylitol=0.125,
Cellobiose=0.125,
Cellulase=0.145
)
remove_undefined_chemicals(split, chemicals)
default_chemical_dict(split, chemicals, 0.15, 0.125, 0.145)
bst.Splitter._init(self, split=split, order=order)
[docs]
class ReverseOsmosis(bst.Unit):
"""
Create a reverse osmosis unit operation for recovering water from brine.
The model is based on a fraction of water recovered.
Parameters
----------
ins :
Inlet fluid to be split.
outs :
* [0] Filtered water
* [1] Brine
water_recovery : float, optional
Water recovered to 0th stream. Defaults to 0.987
"""
_N_ins = 1
_N_outs = 2
def _init(self, water_recovery=0.987):
self.water_recovery = water_recovery
@property
def RO_treated_water(self):
return self.outs[0]
def _run(self):
feed, = self.ins
water, brine = self.outs
water.copy_thermal_condition(feed)
brine.copy_like(feed)
water_index = self.chemicals.index('7732-18-5')
water_flow = brine.mol[water_index]
water_recovered = self.water_recovery * water_flow
water.mol[water_index] = water_recovered
brine.mol[water_index] = water_flow - water_recovered
def _create_cellulosic_ethanol_chemicals():
from biorefineries.cellulosic import create_cellulosic_ethanol_chemicals
return create_cellulosic_ethanol_chemicals()
@bst.SystemFactory(
ID='wastewater_treatment_sys',
outs=[dict(ID='biogas'),
dict(ID='sludge'),
dict(ID='RO_treated_water'),
dict(ID='brine')],
fixed_ins_size=False,
fthermo=_create_cellulosic_ethanol_chemicals,
)
def create_conventional_wastewater_treatment_system(ins, outs,
NaOH_price=None, autopopulate=None
):
"""
Return a system for wastewater treatment as described in Humbird et al. [1]_
The system includes anaerobic and aerobic digestion reactors,
a membrane bioreactor, a sludge centrifuge, and a reverse osmosis unit.
Parameters
----------
ins :
Wastewater streams (without solids). Defaults to all product streams
at run time that are not sold and cannot generate energy through combustion
(i.e. streams that have no sink, no price, and a LHV less that 1 kJ / g).
outs :
* [0] biogas
* [1] sludge
* [2] RO_treated_water
* [3] brine
NaOH_price : float, optional
Price of NaOH in USD/kg. The default is 0.07476.
autopopulate : bool, optional
Whether to automatically add wastewater streams.
Examples
--------
>>> from biosteam import Stream, create_conventional_wastewater_treatment_system, settings
>>> settings.set_thermo(create_conventional_wastewater_treatment_system.fthermo())
>>> feed = Stream(
... ID='wastewater',
... Water=2.634e+04,
... Ethanol=0.07225,
... AceticAcid=24.67,
... Furfural=6.206,
... Glycerol=1.784,
... LacticAcid=17.7,
... SuccinicAcid=3.472,
... DAP=1.001,
... AmmoniumSulfate=17.63,
... HMF=2.366,
... Glucose=2.816,
... Xylose=6.953,
... Arabinose=12.78,
... Extract=65.98,
... Ash=83.52,
... Lignin=1.659,
... SolubleLignin=4.202,
... GlucoseOligomer=6.796,
... GalactoseOligomer=0.01718,
... MannoseOligomer=0.009008,
... XyloseOligomer=2.878,
... ArabinoseOligomer=0.3508,
... Z_mobilis=0.6668,
... Protein=2.569,
... Glucan=0.1555,
... Xylan=0.06121,
... Xylitol=4.88,
... Cellobiose=0.9419,
... Arabinan=0.02242,
... Mannan=0.06448,
... Galactan=0.01504,
... Cellulase=25.4,
... units='kmol/hr'
... )
>>> wwt_sys = create_conventional_wastewater_treatment_system(ins=feed)
>>> wwt_sys.simulate()
>>> wwt_sys.show('cwt100')
System: wastewater_treatment_sys
Highest convergence error among components in recycle
stream M604-0 after 16 loops:
- flow rate 1.13e+03 kmol/hr (0.84%)
- temperature 6.49e-05 K (2.1e-05%)
ins...
[0] wastewater
phase: 'l', T: 298.15 K, P: 101325 Pa
composition (%): Water 94.6
Ethanol 0.000664
AceticAcid 0.295
Furfural 0.119
Glycerol 0.0328
LacticAcid 0.318
SuccinicAcid 0.0818
DAP 0.0264
AmmoniumSulfate 0.465
HMF 0.0595
Glucose 0.101
Xylose 0.208
Arabinose 0.383
Extract 2.37
Ash 0.0167
Lignin 0.0503
SolubleLignin 0.128
GlucoseOligomer 0.244
GalactoseOligomer 0.000617
MannoseOligomer 0.000324
XyloseOligomer 0.0862
ArabinoseOligomer 0.0105
Z_mobilis 0.00328
Protein 0.0117
Glucan 0.00503
Xylan 0.00161
Xylitol 0.148
Cellobiose 0.0643
Arabinan 0.000591
Mannan 0.00209
Galactan 0.000486
Cellulase 0.122
----------------- 5.01e+05 kg/hr
outs...
[0] biogas
phase: 'g', T: 307.76 K, P: 101325 Pa
composition (%): Water 3.18
Ethanol 2.46e-05
AceticAcid 0.0019
Furfural 0.00296
Glycerol 1.43e-08
LacticAcid 8.25e-07
SuccinicAcid 2.88e-09
CH4 26.6
CO2 70.2
------------ 2.13e+04 kg/hr
[1] sludge
phase: 'l', T: 307.88 K, P: 101325 Pa
composition (%): Water 46
Ethanol 5.26e-05
AceticAcid 0.0267
Glycerol 0.0048
LacticAcid 0.0262
SuccinicAcid 0.012
DAP 0.0976
AmmoniumSulfate 1.72
SO2 0.000601
Arabinose 0.0338
Extract 0.195
Ash 2.56
NaOH 1.58
Lignin 7.54
SolubleLignin 0.0105
GlucoseOligomer 0.0312
GalactoseOligomer 7.88e-05
MannoseOligomer 4.13e-05
XyloseOligomer 0.011
ArabinoseOligomer 0.00134
Z_mobilis 0.0406
Protein 0.143
Glucan 0.0229
Xylan 0.0226
Xylitol 0.0217
Cellobiose 0.00568
Arabinan 0.0103
Mannan 0.0363
Galactan 0.00847
WWTsludge 39.8
Cellulase 0.01
----------------- 2.57e+03 kg/hr
[2] RO_treated_water
phase: 'l', T: 307.79 K, P: 101325 Pa
composition (%): Water 100
----- 4.16e+05 kg/hr
[3] brine
phase: 'l', T: 307.79 K, P: 101325 Pa
composition (%): Water 48.7
Ethanol 1.35e-05
AceticAcid 0.00609
Furfural 0.00244
Glycerol 0.000675
LacticAcid 0.00763
SuccinicAcid 0.00169
DAP 1.11
AmmoniumSulfate 19.6
HMF 0.00124
SO2 0.01
Glucose 0.00244
Xylose 0.00861
Arabinose 0.00791
Extract 0.0568
Ash 0.267
NaOH 23.5
Lignin 0.519
SolubleLignin 0.00306
GlucoseOligomer 0.00576
GalactoseOligomer 1.46e-05
MannoseOligomer 7.63e-06
XyloseOligomer 0.00203
ArabinoseOligomer 0.000248
Z_mobilis 1.99e-05
Protein 7.32e-05
Glucan 0.206
Xylan 0.0657
Xylitol 0.00305
Cellobiose 0.00133
Arabinan 0.0237
Mannan 0.0837
Galactan 0.0195
WWTsludge 5.9
Cellulase 0.00292
----------------- 1.12e+04 kg/hr
"""
biogas, sludge, RO_treated_water, brine = outs
RO_treated_water.register_alias('recycled_water')
if NaOH_price is None: NaOH_price = 0.07476
air = bst.Stream('air_lagoon', O2=51061, N2=168162, phase='g', units='kg/hr')
caustic = bst.Stream('caustic', Water=2252, NaOH=2252,
units='kg/hr', price=NaOH_price)
wastewater_mixer = bst.Mixer('M601', ins or [])
wastewater_mixer.autopopulate = False if autopopulate is None else autopopulate
@wastewater_mixer.add_specification(run=True)
def autopopulate_waste_streams():
if wastewater_mixer.autopopulate and not wastewater_mixer.ins:
sys = wastewater_mixer.system
streams = bst.FreeProductStreams(sys.streams)
wastewater_mixer.ins.extend(streams.noncombustible_slurries)
for i in sys.facilities:
if isinstance(i, bst.BlowdownMixer): wastewater_mixer.ins.append(i.outs[0])
WWTC = WastewaterSystemCost('WWTC', wastewater_mixer-0)
anaerobic_digestion = AnaerobicDigestion('R601', WWTC-0, (biogas, '', ''))
recycled_sludge_mixer = bst.Mixer('M602', ('', anaerobic_digestion-1))
caustic_over_waste = caustic.imol['Water', 'NaOH'] / 2544301
air_over_waste = air.imol['O2', 'N2'] / 2544301
air.mol[:] = 0.
waste = recycled_sludge_mixer-0
aerobic_digestion = AerobicDigestion('R602', (waste, air, caustic),
outs=('evaporated_water', ''))
@aerobic_digestion.add_specification
def update_aerobic_input_streams():
waste, air, caustic = aerobic_digestion.ins
F_mass_waste = waste.F_mass
caustic.imol['Water', 'NaOH'] = F_mass_waste * caustic_over_waste
air.imol['O2', 'N2'] = F_mass_waste * air_over_waste
aerobic_digestion._run()
membrane_bioreactor = MembraneBioreactor('S601', aerobic_digestion-1)
sludge_splitter = bst.Splitter('S602', membrane_bioreactor-1, split=0.96)
fresh_sludge_mixer = bst.Mixer('M603', (anaerobic_digestion-2, sludge_splitter-1))
sludge_centrifuge = SludgeCentrifuge('S603', fresh_sludge_mixer-0, outs=('', sludge))
bst.Mixer('M604', [sludge_splitter-0, sludge_centrifuge-0], 0-recycled_sludge_mixer)
ReverseOsmosis('S604', membrane_bioreactor-0, outs=(RO_treated_water, brine))
create_wastewater_treatment_system = create_conventional_wastewater_treatment_system
